ABSTRACT
ABSTRACT Monitoring human movements using wireless sensory devices promises to revolutionize the delivery of health care services. Such platforms use inertial information of their subjects for motion analysis. Potentially, each action or disease can be discovered by collaborative processing of sensor data from multiple locations on the body. This functionality is provided by a body area network (BAN), which consists of several wireless sensor nodes positioned on different parts of the body. In spite of the revolutionary potential of this platform, power requirements and wearability have limited the commercialization of these systems. This chapter presents energy-efficient communication models for BAN applications using buffers to limit communication to higher-rate short bursts, decreasing power usage and simplifying the communication. Transmission at higher rates and in short bursts will create opportunities to reduce the energy per bit for communication,
CONTENTS
Introduction ................................................................................................................................. 204 Preliminaries ................................................................................................................................ 205
Communication Power Efficiency in BANs ....................................................................... 205 System Architecture and Signal Processing ....................................................................... 206 Collaborative Model .............................................................................................................. 206
Problem Definition ...................................................................................................................... 208 Buffer Assignment .................................................................................................................. 208 Problem Formulation ............................................................................................................. 210 Problem Complexity .............................................................................................................. 211
Greedy Algorithm ....................................................................................................................... 212 Static Buffer Allocation .......................................................................................................... 214 Dynamic Buffer Allocations .................................................................................................. 215
Link Deletion ...................................................................................................................... 217 Link Insertion ..................................................................................................................... 218
Performance of Buffer Allocation Algorithms ........................................................................ 218 Setup ......................................................................................................................................... 218 Experiment 1 ........................................................................................................................... 218 Experiment 2 ........................................................................................................................... 220
Concluding Remarks ..................................................................................................................222 References .....................................................................................................................................222
hence decreasing the overall energy consumption. This energy minimization is achieved via proper buffer allocation in this chapter. The buffer allocation problem is formulated as an optimization problem that reduces transmissions among sensor nodes. Both an integer linear programming (ILP) solution and a fast greedy heuristic algorithm are discussed to solve this power optimization problem. It is shown that despite the decreased transmission efficiency, the greedy algorithm can be adopted for fast allocation of buffers in real time. Performance of both the near-optimal and greedy solutions is compared against an unbuffered system using experimental analysis. It is demonstrated that ILP and greedy solutions can reduce the amount of transmissions by an average factor of 70% and 41%, respectively.
