Mobile cellular network selection from wireless LAN

This application claims benefit of priority to U.S. Ser. No. 60/460,631, filed Apr. 4, 2003, the disclosure of which is incorporated herein by reference.

1. Technical Field

The present invention relates to a system for Public Land Mobile Networks (PLMN)/network selection using a single standard Service Set Identification (SSID).

2. Background

The selection of a network is required specifically where a Wireless Local Access Network (WLAN) is connected to multiple Public Land Mobile Networks (PLMN) and the roaming mobile subscriber selects the preferred visited PLMN. Hence, it is also expected that the mobile subscriber contains a list of preferred roaming partners.

A number of solutions have been proposed. One solution was to format the Service Set Identification (SSID) such that a single PLMN can be advertised by an SSID. Since standard Access Points (APs) only support a single SSID, an AP using this solution can advertise only one PLMN. The second solution was based on modifying the AP and WLAN air interface standard, the outcome of which is uncertain.

It therefore is of interest to develop methods for PLMN/network selection using a single standard SSID.

Methods are provided to enable a mobile subscriber of a Wireless Local Access Network (WLAN) connected to multiple PLMN to make a selection from among the connections available using a single standard SSID. The methods include addition of the Mobile Country Code (MCC) to the SSID; addition of an MCC and several Mobile Network Codes (MNC) to the SSID; and a reverse Domain Name Server (DNS) lookup for the gateway IP address through the designated DNS server.

FIG. 1 shows a layout of the bits in an SSID which includes a Mobile Country Code (MCC).

FIG. 2 shows a layout of the bits in an SSID which includes both a Mobile Country Code (MCC) and a series of Mobile Network Codes (MNC).

FIG. 3 shows a layout of the bits in a HostInfo field string which includes both a Mobile Country Code (MCC) and a series of Mobile Network Codes (MNC).

The first embodiment of the invention is the addition of a Mobile Country Code (MCC) to an SSID. A WLAN can be connected to multiple PLMNs. The mobile client is assumed to have a list of preferred PLMNs for some countries (home and/or visited). In every country, there are few PLMN operators (maybe up to 15). In this first embodiment, it is proposed that a short country code be included somewhere in the SSID of the WLAN APs (see FIG. 1 ). This country code will help the mobile client speed up the process of finding the preferred PLMN. The mobile client will identify the preferred and present PLMN by “trying connection” to each PLMN in its preferred list for the given country (discovered earlier). “Try connection” can be as simple as an attempt for standard DNS name resolution. If the connection attempt to a preferred PLMN fails, the mobile client will try next most preferred PLMN in its preference list for that country. This solution will have the least impact on the SSID present in the WLAN.

The second embodiment is the inclusion of an MCC and an MNC in an SSID. One Mobile Country Code (MCC) and a series of Mobile Network Codes (MNC) may be included in an SSID. The MCC will identify the country and has a length of 3 digits or 12 bits. Each MNC represents the well-known identification for the PLMN connected to the WLAN, and has a length of 2 to 3 digits or up to 12 bits. As an example, if 73 bits are reserved for the WLAN name, then we can accommodate up to 15 PLMN ids on a single standard SSID (see FIG. 2 ). Once the mobile client has selected the preferred PLMN, it would perform the required procedures to pass its data traffic through the selected PLMN.

The third embodiment is to make no change to the SSID. The SSID can be left intact as desired. Following authentication, the mobile client will obtain an IP address and gateway IP address. The mobile client will try a reverse Domain Name Server (DNS) lookup for the gateway IP address through the designated DNS server. The local DNS server can be configured to return a domain name which could be used for querying DNS again to request for the HostInfo field (HINFO). The HINFO is composed of two strings (RFC 1034). Such strings can be used to list Mobile Country Code (MCC) and the Mobile Network Codes (MNCs) of all the connected PLMNs to the WLAN as shown in FIG. 3 .

As shown in FIG. 3 , it would only takes 24 octet (character) to represent 15 PLMN operators.

All publications and patent applications mentioned in this specification are indicative of the level if skill of those in the art to which this invention pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

The invention now having been fully described, it will be apparent to one of ordinary skill in the art than many changes and modifications can be made thereto without departing from the spirit or scope of the appended claims.