Low Power Multi-Hop Networking Analysis in Intelligent Environments

Intelligent systems are driven by the latest technological advances in many different areas such as sensing, embedded systems, wireless communications or context recognition. This paper focuses on some of those areas. Concretely, the paper deals with wireless communications issues in embedded systems. More precisely, the paper combines the multi-hop networking with Bluetooth technology and a quality of service (QoS) metric, the latency. Bluetooth is a radio license-free worldwide communication standard that makes low power multi-hop wireless networking available. It establishes piconets (point-to-point and point-to-multipoint links) and scatternets (multi-hop networks). As a result, many Bluetooth nodes can be interconnected to set up ambient intelligent networks. Then, this paper presents the results of the investigation on multi-hop latency with park and sniff Bluetooth low power modes conducted over the hardware test bench previously implemented. In addition, the empirical models to estimate the latency of multi-hop communications over Bluetooth Asynchronous Connectionless Links (ACL) in park and sniff mode are given. The designers of devices and networks for intelligent systems will benefit from the estimation of the latency in Bluetooth multi-hop communications that the models provide.The research described in this paper was included in AIRHEM IV project and financially supported by the Basque Government Research Program called Elkartek 2015 (code KK_2015/0000085)

Improving forwarding mechanisms for mobile personal area networks

This thesis presents novel methods for improving forwarding mechanisms for personal area networks. Personal area networks are formed by interconnecting personal devices such as personal digital assistants, portable multimedia devices, digital cameras and laptop computers, in an ad hoc fashion. These devices are typically characterised by low complexity hardware, low memory and are usually batterypowered. Protocols and mechanisms developed for general ad hoc networking cannot be directly applied to personal area networks as they are not optimised to suit their specific constraints. The work presented herein proposes solutions for improving error control and routing over personal area networks, which are very important ingredients to the good functioning of the network. The proposed Packet Error Correction (PEC) technique resends only a subset of the transmitted packets, thereby reducing the overhead, while ensuring improved error rates. PEC adapts the number of re-transmissible packets to the conditions of the channel so that unnecessary retransmissions are avoided. It is shown by means of computer simulation that PEC behaves better, in terms of error reduction and overhead, than traditional error control mechanisms, which means that it is adequate for low-power personal devices. The proposed C2HR routing protocol, on the other hand, is designed such that the network lifetime is maximised. This is achieved by forwarding packets through the most energy efficient paths. C2HR is a hybrid routing protocol in the sense that it employs table-driven (proactive) as well as on-demand (reactive) components. Proactive routes are the primary routes, i.e., packets are forwarded through those paths when the network is stable; however, in case of failures, the protocol searches for alternative routes on-demand, through which data is routed temporarily. The advantage of C2HR is that data can still be forwarded even when routing is re-converging, thereby increasing the throughput. Simulation results show that the proposed routing method is more energy efficient than traditional least hops routing, and results in higher data throughput. C2HR relies on a network leader for collecting and distributing topology information, which in turn requires an estimate of the underlying topology. Thus, this thesis also proposes a new cooperative leader election algorithm and techniques for estimating network characteristics in mobile environments. The proposed solutions are simulated under various conditions and demonstrate appreciable behaviour

Communication protocols for energy constrained networks

Ph.DDOCTOR OF PHILOSOPH

A cooperative communication protocol for wireless ad-hoc networks

Thesis (M. Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 59-61).This thesis presents the design and implementation of a communication protocol that utilizes local cooperation among nodes to efficiently transfer data. Multi-hop routing in ad-hoc wireless networks realizes some scalability benefits over direct transmission by utilizing cooperation in the network layer, where all nodes act as routers to relay messages. Cooperative transmission takes this idea a step further, moving cooperation to the link layer, where nodes actually broadcast signals simultaneously to increase signal strength. Using network topology information derived from propagation delay measurement, nodes dynamically establish and update membership in rebroadcasting cells. Rebroadcast cells use constructively interfering modulation schemes to broadcast radio signals together, directing an amplified signal toward the intended recipient. This results in a link-layer routing system well suited to real-time data streaming in mobile, ad-hoc, wireless networks.by Jeremy I. Silber.M.Eng.and S.B

Multi-hop wireless relay using Bluetooth specification

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 85-87).This thesis presents BlueRelay, a novel protocol that extends the Bluetooth specification to support multi-hop wireless communication. Bluetooth is a wireless communication protocol originally designed for point-to-point communication within a small network called a piconet, where a master has centralized coordination over slave devices. The purpose of BlueRelay is to enable inter-piconet communication using existing Bluetooth mechanisms without any modifications to the Bluetooth link layer and its medium access control protocol. BlueRelay is a two-part protocol. First, the relay establishment process details how a slave device establishes communications with two master devices and acts as a forwarding node between two piconets. Second, the piconet switching scheme employs a Bluetooth mechanism called the HOLD mode to enable a slave to switch back and forth between two piconets. These two techniques allow Bluetooth devices to forward packets over multiple hops and beyond the communication range of the source's transmitter. BlueRelay is simulated in a Bluetooth simulator that was developed by IBM to simulate the Bluetooth protocol stack. By simulating the relay establishment process and the piconet switching scheme in the Bluetooth simulator, we demonstrate that multi-hop wireless communication can be achieved using the existing mechanisms of the Bluetooth specification. Simulation results show that relay establishment occurs under 10 seconds and a maximum of 300 kbps average throughput can be achieved for multi-hop wireless communication. End-to-end latency ranges from 15ms per hop to 300ms per hop, depending on the HOLD period.by Richard K. Moy.M.Eng

