This work proposes a general equation for the channel reliability (L-c) of turbo code in DS/CDMA systems under flat fading channels and multiple access interference. The proposed reliability equation is suitable for p...
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This work proposes a general equation for the channel reliability (L-c) of turbo code in DS/CDMA systems under flat fading channels and multiple access interference. The proposed reliability equation is suitable for prediction under low, medium as well high signal-noise ratio (SNR) operation system. The channel reliability equation was established as a function of system loading and SNR from fitting of Monte-Carlo simulation (MCS) performance results.
We consider turbo-coded frequency-hopped systems operating in partial-band interference and fading channels under conditions which make Signal-to-Noise Ratio (SNR) estimation difficult or infeasible. For Non-Coherent ...
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We consider turbo-coded frequency-hopped systems operating in partial-band interference and fading channels under conditions which make Signal-to-Noise Ratio (SNR) estimation difficult or infeasible. For Non-Coherent Binary Frequency Shift Keying (NCBFSK) we propose blind decoder metrics that offer significant performance gains over the conventional self-normalized metric originally proposed for non-fading channels and uncoded communications. We also propose several blind heuristic metrics for phase-compensated Binary Phase Shift Keying (BPSK) systems of varying complexity and performance. For both NCBFSK and CBPSK we then derive the exact conditional LLR given the second-order averages of the interference and noise, which we refer to as semi-blind metrics. Impressive performance gains are realized in both cases. For BPSK the best totally blind heuristic metric nearly achieves the performance of the exact conditional LLR and has the advantage of not requiring any statistics on interference or noise. In all cases the performance gains are most pronounced for small values of the interference duty factor.
The effects of the channel reliability factor on the performance of turbo decoders that use a maximum a posteriori probability algorithm are investigated for wireless communication fading channels, such as Bluetooth s...
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The effects of the channel reliability factor on the performance of turbo decoders that use a maximum a posteriori probability algorithm are investigated for wireless communication fading channels, such as Bluetooth systems. The channel reliability factor is related to the channel signal-to-noise ratio. For various values of the channel reliability factor, the obtained performance curves of the maximum a posteriori probability algorithm are given for the case of DMx Bluetooth data packets. When the channel reliability factor increases, the bit-error-rate performance of the DMx Bluetooth data packets also increases over fading channels.
An implementation of the turbo coding technique for data error detection and correction in data transmission is presented. The turbo coding technique is known to be efficient in data transmission adding redundant pari...
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ISBN:
(纸本)9783642167607
An implementation of the turbo coding technique for data error detection and correction in data transmission is presented. The turbo coding technique is known to be efficient in data transmission adding redundant parity that provides a high error correction capacity decreasing the number of erroneous bits for low signal to noise ratios increasing the number of iterations. The turbo encoder and turbo decoder were implemented in a FPGA development system. The design is oriented to reach a transmission speed near to the theoretical Shannon's capacity of the communication channel and minimum possible energy consumption using only the FPGA resources without external memories.
In this paper, we investigate the performance of iterative decoding for concatenated turbo coded and Space-time block coded (STBC) system. In our proposed system the soft parity bit needs to be estimated, which differ...
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ISBN:
(纸本)9781424477425
In this paper, we investigate the performance of iterative decoding for concatenated turbo coded and Space-time block coded (STBC) system. In our proposed system the soft parity bit needs to be estimated, which differs from traditional turbo decoding, as the receiver adopts iterative decoding not only to turbo codes but the entire system. In this case a simplified and effective method of parity bit estimation is presented, which we focus on, resulting in a moderate increase of complexity. Simulation results demonstrate that performance improvement can be obtained using the iterative scheme. Meanwhile the increase of complexity caused by iteration and parity bit estimation in exchange for performance improvement is considered. Our proposed scheme makes an optimal trade-off between complexity and performance for transmitting in Rayleigh fading channel.
In this paper, we study the performance of the channel estimation in a turbo coded, orthogonal frequency division multiplexing (OFDM) with multiple antennas at the receiver. We survey the accuracy of the channel estim...
