Study on Traffic Shedding for Soft-Handoff Using MC-CDMA in Wireless ATM Networks

Abstract

In wireless ATM mobile communication environments, an abrupt increase in the number of mobile users in a specific base station (BS) will overload the BS and turn it into a so-called hot-spot cell, which causes an unbalanced traffic load condition if the traffic load in the neighboring BSs is light. In order that efficiently allevates to utilize a limited bandwidth, it is necessary to use a good mobile handoff strategy to alleviate unbalanced traffic load condition. This paper proposes a complete traffic shedding algorithm (CTSA) for soft handoff efficiently to alleviate the overloaded traffic in a hot-spot cell by adjusting handoff parameters, which virtually reduces the service coverage of the heavy loaded BS without adjusting the transmission power. Mobile terminals (MT) located in the outer area of the hot-spot cell will be handed off early to the neighboring BSs with light traffic load; and MTs in the neighboring BSs will not be handed off to the hot-spot cell, so that the traffic load of the hot-spot cell can be decreased. After analyzing the proposed algorithm and comparing the other methods, variable threshold soft handoff (VTSH) and enhanced soft handoff (ESH), by simulation, the performance of CTSA is better than the others. CTSA obviously increases system throughput and decreases soft handoff call dropping ratio, new call blocking ratio, and total call refusing ratio.