Nilanjan Banerjee

Mobility support in wireless Internet

The tremendous advancement and popularity of wireless access technologies necessitates the convergence of multimedia (audio, video, and text) services on a unified global (seamless) network infrastructure. Circuit-switched proprietary telecommunication networks are evolving toward more cost-effective and uniform packet-switched networks such as those based on IP. However, one of the key challenges for the deployment of such wireless Internet infrastructure is to efficiently manage user mobility. To provide seamless services to mobile users, several protocols have been proposed over the years targeting different layers in the network protocol stack. In this article we present a cross-layer perspective on the mobility protocols by identifying the key features of their design principles and performance issues. An analysis of the signaling overhead and handoff delay for some representative protocols in each layer is also presented. Our conclusion is that although the application layer protocol is worse than the protocols operating in the lower layers, in terms of handoff delay and signaling overhead, it is better suited as a potential mobility solution for the next-generation heterogeneous networks, if we consider such factors as protocol stack modification, infrastructure change, and inherent operational complexity.

Analysis of SIP-based mobility management in 4G wireless networks

Providing seamless mobility support is one of the most challenging problems towards the system integration of fourth generation (4G) wireless networks. Because of the transparency to the lower layer characteristics, application-layer mobility management protocol like the Session Initiation Protocol (SIP) has been considered as the right candidate for handling mobility in the heterogeneous 4G wireless networks. SIP is capable of providing support for not only terminal mobility but also for session mobility, personal mobility and service mobility. However, the performance of SIP, operating at the highest layer of the protocol stack, is only as good as the performance of the underlying transport layers in such a heterogeneous environment. In this paper we analyze the handoff performance of SIP in a IP-based 4G network with Universal Mobile Telecommunication System (UMTS) and Wireless LAN (WLAN) access networks. Analytical results show that the handoff to a UMTS access network introduces a minimum delay of 1.4048 s for 128kbps channel, while for handoff to a WLAN access network the minimum delay is 0.2 ms. In the former case the minimum delay is unacceptable for streaming multimedia traffic and requires the deployment of soft-handoff techniques in order to reduce the handoff delay to a desirable maximum limit of 100 ms.

Hand-off delay analysis in SIP-based mobility management in wireless networks

Recent years have seen a tremendous amount of effort toward the development of wireless Internet infrastructure and approaches to solve various problems associated with it. One of the major stumbling blocks is the mobility management in such an infrastructure. Several mobility management protocols have been proposed working at different layers of the protocol stack, but each comes with its own set of requirements and shortcomings. We observe that by and large the mobility requirements can be satisfied by using a simple application layer mobility management protocol. Although the session initiation protocol (SIP), originally developed as an application layer signaling protocol, offers mobility management capability, yet there are some associated delays that need careful investigation. In this paper, we study analytically the SIP based hand-off delay in third generation (3G) wireless networks. Our performance results conclude that in terms of hand-off delay, SIP is not suitable for supporting streaming media with stringent delay requirements.

Fast determination of QoS-based multicast routes in wireless networks using genetic algorithm

In this paper, we propose a novel multicast route discovery scheme for wireless networks, satisfying quality of service (QoS) constraints such as bandwidth requirement and end-to-end delay guarantees. The underlying approach is based on a genetic algorithm (GA). The problem of (optimal) multicast route discovery is NP-hard when the network state information is inaccurate, which is so common in the wireless domain. In general, this makes it difficult to determine multicast routes on demand, and hence the network resources are never used to their full potential. The proposed GA based method, however, is shown to discover multicast routes for large networks within few iterations, even with imprecise network information, and thus it ran be used for an on-demand basis. We observed an approximate linear relationship between the computation time and the number of nodes in a network. In addition we have studied the effects of choosing the fitness function of the GA.

An efficient multi-objective QoS-routing algorithm for wireless multicasting

The increasing demand of real-time wireless communication has led to the development of quality-of-service (QoS) based routing. Most of the wireless multimedia applications require strict QoS guarantee (e.g. delay, bandwidth) during the communication between a single source and multiple destinations. This gives rise to the need for an efficient multicast QoS-routing strategy. Determination of such QoS-based optimal multicast routes boils down to a multi-objective optimization problem, which is computationally intractable in polynomial time. We propose a new multicast tree selection algorithm based on non-dominated sorting technique of the genetic algorithm to simultaneously optimize multiple QoS parameters. Simulation results demonstrate that the proposed algorithm is capable of discovering a set of QoS-based near optimal, non-dominated multicast routes within a few iterations. From this set the user can choose desirably favorite solution depending on specific QoS requirements. The scalability and the performance of the algorithm with increasing number of network nodes is also presented.

Network assisted IP mobility support in wireless LANs

In recent years, wide bandwidth and low cost wireless LAN (WLAN) technology has emerged as a competitive choice for high speed wireless Internet access. To support the Internet mobility for the frequently moving mobile nodes in the local WLAN environment, Mobile IP has been found to be inefficient due to its high location update and packet delivery cost. This paper proposes an alternative architecture for network-layer mobility support using dynamic client configuration and transparent proxy mechanism. The attractive feature of our solution is that it requires no change in the legacy network infrastructure. We have implemented a prototype of the proposed architecture, and have taken experimental measurements to evaluate its performance. Experimental results show that the proposed architecture is capable of supporting IP mobility with the handoff delay less than a second. In addition, we have done an analytical study to test the scalability of the proposed architecture. Results show that performance of the architecture is not severely affected by the user mobility and a commonplace router is capable of supporting a considerable number of such users.

MODeRN: multicast on-demand QoS-based routing in wireless networks

Multicast route computation satisfying specified quality-of-service (QoS) requirements for wireless networks is computationally complex due to the inherent uncertainty in the wireless medium. Multicast route selection which directly corresponds to the Steiner tree computation in graphs also adds to the complexity. Hence designing an on-demand, QoS-based multicast routing scheme is an NP-hard problem. If such routing is statically done beforehand, it does not capture the dynamism of a network. We propose a genetic algorithm (GA) based path (route) computation scheme-multicast on-demand QoS-based routing in wireless networks (MODeRN), which reduces the computational cost. We also study the performance of MODeRN, and compare it with a commonly used path pre-computation method. The results demonstrate that our approach is more efficient.

IP MOBILITY PROTOCOLS FOR WIRELESS INTERNET

Research in mobile communications has gained a lot of importance since the rapid growth of wireless networks and portable devices. The proliferation of Internet in every aspect of life has urged the service providers to provide seamless user mobility. While the Second-Generation (2G) wireless system has brought mobile telephony, the Third-Generation (3G) is expected to bring in high-speed data and multimedia communication to the mobile users. 3G not only promises much higher data rate than 2G technology, but also opens up the avenue of providing a rich set of applications like location-based services, multimedia messaging services and customized information. However, the evolution of 3G from 2G requires the change of core network from circuit to packet switching mode and building a core network that is independent of access technology. The Internet Protocol (IP) [1] has been the natural choice as a packet-switched protocol because of the increasing dominance. Another important reason for adoption of IP is because it is a network layer protocol that can be used with any kind of access network technology.