Abstract:
A wireless communication network generally includes a number of subscriber units, a base station controller, and a base station transceiver coupled to the base station controller. A parameter specifying an interval at which subscriber units in the wireless communication network are permitted to generate autonomous messages is stored, for example, in a system parameter database at the base station. The parameter is broadcast by the base station transceiver over-the-air to subscriber units in the wireless communication network. In response to receipt of the parameter, the subscriber units store the parameter and thereafter transmit autonomous message over-the-air only in accordance with the parameter. In one preferred embodiment, the parameter regulates how often autonomous messages can be transmitted by individual subscriber units. Alternatively or additionally, the parameter can be used to ensure that the subscriber unit is in a stable state before an autonomous message is transmitted by preventing transmission of autonomous messages while the subscriber unit is generating messages at too rapid of a rate.

Description:
This application claims the benefit of Provisional application Ser. No. 60/162,323, filed Oct. 28, 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates in general to wireless communication and, in particular, to the utilization of access channels in a wireless communication network. Still more particularly, the present invention relates to a method and system for regulating autonomous messaging by subscriber units in a wireless communication network. 
     2. Description of the Related Art 
     In cellular telephone networks, one widely utilized communication technology is CDMA (Code Division Multiple Access). CDMA is a spread spectrum technology that distributes the signal of interest (e.g., a voice or data signal) over a wide radio frequency spectrum. CDMA can be implemented with any of a number of air interface standards, including the cellular IS-95A and IS-2000 standards and the PCS (Personal Communications Services) ANSI J-STD-008 standard. Each of these standards defines two groups of channels, the forward channel and the reverse channel. 
     The forward channel, which communicates voice and data from the cell to mobile stations, carries traffic, a pilot signal, and overhead information. The pilot and overhead channels establish system timing and station identity. The pilot channel also is employed as a signal strength reference in the handoff process, which transfers communication with a mobile station to another base station in the wireless communication network. The reverse channel, which communicates voice and data from the mobile station to the cell, carries both traffic and signaling. Any particular reverse channel is active only during calls or signaling by or to the associated mobile station. 
     In the reverse channel, the channels utilized for signaling, that is, carrying control messages, from the mobile stations to the cell are referred to generically as access channels. Some access channels are available for use by all mobile stations (i.e., are shared access channels), while some are dedicated for use by particular mobile stations. Examples of control messages carried by the access channels include Origination Messages that initiate calls, Page Response Messages that provide responses to pages, Registration Messages that provide information regarding the locations and identities of mobile stations, and Flash With Information Messages that alert the cell to changes in the hook states of mobiles. 
     In conventional CDMA networks, mobile stations have been permitted to send autonomous messages, which are defined herein as control messages originated by a mobile station that are not prompted by a specific request by the cell, via the shared access channels in an uncontrolled manner. This lack of regulation can lead to excessive autonomous messaging, for example, by a malfunctioning mobile station. Excessive autonomous messaging may also result from a poor choice of system parameters that require a mobile station to provide too many control messages, poor cell boundary planning that causes a mobile station to repeatedly re-register with a base station as the mobile user traverses the cell boundary, or simply user error. Excessive autonomous messaging can consume the limited bandwidth of shared access channels, resulting in mobile users experiencing access delays, access failures, or even service outages. 
     SUMMARY OF THE INVENTION 
     In view of the problems that may result from unregulated autonomous messaging, the present invention provides a method and system for regulating autonomous messaging by subscriber units (e.g., mobile stations) in a wireless communication network. A wireless communication network in accordance with the present invention generally includes a number of subscriber units, a base station controller, and a base station transceiver coupled to the base station controller. A parameter specifying an interval at which subscriber units in the wireless communication network are permitted to generate autonomous messages is stored, for example, in a system parameter database at the base station. The parameter is broadcast by the base station transceiver over-the-air to subscriber units in the wireless communication network. In response to receipt of the parameter, the subscriber units store the parameter and thereafter transmit autonomous message over-the-air only in accordance with the parameter. In one preferred embodiment, the parameter regulates how often autonomous messages can be transmitted by individual subscriber units. Alternatively or additionally, the parameter can be used to ensure that the subscriber unit is in a stable state before an autonomous message is transmitted by preventing transmission of autonomous messages while the subscriber unit is generating messages at too rapid of a rate. 
