JP2010056845A - Transmitter and receiver using tail-biting convolutional code system, and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a receiver capable of shortening the decoding processing time of tail-biting convolutional coded data and reducing a power consumption. <P>SOLUTION: The receiver characteristically includes: a receiving part (201) which receives rearranged bit strings sequentially rearranged from the head bit of each of a plurality of coded bit strings generated by performing tail-biting convolutional coding of a bit string to which error inspection information is added from a transmitter; a decoding part (204) which performs tail-biting convolutional decoding to the received bit strings; and an error inspection checking part (205) which performs an error inspection by the error inspection information of the decoded bit strings. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless communication system, and more particularly, to a transmission device, a reception device, and their communication control methods using a tail-biting (tail-biting) convolutional coding scheme.

  In LTE (Long Term Evolution), which is being standardized in 3rd Generation Partnership Project (3GPP) Release 8, a tail-biting convolutional coding scheme is used for PBCH (Physical Broadcast Channel) (Non-patent Document 1).

  In 3GPP LTE, a multi-antenna transmission or MIMO (Multiple Input Multiple Output) system is considered to be a technique necessary for improving performance. When multi-antenna transmission is performed, the mobile station trying to connect to the base station has an unknown antenna configuration at the time of decoding the PBCH after the initial synchronization. Furthermore, the TTI of the PBCH is 40 ms, but it is unknown at that time where the current frame (10 ms) is located in 40 ms.

  For example, a mobile station that attempts to decode PBCH after initial synchronization has three possible antenna configurations (here, the number of antennas = 1, 2, or 4), and there are four frames in terms of frame position. A position exists as a possibility. That is, in the initial synchronization, there are 3 × 4 = 12 possibilities regarding the antenna configuration and the frame position in the PBCH configuration, and the mobile station needs to try PBCH decoding up to 12 times.

3GPP TS 36.212 v8.3.0 (2008-05) 5.1.1 to 5.1.5

  However, channel equalization and transmit diversity decoding must be performed each time the possible number of antennas is tried, and as described above, repeating tail-biting convolutional decoding up to 12 times is a PBCH decoding. The processing time is increased, and the power consumption is increased. For mobile stations where low power consumption is always an issue, increasing power consumption is a major problem.

  Accordingly, an object of the present invention is to provide a new communication control method capable of shortening the decoding processing time of tail-biting convolutionally encoded data and reducing power consumption, a transmission device and a reception device, and a wireless communication system using the same. It is to provide.

  A receiving apparatus according to the present invention is a receiving apparatus using a tail-biting convolutional coding scheme, and includes a plurality of encoded bit sequences generated by tail-biting convolutional coding of a bit sequence to which error check information is added. An error is detected by receiving means for receiving the rearranged bit sequence rearranged in order from each head bit from the transmission device, decoding means for tail-biting convolutional decoding of the received bit sequence, and error check information of the decoded bit sequence. Error checking and confirming means for performing inspection.

  A transmission apparatus according to the present invention is a transmission apparatus using a tail-biting convolutional coding scheme, which generates a plurality of encoded bit sequences by tail-biting convolutional coding of an information bit sequence to which error check information is added. Convolutional encoding means, reordering means for generating a rearranged bit sequence that is rearranged in order from the first bit of each of the plurality of encoded bit sequences, and generating and transmitting a transmission signal from the rearranged bit sequence And transmitting means.

  According to the present invention, it is possible to reduce the decoding processing time and power consumption of tail-biting convolutionally encoded data.

  The present invention utilizes the characteristics of the tail-biting convolutional code, that is, the initial state and the final state of the encoder are the same, so that decoding can be started from an arbitrary place at the time of decoding. Remap tail-biting convolutionally encoded bit sequence. On the reception side, tail-biting convolutional decoding is performed on the remapped bit string to reduce the number of tail-biting convolutional decoding, thereby reducing processing time and power consumption.

