Abstract:
A mobile station ( 16 ) may include a terminal equipment ( 10 ), a mobile station modem ( 14 ), a mobile telephone ( 12 ), and other features. A CPU ( 52 ) selectively generates control signals to efficiently control transmission of supplemental channel request messages (SCRM) by the mobile station ( 16 ). In one embodiment, transmission of a SCRM in response to a predetermined event is prohibited until a fixed period of time has elapsed since the last transmission of an SCRM in response to the predetermined event.

Description:
RELATED APPLICATIONS  
       [0001]    This applications claims priority to U.S. Provisional Application No. 60/325,702 filed on Sep. 27, 2001 and U.S. Provisional Application No. 60/383,250 filed on May 23, 2002. 
     
    
     
       BACKGROUND  
         [0002]    1. Technical Field  
           [0003]    The technical field generally relates to the field of wireless communications. More particularly, the technical field relates to a system and method for efficient transmission of a supplemental channel request message (SCRM) for a reverse supplemental channel (R-SCH) in a wireless communications device.  
           [0004]    2. Description of the Related Art  
           [0005]    Recent advances in wireless communications and the rapid expansion of use of the Internet have greatly increased the demand for mobile computing. Technologies for allowing a large number of system users to share a communication system, such as Code Division Multiple Access (CDMA) technology, have played a critical role in meeting that demand.  
           [0006]    CDMA is a digital radio-frequency (RF) technique defined in the Telecommunications Industry Association/Electronics Industries Association Interim Standard-95, entitled “MOBILE STATION-BASE STATION COMPATIBILITY STANDARD FOR DUAL-MODE WIDEBAND SPREAD SPECTRUM CELLULAR SYSTEM,” which was published in July 1993 and which is incorporated herein by reference.  
           [0007]    CDMA communication devices are assigned a unique code and each device uses its code to spread its communication signals across a common spread-spectrum bandwidth. As long as the communication device has the correct code, it can successfully detect and select its signal from among other signals concurrently transmitted over the same bandwidth.  
           [0008]    Other multiple access techniques include time division multiple access (TDMA) and frequency division multiple access (FDMA) systems. There are also analog frequency modulation (FM) based wireless communication systems, such as the Advanced Mobile Phone System (AMPS). In addition, many wireless communication devices combine communications capabilities with global position system (GPS) techniques. Some wireless communication systems are capable of operating using multiple techniques, such as CDMA and GPS, or on different frequency bands, such as cellular or Personal Communication Services (PCS) bands.  
           [0009]    The increased reliability of mobile communications has led to a demand for remote wireless computing where a computing device, such as a laptop computer or palmtop computer, is remotely coupled to a computer network (e.g., the Internet) via the mobile telephone.  
           [0010]    [0010]FIG. 1 is a functional block diagram illustrating a wireless data connection. In FIG. 1 a terminal equipment (TE)  10  may be a laptop, palmtop, or other conventional computing device. The TE  10  is coupled to a wireless communication device, such as a mobile telephone (MT)  12 , usually through a mobile system modem (MSM)  14 . The MSM  14  may be incorporated into the TE  10  or into the MT  12 .  
           [0011]    The TE  10 , MT  12  and MSM  14  may conveniently be collectively characterized as a mobile station (MS)  16 , as indicated by the dashed lines in FIG. 1. In fact, the MS  16  may be an integrated device comprising a TE  10 , an MT  12 , and an MSM  14 .  
           [0012]    The wireless communication system of FIG. 1 also includes a base station transceiver system (BTS)  18 . The BTS  18  communicates with the MS  16  via a wireless communication link  20 .  
           [0013]    To establish a communication link between the MS  16  and the BTS  18 , communication signals are exchanged. Various protocols and standards provide a framework for implementing a wireless data connection. The actual implementation of hardware and software within that framework is left to the discretion of the designer.  
