Mobile ad hoc networks (MANETs) represent complex distributed systems that comprise wireless mobile nodes that can freely and dynamically self-organize into arbitrary and temporary, ‘‘ad-hoc’’ network topologies, allowing people and devices to seamlessly internetwork in areas with no pre-existing communication infrastructure, e.g., disaster recovery environments. Ad hoc networking concept is not a new one, having been around in various forms for over 20 years. Traditionally, tactical networks have been the only communication networking application that followed the ad hoc paradigm. Recently, the introduction of new technologies such as the Bluetooth, IEEE 802.11 and Hyperlan are helping enable eventual commercial MANET deployments outside the military domain. These recent evolutions have been generating a renewed and growing interest in the research and development of MANET. This paper attempts to provide a comprehensive overview of this dynamic field. It first explains the important role that mobile ad hoc networks play in the evolution of future wireless technologies. Then, it reviews the latest research activities in these areas, including a summary of MANETs characteristics, capabilities, applications, and design constraints. The paper concludes by presenting a set of challenges and problems requiring further research in the future. � 2003 Elsevier B.V. All rights reserved.

/pdf/mobile-ad-hoc-networking-imperatives-and-challenges-56mord86q0.pdf

Mobile ad hoc networking: imperatives and challenges

In spite of the massive efforts in researching and developing mobile ad hoc networks in the last decade, this type of network has not yet witnessed mass market deployment. The low commercial penetration of products based on ad hoc networking technology could be explained by noting that the ongoing research is mainly focused on implementing military or specialized civilian applications. On the other hand, users are interested in general-purpose applications where high bandwidth and open access to the Internet are consolidated and cheap commodities. To turn mobile ad hoc networks into a commodity, we should move to more pragmatic "opportunistic ad hoc networking" in which multihop ad hoc networks are not isolated self-configured networks, but rather emerge as a flexible and low-cost extension of wired infrastructure networks coexisting with them. Indeed, a new class of networks is emerging from this view: mesh networks. This article provides an overview of mesh networking technology. In particular, starting from commercial case studies we describe the core building blocks and distinct features on which wireless mesh networks should be based. We provide a survey of the current state of the art in off-the-shelf and proprietary solutions to build wireless mesh networks. Finally, we address the challenges of designing a high-performance, scalable, and cost-effective wireless mesh network.

Mesh networks: commodity multihop ad hoc networks

The growing interest in mobile ad hoc network techniques has resulted in many routing protocol proposals. Scalability issues in ad hoc networks are attracting increasing attention these days. We survey the routing protocols that address scalability. The routing protocols included in the survey fall into three categories: flat routing protocols; hierarchical routing approaches; GPS augmented geographical routing schemes. The article compares the scalability properties and operational features of the protocols and discusses challenges in future routing protocol designs.

/pdf/scalable-routing-protocols-for-mobile-ad-hoc-networks-5g9vhzi0lx.pdf

Scalable routing protocols for mobile ad hoc networks

One of the most vibrant and active \" new \" fields today is that of ad hoc networks. Within the past few years the field has seen o rapid expansion of visibility and work due to the proliferation of inexpensive, widely available wireless devices and the network community's interest in mobile computing. ne of the most vibrant and active \" new \" fields today is that of ad hoc networks. Significant research in this area has been ongoing for nearly 30 years, also under the names packet radio or multi-hop networks. Within the past few years, though, the field 0 has seen a rapid expansion of visibility and work due to the proliferation of inexpensive, widely available wireless devices and the network community's interest in mobile computing. An ad hoc network is a (possibly mobile) collection of communications devices (nodes) that wish to communicate, but have no fixed infrastructure available, and have no predetermined organization of available links. Individual nodes are responsible for dynamically discovering which other nodes they can directly communicate with. A key assumption is that not all nodes can directly communicate with each other, so nodes are required t o relay packets on behalf of other nodes in order to deliver data across the network. A significant feature of ad hoc networks is that rapid changes in connectivity and link characteristics are introduced due to node mobility and power control practices. Ad hoc networks can be built around any wireless technology, including infrared and radio frequency (RF). Ad hoc networking is a multi-layer problem. The physical layer must adapt to rapid changes in link characteristics. The multiple access control (MAC) layer needs to minimize collisions, allow fair access, and semi-reliably transport data over the shared wireless links in the presence of rapid changes and hidden or exposed terminals. The network layer needs to determine and distribute information used to calculate paths in a way that maintains efficiency when links change often and bandwidth is at a premium. It'also needs to integrate smoothly with traditional , non ad hoc-aware internetworks and perform functions such as auto-configuration in this changing environment. The transport layer must be able to handle delay and packet loss statistics that are very different than wired networks. Finally, applications need to be designed to handle frequent disconnection and reconnec-tion with peer applications as well as widely varying delay and packet loss characteristics. Ad hoc networks …

