KR100365185B1 - A method and an apparatus for receiving packet data using re-encoding on physical layer to support combine in W-CDMA system - Google Patents

Abstract

The present invention provides a soft combine performance at a receiving side in asynchronous mobile communication system such as a wideband code division multiple access (W-CDMA) system or an asynchronous IMT-2000 system when data is transmitted using hybrid ALQ type II / III. A method and apparatus for applying a soft combine using physical layer recoding in an asynchronous mobile communication system, the method comprising: recovering a transport block through rate matching, channel decoding, segmentation / combination of received data symbols, A first step of performing error checking on the recovered transport block; A second step of performing inverse segmentation / channel encoding by segmentation / combining and storing the transport block in which an error is detected; And recovering the transport block through rate matching, channel decoding, segmentation / combination of the re-received data symbols, and performing reverse recombination and channel encoding by segmentation / combination on the recovered transport block to perform the stored transmission. And a third step of performing a soft combine with the block. The inverse recombination and channel encoding process is performed only when the coding start point offset of the corresponding transport block is not an initial value. Solve the problem of coding offset mismatch.

Description

A method and an apparatus for receiving packet data using re-encoding on physical layer to support combine in W-CDMA system

The present invention relates to a method and apparatus for applying soft combine using physical layer recoding in an asynchronous mobile communication system. More particularly, the present invention relates to asynchronous mobile communication such as a wideband code division multiple access (W-CDMA) system or an asynchronous IMT-2000 system. In the communication system, the physical layer in the asynchronous mobile communication system to improve the soft combine performance on the receiving side when transmitting data by applying Hybrid ARQ (hereinafter referred to as HARQ) type II / III A method and apparatus for applying a soft combine using recoding.

HARQ mechanism combines the channel coding mechanism and the ARQ mechanism to maximize the transmission efficiency on the channel. To this end, various types of encoding methods and ARQ mechanisms are used, and HARQ types are distinguished according to their application methods. HARQ type I is a scheme in which coding and ARQ operate independently in separate layers, and HARQ type II / III performs soft combine at the physical layer for more efficient transmission.

Soft combine combines retransmission data block with previous error data block to recover symbol level error in the physical layer, generates new data symbol block and decodes it. to be. In order to increase the efficiency of the soft combine, it must be able to identify whether the data blocks received at the physical layer are initial transmission data blocks or retransmission data blocks, and in the case of retransmission data blocks, the same information as the previously transmitted data transmission blocks. Must be coded.

The physical layer on the transmitting side performs concatenation / segmentation to improve the efficiency of the encoder for the data blocks transmitted from the upper layer. This has the advantage of being able to use the encoder efficiently, but the data block of the upper layer can be divided and transmitted in the form of combined with other data blocks, so that CRC check in data transmission block unit and retransmission based on it It is not possible to guarantee that the transmission symbol of the data block actually transmitted in the physical layer is the same as the symbol of the same type as the initial transmission.

In conclusion, in order to enable soft combine, the problem that the transmission symbol generated after the encoding process in the physical layer has the same type of information as the previous initial transmission must be solved urgently.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is a mismatch problem of coding offsets generated on soft combines in applying HARQ type II / III required for efficient data transmission in an asynchronous mobile communication system. It is an object of the present invention to provide a method and apparatus for applying a soft combine using physical layer recoding in an asynchronous mobile communication system.

In order to enable soft combine, there is a restriction that input data block information, encoding related parameter information, and the like must be identical in the encoding process. That is, in the current asynchronous system, it is very difficult to match these coded transmission symbols in the form of data processing in which each logical channel information is multiplexed by the MAC layer and transmitted to the transport channel. Of course, a number of additional parameter adjustments to the higher layers can make this possible, but can reduce the complexity of the process and the performance of the system.

Accordingly, in order to solve this problem, the present invention proposes a method of applying a soft combine by reprocessing a received symbol at a receiving side, thereby re-encoding a soft combine for a transport block in which a CRC error occurs in the physical layer. Then, the coded data symbols are stored in a buffer and then combined with the data symbols that have been retransmitted. This solves the problem of inconsistency in the coding offset that occurs on the soft combine.