     All objects, features, and advantages of the present invention will become apparent in the following detailed written description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 depicts an illustrative embodiment of a wireless communication network with which the method and system of the present invention may advantageously be utilized; 
     FIG. 2 is a high-level logical flowchart of a method of operating a base station controller in accordance with the present invention; 
     FIG. 3 is a high-level block diagram of a subscriber unit in accordance with the present invention; and 
     FIG. 4 is a high-level logical flowchart of a method of operating a subscriber unit in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings and in particular to FIG. 1, there is depicted a high-level diagram of a wireless communication network  10  in which a preferred embodiment of the present invention may advantageously be implemented. Wireless communication network  10  may utilize an analog protocol such as advanced mobile phone service (AMPS), but preferably employs a digital protocol such as code-division multiple access (CDMA). As shown, wireless communication network  10  includes a mobile switching center (MSC)  16  that supports various call, data and messaging functions for a multiple-access technology such as CDMA, as well as connectivity to a public switched telephone network (PSTN)  20 . Coupled to BSC  14  is a base station controller (BSC)  14  that generally comprises signal processing resources  22 , which may be implemented as one or more mid-range computer systems, and a system parameters database  24 . BSC  14  controls the operation of several base transceiver stations (BTSs)  12   a - 12   n  distributed at various locations within communication network  10  in accordance with the system parameters stored in system parameters database  24 . Within the service area of wireless communication network  10 , there are also several mobile stations (also known as mobile subscriber units), such as mobile stations  18   a ,  18   b ,  18   c ,  18   d  and  18   e , which transmit and receive calls, pages, data and control messages over-the-air with base transceiver stations  12   a - 12   n . Although the present invention is described below with reference to mobile stations  18 , those skilled in the art will appreciate from the following description that the present invention is also applicable to wireless local loop (WLL) implementations in which the subscriber units are generally fixed in a residence or business premises. 
     Referring now to FIG. 2, there is depicted a high-level logical flowchart of a method of operating base station controller (BSC)  14  in accordance with the present invention. As illustrated, the process begins at block  30  and thereafter proceeds to block  32 , which depicts base station  14  storing in system parameters database  24  an autonomous messaging parameter that regulates autonomous messaging by mobile stations  18 . The autonomous messaging parameter, which can be selected by the service provider, preferably defines a minimum time interval (referred to as the autonomous messaging interval) between autonomous messages transmitted by any one mobile station  18 . As shown at block  34 , BSC  14  periodically broadcasts the autonomous messaging parameter over-the-air to mobile stations  18  via BTSs  12 . The autonomous messaging parameter is preferably provided in a field of an overhead System Parameters Message, which may be broadcast at a frequency of about once every 1 to 2 seconds (e.g., once every 1.28 seconds in an exemplary embodiment). For example, in a WLL implementation, the autonomous messaging parameter may be specified as the AUTO_WLL_INTERVAL of the Extended System Parameters Message defined by the TIA/EIA/IS-2000.5-A standard for Third Generation (3G) CDMA systems, which is incorporated herein by reference. Following block  34 , the process proceeds to block  36 , where processing by BSC  14  continues. 
     With reference now to FIG. 3, there is illustrated a high-level block diagram of a mobile station  18  or other subscriber unit in accordance with the present invention. Mobile station  18  includes a controller  40  that generally includes a processor  42  and a memory  44 . Processor  42  executes a control program stored within memory  44  to implement the subscriber unit side of the multiple-access protocol employed by wireless communication network  10 . Mobile station  18  further includes a speaker (ear piece)  46  by which controller  40  presents audio outputs to a subscriber and a microphone (mouth piece)  48  that receives audio inputs from the subscriber. Mobile station  18  also has a keypad  50  by which the subscriber can enter callee telephone numbers and other keyed inputs and a display  52  through which controller  40  can visually present alphanumeric and graphical outputs for viewing by the subscriber. Finally, mobile station  18  includes a radio frequency transceiver  54  for sending and receiving wireless signals, including autonomous messages, over-the-air. 
     Referring now to FIG. 4, there is depicted a high-level logical flowchart of a method of operating a subscriber unit, such as a mobile station  18  or a fixed subscriber station, in accordance with the present invention. The process shown in FIG. 4 is preferably implemented as a portion of the control program executed by processor  42  to implement the subscriber side of the multiple-access protocol employed by wireless communication system  10 . 
     As illustrated, the process shown in FIG. 4 begins at block  70  and thereafter proceeds to block  72 , which depicts processor  42  of a mobile station  18  receiving the autonomous messaging parameter over-the-air from one of BTSs  12  and then storing the autonomous messaging parameter into memory  44 . The process then iterates at block  74  until mobile station  18  generates an autonomous message to be sent over-the-air via one of the access channels. As noted above, a mobile station  18  may generate an autonomous message for any number of reasons. For example, a mobile station  18  or a fixed subscriber unit in a WLL may be required by the implemented protocol to notify BSC  14  of changes in its hook status so that BSC  14  can provide dial tone or other services. In the TIA/EIA/IS-2000.5-A standard incorporated by reference above, a subscriber unit is required to provide notification to the BSC of a change in hook status via a Flash With Information Message. Other types of autonomous messages include Short Message Service (SMS) messages, as well as the Origination Messages, Page Response Messages, and Registration Messages mentioned above. 
