Spatial and spectral radio resource enhancement for urban spectrum reuse

Radio networks experience the greatest spectrum scarcity in urban environments. Dynamic radio access enables simultaneous and opportunistic spectrum reuse. This paper considers frequency division duplexing cellular networks, where every mobile user (MU) is allocated a frequency channel for uplink transmission to the base station (BS). Previously a frequency reuse model has been proposed for low power communications among secondary users (SU) in a cell. In the system the secondary user controls its transmit power to minimize interference at the nearest base station. This paper considers reusing frequencies within a cell to allow mobile users in outage to use other active users as relays to the base station. Different criteria are compared for choosing the relay frequency channels to be reused. Simulations consider urban large scale propagation conditions in a multicell environment. Results show significant reduction in the overall outage probability for the enhanced cellular network. The algorithm allows cooperation to share available resources without changing hardware or networks.