System and method for code division multiple access communication, and base station and terminal apparatus for same system

(1) Field of the Invention

The present invention relates to a code division multiple access communicating system, a base station for a code division multiple access communicating system and a terminal apparatus for a code division multiple access communicating system, and a code division multiple access communicating method, suitable for a communication of spread spectrum information with a base station over a commonly used channel.

(2) Description of Related Art

With an increase of demand for portable telephones, efficient use of a frequency becomes a serious problem in a mobile communication system. In such circumstances, a code division multiple access (CDMA) communicating system using a spread spectrum technique draws attention as a system having a high frequency efficiency, searches on it being vital for the purpose of practical application thereof.

In a CDMA communicating system, the user uses a mobile station (hereinafter referred to as MS) to transmit a frame to a base station (hereinafter referred to as BS) at a transmittable timing according to notice information transmitted from the BS when making a telephone call, for example.

A frame transmitted from a portable telephone to a BS is transmitted at a timing in a predetermined cycle, as shown by a plurality of arrows in FIG. 24 ( b ). In FIG. 24 ( b ), there are, for example, four timings that the portable telephone can access to the BS in one cycle. Each portable telephone randomly selects any one of the timings to transmit a frame to the BS.

FIG. 24 ( b ) shows that MSs 1 a through 4 a transmit frames to the BS at different timings. Incidentally, frames transmitted from the MSs 1 a through 4 a are spread using a spreading code and transmitted to the BS. The MSs 1 a through 4 a transmit frames at different timings, so that a timing of a phase of the spreading code shifts with a transmit timing even if the spreading code used by MSs 1 a through 4 a has the same system. The BS can thereby de-spread each of the frames transmitted from the MSs 1 a through 4 a on the basis of the spreading code having a phase different from one another so as to extract the frame.

When the BS receives frames transmitted from the MSs 1 a through 4 a , the BS transmits ACKs (Acknowledge) as acknowledge information to the MSs 1 a through 4 a (transmitting side), as shown in FIG. 24 ( a ). In ACKs, plural pieces of acknowledge information for the MS 1 a through 4 a are collected in a transmission frame, and transmitted.

Each of the MSs 1 a through 4 a receives a frame outputted from the BS after transmitting the frame to confirm whether or not the frame having been transmitted to the BS is received by the BS. When there is acknowledge information to the frame having been transmitted from itself in the received frame, each of the MSs 1 a through 4 a confirms reception of the frame having been transmitted to the BS by the BS. When each of the MSs 1 a through 4 a does not receive acknowledge information to the frame having been transmitted from itself within a predetermined period after transmitting the frame to the BS, the MS performs a re-transmitting process. When receiving ACK to the information having been transmitted from itself within a predetermined period after transmitting the frame to the BS, each of the MSs 1 a through 4 a transmits a remaining frame when having the remaining frame to be continuously transmitted to the BS.

When transmitting a plurality of frames to the BS, each of the MSs 1 a through 4 a recevies ACK each time the MS transmits a frame, then transmits a remaining frame.

In the case where each of the MSs 1 a through 4 a transmits one frame, receives ACK shown in FIG. 24 ( a ), and the MS 1 a and MS 2 a transmit remaining packets as shown in FIG. 24 ( b ), each of the MS 1 a and the MS 2 a possibly access to the BS at the same timing since each of the MS 1 a and the MS 2 a can randomly select an access timing among four access timings in one frame.

At this time, information transmitted from the MS 1 a and the MS 2 a is spread using the spreading code having the same phase, so that the BS cannot separate the information transmitted from the MS 1 a and the MS 2 a , hence the information is lost. The MS 1 a and the MS 2 a therefore cannot receive acknowledge information to the frames that the MS 1 a and the MS 2 a have secondary transmitted to the BS, thus the MSs 1 a and 2 a have to perform the re-transmitting process. This leads to a decrease of a throughput of the communicating system.

In the light of the above disadvantage, an object of the present invention is to provide a code division multiple access communicating system, a base station for a code division multiple access communicating system and a terminal apparatus for a code division multiple access communicating system, and a code division multiple access communicating method, in which when a terminal apparatus continuously transmits remaining information after receiving acknowledge information from a base station, the terminal apparatus again accesses to the base station according to an order of a piece of acknowledge information for itself among plural pieces of acknowledge information having been put in a transmission frame, whereby conflict of access timings between terminal apparatus whose acknowledge information has been put in the transmission frame is avoided, thus a decrease of the throughput can be suppressed.

A code division multiple access communicating system according to this invention comprises a base station and a plurality of terminal apparatus exchanging spread spectrum information with the base station over a commonly used channel when communicating with the base station.

The base station comprises a receiving means for receiving an access signal from each of the plural terminal apparatus at the time of random access from each of the plural terminal apparatus, and an acknowledge information transmitting means for collectively putting plural pieces of acknowledge information to reception of the access signals for the plural terminal apparatus in a transmission frame, and transmitting the frame to the plural terminal apparatus when receiving means receives the access signals from the plural terminal apparatus.

Each of the plural terminal apparatus comprises an acknowledge information receiving means for receiving the plural pieces of acknowledge information from the acknowledge information transmitting means of the base station, and a transmitting means for again accessing to the base station according to an order of acknowledge information for its own terminal apparatus among the plural pieces of acknowledge information received from the base station by the acknowledge information receiving means was put after randomly accessing to the base station when there is remaining information to be continuously transmitted to the base station, and transmitting the remaining information.

In the code division multiple access communicating system of this invention, the terminal apparatus again accesses to the base station according to an order of acknowledge information for itself among plural pieces of acknowledge information received from the base station by the acknowledge information receiving means to transmit remaining information, whereby conflict between the terminal apparatus transmitting remaining information is avoided and a decrease of the throughput is suppressed.

A base station for a code division multiple access communicating system of this invention comprises a receiving means for receiving an access signal from each of a plurality of terminal apparatus at the time of random access from each of the plural terminal apparatus, and an acknowledge information transmitting means for collectively putting plural pieces of acknowledge information to reception of the access signals for the plural terminal apparatus in a transmission frame in the order the access signals were received from the plural terminal apparatus when receiving the access signals from the plural terminal apparatus by the receiving means, and transmitting the transmission frame to the plural terminal apparatus so that the plural terminal apparatus having remaining information to be continuously transmitted to the base station again access to the base station in a predetermined order to transmit the remaining information.

Accordingly, the base station for a code division multiple access communicating system of this invention collectively puts plural pieces of acknowledge information for a plurality of terminal apparatus in a transmission frame in the order the base station received access signals from the plural terminal apparatus and transmits the transmission frame to the plural terminal apparatus so that the plural terminal apparatus having remaining information to be continuously transmitted to the base station again accesses to the base station in a predetermined order, whereby conflict between terminal apparatus transmitting remaining information is avoided, and a decrease of the throughput is thus suppressed.

A terminal apparatus for a code division multiple access communicating system of this invention comprises a randomly accessing means for randomly accessing to a base station, an acknowledge information receiving means for receiving plural pieces of acknowledge information from the base station, the base station collectively putting acknowledge information for the terminal apparatus along with acknowledge information for other terminal apparatus in a transmission frame, and transmitting the transmission frame to the terminal apparatus when receiving an access signal from the terminal apparatus at the time of random access by the terminal apparatus to the base station, and a transmitting means for again accessing to the base station according to an order of the order acknowledge information for the terminal apparatus of its own among the plural pieces of acknowledge information received from the base station by the acknowledge information receiving means after the terminal apparatus randomly accesses to the base station if there is remaining information to be continuously transmitted to the base station, and transmitting the remaining information.

Accordingly, in the terminal apparatus for a code division multiple access communicating system of this invention, the transmitting means again accesses to the base station according to an order of acknowledge information for a terminal apparatus of its own among plural pieces of acknowledge information received from the base station by the acknowledge information receiving means after randomly accessing to the base station, whereby conflict between terminal apparatus transmitting remaining information, and a decrease of the throughput is thus suppressed.

A code division multiple access communicating method of this invention comprises the steps of an acknowledge information transmitting step performed in a base station of collectively putting acknowledge information for a plurality of terminal apparatus in a transmission frame when the base station receives access signals from the plural terminal apparatus at the time of random access from the plural terminal apparatus, and transmitting the transmission frame to the plural terminal apparatus, and a transmitting step performed in each of the plural terminal apparatus of again accessing to the base station according to an order of acknowledge information for itself among the plural pieces of acknowledge information received from the base station in the transmission frame after a random access to the base station if there is remaining information to be continuously transmitted to the base station to transmit the remaining information.

According to the code division multiple access communicating method of this invention, each of a plurality of the terminal apparatus again accesses to the base station according to an order of acknowledge information for itself among plural pieces of acknowledge information received from the base station if having remaining information to be continuously transmitted to the base station after randomly accessing to the base station to transmit the remaining information at the transmitting step, whereby conflict between terminal apparatus transmitting remaining information is avoided, and a decrease of the throughput is thus suppressed.

FIG. 1 is a block diagram showing an aspect of this invention;

FIG. 2 is a block diagram showing a structure of a CDMA communicating system according to a first embodiment of this invention;

FIGS. 3 ( a ) and 3 ( b ) illustrate examples of structures of frames exchanged between an MS and a BS;

FIG. 4 is a block diagram showing an example of a structure of the MS according to the first embodiment of this invention;

FIG. 5 is a block diagram showing an example of a structure of the BS according to the first embodiment of this invention;

FIG. 6 is a diagram illustrating a signal sequence in the CDMA communicating system according to the first embodiment of this invention;

FIGS. 7 ( a ) and 7 ( b ) are time charts illustrating an operation of the CDMA communicating system according to the first embodiment of this invention;

FIG. 8 is a flowchart illustrating an operation of the MS according to the first embodiment of this invention;

FIGS. 9 ( a ) and 9 ( b ) are time charts illustrating an operation of a CDMA communicating system according to a first modification of the first embodiment of this invention;

FIG. 10 is a flowchart illustrating an operation of an MS according to the first modification of the first embodiment of this invention;

FIGS. 11 ( a ) and 11 ( b ) are time charts illustrating a CDMA communicating system according to a second modification of the first embodiment of this invention;

FIG. 12 is a flowchart illustrating an operation of a BS according to the second modification of the first embodiment of this invention;

FIGS. 13 ( a ) and 13 ( b ) are time charts illustrating an operation of a CDMA communicating system according to a third modification of the first embodiment of this invention;

FIGS. 14 ( a ) and 14 ( b ) are time charts illustrating a CDMA communicating system according to a fourth modification of the first embodiment of this invention;

FIG. 15 is a flowchart illustrating an operation of an MS according to the fourth modification of the first embodiment of this invention;

FIGS. 16 ( a ) and 16 ( b ) are time charts illustrating an operation of a CDMA communicating system according to a fifth modification of the first embodiment of this invention;

FIG. 17 is a flowchart illustrating an operation of an MS according to the fifth modification of the first embodiment of this invention;

FIG. 18 is a flowchart illustrating an operation of a BS according to the fifth modification of the first embodiment of this invention;

FIGS. 19 ( a ) and 19 ( b ) are time charts illustrating an operation of a CDMA communicating system according to a sixth modification of the first embodiment of this invention;

FIG. 20 is a flowchart illustrating an operation of a BS according to the sixth modification of the first embodiment of this invention;

FIGS. 21 ( a ) and 21 ( b ) are time charts illustrating an operation of a CDMA communicating system according to a seventh modification of the first embodiment of this invention;

FIG. 22 is a flowchart illustrating an operation of an MS according to the seventh modification of the first embodiment of this invention;

FIG. 23 is a flowchart illustrating an operation of a BS according to the seventh modification of the first embodiment of this invention; and

FIGS. 24 ( a ) and 24 ( b ) are time charts illustrating an operation of a CDMA communicating system.