  Hereinafter, in order not to complicate the description, a 3GPP LTE system in which the number of antennas is 4 will be described as a wireless communication system according to an embodiment of the present invention. However, it is obvious that the present invention can be applied to other systems.

1. System Configuration FIG. 1 is a diagram schematically illustrating a general configuration of a mobile communication system, and FIG. 2 is a resource configuration diagram schematically illustrating a part of subframe # 0 in one frame of a 3GPP LTE system. . Here, as shown in FIG. 1, it is assumed that a mobile station UE (User Equipment) is located in a cell of the base station eNB, and the mobile station UE receives a broadcast channel from the base station eNB.

  As shown in FIG. 2, PBCH is mapped to 4 symbols from the beginning of slot 1 of subframe # 0 consisting of 2 slots. The resource to which the reference signal RS (Reference signal) is mapped is always arranged with reference signals RS for four antennas (antennas 1 to 4) independently of the number of antennas actually used, and PBCH Is not mapped.

  As a procedure for initial synchronization, the mobile station UE first establishes frame synchronization by receiving a synchronization channel (Sync CH), and acquires broadcast information such as cell-specific information on the PBCH after the frame synchronization is established. Hereinafter, configurations of the transmission device (here, the base station eNB) and the reception device (here, the mobile station UE) will be described.

  FIG. 3A is a block diagram illustrating a schematic functional configuration of the transmission device of the wireless communication system according to the present embodiment, and FIG. 3B is a block diagram illustrating a schematic functional configuration of the reception device.

  In FIG. 3A, the transmission apparatus functionally has the following blocks: CRC (Cyclic Redundancy Check) adding unit 101; tail-biting convolutional coding unit 102; interleaving unit 103; remapping unit 104; rate matching unit 105; Block division unit 106; and transmission unit 107. However, these are functionally divided blocks, and similar functions can be realized by executing a program on a program control processor.

  In FIG. 3B, the receiving apparatus functionally has the following blocks: receiving unit 201; rate dematching unit 202; deinterleaving unit 203; tail-biting convolutional decoding unit 204; CRC checking unit 205; and decoding control Part 206. However, these blocks are also functionally divided, and similar functions can be realized by executing a program on the program control processor. As will be described later, the decoding control unit 206 changes the CRC confirmation position according to the confirmation result of the CRC confirmation unit 205 while setting the number of antennas for the reception unit 201.

2. Transmission Operation Hereinafter, the transmission operation of the transmission device will be described in detail with reference to FIG. 3 (A) and FIG.

  FIG. 4 is a schematic diagram illustrating an example of a transmission process of the transmission apparatus illustrated in FIG. First, CRC adding section 101 calculates CRC information, which is error check information, from information 301 (in this case, broadcast information) and adds it to the tail of information 301 to generate CRC added bit sequence 302. The tail-biting convolutional coding unit 102 performs tail-biting convolutional coding with a coding rate of 1/3 on the CRC additional bit sequence 302, and a systematic bit sequence (Systematic bits) having the same sequence length and two parity bits. An encoded bit sequence 303 including a bit sequence (Parity1 bits, Parity2 bits) is generated.

  Subsequently, the interleaving unit 103 interleaves each of the systematic bit sequence (Systematic bits), the parity bit sequence (Parity1 bits), and the parity bit sequence (Parity2 bits) of the coded bit sequence 303 to obtain an interleaved coded bit sequence. 304 is output to the remapping unit 104.

  The remapping unit 104 rearranges the systematic bit sequence (Systematic bits), the parity bit sequence (Parity1 bits), and the parity bit sequence (Parity2 bits) sequentially in the order of S, P1, and P2, one bit at a time. A remapping coded bit sequence 305 is generated.

  The rate matching unit 105 receives the remapping coded bit sequence 305, performs rate matching (repetition) so as to match the 960 bits of the physical channel, and generates a transmission bit sequence 306.

