Abstract:
A system for wireless communication is provided that includes a mobile switching center and a communication component, such as a base station or an access network. The mobile switching center is operable to transmit a message identifying a mobile station to be released. The communications component is operable to receive the message from the mobile switching center. The communications component is further operable to identify and release the mobile station based on the message.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY 
     The present invention is related to that disclosed in U.S. Provisional Patent Application Ser. No. 60/651,577 filed Feb. 10, 2005 entitled “Mobile Release Message”. U.S. Provisional Patent Application Ser. No. 60/651,577 is assigned to the assignee of the present application. The subject matter disclosed in U.S. Provisional Patent Application Ser. No. 60/651,577 is hereby incorporated by reference into the present disclosure as if fully set forth herein. The present invention hereby claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 60/651,577. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     FIELD OF THE INVENTION 
     The present disclosure relates to mobile telephony. More specifically, but not by way of limitation, a method and system are provided that allow a connectionless mobile release message to be sent from a mobile switching center to release a mobile station. 
     BACKGROUND OF THE INVENTION 
     Among the components typically present in a mobile telephony system are a mobile switching center (MSC), a base station or access network, and a mobile station. The mobile station is a mobile telephone, handset or mobile telecommunications device user by a subscriber to a mobile telephony service to place and receive calls via the mobile telephony service. The base station contains the fixed equipment with which multiple mobile stations can communicate. In situations where data rather than voice communication is being transmitted, the term ‘access network’ might be used to refer to and describe the equipment that performs functions similar to those performed by a base station. The MSC acts as a switching point that connects multiple base stations to the public switched telephone network, to mobile telephony-based networks, or to other networks. The communication link between a mobile station and a base station can be referred to as a traffic channel. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a system for wireless communication is provided that includes a mobile switching center and a communication component, such as a base station or an access network. The mobile switching center is operable to transmit a message identifying a mobile station to be released. The communications component is operable to receive the message from the mobile switching center. The communications component is further operable to identify and release the mobile station based on the message. 
     In another embodiment, a method for instructing a communications component to release a mobile station is provided. The method includes a mobile switching center sending a message to the communications component. The communications component receives the message from the mobile switching center and determines, from information in the message, which mobile station the message applies to. The communications component releases the mobile station in response to receiving the message. 
     In another embodiment, a message is provided for a mobile switching center to instruct a system, such as a base station or an access network, to release a mobile station. The message includes a header section, a mobile identity section and a cause section. The mobile identity section contains information for the system to identify the mobile station the system is to release in response to receiving the message. The cause section contains information related to the message. 
     These and other features and advantages will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the presentation and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings in detailed description, wherein like reference numerals represent like parts. 
         FIG. 1  illustrates an early traffic channel scenario for a mobile release message according to an embodiment of the present disclosure. 
         FIG. 2  illustrates a paging scenario for a mobile release message according to an embodiment of the present disclosure. 
         FIG. 3  illustrates an inter-technology page scenario for a mobile release message according to an embodiment of the present disclosure. 
         FIG. 4  illustrates a mobile release message according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     It should be understood at the outset that although an exemplary implementation of one embodiment of the present invention is illustrated below, the present system may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should in no way be limited to the exemplary implementations, drawings, and techniques illustrated below, including the exemplary design and implementation illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents. 
     When a communication link is established between a mobile station and a base station, the base station (or access network depending upon whether the traffic is data or voice) assigns a dedicated traffic channel to the link. At any one time, a single base station might maintain a separate traffic channel for each of multiple mobile stations with which it is communicating. For voice calls, at the same time that the base station assigns a traffic channel to a mobile station, the base station establishes a dedicated signaling link to the MSC. For each traffic channel between a mobile station and the base station, there is a corresponding dedicated signaling link to the MSC. Therefore, when the MSC and the base station communicate on a specific signaling link, it is implied that the communication relates to the corresponding base station-mobile station traffic channel. 
     This arrangement is illustrated in  FIG. 1 . An MSC  10  is in communication with a base station  20 , which is in communication with a plurality of mobile stations. In this embodiment, a first mobile station  30 , a second mobile station  32 , and a third mobile station  34  are present, but in other embodiments other numbers of mobile stations could be present. The base station  20  communicates with mobile station  30  over a first traffic channel  40 , with mobile station  32  over a second traffic channel  42 , and with mobile station  34  over a third traffic channel  44 . The base station  20  communicates with the MSC  10  over a first dedicated signaling link  50 , a second dedicated signaling link  52 , and a third dedicated signaling link  54 . 