(a) Description of an Aspect of the Invention

Now, description will be made of an aspect of the present invention with reference to the drawing.

As shown in FIG. 1, a code division multiple access communicating system 100 described in claim 1 comprises a base station 80 , and a plurality of terminal apparatus 60 - 1 thorugh 60 -I (I: an integer not less than 2) exchanging spread spectrum information with the base station 80 over a commonly used channel when communicating with the base station 80 .

The base station 80 comprises a receiving means 80 a receiving access signals from the plural terminal apparatus 60 - 1 through 60 -I at the time of random accesses from the terminal apparatus 60 - 1 through 60 -I, and an acknowledge information transmitting means 80 b putting plural pieces of acknowledge information to reception of the access signals in a transmission frame when the receiving means 80 a receives the access signals from the terminal apparatus 60 - 1 through 60 -I, and transmitting the transmission frame to the plural terminal apparatus 60 - 1 through 60 -I.

Each of the terminal apparatus 60 - 1 through 60 -I comprises an acknowledge information receiving means 60 a receiving the plural pieces of acknowledge information from the acknowledge information transmitting means 80 b of the base station 80 , and a transmitting means 60 b again accessing to the base station according to an order of a piece of acknowledge information for a terminal apparatus of its own among the plural pieces of acknowledge information received from the base station 80 by the acknowledge information receiving means 70 a when the terminal apparatus has remaining information to be continuously transmitted to the base station 80 after randomly accessing to the base station 80 .

According to the code division multiple access communicating system described in claim 1 of this invention, the terminal apparatus again accesses to the base station according to an order of a piece of acknowledge information for itself among plural pieces of acknowledge information received from the base station by the acknowledge information receiving means to transmit remaining information, whereby conflict between terminal apparatus transmitting remaining information is avoided, a decrease of the throughput is thus suppressed.

Hereinafter, embodiment of the present invention will be described with reference to the drawings.

(b1) Description of a First Embodiment

FIG. 2 is a block diagram showing a structure of a CDMA communicating system 1 according to a first embodiment of this invention. As shown in FIG. 2, the CDMA communicating system 1 comprises a BS 1 B and a plurality of MSs 1 A through nA (n is an integer).

Hereinafter, description will be made on the assumption that the MSs 1 A through nA are portable telephones. Description in the case of another mobile equipment is omitted, but this invention is applicable to another mobile equipment in the same or similar manner.

Further, the description will be made on a case where each of the portable telephones (MSs) and the base station (BS) transmit/receive information over a common control channel before the portable telephone initiates a call therebetween.

Each of the MSs 1 A through nA is a slave station in a mobile communication. When an MS iA (i; an integer) makes a telephone call to another MS jA [j (j ≠i); an integer), the MS iA puts confirmation information such as its own telephone number or the like in a frame (up), and transmits the frame to the BS 1 B.

As shown in. FIG. 3 ( b ), each of the MSs 1 A through nA puts information such as user/control information U/C, a terminating node information (TN) designating a terminating place, continuation bits (W) showing that there is a frame to be continuously transmitted, a sequence number (Sequence Number) showing a serial number of a frame to be continuously transmitted, a packet number (Packet ID: PID) as an identifier showing a frame transmitted from its own terminal and the like along with information on its telephone number and the like. Incidentally, each of the MSs 1 A through nA can transmit other frame (up) in other format structure.

Each of the MSs 1 A through nA receives, as shown in FIG. 3 ( a ), a frame (down) 3 stuffed with ACK mode (Mo) showing that a transmission frame (down) is ACK, the number of put ACKs (NA) and ACK information (Packet ID: PID) from the BS 1 B.

With respect to the ACK information (acknowledge information), a PID in the frame (up) 2 transmitted from each of the MS 1 A through nA is put as the ACK information in the frame (down) 3 , and the frame (down) 3 is stuffed with PIDs of a plurality of MSs and transmitted. The number of stuffed ACKs shows the number of PIDs put in the frame (down) 3 . Incidentally, PID as ACK information will be occasionally referred to simply as acknowledge information. Further, PID in the frame (down) in the drawings will be denoted as “MS 1 A”, “MS 2 A” or the like for the sake of convenience, wherein “MS 1 A” in the frame (down) 3 in the drawings signifies a PID of the MA 1 A, for example.

Hereafter, description will be made in the case where a maximum number of pieces of acknowledge information put in one frame (down) 3 is, for example, “7”.

Each of the MSs 1 A through nA transmits a frame (up) 2 spread using a spreading code assigned to the plural MSs 1 A through nA over a common control channel commonly used by the plural MSs 1 A through nA and the BS 1 B, and receives a frame (down) 3 transmitted from the BS 1 B.

When continuously transmitting remaining information [frames stuffed with remaining information will be referred to as “remaining frames” hereinafter] after transmitting the frames (up) 2 to the BS 1 B, the MS 1 A through nA have accesses to transmit remaining frames (up) 2 in the order acknowledge information was put in the frame (down) 3 received from the BS 1 B.

When each of the MSs 1 A through nA first transmits a frame (up) 2 to the BS 1 B, each of the MSs 1 A through nA randomly selects an access timing at which the frame (up) 2 is transmitted on the basis of notice information transmitted from the BS 1 B, and transmits the frame (up) 2 .

Incidentally, it is assuemd that there are four access timings in one cycle. Correspondingly to four access timings, a phase of the spreading code in a common system used by the MSs 1 A through nA shifts at each timing, so that a signal transmitted at a different timing is spread by the spreading code having a phase different from one another. At the same access timing in each cycle, a signal is spread by the spreading code having the same phase.

A timing at which each of the MSs 1 A through nA transmits a remaining frame is set according to an order put in the received frame 3 , as stated above. In concrete, when acknowledge information is put in the first position in the frame 3 , an access timing is set to the first timing among four access timings. When acknowledge information is put in the second position, an access timing is set to the second access timing. When acknowledge information is put in the fourth position, an access timing is set to the fourth access timing.

If each of the MSs 1 A through nA receives no acknowledge information to a frame (up) 2 having been transmitted even when a predetermined time is elapsed, after transmitting the frame (up) 2 to the BS 1 B, for example, each of the MSs 1 A through nA performs a re-transmitting process.

To this end, the MS according to the first embodiment comprises a receiving unit 10 , a transmitting unit 20 , a duplexer 30 , a CPU 40 and an antenna 50 , as shown in FIG. 4 .

The transmitting unit 20 transmits a frame (up) 2 to the BS 1 B. The transmitting unit 20 can transmit a spread spectrum frame obtained by spreading spectrum of a signal from the CPU 40 using the spreading code having a phase corresponding to an access timing, and can transmit other frame (up) as well.

To this end, the transmitting unit 20 comprises, as shown in FIG. 4, a spreading unit 21 , filters for waveform shaping 22 and 23 , digital/analog converters. (D/A) 24 and 25 , an orthogonal modulating circuit 26 and a frequency converting circuit 27 .

A spread signal obtained by spreading a signal from the CPU 40 using the spreading code by the spreading unit 21 is separated into a code of I channel and a code of Q channel, inputted to the filters 22 and 23 , respectively, in which unnecessary bands are eliminated, then inputted to the digital/analog converting unit (D/A) 24 for I channel components and the digital/analog converting unit (D/A) 25 for Q channel components, respectively, to be converted into corresponding analog signals.

The analog signal of I channel and the analog signal of Q channel converted in the D/As 24 and 25 , respectively, are orthogonal-modulated into an orthogonal-modulated signal in the orthogonal modulating circuit 26 , up-converted from an intermediate frequency signal (IF signal) to a radio frequency signal (RF signal) in the frequency converting circuit 27 , led to the antenna 50 via the duplexer 30 , and transmitted.

The receiving unit 10 shown in FIG. 4 receives a frame (down) 3 transmitted from the BS 1 B. The receiving unit 10 comprises a frequency converting circuit 11 , an orthogonal detecting circuit 12 , analog/digital converters 13 and 14 , a path searching circuit 17 , a de-spreading unit 16 , and filters for waveform shaping 18 and 19 . Incidentally, the receiving unit 10 can also receive other frame (down) in a format structure different from that of a frame (down) 3 transmitted from the BS 1 B.

A signal (redio frequency signal: RF signal) received through the antenna 50 and the duplexer 30 is down-converted into an intermediate frequency signal (IF signal) in the frequency converting circuit 11 , and separated into I channel components and Q channel components in the orthogonal detecting circuit 12 . The I channel components and the Q channel components are converted into digital signals in the analog/digital converter (A/D) 13 for I channel components and the analog/signal converter (A/D) 14 for Q channel components, respectively.

The digital signals from the A/D converters 13 and 14 are led to the filters 18 and 19 , in which unnecessary bands in the digital signals are eliminated, input to the de-spreading unit 16 to be de-spread using a predetermined code. A signal of a de-spread frame (down) 3 is outputted to the CPU 40 . The de-spreading unit 16 performs de-spreading on the basis of a set timing from the path searching circuit 17 .

