Method of enhancing continuous packet connectivity in a wireless communications system and related apparatus

IS 2 390 102 T3

DESCRIPTION

A method of improving continuous packet connectivity in a wireless communication system and associated apparatus.

This application claims the benefit of American Provisional Application No. 60 / 868,078, filed on November 30, 2006 and entitled "Procedure and apparatus for improving procedures related to CPC in a wireless communication system".

The present invention relates to a method for improving the discontinuous packet operation used in continuous packet connectivity (CPC) for user equipment and related communication devices according to the preambles of claims 1 and 5.

The third generation (3G) mobile telecommunications system has adopted a Broadband Code Division Multiple Access (WCDMA) wireless air interface access method for a cellular network. WCDMA provides high-frequency spectrum harnessing, universal coverage, and high-speed, high-quality multimedia data transmission. The WCDMA method also meets all types of QoS requirements simultaneously, providing different flexible two-way transmission services and better communication quality to reduce transmission outage rates. Through the 3G mobile telecommunications system, a user can use a wireless communications device, such as a mobile phone, to conduct real-time video communications, conferencing, real-time gaming, online music broadcasts, and sending / receiving email. However, these functions are based on a fast and instantaneous transmission. Thus, focusing on third-generation mobile telecommunications technology, the prior art provides high-speed packet access (HSPA) technology, including high-speed downlink packet access (HSDpA) and high-speed packet access (HSDpA). high speed uplink packets (HSUPA), to increase bandwidth utility rate and packet data processing efficiency to improve uplink / downlink transmission speed. For HSDPA and HSUPA, the 3rd Generation Partnership Project (3GPP) provides a Continuous Packet Connectivity Protocol (CPC) specification that includes features that, for user equipment (UEs) in CELL_DCH state, is intended to significantly increase the number packet data users for a cell, reduce the increase in uplink noise and improve the achievable download capacity for VolP.

For an HSDPA UE, physical channels include a high-speed physical downlink shared channel (HS-PDSCH), for transferring payload data, and a high-speed physical control channel (HS-DPCCH) for load a negative acknowledge / acknowledge (ACK / NACK) and channel quality identifier (CQI). As for the medium control access (MAC) of the HSDPA UE, a MAC-hs entity uses a transport channel of a high speed downlink shared channel (HS-DSCH) to receive data from the physical layer. Furthermore, a shared control channel for HS-DSCH (HS-SCCH) is used as the physical downlink channel, responsible for the transmission of control signals corresponding to HS-DSCH, such as demodulation information.

For an HSUPA UE, the physical channels include two uplink channels: an Enhanced Dedicated Transport Channel (E-DPDCH) dedicated physical data channel, for transferring payload data, and a dedicated E-DCH channel of physical control (E-DPCCH) for the transmission of control signals, such as retransmission numbers. Furthermore, in the HSUPA system, a set of physical downlink channels are used and are used to transmit control signals associated with grants, ACKs and etc. The downlink physical channels include a relative E-DCH grant channel (E-RGCH), an absolute E-DCH grant channel (EaGcH), an E-DCH HARQ confirm indicator channel (E-HICH), and a Fractional Dedicated Physical Channel (F-DPCH). Regarding the MAC layer of the UE HSUPA, a MAC-e / es entity uses a transport channel of an Enhanced Dedicated Transport Channel (E-DCH) for the transmission of MAC packet data to the physical layer with the support of a transmission time interval (TTI) of 10 milliseconds (ms) or 2 ms.

For the CELL_DCH state, the CPC operation defines an active state and an inactive state. For any data channel (eg E-DCH), the active state represents that there are data packets transmitted on the data channels. For any control channel (eg HS-DPCCH), the active state represents that there are data packets transmitted on the data channels corresponding to the control channels, such as HS-PDSCH corresponding to HS-DPCCH. In contrast, for the other data channels, the idle state represents that there are no data packets transmitted on the data channels. For any control channel, the idle state represents that there are no data packets transmitted on the data channels corresponding to the control channels.

