Design of a wireless backhaul network for microcells

The use of microcells is an attractive option for providing high data rate access for fixed and low mobility users. We propose and analyze a wireless backhaul network for connecting microcells to the wireline network. In the proposed network, several microcellular radio ports are connected to a so called hub through radio links. These hubs are then connected to the wireline network using cable or fiber. For ease of deployment, we propose that omnidirectional antennas be used at the radio ports and sectored antennas be used at the hubs. Our results show that for 95% of the links, a link reliability of 99% may be achieved with an effective frequency reuse of 3 by using site-selection, flexible channel assignment, power control and two-branch minimum mean square error combining. For the remaining 5% of the more vulnerable links, a direct wireline connection may be provided. We also find that power control plays a critical role in reducing the variation of the link performance over time. In addition, the best performance is achieved by jointly optimizing the receiver, i.e., the diversity combining weights, and the transmit power settings. We show that this joint optimization may be implemented in a distributed manner, making it attractive for use in real systems.