Distributed algorithms for dynamic topology construction and their applications

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 155-162).(cont.) of piconets is close to optimal, and any device is a member of at most two piconets.We introduce new distributed algorithms that dynamically construct network topologies. These algorithms not only adapt to dynamic topologies where nodes join and leave, but also actively set up and remove links between the nodes, to achieve certain global graph properties. First, we present a novel distributed algorithm for constructing overlay networks that are composed of d Hamilton cycles. The protocol is decentralized as no globally-known server is required. With high probability, the constructed topologies are expanders with O(logd n) diameters and ... second largest eigenvalues. Our protocol exploits the properties of random walks on expanders. A new node can join the network in O(logd n) time with O(dlogd n) messages. A node can leave in O(1) time with O(d) messages. Second, we investigate a layered construction of the random expander networks that can implement a distributed hash table. Layered expanders can achieve degree-optimal routing at O(log n/log log n) time, where each node has O(log n) neighbors. We also analyze a self-balancing scheme for the layered networks. Third, we study the resource discovery problem, in which a network of machines discover one another by making network connections. We present two randomized algorithms to solve the resource discovery problem in O(log n) time. Fourth, we apply the insight gained from the resource discovery algorithms on general networks to ad hoc wireless networks. A Bluetooth ad hoc network can be formed by interconnecting piconets into scatternets. We present and analyze a new randomized distributed protocol for Bluetooth scatternet formation. We prove that our protocol achieves O(log n) time complexity and O(n) message complexity. In the scatternets formed by our protocol, the numberby Ching Law.Ph.D

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

Colocation aware content sharing in urban transport

People living in urban areas spend a considerable amount of time on public transport. During these periods, opportunities for inter-personal networking present themselves, as many of us now carry electronic devices equipped with Bluetooth or other wireless capabilities. Using these devices, individuals can share content (e.g., music, news or video clips) with fellow travellers that happen to be on the same train or bus. Transferring media takes time; in order to maximise the chances of successfully completing interesting downloads, users should identify neighbours that possess desirable content and who will travel with them for long-enough periods. In this thesis, a peer-to-peer content distribution system for wireless devices is proposed, grounded on three main contributions: (1) a technique to predict colocation durations (2) a mechanism to exclude poorly performing peers and (3) a library advertisement protocol. The prediction scheme works on the observation that people have a high degree of regularity in their movements. Ensuring that content is accurately described and delivered is a challenge in open networks, requiring the use of a trust framework, to avoid devices that do not behave appropriately. Content advertising methodologies are investigated, showing their effect on whether popular material or niche tastes are disseminated. We first validate our assumptions on synthetic and real datasets, particularly movement traces that are comparable to urban environments. We then illustrate real world operation using measurements from mobile devices running our system in the proposed environment. Finally, we demonstrate experimentally on these traces that our content sharing system significantly improves data communication efficiency, and file availability compared to naive approaches

A Quantitative Analysis of Performance in a Multi-Protocol Ad Hoc 802.11b-based Wireless Local Network

The popularity of the Internet and the growing demand for ubiquitous connectivity accelerate the need for viable wireless local area network (WLAN) solutions. As a consequence, increasing number of manufacturers have adopted the Institute of Electrical and Electronic Engineers (IEEE) 802.11a/b/g set of WLAN standards and produced inexpensive wireless products to expand capabilities of existing LANs. IEEE 802.11 b wireless products are widely accepted. Mobile ad hoc networks, a variant of the 802.11 standards, exist without the requirement for a wired infrastructure or host to provide routing, connectivity, and maintenance services. Because of the high variability of environments in which ad hoc networks operate, numerous routing protocols are proposed. Research indicates that these protocols are unsuited for efficient operation in multiple environments. In this investigation, the author examined the effect of multiple protocols on throughput and end-to-end delay in simulated ad hoc networks. The author selected the ad hoc on-demand distance vector (AODV) and dynamic source routing (DSR) routing protocols for this research. The outcomes from the simulations conducted indicated increased end-to-end delay and reduced packet throughput as a result of the mixed populations of the AODV and DSR ad hoc routing protocols. The results also indicated that increasing node density and velocity improved packet throughput and reduced end-to-end delay

Smart Wireless Sensor Networks

The recent development of communication and sensor technology results in the growth of a new attractive and challenging area - wireless sensor networks (WSNs). A wireless sensor network which consists of a large number of sensor nodes is deployed in environmental fields to serve various applications. Facilitated with the ability of wireless communication and intelligent computation, these nodes become smart sensors which do not only perceive ambient physical parameters but also be able to process information, cooperate with each other and self-organize into the network. These new features assist the sensor nodes as well as the network to operate more efficiently in terms of both data acquisition and energy consumption. Special purposes of the applications require design and operation of WSNs different from conventional networks such as the internet. The network design must take into account of the objectives of specific applications. The nature of deployed environment must be considered. The limited of sensor nodes� resources such as memory, computational ability, communication bandwidth and energy source are the challenges in network design. A smart wireless sensor network must be able to deal with these constraints as well as to guarantee the connectivity, coverage, reliability and security of network's operation for a maximized lifetime. This book discusses various aspects of designing such smart wireless sensor networks. Main topics includes: design methodologies, network protocols and algorithms, quality of service management, coverage optimization, time synchronization and security techniques for sensor networks