Multiple Access for Transmissions Over Independent Fading Channels

TL;DR

This paper introduces a multilevel detection technique enabling multiple users to share the same resource over independent fading channels, effectively increasing user capacity in CDMA systems with some performance trade-offs.

Contribution

The paper presents a novel MLDT method that allows multiple users to share signature sequences in CDMA, increasing capacity without requiring additional resources.

Findings

User capacity can be doubled or tripled with MLDT

Some BER performance degradation occurs

Effective resource sharing in CDMA systems

Abstract

We propose to employ a multilevel detection (MLDT) technique to allow multiple users which respectively transmit messages over independent fading channels to share the same resource, e.g., the same signature sequence in the CDMA (code division multiple access) system. The users are separated by the different channel gains including amplitudes and phases resultant from the independent fading channels. In a CDMA system with a fixed amount of available signature sequences, the number of users can be doubled or tripled by using MLDT although there is the cost of some BER performance degradation.