     Once mobile station  18  generates an autonomous message, processor  42  utilizes RF transceiver  54  to transmit the autonomous message over-the-air to a BTS  12  via an access channel of the reverse channel, as shown at block  75 . Processor  42  then initializes an autonomous message timer  56  (which may be a variable in memory  44  as shown in FIG. 3) to an autonomous messaging interval specified by the autonomous messaging parameter and starts (e.g., begins decrementing) autonomous message timer  56  to track elapsed time, as shown at block  76 . The purpose of autonomous message timer  56  is to prevent the sending of another autonomous message until an autonomous messaging interval specified by the autonomous messaging parameter has elapsed. 
     If mobile station  18  then generates another autonomous message to be sent over-the-air via one of the access channels, the process passes to block  78  via decision block  77 . However, if mobile station  18  has not generated an autonomous message, the process simply iterates at block  77  until mobile station  18  generates another autonomous message. When mobile station  18  generates an autonomous message, processor  42  determines at block  78  whether or not autonomous message timer  56  has a value of zero or less, thereby indicating that the autonomous messaging interval between autonomous messages has elapsed. If so, the process proceeds from block  78  to block  90 , which is described below. However, if processor  42  determines at block  78  that autonomous message timer  56  has a value greater than zero, then the autonomous message cannot be transmitted over-the-air at present without violating the autonomous messaging interval specified by the autonomous messaging parameter. FIG. 4 illustrates two alternative methods by which this operating scenario may be handled. 
     Blocks  80 - 84  depict a preferred embodiment in which transmission of the autonomous message is delayed until an entire autonomous messaging interval has elapsed without mobile station  18  generating another autonomous message. In this preferred embodiment, processor  42  re-initializes autonomous message timer  56  with the autonomous messaging interval at block  80  and then restarts autonomous message timer  56 . As shown at blocks  82  and  84 , if mobile station  18  generates another autonomous message prior to the expiration of autonomous message timer  56 , then the process returns to block  80 . Otherwise, the process passes from block  84  to block  90 . Thus, in this preferred embodiment, which safeguards against excessive autonomous messaging by malfunctioning mobiles, an autonomous message generated by mobile station  18  will not be transmitted over-the-air to BTS  12  until autonomous messaging timer  56  expires (e.g., has a value less than or equal to zero) without mobile station  18  generating another autonomous message. 
     If this level of regulation of autonomous messaging is not desirable, the process shown in FIG. 4 can alternatively handle premature generation of an autonomous message by simply iterating at block  78  (as indicated by dashed line illustration) until autonomous message timer  56  reaches a value of zero and then preceding to block  90 . Thus, in this alternative embodiment, only the transmission of autonomous messages is regulated, rather than both the stability of the subscriber station and the transmission of autonomous messages as in the preferred embodiment. 
     Following either block  78  or block  84 , the process shown in FIG. 4 passes to block  90 , which depicts processor  42  utilizing RF transceiver  54  to transmit the autonomous message detected at block  77  over-the-air to a BTS  12  via an access channel of the reverse channel. The receiving BTS  12  in turn sends the autonomous message to BSC  14  for appropriate handling by signal processing resources  22 . Following transmission of the autonomous message from mobile station  18 , the process shown in FIG. 4 returns to block  76 , which has been described. 
     As has been described, the present invention provides an improved method and system for regulating autonomous messaging by subscriber units in a wireless communication network. In accordance with the present invention, an autonomous messaging parameter that indicates an autonomous messaging interval is broadcast to subscriber units in the wireless communication network. The subscriber units utilize the autonomous messaging parameter to regulate autonomous messaging, for example, by utilizing the autonomous messaging interval to ensure stability of subscriber stations that generate autonomous messages and/or by enforcing the autonomous messaging interval between transmission of autonomous messages. In this manner, judicious use of the limited bandwidth of shared access channels in the reverse channel is ensured. 
     While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. For example, although aspects of the present invention have been described with respect to computer systems, mobiles and other data processing systems executing software, such as SIP clients, servers and proxies, that direct the functions of the present invention, it should be understood that present invention may alternatively be implemented as a program product for use with the above-mentioned and other data processing systems. Programs defining the functions of the present invention can be delivered to a data processing system via a variety of signal-bearing media, which include, without limitation, non-rewritable storage media (e.g., CD-ROM), rewritable storage media (e.g., a floppy diskette or hard disk drive), and communication media, such as digital and analog networks. It should be understood, therefore, that such signal-bearing media, when carrying or encoding program instructions that direct the functions of the present invention, represent alternative embodiments of the present invention.