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Proposed is a zero-inserting precoder and a two-stage linear equaliser, to shorten the guard interval in block-based single-carrier modulation. The first-stage equaliser consists of a linear single-tapper-subcarrier frequency-domain equaliser. The second-stage equaliser maximises the SINR, in the time-domain, based on the interference-plus-noise estimated from the zero-padded sub-intervals of the single-carrier modulation. This proposed scheme is applicable even without cyclic prefixing.

SUMMARYWe propose that the throughput performance of the DS CDMA unslotted ALOHA system with two user classes is analyzed by the M/M/infinity queueing model without the death rate approximation. The previous scheme uses the M/D/infinity queueing model with the death rate approximation. The new analysis method is simpler than the previous one because four-dimensional summation is replaced by two-dimensional summation in the packet success probability calculation. The speed of new analysis program is 250 times faster than that of the previous one. In the numerical results, we consider the cases when the message arrival rates of the two classes are equal or not equal, and the access control is present or not. It shows that the proposed scheme has more accurate analyzed throughput than the previous one does.

It has been known that communication systems are susceptible to strong impulsive noises. To combat this, convolutional coding has long served as a cost-effective tool in the context of moderately frequent occurrence of memoryless impulses with given statistics. Nevertheless, the impulsive noise statistics is hard to be accurately modeled and is generally not time-invariant, making the respective system design challenging. In this article, in the absence of full knowledge of the probability density function (PDF) of impulsive noises, we devise an efficient decoding scheme for single-carrier narrowband communication systems by incorporating a design parameter into the recently introduced joint erasure marking and This is the Pre-Published Version 2 Viterbi decoding algorithm, dubbed the metric erasure Viterbi algorithm (MEVA). The proposed scheme is equivalent to incorporating a well-designed clipping operation into the Viterbi algorithm, of which the clipping threshold has to be appropriately set. In contrast with existing publications that often resort to extensive simulations, we characterize the bit error probability performance associated with the clipping threshold by deriving its Chernoff bound. Simulation results reveal that with a judicious selection of the clipping threshold, the MEVA can be on par with its optimal maximum-likelihood decoding counterpart under fairly general circumstances.

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