Abstract:
A method of triggering transmission of Scheduling Information (SI) used in a user end (UE) of a wireless communications system includes executing a hybrid automatic repeat request (HARQ) process to transmit a packet containing scheduling information, and triggering transmission of a new SI when the number of transmissions of the packet containing SI is greater than or equal to a predetermined maximum number of transmissions, and the UE has not received an acknowledgement message corresponding to the packet containing SI.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/767,182, filed on Mar. 8, 2006 and entitled “Method and Apparatus for Triggering of Scheduling Information Retransmission”, the contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to scheduling information (SI) transmission in wireless communications systems, and more particularly to a method and related apparatus for triggering a new SI transmission that prevents unnecessary SI transmission to increase radio resource usage efficiency. 
         [0004]    2. Description of the Prior Art 
         [0005]    The third generation (3G) mobile telecommunications system has adopted a Wideband Code Division Multiple Access (WCDMA) wireless air interface access method for a cellular network. WCDMA provides 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. Through the 3G mobile telecommunications system, a user can utilize a wireless communications device, such as a mobile phone, to realize real-time video communications, conference calls, real-time games, online music broadcasts, and email sending/receiving. However, these functions rely on fast, instantaneous transmission. Thus, targeting third generation mobile telecommunication technology, the prior art provides High Speed Downlink Package Access (HSDPA) and High Speed Uplink Package Access (HSUPA), which are used to increase bandwidth utility rate and package data processing efficiency to improve uplink/downlink transmission rate. 
         [0006]    HSUPA increases upstream network performance, reduces transmission delay by rapid retransmission of erroneous data transmissions, and can adjust transmission rate based on channel quality. To realize this type of “power control,” HSUPA adopts technologies such as NodeB Scheduling, Hybrid Automatic Repeat Request (HARQ), Soft Handover, and Short Frame Transmission. Correspondingly, the 3rd Generation Partnership Project (3GPP) defines an Enhanced Dedicated Transport Channel (E-DCH) for controlling operations of HSUPA. E-DCH introduces new physical layer channels, such as E-HICH, E-RGCH, E-AGCH, E-DPCCH, and E-DPDCH, which are used for transmitting HARQ ACK/NACK, Uplink Scheduling Information, Control Plane information, and User Plane information. Detailed definitions of the above can be found in the Medium Access Control (MAC) protocol specification, “3GPP TS 25.321 V6.7.0,” and are not given here. The MAC protocol specification defines in detail a method of operating E-DCH MAC-e/es, in which Change Request RP-060194 (http://www.3gpp.org/ftp/tsg_ran/tsg_ran/TSGR — 31/Docs/RP-060194.zip) provides another realization for avoiding Scheduling Information (SI) loss, which targets automatic activation of SI retransmission in the user end (UE) HARQ Process (Section 11.8.1.1.2). 
         [0007]    According to Change Request RP-060194, when generating a transmission, the UE HARQ Process will increment a status variable CURRENT_TX_NB by 1. The status variable CURRENT_TX_NB is used for indicating a number of times an E-DCH MAC-e PDU in an HARQ Buffer has been transmitted. When the status variable CURRENT_TX_NB is greater than a maximum number of transmissions indicated in an HARQ Profile, if the transmission containing SI is triggered, but the UE has not yet received an ACK/NACK from a Radio Link Set (RLS) containing a Serving Cell, the HARQ Process of the UE should notify a Scheduling Information Reporting Function that the HARQ Process failed to deliver the triggered SI to the RLS containing the Serving Cell so as to trigger a new SI transmission. 
         [0008]    Thus, when a packet containing SI has already been transmitted the maximum number of transmissions, after the last transmission, the receiving end may or may not decode the packet, and according to Change Request RP-060194, the HARQ Process will notify the Scheduling Information Reporting Function that the HARQ Process failed to deliver the triggered SI to the RLS containing the Serving Cell, so as to trigger a new SI transmission. In other words, regardless of whether or not the UE receives the ACK/NACK corresponding to the last transmission of the packet, as long as the packet containing SI has been transmitted more than or equal to the maximum number of transmissions, the new SI transmission will be triggered. In this situation, because of a time delay that occurs between transmission of the packet and reception of the ACK/NACK, unnecessary transmission of the SI may occur, which wastes radio resources. 