The CPU 40 shown in FIG. 4 randomly selects an access timing among four access timings based on information notifying of timings at which the MS accesses to the BS 1 B transmitted from the BS 1 B when transmitting or the like a frame (up) 2 to the BS 1 B over a common control channel, and controls each part so as to transmit the frame (up) 2 to the BS 1 B. The CPU 40 also determines whether or not there is acknowledge information to the frame having been transmitted from its own apparatus in a received frame (down) 3 . Additionally, when continuously transmitting a remaining frame (up) 2 , the CPU 40 determines an order of a piece of acknowledge information to the frame (up) 2 having been transmitted from its own apparatus among plural pieces of acknowledge information put in the frame (down) 3 , and makes the spreading unit 21 output a transmit signal so as to transmit the remaining frame (up) 2 at an access timing according to that order.

As stated above, each of the MSs 1 A through nA has a function of a randomly accessing means for randomly accessing to the BS 1 B, a function of an acknowledge information receiving means for receiving plural pieces of acknowledge information put in a frame (down) 3 , in which frame the BS 1 B collectively puts acknowledge information for other MSs together with the acknowledge information for the relevant MS, and which frame is transmitted from the BS 1 B when the BS 1 B receives access signals from the MS 1 A through nA having randomly accessed to the BS 1 B. Each of the MSs 1 A through nA also has a function of a transmitting means for again accessing to the BS 1 B to transmit a remaining frame (up) 2 according to an order of a piece of acknowledge information for its own terminal among the plural pieces of acknowledge information received from the BS 1 B after randomly accessing to the BS 1 B if the terminal has the remaining frame (remaining information) 2 to be continuously transmitted to the BS 1 B.

The BS 1 B shown in FIG. 2 is a base station in the mobile communication, the BS 1 B receiving a frame (up) 2 from each of a plurality of the MSs. 1 A through nA over the common control channel and transmitting a frame (down) 3 thereto. When receiving frames (up) 2 transmitted from the MSs 1 A through nA, the BS 1 B transmits data as shown in FIG. 3 ( a ) as acknowledge information. Incidentally, the BS 1 B can exchange information with other BS over an ATM network (not shown in FIG. 2 ), and set a speech channel between an MS accommodated in another BS and an MS accommodated in itself. The BS 1 B can also transmit a frame (down) in a format structure different from that of a frame (down) shown in FIG. 3 ( a ), and receive other frame (up).

To this end, the BS 1 B comprises, as shown in FIG. 5, a receiving unit 10 - 1 , a transmitting unit 20 - 1 , a duplexer 30 , a CPU 40 - 1 and an antenna 50 .

The transmitting unit 20 - 1 comprises a spreading unit 21 , filters 22 and 23 , D/As 24 and 25 , an orthogonal modulating circuit 26 and a frequency converting circuit 27 , similarly to the transmitting unit 20 of each of the MSs 1 A through nA. The receiving unit 10 - 1 comprises a frequency converting circuit 11 , an orthogonal detecting circuit 12 , A/Ds 13 and 14 , a path searching circuit 17 and filters for waveform shaping 18 and 19 , similarly to the receiving unit 10 . However, the receiving unit 10 - 1 comprises a plurality of de-spreading units 16 - 1 through 16 - 4 , dissimilarly to the receiving unit 10 shown in FIG. 4 .

Correspondingly to that there are four access timings in one cycle at which each of the MSs 1 A through nA can transmit a frame (up) 2 , the receiving unit 10 - 1 has the plural de-spreading units 16 - 1 through 16 - 4 in order to de-spread a signal transmitted at each timing using a spreading code having a different phase.

When the receiving unit 10 - 1 receives a signal spread using the spreading code having a different phase transmitted from each of the MSs 1 A through nA, any one of the de-spreading units 16 - 1 through 16 - 4 de-spreads the received signal using the spreading coce having a desired phase, and notifies of the extracted signal the CPU 40 - 1 .

The CPU 40 - 1 performs CRC check and the like on the basis of a signal received from any one of the de-spreading units 16 - 1 through 16 - 4 , and determines contents transmitted from each of the MSs 1 A through nA to confirm the reception. The CPU 40 - 1 then copies a PID put in each of a plurality of received signals [frames (up) 2 ] in order to send acknowledge information to the reception, and outputs signals put in a frame (down) 3 to the transmitting unit 20 - 1 .

After that, the transmit signals outputted from the CPU 40 - 1 undergo spectrum spreading and the like using the spreading code having a desired phase in the transmitting unit 20 - 1 , and transmitted from the antenna 50 .

As above, the BS 1 B has a function as a receiving means for receiving frames (up) 2 from a plurality of the MSs 1 A through nA at the time of random accesses from the MSs 1 A through nA. The BS 1 B also has a function as an acknowledge information transmitting means for putting plural pieces of acknowledge information in a frame (down) 3 and transmitting the frame 3 when receiving frames (up) 2 . Namely, when the BS 1 B receives access signals from the MSs 1 A through nA, the BS 1 B puts acknowledge information to reception of the access signals for the plural MSs in a frame (down) 3 in the order the BS 1 B received the access signals from the MSs and transmits the frame (down) 3 to the MS 2 1 A through nA, so that MSs having remaining frames (up) 2 to be continuously transmitted to the BS 1 B again access to the MS 1 B in a predetermined order to transmit the remaining frames (up) 2 .

FIG. 6 is a diagram illustrating a signal sequence in a CDMA communicating system according to this embodiment of this invention. As shown in FIG. 6, an MS kA (k; k=1 through n) selects an access timing, and transmits a frame (up) 2 to the BS 1 B. When the BS 1 B receives the frame (up) 2 transmitted from the MS kA, the BS 1 B puts acknowledge information in a frame (down) 3 , and transmits the frame (down) 3 to the MS kA.

The MS kA having transmitted the frame (up) 2 to the BS 1 B performs a timer monitoring in order to confirm, for example, reception of ACK. When not receiving ACK in response to the frame (up) 2 having been transmitted within a predetermined period, the MS kA performs a re-transmitting process.

When receiving a frame (down) 3 transmitted from the BS 1 B and confirming reception of acknowledge information to the frame (up) 2 having been transmitted put in the frame (down) 3 , the MS kA transmits a remaining frame (up) 2 if having the remaining frame (up) 2 to be continuously transmitted.

After the above control signals are exchanged, a communication is initiated.

Next, an operation of the CDMA communicating system 1 according to the first embodiment will be described with reference to time charts shown in FIGS. 7 ( a ) and 7 ( b ), and a flow chart shown in FIG. 8 .

In the following description, each of the MSs 1 A through 3 A is assumed to transmit a remaining frame (up) 2 .

In the CDMA communicating system with the above structure according to the first embodiment, each of the MSs 1 A through 3 A randomly selects an access timing among four access timings within a cycle when transmitting a frame (up) 2 to the BS 1 B, and transmits the frame (up) 2 .

Assuming here that the MS 1 A through 3 A transmit frames (up) 2 at different access timings (t- 1 , t- 3 and t- 4 ) in cycle T- 1 , as shown in FIG. 7 ( b ), for example.

Each of the MSs 1 A through 3 A starts a timer after transmitting a frame (up) 2 (Step S 1 ).

When the BS 1 B confirms reception of the frames (up) 2 transmitted from the MSs 1 A through 3 A, the BS 1 B puts acknowledge information to be transmitted to the MSs 1 A through 3 A in a frame (down) 3 in the order the BS 1 B received the frames (up) 2 , and transmits the frame (down) 3 [in cycle T-b in FIG. 7 ( a ), for example].

Each of the MSs 1 A through 3 A receives the frame (down) 3 transmitted from the BS 1 B in cycle T- 3 in FIG. 7 ( b ), for example (Step S 2 ), and determines in cycle T- 4 whether or not the received frame (down) 3 is in ACK mode and has the same PID as a PID that the MS has transmitted (Step S 3 ).

When the frame received from the BS 1 B is not in ACK mode or the PID does not coincide with the PID that the MS has transmitted, the MS determines whether or not the started timer is up (from NO route at Step S 3 to Step S 8 ). When the timer has counted up to the maximum value, the MS performs a re-transmitting process (from YES route at Step S 8 to Step S 9 ). When the timer is not up, the MS moves to a process of receiving a frame (from NO route at Step S 8 to Step S 2 ).

Incidentally, when a PID is detected from a received frame (down) 3 , a count value of the timer is cleared.

To the contrary, when the PID is the same as the PID that the MS has transmitted, each of the MSs 1 A through 3 A determines whether or not there is a frame (up) 2 to be continuously transmitted (from YES route at Step S 3 to Step S 4 ). When there is no frame (up) 2 , the MS completes the transmission (from NO route at Step S 4 to Step S 10 ).

When there is a remaining frame (up) 2 , each of the MSs 1 A through 3 A detects a position (order) of its own PID (acknowledge information) among plural pieces of acknowledge information put in the received frame (down) 3 (from YES route at Step S 4 to Step S 5 ) sets a transmit timing to a position of the detected PID (Step S 6 ), and transmits the remaining frame (up) 2 (Step S 7 ).

Each of the MSs 1 A through 3 A confirms an order of acknowledge information to the frame (up) 2 having been transmitted from itself in the frame (down) 3 received in cycle T- 3 [refer to FIG. 7 ( a )]. Here, the MS 1 A transmits a remaining frame (up) 2 at access timing t- 1 in cycle T- 5 since the acknowledge information for the MS 1 a is placed in the first position, the MS 2 A at access timing t- 2 , and MS 3 A at access timing t- 3 .

If there is still a remaining frame (up) 2 , processes similar to the above (Steps S 1 through S 7 , and Steps S 8 through S 10 ) are performed.

In the CDMA communicating system according to the first embodiment of this invention, each of the MSs 1 A through 3 A again accesses to the BS 1 B according to an order of a piece of acknowledge information for its own terminal apparatus among plural pieces of acknowledge information put in a frame (down) 3 received from the BS 1 B, and transmits a remaining frame (up) 2 if transmitting the remaining frame (up) 2 after transmitting a frame, for example. Consequently, it is possible to avoid conflict among the MSs 1 A through 3 A transmitting remaining frames (up) 2 thus suppress a decrease of the throughput.

(b2) Description of a First Modification of the First Embodiment

According to a first modification of the first embodiment, the BS 1 B and the MSs 1 A through nA have functions almost similar to those described in the first embodiment. However, in a CDMA communicating system (denoted by a different reference character in order to discriminate it from the above CDMA communicating system 1 ) 1 - 1 , each of the MSs 1 A through nA transmits a remaining frame (up) 2 within a set period of transmit timings, dissimilarly to the CDMA communicating system 1 according to the first embodiment. In the description on the first modification, like reference characters designate like or corresponding parts in the first embodiment.

