Research On IEEE 802.21-Based Heterogeneous Multi-Hop Networks

Network convergence is the main tendency of the future wireless communications,where the seamless handoff and ubiquitous coverage are the key contents.IEEE 802.12 protocol can complete the task of mobility management in heterogeneous network using a Media Independent Handover function(MIH) between Layer 2(MAC layer) and Layer 3(NET layer),which facilitate the seamless handoff without modifying PHY and MAC layers as well as the upper mobile protocol.Firstly,a new network structure is proposed to improve the coverage of the heterogeneous network composed of IEEE 802.16(WiMAX) and IEEE 802.11 (WLAN).The structure combines heterogeneous network with mutli-hop WLAN,thus enhancing the coverage of WLAN.Based on IEEE 802.21s protocol,nodes are established and managed in multi-hop backbone network.FIT MP with single mesh and double meshes are examined in a real network environment.And the management of multi-hop network is also presented.Secondly,according to the characteristics of multi-hop network,new primitives are augmented,and the frame structure is adapted to the mobility management in the multi-hop heterogeneous network.Mobile node controlled handoff and network controlled handoff are typically analyzed with respect to transmissions of MIH message and decision strategy.Finally,the handoff process is simulated in the IEEE 802.21 based multi-hop heterogeneous network with NS2.Simulation results show the success of the mobility management of IEEE 802.21 protocol in the network.With velocity of 10 m/s of the mobile terminal,the handoff delay is no more than 33 ms and the number of lost packets is no more than 2;when handoff inversely,the corresponding delay and lost packet number are no more than 8 ms and zero,respectively.