Abstract:
A method for setting default values of timers in a wireless communications system includes setting default values of timers Timer_RST and Timer_Poll to be a first value. The timers Timer_RST and Timer_Poll are used to respectively hold retransmission of a reset signaling packet and a polling until an expected response is received.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application No. 60/746,650, filed on May 7, 2006 and entitled “Method and Apparatus of Default Radio Configurations,” the contents of which are incorporated herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a method and related apparatus of default timer configurations of wireless communications system, and more particularly to a method and related apparatus for decreasing delay of a reset procedure. 
   2. Description of the Prior Art 
   The third generation (3G) mobile communications system has adopted a Wideband Code Division Multiple Access (WCDMA) wireless air interface access method for a cellular network. WCDMA can provide high frequency spectrum utilization, universal coverage, and high quality, high speed multimedia data transmission. The WCDMA method also meets all kinds of QoS requirements simultaneously, providing diverse flexible two-way transmission services and better communication quality to reduce transmission interruption rates. Taking Universal Mobile Telecommunications System (UMTS) as an example, the 3G mobile communications system is composed of User Equipment (UE), UMTS Terrestrial Radio Access Network (UTRAN), and Core Network (CN), using communications protocols of Access Stratum (AS) and Non-Access Stratum (NAS). Targeting the AS, the 3G mobile communications system defines various protocol stacks, such as Radio Resource Control (RRC), Radio Link Control (RLC), Media Access Control (MAC), Packet Data Convergence Protocol (PDCP), and Broadcast/Multicast Control (BMC). 
   To implement functions of the aforementioned protocol stacks, the 3rd Generation Partnership Project (3GPP) has established related communication protocol specifications as its website, www.3gpp.org, presents. The communication protocol specifications provide default configurations for variables and parameters, so as to enhance system efficiency, and to reduce the signaling messages during radio connection setup for a UE. However, some default configurations may affect system operations, causing waste of radio resources. For example, in a communications protocol specification established by the 3GPP(3GPPTS 25.331 V6.9.0 (2006-03), “Radio Resource Control (RRC) protocol specification”), the default value of a timer Timer_RST in the uplink configuration is set to be 300 ms (millisecond), a timer Timer_Poll in the uplink configuration is not configured by default, and the default value of a timer Timer_Status_Prohibit in the downlink configuration is set to be 100 ms. However, in another communications protocol specification established by the 3GPP (3GPP TS 34.108 V6.2.0 (2006-03), “Common test environments for User Equipment (UE); Conformance testing”), the default values of the timers Timer_RST and Timer_Poll in the uplink configuration are set to be 500 ms and 200 ms respectively, and the default value of the timer Timer_Status_Prohibit in the downlink configuration is set to be 200 ms. 
   The timers Timer_RST, Timer_Status 13  Prohibit, and Timer_Poll are all used for RLC entities (of UE or/and UTRAN) to hold retransmission of a control signaling (RESET PDU, STATUS report, or polling) until the expected response from the peer RLC entity is received. Note that, descriptions of the three timers can be found in the RLC communications protocol specification established by the 3GPP, and will not be narrated in detail. Thus, all the three timers should be equal to or longer than the round trip time (RTT), which is the time duration between the instant when the signaling is sent out and the instant when the response message is received. To cover variance of processing powers among different UE implementations, the timers are generally configured to be larger than RTT. 
   In the specifications 3GPPTS 25.331 V6.9.0 and 3GPPTS 34.108 V6.2.0, the default values of the timers are different, and the default value of the same timer is inconsistent, causing system efficiency degradation. 
   For example, in 3GPP TS 25.331 V6.9.0, the timer Timer_Status_Prohibit is set to be 100 ms, meaning that RTT is shorter than 100 ms, but the timer Timer_RST is set to be 300 ms. Thus, a RESET PDU will be held for 300 ms before it can be retransmitted if a RESET ACK PDU corresponding to the RESET PDU is not received by the sender. However, since RTT is shorter than 100 ms, if the RESET ACK PDU is not received within 100 ms, the RESET ACK PDU will never arrive later. Thus, retransmission of the RESET PDU is delayed 200 ms (300−100=200) longer than needed. The reset procedure is delayed. 
   Similarly, in 3GPP TS 34.108 V6.2.0, the timers Timer_Status_Prohibit, and Timer_Poll are all set to be 200 ms, meaning that RTT is less than 200 ms. However, the timer Timer_RST is set to be 500 ms. Thus, retransmission of the RESET PDU is delayed 300 ms (500−200=300) longer than needed. The reset procedure is also delayed. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a method for setting default values of timers in a wireless communications system comprises setting default values of timers Timer_RST and Timer_Poll to be a first value, wherein timers Timer_RST and Timer_Poll are used to respectively hold retransmission of a reset signaling packet and a polling until an expected response is received. 
