KR100640923B1 - method for encoding TFCI - Google Patents

Abstract

According to the present invention, a transport format combination indicator inserted in each time slot of a radio frame in a mobile communication system using a wideband code division multiple access (hereinafter, referred to as W-CDMA) scheme in the next generation mobile communication. When TFCI is transmitted), the present invention relates to an appropriate TFCI encoding method. For a single physical channel multiplexed through multiple channel coding and rate matching according to each quality of service (QoS), Generating a corresponding number of orthogonal codes and mask codes according to a smallest bit transmission period among bit transmission periods (TTIs) of the respective transmission channels constituting the physical channel; Inputting a TFCI whose number of bits is predetermined by signal processing of a higher layer; Performing linear encoding by combining the input TFCI with the generated orthogonal codes and mask codes; TFCI encoding, comprising dividing the codewords generated by the encoding by the number of bits that can be transmitted through each radio frame, puncturing the divided codewords by a certain number of bits, and then transmitting them through the radio frames. It is about a method.

Transport Format Combination Identifier (TFCI), Lead-Muller Coding, Orthogonal Coding

Description

Transport Format Combination Identifier Encoding Method {method for encoding TFCI}

1 is a diagram illustrating a (32,10) TFCI encoding procedure according to the 3GPP standard.

2 is a diagram illustrating a (16,5) TFCI encoding procedure according to the 3GPP standard.

3 is a diagram illustrating a repetition pattern of a TFCI codeword according to the 3GPP standard.

The present invention relates to the next generation mobile communication, and more particularly, to an appropriate TFCI encoding method when a TFCI inserted in each time slot of a radio frame is transmitted in a mobile communication system using a W-CDMA scheme.

In general, a plurality of transport channels are classified according to their quality of service (hereinafter, referred to as QoS) to undergo channel coding and rate matching. After that, radio frames of these transport channels are multiplexed to form a data stream. More specifically, multiple transport channels that have undergone channel coding and rate matching according to respective QoSs are multiplexed. To be a Coded Composite Transport Channel (hereinafter referred to as CCTrCH). This means that one or more physical channels are mapped to CCTrCH.

Here, the bit transmission period of each transport channel is expressed as a transport time interval (hereinafter, abbreviated as TTI). During one TTI, all transport channels are successively connected and multiplexed with CCTrCH having the same timing as their own. It is transmitted through a physical channel in TTI units. The transport channels may have different TTIs.

At this time, the receiving side should detect the format of the transport channel. Therefore, the transmitting side should transmit the format information of several transport channels multiplexed by CCTrCH to the receiving side. TFCI is used at this time. Of course, the receiving side may or may not use TFCI to perform transport format detection.

If the TFCI is transmitted, the receiver detects a transport format combination from the TFCI, while if the TFCI is not transmitted, so-called blind transport format detection is performed.

After all, the TFCI is for informing the receiving side of the transport format combination of the CCTrCHs. The receiving side detects the TFCI to find the transmission format information and then decodes each of the transport channels. The transport format information includes the number of data of the transport channels, the TTI, the coding scheme, and the number of transport blocks.

In the Third Generation Partnership Project (hereinafter, abbreviated as 3GPP), which is a standardization organization for the next generation mobile communication system, the TFCI information bit for transmitting the above-mentioned transport format combination includes a second lead-muller code (second order). It is encoded using (32,10) subcode of Reed-Muller code or (16,5) Bi-orthogonal code, which is a first order Reed-Muller code. Coding procedures for this are shown in FIGS. 1 and 2.

The TFCI information bits vary from a minimum of 1 bit to a maximum of 10 bits, and the number of bits is determined at the time the call starts by signal processing of a higher layer.

These TFCIs are applied with different coding schemes depending on the number of bits determined by higher layer signal processing. That is, when the TFCI information bit is 5 bits or less, bi-orthogonal coding is applied, and when the TFCI information bit is 6 bits or more, second order Reed-Muller coding is applied.

