CN1173504C - Transmission control method for high-speed data service when serving cell changes - Google Patents

Abstract

The invention discloses a transmission control method for high-speed data services when a serving cell is changed. The method includes: RNC sends a PDU data packet to a source cell and a candidate cell at the same time; Notify the candidate cell of the segmentation scheme and coding and modulation scheme, and the candidate cell performs the same segmentation, coding and modulation on the PDU data packet as the source cell according to the received segmentation scheme and coding and modulation scheme, so that both the source cell and the candidate cell retain the same PDU The data packet and the corresponding TB, when the cell update occurs, one of the candidate cells is upgraded to the target serving cell, and the source serving cell is downgraded to a candidate cell or a neighboring cell, so that the UE can retransmit from the source when some TB retransmissions are not completed. The transmission of data is not interrupted in the process of updating the cell to the target cell, so the present invention can reduce the transmission delay of the high-speed data service when the serving cell is changed, and improve the transmission efficiency of the high-speed data service.

Description

Transmission control method for high-speed data service when serving cell changes

technical field

The invention relates to a high-speed data transmission method in a wireless communication system, in particular to a high-speed data service transmission control method when a serving cell is changed.

Background technique

In the Wideband Code Division Multiple Access (WCDMA) system, in order to enable mobile users to obtain a large number of services such as downloading files as wired Internet users, High Speed Downlink Packet Access (HSDPA, High Speed Downlink Packet Access) is adopted Technology, the main channel for data transmission is HS-DSCH (High Speed Downlink Shared Channel, High Speed Downlink Shared Channel). In this channel, the frequently transmitted data are Web (web page) browsing, FTP (File Transfer Protocols, file transfer protocol) downloading and other services. Since some services require data transmission to ensure a certain delay quality, reducing the data transmission delay is an important part of ensuring the quality of data reception. In the process of high-speed data transmission, the time delay generated by the switching process of the serving cell is an important factor affecting the quality of data reception. During high-speed data transmission, if the serving cell changes, it is necessary to synchronize the PDU information of the new and old serving cells before continuing data transmission. A better transmission control method for existing high-speed data services when the serving cell is changed is that when the source serving cell receives an instruction to change the cell, the source serving cell performs the operation according to the high-speed media control layer (MAC-hs) queue. PDU transmission status, generate a mapping, that is, a bitmap with the length of the PDU queue, each bit uses 1/0 to indicate the status of a PDU transmission success in the PDU queue, and then reports the mapping to the wireless network control controller (RNC). The RNC decides which data to send to the new serving cell according to the mapping. The main problem of this method is that unsent PDUs must be forwarded by RNC before reaching the target serving cell, so the transmission delay of the interface (Iur/Iub interface) between the RNC and the base station and between the RNCs and the RNC's dependence on the mapping information Any processing delay will bring obvious lag to the downlink transmission of the new serving cell.

Contents of the invention

The object of the present invention is to provide a transmission control method for high-speed data services when the serving cell is changed, the method can reduce the transmission delay of the high-speed data services when the serving cell is changed, and improve the transmission efficiency of the high-speed data services.

In order to achieve the above object, the transmission control method of the high-speed data service provided by the present invention when the serving cell is changed includes:

(1) The radio network controller (RNC) determines the candidate cell of the user equipment (UE);

(2) The RNC sends a protocol data unit (PDU) packet to the source serving cell and the candidate serving cell at the same time;

(3) The media access control layer (MAC) scheduling entity of the source serving cell divides the PDU data packet into a transmission data block (TB), encodes and modulates the TB and sends it to the UE, and at the same time divides the PDU data packet segmentation scheme and The coding and modulation scheme informs the candidate serving cell, and the candidate serving cell performs the same segmentation and coding and modulation on the PDU data packet as the source serving cell by the MAC scheduling entity according to the received segmentation scheme and coding and modulation scheme;

(4) The Hybrid Automatic Repeat (HARQ) entity of the UE demodulates and decodes the received TB, and feeds back the reception quality information to the source cell and the candidate cell according to the demodulation and decoding results;

(5) RNC judges whether the cell update operation takes place at the current moment, if it occurs, turn to step (6), otherwise turn to step (7);

(6) The RNC upgrades the candidate cell to the target cell, and downgrades the source serving cell to a candidate cell or an adjacent cell. The target cell judges whether the TB transmission is successful according to the reception quality information fed back by the UE. If it fails to resend, when the target cell MAC After all the TBs corresponding to the PDU data packets are successfully sent, the target cell deletes the PDU data packets; at the same time, the candidate serving cell judges whether the TB is successfully sent according to the reception quality information fed back by the UE. After successfully sending, the candidate serving cell deletes the PDU packet, and then turns to step (8);

