A new class of Latin square, a uniform Latin square, as an interleaving algorithm has been introduced to correct two-dimensional (2-D) burst errors in data-storage systems. The uniform Latin square with order n = l (....
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ISBN:
(纸本)0780390091
A new class of Latin square, a uniform Latin square, as an interleaving algorithm has been introduced to correct two-dimensional (2-D) burst errors in data-storage systems. The uniform Latin square with order n = l (.) m guarantees that there are no duplicated numbers in any (l - 1) x m or l x (m - 1) areas in an n x n square. Uniform Latin square interleaving has twice the error-correcting ability of the interleaving of a conventional Latin square for large 2-D burst errors.
Reed-Solomon (RS) codes are commonly utilized in magnetic recording systems to correct error bursts. Soft-output Viterbi algorithm (SOYA) is a commonly used detector to provide soft information to error-correcting dec...
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ISBN:
(纸本)9781479923588
Reed-Solomon (RS) codes are commonly utilized in magnetic recording systems to correct error bursts. Soft-output Viterbi algorithm (SOYA) is a commonly used detector to provide soft information to error-correcting decoders. We propose a novel architecture of 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 SOYA detector.
We consider the estimation of Viterbi decoder performance for convolutional codes with interleaving over fading channels subject to practical power control algorithms. Given a received vector of (time-varying) E/sub b...
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We consider the estimation of Viterbi decoder performance for convolutional codes with interleaving over fading channels subject to practical power control algorithms. Given a received vector of (time-varying) E/sub b//N/sub 0/ values for a frame, we compute the error probability and effective E/sub b//N/sub 0/ for that frame, where the latter is defined as the E/sub b//N/sub 0/ on an AWGN channel that results in the same frame error rate. We validate our analysis using the R=1/3 convolutional code and interleaver used on the IS-95 CDMA reverse channel.
In addition to diversity, forward error correction (FEC) coding is a well-known method that can be used to improve the performance of communication on wireless fading channels. In this paper, we investigate the perfor...
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In addition to diversity, forward error correction (FEC) coding is a well-known method that can be used to improve the performance of communication on wireless fading channels. In this paper, we investigate the performance of combined diversity and FEC coding strategies. For block coding to be effective, bit errors in each code word should be independent. To render the channel memoryless, perfect bit interleaving is assumed. That is, bit errors in the code word are assumed to be independent. In this paper, we analyze the performance of M-ary differential phase shift keying (MDPSK) on frequency-selective Rayleigh fading channels using two branch postdetection equal gain (EG) combining. Both the effects of correlation between the two diversity branches and the effects of cochannel interference on the BER performance are investigated. The interferers are assumed to be MDPSK modulated signals with same symbol rate as that of the desired signal, but with random symbol timing offsets relative to the desired signal. The cochannel interference contribution is represented by a Gaussian noise whose mean and variance are equal to the mean and variance of the sum of the interfering signals.< >
It was shown earlier that the combination of bit interleaved coded modulation (BICM) with space time block codes (STBC) for OFDM systems leads to the maximum diversity order in space and frequency. In this paper we pr...
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It was shown earlier that the combination of bit interleaved coded modulation (BICM) with space time block codes (STBC) for OFDM systems leads to the maximum diversity order in space and frequency. In this paper we present low complexity decoding of BICM-STBC systems. First, the maximum likelihood (ML) bit metric calculations are simplified from a distance on the complex plane to a distance on the real line. Furthermore, we present log-likelihood-ratio (LLR) approximations to maximum likelihood (ML) decoding metrics to achieve easier to implement soft decision bit metrics with the same high performance. The LLR bit metrics are specifically calculated for M-ary QAM signal constellations used in IEEE 802.11a/g networks. Simulation results also show that while achieving a substantial improvement in decoder complexity, the proposed bit metrics achieve the same high performance.
The burst errors experienced on coded satellite links impact the operation of both asynchronous transfer mode (ATM) and ATM adaptation layer (AAL) protocols and their transport in synchronous digital hierarchy/plesioc...
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The burst errors experienced on coded satellite links impact the operation of both asynchronous transfer mode (ATM) and ATM adaptation layer (AAL) protocols and their transport in synchronous digital hierarchy/plesiochronous digital hierarchy (SDH/PDH) frames. COMSAT has developed an ATM link enhancer (ALE), which provides significant improvement in the probability of cell discard due to header errors, improves loss of frame performance when using the physical layer convergence protocol (PLCP) in PDH, and reduces certain errors experienced in AAL type 1 and AAL type 3/4. This paper describes the DS-3 hardware implementation of the ALE, including the techniques used to establish and maintain the PLCP and deinterleaver frame synchronization, perform selective interleaving/deinterleaving of ATM cells, and perform header error correction on deinterleaved cells. In addition, it provides a functional description of the ALE and the prototype ALE hardware implementation. The paper summarizes the measured ALE performance in a satellite field trial, and compares its measured and predicted performance using data collected via the field trial.< >
A direct-sequences code division multiple access system has been accepted as a digital cellular standard (IS-95) in North America. This digital cellular standard employs a powerful rate 1/2, constraint length 9, convo...
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A direct-sequences code division multiple access system has been accepted as a digital cellular standard (IS-95) in North America. This digital cellular standard employs a powerful rate 1/2, constraint length 9, convolutional code in its forward link. It is well-known that in a Rayleigh fading channel the performance of a channel code depends very heavily on the interleaving depth and the relative variations of the channel characteristics. In slow fading channels, since the input symbols to the channel decoder are highly correlated, the bit-error-rate at the output of the channel decoder may be unacceptably high. Interleavers of large dimensions can reduce the correlation of the input signal to the channel decoder at the expense of an intolerable delay. In this paper we examine the performance of the IS-95 system, at the mobile receiver, for different channel fade rates.
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