Error correcting codes such as turbo codes are incorporated in present-day wireless and satellite communication systems for error free data transmission. Conventional turbo decoders use the map algorithm to achieve ne...
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ISBN:
(纸本)9781665473507
Error correcting codes such as turbo codes are incorporated in present-day wireless and satellite communication systems for error free data transmission. Conventional turbo decoders use the map algorithm to achieve near Shannon limit performance. Many hardware implementations of turbo decoders are carried out on FPGAs. But there is inefficiency in the realization of such complex designs with respect to area and power compared to that of ASICs. This work highlights the realization of a turbo decoder on coarse grained reconfigurable architectures (CGRAs)- a new class of programmable hardware that amalgamates the advantages of both ASICs and FPGAs. For the modelling, exploration and implementation of such architectures, hardware designers have developed many platforms. In this work,the realization of complex iterative loops of turbo decoder on CGRAs, are carried out using CGRA-ME framework, thus eliminating the complexity involved in its FPGA equivalent. The turbo decoder benchmark is implemented on ADRES and flavours of Simple CGRAs. The corresponding configuration bitstreams and the Verilog HDLs generated, are used to perform the area and power analysis. The decoder implemented on ADRES results in the reduction of area by 15.48% and 35.21% compared to that of Simple diagonal and Simple orthogonal respectively. The net power consumed by Simple orthogonal is less in comparison to Simple diagonal by 41.68% and with that of ADRES by 6.36%.
Dual N-ary orthogonal hybrid modulation system can increase the data rate greatly compared with conventional N-ary orthogonal spread spectrum system, so it can be used for high rate data communication. In this paper, ...
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ISBN:
(纸本)9781424414468
Dual N-ary orthogonal hybrid modulation system can increase the data rate greatly compared with conventional N-ary orthogonal spread spectrum system, so it can be used for high rate data communication. In this paper, three code recognition algorithms are presented for dual N-ary orthogonal hybrid modulation system. Then the performance of the system in AWGN and flat Rayleigh fading channel with the three different code recognition algorithms is simulated. The simulation results show that the simplified map algorithm is best for the system with a compromise between the performance and the complexity.
In this paper, a new state metric normalization technique is proposed for maximmn-a-posteriori-probability (map) algorithm to enhance the throughput of map decoder. Bite error-rate (BER) performance comparison showed ...
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ISBN:
(纸本)9781479924325;9781479926596
In this paper, a new state metric normalization technique is proposed for maximmn-a-posteriori-probability (map) algorithm to enhance the throughput of map decoder. Bite error-rate (BER) performance comparison showed that the map algorithm based on the proposed normalization technique has a coding gain of 0.25 dB at a BER of 10(-4) in comparison with map algorithm based on the subtractive normalization technique. An architecture for map decoder based on the new normalization technique has been proposed with a reduced critical path delay as compared to the contributions in literature. Subsequently, a field-programmable-gate-array (FPGA) implementation of the new map decoder is carried out. Thereby, the proposed decoder based on non-parallel radix-2 and radix-4 architectures are able to achieve high throughputs of 514 Mbps and 1.028 Gbps respectively.
In this paper, the performance of the Least Squares (LS) estimator along with turbo codes in OFDM is evaluated for the SUI channel models in the presence of AWGN. Turbo codes are used in this paper because of its BER ...
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ISBN:
(纸本)9781479925810
In this paper, the performance of the Least Squares (LS) estimator along with turbo codes in OFDM is evaluated for the SUI channel models in the presence of AWGN. Turbo codes are used in this paper because of its BER performance close to Shannon limit. The iterative turbo decoder exchanges soft information between the component decoders. Maximum A Posteriori (map) and its simplified version Max-Log-map algorithms are used for the component decoders. The performance and complexity comparison is also made between the decoding algorithms. Moreover the effect of memory order on the performance of the decoding algorithms is also studied.
Due to the rapid evolution of mobile communication systems that uses Code Division Multiple Access (CDMA), the importance of multiuser detection increased significantly. This paper aims to illustrate the performances ...
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ISBN:
(纸本)9781424463633
Due to the rapid evolution of mobile communication systems that uses Code Division Multiple Access (CDMA), the importance of multiuser detection increased significantly. This paper aims to illustrate the performances of synchronous Minimum Mean-Square Error (MMSE) multiuser detectors in presence of convolutional coding/decoding and turbo coding and decoding algorithms, in perfect and imperfect reception conditions. Extensive Monte Carlo simulations have been performed to evaluate the system performances in different conditions. The results are evaluated in terms of Bit Error Rate (BER) for different Signal-to-Noise Ratios (SNR's) and compared one another. From those results several interesting conclusions are highlighted.
