Optimum Combining for Indoor Radio Systems with Multiple Users

This paper studies the use of optimum combining to increase the capacity of narrowband in-building radio communication systems with multiple users. We consider systems consisting of a base station with numerous remotes in a Rayleigh fading environment and study the problem of more users requiring channels than the number of channels available. A system is described that, with multiple antennas at the base station but only one antenna at each remote, uses optimum combining to suppress interfering signals. We show that this system, with M antennas at the base station, can achieve an M-fold increase in the number of users or tolerate M- 1 interferers from other systems. Thus, with optimum combining, radio communications can be used in high density, multiple user environments, such as within buildings, even when only limited bandwidth is available.