KR100720539B1 - Rate Matching Method and Apparatus - Google Patents

Abstract

The present invention relates to next generation mobile communication, and more particularly, to a data rate matching method of next generation mobile communication in which symbol repetition and symbol puncturing are mutually exclusive on one transmission chain. In the present invention, in the process of interleaving an information bit string having no normal data rate to be mapped to a physical layer, the channel-coded information bit string is exclusive by either symbol repetition or symbol puncturing according to a desired length of an interleaver. Is performed to match the desired interleaver length. Accordingly, the present invention has the effect of ensuring the operation of the multi-variable data rate and the variable data rate on all radio structures in the 3GPP2 standard by using a uniform puncturing algorithm in the existing chain, due to the operation of the uniform puncturing algorithm In some wireless architectures, it is possible to increase the maximum information data rate for multivariate data rates.

Variable data rate, multivariate data rate, transmission chain

Description

Rate Matching Method and Apparatus

1 illustrates a radio architecture (RC) in the forward link to support variable and multivariate data rates according to the prior art;

The present invention relates to next generation mobile communication, and more particularly, to a data rate matching method of next generation mobile communication in which symbol repetition and symbol puncturing are mutually exclusive on one transmission chain.

In general, in addition to the normal data rate mode, there are two transmission modes in the data transmission mode of the next generation mobile communication (hereinafter, referred to as 3GPP2), a variable data rate mode and a multivariate data rate mode.

The normal data rate mode refers to a transmission mode that operates on a fixed chain called a radio configuration (hereinafter referred to as RC).

RC can be thought of as a type of transmission chain formed by matching the length of the information data, the length of the channel interleaver, and the length of the output string of the channel encoder according to the code rate of the channel code. At this time, there is a formal rule between the length of the channel interleaver, the coding rate of the channel encoder, and the length of the Walsh code of the channel.

In other words, when the chip rate to be used is determined, the number of chips into one modulation symbol is determined according to the length of the channel interleaver, which can be defined as a spreading factor. The length of the Walsh code that can code multiplex the channels is determined.

At this time, the number of available Walsh codes is in proportion to the length of the Walsh code. Accordingly, the number of channels that can be accommodated in the multiplexing chain varies according to the Walsh code.

Consider the length after channel coding for input information bits having the same length. In this case, the ability of an error correction code to correct an error that may occur in a channel is stronger as the coding rate of the channel encoder is lower.

In other words, the lower the coding rate of the channel encoder is, the better the error correction capability is, and thus the lower the transmission power can be used. However, when a channel coder having a low code rate is used, the length of the output string of the channel encoder is increased, thereby increasing the length of the channel interleaver.

This results in an increase in the modulation symbol rate, thereby reducing the number of chips in one modulation symbol at a fixed chip rate.

This results in a reduction in the number of useful Walsh codes.

On the contrary, if the channel coding technique of high coding rate is used for the input string of the same length channel encoder, the error correction capability is reduced but the length of the output string of the channel encoder is shortened. Length of channel interleaver may be used, resulting in an increase in the number of Walsh codes that may be useful.

As described herein, it can be seen that there is a trade-off relationship between the coding rate of the channel encoder and the Walsh code space. Considering this trade-off relationship, RC can be thought of as a formalization of a transmission chain that can be used to secure Walsh code space, or a transmission chain that can be used when lower transmission power is required. .

Currently, 3GPP2 defines several RCs for 1X systems using a chip rate of 1.2888Mcps and some formal RCs for 3X systems using a chip rate of 3.6864Mcps.

One thing to note here is that the spreading factor has an exponential value of 2, so that the input data rate and the length of the interleaver defined in each RC are also increased by twice.

Before the traffic channel is established between the terminal and the base station, the terminal and the base station determine the RC to be used through the negotiation process and the spreading factor on each RC, that is, the length of the channel interleaver, and the communication process proceeds according to the chain.

The modes of using a transmission chain other than the transmission chain defined on the RC are the variable data rate mode and the multivariate data rate mode.

Variable data rate mode is a transmission method that can support any data rate in addition to the standard data rate supported by each RC. This variable data rate was introduced to support Adaptive Multi-Rate (hereinafter abbreviated as AMR) codec, which is one of the 3GPP speech codecs on the physical layer of 3GPP2.

