KR20050064486A - Method for block interleaving in cdma mobile communication system - Google Patents

Abstract

The present invention relates to a method for detecting an index before being interleaved from a modulation index of an arbitrary position in an interleaver, the method comprising: a first step of generating a corresponding index according to a modulation request for an arbitrary position of a symbol grouping block; A second step of dividing the index by the size of a packet and calculating a quotient and a remainder according to the size; and a third step of selecting a corresponding block including the index by using the calculated quotient and a remainder; It is characterized in that it comprises a fourth step of calculating the corresponding index in each sub-block.

Description

Method for block interleaving in code division multiple access mobile communication system {Method for Block Interleaving IN CDMA Mobile Communication System}

The present invention relates to an interleaving method in a mobile communication system, and more particularly, to a block interleaving method in a communication system of 1xEV (Evolution) -DV (Data Voice), which is a packet data and voice support protocol.

In the communication system, if an error occurs in the data during transmission, recovery is impossible and the data is not available. In order to minimize the error, an error correction technique is used. Turbo codes can be recovered when errors are interspersed. However, if errors are concentrated in a certain part, the turbo codes cannot be corrected by error correction codes. No matter how good an error-correcting code is, you can't prevent the loss of consecutive data all at once if errors are concentrated in a particular area.

However, random distribution of continuous data using an interleaver can minimize the burst error.

In CDMA2000, a block interleaver is used to implement such an interleaver. 1 is a conceptual diagram illustrating the principle of a block interleaver. A principle of block interleaving in the block interleaver will be described with reference to FIG. 1.

When the data to be transmitted is 1, 2, 3, 4 ... 20, the input is written in the horizontal direction and the output is in the vertical direction. This sorting of data is called interleaving. Data output through the block interleaver is 1, 6, 11, 16/2, 7, 12, 17/3, 8, 13, 18/4, 9, 14, 19/5, 10, 15, 20 and encrypted Go through the process. Even if the 1, 6, 11, 16 sent first during the transmission is broken, * 2, 3, 4, 5 / * 7, 8, 9, 10 / * 12, 13, 14, 15 / Error recovery is possible because the errors are distributed by deinterleaving to 17, 18, 19, and 20.

If data is transmitted consecutively like 1, 2, 3, 4, 5 without interleaving, and data from 1 to 10 is corrupted, error correction encoding is performed so that the previous data is corrupted even if it is related to the previous bit. Can not be recovered. This intensive occurrence of errors in certain parts is called burst error, and infrequent errors are called random errors. That is, the block interleaver serves to randomize the burst error.

That is, the interleaver stores the code code that has been scrambled using a memory device and then performs interleaving according to a predetermined rule. The interleaved code codes can guarantee a certain reliability from congestion errors that may occur in a wireless environment.

The sub-block channel interleaver included in the IS-2000 Release C (1xEV-DV) F / L spec. Is an existing channel interleaver included in the previous IS-2000 Release A / B spec. P-BRO (partial bit reversal order) operation is performed for row permutation like interleaver, but functional read address generation method should be slightly different. The difference between the selection of the parameters is that the impact on QCTC (Quasi-Complementary Turbo Codes) symbol selection must be fully considered.

2 is a block diagram illustrating an interleaver of the aforementioned 1xEV-DV system packet data channel (PDCH). Let's look at the interleaver in more detail with reference to FIG.

The interleaver includes a sub block memory 30 to temporarily store bits output from the turbo encoder, an interleaver memory 31, and a temporary memory 32 used for symbol grouping.

The encoded data output from the turbo encoder is first separated into symbols. The first symbol of the turbo encoded output is an S block, the second symbol is a P0 block, the third symbol is a P1 block, the fourth symbol is a P0 'block, and the fifth symbol is a P1'. Sort blocks in order. Then, it is stored in each of the subblock memories 30.

Data sequentially stored in the subblock memory 30 is loaded in the order of interleaving from the subblock memory in the following order.

In the interleaved symbol, the i-th symbol is sequentially read by an address calculated by the following method, that is, Ai (i = 0 to N_int-1).

1. Referring to Table 1 below, determine the subblock interleaver parameters m and J.

Encoder Packet subblock interleaver parameter N_int m J 408 408 7 4 762 792 8 4 1560 1560 9 4 2328 2328 10 3 3096 3096 10 4 3864 3864 11 2

        2. Initialize i and k to zero.

3. Create an output address using Equation 1 below.

4. If created end Less than And increase i and k by 1, respectively. Otherwise Throw away and only increase k.

5. All Repeat steps 3 and 4 until you get the interleaver output for.

In general, the output from the turbo encoder is modulated after symbol separation, symbol interleaving, and symbol grouping. In practice, due to space constraints, instead of using memory at each step, the output from the turbo encoder is stored in memory, and then the symbol address, symbol interleaving, and symbol grouping process are used to calculate the address. You will perform a series of interleaving tasks. In this case, if the address of the memory is made one by one while increasing the counter from 0 to 7799 in the process of calculating the interleaving address, the discarded addresses are generated due to the characteristics of the interleaver so that a maximum of 2440 clocks (based on encoder size 2328) are lost. There is a problem.

Accordingly, an object of the present invention for solving the above problems is to use the sub-block interleaver memory and the memory for symbol grouping when the data of any position of the modulated data stream is requested, and the arbitrary position. The present invention provides a method of efficiently searching for data.