           [0014]    Such implementations may take advantage of the fact that in most communication sessions the MS  16  receives much more data from the BTS  18  (forward channel communication) than the MS  16  transmits to the BTS  18  (reverse channel communication). Thus, less bandwidth may normally be assigned for reverse channel communication, with additional bandwidth assigned as the amount of data to be transmitted increases. In one such implementation the BTS  18  is configured to assign a reverse supplemental channel (R-SCH) with an assigned data rate and burst length to an MS  16  in response to a supplemental channel request message (SCRM) from the MS  16 .  
           [0015]    Typically, at call setup the MS  16  and the BTS  18  will negotiate a maximum agreed R-SCH data rate. The negotiated rate may be based on various factors, such as the maximum rate the MS  16  can support and the amount of available power resources of the MS  16  to be allocated to reverse channel communication. The MS  16  sends a non-zero length SCRM to the BTS  18  to indicate a R-SCH is needed in response to certain triggering events.  
           [0016]    For example, the MS  16  may send an SCRM when it does not have an R-SCH assignment and a certain number of bytes are buffered for transmission to the BTS  18 . The MS  16  may also send an SCRM when the assigned R-SCH data rate is too high or too low for the current operating conditions. The MS  16  may also send a zero-length SCRM to cancel a R-SCH.  
           [0017]    The MS  16  may request a R-SCH. In response, the BTS  18  may assign a R-SCH and notify the MS  16  of the assignment with an extended supplemental channel assignment message (ESCAM) or a universal handoff direction message (UHDM). Moreover, the BTS  18  may not grant the requested data rate or may not grant the request at all. In addition, there may be a delay in granting the request. The BTS  18  may also send a retry delay message to the MS  16 .  
           [0018]    To prevent flooding of the BTS  18  with SCRMs, the MS  16  may be configured not to send a request until a delay period has elapsed from the last SCRM, even though a triggering event has occurred. For example, an MS  16  may be configured not to send an SCRM more than once a second. Even with this restriction, however, an MS  16  may transmit too many SCRMs, including SCRMs which are not likely to result in a more optimal assignment of R-SCHs by the BTS  18 . In addition, when the amount of data to be transmitted exceeds the capacity of a currently assigned R-SCH, there can be a significant delay between the termination of the current R-SCH burst and the start of a subsequent R-SCH.  
           [0019]    Therefore, it can be appreciated that there is a significant need for an efficient system and method for controlling transmission of an SCRM for a R-SCH in a wireless communication device.  
         BRIEF SUMMARY  
         [0020]    The system and method described herein are directed to controlling transmission of supplemental channel request messages (SCRM) by a wireless communication device. In one embodiment, the system may be configured to prevent transmission of a SCRM in response to a predetermined triggering event until a fixed period of time has elapsed since the last transmission of a SCRM in response to the predetermined triggering event. In another embodiment, the system may be configured to prohibit transmission of a SCRM when a reverse supplemental channel (R-SCH) burst has been assigned but has not started. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]    [0021]FIG. 1 is a functional block diagram of wireless link of an MS with a BTS.  
         [0022]    [0022]FIG. 2 is a functional block diagram of a MS of an embodiment.  
         [0023]    [0023]FIG. 3 is a timing diagram illustrating the operation of an embodiment.  
         [0024]    [0024]FIG. 4 is a timing diagram illustrating the operation of an embodiment.  
         [0025]    [0025]FIG. 5 is a timing diagram illustrating the operation of an embodiment.  
         [0026]    [0026]FIG. 6 is a timing diagram illustrating the operation of an embodiment.  
         [0027]    [0027]FIG. 7 is a timing diagram illustrating the operation of an embodiment.  
         [0028]    [0028]FIG. 8 is a flow chart illustrating the operation of an embodiment.  
         [0029]    [0029]FIG. 9 is a flow chart illustrating the operation of an embodiment.  
         [0030]    [0030]FIG. 10 is a flow chart illustrating the operation of an embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0031]    The system and method described herein is directed to efficient transmission of SCRMs in a mobile communications device.  