(7) The source serving cell judges whether the TB is successfully sent according to the receiving quality information fed back by the UE. If it is unsuccessful and resends, when the TB corresponding to the PDU data packet of the source serving cell MAC is successfully sent, the source serving cell deletes the PDU data packet , at the same time, the candidate serving cell judges whether the TB is sent successfully according to the receiving quality information fed back by the UE. After all the TBs corresponding to the PDU packets of the MAC of the candidate serving cell are successfully sent, the candidate serving cell deletes the PDU packet, and then turns to step (8 );

(8) The radio link control layer (RLC) of the UE feeds back the receiving quality information according to the received PDU data packet, and the RLC of the source serving cell, the candidate serving cell and the target serving cell judge the PDU data packet according to the receiving quality information fed back by the RLC of the UE Whether the transmission is successful, if successful, delete the respective successfully transmitted RLC PDU data packets, and the cell update ends.

In the above step (2), the RNC simultaneously delivers PDU data packets to the source serving cell and the candidate serving cell based on clock synchronization.

Described step (3) also comprises:

The source serving cell determines the coding and modulation scheme of the divisor data according to the conditions of the transmission channel, so as to code and modulate the TB to be sent.

A one-way direct transmission channel is established between the MACs of the source serving cell and the candidate cell, so that the MAC scheduling entity of the source serving cell notifies the candidate cell of the division scheme and coding and modulation scheme of the PDU data packet.

The above establishment of a one-way direct transmission channel between the MAC of the source serving cell and the MAC of the candidate cell can also be replaced by establishing a mapping relationship from the MAC PDU to the TB of the source serving cell, so that the candidate cell can analyze the mapping from the MAC PDU to the TB according to the above mapping relationship , to complete the division, coding and modulation of the same PDU data packet as that of the source serving cell.

The feedback receiving quality information in the steps (4), (6), (7) and step (8) is feedback confirmation or non-acknowledgment information (ACK or NACK).

In the present invention, since the RNC sends the protocol data unit (PDU) packet to the source serving cell and the candidate serving cell simultaneously, the media access control layer (MAC) scheduling entity of the source serving cell sends the PDU packet Notify the candidate serving cell of the segmentation scheme and coding and modulation scheme, and the candidate serving cell performs the same segmentation and coding and modulation on the PDU data packet as the source serving cell by the MAC scheduling entity according to the received segmentation scheme and coding and modulation scheme. In this way, the source serving cell Both the candidate serving cell and the candidate serving cell retain the same PDU data packet and the corresponding TB. Once the serving cell update occurs, one of the candidate cells is upgraded to the target serving cell, and the source serving cell is downgraded to a candidate cell or a neighboring cell, so that the UE can be in Some TB retransmissions are not interrupted during the process of updating from the source serving cell to the target serving cell, so the present invention can reduce the transmission delay of high-speed data services when the serving cell is changed, and improve the transmission efficiency of high-speed data services .

Description of drawings

Fig. 1 is the embodiment flowchart of the inventive method;

Figure 2 is a logic diagram of data flow control during high-speed data transmission.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

The essence of the present invention is that when HSDPA updates the serving cell, the source serving cell informs the target serving cell of the current physical layer data transmission status through signaling, and the target serving cell obtains the state of the source serving cell and the ACK or ACK fed back by the UE. NACK uplink signaling to process the PDU queue so that the serving cell can be updated in time.

In the specific data transmission process, the PDU data packet of the radio link control layer (RLC layer) is sent to the MAC layer, and then is split and assembled into TB by the scheduling entity, and then encoded and modulated to the wireless air interface for transmission. After receiving the data, the receiving party undergoes demodulation and decoding, and the TB block is restored, and can judge whether the TB is correct through the check code (usually the cyclic redundancy check code CRC: Cyclic Redundancy Code) in the TB block. If it is wrong, Then the UE sends uplink non-acknowledgment information NACK through the feedback channel, and the base station side receives the NACK to resend the TB; if it is correct, the UE sends the confirmation information ACK through the feedback channel, and the base station side receives the ACK to send the next new TB, refer to Figure 2 .

