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990results about How to "Improve decoding performance" patented technology

Density evolution based polarization code constructing method and polarization code coding and decoding system

The invention discloses a density evolution based polarization code constructing method and polarization code coding and decoding system. According to the invention, the code length N and the information bit length K of an information code to be processed are obtained, an expectation value set of a log-likelihood ratio probability density function of N bit channels, K bit channels are selected as the information bit channels according to the expectation value set and information bit information index vector quantity is generated; an information bit sequence and a fixed bit sequence are mixed and the mixed bit vector quantity is multiplied by a polarization code for generating a matrix so as to output an encoding sequence; the encoding sequence is modulated and input into a transmission channel and the sequence output by the transmission channel is subjected to decoding operation by adopting a polarization code decoding algorithm, bit error probability and frame error rate of the decoded code are calculated and a design signal to noise ratio is changed, the above operation is repeated until the bit error probability and frame error rate become the minimum. The method and system provided by the invention are suitable for general binary system memoryless channels, the bit error probability and frame error rate are low, the calculation complexity is low and the communication performance of a communication system is improved.
Owner:SHENZHEN UNIV

Uniform and ununiform modulated constellation mapping based nonisoprotective mixed automatic retransmission inquiry method

A unequal protection hybrid automatic retransfer request method based on equality and un-equality constellation diagram mapping, it is used in MQAM communication system with which the stage numbers is M and M=2, the modulation mapping of sending end and the resolving mapping of receiving end adopt constellation diagrams that have same distribution, in the first transmission and anterior m/2-1 time retransmission, adopts equality constellation diagram, at the m/2 time and the latter retransmission adopts un-equality constellation diagram, provides higher error protection for two most significant bit in the modification symbol; the bits un-equality protection in the modification symbol of sending end reset; uses m/2 reset and opposite reset rules, at different retransmission time adopts circularly in turn, achieves alternative protecting the bits in modulation symbol; the bits in modulation symbol of receiving end reset oppositely. Reset oppositely the bits according to the reset rules of sending end, recover it into bits sequence soft value before sending end bits resetting. It promotes the signals S/N of combining soft value after demodulating and resolving mapping at receiving end, reduces efficiently grouping retransmission time, makes the output of system maximum.
Owner:SOUTHWEST JIAOTONG UNIV
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