Sharif Digital Repository

In this paper we propose a new model for the near-far effect in a CDMA system. We derive upper and lower bounds for the maximum near-far effect for errorless transmission. Using these bounds, we propose some near-far resistant codes. Also a very low complexity ML decoder for a subclass of the proposed codes is suggested  

In this paper, we introduce a new class of sigature matrices for overloaded synchronous CDMA systems that have a very low complexity decoder. While overloaded systems are more efficient from the bandwidth point of view, the Maximum Likelihood (ML) implementation for decoding is impractical even for moderate dimensions. Simulation results show that the performance of the proposed decoder is very close to that of the ML decoder. Indeed, the proposed decoding scheme needs neither multiplication nor addition and requires only a few comparisons. Furthermore, the computational complexity and the probability of error vs. Signal to Noise Ratios (SNR) are derived analytically  

Scaling of CMOS devices being aggressively decreasing by reduce of transistor dimensions. However, such level of integration leads to many physical limit and transistors cannot get much smaller than their current size. Quantum-dot Cellular Automate is a novel technology which significantly reduces physical limit of CMOS devices implementation, thus, it can be an appropriate candidate to be substituted for CMOS technology. In addition to high integration density of QCA circuits, other unique specifications such as high speed and low power consumption encourage researchers to utilize this technology instead of CMOS technology. In this paper, a new layout of XOR gate is presented in QCA...