An Analysis of the DS-CDMA Cellular Uplink for Arbitrary and Constrained Topologies

A new analysis is presented for the direct-sequence code-division multiple access (DS-CDMA) cellular uplink. For a given network topology, closed-form expressions are found for the outage probability and rate of each uplink in the presence of path-dependent Nakagami fading and shadowing. The topology may be arbitrary or modeled by a random spatial distribution with a fixed number of base stations and mobiles placed over a finite area. The analysis is more detailed and accurate than existing ones and facilitates the resolution of network design issues including the influence of the minimum base-station separation, the role of the spreading factor, and the impact of various power-control and rate-control policies. It is shown that once power control is established, the rate can be allocated according to a fixed-rate or variable-rate policy with the objective of either meeting an outage constraint or maximizing throughput. An advantage of variable-rate power control is that it allows an outage constraint to be enforced on every uplink, which is impossible when a fixed rate is used throughout the network.