Communication repeater system and method

This application is upon and claims the benefit of priority from Japanese Patent Application No. 2017-085717, filed Apr. 24, 2017, the entire contents of which are incorporated herein by reference.

Embodiments described herein relate generally to a communication repeater system and method.

Radio transmission schemes, including frequency division duplexing (FDD) and time division duplexing (TOD), for mobile communication terminal devices such as mobile phones and smartphones are known. FDD employs two different frequency bands as a pair of a downlink signal and an uplink signal while TOD employs a downlink signal and an uplink signal in the same frequency band by time division.

A shared repeater system is also known in which service providers (carriers: communication service providers) share a repeater system (communication repeater system) for enabling use of mobile communication terminal devices in dead cones including indoors.

The FDD radio transmission requires a certain frequency interval (gap) between a downlink frequency band and an uplink frequency band. In recent years, the use of the TDD radio transmission scheme has been increasing due to tightness of available frequencies.

Thus, an increase in the number of devices by the TDD radio transmission scheme in the shared repeater system is expected.

In the shared repeater system adopting the TDD radio transmission, variations in time-division timing in adjacent bands among different service providers may cause mutual interference and deterioration in service quality or stop of service.

It is an object of the present invention to provide a communication repeater system and method which can reduce variations in time-division timing among different service providers and ensure improvements in service quality and continuity of service.

FIG. 1 is a schematic configuration block diagram of a communication repeater system according to an embodiment;

FIG. 2 is an explanatory diagram of a connection between a master station device and radio frequency units (RFUs) in a first mode;

FIG. 3 is an explanatory diagram of a time synchronization process according to precision time protocol (PTP);

FIG. 4 is a flowchart of a transmission/reception switching timing setting process;

FIG. 5 is a first explanatory diagram of a connection between a master station device, and slave station devices and RFUs in a second mode;

FIG. 6 is a second explanatory diagram of a connection between a master station device, and slave station devices and RFUs in the second mode; and

FIG. 7 is a third explanatory diagram of a connection between a master station device, and slave station devices and RFUs in the second mode.

In general, according to one embodiment, a communication repeater system includes a master station device, a plurality of slave station devices, and a plurality of radio frequency units which converts a signal from each of base station systems into an optical digital signal and transmit the optical digital signal to the master station device. The base station systems establish communication by time-division duplex scheme. The communication repeater system repeats communication between a mobile communication terminal device and each of the base station system via a corresponding one of the slave station devices.

The radio frequency units each include a detector that detects each of transmission and reception switching timings between the master station device and each of the radio frequency units.

Meanwhile, the slave station devices each include a setter that sets reference transmission and reception switching timing on the basis of acquired reference time information.

The radio frequency units each include a corrector that corrects a variation in the transmission and reception switching timings in accordance with the reference transmission and reception switching timing.

Next, exemplary embodiments will be described in detail with reference to the appended drawings.

FIG. 1 is a schematic configuration block diagram of communication system including a communication repeater system according to an embodiment.

A communication system 10 includes base station systems 11 - 1 to 11 - 7 , a communication repeater system 20 , antennas ANT 1 to ANT 8 , mobile communication terminal devices 16 - 1 to 16 - 7 , as illustrated in FIG. 1 .

The communication repeater system 20 includes radio frequency units (hereinafter referred to “RFUs”) 12 - 1 to 12 - 6 , a master station device 13 , and slave station devices 14 - 1 to 14 - 8 .

Next, a configuration of the communication system 10 will be described in detail.

First, a configuration of each of the base station systems 11 - 1 to 11 - 7 will be described.

The base station system 11 - 1 includes a grand master clock (GMC) unit 21 - 1 that receives a global navigation satellite system (GNSS) signal from a GNSS and outputs reference time data DST 1 and a base station device (represented by BS in FIG. 1 ) 22 - 1 that controls communication on the basis of the reference time data DST 1 via a radio frequency communication signal SC 1 in a carrier frequency band f 1 .

The base station system 11 - 2 includes a grand master clock (GMC) unit 1 - 2 that receives a GNSS signal and outputs reference time data DST 2 , and a base station device 22 - 2 that controls communication on the basis of the reference time data DST 2 via a radio frequency communication signal SC 2 in the carrier frequency band f 1 .

