Support Mobility Management Research Articles

Optimal Utilization and Effects of Inaccurate Estimation in Mobile Database Failure Restoration

Mobility databases such as home location register and visitor location register are adopted to support mobility management in personal communications services networks. If a visitor location register fails or crashes, the subscribers' services will be seriously degraded due to the loss or corruption of location information. In this paper, we optimize utilization of demand re-registration messages for an adaptive p-persistent backoff database failure restoration scheme. An analytical model is developed and validated with simulations to obtain the optimal utilization using appropriate parameters so that the failed visitor location register is restored with the fastest speed. Some interesting aspects on the performance are studied and their deep insights are observed, such as effects of message sizes on choices of system parameters, effects of the inaccurate estimated number of stations, etc. One observation is that optimizations of utilization and successful transmission probability are two different goals, and a value to achieve the optimal successful transmission probability does not necessarily ensure optimal utilization. Furthermore, we also propose a scheme how to handle the problem with inaccurate (estimated) number of stations.

A Cross-Layer (Layer 2 + 3) Handoff Management Protocol for Next-Generation Wireless Systems

Next-generation wireless systems (NGWS) integrate different wireless networks, each of which is optimized for some specific services and coverage area to provide ubiquitous communications to the mobile users. It is an important and challenging issue to support seamless handoff management in this integrated architecture. The existing handoff management protocols are not sufficient to guarantee handoff support that is transparent to the applications in NGWS. In this work, a cross-layer (layer 2 + 3) handoff management protocol, CHMP, is developed to support seamless intra and intersystem handoff management in NGWS. Cross-layer handoff management protocol uses mobile's speed and handoff signaling delay information to enhance the handoff performance of mobile IP that is proposed to support mobility management in wireless IP networks. First, the handoff performance of mobile IP is analyzed with respect to its sensitivity to the link layer (layer 2) and network layer (layer 3) parameters. Then, a cross-layer handoff management architecture is developed using the insights learnt from the analysis. Based on this architecture, the detailed design of CHMP is carried out. Finally, extensive simulation experiments are carried out to evaluate the performance of CHMP. The theoretical analysis and simulation results show that CHMP significantly enhances the performance of both intra and intersystem handoffs

Mobility management support and performance analysis for wireless MPLS networks

AbstractMulti‐Protocol Label Switching (MPLS) is deployed in the Internet backbone to support service differentiation and traffic engineering. In recent years, there has been interest in extending the MPLS capability to wireless access networks for mobility management support. In this paper, we present analysis of Micro Mobile MPLS, a new micro‐mobility management scheme which integrates the Mobile IP and MPLS protocols by using two‐level hierarchy architecture. Our proposal supports two protocol variants. First, the fast handoff process, which anticipates the LSP procedure set‐up with neighboring locations where a mobile node (MN) may move to, is provided to reduce service disruption. Second, a new mechanism based on the forwarding chain concept is proposed to track efficiently the host mobility within a domain. This concept can significantly reduce registration update costs and provide low handoff latency. Analytical models are developed and simulations are conducted to justify the benefits of our proposed mechanisms. Copyright © 2006 John Wiley & Sons, Ltd.

Mobile IPv6 Security

Mobile IPv6 provides global mobility and location management support for the IPv6 network layer protocol. The design of Mobile IPv6 incorporates security features that differ significantly from its predecessor, Mobile IPv4. Some of the new security features are intended to counter new threats raised by route optimization, while others align Mobile IPv6 security more closely with basic IPv6 security mechanisms. In this paper, we outline the security threats to Mobile IPv6 and describe how the security features of the Mobile IPv6 protocol mitigate them.

DIMINISHING CAPACITY REQUIREMENT FOR MOBILITY DATABASE IN WIRELESS ATM

In wireless ATM, Visitor Location Register (VLR) is the database that supports mobility management. In case the number of roaming users exceeds the VLR supports, the arriving users cannot receive any service. To solve the problem, the Random Replacement (RR) policy randomly selects a victim record in VLR to be replaced with the record of the arriving user. The quality of services for the victim user will certainly drop. Therefore, the proportion of affected users is not allowed to exceed a tolerable threshold. Apparently, VLR size is the key factor of the threshold. The cost for maintaining a VLR increases significantly as its size grows. So, how to utilize the capacity efficiently is an important issue in VLR planning. We propose a Second Chance Replacement (SCR) policy to reduce the requirements for VLR capacity. As compared with the RR policy, the discrete-event simulation results show that the SCR policy can save 2.5% to 28% VLR size under various QoS thresholds.

