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Method for balancing orthogonal frequency division multiplexing signals

An orthogonal frequency division and signal multiplexing technology, which is applied in equalizers, shaping networks in transmitters/receivers, baseband system components, etc., can solve the problem of high complexity of equalization methods and inability to apply multiple input and multiple output, etc. problems, to achieve the effect of increasing speed and reducing complexity

Inactive Publication Date: 2007-04-04
PANASONIC CORP
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0017] However, when the channel length is greater than CP, due to the high complexity of the existing equalization method, it cannot be applied to a multiple-input multiple-output (MIMO) system, and can only be used in a single-input single-output (SISO) system

Method used

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  • Method for balancing orthogonal frequency division multiplexing signals
  • Method for balancing orthogonal frequency division multiplexing signals
  • Method for balancing orthogonal frequency division multiplexing signals

Examples

Experimental program
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Effect test

no. 1 example

[0142] The first example (M×M OFDM system)

[0143] The specific equalization process in the case where CP is not 0 is described below.

[0144] 1) In step S401, according to the estimation of the previous symbol, get (currently k), according to formula (8), through decision feedback, the current estimate of the received signal for eliminating inter-symbol interference is obtained.

[0145] 2) In step S402, according to formula (9), a zero-forcing equilibrium solution b is obtained using a fast algorithm. Since the description of the fast algorithm of the calculation step S402 is complicated, it will be given separately later.

[0146] 3) In step S403, use the CP segment to combine the equalized signal b, the detailed process is as follows:

[0147] b is a column vector of M(N+P)×1, let v be a column vector of MN×1, then:

[0148] v(1:M(N-P))=b(1+MP:MP+M(N-P)) (34-1)

[0149] v(M(N-P)+1:MN)=0.5×(b(1:MP)+b(MN+1:M(N+P))) (34-2)

[0150] 4) In step S404, transform the time...

no. 2 example

[0207] The second example (1×1 OFDM system)

[0208] The equalization method in the case of no CP is described below.

[0209] In the case of no CP, the processing model is the same as in Reference 1.

[0210] Likewise, as shown in FIG. 3 , the following three processes need to be performed in this example.

[0211] 1) Judgment feedback process

[0212] From formula (4), we have:

[0213] d = y k - H 2 Q H s ~ k - 1 - - - ( 41 )

[0214] In formula (5), y k is the receiving vector of the kth OFDM symbol. For the estimation vector of the transmitted symbol on the k-1th OFDM symbol (the estimation of the transmitted symbol on all subcarriers in the ...

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Abstract

The method is used in an OFDM system with M sending antennas and M receiving antennas (M>=1) and comprises: getting the signals processed by using decision direct feedback approach based on the decision of previous symbol and removing the interference between signals; solving the first block column of inverse matrix of channel matrix by solving the equation set; picking up different part from the signal processed with decision feedback according to its corresponding antenna, and getting a corresponding part form the first block column of the inverse matrix of channel matrix as the linear convolution; combining the convolution results obtained from each part to get the balanced signals.

Description

technical field [0001] The invention relates to an equalization technique in an Orthogonal Frequency Division Multiplexing (OFDM) system, in particular to a low-complexity equalization method capable of reducing equalization time. Background technique [0002] Orthogonal frequency division multiplexing is an efficient data transmission method. Its basic idea is to divide a given channel into many orthogonal sub-channels in the frequency domain, use a sub-carrier for modulation on each sub-channel, and each sub-carrier is parallel transmission. In this way, although the overall channel is non-flat and has frequency selectivity, each sub-channel is relatively flat, and narrowband transmission is performed on each sub-channel, and the signal bandwidth is smaller than the corresponding bandwidth of the channel, so the signal waveform can be greatly eliminated. Interference between. [0003] The difference between OFDM and general multi-carrier transmission is that it allows su...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/01H04L25/03
Inventor 吴强李继峰
Owner PANASONIC CORP