Based on the above facts, reference is made to FIG. 1 for a specific embodiment of the transmission control method for high-speed data services provided by the present invention when the serving cell is changed. In the first step, the radio network controller (RNC) determines the candidate cell of the user equipment (UE), and the candidate cell is a cell where the received signal from the UE is strong enough to establish normal communication. After determining the candidate cell of the UE, in the second step, the RNC sends PDU data packets to the source serving cell and the candidate serving cell simultaneously based on clock synchronization. That is to say, the PDU data packets obtained by the MACs of the source serving cell and the candidate serving cell are the same. After receiving the PDU packet, carry out step 3, the source serving cell determines the encoding and modulation scheme of the transmission data according to the condition of the transmission channel, then, the media access control layer (MAC) scheduling entity of the source serving cell divides the PDU packet into Transmit data block (TB), encode and modulate the TB and send it to the UE. At the same time, establish a one-way direct transmission channel between the MACs of the source serving cell and the candidate cell, and divide the PDU packet segmentation scheme and coding modulation The scheme informs the candidate serving cell, and the MAC scheduling entity performs the same segmentation, coding and modulation on the PDU data packet stored in the candidate serving cell as the source serving cell according to the division scheme and coding and modulation scheme of the received PDU data packet. Through the above operations, the MAC layer in the candidate cell stores the PDU data packets obtained through the high-speed downlink shared channel. Before the serving cell is changed, the candidate cell performs the same TB separation and coding modulation on it according to the signaling of the source serving cell, but Not sent over the wireless channel.

In the above step 3, there may be no signaling from the MAC of the source serving cell to the MAC of the candidate cell. As long as the mapping relationship between the MAC PDU of the source serving cell and the TB is established in advance, the candidate cell can analyze the MAC PDU to TB according to the rules The mapping relationship between the MAC PDU and the TB of the source serving cell is no longer required to be known through signaling. Because the UE is usually at the edge of the cell when the serving cell is changed, and the signal is relatively weak, usually the signal transmitted by the base station to the UE on the high-speed downlink shared channel (HS-DSCH) can use the lowest coding and modulation rate, so the MAC PDU to The mapping of TB is easier to fix. Therefore, the candidate serving cell can complete the segmentation, coding and modulation of the same PDU data packet as the source serving cell according to the above mapping relationship.

The synchronization between the candidate serving cell and the source serving cell can be divided into two layers. The first layer judges whether the TB is successfully transmitted according to the received quality information received from the physical layer HARQ feedback of the UE, and then deletes or reserves the queue of the TB; The second layer is the RLC layer, according to the receiving quality information of the PDU data packet fed back by the peer-to-peer RLC layer of the UE (this part of the information is fed back to the RLC on the base station side through the dedicated signaling channel), and the relevant PDU queue is reserved for retransmission or deleted. . Therefore, both the source serving cell and the candidate serving cell retain the same PDU and corresponding TB. Once the serving cell update occurs, one of the candidate cells is upgraded to the target serving cell, and the source serving cell is downgraded to a candidate cell or an adjacent cell. With this synchronization method, the UE can update from the source serving cell to the target serving cell without interrupting the data transmission when the retransmission of some TBs is not over. The new target serving cell decides whether to resend the reserved TB with the same modulation code or to send a new TB data block according to the receiving quality information fed back by the UE.

Therefore, in the fourth step of the present invention, the hybrid automatic repeat (HARQ) entity of the UE demodulates and decodes the received TB, and feeds back the receiving quality information to the source cell and the candidate cell according to the demodulation and decoding results. Then in step 5, the RNC judges whether a cell update operation occurs at the current moment, and if it occurs, proceed to step 6, the RNC upgrades the candidate cell to the target cell, and downgrades the source serving cell to a candidate cell or an adjacent cell, and the target cell receives feedback from the UE The quality information judges whether the TB is sent successfully. If it is not successful and resends, when the TB corresponding to the PDU data packet of the MAC of the target cell is successfully sent, the target cell deletes the PDU data packet. At the same time, the candidate serving cell Determine whether the TB is successfully sent. When the TBs corresponding to the PDU data packets of the MAC of the candidate serving cell are successfully sent, the candidate serving cell deletes the PDU data packet, and then proceeds to step 8 to continue execution; otherwise, proceed to step 7. The received quality information of the TB judges whether the TB is successfully sent. If it is unsuccessful and resent, when the TB corresponding to the PDU data packet of the MAC is successfully sent, the PDU data packet is deleted. At the same time, the candidate serving cell judges according to the received quality information fed back by the UE. Whether the TB is sent successfully, when the TB corresponding to the PDU data packet of the MAC is successfully sent, delete the PDU data packet, and then perform step 8. In step 8, the radio link control layer (RLC) of the UE feeds back the receiving quality information according to the received PDU data packet, and the RLCs of the source serving cell, the candidate serving cell and the target serving cell judge the PDU data according to the receiving quality information fed back by the RLC of the UE Whether the packet is sent successfully, if successful, delete the respective RLC PDU data packets sent successfully, so far, the cell update ends.

It should be noted that, in this embodiment, the received quality information fed back in steps 4, 6, 7 and 8 above is feedback acknowledgment or non-acknowledgement information (ACK or NACK).

