Burst packet loss is a common problem over wired and wireless networks and leads to a significant reduction in the performance of packet-level forward error correction (FEC) schemes used to recover packet losses durin...
详细信息
Burst packet loss is a common problem over wired and wireless networks and leads to a significant reduction in the performance of packet-level forward error correction (FEC) schemes used to recover packet losses during transmission. Traditional FEC interleaving methods adopt the sequential coding-interleaved transmission (SCIT) process to encode the FEC packets sequentially and reorder the packet transmission sequence. Consequently, the burst loss effect can be mitigated at the expense of an increased end-to-end delay. Alternatively, the reversed interleaving scheme, namely, interleaved coding-sequential transmission (ICST), performs FEC coding in an interleaved manner and transmits the packets sequentially based on their generation order in the application. In this study, the analytical FEC model is constructed to evaluate the performance of the SCIT and ICST schemes. From the analysis results, it can be observed that the interleaving delay of ICST FEC is reduced by transmitting the source packets immediately as they arrive from the application. Accordingly, an Enhanced ICST scheme is further proposed to trade the saved interleaving time for a greater interleaving capacity, and the corresponding packet loss rate can be minimized under a given delay constraint. The simulation results show that the Enhanced ICST scheme achieves a lower packet loss rate and a higher peak signal-to-noise-ratio than the traditional SCIT and ICST schemes for video streaming applications.
Over the last two decades there has been increasing interest in a free-space optical communication (FSO) as a backup or alternative to radio frequency communication. The main disadvantage of FSO through the atmosphere...
详细信息
ISBN:
(纸本)9781509021529
Over the last two decades there has been increasing interest in a free-space optical communication (FSO) as a backup or alternative to radio frequency communication. The main disadvantage of FSO through the atmosphere is related to time-varying turbulence-induced changes in the channel. Theoretical coding error performance analysis of such channels is challenging due to the complicated multidimensional integration that is required. In this paper, the coding error performance is analyzed using simulations with a recent non-memoryless optical channel simulator. The simulation results confirm theoretical analysis and show almost negligible influence of the channel memory on coding performance.
Reed-Solomon (RS) codes are commonly utilized in magnetic recording systems to correct error bursts. A soft-output Viterbi algorithm (SOVA) is a commonly used detector to provide soft information to error-correcting d...
详细信息
Reed-Solomon (RS) codes are commonly utilized in magnetic recording systems to correct error bursts. A soft-output Viterbi algorithm (SOVA) is a commonly used detector to provide soft information to error-correcting decoders. We propose a novel architecture of a multilevel interleaved RS coding scheme that not only provides better performance but also has less complexity than an equivalent RS code. This architecture implements an error event detector using the soft information generated by the SOVA detector. The performance and complexity of the decoding technique are compared with the well-known soft-decoding techniques, such as generalized minimum distance decoding and Chase decoding techniques.
The performance of a time-division multiple-access mobile radio system adopting slow frequency hopping is analyzed by following an original procedure that allows the evaluation of thermal noise and fast fading (e.g., ...
详细信息
The performance of a time-division multiple-access mobile radio system adopting slow frequency hopping is analyzed by following an original procedure that allows the evaluation of thermal noise and fast fading (e.g., Rayleigh) effects on block-coded transmission with nonideal interleaving. Starting from this approach, service coverage can be analytically evaluated when the "slow" disturbances affecting the transmission are fixed. The method proposed is able to take several impairments and parameters into account, such as shadowing and discontinuous transmission. The experimental results confirmed the validity of the theoretical approach.
We estimate the capacity of optical links at telecom wavelengths built upon existing terrestrial technologies. We study the impact of molecular absorption while varying the modulation scheme and compare the result wit...
详细信息
We estimate the capacity of optical links at telecom wavelengths built upon existing terrestrial technologies. We study the impact of molecular absorption while varying the modulation scheme and compare the result with the ultimate capacity achievable in void. We then investigate the impact of atmospheric turbulence and evaluate how much capacity we recover with current mitigation techniques such as adaptive optics, and data coding coupled with delay diversity or data interleaving. We conclude by evaluating the achievable capacity in the presence of molecular absorption and atmospheric turbulence.
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...
详细信息
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.
This paper describes techniques for the design and analysis of trellis codes that provide reliable communication over every channel in a specified set of possible channels, where each channel is characterized by addit...
详细信息
This paper describes techniques for the design and analysis of trellis codes that provide reliable communication over every channel in a specified set of possible channels, where each channel is characterized by additive white Gaussian noise with a distinct periodic variation in signal-to-noise ratio. An important practical application for such trellis codes is the periodic erasure channel produced by partial-band interference dispersed by a block interleaver. We present trellis codes that provide reliable communication over all periodic erasure patterns of a given period for which the number of unerased coded bits per period is at least equal to the number of information bits per period.
A soft-decision 8-DPSK modulation format is introduced in a concatenated coding scheme and the performance of the resulting system is evaluated over a slow Rayleigh fading HF ionospheric Link in the presence of Additi...
详细信息
A soft-decision 8-DPSK modulation format is introduced in a concatenated coding scheme and the performance of the resulting system is evaluated over a slow Rayleigh fading HF ionospheric Link in the presence of Additive White Gaussian noise (AWGN). Well-known Ungerboeck TCM techniques are used as inner codes and a Reed-Solomon block code as outer code. The coded/modulated signal is differentially encoded before transmission to combat random phase changes caused by the channel. Soft-decision demodulator's output is used as an input to a modified Viterbi decoder that calculates the Euclidean distances of the received signal from an 8-PSK constellation adapted to the signal's amplitude variations. Block interleaving techniques are necessary to randomise long bursts of errors caused by the fading channel. Simulation results show that significant coding gains are achieved with a minor bandwidth expansion over uncoded, diversity or other coded systems. Finally, the interesting effects of interleaving on the performance of the proposed systems are analysed.
In this paper the performance of a concatenated coding scheme is evaluated over a slow Rayleigh fading HF ionospheric link with additive white Gaussian noise (AWGN). Well-known Ungerboeck TCM techniques onto an 8-PSK ...
详细信息
In this paper the performance of a concatenated coding scheme is evaluated over a slow Rayleigh fading HF ionospheric link with additive white Gaussian noise (AWGN). Well-known Ungerboeck TCM techniques onto an 8-PSK signal set are used as inner codes and Reed-Solomon block codes as outer codes. The coded/modulated signal is further differentially encoded before transmission to combat random phase changes. Block interleaving techniques are necessary to randomise long bursts of errors caused by the fading channel. The performance of the proposed concatenated coding system is investigated for various Doppler spreads. Significant coding gains are achieved over uncoded, diversity or other conventionally coded systems with a small bandwidth expansion. Finally the interesting effects of interleaving on the behaviour of the proposed systems are analysed. Copyright (C) 2001 John Wiley & Sons, Ltd.
The achievable rate of a coherent coded modulation digital communication system with data-aided channel estimation and a discrete equiprobable symbol alphabet is derived under the assumption that the system operates o...
详细信息
The achievable rate of a coherent coded modulation digital communication system with data-aided channel estimation and a discrete equiprobable symbol alphabet is derived under the assumption that the system operates on a flat fading multiple-input/multiple-output channel and uses a perfect interleaver to combat the bursty nature of the channel. It is shown that linear minimum mean square error channel estimation directly follows from the derivation and links average mutual information to the channel dynamics. Based on the assumption that known training symbols are transmitted, the achievable rate of the system is optimized with respect to the amount of training information needed.
暂无评论