Coverage and connectivity management in wireless sensor networks

Abstract

Both coverage and connectivity are the fundamental performance measures of the service provided by wireless sensor networks. Coverage represents how well the sensing goal of the network is accomplished, and connectivity represents how well the information can be delivered among the sensor nodes or to the central controller. Managing network coverage and connectivity is thus important in sensor networks. This thesis focuses on the coverage and connectivity management problem in wireless sensor networks. The coverage and connectivity management functions are classified into microscale management and macroscale management according to the geographical scale within which the sensor nodes collaborate.

This thesis first investigates several important coverage and connectivity management problems according to this categorization. In particular, for the microscale coverage and connectivity control problem, a Configurable Coverage Protocol (CCP) is proposed to control the ¿on¿ and ¿off¿ of the sensor nodes and meanwhile maintaining network coverage and connectivity. CCP is an efficient and lightweight protocol, in which each node makes decision based only on the collaboration between its local neighbors. Unlike existing protocols, CCP targets coverage of only alpha portion of the network, where alpha can be freely configured by the network administrators.

For the problem of microscale connectivity monitoring, a hashing based protocol (H2CM) is proposed for efficient neighbor table collection. Collecting neighbor tables from individual sensor nodes are generally hard due to the high communication cost. By utilizing connectivity-based constraints and several hashing techniques, H2CM allows the central controller to collect the neighbor tables from interested sensor nodes with very high probability, but with much lower communication cost.

Lastly, for macroscale topological hole detection and monitoring, a simple but powerful algorithm based on the connectivity changes of the sensor nodes is proposed. The algorithm first distributively elects the set of indicator nodes, and only the indicator nodes are required to send their information to the central controller. The location and size of the hole can be fairly accurately estimated using the information from only a few indicator nodes.

The thesis then integrates these individual management protocols and functions into a unified coverage and connectivity management system, which allows the network administrators to monitor and control the network coverage and connectivity, from both microscale and macroscale level. The dependencies of these individual components are analyzed and system initialization and operation sequences are explained.