         [0032]    As noted above, a number of different standards exist to govern wireless data communication. These standards may be implemented in a number of different ways to provide some flexibility to the designer. FIG. 1 illustrates the simplified general wireless connection that supports the communication process.  
         [0033]    A system is embodied in an MS  16  illustrated in the functional block of FIG. 2. The MS  16  includes a central processing unit (CPU)  22  and a memory  24 , which controls operation of the system. Those skilled in the art will appreciate that the term “CPU” is intended to encompass any processing device, alone or in combination with other devices such as a memory (not shown), that is capable of operating the MS  16  or a portion thereof. This includes microprocessors, embedded controllers, application specific integrated circuits (ASICs), digital signal processors (DSPs), state machines, dedicated discrete hardware, and the like. The system and method described herein are not limited by the specific hardware component selected to implement the CPU  22 . Moreover, after reviewing the specification one of skill in the art will recognize that the CPU  22  may be incorporated into other components of the MS  16 , including the MSM  14 , the MT  12  or the TE  10 .  
         [0034]    The memory  24 , which may include both read-only memory (ROM) and random-access memories (RAM), provides instructions and data to the CPU  22 . A portion of the memory  24  may also include non-volatile random-access memory.  
         [0035]    The MS  16  also includes a transmitter  30  and a receiver  32  to allow transmission and reception of data, such as audio communication and programming data, between the MS  16  and a remote location, such as a base transceiver station (BTS)  18  (see FIG. 1). As mentioned above, the transmitter  30  and the receiver  32  may be combined into a transceiver  34 . An antenna  36  is electrically coupled to the transceiver  34 . The operation of the transmitter  30 , receiver  32 , and antenna  36  is well-known in the art and need not be described herein.  
         [0036]    The MS  16  also includes an SCRM controller  54 , which may typically be implemented by the CPU  22 , executing instructions stored in the memory  24 . The MS  16  may use the SCRM controller  54  to generate control signals to control the transmission of SCRMs by the MS  16 .  
         [0037]    The MS  16  also includes an SCRM timer  56 , and an event timer  58 , both of which may typically be implemented by the CPU  52  or the SCRM controller  54 . As will be described in detail below, the SCRM controller  54  uses the timers  56 ,  58  to control SCRM transmissions.  
         [0038]    The various components of the MS  16  are coupled together by a bus system  60  which may include a power bus, control bus and status signal bus in addition to a data bus. For the sake of clarity, however, the various buses are illustrated in FIG. 2 as the bus system  60 .  
         [0039]    Those of skill in the art will recognize that the MS  16  may contain other components, such as a battery (not shown), and input/output devices (not shown), and that the components can be arranged in various configurations. For example, FIG. 2 illustrates the TE  10  coupled to the MT  12  via the MSM  14 , as also illustrated in FIG. 1. However, the TE  10  may be coupled directly to the bus system  60  if the TE  10 , MT  12  and MSM  14  are integrated into the MS  16 . The system and method described herein are not limited to the specific configuration and arrangement of components shown.  
         [0040]    The SCRM controller  54  may use the timers  56 ,  58  to determine when to generate control signals to control the transmission of SCRMs by the MS  16 . The SCRM timer  56  may be started or restarted when the MS  16  transmits an SCRM for a non-zero R-SCH. The SCRM timer  56  may be cancelled when a fixed time period has elapsed or when the MS  16  receives either an ESCAM or a UHDM with a non-zero R-SCH assignment. The SCRM controller  54  may be configured to disable the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH when the SCRM timer  56  is running. After reviewing this specification, one of skill in the art will recognize that the time period may be fixed at the factory, may be fixed by the user, may be fixed by the SCRM controller  54  in response to RF conditions, or the amount of traffic on the channel, or may be fixed in response to a signal received by the MS  16 .  
         [0041]    The event timer  58  may be started or restarted whenever a predetermined event occurs. For example, the predetermined event may be transmission of an SCRM by the MS  16  in response to a particular triggering event. The predetermined event may also be the start of an assigned R-SCH burst. The event timer  58  may also be started or restarted when one of a plurality of predetermined events occurs.  