According to the CPC protocol specification, discontinuous uplink transmission (DTX uplink) is a mechanism where control signals are transmitted on uplink control channels according to discontinuous patterns defined during the idle state of corresponding uplink data channels in order to maintain signal synchronization and power control loop

ES 2 390 102 T3 with less signaling control. The uplink control channels include a normal DPCCH in addition to the HSUPA and HSDPA uplink control channels mentioned above. The uplink DTX defines two patterns associated with parameters of UE_DTX_cycle_1 and UE_DTX_cycle_2. The first applies depending on the duration of the E-DCH inactivity while the second takes a longer transmission cycle and applies to the inactivity of any uplink control channel. In each UE_DTX_cycle_1 pattern, the UE will not be able to transmit data on DPCCH except for a short burst of UE_DPCCH_burst_1 sub-frames. For example, if UE_DTX_cycle_1 is set to be four E-DPCCH subframes, the UE transmits a short UE_DPCCH_burst_1 burst in the first E-DPCCH subframe and stops DPCCH transmission in the next three E-DPCCH subframes. Furthermore, according to an Inactivity_threshold_for_UE_DTX_cycle_2 parameter, the UE can determine whether to transmit a short burst of UE_DPCCH_burst_2 sub-frames, once each UE_DTX_cycle_2 pattern. UE_DTX_DRX_Offset is used to control the active time of the UE_DTX_cycle_1 / 2 pattern, allowing different UEs to have an uplink transmission phase at different times.

CPC uplink discontinuous reception (uplink DRX) is used to control the UE to transmit E-DCH in a specific time interval and has to be configured with uplink DTX. If there has been no E-DCH transmission for a configurable number of transmission time intervals (for example, the UE_Inactivity_Threshold interval), a radio network controller (RNC) can configure the UE to restrict the start of E- transmission. DCH to a MAC_DTX_cycle pattern. UE_DTX_DRX_Offset is also used in uplink DRX, allowing UEs to have a different E-DCH start time.

CPC's discontinuous downlink reception (downlink DRX) is configured by the RNC and allows the UE to restrict downlink reception times to reduce power consumption. When the downlink DRX is enabled, the UE is not required to receive physical downlink channels except for several specific situations referring to 3GPp TSG-RAN GT2 # 56 R2-063567. If the UE listens for HSSCCH with downlink DRX, the UE receives an HS-SCCH subframe according to subframes of a UE_DRX_cycle pattern. For example, if the UE_DRX_cycle pattern is set to be four HSSCCH sub-frames, the UE receives one HS-SCCH sub-frame and falls into the three subsequent HS-SCCH sub-frames. UE_DTX_DRX_Offset is used to stagger a different HS-SCCH receive start time for different user equipment. Also, the downlink DRX has to be configured with an uplink DTX setting.

Regarding radio resource control (RRC), the UE and the network, such as the Node-B or a radio network controller (RNC), can configure a DTX / DRX operation by exchanging RRC messages and information elements (lEs) that include the parameters and modes mentioned above. In accordance with the 3GPP RRC protocol specification, a Discontinuous Packet Connectivity Timing Information IE is provided to include a number of timing information parameters (for example UE_DTX_DRX_Offset) to delay the start of CPC operation on the reconfiguration and shifting the uplink transmission pattern between different UEs. The timing information can be used to deactivate and activate CPC operation and indicate whether the current CPC parameters are maintained during reconfiguration procedures in order to avoid sending the entire parameter list. Additionally, a DTX-DRX continuous packet connectivity information IE includes settings for UE_DTX_cycle_1 / 2, UE_DPCCH_burst_1 / 2, Inactivity_threshold_for_UE_DTX_cycle_2, MAC_DTX_cycle, and other parameters. The above IEs may be included in RRC CONNECTION SETUP, ACTIVE SET UPDATE, CELL UPDATE CONFIRM, or other reconfiguration messages, and may be transmitted to the UE through RRC procedures. On the other hand, the UE stores the DTX / DRX configuration received in the reconfiguration messages in a variable CPC_DTX_DRX_PARAMS.

In addition, the UE includes a variable CPC_DTX_DRX_STATUS that has two possible values ​​"TRUE and FALSE", representing the in-use state and the out-of-use state of the DTX / DRX operation, respectively. According to the RRC specification, as can be seen in 3FPP TSG-RAN WG2 that complies with # 56 R2-063309 (XP50132792), the UE is required to determine the value for CPC_DTX_DRX_STATUS if it receives any reconfiguration messages. Under the CPC_DTX_DrX_STATUS determination, CPC_DTX_DRX_STATUS will be set to TRUE when all of the following conditions are true:

1. the UE is in the CELL_DCH state;

2. both the HS_DSCH receive and the E_DCH_TRANSMISSION variables are set to TRUE;

3. no DCH transport channel has been configured;

Four. CPC_DTX_DRX_PARAMS is set;

5. the UE has received a Continuous Packet Connectivity Timing Information IE from the last reconfiguration message.

