As the number of Mobile IP (MIP) [C. Perkins, (1996)] users grow, so will the demand for delay sensitive real-time applications, such as audio streaming, that require seamless handoff, namely, a packet lossless Quality-of-Service guarantee during a handoff. Two well-known approaches in reducing the MIP handoff latency have been proposed in the literature. One aims to reduce the (home) network registration time through a hierarchical management structure, while the other tries to minimize the lengthy address resolution delay by address pre-configuration through what is known as the fast-handoff mechanism. We present a novel seamless handoff architecture, S-MIP, that builds on top of the hierarchical approach [H. Soliman et al. (2002)] and the fast-handoff mechanism [G. Dommety et al. (2002)], in conjunction with a newly developed handoff algorithm based on pure software-based movement tracking techniques [Z.-G. Zhou et al. (2002)]. Using a combination of simulation and mathematical analysis, we argue that our architecture is capable of providing packet lossless handoff with latency similar to that of L2 handoff delay when using the 802.11 access technology. More importantly, S-MIP has a signaling overhead equal to that of the well-known 'integrated' hierarchical MIP with fast-handoff scheme [H. Soliman et al. (2002)], within the portion of the network that uses wireless links. In relation to our S-MIP architecture, we discuss issues regarding the construction of network architecture, movement tracking, registration, address resolution, handoff algorithm and data handling.

/pdf/s-mip-a-seamless-handoff-architecture-for-mobile-ip-4lb0y0bpts.pdf

S-MIP: a seamless handoff architecture for mobile IP

Mobile IP, the current IETF proposal for IP mobility support, represents a key element for future All-IP wireless networks to provide service continuity while on the move within a multi-access environment. We conducted a performance evaluation of Mobile IPv6 and its proposed enhancements, i.e., Fast Handovers for Mobile IPv6, Hierarchical Mobile IPv6 and our proposed combination of them, using the network simulator ns-2 for the case of a 'hot spot' deployment scenario. The simulation scenario comprises four access routers and up to 50 mobile nodes that communicate in accordance with the IEEE 802.11 wireless LAN standard. The study provides quantitative results of the performance improvements obtained by the proposed enhancements as observed by a single mobile user with respect to handoff latency, packet loss rate and achieved bandwidth per station. As a complementary part of the study, the signaling load costs associated with the performance improvements provided by the enhancements has been analyzed. The simulation environment allowed us also to investigate the behavior of the protocol in extreme cases, e.g., under channel saturation conditions and considering different traffic sources: CBR, VoIP, Video and TCP transfers. While some simulation results corroborate the intention of the protocols specifications, other results give insights not easily gained without performing simulations. This study provides a deep understanding of the overall performance of the various protocols and supports the design process of a Mobile IPv6-based network when a decision of whether it is appropriate to implement any of the proposed Mobile IPv6 enhancements has to be made.

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A performance comparison of Mobile IPv6, Hierarchical Mobile IPv6, fast handovers for Mobile IPv6 and their combination

Handoff latency results in packet losses and severe End-to-End TCP performance degradation as TCP, perceiving these losses as congestion, causes source throttling or retransmission. In order to mitigate these effects, various Mobile IP(v6) extensions have been designed to augment the base Mobile IP with hierarchical registration management, address pre-fetching and local retransmission mechanisms. While these methods have reduced the impact of losses on TCP goodput and improved handoff latency, no comparative studies have been done regarding the relative performance amongst them. In this paper, we comprehensively evaluated the impact of layer-3 handoff latency on End-to-End TCP for various Mobile IP(v6) extensions. Five such frameworks are compared with the base Mobile IPv6 framework, namely, i) Hierarchical Mobile IPv6, ii) Hierarchical Mobile IPv6 with Fast-handover, iii) (Flat) Mobile IPv6 with Fast-handover, iv) Simultaneous Bindings, and v) Seamless handoff architecture for Mobile IP (S-MIP). We propose an evaluation model examining the effect of linear and ping-pong movement on handoff latency and TCP goodput, for all above frameworks. Our results show that S-MIP performs best under both ping-pong and linear movements during a handoff, with latency comparable to a layer-2 (access layer) handoff. All other frameworks suffer from packet losses and performance degradation of some sort. We also proposed an optimization for S-MIP which improves the performance by further eliminating the possibility of packets out of order, caused by the local packet forwarding mechanisms of S-MIP.

A comparison of mechanisms for improving mobile IP handoff latency for end-to-end TCP

Wireless communication is playing an important role in our daily life since it offers flexibility and mobility. New multimedia services demand data-rates of up to hundreds of Mbps and thus higher frequency bands are being explored to support these new high data rate services. However, to support mobility, handoff is a must in many of these networks and systems. In the mean time the 60 GHz band has received much attention due to its 5 GHz of the available spectrum globally. However, the 60 GHz channels face many challenges such as high attenuation and NLOS propagation. The high reduction in signal strength as a function of distance results in a small coverage area, thereby causing frequent handoffs for mobile terminals. In this paper, we discuss and compare handoff algorithms intended for WLAN, GSM, UMTS, etc. We study these algorithms from the point of view of their usability in 60 GHz networks and make recommendations for handoff algorithms in such networks.

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A Survey on Handoffs — Lessons for 60 GHz Based Wireless Systems

Current deployment of the wireless mesh networks (WMN) necessitates mobility management to support mobile clients roaming around the network without service interruption. Though Mobile IP and other previous protocols can be applied to WMNs to gain the micro-mobility as well as macro-mobility support, high signaling cost and long handoff latency problems still degrade the system performance significantly. In this paper we present a new mobility management scheme for WMNs, mesh mobility management (M3). It utilizes some WMN's features and combines the per-host routing and tunneling techniques to reduce the signaling cost as well as to shorten the handoff latency. Our analysis shows that significant benefits can be achieved from this scheme.

/pdf/a-mobility-management-scheme-for-wireless-mesh-networks-2ox3yd4kuq.pdf

A Mobility Management Scheme for Wireless Mesh Networks

Mobile IPv4 has been considered as the de facto standard in providing Internet mobility. However, as the demand for wireless mobile devices capable of executing real-time applications increases, it is necessary to provide superior handoff latency and quality of service (QoS). Mobile IPv6 is designed to resolve these issues, and has numerous applicable optimization techniques. Two ways of reducing the handoff latency, in both IPv4 and IPv6, have been proposed in the literature. One aims to reduce the (home) network registration time while the other aims to reduce the lengthy address resolution time when in a visiting network. We present a performance analysis of the current IETF proposals, namely, the hierarchical Mobile IPv6 architecture and the fast-handoff mechanism. The former is aimed at reducing the registration time while the later in reducing the address resolution time. We show through simulation that managing the registration process in a hierarchical fashion greatly reduces the overall handoff latency. Comparatively, the fast-handoff mechanism is even more capable of reducing the handoff latency. The simple superimposition of these two frameworks produces the best overall handoff latency result. However, the overall improvement is not a simple aggregation of the individual handoff latency gains. In fact, we discovered some rather non-trivial traffic behavior when these two frameworks are combined. We identify the causes which hinder the handoff performance and hence devise a set of design guidelines to improve the handoff latency further.

R. Hsieh

Papers

Performance analysis on hierarchical Mobile IPv6 with fast-handoff over end-to-end TCP