Mira Tayyiba

Comparison of FDMA and CDMA Capacities in a Wireless Local Loop (WLL) System

MS Thesis
Date: September 3, 1998

Abstract:

Wireless local loop (WLL) is the use of radio to provide a connection to users. In WLL, multiple access is one of important keys because the available WLL technologies differ in the multiple-access method. The choice of multiple-access method will affect system capacity. This paper is to evaluate capacities of FDMA, TDMA, and CDMA systems used in WLL. First, channel capacity is investigated. It gives the maximum number of channels that can be supported by a system. Then, traffic capacity is calculated. The result shows that FDMA system capacity can be increased by using a reduced cluster size in a sectorized system. Capacity in CDMA systems is driven by frequency reuse gain and tier number. The directionality of users' antenna significantly reduces the other cell interference, and consequently increases the system frequency reuse, which translates directly to a capacity increase. The result also shows that in a free space propagation, tier number plays an important role in system capacity, unlike in a mobile system where capacity is decided by the closest two tiers. In the last part of this paper, system capacity of a WLL system is compared with that of a mobile system. The result shows that WLL may not necessarily provide more capacity than mobile system if an omni-directional system is used.

Committee:

Milica Stojanovic (advisor)