         [0042]    The event timer  58  may be cancelled when a fixed time period has elapsed, when a current R-SCH burst ends, or when an ESCAM to cancel an R-SCH is received and there is no current R-SCH burst active. After reviewing this specification, one of skill in the art will recognize that the time period may be fixed at the factory, may be fixed by the user, may be fixed by the SCRM controller  54  in response to RF conditions or traffic on the channel, or may be fixed in response to a signal received by the MS  16 . The fixed time period when the event timer  58  expires need not be the same fixed time period when the SCRM timer  56  expires.  
         [0043]    The SCRM controller  54  may be configured to disable the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH in response to a predetermined triggering event when the event timer  58  is running. The SCRM controller  54  may also be configured to disable the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH in response to any one of a plurality of predetermined triggering events when the event timer  58  is running.  
         [0044]    In an exemplary embodiment, the SCRM controller  54  may be configured to generate control signals to cause the transmission of a burst extension SCRM for a non-zero R-SCH when the MS  16  determines the current R-SCH burst is not adequate for current data needs, and before the current R-SCH burst ends. For example, the MS  16  may determine that the number of bytes or frames remaining to be transmitted exceeds the number of bytes or frames that can be transmitted in the current R-SCH burst. In response to a burst extension SCRM, the BTS  18  may assign a new R-SCH burst, or may deny the request. Use of burst extension SCRMs helps to reduce the time between expiration of the current R-SCH burst and the start of the next R-SCH burst. In an exemplary embodiment, the newly assigned R-SCH burst will either overlap or be contiguous with the current R-SCH burst. In an exemplary embodiment, the transmission of a burst extension SCRM will not be one of the predetermined events that results in the starting or restarting of the event timer  58 .  
         [0045]    The SCRM controller  54  may disable the ability of the MS  16  to transmit a burst extension SCRM when the SCRM timer  56  is running. The ability of the MS  16  to transmit a burst extension SCRM may also be further restricted. For example, it may be prohibited until the burst length remaining in the current R-SCH is below a predetermined threshold value, such as a certain number of remaining available frames or until a fixed time period before the end of the current R-SCH burst. The predetermined threshold value may be set at the factory, set by the user, set in response to RF conditions or traffic on the channel, or set in response to a signal received by the MS  16 . The period in which a burst extension SCRM may be transmitted to request extension of a current R-SCH burst, assuming other conditions permit transmission of a burst extension SCRM, may be referred to as the burst extension gap. Additional timers may be employed to implement additional restrictions on the ability of the MS  16  to transmit a burst extension SCRM.  
         [0046]    In another exemplary embodiment, the SCRM controller  54  may be configured to disable the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH (whether to request a burst extension or in response to another triggering event) during the time period after an ESCAM or UHDM assigning a non-zero R-SCH is received and before the assigned R-SCH burst starts or another message canceling the assigned non-zero R-SCH is received.  
         [0047]    The SCRM controller  54  may be readily implemented as a series of instructions stored in the memory  24  and executed by the CPU  22 . Thus, minor software modifications to existing hardware will allow the implementation of the MS  16 .  
         [0048]    For purposes of brevity, the operation of the MS  16  to efficiently transmit SCRMs will be illustrated using a limited number of examples. To simplify the illustrations, events are generally shown as occurring at evenly-spaced time intervals. However, events may occur at different time intervals and in different orders than as illustrated.  
         [0049]    [0049]FIG. 3 is a timing diagram illustrating the operation of an embodiment of the MS  16 . In the embodiment illustrated in FIG. 3, the MS  16  is configured to start or restart the event timer  58  in response to the following predetermined events: the MS  16  transmits a non-zero R-SCH SCRM because there is no current R-SCH burst and the amount of data to be transmitted to the BTS  18  exceeds a threshold value; the MS  16  transmits a non-zero R-SCH SCRM because the data rate of the current R-SCH burst is not optimal; and an R-SCH burst starts. The SCRM controller  54  is configured to disable the ability of the MS  16  to transmit a non-zero R-SCH SCRM in response to the following triggering events when the event timer  58  is running: there is no current R-SCH burst and the amount of data to be transmitted to the BTS  18  exceeds a threshold value; and the data rate of the current R-SCH burst is not optimal.  