1 is a diagram illustrating a (32,10) TFCI encoding procedure according to the 3GPP standard, illustrating an example of secondary read-muller coding used when the TFCI information bits are 6 bits or more and 10 bits or less.

First, when the TFCI information bit, which is a transport format information bit, is smaller than 10 bits, a padding procedure of first filling a missing bit value with the most significant bit (MSB) from "0" is first performed.

The TFCI information bits, which are 10 bits long by the padding procedure, are encoded using the (32, 10) subcode of the second order Reed-Muller code. That is, the TFCI information bit becomes a TFCI codeword of (32, 10) by read-muller coding that is linearly combined with base sequences of 10 bits in length.                         

Thereafter, the encoded 32-bit codeword is separately inserted and transmitted by 2 bits in each slot of the radio frame.

However, according to the current 3GPP standard, up to 30 bits can be transmitted because one radio frame consists of 15 slots. Therefore, all 32-bit codewords by Read-Mull coding cannot be transmitted. Accordingly, after read-muller coding, 2-bit puncturing is performed to generate a 30-bit codeword, which is then inserted into each slot by 2 bits and transmitted.

FIG. 2 is a diagram illustrating a (16,5) TFCI encoding procedure according to the 3GPP standard, and illustrates an example of quadrature coding, which is a primary read-muller coding used when the TFCI information bit is less than 6 bits and 1 bit or more. .

First, even if the TFCI information bit, which is the transport format information bit, is smaller than 5 bits, the padding procedure of filling the missing bit value from the most significant bit (MSB) to "0" as in the case of (32,10) TFCI encoding is performed. First it goes through.

The TFCI information bits, which are five bits long by the padding procedure, are encoded using the (16,5) orthogonal code. In other words, the TFCI information bits are (16,5) TFCI codewords by quadrature coding, which is linearly combined with base sequences in 5-bit units.

Thereafter, the encoded 16-bit codeword is separately inserted and transmitted by 1 bit in each slot of the radio frame.

As mentioned earlier, according to the current 3GPP standard, since one radio frame is composed of 15 slots, transmission of up to 15 bits is possible. Therefore, after orthogonal coding, 1-bit puncturing is performed to generate a 15-bit codeword, which is inserted into each slot one by one and then transmitted.

As a result, in the current 3GPP standard, one or two bits are inserted into each slot of one frame, and a TFCI codeword of 15 bits or 30 bits is transmitted in one frame.

However, when the spreading factor (SF) is smaller than 128, for example, a 30-bit TFCI codeword is repeatedly transmitted four times, which is illustrated in FIG. 3.

As can be seen from the repetition pattern of FIG. 3, in this case, the TFCI codewords are serially connected with (4,1) repetition codes.

In addition, another example of TFCI codeword repetitive transmission will be described. This is the case where the TTI is larger than 10 ms, that is, when the TTI is 20 ms, 40 ms, or 80 ms. Thus, even when the TTI is 20 ms or more, the same TFCI codeword is repeatedly transmitted over several frames.

Thus, when the TTI is 20 ms or more, it may be considered to be divided into a case in which there is a transport channel having a TTI of 10 ms and only a transport channel having a TTI of 20 ms or more.

First, when there is a transport channel having a TTI of 10 ms, the receiver decodes the received TFCI codeword in 10 ms units. The receiver collects the TFCI bits inserted into each slot, constructs a codeword, and decodes it to obtain format information of a transport channel. The obtained format information is used to obtain data of a transport channel mapped to various physical channels.

Second, when only a transmission channel having a TTI of 20 ms or more exists, the TFCI codeword is repeatedly transmitted in units of 10 ms. In this case, repetitive transmissions are performed over frames corresponding to the number of repetition bits forming one symbol.

As described above, the encoding of the TFCI codeword does not consider the TTI interval, but only the frame interval of 10 ms. Therefore, if there is a transport channel having a TTI larger than 10ms, the TFCI codeword is repeatedly transmitted a predetermined number of times.

