Multiuser communications using beam-tilting antennas

This paper proposes means to exploit the additional degrees of freedom that can be achieved by using beam-tilting antennas for the purposes of multiuser communication without substantially increasing investment in system resources. Specifically, by using such beam-tilting antennas the wireless channel can be used as a means to spread the users in space rather than in frequency as is currently the norm in spread spectrum systems. This technique thus allows multiuser communications without increasing spectrum usage. The performance of such a system is characterized in terms of average bit error rate for various number of users and for different amounts of correlation between the channels in different beam directions.