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ISBN:
(纸本)9780769539607
In this paper, we study the performance of the channel estimation in a turbo coded, orthogonal frequency division multiplexing (OFDM) with multiple antennas at the receiver. We survey the accuracy of the channel estimation for different number of users and different number of pilot subcarriers. Moreover, since there is not a closed form solution to the BER of the turbo coded system for different number of constellation size. We develop an equation to obtain the BER bound of the turbo coded OFDM/SDMA system with M-ary quadrature amplitude modulation (MQAM) in the Rayleigh flat fading channel as a function of the signal constellation and characteristic of the turbo code with a curve fitting and then propose a method for selecting switching threshold in adaptive modulation case.
Whilst the laboratory works at faculties providing education on the field of electronics and communication support the technical knowledge of students, they also develop their implementation abilities. The fact that t...
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Whilst the laboratory works at faculties providing education on the field of electronics and communication support the technical knowledge of students, they also develop their implementation abilities. The fact that there is less equipment requiring advanced technologies in laboratories, enforces the students to group works and thus limits working time and their contribution to the experiments. Contemporary computer technology provides the possibility for establishing alternative laboratories, environments in which the students can perform implementations without the restrictions of location and time. In this work, real time remote accessible experiment sets are prepared regarding coding techniques with error control. It is provided that the students can connect to the web based laboratory system via any computer on the LAN and make experiments. In this laboratory, the student will perform real time implementations without the restriction of location and time and strengthen their theoretical knowledge.
The design of asource-controlled turbo coding scheme for the transmission of strongly nonuniform binary memoryless sources over additive white Gaussian noise (AWGN) channels is considered. The use of non-binary signal...
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The design of asource-controlled turbo coding scheme for the transmission of strongly nonuniform binary memoryless sources over additive white Gaussian noise (AWGN) channels is considered. The use of non-binary signaling allows performance improvements over previous existing schemes that use binary modulation. The basic idea is to allocate more energy to the transmitted symbols associated with the information bits that occur less likely and to exploit the source nonuniformity in the decoding process. If the source and channel parameters are unknown, they can be estimated jointly with the encoding/decoding process. No performance degradation is observed in this case.
This paper investigates the unequal error protected (UEP) transmission of scalable H.264 bitstreams with two-priority layers, where differentiated turbo coding provides better protection for the high priority (HP) bas...
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This paper investigates the unequal error protected (UEP) transmission of scalable H.264 bitstreams with two-priority layers, where differentiated turbo coding provides better protection for the high priority (HP) base layer than for the low priority (LP) enhancement layer. The drawback of such a method is the high overhead introduced by the channel coding, which results in a low source data rate for the HP layer, and hence lowers video quality. To overcome this problem, we introduce an efficient combination of turbo coding and hierarchical quadrature amplitude modulation (HQAM) to provide a high protection for the HP layer and at the same time maintaining the requisite channel coding redundancy. Simulation results show that, over a wide range of channel signal-to-noise ratio (SNR), our combined technique is superior to non-scalable transmission and outperforms UEP with turbo coding alone. (C) 2006 Elsevier B.V. All rights reserved.
In this paper, a generalized multiple-input multiple-output (MIMO) antenna system that can be fitted to the uplink of a wireless communication system is considered for the general case of multi-user. At the transmitte...
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In this paper, a generalized multiple-input multiple-output (MIMO) antenna system that can be fitted to the uplink of a wireless communication system is considered for the general case of multi-user. At the transmitter, the information bits are turbo coded, then interleaved and passed through a serial-to-parallel converter. The channel is assumed bad urban suffering from multipath Rayleigh fading resulting in inter-symbol and multiple access interferences (ISI and MAI). At the front-end of the receiver, a number of receiving antennas are used followed by a joint multi-user estimator based on the Minimum Mean Square Error Block Linear Equalizer (MMSE-BLE). Computer simulations demonstrate a significant performance improvement in both single user and multi-user cases.
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