The base station system 11 - 3 includes a grand master clock (GMC) unit 21 - 3 that receives a GNSS signal and outputs reference time data DST 3 , and a base station device 22 - 3 that controls communication on the basis of the reference time data DST 3 via a radio frequency communication signal SC 3 in a carrier frequency band f 2 .

The base station system 11 - 4 includes a grand master clock (GMC) unit 21 - 4 that receives a GNSS signal and outputs reference time data DST 4 , and a base station device 22 - 4 that controls communication on the basis of the reference time data DST 4 via a radio frequency communication signal SC 4 in the carrier frequency band f 2 .

The base station system 11 - 5 includes a grand master clock (GMC) unit 21 - 5 that receives a GNSS signal and outputs reference time data DST 5 , and a base station device 22 - 5 that controls communication on the basis of the reference time data DST 5 via a radio frequency communication signal SC 5 in the carrier frequency band f 1 .

The base station system 11 - 6 includes a grand master clock (GMC) unit 21 - 6 that receives a GNSS signal and outputs reference time data DST 6 , and a base station device 22 - 6 that controls communication on the basis of the reference time data DST 6 via a radio frequency communication signal SC 6 in a carrier frequency band f 3 .

The base station system 11 - 7 includes a grand master clock (GMC) unit 21 - 7 that receives a GNSS signal and outputs reference time data DST 7 , and a base station device 22 - 7 that controls communication on the basis of the reference time data DST 7 via a radio frequency communication signal SC 7 in the carrier frequency band f 3 .

Next, a configuration of the communication repeater system 20 will be described.

First, the RFUs 12 - 1 to 12 - 6 of the communication repeater system 20 will be described.

The RFU 12 - 1 receives radio frequency communication signals SC 1 corresponding to mobile communication terminal devices from the base station system 11 - 1 via communication cables such as coaxial cables. Then, the RFU 12 - 1 multiplexes the radio frequency communication signals SC 1 into a digital signal SLD 1 and transmits the digital signal SLD 1 to the master station device 13 via an optical cable LC 1 .

The RFU 12 - 2 receives radio frequency communication signals SC 2 corresponding to mobile communication terminal devices from the base station system 11 - 2 via communication cables such as coaxial cables. Then, the RFU 12 - 2 multiplexes the radio frequency communication signals SC 2 into an optical digital signal SLD 2 and transmits the optical digital signal SLD 2 to the master station device 13 via an optical cable LC 2 .

Further, the RFU 12 - 2 receives radio frequency communication signals SC 3 corresponding to mobile communication terminal devices from the base station system 11 - 3 via communication cables such as coaxial cables. Then, the RFU 12 - 2 multiplexes the radio frequency communication signals SC 3 into an optical digital signal SLD 3 and transmits the optical digital signal SLD 3 to the master station device 13 via the optical cable LC 3 .

The RFU 12 - 3 receives radio frequency communication signals SC 4 corresponding to mobile communication terminal devices from the base station system 11 - 4 via communication cables such as coaxial cables. Then, the RFU 12 - 3 multiplexes the radio frequency communication signals SC 4 into an optical digital signal SLD 4 and transmits the optical digital signal SLD 4 to the master station device 13 via the optical cable LC 4 .

The RFU 12 - 4 receives radio frequency communication signals SC 5 corresponding to mobile communication terminal devices from the base station system 11 - 5 via communication cables such as coaxial cables. Then, the RFU 12 - 4 multiplexes the radio frequency communication signals SC 5 into an optical digital signal SLD 5 and transmits the optical digital signal SLD 5 to the master station device 13 via the optical cable LC 5 .

The RFU 12 - 5 receives radio frequency communication signals SC 6 corresponding to mobile communication terminal devices from the base station system 11 - 6 via communication cables such as coaxial cables. Then, the RFU 12 - 5 multiplexes the radio frequency communication signals SC 6 into an optical digital signal SLD 6 and transmits the optical digital signal SLD 6 to the master station device 13 via the optical cable LC 6 .

The RFU 12 - 6 receives radio frequency communication signals SC 7 corresponding to mobile communication terminal devices from the base station system 11 - 7 via communication cables such as coaxial cables. Then, the RFU 12 - 6 multiplexes the radio frequency communication signals SC 7 into an optical digital signal SLD 7 and transmits the optical digital signal SLD 7 to the master station device 13 via the optical cable LC 7 .

Next, the slave station devices 14 - 1 to 14 - 8 of the communication repeater system 20 will be described.

