Browsing by Subject "Code rates"

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    An FPGA implementation architecture for decoding of polar codes
    (IEEE, 2011) Pamuk, Alptekin
    Polar codes are a class of codes versatile enough to achieve the Shannon bound in a large array of source and channel coding problems. For that reason it is important to have efficient implementation architectures for polar codes in hardware. Motivated by this fact we propose a belief propagation (BP) decoder architecture for an increasingly popular hardware platform; Field Programmable Gate Array (FPGA). The proposed architecture supports any code rate and is quite flexible in terms of hardware complexity and throughput. The architecture can also be extended to support multiple block lengths without increasing the hardware complexity a lot. Moreover various schedulers can be adapted into the proposed architecture so that list decoding techniques can be used with a single block. Finally the proposed architecture is compared with a convolutional turbo code (CTC) decoder for WiMAX taken from a Xilinx Product Specification and seen that polar codes are superior to CTC codes both in hardware complexity and throughput. © 2011 IEEE.
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    On capacity and coding for segmented deletion channels
    (IEEE, 2011) Wang, F.; Aktaş, Defne; Duman, T. M.
    We consider binary deletion channels with a segmentation assumption which appears to be suited for more practical scenarios. Unlike the binary independent and identically distributed (i.i.d.) deletion channel where each bit is independently deleted with an equal probability, the segmentation assumption prohibits certain transmitted bits to be deleted, i.e., in a block of bits of a certain length, only a limited number of deletions can occur. We first propose several upper and lower capacity bounds for the segmented deletion channel. Then we focus on an interleaved concatenation of an outer low-density parity check (LDPC) code with error-correction capabilities and an inner marker code with synchronization capabilities over these channels. With the help of a specifically designed maximum-a-posteriori (MAP) detector, we demonstrate reliable transmission at higher code rates than the existing ones reported in the literature.