Design And Simulated Implementation For Protection Algorithms Based On Connection Availability In Wireless-Optical Broadband Access Networks

With the increasing popularity of broadband services, such as IPTV, HDvideo and facetime, the broadband access network is experiencing a rapid development. Compared with the traditional access technologies, hybrid Wireless-Optical Broadband Access Networks (WOBAN) provides the larger bandwidth capacity, more flexible network control platform, higher Quality of Service (QoS) and better support for multimedia applications to meet the users'requirements. Therefore, WOBAN is a promising architecture for access networks and it has become a hot issue in recent years.Since WOBAN usually carrries a lot of high-rate traffic flows, once the network components fail (e;g;, fiber cut), most of the traffic flows will be interrupted, which causes the huge economic loss. Thus, it is necessary to introduce the survivability into WOBAN for enhancing its robustness. This thesis focuses on the survivability issue of WOBAN. In WOBAN, the Wireless Mesh Network (WMN) at front-end is self-healing, while the Passive Optical Network (PON) at back-end cannot guarantee survivability due to its tree topology. Thus, this thesis considers the fiber failure in the back-end PON.Most of the previous works suffer from the challenges including underutilized backup resource, unreasonable assumption of failure scenario and high cost of network deployment. For this consideration, this thesis considers the protection of PON by means of wireless rerouting and proposes the protection algorithm based on connection availability. First, given the fiber failure probability, we propose the availability models of optical and wireless conenctions. Then, each primary ONU is assined a backup ONU, which allocates one unit of residual capacity to each traffic demand in the primary ONU as the backup capacity. Under the constraints of optical connection availability and full protection, a Backup ONU Capacity Allocation (BOCA) algorithm is proposed to optimize the allocation of backup ONU capacity with the objective of minimizing the number of the backup ONU capacity. Finally, by deploying the backup radios for the wireless routers, the wireless bacup paths are established between each pair of primary and backup ONUs. Each traffic demand is allocated one unit of radio capacity. Under the constraints of wireless connection availability and full protection, a Backup Radio Deployment Algorithm (BRDA) is proposed to optimize the computation of wireless backup paths, deployment of backup radios and allocation of backup radio capacity, aiming to minimize the deployment cost of backup radios.Based on the VC++6.0 sofeware, the simulation platform is established to evallluate the performance of the proposed BOCA and BRDA algorithms and compare them with the previous approaches. The MFC is used to output the intuitive figures for the topology of network deployment. Simulation results show that the proposed algorithms can achieve the suboptimal solution for the allocation of backup ONUs capacity and the deployment of backup radios. Compared with the previous protection ·approaches for WOBAN,the algorithms proposed in this thesis can not only provide full protection but also save the consumption of backup resource and the cost of network deployment.