Uplink Throughput in a Single-Macrocell/Single-Microcell CDMA System, with Application to Data Access Points

TL;DR

This paper analyzes the uplink throughput in a two-tier CDMA system with a microcell acting as a data access point, focusing on throughput distribution, average performance, and the influence of base-selection parameters.

Contribution

It introduces a model for the throughput of microcell users in a two-tier CDMA system, including a simple approximation for its distribution and analysis of key system parameters.

Findings

Microcell user throughput depends on interference and adaptive spreading factors.

Average throughput varies with system parameters like desensitivity in base selection.

Numerical results demonstrate the impact of base-selection parameters on system performance.

Abstract

This paper studies a two-tier CDMA system in which the microcell base is converted into a data access point (DAP), i.e., a limited-range base station that provides high-speed access to one user at a time. The microcell (or DAP) user operates on the same frequency as the macrocell users and has the same chip rate. However, it adapts its spreading factor, and thus its data rate, in accordance with interference conditions. By contrast, the macrocell serves multiple simultaneous data users, each with the same fixed rate. The achieveable throughput for individual microcell users is examined and a simple, accurate approximation for its probability distribution is presented. Computations for average throughputs, both per-user and total, are also presented. The numerical results highlight the impact of a desensitivity parameter used in the base-selection process.