     Traffic channel  40  in this example correlates with dedicated signaling link  50 . Therefore, when the MSC  10  communicates with the base station  20  via signaling link  50  it is implied that this communication relates to the first mobile station  30  communicating with base station  20  on traffic channel  40 . Similarly, traffic channel  42  in this example correlates to dedicated signaling link  52 . When the MSC  10  communicates with the base station  20  via signaling link  52  it implies that the communication relates to the second mobile station  32  communicating with base station  20  on traffic channel  42 . Traffic channel  44  correlates to dedicated signaling link  54 . When the MSC  10  communicates with the base station  20  via signaling link  54  it implies that the communication relates to the third mobile station  34  communicating with base station  20  on traffic channel  44 . 
     A message sent from the MSC  10  to a mobile station  30 ,  32 , or  34  over a particular traffic channel/dedicated signaling link combination does not necessarily contain information identifying the mobile station  30 ,  32 , or  34  to which the message is to be sent. Instead, the base station  20  can determine the mobile station  30 ,  32 , or  34  to which the message is to be sent by identifying the traffic channel/dedicated signaling link combination on which the message has been placed. Since each traffic channel/dedicated signaling link combination is associated with a single mobile station  30 ,  32 , or  34 , identifying the traffic channel/dedicated signaling link combination on which a message has been placed identifies the mobile station  30 ,  32 , or  34  for which the message is intended. 
     Under existing technology, if the MSC  10  wanted to cease communication between the base station  20  and a mobile station, mobile station  30  for example, the MSC  10  would send what is known as a Clear Command to the base station  20  via signaling link  50 . The base station  20  would identify that the Clear Command, received on signaling link  50 , relates to traffic channel  40  and would cease communication with mobile station  30 . The Telecommunications Industry Association&#39;s standard TIA-2001-C, “Interoperability Specification for CDMA2000 Access Network Interfaces”, specifies that the Clear Command is to be sent over a dedicated signaling link, such as dedicated signaling link  50 . Since the Clear Command does not contain information identifying a particular mobile station, the base station must use the signaling link to determine which mobile station should be released. In some situations however, described in more detail below, the dedicated signaling link  50  between the MSC  10  and the base station  20  might not be present. If it is desired to have the base station  20  cease attempting to communicate with the mobile station  30  in such situations, a Clear Command could not be used because a dedicated signaling link over which the Clear Command could be sent has not yet been established. 
     In one embodiment, the present disclosure provides a message or mobile release message that is sent from an MSC to a base station to tell the base station to release a mobile station. The mobile release message is referred to as connectionless in the sense that it can be sent from an MSC to a base station without the need of a dedicated connection, such as signaling link  50 , between the MSC and the base station. 
     As used herein, the expression ‘releasing a mobile station’ and the like can refer to disconnecting a traffic channel that has already been established, ceasing to attempt to establish a traffic channel that has not yet been established, or ceasing to transmit data on a traffic channel to which a mobile station has been connected. Also, when a mobile release message is said to be sent to a base station, it should be understood that the mobile release message could equivalently be sent to an access network or other similarly functioning systems. 
       FIG. 1  may be used to illustrate one of the scenarios in which a mobile release message might be used. In this case, which can be referred to as an early traffic channel assignment scenario, a traffic channel gets established before a corresponding dedicated signaling link is established. For example, traffic channel  40  might be established before dedicated signaling link  50  is established. If the traffic channel  40  became unnecessary, e.g., if it were determined that the base station  20  is connected to an incorrect mobile station  30 , it might be desirable to release the mobile station  30  before the dedicated signaling link  50  is established. Under existing technology, a Clear Command could not be used to accomplish the release because a dedicated signaling link would not exist over which the Clear Command must be sent to identify the particular mobile station. According to one embodiment, the present disclosure provides a mobile release message that may be used in this instance to release the mobile station  30 . The mobile release message includes an identifier or information used by the base station  20  to identify the mobile station  30 . The mobile release message may be communicated from the MSC  10  to the base station  20  on a communication channel absent a related signaling link. The mobile release message identifies the mobile station  30  to be released. The base station  20  then releases the communication between the base station  20  and the mobile station  30 . 
