Methods for Interference Management in Medical Wireless Sensor Networks

Emerging Medical Body Area Networks (MBANs) require new, protected spectrum for clinical applications. This may mean uncoordinated and autonomous operation of multiple MBANs, within the new candidate bands. The question is that how will MBANs coexist as a secondary service with other radio systems? Clinical environment requires balance of robust and efficient wireless techniques to enable coexistence of MBANs and other radio devices where low transmission power MBANs as secondary systems may be vulnerable to interference from incumbent devices transceivers. Physical separation between the MBANs and incumbent radio devices and avoiding the transmission in the same frequency bands among the wireless techniques may be considered. In this paper, we propose interferencemanagement techniques considering such coexistencebetween the MBANs and other radio systems and deal withthe issue of co-existence with primary systems by proposing novel methods for a gateway-to-gateway coordination, to assist the methods described in the first and second part of this paper. Result is improved reliability and Quality of Service for MBANs. These would lead to multiple clinical benefits, including better patient mobility, more monitoring flexibility and extension of monitoring into care areas that are currently unmonitored. Reduced clinical errors and reduced overall monitoring costs are other results

Analytic Conditions for Energy Neutrality in Uniformly-Formed Wireless Sensor Networks

Future deployments of wireless sensor network (WSN) infrastructures for environmental or event monitoring are expected to be equipped with energy harvesters (e.g. piezoelectric, thermal, photovoltaic) in order to substantially increase their autonomy. In this paper we derive conditions for energy neutrality, i.e. perpetual energy autonomy per sensor node, by balancing the node's expected energy consumption with its expected energy harvesting capability. Our analysis assumes a uniformly-formed WSN, i.e. a network comprising identical transmitter sensor nodes and identical receiver/relay sensor nodes with a balanced cluster-tree topology. The proposed framework is parametric to: (i) the duty cycle for the network activation; (ii) the number of nodes in the same tier of the cluster-tree topology; (iii) the consumption rate of the receiver node(s) that collect (and possibly relay) data along with their own; (iv) the marginal probability density function (PDF) characterizing the data transmission rate per node; (v) the expected amount of energy harvested by each node. Based on our analysis, we obtain the number of nodes leading to the minimumenergy harvestingrequirement for each tier of the WSN cluster-tree topology. We also derive closed-form expressions for the difference in the minimum energy harvesting requirements between four transmission rate PDFs in function of the WSN parameters. Our analytic results are validated via experiments using TelosB sensor nodes and an energy measurement testbed. Our framework is useful for feasibility studies on energy harvesting technologies in WSNs and for optimizing the operational settings of hierarchical WSN-based monitoring infrastructures prior to time-consuming testing and deployment within the application environment

TDMA-based MAC Protocols for Vehicular Ad Hoc Networks: A Survey, Qualitative Analysis and Open Research Issues

International audience—Vehicular Ad-hoc NETworks (VANETs) have attracted a lot of attention in the research community in recent years due to their promising applications. VANETs help improve traffic safety and efficiency. Each vehicle can exchange information to inform other vehicles about the current status of the traffic flow or a dangerous situation such as an accident. Road safety and traffic management applications require a reliable communication scheme with minimal transmission collisions, which thus increase the need for an efficient Medium Access Control (MAC) protocol. However, the design of the MAC in a vehicular network is a challenging task due to the high speed of the nodes, the frequent changes in topology, the lack of an infrastructure, and various QoS requirements. Recently several Time Division Multiple Access (TDMA)-based medium access control protocols have been proposed for VANETs in an attempt to ensure that all the vehicles have enough time to send safety messages without collisions and to reduce the end-to-end delay and the packet loss ratio. In this paper, we identify the reasons for using the collision-free medium access control paradigm in VANETs. We then present a novel topology-based classification and we provide an overview of TDMA-based MAC protocols that have been proposed for VANETs. We focus on the characteristics of these protocols, as well as on their benefits and limitations. Finally, we give a qualitative comparison, and we discuss some open issues that need to be tackled in future studies in order to improve the performance of TDMA-based MAC protocols for vehicle to vehicle (V2V) communications

Unified Role Assignment Framework For Wireless Sensor Networks

Wireless sensor networks are made possible by the continuing improvements in embedded sensor, VLSI, and wireless radio technologies. Currently, one of the important challenges in sensor networks is the design of a systematic network management framework that allows localized and collaborative resource control uniformly across all application services such as sensing, monitoring, tracking, data aggregation, and routing. The research in wireless sensor networks is currently oriented toward a cross-layer network abstraction that supports appropriate fine or course grained resource controls for energy efficiency. In that regard, we have designed a unified role-based service paradigm for wireless sensor networks. We pursue this by first developing a Role-based Hierarchical Self-Organization (RBSHO) protocol that organizes a connected dominating set (CDS) of nodes called dominators. This is done by hierarchically selecting nodes that possess cumulatively high energy, connectivity, and sensing capabilities in their local neighborhood. The RBHSO protocol then assigns specific tasks such as sensing, coordination, and routing to appropriate dominators that end up playing a certain role in the network. Roles, though abstract and implicit, expose role-specific resource controls by way of role assignment and scheduling. Based on this concept, we have designed a Unified Role-Assignment Framework (URAF) to model application services as roles played by local in-network sensor nodes with sensor capabilities used as rules for role identification. The URAF abstracts domain specific role attributes by three models: the role energy model, the role execution time model, and the role service utility model. The framework then generalizes resource management for services by providing abstractions for controlling the composition of a service in terms of roles, its assignment, reassignment, and scheduling. To the best of our knowledge, a generic role-based framework that provides a simple and unified network management solution for wireless sensor networks has not been proposed previously