         [0050]    At time  300 , no R-SCH is active and the MS  16  sends a non-zero R-SCH SCRM because the amount of data to be transmitted to the BTS  18  exceeds a threshold value. The SCRM timer  56  is started because a non-zero R-SCH SCRM was transmitted. The event timer  58  is started because one of the predetermined events has occurred—a non-zero R-SCH SCRM was transmitted when no current R-SCH burst was active because the amount of data to be transmitted to the BTS  18  exceeded a threshold value. Between time  300  and  310 , the SCRM controller  54  disables the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH because the SCRM timer  56  is running. During this time period, the SCRM controller  54  also disables the ability of the MS  16  to transmit an R-SCH SCRM in response to one of the predetermined triggering events because the event timer  58  is running.  
         [0051]    At time  310  the MS  16  receives an ESCAM assigning a non-zero R-SCH burst. In response to receipt of the ESCAM, the SCRM timer  56  is stopped. The event timer  58  continues to run. Between time  310  and  320 , the SCRM controller  54  disables the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH in response to one of the predetermined triggering events because the event timer  58  is running. In the exemplary embodiment illustrated in FIG. 3, the SCRM controller  54  disables the ability of the MS  16  to transmit any SCRM for a non-zero R-SCH because an ESCAM has been received assigning a non-zero R-SCH burst and the assigned burst has not yet started. This is illustrated in FIG. 3 as the ESCAM Transmission/SCRM disable.  
         [0052]    At time  320 , the fixed time period for the event timer  58  to operate expires. The event timer  58  stops. In the exemplary embodiment illustrated in FIG. 3, between time  320  and  330  the SCRM controller  54  disables the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH because a non-zero R-SCH burst has been assigned but has not yet started. As noted above, this is illustrated in FIG. 3 as the ESCAM Transmission/SCRM disable.  
         [0053]    At time  330 , the assigned R-SCH burst starts. The event timer  58  is started to prevent the MS  16  from instantly transmitting an SCRM because the MS  16  is not satisfied with the assigned data rate. The SCRM timer  56  remains stopped. Between time  330  and  340 , the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH in response to one of the predetermined triggering events is disabled because the event timer  58  is running. The ability of the MS  16  to transmit a burst extension SCRM for a non-zero R-SCH is enabled because the SCRM timer  56  is not running and the current R-SCH burst has started. In another embodiment, the ability of the MS  16  to transmit a burst extension SCRM for a non-zero R-SCH may continue to be disabled because other criteria for enablement may not be satisfied. For example, the number of available frames in the current R-SCH burst may exceed a threshold level. In other words, the current R-SCH burst may not be in the burst extension gap.  
         [0054]    At time  340 , the MS  16  determines that the current R-SCH burst is insufficient to meet the data transmission needs of the MS  16 . The SCRM controller  54  generates control signals to cause the MS  16  to transmit a burst extension SCRM for a non-zero R-SCH. In response to the burst extension SCRM, the SCRM timer  56  is started. Between time  340  and  350  the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH is disabled because the SCRM timer  56  is running. The event timer  58  is not restarted, since the SCRM was for a burst extension, and was not due to a triggering event.  
         [0055]    At time  350 , the current R-SCH burst ends. In response to the end of the current R-SCH burst, the event timer  58  is turned off. As illustrated, the event timer  58  would also be turned off because the fixed time period for the event timer  58  to operate expired. After reviewing the specification, one of skill in the art will recognize that the end of the current R-SCH burst will not necessarily coincide with the expiration of the fixed period of time for the event timer  58  to operate. Between time  340  and  350 , the ability of the MS  16  to transmit an SCRM for a non-zero R-SCH for any reason is disabled because the SCRM timer  56  is running.  
