Near‐Capacity Variable‐Length Coding

2015 IEEE International Conference on Communications (ICC)

et al. 2015

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Abstract-Unary Error Correction (UEC) codes constitute a recently proposed Joint Source and Channel Code (JSCC) family, conceived for alphabets having an infinite cardinality, whilst out-performing previously used Separate Source and Channel Codes (SSCCs). UEC based schemes rely on an iterative decoding process, which involves three decoding blocks when concatenated with a turbo code. Owing to this, following the activation of one of the three blocks, the next block to be activated must be chosen from the other two decoding block options. Furthermore, the UEC decoder offers a number of decoding options, allowing its complexity and error correction capability to be dynamically adjusted. It has been shown that iterative decoding convergence can be expedited by activating the specific decoding option that offers the highest Mutual Information (MI) improvement to computational complexity ratio. This paper introduces an iterative demodulator, which is shown to improve the associated error correction performance, while reducing the overall iterative decoding complexity. The challenge is that the iterative demodulator has to forward its soft-information to the other two iterative decoding blocks, and hence the corresponding MI improvements cannot be compared on a like-for-like basis. Additionally, we also propose a method of eliminating the logarithmic calculations from the adaptive iterative decoding algorithm, hence further reducing its implementational complexity without impacting its error correcting performance.

Section: Introductionmentioning

confidence: 99%

Adaptive iterative detection for expediting the convergence of a serially concatenated Unary Error Correction decoder, turbo decoder and an iterative demodulator

Brejza

2015 IEEE International Conference on Communications (ICC)

et al. 2015

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“…For example, the n = 2-bit codewords C = {01, 11, 11} are employed in the r = 6-state UEC trellis of Fig As shown in Figure 1, the UEC-encoded bit vector z may be interleaved in the block π 1 of Figure 1, IrURC encoded [6], [8] and then interleaved as usually punctured in the block π 2 . In accordance with convention, the coding rate R i of this process is given by the number of input bits per output bit.…”

Section: Transmitter and Receiver Operationmentioning

confidence: 99%

“…An iteratively-decoded serial concatenation of the proposed UEC code and an Irregular Unity Rate Code (IrURC) [6] is capable of asymptotically eliminating the capacity loss, as the complexity of the UEC is increased. In [3], a JSCC UEC code was compared to a Separate Source and Channel Coding (SSCC) benchmarker, which employs an EG source code and a separate Convolutional Code (CC).…”

Section: Introductionmentioning

confidence: 99%

On the complexity of Unary Error Correction codes for the near-capacity transmission of symbol values from an infinite set

2013 IEEE Wireless Communications and Networking Conference (WCNC)

Hanzo

2013

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Abstract-Unary Error Correction (UEC) codes have recently been proposed for the near-capacity Joint Source and Channel Coding (JSCC) of symbol values that are selected from a set having an infinite cardinality. In this paper, we characterize the computational complexity of UEC decoders and use complexity analysis for striking a desirable trade-off between the contradictory requirements of low complexity and near-capacity operation. We investigate a wide range of application scenarios and offer a deep insight into their beneficial parameterizations. In particular, we introduce puncturing for controlling the scheme's throughput and for facilitating fair comparisons with a Separate Source and Channel Coding (SSCC) benchmarker. The UEC scheme is found to offer almost 1.3 dB gain, when operating within 1.6 dB of the capacity bound. This is achieved without any increase in transmission energy, bandwidth, transmit duration or decoding complexity.

“…Inspired by this, the splitter S of Figure 1 decomposes each symbol d i in the vector d into two sub-symbols, namely into x i and t i according to (6) and (7), where…”

Section: A Decomposition Of Symbols Into Pairs Of Sub-symbolsmentioning

confidence: 99%

“…For example, this may be achieved by combining a near-entropy source code, such as an adaptive arithmetic code [2] or a Lempel-Ziv code [3], with a near-capacity channel code, such as a Low Density Parity Check (LDPC) code [4] or a turbo code [5]. However, the source-channel separation theorem relies upon a number of assumptions, which may not be valid in practice [6]. For example, near-entropy adaptive arithmetic coding or Lempel-Ziv coding requires both the transmitter and receiver to accurately estimate the occurrence probability of every value that is adopted by the symbols that the source produces.…”

mentioning

confidence: 99%

Near-Capacity Joint Source and Channel Coding of Symbol Values from an Infinite Source Set Using Elias Gamma Error Correction Codes

Wang

et al. 2014

IEEE Trans. Commun.

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Abstract-In this paper we propose a novel low-complexity Joint Source and Channel Code (JSCC), which we refer to as the Elias Gamma Error Correction (EGEC) code. Like the recentlyproposed Unary Error Correction (UEC) code, this facilitates the practical near-capacity transmission of symbol values that are randomly selected from a set having an infinite cardinality, such as the set of all positive integers. However, in contrast to the UEC code, our EGEC code is a universal code, facilitating the transmission of symbol values that are randomly selected using any monotonic probability distribution. When the source symbols obey a particular zeta probability distribution, our EGEC scheme is shown to offer a 3.4 dB gain over a UEC benchmarker, when Quaternary Phase Shift Keying (QPSK) modulation is employed for transmission over an uncorrelated narrowband Rayleigh fading channel. In the case of another zeta probability distribution, our EGEC scheme offers a 1.9 dB gain over a Separate Source and Channel Coding (SSCC) benchmarker.