On the Medium Access Control Protocols Suitable for Wireless Sensor Networks – A Survey

A MAC (Medium Access Control) protocol has direct impact on the energy efficiency and traffic characteristics of any Wireless Sensor Network (WSN). Due to the inherent differences in WSN’s requirements and application scenarios, different kinds of MAC protocols have so far been designed especially targeted to WSNs, though the primary mode of communications is wireless like any other wireless network. This is the subject topic of this survey work to analyze various aspects of the MAC protocols proposed for WSNs. To avoid collision and ensure reliability, before any data transmission between neighboring nodes in MAC layer, sensor nodes may need sampling channel and synchronizing. Based on these needs, we categorize the major MAC protocols into three classes, analyze each protocol’s relative advantages and disadvantages, and finally present a comparative summary which could give a snapshot of the state-of-the-art to guide other researchers find appropriate areas to work on. In spite of various existing survey works, we have tried to cover all necessary aspects with the latest advancements considering the major works in this area

Improving performance of body sensor networks in moderate-scale deployment scenarios

Ph.DDOCTOR OF PHILOSOPH

Interference-aware TDMA link scheduling and routing in wireless ad hoc networks.

Shen, Yuxiu.Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.Includes bibliographical references (leaves 61-64).Abstracts in Chinese and English.摘要........Error! Bookmark not definedAbstract --- p.iiiAcknowledgement --- p.vContent --- p.viiiList of Figures --- p.xiList of Tables --- p.xiiChapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Background Overview --- p.1Chapter 1.2 --- Motivation and Related Work --- p.2Chapter 1.3 --- Our Contribution --- p.3Chapter 1.4 --- Organization of the Thesis --- p.5Chapter Chapter 2 --- Preliminaries --- p.6Chapter 2.1 --- TDMA Technology --- p.6Chapter 2.1.1 --- Features of TDMA --- p.8Chapter 2.2 --- Previous Study on TDMA Link Scheduling --- p.8Chapter 2.3 --- Typical Network and Interference Models --- p.10Chapter Chapter 3 --- System Model --- p.14Chapter 3.1 --- Physical Layer Interference Model --- p.14Chapter 3.2 --- Objective of the Problem --- p.15Chapter 3.3 --- Rate Matrices for Transmission Sets --- p.17Chapter 3.4 --- Airtime Allocation --- p.19Chapter Chapter 4 --- Problem Formulation and Its Solution --- p.20Chapter 4.1 --- LP Formulation of Optimal TDMA Link Scheduling --- p.21Chapter 4.2 --- Solution to the Optimal Air Time Allocation Problem --- p.22Chapter 4.3 --- n-length Chain Network --- p.24Chapter 4.3.1 --- Adaptive Rate Transmission --- p.25Chapter 4.3.2 --- Fixed Rate Transmission --- p.27Chapter Chapter 5 --- Bad Transmission Set Removal Algorithm (BTSR) --- p.30Chapter 5.1 --- A 7-node Chain Example --- p.30Chapter 5.2 --- BTSR Algorithm --- p.32Chapter Chapter 6 --- Randomized Decentralized Scheduling Algorithm (RDSA) --- p.35Chapter 6.1 --- RDSA Algorithm --- p.35Chapter 6.2 --- Pseudo Code of RDSA --- p.37Chapter 6.3 --- The Flow Chart of RDSA --- p.39Chapter Chapter 7 --- Performance Evaluation --- p.41Chapter 7.1 --- Performance of Cross-layer TDMA Link Scheduling --- p.41Chapter 7.2 --- Complexity Analysis and Comparisons for BTSR+LP and LP --- p.46Chapter 7.2.1 --- Complexity of LP Problem --- p.47Chapter 7.2.2 --- Problem Size Reduced by BTSR --- p.48Chapter 7.2.3 --- Revised BTSR Algorithm --- p.49Chapter 7.2.4 --- The Complexity Issues --- p.51Chapter 7.3 --- Performance and Complexity Issues for RDSA --- p.52Chapter Chapter 8 --- Conclusion and Future Work --- p.57Chapter 8.1 --- Conclusions --- p.57Chapter 8.2 --- Future Work --- p.58Bibliograph