The slave station device 14 - 1 includes a sub unit (represented by SUB in FIG. 1 ) 15 - 1 that communicates the mobile communication terminal device via the antenna unit ANT 1 in the carrier frequency band f 1 and a sub unit 15 - 2 that communicates with the mobile communication terminal device via the antenna unit ANT 1 in the carrier frequency band f 2 .

The slave station device 14 - 2 includes a sub unit 15 - 3 that communicates with the mobile communication terminal device via the antenna unit ANT 2 in the carrier frequency band f 1 and a sub unit 15 - 4 that communicates with the mobile communication terminal device via the antenna unit ANT 2 in the carrier frequency band f 2 .

The slave station device 14 - 3 includes a sub unit 15 - 5 that communicates with the mobile communication terminal device via the antenna unit ANT 3 in the carrier frequency band f 1 and a sub unit 15 - 6 that communicates with the mobile communication terminal device via the antenna unit ANT 3 in the carrier frequency band f 3 .

The slave station device 14 - 4 includes a sub unit 15 - 7 that communicates with the mobile communication terminal device via the antenna unit ANT 4 in the carrier frequency band f 1 .

The slave station device 14 - 5 includes a sub unit 15 - 8 that communicates with the mobile communication terminal device via the antenna unit ANT 2 in the carrier frequency band f 1 and a sub unit 15 - 9 that communicates with the mobile communication terminal device via the antenna unit ANT 5 in the carrier frequency band f 2 .

The slave station device 14 - 6 includes a sub unit 15 - 10 that communicates with the mobile communication terminal device via the antenna unit ANT 6 in the carrier frequency band f 1 , a sub unit 15 - 11 that communicates with the mobile communication terminal device via the antenna unit ANT 6 in the carrier frequency band f 2 , and a sub unit 15 - 12 that communicates with the mobile communication terminal device via the antenna unit ANT 6 in the carrier frequency band f 3 .

The slave station device 14 - 7 includes a sub unit 15 - 13 that communicates with the mobile communication terminal device via the antenna unit ANT 7 in the carrier frequency band f 2 .

The slave station device 14 - 8 includes a sub unit 15 - 14 that communicates with the mobile communication terminal device via the antenna unit ANT 7 in the carrier frequency band f 3 .

Next, the master station device 13 of the communication repeater system 20 will be described.

The master station device 13 corrects differences in delay among the service providers being the RFUs 12 - 1 to 12 - 6 and differences in delay among the slave station devices 14 - 1 to 14 - 8 , to reduce variations in effective transmission/reception switching timing (time division duplex (TDD) timing) of the antenna units ANT 1 to ANT 7 . This is because in the above communication repeater system 20 , the antenna units ANT 1 to ANT 8 are disposed in the area that transmission and reception waves can interfere with each other, so that the variations in the transmission/reception switching timings among the service providers cause the transmission and reception waves to mutually interfere, making proper communication unfeasible.

In view of this, in the present embodiment, the master station device 13 detects and adjusts the variations in the transmission/reception switching timing to thereby prevent the transmission/reception waves from mutually interfering due to the variations in the transmission/reception switching timings of the antenna units ANT 1 to ANT 8 .

This can greatly reduce the load on the slave station devices 14 - 1 to 14 - 8 from when the slave station devices 14 - 1 to 14 - 8 alone prevent mutual interference between the transmission and reception waves, leading to reducing system building costs and system operation costs.

The causes of the variations in the TDD timing will be described.

The causes of the variations in the TDD timing include (1) differences in delay among the service providers and (2) differences in delay among the slave station devices.

For example, the following five examples of differences in delay among the service providers are assumed:

(1.1) Variations in the grand master clock (GMC: reference clock) due to individual differences among the GMC units 21 - 1 to 21 - 6 of the respective service providers;

(1.2) Differences in (processing) delay due to individual differences among the base station devices 22 - 1 to 22 - 7 of the respective service providers;

(1.3) Differences in (transmission) delay due to differences in signal line lengths between the base station devices 22 - 1 to 22 - 7 of the respective service providers and the corresponding RFUs 12 - 1 to 12 - 6 ;

(1.4) Differences in (processing) delay due to individual differences among detector circuits of the respective RFUs 12 - 1 to 12 - 6 ; and

(1.5) Differences in (transmission) delay due to differences in cable lengths between each of the RFUs 12 - 1 to 12 - 6 and the master station device 13 .