If any of the above conditions are not met and the variable CPC_DTX_DRX_STATUS is set to TRUE, the UE must:

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1. set the variable CPC_DTX_DRX_STATUS to be FALSE;

2. clear the variable CPC_DTX_DRX_PARAMS;

3. stop all related activities of DTX / DRX operation.

Whenever the CPC_DTX_DRX_STATUS variable is set to TRUE, the UE will need to configure the MAC and physical layers to operate according to the CPC_DTX_DRX_PARAMS variable.

Accordingly, the UE determines the value of the CPC_DTX_DRX_STATUS variable only when reconfiguration messages are received, and the DTX / DRX operation applies only to the UE in CELL_DCH. If a radio link failure or unrecoverable radio link control (RLC) error occurs or if transmission of a UE CAPABILITY INFORMATION message fails during DTX / DRX operation, the UE will perform a cell update procedure to remedy those situations. Upon initiating the cell update procedure, the UE shall go to the CELL_FACH state and select a suitable UMTS radio access cell (UTRA) to send a CELL UPDATE message. However, the prior art specification does not specify related actions of DTX / DRX operation under the above-mentioned situations. As a result, the prior art UE does not re-determine the CPC_DTX_DRX_STATUS variable when it exits the CELL_DCH state. That is, the UE continues to apply a DTX / DRX operation in the CELL_FACH state, which is not applicable for a DTX / DRX operation. This can cause serious errors in the physical and MAC layers of the UE. Radio link failure can occur when the UE is in a weak signal distribution area, such as a basement or rural area with poor coverage. The fatal RLC error is likely to occur for many reasons, such as RLC reset errors or rLc recovery errors. The UE CAPABILITY INFORMATION message is used to notify the UTRAN of information about a specific UE capability (eg radio access capability).

With this in mind, the object of the present invention is a method and apparatus for managing the DTX / DRX operation when a user equipment initiates the cell update procedure in a wireless communication system to avoid a malfunction of the system.

This is achieved by a method and apparatus for improving the CPC for a UE in a wireless communication system according to claims 1 and 5. The dependent claims refer to other corresponding developments and improvements.

In the following, the invention is further illustrated by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a functional block diagram of a communication device.

Figure 2 is a diagram of the program code shown in Figure 1.

Figure 3 is a flow chart of a method in accordance with one embodiment of the present invention.

Reference is made to Figure 1, which is a functional block diagram of a communication device 100. For brevity, Figure 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 communication device 100. In communications device 100, control circuit 106 executes program code 112 in memory 110 through CPU 108, thereby controlling an operation of communications device 100. Communications device 100 can receive sent signals by a user through input device 102, such as a keyboard, and can send images and sounds through output device 104, such as a monitor or speakers. Transceiver 114 is used to receive and transmit wireless signals, sending received signals to control circuit 106, and sending signals generated by control circuit 106 wirelessly. From a communications protocol framework perspective, transceiver 114 can be viewed as a Layer 1 part, and control circuit 106 can be used to perform Layer 2 and Layer 3 functions. Preferably, the communication device 100 is used in a third generation (3G) mobile communication system high speed packet access (HSPA) system, which supports continuous packet connectivity (CPC).

Reference is still made to Figure 2. Figure 2 is a diagram of the program code 112 shown in Figure 1. Program code 112 includes an application layer 200, a Layer 3 202, and a Layer 2 206 , and is connected to a Layer 1 218. Layer 3 202 includes a radio resource control (RRC) entity 222, which is used to control Layer 1 218 and Layer 2 206 and performs point-to-point RRC communication with other communication devices, such as a node-B or a UTRAN. Furthermore, the RRC entity 222 may change an RRC state of the communication device 100, switching between a standby mode, a CELL_PCH, URA_PCH, CELL_FACH or CELL_DCH state.

