Performance Modeling and Analysis of Multi-Path Routing in Integrated Fiber-Wireless Networks

In an integrated fiber and wireless access (FiWi) network, multi-path forwarding may be applied in the wireless subnetwork to improve throughput. Due to the delay difference along multiple paths, reordered packets of a flow may arrive at the Optical Line Terminal (OLT) waiting for dispatching to the Internet, which may deteriorate the TCP performance. As all traffic in a FiWi network is sent out through the OLT, the OLT serves as a convergence node which naturally makes it possible to resequence packets at the OLT before they are sent to the Internet. The fundamental difference between resequencing at the end systems and resequencing at an intermediate node (e.g., the OLT) is that very tight resequencing delay can be tolerated in the latter. Thus, resequencing at the intermediate nodes must be fast enough. In this paper, we propose an integrated flow assignment and resequencing approach which jointly determines the probability of sending packets along each path from the source and needs virtually zero resequencing delay at the OLT to reduce the out-of-order probability when packets are injected to the Internet from the access network. Simulation results validate our analysis and the effectiveness of the proposed integrated flow assignment and resequencing approach.