Each of the MSs 1 A through nA receives acknowledge information to a transmitted frame (up) 2 , and transmits a remaining frame (up) 2 at an access timing within a period set according to an order of acknowledge information to its own frame (up) 2 put in a frame (down) 3 .

For example, a period of access timings during which a remaining frame (up) 2 can be transmitted can be set to a different cycle according to an order of acknowledge information put in the frame (down) 3 . An access timing at which the remaining frame (up) 2 is transmitted is randomly selected among four access timings in each cycle.

Hereinafter, the description will be proceeded on the above assumption.

Incidentally, the CPU 40 shown in FIG. 4 sets a timing at which the remaining frame (up) 2 is transmitted.

FIGS. 9 ( a ) and 9 ( b ) are time charts for illustrating an operation of the CDMA communicating system 1 - 1 according to the first modification of the first embodiment of this invention, in which each of the MSs 1 A through 3 A is assumed to continuously transmit a remaining frame (up) 2 after transmitting a frame (up) 2 . As shown in FIG. 9 ( b ), each of the MSs 1 A through 3 A selects an access timing at which the remaining frame (up) 2 is transmitted in a different cycle T 1 - 5 , T 1 - 6 or T 1 - 7 set according to an order of acknowledge information for itself put in a frame (down) 3 , and transmits the remaining frame (up) 2 .

Hereinafter, an operation of the MS in the CDMA communicating system 1 - 1 according to the first modification of the first embodiment will be described with reference to time charts shown in FIGS. 9 ( a ) and 9 ( b ) and a flowchart shown in FIG. 10 .

In the CDMA communicating system 1 - 1 with the above structure according to the first modification of the first embodiment, each of the MSs 1 A through 3 A randomly selects an access timing among four access timings within a cycle when transmitting a frame (up) 2 to the BS 1 B.

Hereinafter, the description will be made on the assumption that the MA 1 A through 3 A transmit frames (up) 2 at access timings (t- 1 , t- 3 and t- 4 ) in cycle T 1 - 1 , respectively.

Each of the MSs 1 A through 3 A starts the timer after transmitting the frame (up) 2 (Step A 1 ).

When the BS 1 B confirms reception of frames (up) 2 transmitted from the MSs 1 A through 3 A, the BS 1 B puts acknowledge information for the MSs 1 A through 3 A in a frame (down) 3 in the order the BS 1 B received the frames (up) 2 .

Each of the MSs 1 A through 3 A receives in cycle T 1 - 3 the frame (down) 3 transmitted from the BS 1 B (Step A 2 ), and determines in cycle T 1 - 4 whether or not the received frame (down) 3 is in ACK mode and includes the same PID as its own PID having been transmitted (Step A 3 ).

If the frame (down) 3 received from the BS 1 B is not in ACK mode or does not include the same PID as its own PID having been transmitted, each of the MSs 1 A through 3 A determines whether or not the started timer is up (from NO route at Step A 3 to Step A 9 ). When the timer has counted up to the maximum value, the MS performs a re-transmitting process (from YES route at Step A 9 to Step A 10 ). When the timer does not yet count up to the maximum value, the MS moves to a process of receiving the frame (from NO route at Step A 9 to Step A 2 ).

When the PID having been transmitted is detected from the received frame (down) 3 , a count value of the timer is cleared.

When-the PID included in the frame (down) 3 coincides with its own PID transmitted, each of the MS 1 a through 3 A determines whether or not the MS has a remaining frame (up) 2 to be continuously transmitted (from YES route at Step A 3 to Step A 4 ). If not having a remaining frame (up) 2 , the MS completes the transmission (from NO route at Step A 4 to Step A 11 ).

When having a remaining frame (up) 2 , the MS detects a position (order) of the PID of its own among plural pieces of acknowledge information put in the received frame (down) 3 (from YES route at Step A 4 to according to an order of the detected PID (Step A 6 ), selects an access timing among four access timings in the set cycle, and sets the timing (Step A 7 ).

After that, each of the MS 1 A through 3 A transmits the remaining frame (up) 2 to the BS 1 B at the set access timing (Step A 8 ).

As shown in FIG. 9 ( b ), each of the MS 1 A through 3 A transmits a remaining frame (up) 2 to the BS 1 B according to an order [refer to FIG. 9 ( a )] of acknowledge information to a frame that itself has transmitted put in a frame (down) 3 received in cycle T 1 - 3 . The MS 1 A transmits a remaining frame (up) 2 at access timing t- 3 randomly selected within cycle T 1 - 5 , the MS 2 A transmits a remaining frame (up) 2 at access timing t- 1 randomly selected within cycle T 1 - 6 , and the MS 3 A transmits a remaining frame (up) 2 at access timing t- 4 randomly selected within cycle T 1 - 7 .

If the MS still has a remaining frame (up) 2 , processes similar to the above (Step A 1 through A 8 and Step A 9 through A 11 ) are performed.

In the CDMA communicating system of the first modification of the first embodiment has an advantage, in addition to that of the first embodiment. Namely, access timings at which the MSs 1 A through 3 A transmit remaining frames (up) 2 are not locally concentrated, but are set to, for example, different cycles so as to be distributed, as stated above. As shown in FIG. 9 ( b ), it is thereby possible to avoid conflict with access timings at which the MSs 6 A and 7 A have also accesses in cycle T 1 - 5 , thus further suppressing a decrease of the throughput.

(b3) Description of a Second Modification of the First Embodiment

According to a second modification of the first embodiment, the BS 1 B and the MSs 1 A through nA have similar functions to those described in the first embodiment. However, in a CDMA communicating system (denoted by a different reference character in order to discriminate it from the above CDMA communicating system 1 ) 1 - 2 according to the second modification, a frame (down) 3 in which plural pieces of acknowledge information rearranged in a predetermined order of priority are put is transmitted to a plurality of the MSs 1 A through nA, dissimilarly to the CDMA communicating system 1 according to the first embodiment.

Incidentally, like reference characters designate like or corresponding parts in the first embodiment.

To the above end, the BS 1 B rearranges plural pieces of acknowledge information to frames (up) 2 transmitted from the MSs 1 A through nA in a predetermined order of priority, puts the rearranged acknowledge information in a frame (down) 3 , and transmits the frame (down) 3 .

The BS 1 B determines the order of priority using, for example, continuation bits W [refer to FIG. 3 ( b )] in a received frame (up) 2 .

As an example of the order of priority, a frame having a frame (up) 2 to be continuously transmitted has a higher priority, while a frame without a frame to be continuously transmitted has a lower priority, as shown in Table 1 below.

The CPU 40 - 1 rearranges acknowledge information in such the order of priority.

Next, an operation of the CDMA communicating system 1 - 2 according to the second modification of the first embodiment will be described with reference to time charts shown in FIGS. 11 ( a ) and 11 ( b ), and FIG. 12 .

In the CDMA communicating system 1 - 2 with the above structure according to the second modification of the first embodiment, each of the MSs 1 A through nA selects an access timing among four access timings in a cycle when transmitting a frame (up) 2 .

The following description will be made on the assumption that the MS 1 A through 3 A transmit frames (up) 2 at different access timings (t- 1 , t- 3 and t- 4 ) wherein continuation bits W in the frame (up) 2 transmitted from the MS 1 A is “10”, continuation bits W in the frame (up) 2 transmitted from the MS 2 A is “01”, continuation bits W in the frame (up) 2 transmitted from the MS 3 A is “00”, and the BS 1 B receives the frames (up) 2 outputted from the MS 1 A through 3 A, puts acknowledge information in a frame (down) 3 and transmits the frame (down) 3 .

When the BS 1 B receives a frame (up) 2 (Step B 1 ), the BS 1 B performs CRC check, and determines whether or not a result of the CRC check is normal (Step B 2 ).

When a result of the CRC check is not normal, the BS 1 B determines whether or not now is a timing to transmit a frame (down) 3 (from NO route at Step B 2 to Step B 10 ).

If a result of the CRC check is normal, the BS 1 B detects continuation bits W (from YES route at Step B 2 to Step B 3 ).

After that, the BS 1 B determines whether or not there is a frame (up) 2 to be continuously received following the received frame (up) 2 on the basis of the detected continuation bits W (Step B 4 ). When there is not a frame (up) 2 to be continuously received, the BS 1 B sets the priority to “3” (from NO route at Step B 4 to Step B 8 ). For example, when continuation bits W in the received frame (up) 2 are “11” or “01”, the BS 1 B sets the priority to “3”.

When the BS 1 B determines that there is a frame (up) 2 to be continuously received, the BS 1 B further determines whether or not the received frame (up) 2 is a frame (up) 2 continuously received (from YES route at Step B 4 to Step B 5 ). When the received frame (up) 2 is a frame (up) 2 continuously received, the BS 1 B sets the priority to “1” (from YES route at Step B 5 to Step B 6 ). For example, when continuation bits W in the received frame (up) 2 are “00”, the BS 1 B sets the priority to “1”.

When the received frame (up) 2 is not a frame (up) 2 continuously received, the BS 1 B sets the priority to “2” (from NO route at Step B 5 to Step B 7 ) For example, continuation bits W in the received frame (up) 2 are “10”, the BS 1 B sets the priority to “2”.

The BS 1 B sets the priority of a frame (up) 2 transmitted from the BS 1 A to “2”, the priority of a frame (up) 2 transmitted from the MS 2 A to “3”, and a priority of a frame (up) 2 transmitted from the MS 3 A to “1”.

The BS 1 B stores the set priorities and PIDs (from any one of Step B 6 through B 8 to Step B 9 ), and determines whether or not now is a timing to transmit a frame (down) 3 (from NO route at Step B 2 or Step B 9 to Step B 10 )

When the BS 1 B determines that now is a timing to transmit a frame (down) 3 (when determined YES at Step B 10 ), the BS 1 B determines whether or not there is acknowledge information to be transmitted (from YES route at Step B 10 to Step B 11 ). When the BS 1 B determines that there is no acknowledge information to be transmitted, the BS 1 B repeats the above process (Steps B 1 through B 11 ) until determining that there is acknowledge information to be transmitted (until determined YES at Step B 11 ).

When there is acknowledge information to be transmitted, the BS 1 B rearranges plural pieces of acknowledge information to be put in the frame (down) 3 in a set order of priority (from YES route at Step B 11 to Step B 12 ), and transmits the frame (down) 3 (Step B 13 ).