Layer 2 206 includes a radio link control (RLC) and a medium access control (MAC) layer, and Layer 1 218 is the physical layer. When the HSDPA is in use, the MAC layer listens to the HS-SCCH for reception of HS-DSCH signals and therefore receives data packets by listening to HS-DSCH. In addition, HS-PDSCH and HS-DPCCH are used for the exchange of payload data between the communication device 100 and the network. When the

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HSUPA is in use, the MAC layer transmits the packets through E-DCH, while the physical layer exchanges payload data and control signals related to Node-B or UTRAN through E-DPDCH, E- DPCCH, E-RGCH, E-AGCH, E-HICH and F-DPCH.

A network communications device can form RRC messages and information elements (IEs) to transmit a CPC configuration to the communications device through radio bearers 100. Reconfiguration messages, such as the RRC RECONNECTON SETUP message, ACTIVE SET UPDATE or CELL UPDATE CONFIRM can include CPC DTX / DRX operation parameters, where DTX / DRX is well known as discontinuous transmission / reception. Accordingly, the communications device 100 stores received parameters in a variable CPC_DTX_DRX_PARAMS and thus varies the operation of Layer 2 206 and Layer 1 218. In addition, the communications device 100 includes a variable CPC_DTX_DRX_STATUS that has two values possible TRUE and FALSE representing an in-use state and an out-of-use state of the DTX / DRX operation, respectively.

In this situation, the embodiment of the present invention provides a discontinuous packet operation management program code 220 for program code 112 to prevent a system malfunction when the UE initiates a cell update procedure during operation. discontinuous packet. Reference is made to Figure 3, which illustrates a schematic diagram of a process 30 in accordance with one embodiment of the present invention. Process 30 is used for managing a CPC discontinuous packet operation for a UE in a wireless communication system, and can be compiled into the discontinuous packet operation management program code 220. Process 30 includes the following stages:

Stage 300: Start.

Step 302: Activate a discontinuous packet operation according to a state variable. Step 304: Re-determine the state variable and take corresponding actions when a cell update procedure is started.

Stage306: End.

In process 30, the packet discontinuous operation is preferably a CPC DTX / DRX operation, including uplink discontinuous transmission (uplink DTX), uplink discontinuous reception (uplink DRX), and downlink discontinuous reception (downlink DRX). The state variable is preferably a CPC_DTX_DRX_STATUS variable. When the variable CPC_DTX_DRX_STATUS is set to TRUE, the DTX / DRX operation is activated. When a radio link failure or an unrecoverable RLC error occurs or when the transmission of a UE CAPABILITY INFORMATION message fails during DTX / DRX operation, the cell update procedure is triggered to remedy those situations. When the cell update procedure is started, the UE goes to the CELL_FACH state for the selection of a suitable UTRA cell and furthermore, the CPC_DTX_DRX_STATUS variable is re-determined by determining if all the conditions mentioned above are met to establish that the variable CPC_DTX_DRX_STATUS is TRUE. Since the UE no longer remains in the CELL_DCH state, the conditions required by setting the variable CPC_DTX_DRX_STATUS to be TRUE are not all met. The UE then performs the corresponding actions, including:

1. set the variable CPC_DTX_DRX_STATUS to be FALSE if the variable CPC_DTX_DRX_STATUS is originally programmed to be TRUE;

2. delete the variable CPC_DTX_DRX _PARAMS;

3. stop all related activities of DTX / DRX operation, such as stopping discontinuous transmission of HS-DPCCH belonging to uplink DTX, stopping discontinuous reception of E-DCH belonging to uplink DRX, or stopping discontinuous reception of HS-SCCH belonging to downstream DRX.

Through the above actions, the DTX / DRX operation can be stopped successfully when the cell update procedure starts.

Furthermore, an alternative of stopping the DTX / DRX operation is to perform the above-mentioned actions directly without re-determining the CPC_DTX_DRX_STATUS variable after the UE has selected a suitable UTRA cell during the cell update procedure. In this way, when a radio link failure or an unrecoverable RLC error occurs or when the transmission of a UE CAPABILITY INFORMATION message fails, the UE can stop a DTX / DRX operation of the physical and MAC layers in time to avoid a bad system operation.

In conclusion, the embodiment of the present invention specifies that the UE stops the DTX / DRX operation when a radio link failure or an unrecoverable RLC error occurs or when the transmission of a UE CAPABILITY INFORMATION message fails.