Self-organizing Bluetooth scatternets

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.Includes bibliographical references (p. 71-73).There is increasing interest in wireless ad hoc networks built from portable devices equipped with short-range wireless network interfaces. This thesis addresses issues related to internetworking such networks to form larger "scatternets." Within the constraints imposed by the emerging standard Bluetooth link layer and MAC protocol, we develop a set of online algorithms to form scatternets and to schedule point-to-point communication links. Our efficient online topology formation algorithm, called TSF (Tree Scatternet Formation), builds scatternets by connecting nodes into a tree structure that simplifies packet routing and scheduling. Unlike earlier works, our design does not restrict the number of nodes in the scatternet, and also allows nodes to arrive and leave at arbitrary times, incrementally building the topology and healing partitions when they occur. We have developed a Bluetooth simulator in ns which includes most aspects of the entire Bluetooth protocol stack. It was used to derive simulation results that show that TSF has low latencies in link establishment, tree formation and partition healing. All of these grow logarithmically with the number of nodes in the scatternet. Furthermore, TSF generates tree topologies where the average path length between any node pair grows logarithmically with the size of the scatternet. Our scheduling algorithm, called TSS (Tree Scatternet Scheduling), takes advantage of the tree structure of the scatternets constructed by TSF. Unlike previous works, TSS coordinates one-hop neighbors effectively to increase the overall performance of the scatternet. In addition, TSS is robust and responsive to network conditions, adapting the inter-piconet link schedule effectively based on varying workload conditions. We demonstrate that TSS has good performance on throughput and latency under various traffic loads.by Godfrey Tan.S.M

A survey on Bluetooth multi-hop networks

Bluetooth was firstly announced in 1998. Originally designed as cable replacement connecting devices in a point-to-point fashion its high penetration arouses interest in its ad-hoc networking potential. This ad-hoc networking potential of Bluetooth is advertised for years - but until recently no actual products were available and less than a handful of real Bluetooth multi-hop network deployments were reported. The turnaround was triggered by the release of the Bluetooth Low Energy Mesh Profile which is unquestionable a great achievement but not well suited for all use cases of multi-hop networks. This paper surveys the tremendous work done on Bluetooth multi-hop networks during the last 20 years. All aspects are discussed with demands for a real world Bluetooth multi-hop operation in mind. Relationships and side effects of different topics for a real world implementation are explained. This unique focus distinguishes this survey from existing ones. Furthermore, to the best of the authors’ knowledge this is the first survey consolidating the work on Bluetooth multi-hop networks for classic Bluetooth technology as well as for Bluetooth Low Energy. Another individual characteristic of this survey is a synopsis of real world Bluetooth multi-hop network deployment efforts. In fact, there are only four reports of a successful establishment of a Bluetooth multi-hop network with more than 30 nodes and only one of them was integrated in a real world application - namely a photovoltaic power plant. © 2019 The Author

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

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

Performance enhancements for single hop and multi-hop meshed high data rate wireless personal area networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.The High Data Rate (HDR) Wireless Personal Area Networks (WPANs) typically have a limited operating range and are intended to support demanding multi-media applications at high data rates. In order to extend the communication range, HDR WPANs can operate in a wireless mesh configuration (i.e. enable multiple WPAN clusters) to communicate in a multi-hop fashion. HDR WPANs face several research challenges and some of the open key issues are limited capacity, optimum resource allocation to requesting devices and maintaining Quality of Service (QoS) for real time multimedia flows. Although, there have been some scheduling algorithms proposed for HDR WPANs, the main objective is to maintain the QoS in most cases whereas efficient and fair utilization of network capacity is still largely open for research. This thesis mainly intends to resolve the issues related to capacity of HDR WPANs such as admission control, fair allocation of Channel Time Allocations (CTAs), improvement in capacity through transmission power control, and efficient utilization of time by each flow. A technique which re-orders the time slots to reduce queuing delay for meshed WPANs is also proposed and evaluated. The first contribution aims to improve peer-to-peer connectivity in case of two or more independent piconet devices by proposing an inter-PAN communication framework that is augmented by an admission control strategy to handle the cases when the superframe capacity is congested. The queued devices are prioritized by proposing a parameter called the Rejection Ratio. The second contribution consists of a resource allocation framework for meshed WPANs. The main objectives are to reduce the control traffic due to high volume of channel time reservation requests and introduce an element of fairness in the channel time allocated to requesting devices. The objectives are achieved by using traffic prediction techniques and an estimated backoff procedure to reduce control traffic, and define different policies based on offered traffic for fair allocation of channel time. The centralized scheme uses traffic prediction techniques to use the proposed concept of bulk reservations. Based on the bulk reservations and resource allocation policies, the overall overhead is reduced while an element of fairness is shown to be maintained for certain scenarios. In the third contribution, the concepts of Time Efficiency and CTA switching are introduced to improve communication efficiency and utilization of superframe capacity in meshed WPANs. Two metrics known as Switched Time Slot (STS) and Switched Time Slot with Re-ordering (STS-R) are proposed which aim to achieve the purpose. The final contribution proposes and evaluates a technique called CTA overlappnig to improve capacity in single hop and meshed WPANs using tramission power control. Extensive simulation studies are performed to analyze and to evaluate the proposed techniques. Simulation results demonstrate significant improvements in meshed WPANs performance in terms of capacity utilization, improvement in fairness index for CTA allocation by upto 62% in some cases, reduction in control traffic overhead by upto 70% and reduction in delay for real time flows by more than 10% in some cases