       SUMMARY OF THE INVENTION 
       [0009]    According to the present invention, a method of triggering transmission of a new Scheduling Information (SI) used in a user end (UE) of a wireless communications system comprises executing a hybrid automatic repeat request (HARQ) process to transmit a packet comprising SI, and triggering transmission of a new SI when a number of transmissions of the packet comprising SI is greater than or equal to a maximum number of transmissions, and the UE has not received an acknowledgement message corresponding to the packet comprising SI. 
         [0010]    According to the present invention, a communications device of a wireless communications system utilized for timely transmission of a new Scheduling Information (SI) to avoid radio resource waste 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 executing a hybrid automatic repeat request (HARQ) process to transmit a packet comprising SI, and triggering transmission of a new SI when a number of transmissions of the packet comprising SI is greater than or equal to a maximum number of transmissions, and the UE has not received an acknowledgement message corresponding to the packet comprising SI. 
         [0011]    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 
         [0012]      FIG. 1  is a function block diagram of a wireless communications device. 
           [0013]      FIG. 2  is a diagram of program code of  FIG. 1 . 
           [0014]      FIG. 3  is a flowchart of a process according to the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    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. Preferably, the communications device  100  is utilized in a third generation (3G) mobile communications system. 
         [0016]    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  includes an application layer  200 , a Layer 3  202 , and a Layer 2  206 , and is coupled to a Layer 1  218 . The Layer 2  206  comprises two sub-layers: a radio link control (RLC) entity  224  and a media access control (MAC) entity  226 . A primary function of the RLC entity  224  is providing different transmission quality processing, performing segmentation, reassembly, concatenation, padding, retransmission, ciphering, sequence check, and duplication detection on transmitted data or control instructions based on different transmission quality requirements. The MAC entity  226  can match packets received from different logic channels of the RLC entity  224  to common, shared, or dedicated transport channels according to radio resource allocation commands of the Layer 3 (RRC layer)  202 , for performing channel mapping, multiplexing, transport format selection, or random access control. 
         [0017]    In some applications, such as when realizing high-speed uplink packet access (HSUPA) functions, the MAC entity  226  can execute a HARQ process, and retransmit packets based on transmission circumstances and trigger transmission of SI. In this situation, the present invention provides an SI transmission program code  220  utilized for timely triggering of a new SI transmission, in order to avoid radio resource waste, and reduce unnecessary transmissions. Please refer to  FIG. 3 , which is a flowchart diagram of a process  30  according to the present invention. The process  30  is utilized in the UE of the wireless communication system for triggering new SI transmission, comprises the following steps: 
         [0018]    Step  300 : Start. 
         [0019]    Step  302 : Execute an HARQ Process to transmit a packet containing SI. 
         [0020]    Step  304 : Trigger new SI transmission when the number of transmissions, i.e. CURRENT_TX_NB, of the packet containing SI is greater than or equal to a maximum number of transmissions, and the UE has not received an acknowledgement message corresponding to the packet containing SI. 
         [0021]    Step  306 : End. 
         [0022]    According to the process  30 , when the number of transmissions of the packet containing SI by the HARQ process is greater than or equal to the maximum number of transmissions, but the UE has not yet received the acknowledgement message corresponding to the packet containing SI, the HARQ Process will trigger a new SI transmission. Namely, when the status variable CURRENT_TX_NB is greater than or equal to the maximum number of transmissions indicated by the HARQ Profile, and the UE has not yet received an acknowledged message through an E-DCH HARQ Acknowledgement Indicator Channel (E-HICH) from an RLS containing a service cell, the HARQ process will notify an SI reporting function that the HARQ process failed to deliver the triggered SI to the RLS containing the service cell, so as to trigger a new SI transmission. Furthermore, the SI reporting function may require the packet comprising SI to contain multiplexed higher layer data before it triggers a new SI transmission. 
         [0023]    Thus, through the present invention process  30 , the HARQ process triggers the new SI transmission when the UE confirms failure to receive the acknowledgement message corresponding to the last transmission of the packet containing SI. In this way, the HARQ process can avoid unnecessary SI transmission, which increases usage efficiency of the radio resources. 
         [0024]    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.