That is, in the case of AMR, data bits that do not match the standard data rate supported by each RC of 3GPP2 can be dropped during the frame period for 20ms.

Next, there is what is called a multivariate data rate mode. The purpose of this mode is to:

In the 3GPP2 system, the base station schedules transmission on the forward auxiliary channel. At this time, the base station allocates a fixed data rate to the terminal through a message.

However, the channel situation between the base station and the specific terminal may change during that particular time, and the system load of the base station may also change.

For example, as the terminal moves away from the base station, the situation of the channel may change, and the channel environment may deteriorate, and thus, the base station may not have sufficient transmit power for transmitting at a current data rate to a specific terminal.

To solve this problem, the base station may stop transmitting to the auxiliary channel during this time. This solution, however, causes delays in data transmission and can also cause unnecessary waste of useful transmission power and Walsh codes.

Another solution is to consider how the base station reschedules the transmission data rate after a certain amount of time. However, this also causes problems such as time delay and waste of Walsh code.

This situation is not unique to the forward link. Likewise, in the reverse link, the channel state between the terminal and the base station may change according to the movement of the terminal, and thus, there may be a lack of transmission power to maintain proper quality.

Thus, a mode called multivariate data rate has been used to solve this situation. In this mode, the transmission rate is changed in units of frames depending on the situation. That is, when it is determined that the channel environment is deteriorated, the base station lowers the transmission rate of the auxiliary channel. If it is determined that the channel environment is recovered again, it can be considered that the transmission mode is performed again at the previous transmission rate. Using this multivariate data rate mode, the base station can use the power available at the base station without frequent rescheduling.                         

In order to support the variable data rate mode and the variable data rate mode, each RC of 3GPP2 currently configures a transmission chain using the following method.

As described above, the length of the channel interleaver used in each RC is determined according to the spreading factor. At this time, since the spreading factor has a value increasing in the form of an exponential power of 2, the length of the interleaver determined for a certain spreading factor and the length of the interleaver determined for the spreading factor one step lower than that is exactly 1: 2. Will have a relationship with

In this case, let the large spreading factor A be the small spreading factor B. Then, in each RC, a 1: 1 mapping relationship is established between the spreading factor and the information bit string input to the channel encoder. If the length of the information bit string input to the channel encoder for the spreading factor A is I _A , and the length of the information bit string input to the channel encoder for the spreading factor B is I _B , then I _B = 2 * I _A Will have a relationship with Also, if the length of each channel interleaver to be used is N _A and N _B , there will be a relationship of N _B = 2 * N _A.

In this case, consider a variable data rate mode in which I satisfying a relationship of "I _A <I <I _B " rather than the length of data to be normalized becomes the length of an input string of a channel encoder.

Assuming that the coding rate of the channel incubator used in the current RC is 1 / n, the output of "n * I" will be sent for the input of I.

At this time, the relationship of "N _A <n * I <N _B " is satisfied. Therefore, some work is required to match the length "n * I" of the output string of the channel encoder to the interleaver length.

The current approach taken by 3GPP2 is to match the length L (= n * I) of the output string of the channel encoder to the interleaver of N = N _B. Accordingly, bit repetition of "N _B -n * I" is performed. The method of doing this performs a uniform iteration process of the following form.

번째 입력 비트열의 코드 심볼로부터 추정 가능하다.That is, the kth output symbol of the iteration block is for index k that increases from 0 to N-1.

It can be estimated from the code symbols of the first input bit string.

Next, a method for supporting the multivariate data rate mode will be described.

In multivariate data rate mode, the maximum data rate, one level lower data rate, and two levels lower data rate that can be supported during the initial negotiation process are defined as a set of transmission data rates.

Therefore, in the multivariate data rate mode for the current auxiliary channel, the data rate of the auxiliary channel is adjusted between the support rate up to two levels below. At this time, if the forward channel is considered, the terminal must determine the rate variation through the blind rate detection. Accordingly, if the data transmission rate is too large, a problem arises that increases the complexity of the terminal.                         

