COMMUNICATION SYNCHRONIZATION IN CLUSTER-BASED WIRELESS SENSOR NETWORK: A REVIEW
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paper_title: Energy-Efficient Multihop Polling in Clusters of Two-Layered Heterogeneous Sensor Networks

paper_content:

In this paper, we study two-layered heterogeneous sensor networks where two types of nodes are deployed: the basic sensor nodes and the cluster head nodes. The basic sensor nodes are simple and have limited power supplies, whereas the cluster head nodes are much more powerful and have many more power supplies, which organize sensors around them into clusters. Such two-layered heterogeneous sensor networks have better scalability and lower overall cost than homogeneous sensor networks. We propose using polling to collect data from sensors to the cluster head since polling can prolong network life by avoiding collisions and reducing the idle listening time of sensors. We focus on finding energy-efficient and collision-free polling schedules in a multihop cluster. To reduce energy consumption in idle listening, a schedule is optimal if it uses the minimum time. We show that the problem of finding an optimal schedule is NP-hard and then give a fast online algorithm to solve it approximately. We also consider dividing a cluster into sectors and using multiple nonoverlapping frequency channels to further reduce the idle listening time of sensors. We conducted simulations on the NS-2 simulator and the results show that our polling scheme can reduce the active time of sensors by a significant amount while sustaining 100 percent throughput.
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Title: COMMUNICATION SYNCHRONIZATION IN CLUSTER-BASED WIRELESS SENSOR NETWORK: A REVIEW

Section 1: INTRODUCTION
Description 1: Introduce the concept of Wireless Sensor Networks (WSNs), their applications, and the importance of energy efficiency. Discuss the challenges of WSNs and the role of clustering in improving efficiency and scalability.

Section 2: RELATED WORK
Description 2: Review previous work on energy efficiency and scalability in WSNs, focusing on cluster formation algorithms in both homogeneous and heterogeneous environments.

Section 3: TYPES OF SCHEDULING
Description 3: Describe the two types of scheduling proposed in the paper: synchronous and asynchronous scheduling. Provide an overview of the assumptions and setup for these scheduling approaches.

Section 4: Synchronous Scheduling
Description 4: Explain the TDMA-based cycle-based scheduling (CBS) approach, its operation in intra-cluster and inter-cluster communications, and how it saves energy and minimizes synchronization overhead.

Section 5: Asynchronous Scheduling
Description 5: Introduce the New Clustering Scheduling (NCS) approach, which eliminates synchronization problems. Discuss the new clustering structure involving relay nodes and their role in inter-cluster communication.