Research On Upstream Bandwidth Allocation Algorithm Under The Convergence Network Of EPON And WLAN

Nowadays, EPON (Ethernet Passive Optical Network) has become the most promising fiber-based broadband access network technology due to the compatibility with the Ethernet network, high bandwidth, good maintenance, etc. But, EPON has some drawbacks in the practice, for example, the cost is relative high and it lack mobility. At the same time, the WLAN (Wireless LAN) has been deployed widely in the home, airport and office due to high mobility, low cost and easy use, but the channel of Wireless network is not stable and WLAN provides lower bandwidth for each user compared to the fiber-based techniques. Consequently, EPON and WLAN are complementary with each other. The convergence network of EPON and WLAN can take advantage of the two access network and reduce the shortage, which has good market potential. The research in this dissertation elaborates the convergence network of EPON and WLAN and emphasizes on the upstream bandwidth allocation algorithm. The main contents and innovations of this thesis are as follows:(1) In the analysis of the network of EPON and WLAN, this thesis designs two kind of convergence framework: the ROF (Radio over Fiber)-based framework and the baseband-based framework. The characteristic, key-technology and future application of the two kinds of convergence framework are elaborated in detail. On the consideration of technology maturity and upstream bandwidth allocation, the baseband-based convergence framework is adopted.(2) The upstream bandwidth allocation algorithm of EPON is elaborated in detail. Aiming at the shortage of the HG (Hybrid Granting) algorithm, this thesis designs a new upstream bandwidth allocation algorithm E-HG (Enhanced HG), which forecasts the flow of variable bit-rate service at the waiting time and adopts the PBS (priority-based scheduling). E-HG algorithm can assure the bandwidth of the low priority, decrease the delay of alterable bit-rate service and increase the system throughput. Simulation results match theoretical analysis well.(3) The upstream bandwidth allocation algorithm of WLAN is elaborated in detail. Aiming at the shortage of the simple scheduler algorithm in the HCCA (HCF Controlled Channel Access), this thesis designs a new upstream bandwidth allocation algorithm E-HCCA (Enhanced HCCA). E-HCCA algorithm can apply not only for the const bit-rate service, but also for the variable bit-rate service. Specially, E-HCCA algorithm takes high priority service first served, so even the system service loads is heavy, the delay of high priority service is low. E-HCCA algorithm also increases the flow numbers that system can accept. Simulation results match theoretical analysis well.(4) This thesis provides two kinds of upstream bandwidth allocation algorithm for the convergence network of EPON and WLAN: centralized bandwidth allocation and distributed bandwidth allocation. The advantage and disadvantage of the two algorithms are elaborated in detail. On the consideration of the signal cost, calculating complexity and system maintenance, this thesis adopts the distributed upstream bandwidth allocation algorithm, which the WLAN network adopt E-HCCA and the EPON network adopt E-HG Simulations results show that the distributed upstream bandwidth allocation algorithm can make the convergence network run more efficient and support all kinds of services well.