Wireless access to Internet services will become typical, rather than the exception as it is today. Such a vision presents great demands on mobile networks. Mobile IP represents a simple and scalable global mobility solution but lacks the support for fast handoff control and paging found in cellular telephony networks. In contrast, second- and third-generation cellular systems offer seamless mobility support but are built on complex and costly connection-oriented networking infrastructure that lacks the inherent flexibility, robustness, and scalability found in IP networks. In this article we present Cellular IP, a micro-mobility protocol that provides seamless mobility support in limited geographical areas. Cellular IP, which incorporates a number of important cellular system design principles such as paging in support of passive connectivity, is built on a foundation of IP forwarding, minimal signaling, and soft-state location management. We discuss the design, implementation, ...

This paper investigates differentiated services in wireless packet networks using a fully distributed approach that supports service differentiation, radio monitoring, and admission control. While our proposal is generally applicable to distributed wireless access schemes, we design, implement, and evaluate our framework within the context of existing wireless technology. Service differentiation is based on the IEEE 802.11 Distributed Coordination Function (DCF) originally designed to support best-effort data services. We analyze the delay experienced by a mobile host implementing the IEEE 802.11 DCF and derive a closed-form formula.We then extend the DCF to provide service differentiation for delay-sensitive and best-effort traffic based on the results from the analysis. Two distributed estimation algorithms are proposed. These algorithms are evaluated using simulation, analysis, and experimentation. A Virtual MAC (VMAC) algorithm passively monitors the radio channel and estimates locally achievable service levels. The VMAC estimates key MAC level statistics related to service quality such as delay, delay variation, packet collision, and packet loss. We show the efficiency of the VMAC algorithm through simulation and consider significantly overlapping cells and highly bursty traffic mixes. In addition, we implement and evaluate the VMAC in an experimental differentiated services wireless testbed. A Virtual Source (VS) algorithm utilizes the VMAC to estimate application -level service quality. The VS allows application parameters to be tuned in response to dynamic channel conditions based on "virtual delay curves." We demonstrate through simulation that when these distributed virtual algorithms are applied to the admission control of the radio channel then a globally st...

The IETF Mobile IP Working Group is discussing a number of enhancements to the base protocol to reduce the latency, packet loss and signaling overhead experienced during hand-off. bz this article, we discuss a number of "micro-mobility protocols " that extend Mobile IP with fast handoff and paging capabilities. The aim of this article is not to provide an ex-haustive survey of these protocols. Rather, we discuss the motivation behind micfv-mobility, present common characteristics that a number of proposals share and briefly describe some of the key contributions discussed by the working group. In the longer tetwt there is a need to understand the differences between many of the micro-mobility proposals discussed in this article in terms of complexity of the design choice, and performance di~emnces. As part of that process we have recently made available the Columbia Micro-mobility Suite (CMS). The CMS software is freely available from the web (comet.columbia.edu/micromobility) and includes ns source code extensions for Celhdar IP, Hawaii and Hierarchical Mobile IP. I.

This paper assesses the state-of-the-art in Quality-of-Service (QoS) adaptive wireless networks and proposes new adaptation techniques that better suit application specific needs. The contribution of the paper is as follows: we propose an adaptive service comprising (i) bandwidth utility functions, which capture the adaptive nature of mobile applications in terms of the range of bandwidth over which they prefer to operate; and (ii) adaptation scripts, which enable adaptive mobile applications to program the per-flow adaptation time scale and bandwidth granularity realizing application-specific adaptive services. To maintain adaptive services in wireless packet access networks, we propose a split level adaptation control framework that operates at the network and application levels. Network level control employs a periodic probing mechanism between mobile devices and network gateways in support of utility based max--min fair resource allocation. Application level control is managed by a set of distributed adaptation handlers that operate at mobile devices realizing application-specific adaptation strategies.

In this paper, the effect of spatial diversity on the throughput and reliability of wireless networks is examined. Spatial diversity is realized through multiple independently fading transmit/receive antenna paths in single-user communication and through independently fading links in multiuser communication. Adopting spatial diversity as a central theme, we start by studying its information-theoretic foundations, then we illustrate its benefits across the physical (signal transmission/coding and receiver signal processing) and networking (resource allocation, routing, and applications) layers. Throughout the paper, we discuss engineering intuition and tradeoffs, emphasizing the strong interactions between the various network functionalities.