The length of the channel interleaver and the Walsh code used at the maximum data rate should not be changed. In other words, the interleaver and Walsh codes specified for the maximum transmission rate currently used are used as they are.

Therefore, if the data rate is lowered to 1/2 of the maximum rate, the symbol repetition is doubled to match the length of the interleaver to be used in the channel and the length of the output string of the channel encoder.

Similarly, if the data rate is lowered to 1/4 of the maximum data rate, four times symbol repetition is performed to match the length of the interleaver to be used in the channel and the length of the output string of the channel encoder.

The previous example is an example of a variable data rate in the secondary channel of the forward channel.

Multivariate data rate modes for variable data rates may be supported in the secondary channel.

In this case, however, the definitions of the variable data rate and the multivariate data rate mode are blurred. In other words, even if the maximum data rate in the multivariate data rate mode is the normal rate set on the current RC, and the data rate one step lower is the data rate set on the current RC, the data is actually already one step lower. The rate can also be seen as a variable data rate that does not use a chain defined on the current RC. This is because the length of the interleaver, that is, the spreading factor, in the multivariate data rate mode is fixed at that of the maximum transmission rate.

As an example, consider the RC4 of the current forward channel. At this time, a half rate turbo code or a convolution code is used. Assume that the maximum data rate that can be used in the multivariate data rate mode is 76.8 kbps. At this time, the length of the interleaver used in the forward RC4 is fixed to 3072. Consider a multivariate data rate method in this mode. Assume that the available data rate is used at an appropriate value among the set of {19.2 kbps, 38.4 kbps, 76.8 kbps}. The data rates of 38.4 kbps and 19.2 kbps are clearly defined at RC4, but the problem is that there is no chain connecting these rates at 3072, the length of the current interleaver on this RC. As a result, this rate can also be viewed as a variable data rate.

As a result, if the length of the interleaver is fixed to N even in the multivariate data rate mode, and the data rate being transmitted is not defined on the current RC, the output of the channel encoder through the uniform iteration algorithm described above You can match the length of a row to the length of a given interleaver.

When the transmission chain for supporting the variable data rate or the variable data rate is included on an existing regular chain, the basic functional block diagram as shown in FIG. Here, the radio structure 5 in the forward link will be described as an example.

1 is a diagram illustrating a radio structure 5 (RC) of a forward link on a transmission chain according to the prior art.

First, a 0 or 1 spare bit is added to the channel bit (S10), and a CRC bit having an arbitrary length is added to the channel input bit (S11) for error detection.

After the CRC bit is added to the channel input bit, a tail bit or reserved bits are added to this bit string (S12). In this case, 8 tail bits are added when the convolution code is used, and 6 tail bits and 2 reserved bits are added for the turbo code.

The CRC and the spare bits and the tail bits are added to form an information bit string, which is channel coded by a turbo code or a convolutional code (S13), and symbol repetition (S14) to match the desired interleaver length, The symbol puncturing (S15) is made and the block interleaving in the block interleaver (S16).

As can be seen from FIG. 1, symbol repetition is performed after channel coding with a turbo code or a convolutional code on an existing chain, followed by symbol puncturing. Thus, both symbol repetition and symbol puncturing operate on existing normal data rate chains. However, in the operation of the variable data rate and the variable data rate, since the actual rate adaptation is achieved through the uniform repetition process in the symbol repetition block as described above, the symbol puncturing block does not operate.

For example, considering the radio structure 5 on the forward link and the radio structure 4 on the reverse link and considering the multivariate data rate mode, there is a multilateral operation mode that cannot be operated in the current chain.

Information data rate Length of encoder output string Rate matching Desired interleaver length 115.2 kbps 2304 * 4 = 9215 4 bit puncturing among 12 bits (regular chain puncturing) 6144 80 kbps 1600 * 4 = 6400 Operation 6144 57.6 kbps 1152 * 4 = 4608 1536 symbol repetition (multiple symbol repetition) 6144

Table 1 shows the problems of the multivariate data rate mode of operation in radio architecture 5 on the forward link and radio architecture 4 on the reverse link. In Table 1, it is assumed that the virtual set of multivariate data rates is composed of three types of {115.2kbps, 80kbps, 57.6kbps}. The size of the desired channel interleaver for the maximum allocated data rate is then 6144. The chain for the maximum allocated data rate, 115.2kbps, can be thought of as a conventional regular data rate chain, and as shown in Fig. 1, four symbols are punctured among 12 code symbols for rate adaptation. .