In order to achieve the above object, the present invention provides a method for detecting an index before being interleaved from a modulation index of an arbitrary position in an interleaver, wherein the index is generated according to a modulation request for an arbitrary position of a symbol grouping block. A second step of dividing the index by the size of each input packet and calculating a quotient and remainder according to the first step; and using the calculated quotient and remainder, selecting a corresponding block including the index. And a fourth step of calculating a corresponding index in each subblock using the remainder.

Hereinafter, the detailed operation and structure of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that reference numerals and like elements among the drawings are denoted by the same reference numerals and symbols as much as possible even though they are shown in different drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The present invention proposes a method for finding an index of a subblock before a symbol is interleaved for data at an arbitrary position in a symbol grouped data stream.

3 shows a configuration of an interleaver according to the present invention. The interleaver 100 according to the present invention is used to temporarily rearrange the register 110 to store the bit output from the scrambler according to the code rate, the interleaver memory 120, the end around shift, and BRO. It is configured to include a memory (130).

In the interleaver 100 configured as described above, the turbo-encoded and scrambled output is first sorted by S, P0, P1, P'0, and P'1 according to the code rate in the order of S, P0, P'0, P1, and P'1. Then, after storing them in each interleaver memory 120, using the temporary memory 130 to perform interleaving of each block to output to the modulator 200.

Interleaver memory (12288bit, 11) may be composed of three sub-blocks (block_S, block_P0 / P'0, block_P1 / P'1), the data coded by the turbo encoder and scrambled by the scrambler to the interleaver 100 If input, the data is sequentially rearranged (symbol reorder) and stored in the corresponding location for each block.

The temporary memory 130 generates an address in which each data is stored in order to read data sequentially stored in the interleaver memory 120 in the interleaved order corresponding to the read signal of the modulator. In accordance with the generated address, the modulator 200 receives data stored at the address and performs modulation. That is, the interleaver 100 generates an address and reads symbols in the order of interleaving with the address generated according to the read clock of the modulator 200.

The present invention is a method for calculating an index before interleaving of a symbol stored in a temporary memory according to the request of the modulator 200 as described above, and the operation thereof will be described in detail with reference to FIG. 4.

Referring to FIG. 4, in response to the request of the modulator 200 for an arbitrary position (hereinafter, referred to as an arbitrary modulation index) of the symbol grouping block, the interleaver 100 generates a modulation index of an arbitrary position in step 300. In step 301, the interleaver 100 calculates the quotient and remainder using N_int given by Table 1 according to the size of each input packet. That is, the sub-block corresponding to the size of the input packet according to the <Table 2> is selected.

Share (q) Remainder Selection block 0 S One odd number P0 upper Even P0 'upper 2 odd number P0 lower Even P0 'lower 3 odd number P1 upper Even P1 'upper 4 odd number P1 lower Even P1 'lower

Referring to Table 2, if the quotient is zero, an S block is selected. Referring to FIG. 2, only the S block is included in the first interleaved block. Therefore, all symbols having index values from 0 to N_int are values included in the S block.

When the quotient is' 1 ', PO upper or PO' upper is selected according to the remaining values, for the following reason.

Referring to FIG. 2, the values of the P0 subblock are arranged in the first order in the first block through interleaving, and then the symbols of the P0 'subblock are arranged in the second order of the first block. That is, in the first block, symbols of the PO subblock and the PO 'subblock are alternately arranged. Accordingly, a value having an odd number in the first sub block becomes an upper symbol of a P0 sub block, and a value having an even number in the first sub block becomes an upper symbol of a PO ′ sub block.

If the quotient is 2, PO lower or PO 'lower is selected according to the remaining value, and since the P0 lower block and P0' lower block are alternately arranged in the second subblock, odd values are included in the lower block of P0. This is because the even value is a symbol interleaved from the P0 'lower block.

If the quotient is 3, P1 upper or P1 'upper is selected according to the remaining values. If the quotient is 4, P1 lower or P1' lower is selected according to the remaining values. Same as 1 or 2.

In step 302, the interleaver 100 selects the corresponding block including the index with reference to Table 2 as described above, using the quotient and the remainder calculated in step 301. In step 303, the interleaver 100 finds a corresponding index in each subblock using the remainder. Then, the index before the interleaving can be obtained by adding the index allocated to the previous block to the index calculated in each block.

As described above, the present invention does not require the use of additional subblock interleaver memory, symbol group memory, or the like, and it is not necessary to perform these processes sequentially, thereby saving time.

1 is a conceptual diagram illustrating the principle of a block interleaver;

2 is a view for explaining the operation of the block interleaver;

3 is a block diagram of an interleaver according to the present invention;

4 is an operational flowchart for obtaining an index in a subblock according to the present invention.

Claims (1)

The present invention relates to a method for detecting an index before being interleaved from a modulation index of an arbitrary position in an interleaver. A first step of generating a corresponding index according to a modulation request for an arbitrary position of a symbol grouping block; Dividing the index by the size of each input packet and calculating a quotient and a remainder according thereto; Using the calculated quotient and the remainder, selecting a corresponding block including the index; And a fourth step of calculating a corresponding index in each subblock using the remainder.