         [0056]    [0056]FIG. 4 is a timing diagram illustrating the operation of an embodiment when no response is received to a non-zero R-SCH SCRM transmitted in response to one of the predetermined triggering events. At time  410 , the MS  16  transmits an SCRM for a non-zero length R-SCH in response to one of the predetermined triggering events. Both timers  56 ,  58  are started. Between time  410  and  420 , the MS  16  cannot transmit an SCRM for a non-zero R-SCH because the SCRM timer  56  is running.  
         [0057]    At time  420 , the SCRM timer  56  expires. At time  430  the event timer  58  expires. Between time  420  and  430  the MS  16  cannot transmit an SCRM for a non-zero length R-SCH in response to one of the predetermined triggering events because the event timer  58  is running. The MS  16  cannot transmit a burst extension SCRM because there is no current R-SCH burst active. After time  430  the MS  16  can transmit an SCRM for a non-zero R-SCH in response to one of the predetermined events because both timers  56 ,  58  have expired and no message, such as an ESCAM or UHDM, assigning a non-zero R-SCH burst has been received. The MS  16  cannot transmit a burst extension SCRM because there is no current R-SCH burst active. Thus, FIG. 4 does not show any time period during which the MS  16  can transmit a burst extension SCRM.  
         [0058]    [0058]FIG. 5 is a timing diagram illustrating the operation of an embodiment when a response to a burst extension SCRM is not received. At time  510  the SCRM timer  56  is off, the event timer  58  is running and a current R-SCH burst is active. Between time  510  and  520 , the MS  16  cannot transmit a non-zero SCRM in response to one of the predetermined triggering events because the event timer  58  is running. The MS  16  cannot transmit a burst extension SCRM because the current burst is longer than the burst extension gap, because, for example, the number of frames remaining in the current R-SCH may be above a threshold value.  
         [0059]    At  520  the number of available frames in the current R-SCH burst drops below a threshold value and, because the SCRM timer  56  is not running, the ability of the MS  16  to transmit a burst extension SCRM is enabled. The time between time  520  and the end of the current burst at time  540  is the burst extension gap.  
         [0060]    At time  530 , the MS  16  determines that the current burst length is insufficient and transmits a burst extension SCRM. In response to the burst extension SCRM, the SCRM timer  56  is started. The event timer  58  is not reset because the SCRM was not due to one of the predetermined triggering events. Between time  530  and  540  the MS  16  cannot transmit a non-zero R-SCH SCRM, whether due to one of the predetermined triggering events or to request a burst extension R-SCH, because the SCRM timer  56  is running.  
         [0061]    At time  540 , the current R-SCH burst ends and, in response, the event timer  58  is stopped. Between time  540  and  550 , the MS  16  cannot transmit a non-zero R-SCH SCRM, whether due to a predetermined triggering event or to request a burst extension R-SCH, because the SCRM timer  56  is running. The ability of the MS  16  to transmit a burst extension SCRM is disabled for the additional reason that there is no burst extension gap because there is no current R-SCH burst.  
         [0062]    At time  550  the SCRM timer  56  expires and the ability of the system to transmit a non-zero R-SCH SCRM in response to one of the predetermined triggering events is enabled because both timers  56 ,  58  are stopped and no message assigning a non-zero R-SCH burst has been received. At time  560 , the MS  16  transmits an SCRM for a non-zero R-SCH in response to a predetermined triggering event. In response, both timers  56 ,  58  are started.  
         [0063]    [0063]FIG. 6 is a timing diagram illustrating the operation of an embodiment when the burst length of an assigned R-SCH is less than the burst extension gap. At time  610  the MS  16  transmits a non-zero R-SCH SCRM in response to one of the predetermined triggering events. In response, both timers  56 ,  58  are started. Between time  610  and  620  the MS  16  cannot transmit a non-zero R-SCH SCRM.  