In this case, a symbol puncturing pattern for puncturing four symbols out of twelve is defined in the standard for the turbo code and the convolution code as one fixed pattern. Next, the chain for 57.6 kbps can be regarded as a kind of variable chain. In this case, a uniform symbol repetition algorithm of 1536 bits must be performed to fit the length of the output string of the 4608 bit channel encoder to the size of the 6144 bit interleaver. The puncturing block in FIG. 1 is stopped. However, the problem is that the length of the output stream of the channel encoder for 80 kbps in Table 1 is 6400 bits, which is larger than the length of the desired channel interleaver 6144. Therefore, it is impossible to complete the existing regular chain as shown in FIG.

Accordingly, an object of the present invention has been made in view of the above-described problems of the prior art, and provides a data rate matching method for next-generation mobile communication to support variable data rates and multi-variable data rates on an existing transmission chain. will be.

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번째 비트가 되도록 비트 반복을 수행하고, (b) 상기 인코딩된 비트열의 길이가 인터리버 길이보다 큰 경우, 상기 인코딩된 비트열에 대해 펑처링을 수행하되, 상기 펑처링 후의 k 번째 비트가 비트 펑처링 수행 전의 번째 비트가 되도록 펑처링을 수행하는 단계를 포함하여 이루어진다. 여기서, L 은 인코딩 결과 출력된 비트열의 길이, 상기 N 은 인터리버 길이,

는 x 를 넘지않는 최대 정수를 의미한다.
또한, 본 발명은 입력 비트열에 대해, 소정의 코딩 레이트로 인코딩을 수행하는 단계 및 상기 인코딩된 비트열의 길이가 인터리버 길이보다 작은 경우, 상기 인코딩된 비트열에 대해 비트 반복(repetition)을 수행하되, 상기 비트 반복 수행 후의 출력의 k 번째 비트가 상기 인코딩된 입력 비트열의

번째 비트가 되도록 비트 출력을 수행하는 단계를 포함하여 이루어진다. 여기서, 상기 L 은 상기 인코딩된 비트열의 길이, 상기 N 은 인터리버 길이,

는 x 를 넘지 않는 최대 정수를 의미한다.
본 발명은 입력 비트열에 대해, 소정의 코딩 레이트로 인코딩을 수행하는 인코더와, 상기 인코딩된 비트열의 길이가 인터리버 길이보다 작은 경우, 상기 인코딩된 비트열에 대해 비트 반복(repetition)을 수행하되, 상기 비트 반복 수행 후의 출력의 k 번째 비트가 상기 인코딩된 입력 비트열의

번째 비트가 되도록 비트 출력을 수행하고, 상기 인코딩된 비트열의 길이가 인터리버 길이보다 큰 경우, 상기 인코딩된 비트열에 대해 펑처링을 수행하되, 상기 펑처링 후의 출력의 k 번째 비트가 상기 인코딩된 비트열의

번째 비트가 되도록 비트 출력을 수행하는 레이트 매칭기 및 상기 비트 반복 또는 레이트 매칭이 수행된 비트열에 대해 인터리빙을 수행하는 상기 인터리버를 포함하여 이루어진다. 여기서, 상기 L 은 인코딩 결과 출력된 비트열의 길이, 상기 N 은 인터리버 길이,

는 x 를 넘지않는 최대 정수를 의미한다.According to the present invention, a symbol repetition algorithm or a symbol puncturing method for symbol repetition and symbol puncturing is suitable for supporting both a variable data rate and a variable data rate on an existing chain that is performed on one transmission chain. We propose a data rate matching method for next-generation mobile communication that is mutually exclusive on a mobile station.
The present invention performs encoding on an input bit string at a predetermined coding rate and performs any one of bit repetition and puncturing exclusively. (A) When the length of the encoded bit string is smaller than an interleaver length, Bit repetition is performed on the encoded bit string, where the k th bit after the bit repetition is performed before the bit repetition is performed.

