Higher data rates at lower power levels, Internet, and wireless multimedia applications are the demands of future wireless digital communication links than most of today’s systems. Today’s available wireless network...
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ISBN:
(数字)9789811082405
ISBN:
(纸本)9789811082405;9789811082399
Higher data rates at lower power levels, Internet, and wireless multimedia applications are the demands of future wireless digital communication links than most of today’s systems. Today’s available wireless network technologies due to certain limitations fail to fulfill customer requirements. This motivation directed researchers to develop more advanced and efficient technology. Orthogonal Frequency Division Multiplexing (OFDM)-based WiMAX (Worldwide Interoperability for Microwave Access) system is one of them. WiMAX is the latest last mile wireless technologies to deliver broadband access services to residential and enterprise customers in an economical way. This system is incorporated with powerful channel coding along with interleaving to achieve time diversity. This work presents design and analysis of the Bit Error Rate (BER) performance of the WiMAX baseband physical layer as per the parameters set by IEEE 802.16 standards under concatenated channel coding techniques, whereby a Reed–Solomon (RS) code is added with Convolutional coding (CC). BER analysis confirmed that RS–CC channel coding gives better noise performance of the system with minimal SNR.
This paper describes how to apply polar codes in high-throughput space *** high throughput space communications can enable terabit data rate capacity wideband wireless transmissions,and offer service availability of a...
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This paper describes how to apply polar codes in high-throughput space *** high throughput space communications can enable terabit data rate capacity wideband wireless transmissions,and offer service availability of anywhere and *** paper investigates the channel characteristics in space *** channels are lossy,time-varying,intermittent,long-latency,and with imperfect channel state information(CSI).In order to make the polar codes suitable for the space channel,some improvements and designs on the polar codes are provided in this *** encoding and decoding methods of polar codes are discussed,which are the key to determine the *** describe some rateless polar coding schemes that can guide the construction of suitable codes for time-varying channels with no-CSI in long-haul ***,a high-rate parallel concatenation scheme of polar codes is introduced,which can improve the anti-interrupt ability of polar ***,in order to support the massive connectivity requirements of future space communication networks,polar-coded sparse-code-multiple-access(SCMA)schemes are investigated.
We consider the problem of reliable communication over non-binary insertion/deletion channels where symbols are randomly deleted from or inserted in the received sequence and all symbols are corrupted by additive whit...
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We consider the problem of reliable communication over non-binary insertion/deletion channels where symbols are randomly deleted from or inserted in the received sequence and all symbols are corrupted by additive white Gaussian noise. To this end, we utilize the inherent redundancy achievable in non-binary symbol sets by first expanding the symbol set and then allocating part of the bits associated with each symbol to watermark symbols. The watermark sequence, known at the receiver, is then used by a forward-backward algorithm to provide soft information for an outer code which decodes the transmitted sequence. Through numerical results and discussions, we evaluate the performance of the proposed solution and show that it leads to significant system ability to detect and correct insertions/deletions. We also provide estimates of the maximum achievable information rates of the system, compare them with the available bounds, and construct practical codes capable of approaching these limits.
Multilevel coding (MLC) is compared with bit-interleaved coded modulation (BICM) from a performance-versus-complexity standpoint. In both approaches, complexity-optimized error-reducing low-density parity-check inner ...
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Multilevel coding (MLC) is compared with bit-interleaved coded modulation (BICM) from a performance-versus-complexity standpoint. In both approaches, complexity-optimized error-reducing low-density parity-check inner codes are designed for concatenation with an outer hard-decision code, for various modulation orders. The codes are designed to achieve various points on the Pareto frontier characterizing the performance-complexity tradeoff. Computer simulations of the resulting codes reveal that MLC not only provides significant advantages compared with BICM, but also outperforms several existing MLC and BICM proposals. At 25% overhead, MLC provides a net coding gain of up to 12.8 dB with 16-QAM (1.0 dB from the constrained Shannon limit), a net coding gain of up to 13.6 dB with 64-QAM (1.2 dB from the constrained Shannon limit), and a net coding gain of up to 14 dB with 256-QAM (1.65 dB from the constrained Shannon limit), all with reasonable decoding complexity.
The performance and design of turbo codes using coherent BPSK signaling on the Rayleigh fading channel is considered. In low signal-to-noise regions, performance analysis uses simulations of typical turbo coding syste...
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The performance and design of turbo codes using coherent BPSK signaling on the Rayleigh fading channel is considered. In low signal-to-noise regions, performance analysis uses simulations of typical turbo coding systems. For higher signal-to-noise regions beyond simulation capabilities, an average upper bound is used in which the average is over all possible interleaving schemes. Fully interleaved and exponentially correlated Rayleigh channels are explored. Furthermore, the design issues relevant to turbo codes are examined for the correlated fading channel. Turbo interleaver design criteria are developed and architectural modifications are proposed for improved performance.
In this paper, turbo codes are investigated in a slow frequency-hopped spread spectrum (FH-SS) system with partial-band jamming. In addition, full-band thermal noise is present, The channel model is that of a partial-...