Most of results in channel coding theory have been accomplished basing on the additive white Gaussian noise (AWGN) channels assumption. This hypothesis is not fulfilled in realistic environments in communications appl...
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ISBN:
(纸本)9781424443451
Most of results in channel coding theory have been accomplished basing on the additive white Gaussian noise (AWGN) channels assumption. This hypothesis is not fulfilled in realistic environments in communications applications. In this paper, we investigate the robustness of the turbo code decoding algorithm in presence of a generalized Gaussian (GG) noise. This noise model has been proposed for modeling in many applications such as audio and speech processing. The probability density function (PDF) of such model depends on a shape parameter which determines the decay rate of the distribution. This paper presents the decoding performances of turbo code in terms of bit error rate (BER) when the noise PDF departs from Gaussianity into a GG distribution.
This paper proposes a new and modified map algorithm for double binary convolutional turbo code (DB CTC) based on a new definition of branch metrics. The exponential and logarithmic operations in the convolutional alg...
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ISBN:
(纸本)9781424462520
This paper proposes a new and modified map algorithm for double binary convolutional turbo code (DB CTC) based on a new definition of branch metrics. The exponential and logarithmic operations in the convolutional algorithm are not needed in the iterative process after a date pre-processing of the received sequence. Furthermore, computational complexity analysis of branch metrics and performance simulation are also presented to demonstrate the effectiveness of our modified algorithm.
Due to high error correcting capability turbo coding is highly used in digital communication systems. In this article a new design of turbo decoder with reduced dynamic power dissipation is presented. In this modified...
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ISBN:
(纸本)9781467389624
Due to high error correcting capability turbo coding is highly used in digital communication systems. In this article a new design of turbo decoder with reduced dynamic power dissipation is presented. In this modified decoder, standard cell based design using pipeline logarithm-maximum a posterior (Log-map) algorithm with clock gating and variable number of iteration is used to reduce the area and to increase the throughput. The information rate of 100 Mbps will be bolstered by forthcoming 3G Long Term Evolution (LTE) standards. In 20 MHZ of transfer speed, this information rate will be accomplished. For the entry of high information rate of the 3G LTE frameworks, there is a key prerequisite of turbo decoder execution. In this work, Log-map computation based turbo decoder for LTE beneficiary is proposed. The Log-map established turbo decoder gives execution closer as far as possible with sensible computational unpredictability. The VHDL coding for parallel design of turbo decoder utilizing Log-map calculation for LTE is recreated and combined utilizing Xilinx14.2, Spartan 3 family and the outcomes are checked with the manual count.
This paper investigates the performance of a turbo-coded system transmitted over AWGN channels using quaternary partial response Continuous Phase Modulation (CPM). The system provides an attractive option for spectral...
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ISBN:
(纸本)0780385497
This paper investigates the performance of a turbo-coded system transmitted over AWGN channels using quaternary partial response Continuous Phase Modulation (CPM). The system provides an attractive option for spectral efficient communications systems. We compare the performances of a Maximum A Posteriori (map) algorithm and a Soft Output Viterbi algorithm (SOVA). The paper considers the hybrid concatenation of a parallel designed turbo encoder and a partial response quaternary CPM modulator. Based on the decomposition theory of CPM, the quaternary CPM modulator is decomposed into a ring Continuous Phase Encoder (CPE) and a Memoryless Modulator (MM). This allows a quaternary convolutional encoder to be combined with the CPE without the need of a mapper. The hybrid design combined with iterative decoding yield very good performances. The results show the considerable superiority of the map algorithm to that of the SOVA.
This paper investigates the performance of a turbo-coded system transmitted over a correlated Rician flat fading channel using quaternary partial response Continuous Phase Modulation (CPM). The system provides an attr...
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ISBN:
(纸本)0780385217
This paper investigates the performance of a turbo-coded system transmitted over a correlated Rician flat fading channel using quaternary partial response Continuous Phase Modulation (CPM). The system provides an attractive option for spectral efficient communications systems. We compare the performances of a Maximum A Posteriori (map) algorithm and a Soft Output Viterbi algorithm (SOVA). The paper considers the hybrid concatenation of a parallel designed turbo encoder and a partial response quaternary CPM modulator. Based on the decomposition theory of CPM, the quaternary CPM modulator is decomposed into a quaternary ring Continuous Phase Encoder (CPE) and a Memoryless Modulator (MM). This allows a quaternary convolutional encoder to be combined with the CPE without the need of a mapper. The hybrid design combined with iterative decoding yield very good performances. The results show the considerable superiority of the map algorithm to that of the SOVA.
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