A Review on Time Synchronization Free Localization Schemes in Underwater Wireless Sensor Networks

摘要

Underwater Wireless Sensor Networks (UWSN) has provided a flux to realm of location dependent underwater applications like oceanographic exploration, disaster prevention, tactical surveillance, mine reconnaissance, etc. Sensing of data is essential for all the applications and sensed data is meaningful only when the location information of sensor node is available. The procedure of estimating the location co-ordinates of the sensor node is known as localization. Location information is required for designing network architecture, data tagging, location-based routing protocols and node tracking. Thus, localization is essential in UWSN but it is difficult to achieve due to unavailability of GPS in underwater environment. Time synchronization and localization depends on each other but achieving time synchronization between sensor nodes is a tough task due to complex underwater characteristics like node mobility, limited bandwidth, multipath and fading effects, limited battery power, etc. This paper focuses on surveying the existing localization schemes in UWSN that do not use the concept of time synchronization. This paper also provides a comprehensive overview through comparison to analyze and summarize the localization schemes under concern.