How much information can be carried over a wireless network with a multiplicity of nodes? What are the optimal strategies for information transmission and cooperation among the nodes? We obtain sharp information theoretic scaling laws under some conditions.

Motivated by the poor experimental scaling reported in a study of the performance of ad hoc networks in [15], we propose a new protocol for media access control in ad hoc networks. Our protocol seeks to avoid collisions without making explicit reservations for each and every packet. The key idea is to employ a random schedule which is driven by a pseudo-random number generator. By exchanging the seeds of their pseudo-random number generators within a two-hop neighborhood, the nodes effectively publish their schedules to all hidden as well as exposed nodes. This allows each node to opportunistically choose transmission slots. This scheme can also be employed during the reservation phase of a protocol such as IEEE 802.11. Throughput calculations and simulation results are presented.

Mobile ad hoc networks (MANET) are becoming an integral part of the ubiquitous computing and communication environment, providing new infrastructure for multimedia applications such as video phone, multimedia-on-demand, and others. In order to access multimedia information in MANET, Quality of Service (QoS) needs to be considered, such as high success rate to access multimedia data, bounded end-to-end delay, and others. In this paper, we present a data accessibility service for a group of mobile users to access desired data with high success rate. This accessibility service is only possible if we utilize advanced data advertising, lookup and replication services, as well as a novel predictive location-based QoS routing protocol in an integrated fashion. Using cross-layer design, we illustrate how the QoS routing protocol assists data advertising, lookup and replication services to achieve high data access success rate. Simulation results have shown that our design is successful in a dynamic MANET.

Introduction The Panel on Future Directions in Control, Dynamics, and Systems was formed in April 2000 to provide a renewed vision of future challenges and opportunities in the field, along with recommendations to government agencies, universities, and research organizations to ensure continued progress in areas of importance to the industrial and defense base. Its report was released in April 2002 and will be published by SIAM [1]. The intent of the report is to raise the overall visibility of research in control, highlight its importance in applications of national interest, and indicate some of the key trends that are important for continued vitality of the field. The panel was chaired by Professor Richard Murray (Caltech) and was formed with the help of an organizing committee consisting of Prof. Roger Brockett (Harvard), Prof. John Burns (VPI), Prof. John Doyle (Caltech) and Dr. Gunter Stein (Honeywell). The remaining panel members are Karl Astrom (Lund Institute of Technology),

We present two protocols for ad hoc wireless networks, one for the media access control problem, and the other for the power control problem. For the media access control problem we...

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In this paper, we study the connectivity properties of a wireless sensor network from an information-theoretic viewpoint. We consider both regular linear (one-dimensional) and planar (two-dimensional) networks with unreliable sensor nodes, i.e., each node is inactive/dead with a certain probability. We study the following problems: 1) What is the fundamental limit on the data rate that such a network can support for a single sensor node to the destination under transmission power and network-topology constraints? 2) What are the constraints on the network topology such that any (single) sensor can communicate with the destination at a desired rate? For problem 1), we provide upper and lower bounds on the achievable data rate, and for problem 2), we provide upper and lower bounds on the distance between the nodes required for communication at the desired rate.

Abstract — For energy-constrained wireless networks of sensors and actuators, selection of links with high packet success rate helps to ensure reliable long-term operation. During the implementation of a protocol targeting industrial applications of such systems, it was found that it is advantageous to acquire accurate information about the availability and quality of the RF communication links prior to the network topology formation. Link assessment as part of the initialization process, accomplishes this task by assessing a sufficient number of packets exchanged between neighboring nodes. This paper introduces and analyzes two different link assessment methods: First, a random scheme is evaluated. It allows for a probabilistic guarantee of collision-free packet exchange. Next, a general method is described which employs ‘constant-weight codes ’ and provides a deterministic guarantee of success. In particular, a special class of constant-weight codes which are cyclically permutable (also known as optical orthogonal codes), are considered. It is shown that due to additional properties of these codes, they make the link assessment process simpler, and therefore they are preferred over other codes. Different methods are compared based on their energy/time requirements, and implementation complexity. I.

The global communications system today (the telephone system yesterday) is considered as the largest man-made system all categories. While the demand for increased bandwidth in such systems increases, an increased interest in utilizing the available resources efficiently can be observed. Here, the subset of wireless cellular communications systems will be in focus and methods for transmitter power control.

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