A Code-Based Packet Recovery Mechanism in Fiber-Wireless (FiWi) Access Networks

As a combination of fiber networks´ huge available bandwidth and wireless networks´ ubiquity and mobility, the fiber-wireless (FiWi) access network is considered as a promising network architecture for future networks. The wireless subnetwork of FiWi networks is responsible for users´ Internet access and connected to back-end fiber subnetwork. Inheriting from pure wireless networks, the wireless subnetwork is also vulnerable to the factors in surrounding environment such as noise, mutual interference of different users and etc. Although fiber links are quite good, they are not perfect. When a fiber link is long enough, the signal fading can not be ignored which may make receiver receive a false packet. The interference in wireless subnetworks and the signal fading in fiber subnetworks severely affect the quality of service in FiWi networks. In this paper, a code-based packet recovery mechanism in FiWi access networks is proposed. Based on the XOR coding, a packet which contains recovery message is generated by sender after sending several normal packets. The recovery packet follows these normal packets. Our packet recovery mechanism makes the receiver be able to cope with the situation of one packet loss, rather than request the sender to retransmit. The recovery packet generating algorithm and the packet recovery algorithm are also presented. Through extensive numerical simulation, we discuss the cost of packet recovery mechanism and compare its performance with the alternative without packet recovery mechanism.