       FIG. 2  illustrates another scenario in which a mobile release message might be used. In this case, which can be referred to as a paging scenario, an MSC  10  is attempting to establish communication with a mobile station  30 . The MSC  10  sends pages to several base stations asking the base stations to attempt to locate the mobile station  30 . For example, the MSC  10  might send page  60  to a first base station  20 , page  62  to a second base station  22 , and page  64  to a third base station  24 . While three base stations are shown in this embodiment, in other embodiments other numbers of base stations could be present. 
     If base station  20  locates the mobile station  30 , a traffic channel  40  might be established between the mobile station  30  and the base station  20  and a dedicated signaling link  50  might be established between the base station  20  and the MSC  10 . Base station  22  and base station  24  would not necessarily be aware that base station  20  has located the mobile station  30  and might continue to attempt to locate the mobile station  30 . 
     It is inefficient for the second and third base stations  22  and  24  to continue to attempt to locate the mobile station  30  since it has already been located by the first base station  20 . It might be desirable to instruct the second and third base stations  22  and  24  to stop searching for the mobile station  30 . Such an instruction could not be conveyed by a Clear Command because the dedicated signaling links, as discussed above, over which the Clear Command could be transmitted and understood by the base stations would not have been established between the MSC  10  and the second base station  22  or between the MSC  10  and third base station  24 . In this case, a mobile release message including information identifying the mobile station  30  to which the message relates may be sent from the MSC  10  to the second base station  22  and the third base station  24 . The second and third base stations  22  and  24  identify that the message relates to mobile station  30  and then stop attempting to locate the mobile station  30 . 
       FIG. 3  illustrates yet another scenario in which a mobile release message might be used. In this case, which can be referred to as an inter-technology page scenario, an MSC  10  is capable of communicating with multiple networks, such as a high-speed data-based 1xEV-DO network  70  and a voice-based 3G1x CDMA network  80 . The 1xEV-DO network  70  includes an access network (AN) component  90 . The AN  90  performs a similar function to the base stations described above. However, since the AN  90  is in a data-based, rather than voice-based, network, the AN  90  might use different technology than the base stations. 
     The MSC  10  communicates with the AN  90  via communication path  100 , which may be a different type of communication link than the dedicated signaling links described above. Dedicated signaling links are typically used for voice calls and, since there is typically no voice communication in a 1xEV-DO network  70 , dedicated signaling links are not used to communicate with a 1xEV-DO network  70 . Instead, the MSC  10  and the AN  90  communicate using connectionless messages. The AN  90  communicates information to the mobile station  30  over a communication path  110  that is similar to the traffic channel  40  between a base station  20  and a mobile station  30 , as discussed above. 
     In this scenario example, the AN  90  might be transmitting data to the mobile station  30  via path  110 . During this data transmission, a voice call is placed to the mobile station  30  from another party. The voice call is communicated by the MSC  10  sending a page over signaling link  100  to the AN  90 , which delivers this message to the mobile station  30  via traffic channel  110 . The mobile station  30  identifies that a voice call has been received, and the user of the mobile station  30  chooses whether to accept the voice call. If the user accepts the voice call, the mobile station  30  then ceases accepting data from the AN  90  and would accept the voice call transmitted from the MSC  10  by establishing a traffic channel  40  with the base station  20 . In other words, the mobile station  30  would switch from being a component of the data-based 1xEV-DO network  70  to being a component of the voice-based 3G1x CDMA network  80 . 
     In such a case, the AN  90  would typically not be aware that the mobile station  30  was no longer accepting data from the AN  90  and would continue to attempt to transmit data to the mobile station  30 . Since attempting to transmit data to a component that is not accepting data can be inefficient, it might be desirable for the MSC  10  to be able to instruct the AN  90  to stop attempting to transmit data to the mobile station  30  when the mobile station  30  switches from the data-based 1xEV-DO network  70  to the voice-based 3G1x CDMA network  80 . 