This article first surveys existing protocols for supporting IP mobility and then proposes an extension to the Mobile IP architecture, called TeleMIP. Our architecture attempts to achieve smaller handoff latency by localizing the scope of most location update messages within an administrative domain or a geographical region. TeleMIP is intended for use in evolving third-generation wireless networks, and introduces a new logical entity, called the mobility agent, which provides a mobile node with a stable point of attachment in a foreign network. While the MA is functionally similar to conventional foreign agents, it is located at a higher level in the network hierarchy than the subnet-specific FA. Location updates for intradomain mobility are localized only up to the MA; transmission of global location updates are necessary only when the mobile changes administrative domains and/or geographical regions. By permitting the use of private or locally scoped addresses for handling intradomain mobility, TeleMIP allows efficient use of public address space. Also, by reducing the frequency of global update messages, our architecture overcomes several drawbacks of existing protocols, such as large latencies in location updates, higher likelihood of loss of binding update messages, and loss of inflight packets, and thus provides better mobility support for real-time services and applications. The dynamic creation of mobility agents (in TeleMIP) permits the use of load balancing schemes for the efficient management of network resources.

Zhu, Senior Member, IEEE Roaming across heterogeneous wireless networks such as wireless wide area network (WWAN) and wireless local area network (WLAN) poses considerable challenges, as it is usually difficult to maintain the existing connections and guarantee the necessary quality of service (QoS). This paper proposes a novel seamless and proactive end-to-end mobility management system, which can maintain the connections based on the end-to-end principle by incorporating an intelligent network status detection mechanism. The proposed system consists of two components, Connection Manager (CM) and Virtual Connectivity (VC). The CM, by using novel Media Access Control (MAC)-layer and physical-layer sensing techniques, can obtain accurate network condition while at the same time reducing the unnecessary handoff and ping-pong effect. The VC, can make mobility transparent to applications without additional network-layer infrastructure support using a Local Connection Translation (LCT), and can handle mobility well in Network Address Translator (NAT) and simultaneous movement cases using a Subscription/Notification (S/N) service. The proposed system enjoys several unique advantages: 1) capable of reacting to roaming events proactively and accurately; 2) maintaining the connection’s continuity with small handoff delay; and 3) being a unified end-to-end approach for both IPv4 and IPv6 networks. We have built a prototype system and performed experiments to demonstrate the advantages of the proposed system. Index Terms-WWAN/WLAN handoff, network condition detection, mobility management.

Ever increasing data traffic and limited capacity are major causes for congestion in current cellular systems. This paper presents a new architecture for the next generation wireless systems based on the integration of the cellular infrastructure and modern Ad-hoc relaying technologies. The new architecture can efficiently balance traffic loads between cells by using Ad-hoc relay stations (ARS) to relay traffic from one cell to another cell dynamically. This can not only increase a system's capacity cost-effectively, but also reduce transmission power for mobile hosts, and provide services for shadow areas. In this paper, we present the architectural concept including its basic operations and principle benefits. We also propose a seed-growing approach for ARS placement, and discuss the upper boundon the number of seed ARS's needed in the system. We evaluate the performance improvement of the new architecture through analysis and simulations. 1 Introduction Ever increasing data traffi...

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The next generation of mobile networks will utilise multiple radio access technologies. These heterogeneous wireless networks will enable the user to seamlessly roam between the different access technologies to maintain network connectivity and satisfactory QoS. Network operators will be able to select an access network on the arrival of a new call or handover request. Selecting the most optimal connection and controlling access to the available networks is an important consideration for overall network stability and providing guaranteed QoS. In this paper we propose an intelligent call admission control and mobility management architecture using policy-based management. A call admission policy admits a new user based on the current load and a predefined service mix. A network health monitor continuously updates the residual capacity by observing the quality of the current connections. The mobility management policy focuses on handover control between the available access networks. Mobiles can be selected for forced handover when a network reaches a congested state. A selection policy controls the mobile selection procedure. 1