The application of low noise amplifiers in CDMA cellular and PCS systems for coverage and capacity enhancements

Abstract

The paper examines the use of low noise amplifiers (LNAs) as a technique to enhance reverse-link coverage and capacity in a CDMA wireless network. The reduction of system noise figure for a base station is accomplished by installing LNAs between the receive antenna and the radio. Using noise figure theory, the paper develops an analytical model for the SNR improvement. The SNR models are found to be functions of the reverse-link noise rise, which constitutes a measure of the reverse-link capacity limits. Since the CDMA system uses reverse-link power control, the improvement in SNR is manifested in the reduction of the mobile's transmit power. In terms of capacity, the reverse-link capacity of a CDMA base station with installed LNAs has not improved. However, the capacity of a neighboring base station (with no LNAs) has improved. This is because the mobile within the coverage area of a base station (with LNA) now transmits less power and contributes less loading to the neighboring base station (with no LNA).