Figure 1: WiMAX layered architecture with location of proposed protocol implementation
Secondly, we discuss the capacity of MIMO and random MIMO channels in WiMAX. Furthermore, we also developed the analytical model of the space time coding technique to achieve antenna diversity gain.
Thirdly, we proposed an Adaptive Modulation and Coding (AMC) controller that adaptively switch to required MCS to achieve desired level of QoS and link stability. The aim of this controller is to create a universal state machine where the states correspond to different MCS and states can be changed adaptively based on throughput, channel condition and node mobility. The scheme is robust because MCS values can be changed per frame / per user basis.
Fourthly, to maximize the utilization of radio resources, we proposed a model for channel allocation of new calls and channel adjustment of ongoing calls without interrupting the ongoing call’s QoS requirement. We used a bi-matrix non cooperative game theoretic model where two players (WiMAX base station and a new user) apply a set of strategies. The calls are analyzed based on user type, call category, type of service class required and decide whether new calls to be accepted or rejected. The decision is taken based on the best response function of any strategy that satisfies Nash equilibrium.
Finally we derive a unified optimization framework to attain different degrees of performance trade-off between throughput, end-to-end delay, jitter and load to achieve optimized QoS in Mobile WiMAX.
Additional focus of this dissertation is the development and analysis of WiMAX- WiFi integrated architecture.
Performance Analysis Of Overlay Based Integrated Heterogeneous Wireless Networks
Mobile computing for Personal Communication Service (PCS) that offers mobile users anytime, anywhere bi-directional reliable access to the Internet. Mobile IP as a network layer protocol provides solutions to the requirements of mobile computing. Due to terminal mobility and change of service area, efficient IP mobility support is an important issue in heterogeneous network in order to minimize packet loss and hand over latency to the mobile users. In this work we have prepared a through analysis of various mobile IP protocols and analyzed the performance of GTP protocol in a customized heterogeneous network and there handoff performances. We propose an overlay based architecture of heterogeneous networks comprising all present and future networks such as 2G/2.5G/3G/WLAN/Wimax etc. We propose a crossover switch to manage and control vertical handoff and interlayer mobility .performance of the proposed GWON (Global Wireless Overlay Network) architecture have been analyzed with simulation using NS-2.The results show that vertical handoff from one network to another network can be performed within an accepted delay without any call drop. The results also depicts an improvement of handoff delay with the protocol compared to the existing other protocol.
It is anticipated that all the current networks will co-exist along with the all-IP based future networks. We therefore propose global overlay architecture GWON with four layers of dissimilar networks containing all the existing networks. The structure of the proposed GWON is depicted in figure 1.1. Layer 1 contains the core network of WLANs. Layer-2 contains 3G cellular with both UMTS and CDMA2000 systems overlaid on the base network (Layer-1). Layer-3 contains mostly deployed cellular systems GPRS and GSM overlaid on top of 3G. Considering the wide difference in bandwidth, we subdivide layer-3 with GPRS as layer-3L (lower end) and GSM as layer-3U (upper end). Layer-4 contains Satellite system. The bandwidth of the networks are 54Mbps (L-1), 2Mbps (L-2), 180Kbps (L-3L), 10Kbps,(L-3U) and 3-64kbps (L-4).
Since future networks would be all-IP based, we consider the basic Mobile IP (MIP) protocol to support seamless mobility over heterogeneous networks although many variants of basic MIP with improved performance are available. We also propose a high speed Cross-over Switch (CSW) to connect inter-layer base stations over heterogeneous networks similar to proposal in . The CSW supports inter-layer mobility and accessibility. When it decides to handoff a user from one network to another network, it also directs subsequent packets to the new base station. It is also capable of decision making in packet transfer between different heterogeneous networks. Each network would identify a pilot Access Point (PAP) or pilot MSC (PMSC) that links the CSW. The multilayer CSW is equipped with a high-speed server to store database containing packet formats, routing information (for PAP/PMSC/GGSN etc). When an IP packet arrives at CSW, it forwards the packet as per routing decision to the destination network using proper link. Packet format may be changed if tight coupling method is used. For example, a packet destined for UMTS, involves loose coupling and enter into the network through pilot GGSN (PGSN) without change of format. But packet destined for CDMA2000 needs tight coupling and its format needs to be changed. Figure 5.2 represents the overall architecture of the proposed GWON. The CSW is connected with different networks through different interfaces. WLAN is connected through PAP; 3G networks are connected with PGSN and packet Data serving node (PDSN); GPRS system is connected through PGSN and GSM system is connected through PMSC.