International Journal of Computer Applications (0975 – 8887) Volume 74– No.12, July 2013 5 Network Structure and Topology based Routing Techniques in Wireless Sensor Network- A survey Rajendra Singh Bisht M.Tech Final Year Computer Science & Engineering BTKIT Dwarahat, Uttarakhand, India Shailendra Mishra,Ph.D Head of Department Computer Science & Engineering BTKIT Dwarahat, Uttarakhand, India ABSTRACT Routing techniques in Wireless Sensor Network has always been important area of exploration due to change in demands of various applications such as Area monitoring, Environmental/Earth monitoring, passive localization and tracking, Industrial monitoring etc. Energy efficiency is crucial issue in WSN because sensor nodes in WSN are with limited battery power/Resources .This results in rapid change in design of routing algorithms. Day by day various routing techniques are being proposed. It is because of energy efficiency, Scalability, Network lifetime and other important factors of routing techniques. Each routing mechanism has its advantages and disadvantages related to energy efficiency also. There is no single, best routing protocol that is suitable for all applications. Routing mechanism might differ depending on the application, network architecture and topologies. This paper gives review of recent research of the network structure and topology based different routing strategies and gives brief idea about energy efficiency of routing protocols in WSN. This paper also represents classification of various routing techniques with their advantages and disadvantages. Keywords Base station (sink), Clustering, Energy efficiency, Routing Protocols, Wireless Sensor Network 1. INTRODUCTION A Wireless Sensor Network (WSN) consists of various tiny nodes (called sensors) densely deployed in a small or large geographical area to monitor physical or environmental conditions, such as sound, temperature, Air direction, pressure, etc. wireless sensor networks are broadly used in civil, military ,security applications. A sensor has some capabilities which include collection/gathering of data from physical geographical area using embedded micro processor, aggregation of data, receiving of data, sending of data using radio transmitter to another similar node or to a sink (also called base station). This all work carried out by a node require energy to consume but nodes in WSN have limited battery power. Therefore, energy efficiency has always been a crucial factor and a challenge in the design of routing algorithms. Along with this, nodes in WSN have limited memory, limited computational capabilities. These nodes also can be considered as a collection of low-cost, low-power, and multifunctional wireless sensor nodes. WSNs are different from traditional wireless communication system (such as cellular systems and mobile ad hoc networks). Design issues for both systems are also different in nature. While designing routing protocols for WSNs the energy efficiency factor, fault tolerance, scalability of these protocols should be considered. To replace these challenges with proper solution many routing techniques have already been proposed in area of WSN. This paper describes existing routing techniques based on network structure and topologies in WSN and also present recent research of routing techniques for wireless sensor networks, including their advantages and disadvantages. 2. ROUTING TECHNIQUE AND ITS DESIGN CONSIDERATION IN WSN Routing is a technique of determining path from source to destination upon request of data transmission. Routing table is used to maintain address of nearest node. There may be one or more intermediate node/s between source and destination. A routing algorithm performs routing and maintenance of routing table. While designing the routing algorithms following consideration must be taken into account [1] 1. Sensor nodes in WSN may be stationary or mobile. 2. Single-hop routing technique consumes more energy than multi-hop but multi-hop results in overhead for topology management and medium access control. 3. Data delivery model (Reliability) to the sink can be continuous, event driven, query-driven and hybrid, depending on the application of the sensor network. 4. Data can be aggregated to remove redundancy. 5. Sensor node deployment is either deterministic or self- organizing. 6. A sensor node in WSN is multifunctional. It collects data, aggregates data, transmits data, and routes the data. 7. Power failure, physical damage or environmental interferences are cause of sensor node failure. The objectives of routing technique should be correct delivery of data (Real or non-real time) and maximization of network life time. 3. CLASSIFICATION OF ROUTING TECHNIQUES Many routing techniques have already been proposed in the area of wireless sensor network. Routing algorithms/Techniques have been classified in a number of ways by various researchers. There is no general classification is available till today. Some researchers [5, 22, and 23] have classified routing algorithms into three broad categories Data-centric Routing Protocols, Hierarchical Routing Protocols and Location-based Routing Protocols. Here a more general classification of routing techniques is presented. Most of the routing techniques fall into one of the following category. Routing techniques can be classified based on following:  On the basis of Route Selection or path establishment [4, 5, 6, 7,24] 1. Proactive protocols 2. Reactive protocols 3. Hybrid protocols  On the basis of protocol Operation [4, 6,24] 1. Negotiation based routing 2. Multipath routing protocols