Abstract:
A method of receiving system information for a user equipment, hereinafter called UE, of a wireless communications system is provided to prevent a connection loss between the UE and a network terminal. The UE uses a dedicated HS-DSCH radio network transaction identifier, abbreviated to H-RNTI, for a high speed downlink operation in a CELL_PCH state. The method includes receiving a radio resource control message used for providing modification indication of the system information via a broadcast control channel.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/916,300, filed on May 06, 2007 and entitled “Method And Apparatus for Reception of Paging on HS-DSCH for the UE in CELL_PCH State in a Wireless Communication System”, 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 a method of receiving system information for a wireless communications system and related communications device, and more particularly to a method of receiving modification indication of system information for a user equipment in a CELL_PCH state in a wireless communications system and related communications device. 
         [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 at the third generation mobile telecommunication technology, the 3rd Generation Partnership Project (3GPP) provides High Speed Package Access (HSPA) technology, which includes High Speed Downlink Package Access (HSDPA) and High Speed Uplink Package Access (HSUPA), to increase bandwidth utility rate and package data processing efficiency to improve uplink/downlink transmission rate. 
         [0006]    On the basis of HSDPA, the 3GPP further introduces HS-DSCH (High Speed Downlink Shared Channel) reception in a CELL_PCH and a URA-PCH state, allowing the UE in the CELL_PCH or the URA-PCH state to monitor an HS-DSCH accompanied with a Shared Control Channel for HS-DSCH (HS-SCCH) for downlink data reception, so as to improve a peak data rate, a signaling delay, a state transition delay, download times and flexible cell capacity. In the HS-DSCH reception in the CELL_PCH and URA_PCH state, the HS-DSCH is a transport channel allowed to map on dedicated-type logic channels including a Dedicated Control Channel (DCCH) and a Dedicated Traffic Channel (DTCH) or common-type logic channels including a Paging Control Channel (PCCH) and a Broadcast Control Channel (BCCH). 
         [0007]    A UMTS radio access network (UTRAN) enables the HS-DSCH reception in the CELL_PCH and the URA_PCH state by including parameters, related to radio resource control (RRC) configuration of PICH (Paging Indicator Channel), HS-SCCH, HS-DSCH and an H-RNTI (HS-DSCH radio network transaction identifier) for PCCH transmission, in the system information broadcast. The parameters are configured in a “HS-DSCH paging system information” information element (IE) included in a system information block (SIB) type 5/5bis sent from the UTRAN to the UE. 
         [0008]    During performance of the HS-DSCH reception in the CELL_PCH and the URA_PCH state, the UE may use a common or a dedicated H-RNTI as a UE identity for reception of HS-DSCH packets. 
         [0009]    The common H-RNTI can be shared by multiple UEs, whereas each dedicated H-RNTI is only allocated to one UE. During reception of downlink media access control (MAC) packets, the UE using the common H-RNTI needs to determine whether the received packets are of its own with UE identification information (i.e. UE ID and UE ID Type) in the packet header. On the other hand, the MAC packets for the UE using the dedicated H-RNTI include no UE identification information to provide better data transmission efficiency. As a result, PCCH reception requires the common H-RNTI, and DCCH and DTCH receptions require the dedicated H-RNTI. Furthermore, with the available HS-DSCH reception, the UE using the dedicated H-RNTI in the CELL_PCH state can perform downlink and uplink data transmissions without a cell update procedure. 
         [0010]    When the UTRAN allocates a dedicated H-RNTI to the UE, the UE stores the dedicated H-RNTI in an H-RNTI variable. In addition, when the UE is in the CELL_PCH state and the SIB type 5/5bis includes the “HS-DSCH paging system information” IE, the UE has to use the dedicated H-RNTI for the HS-DSCH reception if the H-RNTI variable is set, otherwise the UE selects the common H-RNTI to use from the “HS-DSCH paging system information” IE. 
         [0011]    A PAGING TYPE  1  and a PAGING TYPE  2  message are RRC messages provided in the related RRC specification for paging operation. The former is applied to the UE in an idle mode, a CELL_PCH state, or a URA_PCH sate and sent on the PCCH for notifying the UE of general paging information corresponding to modification indication of SIBs or a terminating call. The latter is applied to the UE in a CELL_FACH or a CELL_DCH state and sent on DCCH for notifying the UE of dedicated paging information. 
         [0012]    When the SIB configuration needs to be modified, the UTRAN includes a “BCCH modification info” IE in the PAGING TYPE  1  message and sends the PAGING TYPE  1  message on the PCCH. However, the UE selects either the common or dedicated H-RNTI to use according to the state of the H-RNTI variable. That is to say, the UE cannot use the common and dedicated H-RNTIs simultaneously. Consequently, the UE using the dedicated H-RNTI cannot receive the PAGING TYPE  1  message sent on the PCCH. 
         [0013]    According to the prior art, a UE in the CELL_PCH state counts on the paging information on the PCCH for the modification indication of the SIBs. But the UE using the dedicated H-RNTI in the CELL_PCH state cannot receive any paging information on the PCCH, possibly resulting in a connection loss between the UE and the UTRAN. 