The following two examples of differences in delay among the slave station devices are assumed:

(2.1) Differences in (transmission) delay due to a difference in cable lengths of optical cables between each of the slave station devices 14 - 1 to 14 - 8 and the master station device 13 ; and

(2.2) Differences in (processing) delay due to individual differences among the respective slave station devices 14 - 1 to 14 - 8 .

Among the causes of the variations in the TDD timing, the differences in delay among the slave station devices in the item (2) are corrected by various conventional methods. The differences in delay among the service providers will be thus described below.

From the master station device 13 's point of view, the differences in delay among the service providers are considered as effective delay occurring between each of the RFUs 12 - 1 to 12 - 6 and the master station device 13 . That is, delay (variation) occurring between each of the RFU 12 - 1 to 12 - 6 and the master station device 13 needs to be corrected.

When at least one of the slave station devices 14 - 1 to 14 - 8 has absolute reference timing (timing signal), different modes are assumable depending on whether the master station device 13 and the RFUs 12 - 1 to have absolute reference timing (timing signal).

The following two modes will be exemplified:

(1) First mode: the master station device 13 and all the RFUs 12 - 1 to 12 - 6 have absolute reference timing (timing signal); and

(2) Second mode: at least one of the slave station devices 14 - 1 to 14 - 8 has absolute reference timing (timing signal).

A configuration and an operation of the communication repeater system 20 will be described below in order of the modes.

(1) The master station device 13 and all the RFUs 12 - 1 to 12 - 6 have absolute reference timing (timing signal).

In this case, it is assumed that the master station device 13 and all the RFUs 12 - 1 to 12 - 6 are provided with connected to) one of a global positioning system (GPS) receiver, a GMC unit, a terrestrial digital tuner, and an atomic clock.

Alternatively, at least one of the RFUs 12 - 1 to 6 or at least one of the slave station devices 14 - 1 to 14 - 8 may be provided with one of the GPS receiver, the GMC unit, the terrestrial digital tuner, and the atomic clock, and the other devices are compliant with precision time protocol (PTP) specified in IEEE 1588.

Herein, assumed that the slave station device 14 - 1 is connected to the GMC unit, and the master station device 13 and all of the RFUs 12 - 1 to 12 - 6 are compliant with the PTP specified in IEEE 1588, time synchronization process will be described by way of example.

The PTP is a protocol for synchronizing time among the devices connected to a local area network (LAN). In this example, the master station device 13 and the RFUs 1 to 12 - 6 are connected via the optical cables LC 1 to LC 6 , and the master station device 13 and the slave station devices 14 - 1 to 14 - 8 are connected via the optical cables (group) LCG 1 to LCG 8 , to function as a LAN as a whole.

In this case, it is necessary for the master station device 13 to synchronize time with the RFUs 12 - 1 to 12 - 6 and the base station systems 11 - 1 to 11 - 7 as a whole. The time synchronization between the RFU 12 - 1 and the master station device under the control of the slave station device 14 - 1 will be first described.

FIG. 2 is an explanatory diagram of a connection between the master station device, and the slave station devices and the RFUs in the first mode.

To synchronize time between the master station device 13 and the RFU 12 - 1 , the slave station device 14 - 1 and the master station device 13 both have a function of correcting time information transmitted from a GMC unit 25 as a boundary clock (BC) via a LAN 26 and redelivering the corrected time information to the RFU 12 - 1 .

In the PTP, the GMC unit 25 functions as a master for the slave station device 14 - 1 functioning as a slave.

Further, in the PTP, the slave station device 14 - 1 functions as a master for the master station device 13 , the master station device 13 functions as a master for the RFU 12 - 1 , and the RFU 12 - 1 function as a slave.

FIG. 3 is an explanatory diagram of a time synchronization process according to the PTP. In this case, the master station device 13 merely corrects the time information of the slave station device 14 - 1 being a higher-level device, and redelivers the corrected time information to the RFU 12 - 1 being a lower-level device, therefore, the operations between the slave station device 14 - 1 and the RFU 12 - 1 alone will be described for better understanding.

At time t 0 , the slave station device 14 - 1 transmits to the RFU 12 - 1 an announce message AM for notification of time synchronization accuracy information.

Thereby, the RFU 12 - 1 knows that it will receive the time synchronization accuracy information within a predetermined period of time after the transmission of the announce message AM.