     As discussed above, such an instruction cannot be sent via a Clear Command from the MSC  10  to the AN  90  because a Clear Command can be sent only over a dedicated signaling link and a dedicated signaling link was never established between the MSC  10  and the AN  90 . Under the current systems, the base stations or AN  90  continue to attempt to establish communication with the mobile station  30  until, for example, the communication times out. The mobile release message of the present disclosure is more efficient and can be sent from the MSC  10  to the AN  90  instructing the AN  90  to stop attempting to transmit data to the mobile station  30 . Again the mobile release message includes information to identify the mobile station  30 , so that the AN  90  may cease communicating or attempting to communicate with the mobile station  30 . 
     In each of the three scenarios described above, a mobile release message is used to release a mobile station. In an embodiment, the mobile release message follows the format used by other types of messages in the TIA-2001-C standard. An example of the format of a typical mobile release message is shown in  FIG. 4 . It should be understood that this figure is an example only and that other messages, message formats, or types may be used to convey similar information. 
     In this embodiment, the mobile release message  120  consists of a series of octets of data in three main sections: a header  130 , a mobile identity  140 , and a cause  150 . In  FIG. 4 , the octets in each section are numbered in an octet column  160  and the bytes in each octet are numbered in a byte row  170 . For example, bytes  0  through  7  of octet  2  of the header section  130  contain ‘Length Indicator (LI)=&lt;variable&gt;’, bytes  0  through  2  of octet  3  of the mobile identity section  140  contain ‘Type of Identity=[ 101  (ESN),  110  (IMSI)]’, etc. 
     The header section  130  contains information about the message  120  and is a typical feature of messages that follow the TIA-2001-C standard. Components of the header section  130  can include a message discrimination record, a length indicator record, and a message type record. The message type record might contain a code identifying the message as a mobile release message  120 . The message type record might also indicate whether the mobile release message  120  applies to an early traffic channel scenario, a paging scenario, or an inter-technology page scenario or this information may be communicated in the cause code, which is discussed below. 
     The mobile identity section  140  identifies the mobile station to which the mobile release message  120  is to be sent. As mentioned previously, a message sent over a dedicated signaling link to a mobile station does not necessarily contain information identifying the mobile station to which the message is being sent since the base station can determine the mobile station to which the message is being sent by identifying the dedicated signaling link on which the message has been placed. When a dedicated signaling link is not present, as is the case when a mobile release message  120  is sent, some other means of identifying the mobile station to which the mobile release message  120  applies is needed. This information is provided in the mobile identity section  140  of the mobile release message  120 . The mobile identity section  140  may contain any information that may be used by one or more of the base station  20  and/or AN  90  to identify the mobile station  30 . 
     There are two general protocols for identifying a mobile station: through an electronic serial number, or ESN, or through an international mobile serial identifier, or IMSI. A mobile station will be identified by one or the other of these protocols, but not both. In an embodiment, bytes  0  through  2  of octet  3  of the mobile identity section  140  of a mobile release message  120  specify whether the mobile station to which a mobile release message  120  applies follows the ESN protocol or the IMSI protocol. The structure of the mobile identity section  140  differs depending on which protocol is followed. 
     If the mobile station to which a mobile release message  120  applies follows the ESN protocol, identity information about the mobile station is contained in sub-section  180  of the mobile release message  120 . If the mobile station to which a mobile release message  120  applies follows the IMSI protocol, identity information about the mobile station is contained in sub-section  190  of the mobile release message  120 . That is, either sub-section  180  or sub-section  190 , but not both, of the mobile identity section  140  will be present depending on which protocol is used to identify the mobile station to which the mobile release message  120  is being sent. 
     The cause section  150  of a mobile release message  120  is a typical feature of messages that follow the TIA-2001-C standard. It contains a cause code that specifies other information such as the reason that an MSC is attempting to instruct a base station to release a mobile station. Additional information related to or describing the mobile release message or reasons for it being transmitted may be included in this section of the message. 
     While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein, but may be modified within the scope of the appended claims along with their full scope of equivalents. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented. 
     Also, techniques, systems, subsystems and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as directly coupled or communicating with each other may be coupled through some interface or device, such that the items may no longer be considered directly coupled to each other but may still be indirectly coupled and in communication, whether electrically, mechanically, or otherwise with one another. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.