  In order to transmit the rate-matched transmission bit sequence 306 in 40 ms, the block dividing unit 106 divides it into data blocks every 10 ms, and sequentially outputs them to the transmitting unit 107. Here, the data length divided into four is always a multiple of 3, and the head of each data block always starts with S (Systematic bit).

  The transmission unit 107 performs QPSK modulation on the data block and transmits the data block using a BPCH resource as a broadcast signal (see FIG. 2).

3. Reception Operation Hereinafter, reception control of the reception apparatus will be described in detail with reference to FIG. 3B and FIGS.

  FIG. 5 is a flowchart showing the overall reception process of the receiving apparatus shown in FIG. 3B, and FIGS. 6A to 6C are flowcharts showing channel processing according to the number of antennas.

  First, under the control of the decoding control unit 206, the receiving unit 201 sets the first antenna configuration candidate (number of antennas = 1) and executes channel processing (step 401), and further demodulates the received signal (here, QPSK demodulation). ) Is executed (step 402). In channel processing with the number of antennas = 1 (step 401), the receiving unit 201 sets the number of antennas to 1 (step 501), as shown in FIG. 6A, and performs channel estimation and channel equalization for one antenna. (Steps 502 and 503) are executed.

  Subsequently, the rate dematching unit 202 and the deinterleaving unit 203 perform rate dematching and deinterleaving on the demodulated data, thereby receiving a received bit sequence (having a bit arrangement of the remapping coded bit sequence 305 shown in FIG. Hereinafter, this reference number is referred to as “305 ′”) (step 403). The rate dematching unit 202 adds the data that has been repeated as described above, but the data after the addition always starts with a systematic bit (S).

  The tail-biting convolutional decoding unit 204 receives the received bit sequence 305 ′ and performs tail-biting convolutional decoding to output a reception information bit sequence including a CRC bit sequence to the CRC confirmation unit 205 (step 404). As is well known, in the tail-biting convolutional coding, since the initial state and the final state of the encoder are the same, decoding can be started from an arbitrary place at the time of decoding. Therefore, decoding can be performed even in the middle of the received bit sequence 305 'having the bit arrangement of the remapping encoded bit sequence 305 shown in FIG.

  Subsequently, the CRC confirmation unit 205 performs CRC confirmation from the decoded received information bit sequence (step 405), and determines whether or not the CRC confirmation result is OK (step 406). As described above, it is unknown which data in the current data is within TTI = 40 ms, and the data break is different depending on the data block every 10 ms. Therefore, the CRC is always added to the end of the data. Is not limited. Therefore, the CRC confirmation determination (steps 405 and 406) is repeated while changing the CRC confirmation position a predetermined number of times (four times here) (steps 407 and 408). Hereinafter, an example in which there are four CRC confirmation position candidates (candidates 1 to 4) will be described.

  FIG. 7 is a schematic diagram showing CRC position candidates of data subjected to tail-biting convolutional decoding. As shown in FIG. 7, CRC position candidates 1 to 4 exist in a one-to-one correspondence between data breaks. If the CRC is not OK in step 406 (step 406: NO), if the predetermined number of times has not been reached (step 407: NO), the CRC position candidates are sequentially changed (step 408), and the CRC is confirmed. (Steps 405 and 406). If the CRC confirmation result is OK for a certain CRC confirmation position candidate (step 406: YES), the PBCH determines that the number of currently attempted antennas and the CRC position are correct. In this way, the data block currently being decoded is identified as which data block in 40 ms, and the process is terminated.

  If the CRC determination is not OK in any of the four CRC position candidates 1 to 4 (step 407: YES), the decoding control unit 206 sets the receiving unit 201 as the second antenna configuration candidate (number of antennas = 2). (Step 409: NO, Step 410), Steps 402 to 408 described above are repeated.

  In channel processing with the number of antennas = 2 (step 410), the receiving unit 201 sets the number of antennas to 2 (step 504), as shown in FIG. 6B, and performs channel estimation and channel equalization for two antennas. After executing (Steps 505 and 506), transmit diversity decoding (SFBC) is performed (Step 507).