1 is a conceptual diagram illustrating a process in which user data is composed of transport blocks and mapped to a physical channel for transmission;

2 is a block diagram of a soft combine application apparatus using physical layer recoding in an asynchronous mobile communication system according to an embodiment of the present invention;

3 is a block diagram of an existing receiving apparatus,

4 is a flowchart illustrating a soft combine application method using physical layer recoding in an asynchronous mobile communication system according to an embodiment of the present invention.

※ Explanation of code for main part of drawing

110: RLC layer 120: MAC layer

130: physical layer 210: demultiplexer

220: rate matching unit 230: channel decoding unit

240: transport block recovery unit 250; Error detector

260: reverse recombination unit 270: channel encoding unit

280: buffer 290: soft combine unit

In order to achieve the above object, a soft combine application method using physical layer recoding in an asynchronous mobile communication system according to the present invention is a hybrid ARQ (hereinafter referred to as HARQ) type II / in an asynchronous mobile communication system. A method of receiving and processing data by applying III, the method comprising: recovering a transport block through recombination by rate matching, channel decoding, segmentation / combination of received data symbols, and performing error checking on the recovered transport block; First step; A second step of performing inverse segmentation / channel encoding by segmentation / combining and storing the transport block in which an error is detected; And recovering the transport block through rate matching, channel decoding, segmentation / combination of the re-received data symbols, and performing reverse recombination and channel encoding by segmentation / combination on the recovered transport block to perform the stored transmission. And a third step of performing a soft combine with the block, wherein the inverse recombination and channel encoding process is performed only when the coding start point offset of the corresponding transport block is not an initial value.

In order to achieve the above object, a soft combine application apparatus using physical layer recoding in an asynchronous mobile communication system according to the present invention is a hybrid ARQ (hereinafter referred to as HARQ) type II / in an asynchronous mobile communication system. An apparatus for receiving and processing data by applying III, comprising: demultiplexing means for demultiplexing a received data symbol for each channel; Rate matching means for performing rate matching on the demultiplexed data symbols for each channel; Decoding means for channel decoding the rate matched data symbols; Recovery means for performing recombination by segmentation / combination on the decoded data to restore the transport block; Error detecting means for detecting an error of the recovered transport block; Inverse recombination means for performing inverse segmentation by segmentation / combining on the error-detected corresponding block and retransmission block; Encoding means for performing channel encoding on the de-recombined transport block; Storage means for storing the encoded transport block with its sequence number; And soft combine means for retransmitting the stored transport block and performing a soft combine with the inverse recombination and channel encoded retransmission block and then providing the input to the decoding means.

Hereinafter, a soft combine application method and apparatus using physical layer recoding in an asynchronous mobile communication system according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Error recovery for data transport blocks in HARQ type II / III uses an ARQ based retransmission mechanism in the Radio Link Control (RLC) layer. In addition, the physical layer on the receiving side performs a soft combine to reduce the error probability for the channel coded symbols. That is, the physical layer at the receiving side decodes the data transport block based on the additional information and checks the CRC for the transport block to check whether there is an error. If an error exists, the MAC layer is notified of the fact, and the additional information and coded symbol level information of the transport block in which the error occurs are stored in a buffer of the physical layer. After a certain time, the retransmission mechanism in the RLC layer is activated, and the sender retransmits a previously failed transport block.

The physical layer on the receiving side decodes the received data and checks whether there is an error for the corresponding transport block. In this case, when an error is detected again, when symbol level information and a received symbol level information of a transport block previously stored in a buffer have the same RLC sequence number as additional information, a more reliable symbol level information is obtained by combining these information. We then perform a soft combine that reduces the probability of error by creating a, then performing error checking on it.