However, the encoding scheme based on the repeated transmission of the TFCI codeword, as described above, does not show very good performance considering the word error rate (WER). This requires a new TFCI encoding scheme that is suitable for better performance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a TFCI encoding method operating in units of TTIs in consideration of different TTI intervals that each transport channel multiplexed with CCTrCH may have.

A feature of the TFCI encoding method according to the present invention for achieving the above object is, for one physical channel multiplexed with multiple channels through channel coding and rate matching according to each quality of service (QoS), Generating a corresponding number of orthogonal codes and mask codes according to the smallest bit transmission period among the bit transmission periods (TTIs) of the respective transmission channels; Inputting a transport format combination identifier (TFCI) whose bit number is predetermined by signal processing of a higher layer; Performing encoding by linearly combining the input transport format combination identifier (TFCI) with the generated orthogonal codes and mask codes; The codewords generated by the encoding are divided by the number of bits that can be transmitted through each radio frame, and the divided codewords are punctured by a predetermined number of bits and then transmitted through each radio frame.

Advantageously, the encoding step includes a corresponding number of bi-orthogonal codes and mask codes according to the smallest bit transmission period among the bit transmission periods (TTI) of the respective transmission channels constituting the physical channel. And encode the input transport format combination identifier (TFCI) by linear combination with the generated orthogonal codes and mask codes.

In the code generation step, different orthogonal codes and different numbers of mask codes are generated according to the smallest bit transmission period among bit transmission periods (TTIs) of the respective transmission channels constituting the physical channel.

Hereinafter, a preferred embodiment of the TFCI encoding method according to the present invention will be described with reference to the accompanying drawings.

Although the conventional TFCI encoding is operated by the frame unit of 10ms, TFCI encoding of the present invention operates by the TTI unit.

The TTI represents a bit transmission period of each transport channel. During one TTI, all transport channels are successively connected, multiplexed to the CCTrCH having the same timing as that of the transport channel, and then transmitted through the physical channel in units of the TTI.

In particular, each transport channel may have a different TTI. In particular, the present invention considers a codeword of the smallest TTI unit in a CCTrCH multiplexed with multiple transport channels of different TTIs. Here, the CCTrCH is a multiplexed multiple transport channels through channel coding and rate matching according to each QoS. Thus, one or more physical channels are mapped to CCTrCH.

As a result, the present invention performs TFCI encoding according to the smallest TTI among the TTIs of different transport channels, and the receiving side also performs TFCI decoding according to the smallest TTI.

Basically, in the TFCI of the present invention, different coding schemes are applied according to the number of bits (minimum 1 bit and maximum 10 bits) determined by the upper layer signal processing. That is, when the TFCI information bit is 5 bits or less, bi-orthogonal coding is applied, and when the TFCI information bit is 6 bits or more, second order Reed-Muller coding is applied.

In each coding according to the number of TFCI information bits of the present invention, the basic sequence linearly combined with the input TFCI information bits includes one code code in which all bit values are "1", and an orthogonal variable spreading factor; , Abbreviated as OVSF) code, and the following mask code. Table 1 below shows the basic sequence linearly combined with the input TFCI information bits. This is the case when the TTI is 10 ms.                     

TTI Base sequence 10 ms 1 ₃₂ , H _32,1 , H _32,2 , H _32,4 , H _32,8 , H _32,16 , M ₁ , M ₂ , M ₃ , M ₄

In the case of using such TFCI encoding, the basic codes (1 ₃₂ , H _32,1 , H _32,2 , H _32,4 , H _32,8 , H _{32, 16} ) and M mask codes according to the following equation (2) are generated.

In Equations 1 and 2, W denotes the length of a codeword that is adapted to the smallest TTI (10 ms). In addition, the sum of N and M is 10.

Table 2 below shows the basic sequences of the present invention which are linearly combined with the input TFCI information bits according to the TTI of each transport channel multiplexed by CCTrCH.