Distributed Topology Organization and Transmission Scheduling in Wireless Ad Hoc Networks

An ad hoc network is a set of nodes that spontaneously form a multi-hop all-wireless infrastructure without centralized administration. We study two fundamental issues arising in this setting: topology organization and transmission scheduling. In topology organization we consider a system where nodes need to coordinate their transmissions on a non-broadcast frequency hopping channel to discover each other. We devise a symmetric technique where two nodes use a randomized schedule to synchronize and connect in minimum time. This forms the basis for a topology construction protocol where a set of initially unsynchronized nodes are quickly grouped in multiple interconnected communication channels such that the resulting topology is connected subject to channel membership constraints imposed by the physical layer. In the transmission scheduling problem we consider Time Division Multiple Access (TDMA)the network operates with a schedule where at each slot transmissions can be scheduled without conflicts at the intended receivers. TDMA can provide deterministic allocations but typically relies on two restrictive assumptions: network-wide slot synchronization and global knowledge of network topology and traffic requirements. We first introduce an asynchronous TDMA communication model where slot reference for each link is provided locally by the clock of one of the node endpoints. We study the overhead introduced when nodes switch among multiple time references and propose algorithms for its minimization. We then introduce a distributed asynchronous TDMA protocol where nodes dynamically adjust the rates their adjacent links via local slot reassignments to reach a schedule that realizes a set of optimal link rates. We introduce fairness models for both links and multi-hop sessions sharing the network and devise convergent distributed algorithms for computing the optimal rates for each model. These rates are enforced by a distributed algorithm that decides the slots reassigned during each link rate adjustment. For tree topologies we introduce an algorithm that incrementally converges to the optimal schedule in finite time; for arbitrary topologies an efficient heuristic is proposed. Both topology organization and transmission scheduling protocols are implemented over Bluetooth, a technology enabling ad hoc networking applications. Through extensive simulations they demonstrate excellent performance in both static and dynamic scenarios

Providing Security to Wireless Packet Networks by using Optimized Security Method

Now-a-days technology is growing very fast, due to rapid development of the technology in computer arena, communication through network become a habit to the users. Communication through network is happen using two channels i.e., by connection oriented and connection less. At present users prefer wireless networks for communication and transferring data due to its flexibility. So in this paper we are focusing on wireless networking, as it is not reliable we are proposing an optimized security technique to provide security to the communication on wireless. In this paper we mainly focus on packet scheduling which plays the vital role in the transmission of data over wireless networks. We are using optimized security technique to secure the packets at initial level itself while scheduling the packets. Keywords: Real-Time Packets, Packet Scheduling, Wireless Networks, Security, Cryptography, Secret key, Bandwidth

Mobile Ad hoc Networking: Imperatives and Challenges

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 MANET\u27s characteristics, capabilities, applications, and design constraints. The paper concludes by presenting a set of challenges and problems requiring further research in the future

Wireless personal area networks and free-space optical links

This thesis is concerned with the link layer design of indoor (IrDA) and outdoor infrared links, as well as the performance of the higher layers of two major Wireless Personal Area Network (WPAN) technologies: IrDA and Bluetooth. Recent advancesin wireless technology have made it possible to put networking technology into small portable devices. During the past few years, WPAN technologies have been the subject of a tremendous growth both in research and development. Although many studies have been conducted on wireless links to address different issues on physical and link layers, wireless communications are still characterised by high error rates becauseof the frequently changing medium. On the other hand, performance studies of the higher layers are also very important. In this thesis, for the first time, a comprehensivestudy of the interactions betweenthe higher and the lower protocol layers of IrDA and Bluetooth has been carried out to improve the overall system performance. Mathematical models for the link layers are introduced for the infrared systems: infrared data association (IrDA) and free space optics (FSO). A model for the IrDA (indoor infrared) link layer is developed by considering the presence of bit errors. Based on this model, the effect of propagation delay on the link through put is investigated. An optimization study is also carried out to maximize the link throughput. FSO (outdoor infrared) links are often characterized by high speed and long link distance. A mathematical model for the FSO link layer is also developed. Significant improvement of the link throughput is achieved by optimizing the link parameters. Based on the link layer model, the performance of the IrDA higher layers (transport, session and application layers) is investigated. First, a mathematical model of TinyTP (transport protocol) is elaborated and subsequently verified by simulations. The effects of multiple connections and available buffer size are investigated. The throughput at the TinyTP level is optimized for different buffer sizes. Subsequently, the session layer, including Object Exchange (OBEX) and IrDA Burst (IrBurst) protocols, is studied and modelled. The derived mathematical model is verified by simulation results. A set of protocol parameters and hardware selection guidelines is proposed to optimize the overall system performance while also keeping the hardware requirementto a minimum. Finally, two rapidly developing IrDA applications, IrDA financial messaging(IrFM) and IrDA simple connection (IrSC), are studied. IrFM is investigated by comparison to other digital payment technologies, while the performance of IrSC is compared in two different technical approaches. In order to improve the throughput and minimize the transmission delay for the Bluetooth data applications, a systematic analysis is carried out for the Bluetooth Logical Link Control and Adaptation Layer Protocol (L2CAP). L2CAP is layered above the Bluetooth link layer (Baseband) and is essential to Bluetooth data applications. A simple and intuitive mathematical model is developed to derive simple equations for the L2CAP throughput and the average packet delay. The derived throughput equation, which is validated by simulations, takes into account bit errors as well as packet retry limits. Finally, a number of easy-to-implement performance enhancement schemes are proposed, including the optimum use of the protocol parameters