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Soft Solution Preprocessing Method and Soft Solution Method of Constellation Mapping

A technology of constellation mapping and preprocessing, applied in the field of soft solution preprocessing of constellation mapping, can solve the problems of large amount of calculation, high cost of hardware implementation, and many system resources, etc.

Active Publication Date: 2015-08-12
TSINGHUA UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] It can be seen from the above that if the Max-Log-MAP method is used to obtain the log likelihood ratio of each bit in the information symbol, O(M) addition operations, O(M) multiplication operations, and O(MlogM) times are required Comparing operations, it can be seen that when the value of the mapping order M in the constellation diagram is large, the amount of calculation is large, which consumes a lot of system resources and the cost of hardware implementation is high.

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  • Soft Solution Preprocessing Method and Soft Solution Method of Constellation Mapping
  • Soft Solution Preprocessing Method and Soft Solution Method of Constellation Mapping
  • Soft Solution Preprocessing Method and Soft Solution Method of Constellation Mapping

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Embodiment 1

[0046] Such as figure 1 As shown, the soft solution preprocessing method of constellation mapping in this embodiment includes the following steps:

[0047] According to the constellation mapping adopted, the signal space containing 16 constellation points is divided into 4 regions; each region is distinguished by different shading, and the number in the center of each region represents the number of the region, and each region contains 4 constellation points; each information symbol contains 4 bits;

[0048] Construct table B; the constellation point set S used for logarithmic likelihood ratio calculation in area i is recorded in table B i ; i is an integer not greater than 4, i.e. i is 1, 2, 3 or 4; specifically as figure 1 Area 1, Area 2, Area 3 and Area 4 as described in;

[0049] in,

[0050] The S i Constellation Points Subset Included and the constellation point subset

[0051] said Contains the constellation point whose k-th bit is 0 and is the closest to th...

Embodiment 2

[0061] On the basis of the previous embodiment, the soft solution preprocessing method of constellation mapping in this embodiment provides two methods for obtaining the constellation point set,

[0062] The constellation point set S i The constellation points in are calculated by Monte Carlo algorithm or greedy algorithm.

[0063] Method 1: Monte Carlo algorithm to obtain:

[0064] Based on statistics and probability, the constellation point set is obtained through repeated verification;

[0065] Method 2: Greedy algorithm to obtain:

[0066] A: Define the distance from a point in the information symbol signal space to region i,

[0067] B: Then calculate as well as n is the nth bit of the information symbol, and n is not greater than log 2 The distance from all points in M ​​(M is the mapping order of the constellation map) to the area i, take the shortest several points as Represented as the i-th area, u represents the u-th bit of the received information symbol; ...

no. 1 example

[0074] The soft solution method for constellation mapping in this embodiment is applied after the preprocessing performed by the soft solution preprocessing method for constellation mapping above, and specifically includes the following steps:

[0075] Receive the information symbol and determine the area i to which the information symbol belongs;

[0076] Obtain the constellation point set S for the logarithmic likelihood ratio calculation of the region i to which the information symbol belongs from table B i , and according to the preset method for information symbols and S i The log-likelihood ratio is calculated for the constellation points in .

[0077] In the soft solution method of constellation mapping in this embodiment, table B for log likelihood ratio calculation is obtained through the soft solution preprocessing method of constellation mapping as described in embodiment 1 or embodiment 2, and table B The number of constellation points recorded in is much smaller...

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Abstract

The invention discloses a soft demapping pretreatment method and a soft demapping method for a constellation map. By the soft demapping pretreatment method and the soft demapping method, the problems of large operand, large occupancy of system resources, high implementation cost of hardware and the like in the conventional Max-Log-MAP are solved. The constellation mapped soft demapping pretreatment method comprises the following steps of: dividing signal space containing M constellation points into N areas according to the constellation map; and constructing a table B, and recording a constellation point set Si for the calculation of a log-likelihood ratio in an area i in the table B, wherein i is a positive integer which is smaller than or equal to N, Si comprises a constellation point subset, the constellation point subset contains a constellation point of which the k bit position is 0 and which is closest to the distance of a preset point in the area i, a constellation point of which the k bit position is 1 and which is closest to the distance of the preset point in the area i, and k is a positive integer which is smaller than or equality log2M. The soft demapping method comprises the following steps of: receiving and judging the area i to which an information symbol belongs; and reading the table B, and performing the calculation of the log-likelihood ratio on the information symbol and the constellation points in the Si in a preset method.

Description

technical field [0001] The invention relates to the field of digital information communication, in particular to a soft solution preprocessing method and a soft solution method for constellation mapping. Background technique [0002] The soft solution method of the most commonly used constellation mapping at present comprises the following steps: [0003] Step 1: Receive information symbols; [0004] Step 2: According to each bit in the information symbol and each constellation point in the signal space, calculate the log likelihood ratio through formula (2). This method is called Max-Log-MAP algorithm; [0005] The log likelihood ratio LLR (Log-Likelihood Ratio) is often used to express the soft information of each bit in the information symbol; [0006] For a certain bit b, its log-likelihood ratio is defined as: [0007] LLR ( b ) = log P ( ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/36H04L1/00
Inventor 彭克武陈霜黄嘉晨潘长勇宋健
Owner TSINGHUA UNIV