HARQ in W-CDMA system does not change the actual channel coding rate in the physical layer in order to minimize the impact on the existing system, and adjusts the amount of puncturing in the rate mapping process to adjust the amount of transmission on the physical channel. Use the same method to change the normal channel coding rate. Therefore, the coding rate in the hybrid ARQ indicates the degree of punching, and the higher the coding rate, the lower the ability to adapt to channel error. Additional information transmitted in the form of a parameter to the transmitting physical layer includes an HARQ application indicator, a sequence number of a retransmission RLC PDU, a redundancy version (number of retransmissions of the RLC PDU), and the like. Assuming that the coding rates available in the physical layer are 1, 2/3, 1/2, and 1/3, if the redundancy version of the RLC PDU for the transport block (number of retransmissions of the RLC PDU) is 0, the transmission efficiency is The highest 1 is used, and as the redundancy version value is increased, the coding rate is changed in the order of 2/3, 1/2, 1/3. In the case of a transport block including additional information, 1/3 coding having the lowest coding efficiency is always applied to prevent a case in which transmission blocks including data cannot be decoded due to an error of the additional information.

The physical layer of the transmitting side receives an RLC sequence number and additional information about data to be transmitted from the RLC layer in the form of a parameter. These parameters are passed to the receiver as side information for HARQ, so that the receiver is used to associate the retransmission data with the initial transmission data. That is, when the RLC sequence numbers of newly received data blocks coincide with the RLC sequence numbers of previously received error data blocks, they are combined with each other to perform soft combine.

However, in order to soft combine the data transmission block in which an error occurs, coding should be performed in the form of the same data transmission block as the initial transmission in the retransmission process. Should match.

FIG. 1 is a conceptual diagram illustrating a process in which user data is composed of transport blocks and mapped to a physical channel for transmission.

In the same figure, when two RLC PDUs are delivered to the MAC 120 from the RLC AM entity 1 111 of the RLC layer 110 within the same transmission time interval (TTI), the MAC layer 120 transmits them to the physical layer 130. ). The physical layer 130 configures each RLC PDU into one transport block (TB), and adds a CRC for each.

Subsequently, concatenation and segmentation are performed in an appropriate size to make a coding block unit for encoding. In this case, as shown in the figure, the transport block TB1 is segmented into portions of the coding block units TrB1 and TrB2, the transport block TB2 is segmented into the remaining portions of the coding block unit TrB2 and TrB3, and similarly, the transport block TB3 is represented by the coding block unit TrB4. And TrB5 are divided into two, and it can be seen that there are cases where two transport blocks are combined and connected in one coding block unit. That is, it can be seen that TrB2 includes a part of TB1 and a part of TB2.

Thereafter, the data is transmitted to the receiver through a channel mapping process, which receives the data and decodes the data as opposed to the transmission. At this time, when an error occurs in the received transport block TB2, the coding blocks TrB2 and TrB3 including the data of TB2 should be stored in a state before decoding.

Then, when retransmission is performed on the RLC PDU2, in order to perform soft combine on the retransmission data transmission block, the information of the RLC PDU1 included in the previously transmitted coding block TrB2 must also be coded.

In this case, in order to apply the soft combine for retransmission, data coding of a transport block and information about a coding start point offset for the transport block must be maintained and transmitted to a receiver for a coding block including two or more transport blocks. In this case, the amount of additional information shows a sharp increase.

In order to solve this problem, the present invention performs re-encoding of the data symbols received at the receiving side, so as to adjust the offset for the coding start point of the transport block required for soft combine. This method can perform a soft combine without requiring additional information, which will be described in detail with reference to FIGS. 2 to 4.

FIG. 2 is a block diagram of a soft combine application apparatus using physical layer recoding in an asynchronous mobile communication system according to an embodiment of the present invention.

2, a demultiplexing unit 210 for demultiplexing a received data symbol block by channels (TrCH # 1 to TrCH #n); A rate matching unit 220 for matching data rates with respect to data symbol blocks demultiplexed by channels by the demultiplexer 210; A decoder (Channel Decoding) 230 for channel decoding the rate-matched data symbol block through the rate matching unit 220; A recovery unit 240 for performing recovery by segmentation / combining on the data decoded by the decoding unit 230 and restoring the transport block into a transport block; An error detection unit (CRC check) 250 for detecting an error by checking a CRC of the transport block recovered by the recovery unit 240; An inverse recombination unit 260 for performing inverse recombination by segmentation / combining the corresponding block and the retransmission block detected by the error detection unit 250; An encoding unit (CHannel encoding) 270 for performing channel encoding on the inversely recombined transport block through the inverse recombination unit 260; A buffer 280 for storing the transport block encoded by the channel encoding unit 270 with the sequence number; And a soft combiner 290 which is retransmitted with the transport block stored in the buffer 280 to perform soft combine with the inverse recombination and channel encoded retransmission block and then provides the input to the decoding unit 230. have.