Minimum TTI Base sequence 10 ms 1 ₃₂ , H _32,1 , H _32,2 , H _32,4 , H _32,8 , H _32,16 , M ₁ , M ₂ , M ₃ , M ₄ 20 ms 1 ₆₄ , H _64,1 , H _64,2 , H _64,4 , H _64,8 , H _64,16 , H _64,32 , X ₁ , X ₂ , X ₃ 40 ms 1 ₁₂₈ , H _128,1 , H _128,2 , H _128,4 , H _128,8 , H _128,16 , H _128,32 , H _128,64 , Y ₁ , Y ₂ 80 ms 1 ₂₅₆ , H _256,1 , H _256,2 , H _256,4 , H _256,8 , H _256,16 , H _256,32 , H _256,64 , H _256,128 , Z ₁

Table 2 above includes a case where the TTI is 10 ms. In Table 2, 1 _p (1 ₃₂ , 1 ₆₄ , 1 ₁₂₈ , 1 ₂₅₆ ) has a length p (32, 64, 128, 256) and all bits. Is a code with value "1", H _{(p, q)} (H _32,1 , H _32,2 , H _32,4 , H _32,8 , H _32,16 , H _64,1 , H _64,2 , H _64,4 , H _64,8 , H _64,16 , H _64,32 , H _128,1 , H _128,2 , H _128,4 , H _128,8 , H _128,16 , H _128,32 , H _128,64 , H _256,1 , H _256,2 , H _256,4 , H _256,8 , H _256,16 , H _256,32 , H _256,64 , H _256,128 ) (p × q) This code is the bit value of the (q + 1) th column of the Hadamard matrix, and M _j (j = 1, 2, 3, 4) and X _j (j = 1, 2, 3) Y _j (j = 1, 2, 3) and Z _j (j = 1) are mask codes for the secondary lead-muller code.

In other words, in the present invention, according to the smallest TTI constituting the CCTrCH, the base codes 1 _p , H _{(p, q} ) and masks for different numbers of bi-orthogonal coding are generated and FIG. 1 is generated. Used for TFCI encoding.

As can be seen in Table 2, when the smallest TTI is 10 ms, the same basic code is shown as before, but when the TTI is 20 ms, 40 ms, or 80 ms, the basic code of Table 2 proposed by the present invention is used.

The following describes in more detail the TFCI encoding procedure according to the present invention.

Conventionally, a codeword corresponding to 10ms is generated and then repeatedly transmitted during the smallest TTI period.

However, in the present invention, the length of the generated TFCI codeword is made to fit the smallest TTI interval.

This will be described as an example when the TTI is 20 ms instead of the compressed mode.                     

First, a 10ms TFCI codeword is generated, and then repeatedly transmitted over two frames.

However, in the present invention, using the 20 ms basic code shown in Table 2, a secondary lead-muller codeword of (64, 10) corresponding to a 20 ms codeword is generated and then 4 bits are written in the (64, 10) codeword. Cherring Then, a puncturing (60, 10) codeword is transmitted over two frames.

An example will be described when the TTI is 40ms rather than the next compression mode.

In the present invention, first, a secondary lead-muller codeword of (128,10) corresponding to a 40ms codeword is generated using the 40ms basic code shown in Table 2, and then 8 bits are written in the (128,10) codeword. Cherish. Then, a puncturing (120, 10) codeword is transmitted over four frames.

An example will be described below in the case of the compression mode.

First, when in compression mode and the TTI is 20 ms.

Conventionally, a 10ms TFCI codeword is generated and transmitted twice over two frames.

However, in the present invention, using the 20ms basic code shown in Table 2, a second lead-muller codeword of (64,10) corresponding to a 20ms codeword is generated, and then the first 32 bits of (64,10) 32,10) codeword is transmitted in the first frame, and the remaining 32-bit (32,10) codeword is transmitted in the second frame.

In this case, in the divided transmission, a single radio frame is composed of 15 slots in the current 3GPP standard, so that up to 15 or 30 bits can be transmitted. Accordingly, 2-bit puncturing is performed on the (32, 10) codewords, and a 30-bit codeword is generated. Then, two bits are inserted into each slot of one frame and transmitted.