For example, plural pieces of acknowledge information to the frames (up) 2 transmitted from the MSs 1 A through 3 A are rearranged in a set order of priority and put in the frame (down) 3 as shown in FIG. 11 ( a ), then transmitted.

After that, the BS 1 B clears information or the like on the stored priorities and the PIDs (Step B 14 ), and again performs a process such as a receiving process on a frame (up) 2 (Step B 1 ).

The MSs 1 A through 3 A perform a process shown in FIG. 8 to transmit, in cycle T 2 - 5 , remaining frames (up) 2 in the order the acknowledge information was put in the received frame (down) 3 .

The CDMA communicating system 1 - 2 according to the second modification of the first embodiment can attain similar effects to the CDMA communicating system 1 according to the first embodiment. In addition, it is possible to shorten an access time of the MS 3 A transmitting information. (transmitting a plurality of frames) having a high priority since the BS 1 B transmits a frame (down) 3 in which plural pieces of acknowledge information having been rearranged in the order of priority are put to the MSs 1 A through nA.

(b4) Description of a Third Modification of the First Embodiment

According to a third modification of the first embodiment, the BS 1 B and the MSs 1 A through nA-have similar functions to those described in the first embodiment. However, in a CDMA communicating system (denoted by a different reference character in order to discriminate it from the above CDMA communicating system 1 - 2 ) 1 - 3 , each of the MSs 1 A through nA transmits a remaining frame (up) 2 in a set period of transmit timings, dissimilarly to the CDMA communicating system 1 - 2 according to the above second modification of the first embodiment.

In the description on the third modification of the first embodiment, like reference characters designate like or corresponding parts in the second modification of the first embodiment.

To the above end, each of the MSs 1 A through nA receives acknowledge information to a transmitted frame (up) 2 , and transmits a remaining frame (up) 2 at a timing within a set period of access timings set according to an order of a piece of acknowledge information for itself put in a frame (down) 3 . Incidentally, plural pieces of acknowledge information put in the frame (down) 3 are rearranged in the order of priority shown in Table 1 by the BS 1 B.

For example, it is possible to set a period of access timings during which a remaining frame (up) 2 is transmitted to a different cycle according to an order of acknowledge information put in a frame (down) 3 . An access timing at which the remaining frame (up) 2 is transmitted is randomly selected among four access timings in each cycle.

Incidentally, the CPU 40 (refer to FIG. 4) sets or the like an access timing at which the remaining frame (up) 2 is transmitted.

Hereinafter, the following description will be made on the above assumption.

FIGS. 13 ( a ) and 13 ( b ) are time charts for illustrating an operation of the CDMA communicating system 1 - 2 according to the third modification of the first embodiment of this invention. Assuming that the MSs 1 A and 3 A continuously transmit remaining frames (up) 2 after the MSs 1 A through. 3 A transmit frames (up) 2 .

As shown in FIGS. 13 ( a ) and 13 ( b ), each of the MSs 1 A and 3 A selects an access timing to transmit a remaining frame (up) 2 within a different cycle T 3 - 5 or T 3 - 6 according to an order of acknowledge information put in a frame (down) 3 , and transmits the remaining frame (up) 2 .

In the CDMA communicating system 1 - 3 with the above structure according to the third modification of the first embodiment, each of the MSs 1 A through 3 A randomly selects an access timing among four access timings within a cycle when transmitting a frame (up) 2 to the BS 1 B, and transmits the frame (up) 2 .

Hereinafter, description will be made, with reference to a flowchart in FIG. 10, on the assumption that the MSs 1 A through 3 A transmit frames (up) 2 at different access timings (t- 1 , t- 3 and t 4 ) in cycle T 3 - 1 as shown in FIG. 13 ( b ).

Each of the MSs 1 A through 3 A starts the timer after transmitting a frame (up) 2 (Step A 1 ).

When the BS 1 B confirms reception of the frames (up) 2 transmitted from the MSs 1 A through 3 A, the BS 1 B transmits a frame (down) 3 in which acknowledge information for the MSs 1 A through 3 A rearranged in the order of priority shown in Table 1 is put. Here, continuation bits W of a frame (up) 2 transmitted from the MS 1 A are assumed to be “10”, continuation bits W of a frame (up) 2 transmitted from the MS 2 A are assumed to be “01”, and continuation bits W of a frame (up) 2 transmitted from the MS 3 A are assumed to be “00”.

The BS 1 B rearranges, on the basis of the continuation bits W, acknowledge information to the frames (up) to be put in the order of priority. The BS 1 B puts acknowledge information to the frames (up) 2 transmitted from the MSs 1 A and 2 A in a frame (down) 3 in the order the BS 1 B received the frames (up) 2 .

When putting acknowledge information to the frame (up) 2 transmitted from the MS 3 A in the frame (down) 3 , the BS 1 B rearranges the acknowledge information so as to put the acknowledge information to the frame (up) 2 transmitted from the MS 3 A ahead of the acknowledge information for the MSs 1 A and 2 A since the priority of the frame (up) 2 from the MS 3 A has a higher priority “1” than the priorities “2” and “3” of the acknowledge information having already put in the frame (down) 3 . When a timing to transmit the frame (down) 3 comes [for example, cycle T 3 -b shown in FIG. 13 ( a )], the BS 1 B transmits the frame (down) 3 .

Each of the MSs 1 A through 3 A receives, in cycle T 3 - 3 , the frame (down) 3 transmitted from the BS 1 B (Step A 2 ) and determines, in cycle T 3 - 4 , whether or not the received frame (down) 3 is in ACK mode and has the same PID as a PID having been transmitted (Step A 3 ).

When the frame received from the BS 1 B is not in ACK mode or has a PID different from a PID having been transmitted, the MS determines whether or not the started timer is up (from NO route at Step A 3 to Step A 9 ). When the timer has counted up to the maximum value, the MS performs a re-transmitting process (from YES route at Step A 9 to Step A 10 ). When the timer has not yet counted up, the MS moves to a process of receiving a frame (from NO route at Step A 9 to Step A 2 ).

Incidentally, a count value of the timer is cleared when a PID having been transmitted is detected from the received frame (down) 3 .

When the PID is the same as a PID having been transmitted, each of the MSs 1 A through 3 A determines whether or not there is a remaining frame (up) 2 to be continuously transmitted (from YES route at Step A 3 to Step A 4 ). If there is no remaining frame (up) 2 , the MS completes the transmission (from NO route at Step A 4 to Step A 11 ).

When there is a remaining frame (up) 2 , each of the MSs 1 A through 3 A detects a position (order) of its own PID among plural pieces of acknowledge information put in the received frame (down) 3 (from YES route at Step A 4 to Step A 5 ), sets a transmittable cycle according to an order of the detected PID (Step A 6 ), and selects an access timing among four access timings in the set cycle to set the same (Step A 7 ).

When the set access timing comes thereafter, each of the MSs 1 A through 3 A transmits a remaining frame (up) 2 to the BS 1 B (Step A 8 ).

As shown in FIG. 13 ( b ), the MSs 1 A and 3 A transmit remaining frames in the order [refer to FIG. 9 ( a )] plural pieces of acknowledge information to frames (up) 2 transmitted from themselves were put in the frame (down) 3 received in cycle T 3 - 3 . The MS 1 A transmits, in cycle T 3 - 6 , a remaining frame (up) 2 at an access timing randomly selected, while the MS 3 A transmits, in cycle T 3 - 5 , a remaining frame (up) 2 at an access timing randomly selected.

If there is still a remaining frame (up) 2 , processes similar-to the above. (Step A 1 through A 8 and Steps A 9 through A 11 ) are performed.

The CDMA communicating system 1 - 3 according to the third modification of the first embodiment achieves almost the same effects as the CDMA communicating system 1 - 2 according to the second modification of the first embodiment. In addition, access timings at which the MSs 1 A through 3 A transmit remaining frames (up) 2 are not locally concentrated, but distributed since the access timings are set in different cycles, for example. It is possible to avoid conflict with timings at which other MSs 6 A and 7 A access in cycle T 3 - 5 , as shown in FIG. 13 ( b ), which more suppresses a decrease of the throughput.

(b5) Description of a Fourth Modification of the First Embodiment

According to a fourth modification of the first embodiment, the BS 1 B and the MSs 1 A through nA have similar functions to those described in the first embodiment. However, in a CDMA communicating system (denoted by a different reference character in order to discriminate it from the above CDMA communicating system 1 ) 1 - 4 according to the fourth modification, when each of the MS 1 A through nA intending to transmit a frame (up) 2 receives a frame (down) 3 before initiate a random access, the MS delays a transmit timing by the number of pieces of acknowledge information put in the received frame (down) 3 and has a random access to the BS 1 B, dissimilarly to the CDMA communicating system 1 according to the first embodiment.

Incidentally, like reference characters designate like or corresponding parts in the first embodiments.

Each of the MSs 1 A through nA receives signals transmitted from the BS 1 B when transmitting a frame (up) 2 to determine whether or not the signals are a frame (down) 3 . When the signals are a frame (down) 3 , the each of the MS delays a transmit timing by the number of pieces of acknowledge information put in the frame (down) 3 , and transmits a frame (up) 2 to the BS 1 B.

The CPU 40 (refer to FIG. 4) sets a timing of a random access and the like on the basis of the received frame (down) 3 and the like when the MS transmits the first frame (up) 2 .

Next, an operation of the CDMA system 1 - 6 with the above structure according to the fourth modification of the first embodiment will be described with reference to time charts in FIGS. 14 ( a ) and 14 ( b ) and FIG. 15 .

The following description will be made on the assumption that the MSs 1 A through 3 A transmit frames (up) 2 at different access timings (t- 1 , t- 3 and t- 4 ) in cycle T 4 - 1 shown in FIG. 14 ( b ), the BS 1 B transmits in cycle T 4 -b a frame (down) 3 in which acknowledge information for the MSs 1 A through 3 A is put, and the MS 6 A randomly accesses in another cycle T 4 - 2 .

When there occurs a random access process in the MS 6 A in cycle T 4 - 2 (Step C 1 ), the MS 6 A receives a frame transmitted from the BS 1 B, to begin with (Step C 2 ).

The MS 6 A performs CRC check on the received frame to determine whether or not the CRC check is normal, besides determining whether or not the received frame is in ACK mode (Step C 3 ).

