Method for encoding sequence of blocks of input bits to be transmitted over wireless channel

Abstract

A method encodes a sequence of blocks of input bits to be transmitted over a wireless channel. Each block of input bits is converted to a codeword, and each codeword is mapped to multiple sub-blocks of complex numbers. Each sub-block is multiplied by a disambiguating spreading transform to obtain a sub-block of transformed symbols, which can be modulated and transmitted to a receiver, where each received block is demodulated to a block of complex numbers, which are partitioned into sub-blocks. The sub-block of complex numbers are converted to a set of likelihood ratios that correspond to decoded codewords. The input bits can be decoded unambiguously even if only one of the blocks of symbols corresponding to the block of input bits is received correctly.

Description

Method for encoding an input bit-block sequence to be transmitted over a wireless channel technical field The present invention relates generally to encoding radio signals, and more particularly to encoding signals to be transmitted over radio channels subject to fading, interference and noise. Background technique Wireless communication Wireless communication devices offer a level of convenience and mobility unmatched by wired devices. However, wireless communication systems also suffer from certain problems that do not arise to the same extent with wired systems. Among these problems, the most serious problem is fading. Fading is the temporal variation of the channel state. The second problem is the interference that occurs between multiple signals using the same portion of the spectrum at the same time. As the transmission rate of wireless communication continues to increase, the frequency selectivity of wireless channels becomes a major issue. A "frequency-selec...

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Problems solved by technology

The second problem is the interference that occurs between multiple signals using the same portion of the spectrum simultaneously

However, in many practical situations, none of the above approaches is optimal or even feasible

The first approach requires immediate channel state information at the transmitter, which would impose large feedback overhead and a large set of modulation alphabet symbols, thereby imposing hardware limitations

The second method requires encoding over a long time, which is inappropriate in many cases, especially when long delays cannot be tolerated

However, none of the methods in the prior art can be used to spread symbols over more than two channels without encountering the problem of uncertainty when some subcarriers are in deep fading

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