Spectral Efficiency of Randomly Spread DS-CDMA in a MUlti-Cell Model

摘要

A simple multi-cell uplink communication model is suggested and analyzed for optimally coded randomly spread direct sequence code division multiple access (DS-CDMA) multiuser detection strategies. We adhere to Wyner's (1994) infinite linear cell array model, according to which only adjacent cell interference is present, and characterized by a single parameter 0 =< alpha =< 1. We confine our discussion to asymptotic analysis where both the number of users and the processing gain go to infinity, while their ratio is kept fixed and finite. We focus on single cell-site processing and consider the matched filter detector, "optimum" detection with adjacent cell interference treated as Gaussian noise, the linear MMSE detector, and a Decision-Feedback MMSE detector with linear MMSE processing of adjacent cell interference. Spectral efficiency is evaluated under three power control strategies: equal recived powers (for all users), equals rates, and a mximal spectral efficiency policy. COmparative results demonstrate how performance of the different detectors is affected by the introduction of inter-cell interference, and what is the penality associatedwith the randomly spread coded DS-CDMA strategy.