When the CRC check on the received frame is not normal or the received frame (down) is not in ACK mode, the MS 6 A initiates a random access (from NO route at Step C 3 to Step C 6 ). When the CRC check is normal and the received frame is in ACK mode [when the received frame is a frame (down) 3 ], the MS 6 A detects the number of put ACKs from the received frame (down) 3 (from YES route at Step C 3 to Step C 4 ), and sets a transmit timing so as to delay the transmit timing by the number of the put ACKs (Step C 5 ). When the set transmit timing comes, the MS 6 A starts a random access (Step C 6 ).

The MS 6 A receives a frame (down) 3 in cycle T 4 - 3 shown in FIG. 14 ( b ) (Step C 2 ), performs processes for confirmation on received contents and the like in cycle T 4 - 4 (Steps C 3 and C 4 ), delays a random access by the number of put ACKs (three) in cycle T 4 - 5 [denoted by T 4 d in FIG. 14 ( b )] since the number of put ACKs in the frame (down) 3 is “3”, and starts the random access at/after a timing denoted by T 4 s. Namely, the MS 6 A randomly selects a timing at/after timing T 4 s, and transmits a frame (up) 2 to the BS 1 B.

As above, the CDMA communicating system 1 - 4 according to the fourth modification of the first embodiment has the same effects as the above first embodiment. In addition, the MS 6 A receives a frame from the Bs 1 B before first randomly accessing to the base station, delays a transmit timing by the number of pieces of acknowledge information put in the received frame (down) 3 , and randomly accesses to the BS 1 B, so that conflict between the MS 6 A first accessing to the BS 1 B and the MSs 1 A and 2 A transmitting remaining frames (up) 2 is avoided, thus a decrease of a throughput of the system is more suppressed.

(b6) Description of a Fifth Modification of the First Embodiment.

According to a fifth modification of the first embodiment, the BS 1 B and the MSs 1 A through nA have similar functions to those described in the first embodiment. However, in a CDMA communicating system (denoted by a different reference character in order to discriminate it from the above CDMA communicating system 1 ) 1 - 5 according to the fifth modification, the BS 1 B puts the second ACK information showing the number of MSs intending to continuously transmit frames (up) 2 in a frame (down) 3 along with acknowledge information rearranged in a predetermined order of priority, and transmits the frame (down) 3 to the MSs 1 A through nA, while each of the MSs 1 A through nA transmitting a frame (up) 2 delays a transmit timing by the number of put ACKs shown by the second ACK information put in a received frame (down) 3 when receiving the frame (down) 3 before starting a random access, and has a random access to the BS 1 B, dissimilarly to the CDMA communicating system 1 according to the first embodiment.

Incidentally, like reference characters designate like or corresponding parts in the first embodiment.

The BS 1 B rearranges an order of acknowledge information to be put in a frame (down) 3 on the basis of continuation bits W [refer to FIG. 3 ( b )] put in the frames (up) 2 transmitted from the MSs 1 A through nA, puts the second ACK information showing the number of MSs intending to continuously transmit frames (up) 2 in the frame (down) 3 along with acknowledge information, and transmits the frame (down) 3 .

In the ACK format shown in FIG. 3 ( a ), it is possible to replace “NA” with the second ACK information “N” to configure the frame (down) 3 .

The following description will be made on the assumption that the BS 1 B transmits a frame (down) 3 in which “NA” is replaced with the second ACK information “N”, for example.

Incidentally, the CPU (refer to FIG. 5) 40 - 1 puts desired information such as the second ACK information and the like to be put in a frame (down) 3 on the basis of continuation bits W [refer to FIG. 3 ( b )] in a received frame (up) 2 .

When continuation bits put in a frame (up) 2 transmitted from each of the MSs 1 A through nA are in the bit structure shown in Table 1 above, for example, the BS 1 B sets the priority of the frames (up) 2 whose continuation bits W are “00” or “10” to “1” and counts up the number N of frames to be continuously transmitted, while setting the priority of the frames (up) 2 whose continuation bits W are “01” or “11” to “3”, and rearranging acknowledge information to be put in a frame (down) 3 in the order of priority.

The MSs 1 A through nA receives signals transmitted from the BS 1 B when transmitting a frame (up) 2 to determine whether or not the received frame is a frame (down) 3 . When the received frame is a frame (down) 3 , each of the MSs 1 A through nA delays a transmit timing by the number of pieces of acknowledge information put in the frame (down) 3 , and transmits the frame (up) 2 to the BS 1 B.

Incidentally, the CPU 40 (refer to FIG. 4) sets a timing or the like to transmit a frame (up) 2 to be first transmitted on the basis of the received frame (down) 3 .

Next, an operation of the CDMA communicating system 1 - 5 with the above structure according to the fifth modification of the first embodiment will be described with reference to time charts in FIGS. 16 ( a ) and 16 ( b ) and FIGS. 17 and 18.

The following description will be made on the assumption that the MSs 1 A through 3 A transmit frames (up) 2 at different access timings (t- 1 , t- 3 and t- 4 ) in cycle T 5 - 1 shown in FIG. 16 ( b ), the BS 1 B transmits in cycle T 5 -b a frame (down) 3 in which acknowledge information for the MSs 1 A through 3 A is put, and there occurs a random access by the MS 6 A in another cycle T 5 - 2 .

As shown in FIG. 18, when the BS 1 B starts a process of transmitting a frame (down) 3 (Step D 1 ), the BS 1 B clears the number “N” of MSs intending to transmit remaining frames (up) 2 (the second ACK information) so as to make it “0” (Step D 2 ).

When receiving a frame transmitted from each of the MSs 1 A through nA (Step D 3 ), the BS 1 B performs CRC check to determine whether or not a result of the CRC check is normal (Step D 4 ). When a result of the CRC check is not normal, the BS 1 B further determines whether or not now is a timing to transmit a frame (down) 3 (from NO route at Step D 4 to Step D 11 ).

When a result of the CRC check is normal, the BS 1 B detects continuation bits W from the received frame(up) 2 (from YES route at Step D 4 to Step D 5 ), and further determines whether or not there is a frame (up) 2 to be continuously received (Step D 6 ).

When the BS 1 B determines that there is not a frame (up) 2 to be continuously received, the BS 1 B sets the priority to “3” (from NO route at Step D 6 to Step D 9 ). When the BS 1 B determines that there is a frame (up) 2 to be continuously received, the BS 1 B counts up the number (N) of MSs intending to transmit remaining frames (up) 2 (from YES route at Step D 6 to Step D 7 ), sets the priority to “1” (Step D 8 ), and stores the priorities and PIDs thereof (Step D 8 or Step D 9 to Step D 10 ).

When continuation bits W in a frame (up) 2 transmitted from the MS 1 A in cycle T 5 - 1 are “00”, continuation bits W in a frame (up) 2 transmitted from the MS 2 A are “10” and continuation bits W in a frame (up) 2 transmitted from the MS 3 A are “11”, for example, the BS 1 B counts the second ACK information as “2”, and stores “2” and the priority of each frame (up) 2 .

The BS 1 B next determines whether or not now is a timing to transmit the frame (down) 3 (from NO route at Step D 4 or Step D 10 to Step D 11 ). When now is not a transmit timing, the BS 1 B repeats the above process (from NO route at Step D 11 to Step D 3 ) until a transmit timing comes (until determined YES at Step D 11 ).

The BS 1 B determines whether or not there is acknowledge information to be transmitted when determining that a transmit timing comes (from YES route at Step D 11 to Step D 12 ). When there is not acknowledge information to be transmitted, the BS 1 B repeats the above process (from NO route at Step D 12 to Step D 3 ) until determining that there is acknowledge information to be transmitted (until determined YES at Step D 12 ). When there is acknowledge information to be transmitted, the BS 1 B rearranges PIDs in the order of priority, puts the acknowledge information along with the second ACK information (N) in the frame (down) 3 (from YES route at Step D 12 to Step D 13 ), and transmits the frame (down) 3 (Step D 14 ) After transmitting the frame (down) 3 , the BS 1 B clears stored information on the priorities and the like (Step D 15 ).

For example, acknowledge information to the frames (up) 2 transmitted from the MSs 1 A through 3 A is rearranged in the order of priority as shown in FIG. 16 ( a ), and transmitted along with the second ACK information “N” in cycle T 5 -b.

To the contrary, when there occurs a random access process by the MS 6 A in cycle T 5 - 2 (Step E 1 ), the MS 6 A receives a frame transmitted from the BS 1 B (Step E 2 ), as shown in FIG. 17 .

The MS 6 A performs CRC check on the received frame to determine whether or not the CRC check is normal, and also determines whether or not the received frame is in ACK mode (Step E 3 ).

When the CRC check on the received frame is not normal or the received frame (down) is not in ACK mode, the MS 6 A starts a random access (from NO route at Step E 3 to Step E 6 ).

When the CRC check is normal and the received frame is in ACK mode [when the received frame is a frame (down) 3 ], the MS 6 A detects the second ACK information “N” from the received frame (down) 3 (from YES route at Step E 3 to Step E 4 ), and sets a transmit timing so as to delay the transmit timing by the second ACK information “N” (Step E 5 ). The MS 6 A then starts a random access when the set transmit timing comes (Step E 6 ).

The MS 6 A receives a frame (down) 3 in cycle T 5 - 3 shown in FIG. 16 ( b ) (Step E 2 ), performs processes of confirmation and the like on received contents in cycle T 5 - 4 (Steps E 3 and E 4 ), delays a random access by the second ACK information “N” [denoted as T 5 d in FIG. 16 ( b )] in cycle T 5 - 5 since the second ACK information “N” put in the frame (down) 3 is “2”, and starts the random access at/after timing T 5 s.

Namely, the MS 6 A randomly selects an access timing among timings after timing T 5 S, and transmits a frame (up) 2 to the BS 1 B.

The CDMA communicating system 1 - 5 according to the fifth modification of the first embodiment brings the similar effects to the CDMA communicating system 1 according to the first embodiment. In addition, the BS 1 B transmits a frame (down) 3 in which acknowledge information rearranged in a predetermined order of priority is put to the MSs 1 A through 3 A, so that an access time of the MS 1 A or the like transmitting information (a plurality of frames) is shortened.

Further, the BS 1 B puts the second ACK information “N” showing the number of MSs intending to transmit remaining information along with acknowledge information in a frame (down) 3 and transmits the frame (down) 3 to the MSs 1 A through nA, while the MS 6 A or the like receives the frame (down) 3 before randomly accessing in the first time to the BS 1 B, shifts a transmit timing by the number of “N” of the second ACK information put in the received frame (down) 3 and has a random access. Whereby, it is possible to avoid conflict between the MS 6 A first accessing to the BS 1 B and the MSs 1 A and 2 A continuously transmitting frames (up) 2 , which suppresses a decrease of the throughput.

