Date Added: Sep 2012
Wireless Sensor Network (WSN) is a network of spatially distributed, autonomous sensors nodes deployed for various kinds of monitoring applications. To enable reliable communications between sources to destination, many routing protocols have been proposed in the past by many researchers. These protocols are designed considering inherent sensor nodes constraints i.e. limited battery backup, memory and computation capacity. Generally, routing protocols in WSNs have been classified on the basis of their route determination techniques such as proactive, reactive and hybrid. Further routing protocols classification is done on the basis of query-based techniques. This paper briefly discusses the various routing algorithms and few concurrent open research issues are also summarized.