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System and method for spreading on fading channels

A square, symbol technology, applied in the field of data transmission, can solve the problems of increased complexity at the receiver end, no fading channel performance damage, and no Rayleigh fading channel performance improvement.

Inactive Publication Date: 2010-06-23
BROADCOM CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current techniques for improving the performance of Rayleigh fading channels both damage the performance of non-fading channels and cannot significantly improve the performance of Rayleigh fading channels.
Other possible techniques, such as enhanced coding, would significantly increase the complexity at the receiver

Method used

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  • System and method for spreading on fading channels
  • System and method for spreading on fading channels
  • System and method for spreading on fading channels

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Embodiment Construction

[0096] The present invention relates to data transmission in a radio frequency communication system, in particular to a method for mapping data bits to information symbol values ​​before transmission, so as to reduce the negative effect caused by fading when the information symbols are restored at the receiver.

[0097] According to an exemplary embodiment of the present invention, the improved coding scheme may include combining two symbols x1 and x2 that are subjected to different degrees of fading by multiplying with a matrix of order 2x2, as follows:

[0098] y 1 y 2 = 2 1 1 - 2 ...

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Abstract

The invention discloses a simple spreading technique that improves performance for communication over fading channels with QPSK or BPSK modulation. The technique may comprise combining two symbols at the transmitter by applying a 2 multiply 2 transform, resulting in a 4-PAM or 16-QAM constellation. The receiver may utilize a 2-dimensional soft de-mapper to provide inputs to a soft-input decoder. This scheme can offer significant performance gains over fading channels with minimal additional complexity. This technique is most beneficial on systems with a weak code or nocode at all. One application of this technique is for coded OFDM systems that experience frequency-selective fading. An example of such a system is the MBOA draft specification for UWB wireless communications.

Description

technical field [0001] The present invention relates to data transmission using a radio frequency communication system, and specifically relates to a method for mapping data bits to information symbol values ​​before transmission, so as to reduce the negative effect of fading when a receiver recovers information symbols. Background technique [0002] Many radio frequency (RF) communication systems suffer from transmitted symbol fading, which causes different symbols to be received with unequal amplitudes (and / or unequal noise levels). A common example is that Coded Orthogonal Frequency Division Multiplexing (Coded OFDM or COFDM) transmitted over a communication channel suffers from multipath interference. In this example, the transmitted signal suffers from frequency-selective fading. When the multipath interference is dense enough (that is, the received signal includes a large number of signals, each of which has a different path delay), this fading can be accurately model...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L25/49H04L27/26H04L5/12H04L5/06H04L27/20H04L27/18H04L1/04
CPCH04L27/20H04L27/186H04L27/2602H04L5/06H04L27/2603
Inventor 艾瑞克·J·欧贾德
Owner BROADCOM CORP