Soft handoff analysis for hierarchical CDMA cellular systems

Abstract

Abstract-A new soft handoff analysis for hierarchical code-division multiple-access (CDMA) cellular systems is presented. Hierarchical cellular architectures have been proposed to increase cellular system capacity and flexibility. In order to extend such architectures to CDMA-based systems, the performance of soft handoff in hierarchical architectures must be considered. We first develop an analytical method for studying the interference in hierarchical CDMA cellular systems. We then apply the obtained results to a soft handoff analysis model to study the performance of soft handoff in hierarchical architectures. It is observed that dynamic handoff parameter assignment, where parameters are dynamically adjusted according to given interference conditions, offers a more efficient handoff mechanism than fixed handoff parameter assignment.Index Terms-Active set, carrier-to-interference ratio (CIR), code-division multiple access (CDMA), hierarchical architectures, macrocell, microcell, soft handoff.

Hierarchical wideband multicarrier CDMA systems: Reverse link analysis

“…Assuming that maximal ratio combining at the receiver optimally combines the received signals from all transmitted subbands (8) where and are the transmit powers given that the MS is connected to BS and microcell, respectively, and and are the power-controlled combined received signal levels for MSs connected to macrocells and microcell, respectively. Given that an MS is connected to BS , the signal received through th subband by BS is (9) The expected value and second moment of are (10) An efficient method for calculating and has been presented in [14] and will not be reproduced here. We know has the Gamma probability density function (11) When calculating and , we need to consider two cases, interference and desired signal, when , , and are independent of each other.…”

“…Then, the conditional first and second moments of given are given as follows: mial probability law and the chain rule of probability, as shown in[14]. Then, the total th subband interference received by BS is if…”