Mobile ad-hoc networking involves peer-to-peer communication in a network with a dynamically changing topology. Achieving energy efficient communication in such a network is more challenging than in cellular networks since there is no centralized arbiter such as a base station that can administer power management. We propose and evaluate a power control loop, similar to those commonly found in cellular CDMA networks, for ad-hoc wireless networks. We use a comprehensive simulation infrastructure consisting of group mobility, group communication and terrain blockage models. A major focus of research in ad-hoc wireless networking is to reduce energy consumption because the wireless devices are envisioned to have small batteries and be incapable of energy scavenging. We show that this power control loop reduces energy consumption per transmitted byte by 10-20%. Furthermore, we show that it increases overall throughput by 15%.

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Distributed power control in ad-hoc wireless networks

The field of wireless and mobile communication has a remarkable history that spans over a century of technology innovations from Marconi's first transatlantic transmission in 1899 to the worldwide adoption of cellular mobile services by over four billion people today. Wireless has become one of the most pervasive core technology enablers for a diverse variety of computing and communications applications ranging from third-generation/fourth-generation (3G/4G) cellular devices, broadband access, indoor WiFi networks, vehicle-to-vehicle (V2V) systems to embedded sensor and radio-frequency identification (RFID) applications. This has led to an accelerating pace of research and development in the wireless area with the promise of significant new breakthroughs over the next decade and beyond. This paper provides a perspective of some of the research frontiers of wireless and mobile communications, identifying early stage key technologies of strategic importance and the new applications that they will enable. Specific new radio technologies discussed include dynamic spectrum access (DSA), white space, cognitive software-defined radio (SDR), antenna beam steering and multiple-input-multiple-output (MIMO), 60-GHz transmission, and cooperative communications. Taken together, these approaches have the potential for dramatically increasing radio link speeds from current megabit per second rates to gigabit per second, while also improving radio system capacity and spectrum efficiency significantly. The paper also introduces a number of emerging wireless/mobile networking concepts including multihoming, ad hoc and multihop mesh, delay-tolerant routing, and mobile content caching, providing a discussion of the protocol capabilities needed to support each of these usage scenarios. In conclusion, the paper briefly discusses the impact of these wireless technologies and networking techniques on the design of emerging audiovisual and multimedia applications as they migrate to mobile Internet platforms.

Frontiers of Wireless and Mobile Communications

The growth of wireless networking is enabling many Internet hosts to become mobile. This article describes and compares three alternatives for providing host mobility managment in IP-based networks. We first summarize the operation and behavior of Mobile IP, on which the Internet Engineering Task Force has focused as a host mobility solution. We next describe two alternative architectures (Migrate and host identity protocol) for providing mobility management. Our qualitative comparison focuses on contrasting the different performance, security, deployment, scalability, and robustness properties of each approach.

Host mobility for IP networks: a comparison

Realistic models for node movement are essential in simulating mobile ad hoc networks. Many MANET scenarios are most realistically represented using group movement, but existing group movement models depict individual group members as independent actors moving randomly. For many scenarios however, group movement implies a common goal or orientation, and hence an inherent structure to the group. We show that this structure can be defined a-priori, and that knowledge of it will result in more accurate simulations. This paper presents the Structured Group Mobility Model~(SGMM), which parameterizes group structure and generates movement sequences for use in simulations. We define the model and demonstrate how such a model of node mobility may be used in creating simulations of several MANET scenarios. We compare simulations using the SGMM with other models using various routing algorithms. Our preliminary results indicate that accurate representation of group structure has a significant effect on the overall simulation, particularly in the area of link stability. The results also imply the need for routing algorithms that take group structure into account.

A structured group mobility model for the simulation of mobile ad hoc networks

The host identity protocol (HIP) is a recent protocol proposal for secure host mobility and multihoming using cryptographic-based name space for Internet hosts. This paper reports on our experience with implementing HIP and experimenting with it as a mobility management and host multihoming solution. After first introducing the HIP approach and contrasting it with other solutions, we describe our approach for implementing HIP as an extension to Linux and FreeS/WAN IPsec, including our use and extension of standard APIs. We then characterize the performance of HIP packet exchanges experimentally, and report that the computational overhead is dominated by the DSA signing of the HIP packets. Using 266 MHz Pentium II-based laptops, our HIP implementation took slightly under 1 second on average to complete connection setup, and less than 200 ms to process a mobility-initiated readdress. We also characterize the overhead due to the HIP "cookie challenge" used for stateless connection setup. We conclude by identifying areas for continued HIP development.

Experience with the host identity protocol for secure host mobility and multihoming

The mobile IP (MIP) protocol for IP version 4 provides continuous Internet connectivity to mobile hosts. However, currently it has some drawbacks in the areas of survivability, performance, interoperability with protocols for providing QoS. We have proposed an alternative protocol, mobile IP with location registers (MIP-LR), which overcomes some of these drawbacks and is closer to the "service node" database approach used in the public switched telephone network (PSTN): before launching a packet to the mobile host, the sender first queries a database, called the home location register (HLR), to obtain the recipient's current location. MIP-LR is designed for operation in enterprise environments or within logical administrative domains. We focus on showing how MIP-LR enhances the survivability of MIP by eliminating some of the functions which MIP introduces for mobility support, allowing the HLR to be placed outside the mobile's home network in case the latter is particularly vulnerable, and replicating and distributing HLRs. We present two schemes for managing the multiple HLRs and enabling mobile and correspondent hosts to dynamically discover the addresses of the HLRs serving a given mobile host. The first scheme introduces a set of translation server (TS) databases while the second uses a form of quorum consensus based on the triangle lattice (TL); for the latter we present an enhanced protocol called the optimistic TL(OTL). For both schemes we present algorithms for mobile host registration and packet delivery, protocols for recovery from HLR failures, and complexity analysis of the overhead involved.

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Enhancing survivability of mobile Internet access using mobile IP with location registers

The mobile internetworking protocol or mobile IP, proposed in the Internet Engineering Task Force (IETF), does not consider the requirements of tactical military networks, which are predominantly radio based and "on the move" with minimal fixed infrastructure. We present a tactical mobile IP solution for the military architecture, specifically the radio access point (RAP) network, with a focus on providing mobility and fault tolerance. Our approach, in this work, is on improving survivability by moving mobility agents to higher, less mobile and more fault tolerant echelons in the hierarchy. As a baseline approach, we propose a tactical mobile IP solution based on the mobile IP protocol proposed in the IETF using Class C address assignment. It is observed that an architecture with multiple Class C address assignment supports basic mobile IP operation without any modification. We propose the use of classless inter-domain routing (CIDR) to accommodate a large number of Internet addresses. It is shown that other address assignment schemes can also be applied to the military architecture without any modification to the mobile IP. Three route optimization schemes are also described to improve the performance of datagram routing to mobile nodes.

M. Bereschinsky

Papers

Enhancing survivability of mobile Internet access using mobile IP with location registers

Application of mobile IP to tactical mobile internetworking