The key requirement of the present invention is that the time for the signaling of the MAC layer of the source serving cell to arrive at the candidate cell is small enough to satisfy one HARQ process time. Usually a HARQ process is 4 to 6 transmission time intervals (TTI), currently the TTI of HSDPA is 2ms, that is to say, the signaling direct transmission time from the MAC of the source serving cell to the MAC of the candidate serving cell should be less than 8ms~12ms, This is relatively easy to satisfy for the prior system. If the two cells are located in the same base station, the delay will be smaller.

If the signaling transmission delay is greater than the above requirement, the signaling can be reduced by constraining the change frequency of the PDU segmentation scheme of the source serving cell and the corresponding modulation and coding mode. For example, constraining the TB and modulation codes in two consecutive TTIs to be the same can reduce the signaling by half, double the period, and have little impact on transmission.

In a word, for high-speed data services, the present invention can make the transmission of service data in the state of seamless continuous transmission.

Claims (6)

1, the transfer control method of a kind of high-speed data service when Serving cell changes comprises:

(1) radio network controller (RNC) is determined the candidate cell of subscriber equipment (UE);

(2) RNC issues protocol Data Unit (PDU) packet simultaneously to source Serving cell and candidate service sub-district;

(3) MAC layer of source Serving cell (MAC) scheduling entity is divided into transmission data block (TB) with the PDU packet, described TB is carried out issuing UE after the coded modulation, with the splitting scheme and the coded modulation scheme notice candidate service sub-district of PDU packet, the candidate service sub-district is carried out and same the cutting apart and coded modulation of source Serving cell the PDU packet by the MAC scheduling entity according to the splitting scheme and the coded modulation scheme that receive simultaneously;

(4) mixing of UE retransmits (HARQ) entity automatically the TB that receives is carried out the demodulation sign indicating number, and according to the result of demodulation sign indicating number to cell-of-origin and candidate cell feedback reception quality information;

(5) RNC judges whether current time the cell update operation takes place, if step (6) takes place to change, otherwise changes step (7);

(6) RNC makes candidate cell rise to Target cell, the source Serving cell is downgraded to candidate cell or neighbor cell, Target cell judges according to the reception quality information of UE feedback whether TB sends success, if unsuccessful resending, after the TB of the PDU of Target cell MAC packet correspondence successfully sent, Target cell was deleted this PDU packet; Simultaneously, the candidate service sub-district judges according to the reception quality information of UE feedback whether TB sends success, and as the TB of the PDU packet correspondence of candidate service sub-district MAC all successfully after the transmission, this PDU packet is deleted in the candidate service sub-district, changes step (8) then;

(7) the source Serving cell judges according to the reception quality information of UE feedback whether TB sends success, if unsuccessful resending, after the TB of the PDU packet correspondence of source Serving cell MAC successfully sends, the source Serving cell is deleted this PDU packet, simultaneously, the candidate service sub-district judges according to the reception quality information of UE feedback whether TB sends success, after the TB of the PDU packet correspondence of candidate service sub-district MAC successfully sends, this PDU packet is deleted in the candidate service sub-district, changes step (8) then;

(8) wireless chain control layer of UE (RLC) is according to the PDU packet feedback reception quality information that receives, the RLC of source Serving cell, candidate service sub-district and target serving district judges according to the reception quality information of the RLC feedback of UE whether the PDU packet sends success, if success, delete the RLC PDU packet of transmission success separately respectively, cell update finishes.

2, the transfer control method of high-speed data service according to claim 1 when Serving cell changes is characterized in that in described step (2), RNC issues the PDU packet to source Serving cell and candidate service sub-district simultaneously based on clock synchronization mode.

3, the transfer control method of high-speed data service according to claim 1 when Serving cell changes, it is characterized in that described step (3) also comprises: the source Serving cell is according to the definite coded modulation scheme that removes logarithmic data of the condition of transmission channel, so that the TB that will send is carried out coded modulation.

4, the transfer control method of high-speed data service according to claim 1 when Serving cell changes, it is characterized in that described step (3) also comprises: between the MAC source Serving cell and candidate cell, set up the unidirectional channel that direct transfers, so that the MAC scheduling entity of source Serving cell will be to the splitting scheme and the coded modulation scheme notice candidate cell of PDU packet.

5, the transfer control method of high-speed data service according to claim 1 when Serving cell changes, it is characterized in that described step (3) also comprises: set up the mapping relations of source Serving cell MAC PDU to TB, so that candidate cell is separated the mapping of parsing MAC PDU to TB according to above-mentioned mapping relations, finish cutting apart and coded modulation of the PDU packet identical with the source Serving cell.

6, the transfer control method of high-speed data service according to claim 1 when Serving cell changes is characterized in that the feedback reception quality information in described step (4), (6), (7) and the step (8) is feedback acknowledgment or unacknowledged information (ACK or NACK).

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