The concatenation of low-density parity-check and Reed-Solomon codes for forward error correction has been experimentally demonstrated for the first time in this letter. Using a 2-bit soft-decision large-scale integra...
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The concatenation of low-density parity-check and Reed-Solomon codes for forward error correction has been experimentally demonstrated for the first time in this letter. Using a 2-bit soft-decision large-scale integration and high-speed field-programmable gate arrays, a net coding gain of 9.0 dB was achieved with 20.5% redundancy with four iterative decoding for an input bit-error rate of 8.9 x 10(-3) at 31.3 Gb/s.
Power-line networks are proposed for broadband data transmission. The presence of multipaths within the broadband power-line communication (BPLC) system, due to stochastic changes in the network load impedances, branc...
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Power-line networks are proposed for broadband data transmission. The presence of multipaths within the broadband power-line communication (BPLC) system, due to stochastic changes in the network load impedances, branches, etc. pose a real challenge as it affects network performance. This paper attempts to investigate the performance of an orthogonal frequency-division multiplexing (OFDM)-based BPLC system that uses underground cables. It is found that when a branch is added in the link between the sending and receiving end, there is an average of 4-dB power loss. In addition, when the terminal impedances of the branches that are connected to the link between the transmitting and receiving end vary from line characteristic impedance to low-impedance values, the power loss (signal-to-noise ratio) is about 0.35 dB/Omega. On the contrary, for an increase in the terminal impedances by 100 Omega above line characteristic impedance, the power loss is 0.23 dB/Omega. When the branch terminal impedances are close to short or open circuits, OFDM techniques show degraded performance. This situation is also observed when the number of branches increases. It is shown that to overcome degraded network performance, the concatenated Reed-Solomon codes/interleaved Viterbi methods can be used, which could be used for an efficient design of the BPLC system that uses OFDM techniques.
Implementation of concatenate code has various problems such as frame synchronization and clock utilization for design on the FPGA chip. This paper proposed an efficient design methodology for serial concatenation cod...
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ISBN:
(纸本)9781424436927
Implementation of concatenate code has various problems such as frame synchronization and clock utilization for design on the FPGA chip. This paper proposed an efficient design methodology for serial concatenation coding of cable systems and fabrication on the FPGA chip Vertex II pro xc2vp30-5, Xilinx.
This paper focuses on the uplink of multicell IEEE 802.16-d WiMax systems with OFDM modulation and antenna array at the base stations. We propose an analytical framework to assess the average error probability of all ...
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ISBN:
(纸本)9781424414833
This paper focuses on the uplink of multicell IEEE 802.16-d WiMax systems with OFDM modulation and antenna array at the base stations. We propose an analytical framework to assess the average error probability of all the different transmission modes over space-time dispersive Rayleigh fading channels. The proposed method takes into account the effects of the multilevel modulation, the error correction capability of the concatenated code, the interleaving scheme, the power-angle structure of the inter-cell interference and the array processing at the base station. Simulation results corroborate the proposed analysis for a IEEE 802.16-d cellular system over different propagation scenarios.
It has been demonstrated that turbo codes substantially outperform other codes, e.g., convolutional codes, both in the non-fading additive white Gaussian noise (AWGN) channel as well as multiple-transmit and multiple-...
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It has been demonstrated that turbo codes substantially outperform other codes, e.g., convolutional codes, both in the non-fading additive white Gaussian noise (AWGN) channel as well as multiple-transmit and multiple-receive antenna fading channels. Moreover, it has also been reported that turbo codes perform very well in fast fading channels, but perform somewhat poorly on slow and block fading channels of which the broadband fixed wireless access (FWA) channel is an example. In this paper, we thoroughly compare the performance of turbo-coded and convolutional-coded broadband FWA systems both with and without antenna diversity under the condition of identical complexity for a variety of decoding algorithms. In particular, we derive mathematical expressions to characterize the complexity of turbo decoding based on state-of-the-art Log-MAP and Max-Log-MAP algorithms as well as convolutional decoding based on the Viterbi algorithm in terms of the number of equivalent addition operations. Simulation results show that turbo codes do not offer any performance advantage over convolutional codes in FWA systems without antenna diversity or FWA systems with limited antenna diversity. Indeed, turbo codes only outperform convolutional codes in FWA systems having significant antenna diversity.
