Discusses how in an automatic, adaptive HF system with errorcorrection, RF power output levels around 400W will provide good results. To enhance the reliability and throughput of the link, especially over the shorter...
详细信息
Discusses how in an automatic, adaptive HF system with errorcorrection, RF power output levels around 400W will provide good results. To enhance the reliability and throughput of the link, especially over the shorter distances, the allocated frequencies should include the 'odd' bands (the high bands that were not listed as useable in the traditional predictions). Further studies of sporadic E reflections will be required. The present analysis of existing test plots shows that the full potential of these reflections has not been utilized. The analysis of the test results are notable in another respect. The residual character error-rate is <10-6 for the short links, and approximately=10-5 for the longer. This difference indicates that there is room for further investigation and improvements in the error-correcting methods or algorithms.< >
The finite field is widely used in error-correcting codes and cryptography. Among its important arithmetic operations, multiplication is identified as the most important and complicated. Therefore, a multiplier with c...
详细信息
The finite field is widely used in error-correcting codes and cryptography. Among its important arithmetic operations, multiplication is identified as the most important and complicated. Therefore, a multiplier with concurrent error detection ability is elegantly needed. In this paper, a concurrent error detection scheme is presented for bit-parallel systolic dual basis multiplier over GF(2 m ). The proposed multiplier takes only one extra clock cycle while traditional multipliers using XOR trees consume at least extra XOR gate delays in GF(2 m ) fields. Our analysis shows that all single stuck-at faults can be detected concurrently
A new soft decision decoding algorithm for convolutional codes is introduced. It has been shown that the decoder complexity is reduced substantially in comparison with conventional Viterbi decoder. The particular appl...
详细信息
A new soft decision decoding algorithm for convolutional codes is introduced. It has been shown that the decoder complexity is reduced substantially in comparison with conventional Viterbi decoder. The particular application studied is a trellis coded 4-PSK modulation.< >
Presents a new algorithm for estimating parameters in a 2-binary symmetric channel-state hidden Markov model for the HF radio channel, based on a 2D optimisation by binary search of "bad" state parameters. E...
详细信息
Presents a new algorithm for estimating parameters in a 2-binary symmetric channel-state hidden Markov model for the HF radio channel, based on a 2D optimisation by binary search of "bad" state parameters. Excellent modelling accuracy has been obtained, as shown by close fits between distributions of various error statistics for actual and simulated data. The performance of the multiple transmission scheme without FEC and without adaptivity is not impressive. FEC alone and adaptivity alone offer some advantages, but these seem too small to justify the increase in complexity. The best performance is obtained when both FEC and adaptivity are employed: with triple-errorcorrection, single-repetition in the "good" state and triple-repetition in the "bad" state, a respectable block throughput of 0.69 (bit throughput of 0.36) is achieved.< >
In many practical applications (eg. time varying channels, adaptive communication systems), it is useful to measure the signal-to-noise ratio (SNR) of the channel. The known algorithms require a sufficient amount of c...
详细信息
In many practical applications (eg. time varying channels, adaptive communication systems), it is useful to measure the signal-to-noise ratio (SNR) of the channel. The known algorithms require a sufficient amount of computer calculations and a very large number of received symbols must be examined before a statistically reliable SNR estimate can be made. The authors introduce two new techniques for SNR measurement using trellis structure. To do this, two metric values at the output of the trellis decoder are defined. These metrics are derived from the original decoding processes by subtracting the confidence of the greatest likelihood path from that of the next greatest likelihood path, and/or the one with minimum likelihood path.< >
An approach to fault-tolerant computing in general and digital signal processing in particular is that of arithmetic error-detecting/correcting codes. These codes were designed to commute with the addition operator an...
详细信息
An approach to fault-tolerant computing in general and digital signal processing in particular is that of arithmetic error-detecting/correcting codes. These codes were designed to commute with the addition operator and the theory is extensive. In digital signal processing applications the bulk of the arithmetic is addition and multiplication, it is therefore interesting to look for codes that commute with both addition and multiplication. It is shown that such a code does in fact exist; an AN code where the code generator A is an idempotent i.e. A/sup 2/=A. This code, unfortunately, has a serious deficiency in that errors can be masked by a fault-free multiplier. Thus no single (non-separate) code is suitable for both addition and multiplication. Motivated by this problem and the fact that AN codes were designed around the addition operator, the characteristics of a code that commutes with multiplication are discussed. A simple code that satisfies these requirements is presented: an AN+B code. The results of some computer simulations of an AN+B coded multiplier are given.< >
The behaviour of a concatenated coding scheme using TCM on the 8-DPSK signal set as inner codes and RS outer codes is investigated over a slow Rayleigh fading and AWGN channel. It is shown that TCM schemes alone can n...
详细信息
The behaviour of a concatenated coding scheme using TCM on the 8-DPSK signal set as inner codes and RS outer codes is investigated over a slow Rayleigh fading and AWGN channel. It is shown that TCM schemes alone can not provide a satisfactory performance but concatenated systems can give acceptable performance using burst error-correcting outer codes in parallel with interleaving techniques with a loss of 1/8-1/4 bits/sec/Hz. The resulting systems seem to be powerful tools that can effectively operate on heavily distorted HF ionospheric links.< >
High demand for an increase of packing density still lends motivation to the development of new robust recording codes. The study of ternary codes with charge-constraint is one of the interesting practical approaches ...
详细信息
High demand for an increase of packing density still lends motivation to the development of new robust recording codes. The study of ternary codes with charge-constraint is one of the interesting practical approaches for this purpose. Given bounds on the run-length and the accumulated charge under NRZL rule, the authors investigate the channel capacity of ordinary ternary recording codes. The results are tabulated.< >
The application of error control to long-haul optically amplified lightwave systems is considered. Some prospective coding schemes are noted and their performance is assessed analytically. A coding scheme of much redu...
详细信息
The application of error control to long-haul optically amplified lightwave systems is considered. Some prospective coding schemes are noted and their performance is assessed analytically. A coding scheme of much reduced complexity compared with currently proposed arrangements is identified and shown to offer comparable performance at the relevant channel error rates.< >
The possibility of applying MECLCs (M-ary error correcting line codes) in conjunction with SSB transmission and linear modulation schemes is examined. Such schemes are considered to be potentially of interest for futu...
详细信息
The possibility of applying MECLCs (M-ary error correcting line codes) in conjunction with SSB transmission and linear modulation schemes is examined. Such schemes are considered to be potentially of interest for future personal communication systems. A new class of error correcting codes with defined spectra was introduced; such codes provide error control as well as a null at DC and suppressed low frequency spectrum. Comparisons with traditional systems that employ line coding and error control coding in cascade reveal that the new schemes not only have better spectral characteristics but also significantly improved error performance without incurring any penalty in increased complexity. Indeed they are generally less complex since the error control power required is significantly reduced. MECLCs therefore offer high efficiency and improved error performance.< >
暂无评论