INTRODUCTION INTRODUCTION INTRODUCTION RELATED WORK

Sam Tran P. 3

I. INTRODUCTION

• A wireless sensor network WSN is a network of wireless sensor nodes. Each node is a computer with attached sensors that can process, exchange sensing data, as well as communicate wirelessly among themselves to perform various tasks. Figure 1: A typical sensor node structure and some of commercial sensor nodes Sam Tran P. 4

I. INTRODUCTION

• Wireless sensor networks have many efficiency applications in military and civil, which may be classified into three classes: data collection, surveillance, and object tracking Figure 2: An example of wireless sensor network for data collection in agriculture Figure 3: Indoor Navigator project at MIT Figure 4: A scenario enemy tracking using sensor network Sam Tran P. 5

I. INTRODUCTION

• Current challenges: – Small size of sensor node  Limit battery capacity and lower hardware performance. – The network is formed by randomly throwing thousands or even millions of sensor nodes in an area  Overlapping sensing areas redundancy. – The network is usually installed in a large area with many physical effects, such as earthquake, explosive, or etc.  The topology of the network has to be changed frequently. – Sensor nodes typically communicate via wireless links. Due to the limited bandwidth and interferences in the environment  Problems such as dropped packets and disconnected links. Sam Tran P. 6 • So, what we expect … A sensor network that • Employs multi-hop communication with. • Is reconfigurable. • Self-organizes including re-routing, redundancy reduction, and sensor deployment. • Thesis target Develop a method, called OCO Optimized Communication and Organization, which achieves the goals: • Redundancy reduction. • Efficient energy dissipation. • Low computation overhead on the sensor nodes. • Ensures maximum accuracy of object tracking Sam Tran P. 7

II. RELATED WORK

Direct Communication • The sensor module of all nodes is ON. • Nodes send data directly to the base. Advantages • Give the best accuracy. Disadvantages • Unrealistic because the base has limited number of channels. • Node energy is limited. • Cannot applied to a large area. • Suffer redundancy. According to a survey of Chuang National Tsing Hua Uni. in 52005, there are three main approaches for target tracking in sensor network: tree- based, cluster-based, and prediction-based. Of course, the Direct Communication is also a kind of approach. Figure 5: A scenario of direct communication Sam Tran P. 8

II. RELATED WORK