In this paper, we present a novel concatenated trellis coded modulation (CTCM) scheme for limited diversity order fading channels. Examples for such channels include those encountered in indoor wireless networks like ...
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In this paper, we present a novel concatenated trellis coded modulation (CTCM) scheme for limited diversity order fading channels. Examples for such channels include those encountered in indoor wireless networks like IEEE 802.11. It is first shown that when the diversity order afforded by the channel is fixed, bit interleaved coded modulation (BICM) is no longer the best way to encode. We then develop CTCM, which is superior to both BICM and conventional TCM of similar complexities. Unlike conventional TCM where convolutional codes are designed over modulated signal sets, CTCM has TCM concatenated to short length inner codes. Each trellis branch in the TCM now corresponds to a short block-code. We discuss design of good inner codes that allow for simple decoders. CTCM design incorporates useful features of both BICM and conventional TCM. Code design is explained with examples. Simulation results and information theoretic supporting the arguments are shown.
Turbo space-time codes with symbols precoded by randomly chosen unitary time variant linear transformations (TVLT) are investigated in this paper. It is shown that turbo codes with TVLT achieve full diversity gain and...
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Turbo space-time codes with symbols precoded by randomly chosen unitary time variant linear transformations (TVLT) are investigated in this paper. It is shown that turbo codes with TVLT achieve full diversity gain and do not require exhaustive tests of the rank criterion. We prove that the coding gain performance of turbo space-time codes with TVLT improves with the Hamming distance between codewords (number of different columns). As an additional benefit of the application of TVLT, with the removal of the constant modulation condition, we prove that throughput rates achieved by these codes are significantly higher than those for conventional space-time codes. Numerical results are provided to demonstrate diversity gains, coding gains and rates of turbo space-time codes with TVLT.
In this paper we study Low Density Party Check (LDPC) codes used in the IEEE 802.16 physical layer standard. We introduce two novel techniques to enhance the performance of such codes. In the first technique, we use t...
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ISBN:
(纸本)9781424403523
In this paper we study Low Density Party Check (LDPC) codes used in the IEEE 802.16 physical layer standard. We introduce two novel techniques to enhance the performance of such codes. In the first technique, we use the binary parity check matrix proposed in the IEEE 802.16 standard, and propose a novel parity check matrix for LDPC codes over GF(4) with the non-zero entries chosen to maximize the entropy. We show that our proposed code outperforms the binary code proposed in the IEEE 802.16 standard over both AWGN and SUI-3 channel model. In our second technique, we use a high rate LDPC code, in a concatenated coding structure, as an outer code, with a convolutional code as an inner code. We compare the performance of such a concatenated code with the commonly used one utilizing Reed-Solomon codes over the standard SUI-3 channel model, and show better performance.
Error floor behavior of low-density parity-check (LDPC) codes using quantized decoding algorithms is statistically studied with experimental results on a hardware evaluation platform. The results present the distribut...
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ISBN:
(纸本)9780819469601
Error floor behavior of low-density parity-check (LDPC) codes using quantized decoding algorithms is statistically studied with experimental results on a hardware evaluation platform. The results present the distribution of the residual errors after decoding failure and reveal that the number of residual error bits in a codeword is usually very small using quantized sum-product (SP) algorithm. Therefore, LDPC code may serve as the inner code in a concatenated coding system with a high code rate outer code and thus an ultra low error floor can be achieved. This conclusion is also verified by the experimental results.
A list Viterbi algorithm (LVA) finds the n most likely paths in a trellis diagram of a convolutional code. One of the most efficient LVAs is the tree-trellis algorithm of Soong and Huang. We propose a new implementati...
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A list Viterbi algorithm (LVA) finds the n most likely paths in a trellis diagram of a convolutional code. One of the most efficient LVAs is the tree-trellis algorithm of Soong and Huang. We propose a new implementation of this algorithm. Instead of storing the candidate paths in a single list sorted according to the metrics of the paths, we show that it is computationally more efficient to use several unsorted lists, where all paths of the same list have the same metric. For an arbitrary integer bit metric, both the time and space complexity of our implementation are linear in n. Experimental results for a binary symmetric channel and an additive white Gaussian noise channel show that our implementation is much faster than all previous LVAs.
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