A latency reduced method is proposed based on the modified successive cancellation (MSC) decoder for decoding polar codes. In the MSC decoder, it was shown that latencies for both the rate-zero and the rate-one nodes can be reduced. By redistributing the information bits, the proposed method can obtain a good rate-zero and rate-one nodes distribution, in which decoding latency can be further reduced under the MSC decoder. Simulation results show that the new polar code (obtained by the proposed method) achieves 8.5% latency reduction with neglected error performance loss compared with the original polar code. Furthermore, it is easy to adjust the trade-off between the error performance and decoding latency by the proposed method.Introduction: Recently, polar codes [1] have attracted a great deal of interest since they are the first codes to provably achieve channel capacity with low-complexity encoding and decoding algorithms in a diverse set of scenarios. Although theoretically very interesting, polar codes have some drawbacks practically. Because of the nature of sequential decoding, the traditional successive cancellation (SC) decoders suffer from a very high latency. In [2], it has been shown that the latency of a rate-one node (introduced later on) can also be reduced like a rate-zero node, in which significant latency reduction is achieved with no sacrifice in error performance. For a polar code with fixed block length, the rate-one and rate-zero nodes distribution is determined by the information set. In this Letter, we propose a method to give a minor adjustment to the original information set and to obtain a new information set with good rate-zero and rate-one nodes distribution, in which decoding latency can be further reduced with small performance loss compared with the original information set.

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