   According to the present invention, a communications device utilized in a wireless communications system for accurately setting default values of timers comprises a control circuit for realizing functions of the communications device, a processor installed in the control circuit for executing a program code to operate the control circuit, and a memory coupled to the processor for storing the program code. The program code comprises setting default values of timers Timer_RST and Timer_Poll to be a first value, wherein timers Timer-RST and Timer_Poll are used to respectively hold retransmission of a reset signaling packet and a polling until an expected response is received. 
   These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a function block diagram of a wireless communications device. 
       FIG. 2  is a diagram of program code of  FIG. 1 . 
       FIG. 3  is a flowchart of a process according to the embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Please refer to  FIG. 1 , which is a functional block diagram of a communications device  100 . For the sake of brevity,  FIG. 1  only shows an input device  102 , an output device  104 , a control circuit  106 , a central processing unit (CPU)  108 , a memory  110 , a program code  112 , and a transceiver  114  of the communications device  100 . In the communications device  100 , the control circuit  106  executes the program code  112  in the memory  110  through the CPU  108 , thereby controlling an operation of the communications device  100 . The communications device  100  can receive signals input by a user through the input device  102 , such as a keyboard, and can output images and sounds through the output device  104 , such as a monitor or speakers. The transceiver  114  is used to receive and transmit wireless signals, delivering received signals to the control circuit  106 , and outputting signals generated by the control circuit  106  wirelessly. From a perspective of a communications protocol framework, the transceiver  114  can be seen as a portion of Layer  1 , and the control circuit  106  can be utilized to realize functions of Layer  2  and Layer  3 . 
   Please continue to refer to  FIG. 2 .  FIG. 2  is a diagram of the program code  112  shown in  FIG. 1 . The program code  112  comprises an application layer  200 , a Layer  3  interface  202 , and a Layer  2  interface  206 , and is coupled to a Layer  1  interface  218 . When a signal is transmitted, the Layer  2  interface  206  forms a plurality of SDUs  208  according to data submitted by the Layer  3  interface  202 , and stores the plurality of SDUs  208  in a buffer  212 . Then, based on the SDUs  208  stored in the buffer  212 , the Layer  2  interface  206  generates a plurality of PDUs  214 , and sends the plurality of PDUs  214  to a destination terminal through the Layer  1  interface  218 . In contrast, when a wireless signal is received, the signal is received through the Layer  1  interface  21   8 , then delivered as PDUs  214  to the Layer  2  interface  206 . The Layer  2  interface  206  restores the PDUs  214  to SDUs  208  and stores the SDUs  208  in the buffer  212 . Last, the Layer  2  interface  206  delivers the SDUs  208  stored in the buffer  212  to the Layer  3  interface  202 . 
   Preferably, operations of the communications device  100  conform to the communications protocol established by the 3GPP. Directed at default configurations of timers, the embodiment of the present invention can set default values of timers Timer_Poll and Timer_RST based on a default timer configuring program code  220 , so as to timely trigger a reset procedure, to enhance transmission efficiency, and to utilize system resources efficiently. 
   Please refer to  FIG. 3 , which illustrates a flowchart diagram of a process  30  according to the embodiment of the present invention. The process  30  is utilized for setting default values of timers in a wireless communications system, and can be complied into the default timer configuring program code  220 . The process  30  comprises steps of:
         Step  300 : Start.   Step  302 : Set default values of timers Timer_RST and Timer_Poll to be a first value.   Step  306 : End.       

   According to the process  30 , the embodiment of the present invention sets the default values of the timers Timer_RST and Timer_Poll to be the first value. Preferably, the first value is equal to or greater than RTT. Furthermore, it is preferred that besides default values, configured values of the timers Timer_RST and Timer_Poll are set to be a second value. Preferably, the second value is equal to the first value. 
   For example, suppose that the first value is set to be a little larger than RTT (e.g. 200 ms or 100 ms). According to the definition of the timer Timer_RST, retransmission of a RESET PDU is triggered by a sender if a RESET ACK PDU corresponding to the RESET PDU is not received by the sender before the timer Timer_RST expires. Since the default value of the timer Timer_RST is a little greater than RTT, the sender can timely retransmit the RESET PDU to trigger the reset procedure. Similar situation happens for polling. 
   Therefore, using the process  30 , the sender can timely retransmit the RESET PDU and poll. 
   Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.