Backoff strategies for demand re-registration in PCS database failure recovery

Mobility Databases, Home Location Register (HLR) and Visitor Location Register (VLR), are utilized to support mobility management for Mobile Stations (MSs) in Personal Communications Services (PCS) networks. If the location database fail, the subscribers' services will be seriously degraded due to the loss or corruption of location information. Previous work proposed demand re-registration with a p-persistent backoff strategy and a checkpoint method that demonstrates better performance than the periodic re-registration policy. In demand re-registration, after a VLR fails, it broadcasts a re-registration request to all MSs. Backoff strategies are needed since collisions may occur if all MSs try to re-register after receiving the request. Choosing a good backoff strategy for demand re-registration has several benefits that are our goals in this paper. A better strategy will save the re-registration traffic in terms of signaling cost. Moreover, a better strategy will allow an MS to re-register earlier to reduce the probability that a call termination with expensive paging operations happens earlier than location information recovery. In this paper, we propose and study seven backoff strategies for demand re-registration: one optimal p-persistent strategy, three dynamic p-persistent strategies, and three non-persistent strategies. Among these proposed strategies, the optimal p-persistent strategy is optimal in the sense of optimality among all the p-persistent strategies; the three dynamic p-persistent strategies improve p-persistent strategies by allowing the p-value to change with time; the three non-persistent strategies include a binary exponential backoff strategy, an exponential backoff strategy, and a non-exponential non-persistent backoff strategy; our studies show that they can be approximately equivalent to special dynamic p-persistent strategies. Our studies also show that one of the dynamic p-persistent backoff strategies is the best strategy among all the seven proposed strategies and our results indicate that with better backoff strategies, the performance of demand re-registration can be dramatically improved.

An efficient RSVP-mobile IP interworking scheme

During the past years, several attempts have been made to develop functionality for mobility management support and QoS provision in the realm of the IP networks. Since IP was not designed to support such functionality, new protocols have been specified and implemented to tackle these issues. Mobile IP is currently the dominant protocol that allows users to retain connectivity while roaming in IP networks. RSVP (Resource reSerVation Protocol) is a well established protocol for reserving network resources to support QoS requirements. These protocols, when deployed separately, can work quite efficiently. However, if their functionality is combined, several inefficiencies arise in terms of QoS deterioration and misuse of the network resources. To minimize these inefficiencies, we propose a new approach that limits mobility and QoS related network modifications inside the domain, in which a user moves. The deployment of our scheme enhances the network resource usage efficiency, while minimizing the duration of the QoS deterioration experienced after a terminal movement. To quantify the advantages of our proposal, we have developed an analytical and a simulation model that we also present in this paper.

Transport of mobile application part signaling over internet protocol

The convergence of voice, data, and video networks is creating a new environment for telecommunications. In response to the changes, telecommunications equipment manufacturers and service providers are competing fiercely to bring an optimum solution to customers. The evolution of GSM to GPRS and to UMTS is a cellular wireless industry endeavour to meet this demand. This evolution will see the core wireless network infrastructure change from circuit-switched to packet-switched where voice and data are transported using IP as the common protocol. However, this poses a number of challenges, one of which is how to run the key mobile application part signaling protocols over IP. MAP defines the application protocols between switches and databases (e.g., MSC, VLR, SGSN, HLR) for supporting mobility management, security management, radio resource management, and mobile equipment management. UMTS supports both circuit-switched and packet-switched services.

A mobility‐based clustering approach to support mobility management and multicast routing in mobile ad‐hoc wireless networks

AbstractIn our proposed structure, mobile nodes are organized into nonoverlapping clusters which have adaptive variable‐sizes according to their respective mobility. The mobility‐based clustering (MBC) approach we are proposing uses a combination of both physical and logical partitions of the network (i.e. geographic proximity and functional relation between nodes, such as mobility pattern etc.) Copyright © 2001 John Wiley & Sons, Ltd.

Demand re-registration for PCS database restoration

In a Personal Communications Services (PCS) network, mobility databases such as Home Location Register (HLR) and Visitor Location Register (VLR) are utilized to support mobility management for Mobile Stations (MSs). If the location databases fail, the location information loss or corruption will seriously degrade the service offered to the subscribers. In this paper, we propose a new VLR failure recovery scheme called demand re‐registration. In this scheme, the VLR broadcasts a re‐registration request to all MSs after the VLR failure. When an MS receives the re‐registration request, it sends a registration message to the VLR to recover the location record. Since all MSs will re‐register after receiving the broadcasting request, traffic jam (and thus collisions) may occur. If a collision occurs, then the involved MSs must re‐send the registration messages. This paper studies the performance of demand re‐registration by investigating how effectively the re‐registration can recover the location record for an MS before the first MS call termination occurs. Our results indicate that demand re‐registration can effectively recover VLR failure.

Numbers and identities for emerging wireless/PCS networks

In order to support mobility management functions in wireless/PCS networks and provide national and international roaming, well defined, standardized subscriber/terminal numbers and identities are required. Some form of station equipment identities are also needed to ensure that service is denied to non-type-approved or stolen terminals. The article provides an overview of existing standards and current usage of numbers and identities in mobile networks, and their application and planned evolution to support a range of terminal and personal mobility services as PCS networks and services are introduced.

Comparison of signaling loads for PCS systems

We present a comparison of the control signaling load of two vastly different architectures for providing personal communication services (PCSs). One architecture is based on current cellular networks. The other architecture, called the wireless distributed call processing architecture (WDCPA), distributes processing from the mobile switching centers and cell sites and executes new procedures for tracking mobile users and locating mobile users to deliver calls. We determine the signaling load generated within each system to support mobility management and call control based on standard assumptions about the operating parameters of a cellular network. Our results show that, when compared to current cellular systems, for simple single-connection services, WDCPA has marginally reduced cross-network signaling loads. For multiconnection calls, WDCPA incurs 35% less total signaling load for mobility management, has reduced cross-network signaling load for mobility management by up to 65%, and depending on the user model (e.g., data or telecommunication), has reduced total cross-network signaling load, including procedures for call/connection and mobility management, by up to 55% when compared to current cellular systems, while more flexibly supporting services.