(b7) Description of a Sixth Modification of the First Embodiment

According to a sixth modification of the first embodiment, the BS 1 B and the MS 1 A through nA have similar functions to those described in the first embodiment. However, in a CDMA communicating system (denoted by a different reference character in order to discriminate it from the above CDMA communicating system 1 - 2 ) 1 - 6 according to the sixth modification, when the number “M (M: an integer not less than 1)” of pieces of acknowledge information for MSs intending to continuously transmit frames (up) 2 among plural pieces of acknowledge information rearranged in the order of priority exceeds a maximum number 4 that is accessible in one cycle, excess acknowledge information is put in the next transmission frame (down) 3 and transmitted, dissimilarly to the CDMA communicating system 1 - 2 according to the second modification of the first embodiment.

Incidentally, like reference characters designate like or corresponding parts in the second modification of the first embodiment.

The BS 1 B determines priorities of acknowledge information to frames (up) 2 from the MSs 1 A through nA according to a predetermined order of priority, and counts the number “M” of pieces of acknowledge information for MSs intending to continuously transmit frames (up) 2 . When the counted number “M” exceeds “4”, the BS 1 B puts excess acknowledge information in the next frame (down) 3 and transmits the frame (down) 3 .

For example, when continuation bits W put in frames (up) 2 transmitted from the MSs 1 A through nA are in the bit structure shown in Table 1 above, the BS 1 B sets the priority of a frame (up) 2 whose continuation bits W are “00” or “10” to “1”, counts up the number “M” of MSs intending to continuously transmit frames (up) 2 , sets the priority of a frame (up) 2 whose continuation bits W are “01” or “11” to “3”, and rearranges the acknowledge information to be put in a frame (down) 3 in the order of priority.

The CPU 40 - 1 (refer to FIG. 5) rearranges acknowledge information in the order of preference.

Hereinafter, an operation of the CDMA communicating system 1 - 6 according to the sixth modification of the first embodiment will be described with reference to time charts shown in FIGS. 19 ( a ) and 19 ( b ) and FIG. 20 .

In the CDMA communicating system 1 - 6 with the above structure according to the sixth modification of the first embodiment, each of the MSs 1 A through nA selects an access timing among four access timings in a cycle when transmitting a frame (up) 2 , and transmits the frame (up) 2 at the selected timing.

The following description will be made on the assumption that the MSs 1 A through 7 A transmit frames (up) 2 at different access timings in cycles T 6 - 1 and T 6 - 2 shown in FIG. 19 ( b ), wherein continuation bits W of the frames (up) 2 transmitted from the MSs 1 A, 2 A, 4 A, 5 A and 7 A are “10”, while continuation bits W of the frames (up) 2 transmitted from the MSs 3 A and 6 A are “11”, and the BS 1 B receives the frames (up) 2 outputted from the MSs 1 A through 7 A, puts acknowledge information in one frame (down) 3 and transmits the frame (down) 3 .

After the BS 1 B starts a process of transmitting a frame (down) 3 (Step F 1 ), the BS 1 B updates the number “M” of MSs intending to continuously transmit frames (up) 2 to “0+m” (Step F 2 ). When receiving a frame (up) 2 (Step F 3 ), the BS 1 B performs CRC check and determines whether or not a result of the check is normal (Step F 4 ).

When a result of the check is not normal, the BS 1 B determines whether or not now is a timing to transmit a frame (down) 3 (from NO route at Step F 4 to Step F 11 ).

When a result of the CRC check is normal, the BS 1 B detects continuation bits W (from YES route at Step F 4 to Step F 5 ), and determines on the basis of the detected continuation bits W whether or not there is a frame (up) 2 to be continuously received (Step F 6 ).

When determining that there is not a frame (up) 2 to be continuously received, the BS 1 B sets the priority to “3” (from NO route at Step F 6 to Step F 9 ). To the contrary, when determining that there is a frame (up) 2 to be continuously received, the BS 1 B counts up the number “M” of MSs intending to continuously transmit frames (up) 2 (from YES route at Step F 6 to Step F 7 ), sets the priority to “1” (Step F 8 ), and stores the priority and a PID thereof (from Step F 8 or Step F 9 to Step F 10 ).

For example, since continuation bits W of frames transmitted from the MSs 1 A, 2 A, 4 A, 5 A and 7 A in cycles T 6 - 1 and T 6 - 2 are “10”, the BS 1 B counts the number “M” of MSs intending to continuously transmit frames (up) 2 as “5” when performing a process of putting acknowledge information to the frame (up) 2 transmitted from the MS 7 A.

The BS 1 B then determines whether or not now is a timing to transmit a frame (down) 3 . (from NO route at Step F 4 or Step F 10 to Step F 11 . When now is not a transmit timing, the BS 1 B repeats the above process (from NO route at Step F 11 to Step F 3 ) until a transmit timing comes (until determined YES at Step F 11 ).

When determining that now is a transmit timing, the BS 1 B further determines whether or not there is acknowledge information to be transmitted (from YES route at Step F 11 to Step F 12 ) When there is not acknowledge information, the BS 1 B repeats the above process (from NO route at Step F 12 to Step F 3 ) until determining that there is acknowledge information to be transmitted (until determined YES at Step F 12 ). When there is acknowledge information to be transmitted, the BS 1 B determines whether or not the number “M” of MSs intending to continuously transmit frames (up) 2 exceeds “4” (from YES route at Step F 12 to Step F 13 ).

When the number “M” of MSs intending to continuously transmit frames (up) 2 does not exceeds “4”, the BS 1 B rearranges the acknowledge information in the order of priority, and puts the acknowledge information in the current transmission frame (down) 3 (from NO route at Step F 13 to Step F 15 ) When the number “M” exceeds “4”, the BS 1 B stores the excess information along with “m (m=M−4)” in order to put acknowledge information for the excess MSs, separately from PIDs and the like for current transmission (from YES route at Step F 13 to Step F 14 ), and puts the acknowledge information in the order of priority in the current transmission frame (down) 3 to be now transmitted (from Step F 14 to Step F 15 ).

The BS 1 B transmits the frame (down) 3 (Step F 16 ), and clears the information stored for the current transmission (Step F 17 ). Meanwhile, after transmitting the frame (down) 3 , the BS 1 B performs a process and the like to update the number “M” of MSs intending to continuously transmit frames (up) 2 to “0+m” (from Step F 17 to Step F 2 )

For example, in a transmitting process in response to frames (up) 2 transmitted from the MSs 1 A through 7 A, acknowledge information for the MS 7 A that is an excess generated when the number “M” of MSs intending to continuously transmit frames (up) 2 exceeds “4” is not put in a frame (down) 3 transmitted at timing T 6 -b 1 in FIG. 19 ( a ), but separately stored, put in a frame (down) 3 transmitted in the next timing T 6 -b 2 and transmitted.

After transmitting the frame (down) 3 at timing T 6 -b 1 , the BS 1 B updates the number “5” of MSs intending to continuously transmit frames (up) 2 to “1” (from Step F 17 to Step F 2 ). When receiving a frame (up) 2 , the BS 1 B repeats similar processes to the above (Steps F 3 through F 10 ).

When a desired transmit timing comes (when determined YES at Step F 11 ), the BS 1 B determines the number of pieces of acknowledge information to frames ( 2 ) transmitted from the MS 7 A and the like to be put in a frame (down) 3 on the basis of the number “M” of MSs intending to continuously transmit frames (up) 2 (Steps F 13 and F 14 ), puts the acknowledge information in the order of priority in the frame (down) 3 , and transmits the frame (down) 3 (Steps F 15 through F 17 )

The MSs 1 A, 2 A, 4 A and 5 A receiving the frame (down) 3 transmitted at timing T 6 -b 1 in FIG. 19 ( a ) continuously transmit frames (up) 2 in cycle T 6 - 6 shown in FIG. 19 ( b ) in the order the acknowledge information rearranged in the order of priority in the BS 1 B was put when continuously transmitting the frames (up) 2 . The MS 7 A receives the frame (down) 3 transmitted at timing T 6 -b 2 in FIG. 19 ( a ), and continuously transmits a frame (up) 2 in cycle T 6 - 7 in FIG. 19 ( b ) according to an order of acknowledge information for itself rearranged in the order of priority in the BS 1 B.

As above, the CDMA communicating system 1 - 6 according to the sixth modification of the first embodiment brings the similar effects to the CDMA communicating system 1 - 2 according to the second modification. In addition, when the number “M” of pieces of acknowledge information for MSs intending to continuously transmit frames (up) 2 exceeds “4”, the BS 1 B transmits excess acknowledge information generated when the number “M” exceeds “4” at timing T 6 -b 2 in FIG. 19 ( a ). For example, acknowledge information, the number of pieces of which do not exceed the number of access timings in one cycle, for MSs intending to continuously transmit frames (up) 2 is put in a frame (down) 3 , the frame (down) 3 is transmitted at timing T 6 -b 1 in FIG. 19 ( a ), and another frame (down) 3 in which the excess acknowledge information for the MSs intending to continuously transmit frames (up) 2 is transmitted in the next timing. It is thereby possible to avoid conflict of accesses by MSs continuously transmitting frames at timing T 6 c in cycle T 6 - 7 in FIG. 19 ( b ), thus suppress a decrease of the throughput.

(b8) Description of a Seventh Modification of the First Embodiment

According to a seventh modification of the first embodiment, the BS 1 B and the MSs 1 A through nA have similar functions as those described in the first embodiment. However, in a CDMA communicating system (denoted by a different reference character in order to discriminate it from the above CDMA communicating system 1 ) 1 - 7 according to the seventh modification, spectrum spread signals obtained by using spreading codes in two systems are transmitted/received between the BS 1 B and the MSs 1 A through nA, dissimilarly to the CDMA communicating system 1 according to the first embodiment. Incidentally, like reference characters designate like or corresponding parts in the first embodiment.

Each of the terminals MS 1 A through nA uses either one of two types of spreading codes (#1 and #2). In addition, each of the MSs 1 A through nA continuously transmits a remaining frame (up) 2 according to an order of acknowledge information for a spreading code (#1 or #2) used by itself separately put in a frame (down) 3 .

Each of the terminals MSs 1 A through nA determines an order to transmit a remaining frame (up) 2 on the basis of number information “L” (hereinafter, referred to as the third ACK information) on acknowledge information for MSs having transmitted signals using a spreading code #1 to be described later put in a frame (down) 3 received from the BS 1 B. In concrete, the CPU 40 (refer to FIG. 4) makes the above determination.