At time t 1 , the slave station device 14 - 1 transmits a sync message SM to the RFU 12 - 1 as an event message.

In this case, the time t 1 being the transmission time of the sync message SM recorded in the sync message SM.

At time t 2 , upon receiving the sync message SM, the RFU 12 - 1 records reception time t 2 .

At time t 3 , the RFU 12 - 1 transmits a delay request message DRM to the slave station device 14 - 1 to notify it of the receipt of the sync message SM.

In this case, the time t 3 being the transmission time of the delay request message DRM is recorded in the delay request message DRM.

At time t 4 , upon receiving the delay request message DRM, the slave station device 14 - 1 records reception time t 4 .

Further, the slave station device 14 - 1 transmits a delay response message DRPM containing the reception time t 4 of the delay request message DRM to the RFU 12 - 1 .

Next, a time difference calculation method in the above situation will be described.

It is assumed that the time of a clock of the RFU 12 - 1 and the time of a clock of the slave station device 14 - 1 are offset by an offset time TOF 1 .

In the above example, with transmission delay time DLY 1 unchanged, a time difference from the slave station device 14 - 1 (master) to the RFU 12 - 1 (slave) and a time difference from the RFU 12 - 1 (slave) to the slave station device 14 - 1 (master) satisfy the following relations.

The time difference from the slave station device 14 - 1 (master) to the RFU 12 - 1 (slave)

t 2 −t 1 =DLY 1 +TOF 1  (1)

The time difference from the RFU 12 - 1 (slave) to the slave station device 14 - 1 (master)

t 4 −t 3 =DLY 1 TOF 1  (2)

As a result, the NFU 12 - 1 calculates the transmission delay time DLY 1 from the sum of Formulas (1) and (2) and calculates the offset time TOF 1 from the difference between Formulas (1) and (2).

That is,

DLY 1=(( t 2 −t 1)+( t 4 −t 3))/2  (3)

TOF 1=(( t 2 −t 1)−( t 4 −t 3))/2  (4)

Similarly, the RFU 12 - 2 calculates an offset time TOF 2 and a transmission delay time DLY 2 corresponding to the slave station device 14 - 1 . The RFU 12 - 3 calculates an offset time TOF 3 and a transmission delay time DLY 3 corresponding to the slave station device 14 - 1 . The RFU 12 - 4 calculates an offset time TOF 4 and a transmission delay time DLY 4 corresponding to the slave station device 14 - 1 . The RFU 12 - 5 calculates an offset time TOF 5 and a transmission delay time DLY 5 corresponding to the slave station device 14 - 1 . The RFU 12 - 6 calculates an offset time TOF 6 and a transmission delay time DLY 6 corresponding to the slave station device 14 - 1 .

Thus, the RFUs 12 - 1 to 12 - 6 constantly correct time on the basis of the calculated transmission delay times DLY 1 to DLY 6 and the offset times TOF 1 to TOF 6 , respectively, implementing accurate time synchronization.

Next, transmission/reception switching timing setting will be described.

FIG. 4 is a flowchart of a transmission/reception switching timing setting process.

First, the slave station device 14 - 1 detects the transmission/reception switching timing for each service provider (for each RFU in this example) (Step S 11 ).

Then, the slave station device 14 - 1 determines whether the transmission/reception switching timings corresponding to all the service providers have been detected (Step S 12 ).

When determining in Step S 12 that the transmission/reception switching timings of all the service providers have not been detected yet (Step 12 ; No), the slave station device 14 - 1 returns to Step S 11 and repeats the process.

When determining in Step S 12 that the transmission/reception switching timings of all the service providers have been detected (Step S 12 ; Yes), the slave station device 14 - 1 selects a service provider having the latest transmission/reception switching timing among the service providers as subjects of the selection (Step S 13 ).

Then, the slave station device 14 - 1 determines whether differences in the transmission/reception switching timings between the ted service provider and the other service providers are a predetermined threshold time or more (Step S 14 ).

Herein, the predetermined threshold time is defined as a period of time set for detecting anomaly in the transmission/reception switching timing caused by a failure of a timer (clock) that the service provider concerned uses for acquiring time information. In other words, the predetermined threshold time is used for excluding unlikely transmission/reception switching timings, considering the expected accuracy of the timer.