  Even if the number of antennas = 2, if the CRC determination does not result in OK (step 406: NO, step 407: YES, step 409: YES), the decoding control unit 206 sets the receiving unit 201 as the third antenna configuration candidate (antenna (Number = 4) (step 409: NO, step 410), and steps 402 to 408 described above are repeated.

  In the channel processing with the number of antennas = 4 (step 412), the receiving unit 201 sets the number of antennas to 4 (step 508) and performs channel estimation and channel equalization for four antennas as shown in FIG. 6C. After executing (Steps 509 and 510), transmit diversity decoding (SFBC + FSTD: frequency-shift time diversity) is performed (Step 511).

 Even if the number of antennas = 4, if the CRC determination does not result in OK (step 406: NO, step 407: YES, step 409: YES, step 411: YES), even if decoding for all antenna configurations is attempted, the CRC Since the determination is not OK, the decoding control unit 206 ends the process with no decoding result.

4). Effect As described above, according to an embodiment of the present invention, when it is unknown where the currently decoded frame is located in 40 ms, tail-biting convolutional decoding is performed according to each of the four candidates. There is no need, and it is only necessary to perform decoding three times in total, once for each antenna number candidate. Also. The CRC position detection at 40 ms can be detected by performing CRC confirmation at four candidate positions from the decoded bit string and confirming that the CRC determination is OK.

  Therefore, according to the above-described example, when the present embodiment is not applied, the number of times of tail-biting convolutional decoding is 12 times at maximum, but by applying this embodiment, the number of times is 3 times at maximum. Can be reduced. This makes it possible to shorten the time for PBCH decoding at the time of initial synchronization.

  The present invention can be applied to a mobile communication system, a base station, and a user terminal (mobile station or portable communication terminal) compatible with LTE under consideration in 3GPP Release 8.

It is a figure which shows typically the general structure of a mobile communication system. It is a resource block diagram which shows typically a part of sub-frame # 0 in 1 frame of 3GPP LTE system. (A) is a block diagram showing a schematic functional configuration of the transmission device of the wireless communication system according to the present embodiment, and (B) is a block diagram showing a schematic functional configuration of the reception device. It is a schematic diagram which shows an example of the transmission process of the transmitter shown to FIG. 3 (A). It is a flowchart which shows the whole reception process of the receiver shown in FIG.3 (B). (A)-(C) is a flowchart which shows the channel process according to the number of antennas, respectively. It is a schematic diagram which shows the CRC position candidate of the data by which tail-biting convolution decoding was carried out.

Explanation of symbols

101 CRC adding unit 102 tail-biting convolutional coding unit 103 interleaving unit 104 remapping unit 105 rate matching unit 106 block dividing unit 107 transmitting unit 201 receiving unit 202 rate dematching unit 203 deinterleaving unit 204 tail-biting convolutional decoding unit 205 CRC confirmation unit 206 Decoding control unit

Claims (14)

