Localization means finding or estimating the accurate position of nodes. Through localization, node sends the accurate location position with the information to the interested users. Localization algorithm is applied to every sensor nodes with respect to their coordinates. The earlier two dimensional localization algorithm works on flat network topology, it hard for 2D network to work with irregular network topology. The 2D may failed many time for finding position in complex hilly and harsh terrain and large altitude differences, for this we need for three dimension localization of nodes. The algorithm proposed in this paper for 3D localization i. e. Ring-Overlapping based on Comparison of Received Signal Strength Indicator (ROCRSSI) it is already implemented in 2D localization, this paper proposed this algorithm in 3D localization of node in sensor networks. Here we use finger-print approach to implement this algorithm. Finger-print techniques divide into two phase's online and off-line method. It takes the signature of node location in offline phase and store it on database and online phase new measurement is taken for finding the node position with respect to data. ROCRSSI is based on range-free method; its property is to work with the small number of anchor in the network, it is isotropy in nature so it provides equal radiation power to the distance node so that it can be used for long region area.

1. Jing WANG1, R. K. GHOSH2, Sajal K. DAS," A survey on sensor localization". J Control Theory 8 (1) 2–11 April 2010.
2. Samira Afzal, "A Review of Localization Techniques for Wireless Sensor Networks". Text Road Publication ISSN 2090-4304 Journal of Basic and Applied Scientific Research www. textroad. com, 2012-09-27.
3. Azzedine Boukerche and Horacio A. B. F. Oliveira, "Localization Systems for Wireless Sensor Networks". IEEE Wireless Communications, December 2007.
4. Li WANG, Jing ZHANG, Dun CAO. "A New 3-dimensional DV-Hop Localization Algorithm". Journal of Computational Information Systems 8: 6 (2012) 2463-2475, March 2012.
5. Hongyang Chen, Pei Huang, Marcelo Martins, Hing Cheung So, and Kaoru Sezaki "Novel Centroid Localization Algorithm for Three-Dimensional Wireless Sensor Networks". IEEE 978-1-4244-2108-4/08.
6. GUERRERO E, WANG Hao, ALVAREZ J, RIVERO L,"A Three-Dimensional Range-Free Localization Algorithm Based on Mobile Beacons for Wireless Sensor Networks". Vol. 20 No. 1 June 2010.
7. Jianping Xing, Dehua Wang, Yang Liu, "Distributed Range-Free Localization Algorithm for 3D Wireless Sensor Networks under Irregular Radio Propagation Model". Applied Informatics and Communication, Communications in Computer and Information Science Volume 224, 2011, pp 299-306, August 20-21, 2011.
8. Jorge J. Robles, Martin Deicke and Ralf Lehnert, "3D fingerprint-based localization for wireless sensor networks". 2010 7th Workshop on Positioning Navigation and Communication (WPNC), 978-1-4244-7158-4 IEEE 2010.
9. Chong Liu,Tereus Scott, Kui Wu, and Dan Hoffman, "Range-Free Sensor Localization with Ring Overlapping Based on Comparison of Received Signal Strength Indicator". International Journal of Sensor Networks, Volume 2 Issue 5/6 Pages 399-413, July 2007.
10. Chong Liu, Kui Wu,"Performance Evaluation of Range-Free Localization Methods for Wireless Sensor Networks". Computer science department, University of Victoria.
11. Chong Liu, Kui Wu, Tian He, "Sensor Localization with Ring Overlapping Based on Comparison of Received Signal Strength Indicator ". 2004 IEEE International Conference on Mobile Ad-hoc and Sensor Systems, 0-7803-8815, 2004 IEEE.
12. Tereus D. Scott,"Experimental Study of a Range-Free Localization Method for Wireless SensorNetworks". University of Victoria, 2006.
13. Andrija S. Velimirovi´c, Goran Lj. Djordjevi´c, Maja M. Velimirovi´c, and Milica D. Jovanovi´c. "A Fuzzy Set-Based Approach to Range-Free Localization in Wireless Sensor Networks". Facta Universitatis (Ni?S )Ser. : Elec. Energ. Vol. 23, No. 2, August 2010, 227-244.
14. Chong Liu, Kui Wu Computer Science Dept. "Performance Evaluation of Range-Free Localization Methods for Wireless Sensor Networks". Performance, Computing, and Communications Conference, 2005. IPCCC 2005. 24th IEEE International.
15. Tereus D. Scott. "Experimental Study of a Range-Free Localization Method for Wireless Sensor Networks". 2006.

Anchor nodes fingerprint techniques ROCRSSI algorithm and unknown node.