In compression mode, the TTI is transmitted in the same manner when 40 ms or 80 ms.

That is, in the present invention, using the 40ms basic code shown in Table 2, a secondary lead-muller codeword of (128,10) corresponding to a 40ms codeword is generated, and then the first 32 bits in the (128,10) codeword. The (32,10) codeword of is transmitted in the first frame, the (32,10) codeword of the second 32-bit is transmitted in the second frame, and the (32,10) codeword of the third 32-bit is The third frame is transmitted, and the remaining (32,10) codewords of the fourth 32 bits are divided and transmitted in the fourth frame.

Using the 80ms base code shown in Table 2 below, create a second lead-muller codeword of (256,10) that corresponds to a codeword of 80ms, and then use the first 32 bits of (32, 10) The codeword is transmitted in the first frame, the (32,10) codeword of the second 32 bits is transmitted in the second frame, and the (32,10) codeword of the third 32 bits is transmitted in the third frame. The fourth 32-bit (32,10) codeword is transmitted in the fourth frame, the fifth 32-bit (32,10) codeword is transmitted in the fifth frame, and the sixth 32-bit (32,10) codeword is transmitted. 10) The codeword is transmitted in the sixth frame, the seventh 32-bit (32,10) codeword is transmitted in the seventh frame, and the remaining eighth 32-bit (32,10) codewords are transmitted in the eighth frame. Send in divided.                     

In the end, when the bit of the TFCI codeword is a (i), the transmitted TFCI codeword b (i) is expressed as in Equation 3 below.

, i=0,1,...W-1

, i = 0,1, ... W-1

In Equation 3, _{Hi, n} is a basic code according to TTI.

The following Table 3 shows the secondary lead-muller codewords before puncturing in the present invention, and in particular, shows the minimum Hamming distance gain for each TTI of the secondary lead-muller codewords. For reference, the number of bits of the remaining TFCI codewords except for the secondary read-muller codewords shown in Table 2 is the same as the conventional hamming distance.

Minimum TTI Beneficial Hamming Distance Bits in the TFCI codeword  Conventional The present invention 10 ms - Same 20 ms 7 24 32 40 ms 7, 8 48 64 80 ms 7, 8, 9 96 128

As described above, in the TFCI encoding method according to the present invention, the encoding is performed in the smallest TTI unit constituting the CCTrCH instead of the 10 ms TTI unit in encoding the TFCI codeword. ), The encoding of the present invention is more efficient and shows better performance than the encoding scheme based on repetitive transmission of TFCI codewords.

In other words, gaining a hamming distance gain according to the number of bits of the TFCI codeword in each TTI leads to an improvement in encoding and transmission performance.

Claims (3)

The smallest bit transmission among the bit transmission periods (TTIs) of the respective transport channels constituting the physical channel for one physical channel multiplexed with several channel coding and rate matching according to each quality of service (QoS) Generating a corresponding number of orthogonal codes and mask codes according to a period; Inputting a transport format combination identifier (TFCI) whose bit number is predetermined by signal processing of a higher layer; Performing encoding by linearly combining the input transmission format combination identifier (TFCI) with the generated orthogonal codes and mask codes; And dividing the codewords generated by the encoding by the number of bits that can be transmitted through each radio frame, puncturing the divided codewords by a certain number of bits, and transmitting them through the respective radio frames. A transport format combination identifier encoding method. The method of claim 1, wherein the encoding step, Generates a corresponding number of bi-orthogonal codes and mask codes according to the smallest bit transmission period among the bit transmission periods (TTIs) of the respective transmission channels constituting the physical channel, and inputs the input transmission format. And a method of encoding a combination identifier (TFCI) by linearly combining the generated orthogonal codes and mask codes. The method of claim 1, wherein the code generation step, Transport format combination identifier, characterized in that different number of orthogonal codes and different number of mask codes are generated according to the smallest bit transmission period among the bit transmission periods (TTI) of the respective transmission channels constituting the physical channel Encoding method.

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