In a receiver using a tail-biting convolutional coding scheme,
Receiving means for receiving, from the transmitter, a rearranged bit sequence rearranged in order from the first bit of each of a plurality of encoded bit sequences generated by tail-biting convolutional coding of a bit sequence to which error check information is added When,
Decoding means for tail-biting convolutionally decoding the received bit sequence;
Error check confirming means for performing error check based on the error check information of the decoded bit sequence;
A receiving apparatus comprising:   The receiving apparatus according to claim 1, further comprising a control unit that operates the error check confirming unit while sequentially changing position candidates of the error check information in the decoded bit sequence.   The receiving apparatus according to claim 2, wherein the control means further operates the receiving means, the decoding means, and the error check confirming means while sequentially selecting antenna configuration candidates of the transmitting apparatus.   The transmission apparatus is a base station in a mobile communication system, and the receiving means receives the rearranged bit sequence through a broadcast channel from the base station after initial synchronization with the base station. The receiving device according to any one of 1-3. In a transmitter using a tail-biting convolutional coding scheme,
Tail-biting convolutional coding means for generating a plurality of coded bit sequences by tail-biting convolutional coding of an information bit sequence to which error check information is added;
Re-arrangement means for generating a rearranged bit sequence rearranged in order from the first bit of each of the plurality of encoded bit sequences;
Transmitting means for generating and transmitting a transmission signal from the rearranged bit sequence;
A transmission device comprising:   6. The transmission apparatus according to claim 5, wherein the transmission unit transmits the rearranged bit sequence through a broadcast channel. In a wireless communication system that performs wireless communication between a transmission device and a reception device,
The transmitter is
Tail-biting convolutional coding means for generating a plurality of coded bit sequences by tail-biting convolutional coding of an information bit sequence to which error check information is added;
Re-arrangement means for generating a rearranged bit sequence rearranged in order from the first bit of each of the plurality of encoded bit sequences;
Transmission means for generating and transmitting a transmission signal from the rearranged bit sequence, and
The receiving device is:
Receiving means for receiving a received bit sequence from the transmitting device in which initial synchronization is established;
Decoding means for performing tail-biting convolutional decoding of the received bit sequence;
Error check confirmation means for performing error check based on the error check information of the decoded bit sequence;
A wireless communication system comprising: A communication control method in a receiving apparatus using a tail-biting convolutional coding method,
a) receiving a rearranged bit sequence rearranged in order from the first bit of each of a plurality of encoded bit sequences generated by tail-biting convolutional coding of the bit sequence to which error check information is added;
b) tail-biting convolutionally decoding the received bit sequence;
c) Perform error check confirmation based on the error check information of the decoded bit sequence.
A communication control method characterized by the above.   9. The communication control method according to claim 8, wherein, in c), the error check is confirmed while sequentially changing the position candidates of the error check information in the decoded bit sequence.   10. The communication control method according to claim 8, wherein the a) to c) are repeated while sequentially selecting antenna configuration candidates for the transmission apparatus. A communication control method in a transmission device using a tail-biting convolutional coding method,
a) tail-biting convolutional coding of the information bit sequence with the error check information added to generate a plurality of encoded bit sequences,
b) generating a rearranged bit sequence rearranged in order from the first bit of each of the plurality of encoded bit sequences;
c) generating and transmitting a transmission signal from the rearranged bit sequence;
A communication control method characterized by the above. A communication control method in a wireless communication system for performing wireless communication between a transmitting device and a receiving device,
The transmitter is
a) tail-biting convolutional coding of the information bit sequence with the error check information added to generate a plurality of encoded bit sequences,
b) generating a rearranged bit sequence rearranged in order from the first bit of each of the plurality of encoded bit sequences;
c) generating and transmitting a transmission signal from the rearranged bit sequence;
The receiving device is:
d) receiving a received bit sequence from the transmitting device in which initial synchronization is established;
e) tail-biting convolutionally decoding the received bit sequence,
f) Perform error check confirmation based on the error check information of the decoded bit sequence.
A communication control method in a wireless communication system. A program for realizing a communication control function in a program control processor of a receiving apparatus using a tail-biting convolutional coding method,
a) receiving a rearranged bit sequence rearranged in order from the first bit of each of a plurality of encoded bit sequences generated by tail-biting convolutional coding of the bit sequence to which the error check information is added;
b) tail-biting convolutionally decoding the received bit sequence;
c) performing error check confirmation with error check information of the decoded bit sequence;
A program for realizing a communication control function. A program for realizing a communication control function in a program control processor of a transmission device using a tail-biting convolutional coding method,
a) tail-biting convolutionally encoding an information bit sequence to which error check information is added to generate a plurality of encoded bit sequences;
b) generating a rearranged bit sequence that is rearranged in order from the first bit of each of the plurality of encoded bit sequences;
c) generating and transmitting a transmission signal from the rearranged bit sequence;
A program for realizing a communication control function.

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