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In this paper, turbo codes are investigated in a slow frequency-hopped spread spectrum (FH-SS) system with partial-band jamming. In addition, full-band thermal noise is present, The channel model is that of a partial-band jammer in which a fraction of the frequency band is jammed and the remaining fraction is unjammed, This paper focuses on the implemention and performance of a modified turbo decoder for this model, We refer to the knowledge that each transmitted bit is jammed as channel state information. We consider cases of known or unknown channel state and variable number of bits per hop. Our approach is to modify the calculation of branch transition probabilities inherent in the original turbo decoder. For the cases with no side information and multiple bits per hop, we iteratively calculate channel state estimates, Analytical bounds are derived and simulation is performed for noncoherent demodulation. The performance of turbo codes is compared with a Reed-Solomon and a concatenated code comprised of a convolutional inner code and Reed-Solomon outer code.
A novel signaling scheme is presented, where a set of orthogonal signals is transmitted in parallel. The signals are selected according to the so-called residue number system (RNS). Hence the system is essentially a m...
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A novel signaling scheme is presented, where a set of orthogonal signals is transmitted in parallel. The signals are selected according to the so-called residue number system (RNS). Hence the system is essentially a multiple code parallel communication scheme using high-modulation alphabets. It is demonstrated that the system performance van be substantially improved by exploiting a number of advantageous properties of the RNS arithmetic. The model treated in Part I, of this paper is extended here to account for the effects of the multipath Rayleigh fading channel when using noncoherent demodulation. Diversity reception techniques with equal gain combining (EGQ or selection combining (SC) are concerned. The related performance is evaluated for both nonredundant and redundant RNS-based orthogonal signaling. Interleaving and forward error-correction techniques are introduced for enhancing the system's bit error rate (BER) performance. The concept of concatenated coding-with a Reed-Solomon (RS) code as the outer code and a redundant RNS code as the inner code is presented, and the performance of the proposed concatenated code is evaluated. Expressions of the error probability for the above-mentioned scenarios are presented, and the associated BER performance is evaluated numerically with respect to specific system parameters. Without concatenated coding, coding gains up to 8.5 or 11 dB are achieved at a BER of 10(-6) using the lowest reliability dropping technique of Part I and one or two redundant moduli, respectively. The BER is substantially higher than that over the additive white Gaussian noise channel reported in Part 1. With the aid of RS coding, an additional 7.5-dB coding gain is achieved.
Hybrid automatic repeat request (ARQ) protocols have become common in many packet transmission systems due to their incorporation in various standards. Hybrid-ARQ combines the normal ARQ method with forward error corr...
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Hybrid automatic repeat request (ARQ) protocols have become common in many packet transmission systems due to their incorporation in various standards. Hybrid-ARQ combines the normal ARQ method with forward error correction (FEC) codes to increase reliability and throughput. In this paper, we look at improving upon this performance using feedback information from the destination, in particular, using a powerful FEC code in conjunction with a proposed linear feedback code for the Rayleigh block fading channels. The new hybrid-ARQ scheme is initially developed for full received packet feedback in a point-to-point link. It is then extended to various multiple-antenna scenarios [e. g., multiple-input single-output (MISO), multiple-input multiple-output (MIMO), etc.] with varying amounts of packet feedback information. Simulations illustrate gains in throughput.
In cooperative communications, error propagation at the relay nodes degrades the diversity order of the system. To combat that effect, we present a novel technique to control error propagation at the relays, which is ...
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In cooperative communications, error propagation at the relay nodes degrades the diversity order of the system. To combat that effect, we present a novel technique to control error propagation at the relays, which is implemented in the context of a distributed turbo code. In the presented technique, the relay calculates the log-likelihood ratio (LLR) values for the bits sent from the source. These values are subjected to a threshold to distinguish the reliable bits from the unreliable bits. The relay then forwards the bits that are deemed reliable and discards the bits that are not, resulting in fewer errors propagating to the destination. The assumption here is that the destination does not know the location of the discarded bits. We develop upper bounds on the end-to-end bit error rate, enabling us to optimize the threshold in terms of the minimum end-to-end bit error rate. We compare our technique with existing techniques that have been proposed to control error propagation, including using only a cyclic redundancy code check at the relay, forwarding analog LLR values, and by employing no error control at the relay at all. We demonstrate, through several numerical examples, that the proposed scheme outperforms all existing schemes.
In this paper, we consider several issues in the analysis and design of turbo-coded systems for (0, kappa) input-constrained channels. These constraints commonly arise in magnetic recording channels. This system is ch...
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In this paper, we consider several issues in the analysis and design of turbo-coded systems for (0, kappa) input-constrained channels. These constraints commonly arise in magnetic recording channels. This system is characterized by a high-rate turbo code driving a high-rate (n - l)/n, small-length (0, kappa) block code, We discuss the properties of the (0, kappa) code that affect its performance on both an additive white Gaussian noise (AWGN) and a preceded dicode channel. We address soft-in soft-out (SISO) decoding of linear and nonlinear (0, tc) codes and show that good (0, kappa) codes exist even when d(min) = 1. For the (0, tc) constrained AWGN channel, we present several rate (n - l)/n block codes that optimally tradeoff bit-error-rate performance with kappa. For the preceded dicode channel, we show that the systematic (0, n - 1) modulation codes are superior to most other rate (n - l)ln block codes in terms of error-rate performance, and their attractiveness is increased by the fact that they do not contribute any significant complexity to the overall system.
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