A radio access system with distributed antennas

Abstract

This paper analyzes a radio access system that has multiple antennas spatially distributed throughout each cell, instead of a single antenna at each cell. The same signal is simulcast by each antenna in the cell. The signals at a given cell could be multiplexed and modulated for radio transmission at a single node, then transmitted on a coaxial cable distribution system to and from the distributed antennas in a cell. Frequency translation and radio frequency (RF) amplification may need to be performed at each antenna, except for indoor applications with short coaxial cables. This paper presents calculations of signal-to-interference ratios (SIR) and handoff performance for cells with distributed antennas. It is shown that the use of distributed antennas can substantially increase the SIR above a system with a single antenna per cell, and this increase is quantified. It is also shown that increasing the number of antennas results in better overall handoff performance, with a lower number of handoffs and higher received signal power. Minimizing the number of handoffs will reduce the impact of wireless services on network elements.