# Energy Efficient Multipath Routing Algorithm for Wireless Multimedia Sensor Network
## 2 Related Work  
Routing algorithms for WMSNs is an active research area [15; 17; 19; 20]. A pair-wise directional geographical routing was proposed to solve energy issue in multi-path routing for WMSNs [21]. The scheme improves the network lifetime by compromising on the delay time. A seamless streaming data delivery protocol was proposed in [22]. The scheme applies cross-cluster handover and path redirection strategies to minimize delivery latency and energy consumption. However, the performance deteriorates with an increase in the size of the sensor network, e.g., the addition of powerful multimedia sensor nodes. Multipath routing has been an attractive approach in MWSN for reducing latency and energy consumption as well as attaining high throughput. A multipath routing algorithm called direct diffusion (DD), which has a query driven basis, is discussed in [23]. The algorithm begins its process by broadcasting a packet. The node which acquires the packet establishes a connection with the sender node. Likewise, multiple paths will be created between every pair of source and sink nodes. If a node identifies the presence of an event, it automatically delivers the information to the sink. The best path among the multiple paths will be chosen by the sink node using packet reception performance metrics such as minimum latency in the case of data communication. Nevertheless, this routing mechanism is more suitable for applications which are query-driven and contains all the drawbacks of DD. The REAR protocol [24] addresses energy efficiency and reliability in terms of data delivery. The protocol maintains an alternative path to the sink node and thus supports multi-path reliable data transmission. The base station (BS) starts the routing process by broadcasting a service-path query to the other nodes in the network. After receiving the message, the nodes will send back a reservation message to the BS to make sure that a path is discovered. The performance of the protocol has been evaluated in comparison with other existing techniques. However, distance related parameters are not considered in the REAR protocol. A multipath routing algorithm with a minimum delay for WSN is discussed in [25]. Parameters such as the network lifetime during braided and disjoint multipath techniques were used as one of the performance indicators when the protocol was compared with single path routing techniques. The criteria for choosing the best path is a minimum hop count. The algorithm achieves the minimum delay as compared to other existing algorithms. However, the algorithm does not consider residual energy and the distance. An algorithm called EECA is discussed in [26]. EFCA discovers two different collision-free paths. Furthermore, EFCA adopts constrained and power adjusted flooding by the base station to reduce unwanted energy wastage of the system. Though the simulation results verified its efficiency in terms of energy saving and data transmission, there is still an opportunity to improve EFCA since collisions along multiple paths often occur. A protocol for a real-time application that is reliable and delay aware is discussed in [27]. Reliability is achieved via using forward error correction (FEC). The delay constraint is satisfied by the redundant data introduced during the data communication. Similar to other protocols, it uses a flooding technique for multiple path discoveries. The remaining energy of the sensor node, distance to the sink node, and path length were not analyzed in the study and can be considered as a limitation of this work. In [28], the authors discussed the advantage of employing a multipath routing technique to achieve reliable data delivery in a wireless sensor network based on hop count and ring level. The ring level is used to divide the nodes into several sections. During network setup, the base station floods the network with messages to investigate and confirms which nodes are members of a certain ring level. The ring level will increase whenever the hop count increases.