       SUMMARY OF THE INVENTION  
       [0014]    The present invention therefore provides a method of receiving modification indication of system information for a UE using a dedicated H-RNTI in a CELL_PCH state in a wireless communications system and related communications device that can avoid a connection loss between the UE and a network terminal. 
         [0015]    The present invention discloses a method of receiving system information for a UE of a wireless communications system. The UE uses a dedicated H-RNTI for a high speed downlink operation in a CELL_PCH state. The method includes receiving a radio resource control message used for providing modification indication of the system information via a broadcast control channel. 
         [0016]    The present invention further discloses a communications device in of a wireless communications system for receiving system information to prevent a connection loss. The communications device uses a dedicated H-RNTI for a high speed downlink operation in a CELL_PCH state and includes a control circuit, a processor and a memory. The control circuit is used for realizing functions of the communications device. The processor is installed in the control circuit and used for executing a program code to command the control circuit. The memory is installed in the control circuit and coupled to the processor, and used for storing the program code. The program code includes receiving a radio resource control message used for providing modification indication of the system information via a broadcast control channel. 
         [0017]    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 
         [0018]      FIG. 1  is a schematic diagram of a wireless communications system. 
           [0019]      FIG. 2  is a functional block diagram of a communications device. 
           [0020]      FIG. 3  is a diagram of the program code shown in  FIG. 2 . 
           [0021]      FIG. 4  is a flowchart diagram of a process according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0022]    Please refer to  FIG. 1 , which is a schematic diagram of a wireless communications system  10 . The wireless communications system  10  is preferred to be a high-speed packet access (HSPA) system of a third generation (3G) mobile communications system, and is briefly formed with a network terminal and a plurality of user equipments. In  FIG. 4 , the network terminal and the user equipments are simply utilized for illustrating the structure of the wireless communications system  10 . Practically, the network terminal may include a plurality of base stations, radio network controllers and so on according to actual demands, and the user equipments (UEs) can be apparatuses such as mobile phones, computer systems, etc. 
         [0023]    Please refer to  FIG. 2 , which is a functional block diagram of a communications device  100 . The communications device  100  can be utilized for realizing the UEs in  FIG. 1 . For the sake of brevity,  FIG. 2  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 HSPA system of a third generation (3G) mobile communications system and supports a high speed downlink operation corresponding to a CELL_PCH state, including HS-DSCH reception in the CELL_PCH state. 
         [0024]    Please continue to refer to  FIG. 3 .  FIG. 3  is a diagram of the program code  112  shown in  FIG. 2 . 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  3   202  includes a radio resource control (RRC) entity  222  for controlling the Layer  1218  and the Layer  2   206  with RRC messages and information elements (IEs) and performing peer-to-peer communication with the network terminal. In addition, the RRC entity  222  can switch the communications device  100  among the idle mode, the CELL_PCH, the URA_PCH, the CELL_FACH, or the CELL_DCH state. The Layer  2   206  includes a radio link control (RLC) layer and a media access control (MAC) layer, which exchange packets via logic channels. In addition, the MAC layer exchanges MAC packets with the Layer  1   218  via transport channels, whereas the Layer  1   218  exchanges radio signals with the network terminal of the wireless communications system  10 . Under the HS-DSCH reception in the CELL_PCH state, the associated logic channels include the DTCH, DCCH, PCCH and BCCH. The associated transport channels include the HS-DSCH used for dedicated packet transmission accompanied with signaling transmission of an HS-SCCH (physical channel). 
         [0025]    The communications device  100  can use a common or dedicated H-RNTI for the high speed downlink operation. When the communications device  100  performs the high speed downlink operation in the CELL_PCH state with the dedicated H-RNTI, the embodiment of the present invention provides an information modification indication receiving program code  220  in the program code  112  to avoid a connection loss due to inability to receive modification indication of system information. Please refer to  FIG. 4 , which illustrates a schematic diagram of a process  40  according to an embodiment of the present invention. The process  40  is utilized to receive system information for a UE of a wireless communications system, and can be compiled into the information modification indication receiving program code  220 . The process  40  includes the following steps: 
         [0026]    Step  400 : Start. 
         [0027]    Step  402 : Receive an RRC message used for providing modification indication of the system information via a broadcast control channel. 
         [0028]    Step  404 : End. 
         [0029]    According to the process  40 , the UE not only uses the dedicated H-RNTI for reception of signaling and data on the DTCH and DCCH, but also receives the RRC message used for providing the modification indication of the system information via the broadcast control channel (BCCH). Preferably, the UE monitors the BCCH to receive the RRC message according to a BCCH specific H-RNTI. 
         [0030]    Preferably, the BCCH is a logic channel mapped to the HS-DSCH. The RRC message is a SYSTEM INFORMATION CHANGE INDICATION message including a BCCH modification info IE. In this situation, the UE receives the BCCH specific H-RNTI and a channelization code set related to the HS-DSCH from the SIB type 5/5bis broadcasted by the network terminal, and thereby monitors the BCCH to receive the BCCH modification info IE for modifying the system information. 
         [0031]    In the prior art, the UE is unable to receive the modification indication of the system information when the UE performs the HS-DSCH reception in the CELL_PCH state with the dedicated H-RNTI. In the embodiment of the present invention, the UE can receive the modification indication of the system information via the BCCH to avoid the connection loss. 
         [0032]    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.