The following description will be made on the assumption that the MSs 1 A and 4 A transmit spread spectrum signals obtained using the spreading code #1, while the MSs 2 A, 3 A and 5 A transmit spread spectrum signals obtained using a spreading code #2. Namely, the MSs 1 A and 4 A each configures a first terminal apparatus transmitting spread spectrum signals obtained using the spreading code #1 between two different types of spreading codes #1 and #2 to the BS 1 B, while the MSs 2 A, 3 A and 5 A each configures a second terminal apparatus transmitting spread spectrum signals obtained using the other spreading code #2 between two types of spreading codes #1 and #2 to the BS 1 B.

The BS 1 B separately puts acknowledge information for each of the spreading codes #1 and #2 in a frame (down) 3 along with the third ACK information “L”, and transmits the frame (down) 3 .

Incidentally, it is possible to replace “NA” with the third ACK information “L” in the ACK format shown in FIG. 3 ( a ), for example, to form a frame (down) 3 .

The BS 1 B receives spread spectrum signals obtained using the spreading codes #1 and #2 and performs a de-spreading process using the spreading codes #1 and #2 having desired phases. For this, the BS 1 B includes a plurality of de-spreading units 16 - 1 through 16 - 4 for each of the spreading codes #1 and #2, dissimilarly to the above receiving unit 10 - 1 (FIG. 5 ).

The following description will be made on the assumption that the BS 1 B transmits a frame (down) 3 in which “NA” is replaced with the third ACK information “L”.

To the above end, the BS 1 B separately counts the numbers “L” and “P” of pieces of acknowledge information for respective spreading codes #1 and #2 and holds the numbers when putting the acknowledge information to frames (up) 2 transmitted using the spreading codes #1 and #2.

The CPU 40 - 1 (refer to FIG. 5) performs the above counting for each of the spreading codes #1 and #2, or a process of putting acknowledge information in a frame (down) 3 .

Next, an operation of the CDMA communicating system 1 - 7 according to the seventh modification of the first embodiment will be described with reference to time charts in FIGS. 21 ( a ) and 21 ( b ), and FIGS. 22 and 23.

In the CDMA communicating system 1 - 7 having the above structure according to the seventh modification of the first embodiment, each of the MSs 1 A through nA selects an access timing among four access timings in a cycle when transmitting a frame (up) 2 , and transmits the frame (up) 2 at the selected timing.

The following description will be made on the assumption that, in cycle T 7 - 1 shown in FIG. 21 ( b ), the MSs 1 A and 4 A transmit frames (up) 2 using the spreading code #1 having different phases at different access timings, while the MSs 2 A, 3 A and 5 A transmit frames (up) 2 using the spreading code #2 having different phases at different access timings, and the BS 1 B receives the frames (up) 2 outputted from the MSs 1 A through 5 A, and performs a process of putting acknowledge information in a frame (down) 3 to transmit the same.

Each of the MSs 1 A through 5 A starts the timer after transmitting a frame (up) 2 (Step G 1 in FIG. 22 ).

As shown in FIG. 23, after the BS 1 B starts a process of transmitting a frame (down) 3 (Step H 1 ), the BS 1 B clears count values of “L” and “P” (step H 2 )

When the BS 1 B receives a frame (up) 2 of the spreading code #1 (Step H 3 ), the BS 1 B performs CRC check, and determines whether or not a result of the check is normal (Step H 4 ).

When a result of the CRC check on the received frame (up) 2 is not normal, the BS 1 B determines whether or not now is a timing to transmit acknowledge information (from NO route at Step H 4 to Step H 11 ). When a result of the CRC check is normal, the BS 1 B counts up the number information “L” (the third ACK information) on acknowledge information for MSs having transmitted signals using the spreading code #1 (from YES route at Step H 4 to Step H 5 ), stores PIDs for the spreading code #1 (Step H 6 ), and determines whether or not now is a timing to transmit acknowledge information (Step H 11 ).

When the BS 1 B receives a frame (up) 2 of the spreading code #2 (Step H 7 ), the BS 1 B performs CRC check, and determines whether or not a result of the check is normal (Step H 8 ).

When a result of the CRC check on the received frame (up) 2 is not normal, the BS 1 B determines whether or not now is a timing to transmit acknowledge information (from NO route at Step H 8 to Step H 11 ). When a result of the CRC check on the received frame (up) 2 is normal, the BS 1 B counts up number information “P” on acknowledge information for MSs having transmitted signals using the spreading code #2 (from YES route at Step H 8 to Step H 9 ), stores PIDs for the spreading code #2 (Step H 10 ), and determines whether or not now is a timing to transmit the acknowledge information (Step H 11 ).

When now is not a timing to transmit the acknowledge information, the BS 1 B repeats the above process (Steps H 3 through H 6 or Steps H 7 through H 10 ) until determining that now is a timing to transmit the acknowledge information (until determined YES at Step H 11 ).

When now is a timing to transmit the acknowledge information, the BS 1 B determines whether or not a count value of “L” or “P” is larger than “0” (from YES route at Step H 11 to Step H 12 ). When counts of “L” and “P” are both “0”, the BS 1 B repeats the above process (from NO route at Step H 12 to Step H 3 or H 7 ).

When a count of “L” or “P” is larger than “0”, the BS 1 B arranges first acknowledge information for the code #1 in the lead (from YES route at Step H 12 to Step H 13 ), then arranges acknowledge information for the code #2 following the acknowledge information for the code #1 (Step H 14 ), and puts the acknowledge information along with the third ACK information “L” in a frame (down) 3 (Step H 15 ).

After that, the BS 1 B transmits the frame (down) 3 (Step H 16 ), and clears information used to put the acknowledge information and the like in the frame (down) 3 (Step H 17 ).

Thereafter, the BS 1 B performs the above process whenever receiving a frame (up) 2 (from Step H 17 to Step H 2 ).

As shown in FIG. 21 ( a ), for example, the BS 1 B first arranges acknowledge information for the MSs 1 A and 4 A having transmitted using the spreading code #1 in the lead, secondary separately arranges acknowledge information for the MSs 2 A, 3 A and 5 A having transmitted signals using the spreading code #2 in order, and puts the acknowledge information in a frame (down) 3 along with the third ACK information “L” (=2) showing the number of pieces of acknowledge information for the MSs 1 A and 4 A having transmitted signals using the spreading code #1. The BS 1 B transmits the frame (down) 3 when a desired transmit timing comes [timing T 7 -b in FIG. 21 ( a ), for example] and the timer is started (Step G 2 ).

Each of the MSs 1 A through 5 A receives the frame (down) 3 transmitted from the BS 1 B in cycle T 7 -b (Step G 3 ) and determines in cycle T 7 - 4 whether or not the frame (down) 3 is in ACK mode and has the same PID as a PID having been transmitted from itself (Step G 4 )

When the frame received from the BS 1 B is not in ACK mode or the PID does not coincide with the PID having been transmitted, the MS determines whether or not the started timer is up (from NO route at Step G 4 to Step G 5 ). When the timer has counted up to the maximum value, the MS performs a re-transmitting process (from YES route at Step G 5 to Step G 6 ). When the timer is not up, the MS moves to a process of receiving a frame (from NO route at Step G 5 to Step G 3 ).

Incidentally, a count value of the timer is cleared when a transmitted PID is detected from a received frame (down) 3 .

When the PID is the same as the PID having been transmitted, each of the MSs 1 A through 5 A determines whether or not there is a remaining frame (up) 2 to be continuously transmitted (from YES route at Step G 4 to Step G 7 ) When there is not a remaining frame (up) 2 , the MS completes the transmission (from NO route at Step G 7 to Step G 13 ).

When there is a remaining frame (up) 2 , each of the MSs 1 A through 5 A detects a position of a PID of its own among plural pieces of acknowledge information and the third ACK information “L” put in the received frame (down) 3 (from YES route at Step G 7 to Step G 8 ).

Each of the MSs 1 A through 5 A then determines whether or not itself has transmitted using the code #1 (Step G 9 ). If the MS has transmitted the frame (up) 2 using the code #1, the MS sets a timing to continuously transmit the remaining frame (up) 2 according to an order of acknowledge information for itself put in the frame (down) 3 (from YES route at Step G 9 to Step G 10 ).

If the MS has transmitted using the code #2, each of the MSs 2 A, 3 A and 5 A, for example, sets a timing to transmit a remaining frame (up) 2 to be continuously transmitted using the third ACK information “L” (from NO route at Step G 9 to Step G 11 ). Namely, each of the MSs 2 A, 3 A and 5 A neglects acknowledge information corresponding to a value of the third ACK information put in the frame received from the BS 1 B, and sets a timing to transmit a frame (up) 2 to be continuously transmitted according to an order of put acknowledge information for itself.

Each of the MSs 1 A through 5 A transmits spread spectrum signals obtained using the code (#1 or #2) when a desired access timing set comes (Step G 12 ).

In FIG. 21 ( b ), the MSs 1 A and 4 A spectrum-spread remaining frames (up) 2 using the spreading code #1 having different phases, and transmit the frames (up) 2 at access timings in cycle T 7 - 5 in the order acknowledge information was put in a received frame (down) 3 . The MSs 2 A, 3 A and 5 A spectrum-spread remaining frames (up) 2 using the spreading code #2 having different phases, and transmit the frames (up) 2 at access timings in the order acknowledge information other than acknowledge information corresponding to the third ACK information “L” (=2) was put in the received frame (down) 3 .

After that, each of the MSs 1 A through 5 A performs the above process on a frame (up) 2 to be continuously transmitted (Step G 12 to Step G 2 ).

In the CDMA communicating system 1 - 7 according to the seventh modification of the first embodiment, the BS 1 B puts the third ACK information “L” along with acknowledge information in a frame (down) 3 and transmits the same, so that each of the MSs 1 A through 5 A finds a position of acknowledge information to a frame (up) 2 having been transmitted from itself using its own spreading code (#1 or #2) among plural pieces of acknowledge information put in the frame (down) 3 on the basis of the third ACK information “L”. It is thereby possible to avoid conflict of access timings at which remaining frames (up) 2 are continuously transmitted even in the CDMA communication using two types of spreading codes (#1 and #2), thus suppress a decrease of the throughput.

(b9) Others

As having been described the present invention, the present invention is not limited to the above examples, but may be modified in various ways without departing from the scope of the invention.