Coverage and Connectivity in Wireless Sensor Network

Sensing coverage is an essential property of wireless sensor networks (WSNs). In addition to coverage, connectivity should also be considered to ensure correct operation in WSNs.Coverage measures the quality of surveillance offered by a WSN while connectivity enables the sensor to deliver the sensed data to the sink. Some of the applications of WSN such as intrusion detection and tracking require redundant coverage for accurate results. Most of the approach attempts to guarantee k-coverage in WSNs so that each point in the sensing area is covered by at-least k-active sensors.

Problem

The major problem in ensuring sensor coverage is associated with determining the appropriate number of sensors required for monitoring the target region. Similarly, the node density and mobility have great impact on connectivity. Sensors suffer from several resource constraints such as battery power, CPU, storage, and bandwidth.

Solution

Coverage Configuration Protocol (CCP)

A Coverage Configuration Protocol (CCP) is a protocol that can provide different degrees of coverage requested by applications. This flexibility allows the network to self configure for a wide range of applications and (possibly dynamic) environments. Coverage Configuration Protocol (CCP) can dynamically configure the network to provide different degrees of coverage as requested by applications. This flexibility allows the network to self-configure for a wide range of applications and environments with diverse or changing coverage requirements. The CCP protocol integrated both k-coverage and connectivity within a unified framework.

Drawbacks in CCP

 
  • The approach used in CCP requires a larger number of sensors to k-cover a field

  • The deployment increased number sensors, causes the energy wastage thereby reduces the lifetime of the sensor nodes

  • Additional energy is spent in sensing, and also to the communication overhead caused by the exchange of messages between active sensors running CCP to coordinate among themselves and provide the requested k-coverage service

  • CCP requires SPAN to provide connectivity between active sensors when R < 2r

Distributed Randomized Connected k-Coverage (DIRACCk)

 DIRACCk overcomes the drawback in CCP. The centralized protocol CERACCk does not rely heavily on global information. Thus, it can be redesigned in a fully distributed fashion based on the local information sensors have about their one-hop neighbors with regard to their physical locations and remaining energy called distributed randomized k-coverage (DIRACCk) which is a fully distributed k-coverage protocol. Also, DIRACCk design requires coordination among sensors to achieve k coverage of a field.

NS2 Solution

 
  • In ns2, a square field of area is considered where all the deployed sensors are randomly and uniformly distributed.

  • Energy model is applied, where the sensor energy consumption in transmission, reception, idle, and sleep modes are specified.

  • CCP protocol and DIRACCk protocol are simulated using a k – coverage algorithm varying the communication range and required degree of coverage.

  • Simulation results show that DIRACCk is more energy-efficient than CCP, with respect to the number of active sensors required for k-coverage and network operational lifetime.

Related Titles

 
  • Centralized and Clustered k-Coverage Protocols for Wireless Sensor Networks, IEEE TRANSACTIONS ON COMPUTERS, VOL. 61, NO. 1, JANUARY 2012

  • G. Xing, X. Wang, Y. Zhang, C. Lu, R. Pless, and C. Gill, “Integrated Coverage and Connectivity Configuration for Energy Conservation in Sensor Networks,” ACM Trans. Sensor Networks, vol. 1, pp. 36-72, 2005.