         [0064]    At time  620  an ESCAM is received assigning a non-zero R-SCH and the SCRM timer  56  is stopped. The burst length of the assigned R-SCH, however, is less than the burst extension gap. The MS  16  cannot transmit a non-zero R-SCH SCRM because a R-SCH burst has been assigned, but has not yet started. The MS  16  cannot transmit a non-zero R-SCH SCRM in response to one of the predetermined triggering events for the additional reason that the event timer  58  is running.  
         [0065]    At time  630  the assigned R-SCH burst starts. In response, the event timer  58  is restarted. Assuming the amount of data to be transmitted is sufficient to warrant a burst extension SCRM, the MS  16  will almost instantly transmit a burst extension SCRM because the burst length is less than the burst extension gap and the SCRM timer  56  is not running. This is illustrated in FIG. 6 as occurring at time  631 . Transmission of the burst extension SCRM will cause the SCRM timer  56  to start. At time  640  the current burst termiinates, which results in the stopping of the event timer  58 .  
         [0066]    [0066]FIG. 7 is a timing diagram illustrating the operation of an embodiment when a scheduled R-SCH burst is cancelled. At time  710  a non-zero R-SCH SCRM is transmitted in response to a predetermined triggering event. Both timers  56 ,  58  are started. At time  720  an ESCAM is received assigning a non-zero R-SCH. In response, the SCRM timer  56  is stopped. The MS  16  cannot transmit a non-zero R-SCH SCRM because a non-zero R-SCH burst has been assigned but has not started. This is illustrated in FIG. 7 as the ESCAM Transmission/SCRM disable. Also, the event timer  58  is running so a non-zero R-SCH SCRM due to one of the predetermined triggering events is not permitted.  
         [0067]    At time  730  an ESCAM is received which cancels the scheduled R-SCH burst. In response, the event timer  58  is stopped and the MS  16  is permitted to transmit a non-zero SCRM in response to a predetermined triggering event.  
         [0068]    [0068]FIG. 8 is a flow chart illustrating the operation of an embodiment when a predetermined triggering event occurs. At step  800  the MS  16  is started. At step  810  the MS  16  determines whether a non-zero R-SCH SCRM is desired due to a predetermined triggering event. If the answer is YES, the MS  16  proceeds to step  820 . If the answer is NO, the MS  16  returns to step  810 .  
         [0069]    At step  820  the MS  16  determines whether the SCRM timer  56  is running. If the answer is YES, the MS  16  returns to step  810  because a non-zero R-SCH SCRM may not be transmitted while the SCRM timer  56  is running. If the answer is NO, the MS  16  proceeds to step  830 .  
         [0070]    At step  830  the MS  16  determines whether the event timer is running. If the answer is YES, the MS  16  returns to step  810  because a non-zero R-SCH SCRM in response to a predetermined triggering event may not be transmitted while the event timer  58  is running. If the answer is NO, the MS  16  proceeds to step  840 .  
         [0071]    At step  840  the MS  16  determines whether a message that a non-zero R-SCH burst is scheduled for the future has been received. If the answer is YES, the MS  16  returns to step  810  because a non-zero R-SCH SCRM may not be transmitted if a non-zero R-SCH burst is scheduled but has not yet started. If the answer is NO, the MS  16  proceeds to step  850 .  
         [0072]    At step  850 , the MS  16  transmits a SCRM requesting a non-zero R-SCH in response to the predetermined triggering event and proceeds to step  860 . At step  860 , the MS  16  resets the SCRM and event timers  56  and  58  and proceeds to step  870  where processing of the predetermined triggering event by the MS  16  terminates. After reviewing the specification, one of skill in the art will recognize that the steps illustrated in FIG. 8 need not occur in the particular order illustrated and that steps may be omitted and additional steps may be performed in different embodiments.  
         [0073]    [0073]FIG. 9 is a flow chart illustrating the operation of an embodiment when the MS  16  determines that the current R-SCH burst is insufficient to transmit the current data needs of the MS  16 . At step  900  the MS  16  is started. At step  910  the MS  16  determines whether a burst extension is desired. In an exemplary embodiment, the answer to this question will always be NO if there is no current burst. If the answer at step  910  is NO, the MS  16  returns to step  910 . If the answer at step  910  is YES, the MS  16  proceeds to step  920 .  
