WiFi-based point-to-multipoint systems are a cost-effective solution for providing high-bandwidth connectivity to remote rural regions. However, current point-to-multipoint deployments are hampered by several challenges. Their capacity to support a large number of clients simply by increasing the number of radios at the base station is limited because space restrictions on radio towers bound the number of antennas that can be installed at one physical location. Also the limited availability of wireless channels restricts the number of clients that can be simultaneously supported by a base station at any point of time.   In this paper, we explore high-throughput architectures for point-to-multipoint networks. We show how we can increase the number of radios at the base station without increasing the number of antennas simultaneously. We propose a simple yet practical multiplexing design that uses cheap RF combiner/splitter devices for multiplexing several radios onto a single antenna. We also examine a more general design that uses RF switches, and which allows us to allocate radios to antennas dynamically based on client traffic demands.   As a proof of concept, we demonstrate and evaluate the simple case of combining up to three radios operating on different channels onto only one antenna, using off-the-shelf combiner/splitters and attenuators. We show that not only is such a design feasible, but also that the achieved link throughput in both directions is as good as the one obtained by using separate antennas for each radio, as long as we provide sufficient RF isolation between the multiplexed radios.
['Ramakrishna Gummadi', 'Rabin K. Patra', 'Sergiu Nedevschi', 'Sonesh Surana', 'Eric A. Brewer']
A radio multiplexing architecture for high throughput point to multipoint wireless networks