A brief overview of ad hoc networks: challenges and directions

We analyze an architecture based on mobility to address the problem of energy efficient data collection in a sensor network. Our approach exploits mobile nodes present in the sensor field as forwarding agents. As a mobile node moves in close proximity to sensors, data is transferred to the mobile node for later depositing at the destination. We present an analytical model to understand the key performance metrics such as data transfer, latency to the destination, and power. Parameters for our model include: sensor buffer size, data generation rate, radio characteristics, and mobility patterns of mobile nodes. Through simulation we verify our model and show that our approach can provide substantial savings in energy as compared to the traditional ad-hoc network approach.

/pdf/exploiting-mobility-for-energy-efficient-data-collection-in-2vcp66dexg.pdf

Exploiting mobility for energy efficient data collection in wireless sensor networks

In this paper, we introduce a class of approaches that attempt to scale link-state routing by limiting the scope of link state update dissemination in space and over time We present the first fundamental analysis of this generic class, which we call "Fuzzy Sighted Link State routing" Using a novel perspective on the "overhead"of a protocol that includes not only the overhead due to control messages but also due to route sub-optimality, we formulate an analytical model whose solution automatically leads to the best algorithm in this class This algorithm is shown to have nearly the best possible asymptotic overhead for any routing algorithm -proactive or reactive Simulation results are presented that compare the performance or several algorithms in this class

Making link-state routing scale for ad hoc networks

A novel framework is presented for the study of scalability in ad hoc networks. Using this framework, the first asymptotic analysis is provided with respect to network size, mobility, and traffic for each fundamental class of ad hoc routing algorithms. Protocols studied include the following: plain flooding (PF), standard link state (SLS), dynamic source routing (DSR), hierarchical link state (HierLS), zone routing protocol (ZRP), and hazy sighted link state (HSLS). It is shown that PF and ZRP scale better with mobility, SIJS and ZRP scale better with respect to traffic, and HSLS scales better with respect to network size. The analysis provides deeper understanding of the limits and trade-offs inherent in mobile ad hoc network routing. Our analysis is complemented with a simulation experiment comparing HSLS and HierLS. An important contribution of this paper is that HSLS is an scalable, easy-to-implement, alternative to hierarchical approaches for large ad hoc networks.

/pdf/on-the-scalability-of-ad-hoc-routing-protocols-11ga85nesv.pdf

On the scalability of ad hoc routing protocols

We consider the concept of opportunistic spectrum access (OSA) -- whereby radios identify unused portions of licensed spectrum, and utilize that spectrum without adverse impact on the primary licensees. OSA allows both dramatically higher spectrum utilization and near-zero deployment time, with an obvious and significant impact on both civilian and military communications. We discuss two broad classes of challenges to OSA: spectrum agility, which involves wideband sensing, opportunity identification, coordination and use; and policy agility, which enables regulatory policies to be applied dynamically using machine understandable policies. Focusing on spectrum agility, we present an architecture based on an OSA adaptation layer. We describe protocols for OSA, including a hole information protocol, idle channel selection and use, and an access protocol for the coordination channel. We present a simulation study, discuss insights, and show that even a simple protocol for opportunistic spectrum allocation can provide an order-of-magnitude performance improvement in throughput over a legacy system.

Opportunistic spectrum access: challenges, architecture, protocols

A method ( 508 ) and system ( 226 ) provide directional medium access control for wireless nodes ( 102 ) in a wireless network ( 100 ), each of the nodes ( 102 ) having a transceiver ( 228 ) and a plurality of antennas ( 232, 234, 236, 238, 240 ) in selective communication with the transceiver ( 228 ). Packets ( 202 ) are transmitted from a transmitting node ( 106 ) of the nodes ( 102 ) when a channel ( 104 ) is sensed as being free in a beam direction of a selected one of the antennas ( 232, 234, 236, 238, 240 ), and in accordance with a pre-determined transmission mode ( 304 ) for the data packet ( 202 ). The transmitting node ( 106 ) is periodically placed in a forced idle state, thereby being prevented from transmitting data packets ( 202 ), but being able to receive and respond to data packets ( 202 ) from other nodes ( 102 ).

Directional carrier sense medium access for wireless nodes

The invention relates generally to systems, methods and/or devices for joining, generating, maintaining, and/or multicasting information via a multicast mesh.

Cesar A. Santivanez

Papers

Making link-state routing scale for ad hoc networks

On the scalability of ad hoc routing protocols

Opportunistic spectrum access: challenges, architecture, protocols

Directional carrier sense medium access for wireless nodes

Methods for wireless mesh multicasting