         [0074]    At step  920 , the MS  16  determines whether the current burst is in the burst extension gap. If the answer at step  920  is NO, the MS  16  returns to step  910 . If the answer at step  920  is YES, the MS  16  proceeds to step  930 .  
         [0075]    At step  930 , the MS  16  determines whether the SCRM timer  56  is running. If the answer at step  930  is YES, the MS  16  returns to step  910 . If the answer at step  930  is NO, the MS  16  proceeds to step  940 .  
         [0076]    At step  940  the MS  16  transmits a non-zero burst extension SCRM and proceeds to step  950 . At step  950  the MS  16  starts or restarts the SCRM timer  56  and proceeds to step  960 , where processing of the burst extension request by the MS  16  terminates.  
         [0077]    After reviewing the specification, one of skill in the art will recognize that the steps illustrated in FIG. 9 need not occur in the particular order illustrated and that steps may be omitted and additional steps may be performed in different embodiments.  
         [0078]    [0078]FIG. 10 is a flow chart illustrating the operation of another embodiment when the MS  16  determines that a current R-SCH burst is not optimal. At step  1000 , the MS  16  is started. At step  1010  the MS  16  determines whether a burst extension is desired. In an exemplary embodiment, the answer to this question will always be NO if there is no current R-SCH burst. If the answer at step  1010  is NO, the MS  16  proceeds to step  1020 . If the answer at step  1010  is YES, the MS  16  proceeds to step  1030 .  
         [0079]    At step  1020 , the MS  16  determines whether a different R-SCH burst is desired. If the answer at step  1020  is NO, the MS  16  returns to step  1010 . If the answer at step  1020  is YES, the MS  16  proceeds to step  1070 .  
         [0080]    At step  1030 , the MS  16  determines whether a current burst is in the burst extension gap. If the answer at step  1030  is YES, the MS  16  proceeds to step  1040 . If the answer at step  1030  is NO, the MS  16  proceeds to step  1020 .  
         [0081]    At step  1040 , the MS  16  determines whether the SCRM timer  56  is running. If the answer at step  1040  is YES, the MS  16  returns to step  1010 . If the answer at step  1040  is NO, the MS  16  proceeds to step  1050 .  
         [0082]    At step  1050 , the MS  16  transmits a non-zero burst extension SCRM and proceeds to step  1060 . At step  1060 , the MS  16  starts or restarts the SCRM timer  56  and proceeds to step  2010 , where processing terminates.  
         [0083]    At step  1070 , the MS  16  determines whether the event timer  58  is running. If the answer at step  1070  is YES, the MS  16  returns to step  1010 . If the answer at step  1070  is NO, the MS  16  proceeds to step  1080 .  
         [0084]    At step  1080 , the MS  16  determines whether the SCRM timer  56  is running. If the answer at step  1080  is YES, the MS  16  returns to step  1010 . If the answer at step  1080  is NO, the MS  16  proceeds to step  1090 .  
         [0085]    At step  1090 , the MS  16  transmits a non-zero R-SCH SCRM and proceeds to step  2000 . At step  2000 , the MS  16  starts or restarts the event timer  58  and proceeds to step  1060 . As noted above, at step  1060 , the MS  16  starts or restarts the SCRM timer  56  and proceeds to step  2010 , where processing terminates.  
         [0086]    After reviewing the specification, one of skill in the art will recognize that the steps illustrated in FIG. 10 need not occur in the particular order illustrated and that steps may be omitted and additional steps may be performed in different embodiments.  
         [0087]    It is to be understood that even though various embodiments and advantages have been set forth in the foregoing description, the above disclosure is illustrative only, and changes may be made in detail, yet remain within the broad principles of the disclosure. Therefore, the present invention is to be limited only by the appended claims.