Research On Some Key Technologies Of Next Generation Broadband Mobile Internet

In recent years, the maturity and popularity of new physical layer technologies such as OFDM and MIMO leads to the increasing of wireless link bandwidth. The data link layer protocols of some broadband wireless networks which adopt these advanced physical layer technologies have been improved to take full advantage of the increased physical layer transmission capability. What manifests the above-mentioned technical background is the rapid development of IEEE 802.11/15/16/20 based broadband wireless networks. With further improvement in bandwidth, mobility and quality of service (QoS) support, the superiority of these broadband wireless networks over 3GPP and 3GPP2 cellular networks becomes more prominent. 3GPP and 3GPP2 have to start LTE and AIE plan to deal with such shocks. IEEE 802.11, which has been accepted as the mainstream protocol for wireless local area networks (WLANs), still experiences continuous enhancement in access rate, QoS and mesh capability. Due to many advantages, IEEE 802.16 has been considered as the mainstream protocol for wireless metropolitan area networks (WMAN). Thus, the existing mobile wireless network will enter a special stage along with the evolution towards 4G networks. In this special stage, the cellular networks and the IEEE 802 series of broadband wireless networks compete, complement and integrate with one another. We define such stage of the evoluting mobile wireless networks as next generation broadband mobile Internet (NGBMI). NGBMI is not 4G network, but a transitional form for the evolution of the existing wireless network towards 4G network.To provide users QoS-guaranteed mobile multimedia services with anytime and anywhere access through a variety of ways is the design goal of NGBMI. This paper believes that three issues must be concerned in order to achieve this goal. Firstly, NGBMI needs to provide high performance mobile management to meet the QoS requirement of handover delay for mobile multimedia services. Mobile IP is the natural choice for mobility management in 4G network. However, Mobile IP is only suitable for macro-mobility management and it causes low efficiency for mobile multimedia services in micro mobility. Therefore, the feasible solution is to enhance the micro-mobility management extension of Mobile IP. Secondly, NGBMI must enhance its MAC layer QoS capability to provision QoS in packet delievery for mobile multimedia services, i.e., transmission delay and delay jitter, etc. Due to the limited bandwidth, high bit error rate and time-varying characteristics of the wireless link, QoS provisioning in wireless networks is not as easy as their wireline counterpart in which only IP and above-layer mechanisms can achieve the goal of QoS guarantee. In recent years, to provision QoS for multimedia services in wireless networks through MAC layer mechanisms has been the focus of the academy. To provide QoS guarantee for mobile multimedia service in MAC layer is a decisive selection and important opportunity for QoS provisioning in wireless networks. IEEE 802.11e and IEEE 802.16 are two typical QoS-aware MAC protocols in wireless networks and they are the particular concern of this dissertation. However, the MAC layer QoS mechanisms of these two protocols need further study. Thirdly, NGBMI must integrate heterogeneous wireless networks including 3GPP/3GPP2 celluar mobile networks and IEEE 802 broadband wireless networks in order to provision QoS for mobile multimedia services in heterogeneous wireless environments. The Media Independent Handover (MIH) which is proposed by IEEE 802.21 represents the trends for the integration of heterogeneous wireless networks. However, MIH is still in standard-setting stage and need improvement. Therefore, we need to examine the way to apply MIH in NGBMI in order to improve the handoff performance in heterogeneous enviroment. These above-mentioned issues have a strong academic and practical value.Based on the project supported by doctoral fund of ministry of education of china (No. 20040013010), this dissertation addresses micro-mobility management, MAC layer QoS mechanisms and the integration of heterogeneous wireless networks in NGBMI and makes some contributions as follows.(1) Micro mobility management in NGBMI. The current status and future trends of IP micro mobility are summarized. The motivation of deploying Multi-level HMIPv6 (M-HMIPv6) in NGBMI and the literature of MAP selection for M-HMIPv6 networks are presented. To overcome the weakpoint of existing MAP selection schemes in QoS support, a theoretical model to characterize the impact of MAP selection on handover performace for multimedia services is established. Based on this model, a formula to estimate Average Handover Delay (AHD) is derived. Then, a QoS-aware MAP Selection (QMS) scheme is proposed. The effectiveness of the model and the performance of QMS scheme are evluated by NS-2 simulations. The result demonstrates that the AHD of mobile multimedia services in NGBMI can be reduced effectively with QMS scheme.(2) MAC layer QoS mechanisms of NGBMI. The importance of MAC layer QoS schemes to support mobile multimedia services in NGBMI is illustrated. The MAC protocols of both IEEE 802.16e and IEEE 802.11e are studied. As to the IEEE 802.16e, we propose a QoS scheduling scheme and prove the effectiveness of the scheme through NS-2 simulation. Then, some suggetstions for further improvement are presented. As to IEEE 802.11e EDCA, we evaluate the QoS of multimedia Services in single hop infrastructure mode and multihop ad hoc mode. We show that the performance of EDCA in multihop environment is poor. To address the issue, we propose a novel scheme coined Active Drop enabled Adaptive Priority (ADAP) scheme in IEEE 802.11e EDCA-based multihop networks. Through NS-2 simulation, we demonstrate the performance gain of the proposed scheme over EDCA.(3) Integration of heterogeneous wireless networks in NGBMI. The current status and future trends for heterogeneous wireless networks integration in NGBMI are summarized. A novel layer two trigger based F-HMIPv6 is proposed and is applied to WiMAX network. Through NS-2 simulation, we prove the effective of the proposal. Then, we propose MIH-based F-HMIPv6 and apply it in WiMAX-WiFi heterogeneous environments. NS-2 simulation is conducted to evaluate the performance. The results demonstrate that the MIH-based F-HMIPv6 protocol can bring considerable performance gain in WiMAX-WiFi heterogeneous networks. Therefore, it is quite promising in NGBMI.In order to to meet the requirement of mobile multimedia services, this dissertation studies three key technologies including the micro mobility management, MAC layer QoS mechanisms and the integration of heterogeneous wireless networks in NGBMI. The research results are helpful for the optimization of NGBMI and the evolution of mobile wireless networks.