Bit repetition is performed so as to be the fourth bit, and (b) when the length of the encoded bit string is larger than the interleaver length, puncturing is performed on the encoded bit string, and the k th bit after the puncturing is bit punctured. ex And performing puncturing to become the first bit. Where L is the length of the bit string output as a result of encoding, N is the length of the interleaver,

Is the maximum integer not exceeding x.
The present invention also provides a method of performing encoding on an input bit string at a predetermined coding rate and performing bit repetition on the encoded bit string when the length of the encoded bit string is smaller than an interleaver length. The k th bit of the output after performing the bit iterations of the encoded input bit stream

And performing a bit output to be the first bit. Where L is the length of the encoded bit string, N is the interleaver length,

Is the maximum integer not exceeding x.
The present invention provides an encoder for encoding an input bit stream at a predetermined coding rate, and when the length of the encoded bit stream is smaller than the interleaver length, performing bit repetition on the encoded bit stream. The k th bit of the output after the iteration is performed on the encoded input bit stream.

Bit output is performed so as to be the first bit, and when the length of the encoded bit string is greater than the interleaver length, puncturing is performed on the encoded bit string, and the k th bit of the output after the puncturing is the encoded bit string.

And an interleaver performing interleaving on the bit string on which the bit repetition or rate matching is performed. Where L is the length of the bit string output as a result of encoding, N is the length of the interleaver,

Is the maximum integer not exceeding x.

First embodiment

In the first embodiment, a symbol repetition algorithm for supporting a variable data rate and a multivariate data rate is proposed.

The symbol repetition algorithm for supporting variable data rate and variable data rate is defined as follows. In this case, the symbol repetition is performed when the length of the channel-coded information bit string is smaller than the length of the desired interleaver. First, the symbol repetition factor is defined as follows.

When the length of the output string of the channel encoder is L and the length of the desired channel interleaver is N, the symbol repetition factor is defined as "N / L". If the calculated symbol repetition factor has a value less than 1, the symbol repetition block is stopped. However, if the symbol repetition factor has a value of 1 or more, uniform symbol repetition is performed by performing the following algorithm.

Uniform symbol iteration algorithm

"번째 심볼로부터 추정 가능하다.The kth output symbol of the symbol repeating block is " out of the input symbols (output string of the channel encoder) of the symbol repeating block.

It can be estimated from the "th symbol.

Where k is a value increasing from 0 to N-1, L is the number of symbols encoded per frame in the encoder output string, N is the length of a desired channel interleaver, and N is greater than or equal to L. Has

When N is smaller than L, the block for performing uniform symbol repetition is stopped, and the block for performing puncturing is operated.

Second embodiment

In the second embodiment, a symbol puncturing algorithm for supporting a variable data rate and a multivariate data rate is proposed.

If the length of the output string of the channel encoder is larger than the length of the desired channel interleaver, puncturing is performed by the following puncturing algorithm.

Uniform symbol puncturing algorithm

"번째 심볼로부터 추정 가능하다.The kth output symbol of the puncturing block is " of the input symbols (output string of the channel encoder) of the puncturing block.

It can be estimated from the "th symbol.

Where k is a value increasing from 0 to N-1, L is the number of symbols encoded per frame in the encoder output string, N is the length of a desired channel interleaver, and N has a smaller value than L. .

If N is greater than or equal to L, the block for performing puncturing is stopped.

One thing to note here is that the operation of the puncturing block and the symbol repetition block are mutually exclusive. That is, the symbol puncturing block is always stopped when the symbol repetition block is performed, and conversely, when the symbol puncturing block is performed, the symbol repetition block is stopped.

One disadvantage of the algorithm in the second embodiment is a problem regarding the optimality of the turbo puncturing algorithm. The above algorithm works best for convolutional codes. However, in the case of turbo code, some loss may occur because it does not satisfy the requirements for basic turbo code puncturing. Therefore, in the second embodiment above, in particular, a separate puncturing algorithm for the turbo code may be defined. That is, an algorithm of a type that excludes puncturing on cystic bits of a turbo code may be defined.                     

