# Energy Efficient Multipath Routing Algorithm for Wireless Multimedia Sensor Network
## 1 Introduction  
Conventional wireless sensor networks (WSNs) consist of low-cost sensor nodes that are capable of sending scalar physical phenomena (e.g., temperature, pressure, and humidity), necessary computation, and transmitting data wirelessly [1]. New generation multimedia sensor nodes are capable of pervasively capturing multimedia contents as well as scalar data from the sensing fields. The availability of multimedia sensor nodes coupled with the novel distributed signal processing [2] and multimedia source coding algorithms [3] have enabled the emergence of wireless multimedia sensor networks (WMSNs) that are capable of capturing, transmitting and receiving multimedia contents [4]. WMSNs support many civilian and military applications such as the detection of plant diseases [5], the detection of the presence of insects [6], wildlife tracking [7], situation awareness [8], security monitoring [9], and automatic threat classification [10]. This inherent ability to be deployed for a wide range of applications has made WMSNs an attractive platform for applications that need pervasive access to multimedia contents. As a result, WMSNs-are increasingly gaining traction in the research community as well as in industry. In this paper, we address the problem of how to reduce energy consumption and routing overheads in WMSNs. One of the significant and essential requirements of WMSNs is the efficient transfer of multimedia data from a target node to the base station, taking into account several design considerationssuch as energy efficiency and fault tolerance. Minimizing energy consumption and overheads is an important issue in WMSNs because multimedia applications generally generate a high volume of network traffic. This traffic requires high transmission rates and processing capabilities from the nodes. Since both of these activities consume high energy, they will lead to premature node energy depletion and consequently shorten the WMSN network lifetime. Therefore, the design of an efficient and reliable routing protocol to maximize the network lifetime while simultaneously satisfying the quality of service requirements of the multimedia applications is critical in WMSNs. However, the inherent characteristics of WMSNs such as the variable channel capacity, limited bandwidth, and dynamic links pose severe challenges to routing protocol design for WMSNs. Furthermore, the limited resources of the sensor nodes such as energy, memory, buffer size, bandwidth, and processing capability all pose additional challenges to routing algorithm design for WMSNs. Moreover, the characteristics and requirements of multimedia applications, such as high bandwidth demand and bounded delay, further exacerbate the routing protocol design for WMSNs. Although many approaches have been proposed, the problem of a routing protocol design for WMSNs remains a challenge [11]. To address the aforementioned problem, developing a routing protocol that efficiently discovers and chooses a routing path between the sensing nodes and the sink, with low overheads, is very important in WMSNs. Routing protocols that employ a single path approach tend to be very sensitive to the highly dynamic nature of the wireless links and the limited capacity of the multi-hop path, which make them incapable of providing high data communication for WMSNs [12; 13; 14]. Moreover, the performance of the WMSN can be influenced profoundly by congestion [15; 16] since the sensor nodes have limited resources like bandwidth, memory, and computational energy. As a result, many different types of routing protocols with various approaches for enhancing the efficiency of the routing protocols such as clustering, multipath routing, and multi-hop routing have been advanced in the literature [17]. These routing protocols are almost always based on maximizing energy efficiency, and rarely consider efficient routing path selection and routing overhead issues simultaneously.