In this paper, ultra-wideband (UWB) multiple access systems are introduced by using direct-sequence (DS) and hybrid directsequence time-hopping (DS/TH) code division multiple access (CDMA) that use arbitrary chip-duty of the spreading sequences. The bit error probabilities are presented. First of all, the variances of the multiple access interference are developed by investigating the collision...

In this paper, we propose and analyze concatenated coding schemes for direct-sequence code-division multiple-access (DS/CDMA) systems in asynchronous channels. In the concatenated coding, bandwidth-efficient 2 -state L/(L+1)-rate 2MTCM with biorthogonal signal constellation is used for the inner code, and (2 1, d(2 1)/L/2e) RS code is used for the outer code. It is shown that we can get conside...

A new joint detection method based on sphere packing lattice decoding is presented in this paper. The algorithm is suitable for both synchronous and asynchronous multiple access direct-sequence code-division multiple-access (DS-CDMA) systems, and it may jointly detect up to 64 users with a reasonable complexity. The detection complexity is independent of the modulation size and large -PAM or -Q...

In this paper, we propose and analyze a multiuser receiver using a decorrelating filter and Viterbi decoders for trellis-coded direct-sequence code-division multiple-access (DS/CDMA) systems with biorthogonal signal constellation in asynchronous channels. The biorthogonality is implemented by user signature waveforms and the decorrelating filter. The performance of the proposed system is invest...

Conventional asynchronous control circuit design is complex because potential designs must be analysed for the existence of hazards and state variable races, as these may cause incorrect circuit operation. We present the innovative CMOS direct-mapped asynchronous circuit design approach, which, by defining a one-to-one mapping between state diagram and CMOS circuit implementation, removes the n...

Asynchronous circuits are increasingly proposed as an efficient circuit-level solution for Process Variability. Asynchronous circuits are self timed, which gives them the opportunity to be immune against all variability sources including process-variability. Moreover, asynchronous circuits gain interesting properties due to variability in terms of performance and power-consumption distribution....

This paper deals with optical packet switches with limited buffer capabilities, subject to asynchronous, variable-length packets and connection-oriented operation. The focus is put on buffer scheduling policies and queuing performance evaluation. In particular a combined use of the wavelength and time domain is exploited in order to obtain contention resolution algorithms that guarantee the seq...

It is very important, to optimize of clean electrical energy by employing of variable Speed pumped storage power plant (VSPSP). Variable speed machines are used extensively in wind power plants and pumped storage power plants. Therefore, the advantages of this technology are including: stability, reliability, fast dynamic responses, frequency control and high efficiency of power system. By usin...