Optical and Wireless Hybrid Access Networks: Design and Optimization

The performance of optical/wireless hybrid networks is largely limited by the wireless part. To reduce the wireless transmission, we configure virtual channels in the optical infrastructure as shortcuts between selected gateways. Adding virtual channels changes the network topology and affects the optimality of gateway deployment. Meanwhile, the gateway locations dictate the traffic distribution that affects the selection of gateways for virtual-channel placement. We propose to jointly optimize the gateways and virtual channels, and formulate the optimization as a mixed integer programming problem. In addition, we design an efficient heuristic algorithm based on k-means clustering to iteratively optimize these two aspects. Our schemes are evaluated using various network settings (network size, number of gateways, etc.). In particular, a random topology with Ethernet traffic is studied for delay and throughput. Numerical results show that our design and optimization effectively reduce the wireless transmission, which leads to better scalability, smaller traffic delay, and larger throughput.