Now a days, Wireless Sensor Networks (WSNs) are most growing research area because of its low cost, infrastructure less, increase capabilities of nodes, real time and accurate. Localization is a major issue in the wireless sensor networks because it has a number of sensor nodes which are deployed at positions and they may not be fixed at their own position. In localization different techniques are used for distance and position estimation. In this paper we will focus on RSSI based localization in WSN which will show how to reduce location errors and improve accuracy by using various models and techniques. After that we will focus on how to make an algorithm scalable and improve the energy efficiency by providing authentication and key management.

In this growing world, widespread and easily available use of mobile and portable devices such as, laptops, PDAs etc., the mobile ad hoc networks are receiving more attention for connectivity between these devices in real time. Ant Colony optimization routing is an adaptive and efficient for MANETs. Now a days, routing in mobile ad hoc networks (MANETs) is a very challenging and growing issue because of its dynamic nature and decentralization infrastructure. Various routing protocols have been proposed for MANETs but results in limited bandwidth, high throughput, end-toend delay, packet delivery ratio and more energy consumptions etc. An ant colony optimization algorithms have good techniques for developing different routing algorithms for MANETs. The reactive routing protocols like, AODV and DSR using Ant Colony optimization are review in this paper.