When in Step S 14 the differences in the transmission/reception switching timings between the selected service provider and the other service providers are determined to be the predetermined threshold time or more, the transmission/reception switching timing of the selected service provider cannot be adopted in terms of reliability, therefore, the slave station device 14 - 1 excludes the selected service provider from the subjects of the selection (Step S 16 ), returns to Step S 13 again, and subjects the remaining service providers to the above processing.

When determining in Step S 14 that the differences in the transmission/reception switching timings between the selected service provider and the other service providers are less than the predetermined threshold time (Step S 14 ; No), the slave station device 14 - 1 sets (while the time synchronization is established), as reference transmission/reception switching timing, the transmission/reception switching timing of the selected service provider, that is, any of the normal transmission/reception switching timings between the slave station device 14 - 1 and the RFUs 12 - 1 to 12 - 6 (for example, the latest transmission/reception switching timing), notifies the RFUs 12 - 1 to 12 - 6 of the reference transmission/reception switching timing, and ends the process (Step S 15 ).

Thereby, the RFUs 12 - 1 to 12 - 6 correct the variations in the transmission/reception switching timing on the basis of the synchronized time, in accordance with the reference transmission/reception switching timing to switch transmission and reception at the reference transmission/reception switching timing.

Transmission and reception can be thus switched in synchronization with any of the transmission/reception switching timings between the slave station device 14 - 1 and the RFUs 12 - 1 to 12 - 6 , which enables reduction in the variations in the time-division timing among the different service providers and ensures an improvement in the service quality and the continuity of the service.

(2) Only the slave station device 14 - 1 has absolute reference timing (timing signal).

In this case, for example, only the slave station device 14 - 1 as provided with (or connected to) one of the GPS receiver, the GMC unit, the terrestrial digital tuner, and the atomic clock, and all of the RFUs 12 - 1 to 12 - 6 are not compliant with the PTP specified in the IEEE 1586.

FIG. 5 is an explanatory diagram of a connection between the master station device and the RFUs in the second mode.

In this case, the slave station device 14 - 1 acquires the absolute reference timing from a GPS unit 31 , and concurrently transmits reference timing signals St 0 to the master station device 13 and the RFUs 12 to 12 - 6 in association with the acquired absolute reference timing.

As a result, upon receiving the reference timing signals via the master station device 13 , the RFUs 12 - 1 to 12 - 6 can correct the transmission/reception switching timing according to the transmission line lengths of the corresponding optical cable LCG 1 , the master station device 13 , and the corresponding optical cables LC 1 to LC 6 , and a processing delay time of the master station device 13 to attain no effective differences in delay (or differences within a predetermined allowable range) thereamong.

Further, as with the item (1), the RFUs 1 to 12 - 6 correct, under the established time synchronization, the variations in the transmission/reception switching timing in accordance with the reference transmission/reception switching timing to switch transmission and reception at the reference transmission/reception switching timing being the latest one of the transmission/reception switching timings between the slave station device 14 - 1 and the RFUs 12 - 1 to 12 - 6 . This can reduce the variations in the time-division timing among the different service providers, and ensure an improvement in service quality and the continuity of the service.

In the above, the GMC unit is connected to the slave station device 14 - 1 , however, the same process is feasible by the master station device to or at least one of the RFUs 12 - 1 to 12 - 6 provided with (or connected to) one of the GPS unit 31 (see FIG. 5 ), a terrestrial digital tuner 35 (see FIG. 6 ), and an atomic clock 37 (see FIG. 7 ) on the basis of the absolute reference timing (time information: timing signal) obtained from the device.

The master station device 13 and the slave station devices 14 - 1 to 14 - 8 of the present embodiment each include a control device such as a CPU, a storage such as a read only memory (ROM) or a RAM, and an external storage such as an HUD or a CD drive device, and have a hardware configuration of a general computer.

Programs executed by the master station device 13 , the slave station devices 14 - 1 to 14 - 8 , or the RFUs 12 - 1 to 12 - 6 of the present embodiment are recorded and provided in installable or executable file format on a computer readable recording medium including a CD-ROM, a DVD, or a USB memory.

The programs executed by the master station device 13 , the slave station devices 14 - 1 to 14 - 8 , or the RFUs 12 - 1 to 12 - 6 of the present embodiment may be stored on a computer connected to a network such as the Internet and downloaded via the network. Programs executed by the communication repeater system of the present embodiment may be provided or distributed via a network such as the Internet.

The programs of the communication repeater device of the present embodiment may be incorporated into a ROM in advance, for example.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.