Evaluation of Downlink Performance of a Multiple-Cell, Rake Receiver Assisted CDMA Mobile System

Abstract

In wireless Code Division Multiple Access (CDMA) system, the use of power control is indispensable to combat near-far and fading problems. Signals transmitted over a multipath propagation channel which exhibits inter-path interference and fading. The receiver has to employ measures to mitigate these effects or it will incur severe performance degradation. A classic approach in CDMA communications is the rake receiver. In this paper, the downlink performance is estimated for a CDMA mobile system at the vertex of multiple adjacent cells. At the base station the received signal is coherently dispread and demodulated using a rake receiver. The effects of power control, error correction and rake receiver were also investigated on the assumption that the received signals undergo Rayleigh fading, lognormal shadowing, and frequency selective fading. The evaluation of performance measures of base to mobile link (downlink) of a multiple-cell CDMA mobile system is presented. This study demonstrates that significant performance improvements are achievable with combined use of power control, rake receiver and error correction scheme.

Evaluation of Multiusers’ Interference on Radiolocation in CDMA Cellular Networks

“…Assuming a large number of interferes, by virtue of the central limit theorem (CLT), the distribution of  can be approximated by a zero-mean Gaussian distribution [4,7,8] x is the log-normal fading on the path from this user to cell . j Let k P be the nominal power received at BS i from user i n .It is assumed that the power control m hanism overcomes both the large scale path loss and shadow fadin However, it does not overcome fast fluctuation of signal power due to Rayleigh fading [8,11]. As BS i exercises a power control over the MS, the actual transmission power…”

“…Hence, m=4;As we are restricting the interference from the first tier of interferer's, number of cells in the coverage area is 7. Hence, NBS = 7; Nominal power of MS, Pk = 1; Speed of radio signal, C = 3x108 m/s; Therper cell is uniform and every cell has same number of users N. The variable sets of parameters include: a) N: Num er of users per cell; of BS's participating in radiolocation; d)  : DLL(delay-locked loop) resolution. e) R: Radius of the cells.…”

Evaluation of Potential Dangers of Mobile Telecommunication Frequencies and Modulations

“…No technology covering virtually entire countries with its emissions has ever been rolled out as quickly as mobile telecommunications. This technology which comprises of either Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA) or Code Division Multiple Access (CDMA) are electromagnetic fields (EMFs) based [1]. At the same time, there are only few direct studies of the potential health risks of typical mobile telecommunications frequencies and modulations for the exposed population.…”

The Behaviour of Vertical Bell Laboratories Layered Space-Time Algorithm Combined with Multiuser Detection Schemes in Wireless Communication System

“…Multi input and multi output (MIMO) system has proved in the recent past to provide very high capacity without any increase in the transmission bandwidth and power. The information-theoretic capacity of these multipleinput multiple-output channels was shown to grow linearly with smaller numbers of transmit and receive antennas in rich scattering environments, and at sufficiently high signal-to-noise (SNR) ratios [4,5].…”