In the conventional receiving apparatus as shown in FIG. 3 compared with FIG. 2, the received symbols punctured by the rate matching unit 220 are recovered for HARQ, and the buffer 280 for HARQ, such as an RLC sequence number, is recovered. Copy it to and save it. These data symbols are recovered into a data bit string by performing channel decoding on the channel decoding unit 230 and combined into data transmission blocks through the recovery unit 240. The error detection unit 250 performs a CRC check for checking whether there is an error for each transport block, and notifies only the fact of error to the upper layer for the transport blocks in which an error is found.

If there is no error in the transport block, the transport block TB is transmitted to the upper layer, and the related transmission data symbols stored in the HARQ buffer 280 are deleted. The transmission side symbols are received by the receiving physical layer again after a predetermined time by a higher layer retransmission procedure for the transmission symbol having an error, and after the rate matching in the rate matching unit 220, the soft combiner 290 Performs a soft combine with the previous data transmission block having the same RLC sequence number stored in the HARQ buffer 280.

However, for the soft combine, the previously received data symbol and the retransmitted data symbol should be the same. For this purpose, the content of the transmitted data and the offset information applied to the coding should be the same. In other words, the same data and coding offset as in the previous transmission should be applied in transmitting a transport block at the transmitting side. Adjusting this causes various problems.

Accordingly, in the present invention, as shown in FIG. 2, an inverse recombination unit 260 and a channel encoding unit 270 are provided in addition to the configuration of FIG. In the reverse recombination unit 260, the output block of the error detection unit 250 is recombined, and then re-encoded by the channel encoder 270 to match a coding offset. This approach has the advantage of enabling soft combines without the addition of additional hardware equipment.

That is, in the present invention, when the physical layer on the receiving side receives the transmission symbols, the rate matching unit 220 performs rate matching and performs channel decoding through the channel decoding unit 230 and the recovery unit 240. The transport block is recovered through recombination of the bit string, and the error detection unit 250 checks the CRC error.

In the case of no error in the present invention of Fig. 2 is the same as the existing method. If there is an error, the inverse recombination unit 260 performs segment encoding / concatenation for each transport block, and then performs channel encoding in the same manner as when transmitting in the channel encoding unit 270, and then encodes the encoded block. Transmission symbols are stored in the HARQ buffer 280 together with additional information.

In this case, when the received transport block is the first transport block within the transmission time interval of each transport channel, it is necessary to perform a separate reverse recombination and encoding process through the reverse recombination unit 260 and the channel encoding unit 270. There is no, and the previously received transmission symbol is stored as it is. That is, the information stored in the HARQ buffer 280 is set so that the starting point coding offset of the transport block is in an initial state, and coded symbols are stored.

Subsequently, when a retransmission of an error transmission symbol is made from the transmitting side and the receiving side receives it, the soft combiner 280 performs a soft combine. If a transmission block in which the received data symbols match the RLC sequence number exists in the HARQ buffer 280, the soft combine is performed if the starting point coding offset of the received transmission data symbol is equal to the initial offset. Next, decoding and recombination of the transmission data symbols currently received through the channel decoding unit 230 and the recovery unit 240 are performed, and the inverse recombination unit 260 and the channel encoding unit 270 are again performed. After recombination, the coding start point offset is initialized and recoded, and then soft combine with the previous received data block in the HARQ buffer 280 is performed.

In this case, the problem of spreading bit errors due to recoding in the channel encoding unit 270 may be substantially adjusted by adjusting the priority in the soft combine process.