When constructing a transmission chain using the puncturing algorithm described above, additional gain can be obtained. That is, it is possible to increase the maximum information data rate for the variable data rate defined in the radio structure. As a result, a radio structure in which the maximum information data rate is increased includes radio structures 4 and 6 of the reverse link, and radio structures 5 and 9 of the forward link. This is summarized in Table 2 below.

Wireless structure Traditional transmission chain Transmission chain according to the invention Number of bits (information + CRC + tail) Information data rate (bps) Number of bits (information + CRC + tail) Information data rate (bps) Reverse radio architecture 4 3072 153600 4607 230350 Reverse radio architecture 6 18432 921600 20735 1036750 Forward wireless architecture 5 3072 153600 4607 230350 Forward wireless architecture 9 18432 921600 20735 1036750

That is, as shown in Table 2, when symbol repetition or symbol puncturing is performed for a flexible data rate, the maximum information rate of the information bit string is relatively high.

As described above, the present invention allows the uniform puncturing algorithm to be used in an existing chain, thereby ensuring the operation of the variable data rate and the variable data rate on all radio structures in the 3GPP2 standard.

In addition, due to the operation of the uniform puncturing algorithm, it is possible to increase the maximum information data rate for multivariate data rates on some radio structures.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

Claims (16)

Performing encoding on the input bit stream at a predetermined coding rate; And Perform either exclusively between bit iteration and puncturing, (a) if the length of the encoded bit string is smaller than the length of the interleaver, bit repetition is performed on the encoded bit string, and the k th bit after the bit repetition is performed before the bit repetition is performed.

Repeat the bit so that it is the first bit, (b) if the length of the encoded bit string is greater than the interleaver length, perform puncturing on the encoded bit string, wherein the k th bit after the puncturing is performed before bit puncturing.

Performing puncturing to become the first bit A rate matching method comprising a (L is the length of the bit string output as a result of the encoding, N is the interleaver length,

Is a maximum integer not exceeding x). The method of claim 1, The length of the input bit string is different from the length of the bit string corresponding to a predetermined radio configuration (RC). The method of claim 2, And a length of the input bit string is determined according to a flexible data rate. Performing encoding on the input bit stream at a predetermined coding rate; And If the length of the encoded bit string is smaller than the length of the interleaver, bit repetition is performed on the encoded bit string, and the k th bit of the output after performing the bit repetition is the length of the encoded input bit string.

Performing a bit output to be the first bit A rate matching method comprising: (L is the length of the encoded bit string, N is the interleaver length,

Is a maximum integer not exceeding x). delete The method of claim 4, wherein The length of the input bit string is different from the length of the bit string corresponding to a predetermined radio configuration (RC). The method of claim 6, And a length of the input bit string has a variable data rate. The method of claim 4, wherein And a length of the input bit string is changed in units of frames. The method of claim 8, And a length of the input bit string has a variable data rate. The method of claim 4, wherein And the encoding scheme is convolutional coding or turbo coding. The method of claim 4, wherein And performing channel interleaving on the output on which the bit repetition is performed. The method of claim 4, wherein And the bit repetition is performed when N / L is greater than one. An encoder for encoding the input bit stream at a predetermined coding rate; If the length of the encoded bit string is smaller than the length of the interleaver, bit repetition is performed on the encoded bit string, and the k th bit of the output after performing the bit repetition is the length of the encoded input bit string.

Outputs the bit to be the first bit, If the length of the encoded bit string is greater than the interleaver length, puncturing is performed on the encoded bit string, wherein a kth bit of the output after the puncturing is the length of the encoded bit string.

A rate matcher for performing a bit output to be the first bit; And The interleaver performing interleaving on the bit string on which the bit repetition or rate matching is performed A rate matching device comprising: (L is the length of the bit string output as a result of the encoding, N is the interleaver length,

Is a maximum integer not exceeding x). The method of claim 13, And the encoder is either a turbo encoder or a convolutional encoder. The method of claim 13, And a length of the input bit string has a variable data rate. The method of claim 13, And a length of the input bit string has a variable data rate.

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