Single-user adaptive and multiuser receivers for DS-CDMA in peer-to-peer packet radio networks

The performance of direct-sequence spread-spectrum (DS-SS) in packet radio networks suffers from the near-far problem. This near-far problem can be alleviated by using either a multiuser receiver or a single-user adaptive receiver along with centralized or distributed power control. This paper compares the feasibility of using a multiuser receiver based on selective parallel or successive interference cancellation technique with a single-user adaptive receiver in a peer-to-peer packet communication environment. The performance of an N-tap chip-rate linear adaptive receiver (CHRT-LAR) with normalized least-mean square algorithm (NLMS) is analyzed. For the single-user adaptive receiver, one user's spreading code and delay is known at the receiver, whereas the multiuser detector requires knowledge of the spreading codes and delays of all the users producing significant interference. To illustrate their potential for ad hoc networks, the BER performance and complexity of these two detection schemes are compared in this paper.