Capacity of a multihop mesh arrangement of radio cells connected by free-space optical links

Provision of multimedia services to both stationary and non-stationary terminals is one of the key challenges in modern day telecommunications. A multi-tiered cellular radio system may provide adequate capacity needed to ensure reliable delivery of high quality broadband services to home, office, and mobile users. At the lowest tier, one may envisage picocellular base stations interconnected via short, highly focused free-space optical links, in a multihop mesh arrangement, thereby eliminating the need for new broadband access cabling to backhand traffic from the base stations. Ultimately, the traffic generated in these picocells must be relayed to an entry/exit port (end-office) of the core network. An intelligent routing/load-balancing strategy will help avoid hot spots on the mesh and increase network capacity. The performance metric would be the probability that a newly generated virtual connection must be blocked to maintain QoS guarantees, within this mesh network. A new dynamic routing/load-balancing algorithm is proposed to achieve high performance in terms of blocking probability in the presence of both uniform and nonuniform traffic distributions. Simulation results show that the algorithm dramatically helps in reducing congestion at hot spots in the network. For a toroidal grid configuration it is seen that the new dynamic routing to different end-offices achieves a 20% reduction in blocking probability when compared with a routing scheme wherein picocells have static affiliations with end-offices.