FIG. 4 is a flowchart of a method for applying soft combine using physical layer recoding in an asynchronous mobile communication system according to an embodiment of the present invention, and is applied to the receiving device of the present invention as shown in FIG. 2.

First, the receiver receives the transmission data symbols (S401), recovers the transmission block through decoding and mitt manufacture of the received data symbols (S402), and then performs CRC check on the recovered transmission block. (S403).

Then, it is determined whether a CRC error exists (S404), and if there is an error, it is determined whether the RLC sequence number previously matched with the data symbol previously stored in the HARQ buffer is determined (S405). The encoding is performed, and the resultant value is stored in the HARQ buffer together with additional information, and then re-run from step S401 (S406).

If the determination result of step S405 is identical, the transmitter determines whether the coding start point offset of the retransmitted transmission data symbol is an initial value (S407), and if it is not the initial value, reverse recombination and re-encoding of the corresponding transport block are performed (S407). S408).

As a result of the determination of step S407 or after performing step S408, after performing soft combine on the contents of the HARQ buffer and the received transmission data symbol (S409), decoding and segmentation / combination are performed to the transmission block. It recovers and performs a CRC check on the corresponding transport block (S410), it is determined whether the CRC error (S411).

If it is determined that there is no error as a result of the determination of step S404 and step S411, the corresponding transport block is transmitted to a higher layer (S412), and the same content, i.e., the forwarded transport block is deleted from the HARQ buffer, from step S401. If there is an error as a result of the determination of step S411, the content of the HARQ buffer is updated and stored to a current value and then re-run from step S401.

The processing procedure of the embodiment of FIG. 4 shows all the processing procedures in the HARQ type III. In the case of the HARQ type II, since there is no self decoding function, the functional blocks associated with the processing are not performed.

To summarize the technical features of the present invention, the recombination process is performed so that the soft combine at the receiving physical layer can have the same coding offset for the required data transmission blocks, and the transport block in recoding. Recoding should be performed only when the coding start point offset of is not the initial value. Also, soft coding is performed after the recoding is omitted only when the coding start contact offset for the received data transport block is the initial value.

As described in detail above, the method and apparatus for applying soft combine using physical layer recoding in an asynchronous mobile communication system according to the present invention re-encode for soft combine for a transport block in which a CRC error occurs in the physical layer. By storing the coded data symbols in the buffer and combining them with the data symbols that have been retransmitted, the data offset efficiency caused by the soft combine solves the problem of improving data transmission efficiency. .

Claims (3)

A method for receiving and processing data by applying hybrid ARQ type II / III in an asynchronous mobile communication system, A first step of recovering a transport block through recombination by rate matching, channel decoding, segmentation / combination of received data symbols, and performing error checking on the recovered transport block; A second step of performing inverse segmentation / channel encoding by segmentation / combining and storing the transport block in which an error is detected; And The transport block is recovered through rate matching, channel decoding, and segmentation / recombination of re-received data symbols, and segmentation / combination inverse recombination and channel encoding are performed on the recovered transport block. And a third step of performing a soft combine. 4. The method of claim 1, further comprising: a physical layer recoding in an asynchronous mobile communication system. The method of claim 1, The inverse recombination and channel encoding process is performed only when the coding start point offset of the corresponding transport block is not an initial value. An apparatus for receiving and processing data by applying hybrid ARQ type II / III in an asynchronous mobile communication system, Demultiplexing means for demultiplexing the received data symbols on a channel-by-channel basis; Rate matching means for performing rate matching on the demultiplexed data symbols for each channel; Decoding means for channel decoding the rate matched data symbols; Recovery means for performing recombination by segmentation / combination on the decoded data to restore the transport block; Error detecting means for detecting an error of the recovered transport block; Inverse recombination means for performing inverse segmentation by segmentation / combining on the error-detected corresponding block and retransmission block; Encoding means for performing channel encoding on the de-recombined transport block, Storage means for storing the encoded transport block with its sequence number; And And a soft combine means for retransmitting the stored transport block and performing soft combine with the inverse recombination and channel-encoded retransmission block and providing the input to the decoding means. Soft combine application device using layer recoding.