# Robust Evolutionary-Game-Based Routing for Wireless Multimedia Sensor Networks
## 1 Introduction  
A wireless multimedia sensor network (WMSN) consists of wirelessly interconnected devices capable of retrieving multimedia contents, such as videos, audios, still images, and scalar sensor data from the environment [1; 2; 3]. The improvement and miniaturization of hardware can facilitate the development of sensor devices equipped with audio-visual multimedia modules [4]. Recently, the availability of cheap hardware, such as cameras and microphones, has had a great impact on the development of WMSNs. According to [5], a WMSN is a network of wirelessly interconnected sensor nodes that have multimedia devices and can retrieve video and audio streams along with the scalar sensor data. WMSNs can facilitate a wide range of applications in both public and military sectors. Surveillance sensor networks, law-enforcement reports, traffic control systems, advanced health care delivery, automated assistance to elderly telemedicine, and industrial process control are examples of such applications. In these applications, multimedia sensor nodes increase the amount of collected information, enlarge the range of coverage, and enable multi-resolution views [5]. Furthermore, multimedia sensor nodes collect snapshots and streaming multimedia contents. Snapshots are captured because of any event-triggered observation over a short period of time [4]. In contrast, streaming multimedia contents are captured and generated because of any event-triggered observation over a longer period of time. It is essential for WMSNs to have a strong foundation of hardware to satisfy the quality-of-service (QoS) requirements and fulfill application-specific demands. WMSNs require higher bandwidth as compared to traditional wireless sensor networks (WSNs). For example, Crossbow [6], which is an IEEE 802.15.4 compliant WSN platform, has a data transmission rate of 250 kB/s, which is very low for high-end multimedia sensors. WMSNs are required to beenergy-efficient to support high data rate; thus, more careful considerations should be given to conserve energy. Multimedia sensors produce large amount of data that require extensive processing, which consumes more energy and affects the network lifetime. Moreover, multimedia sensor nodes have a different concept of sensing region as compared to traditional WSNs. They have field of views (FoVs) and can capture images within a particular region. These operations are different from the sensing operations in traditional WSNs. The term FoV refers to the directional view of a multimedia sensor. The target object covered by a camera can be at a distant position. The images captured by the camera depend on the relative position and orientation of the camera toward the targeted object [7; 8; 9]. Over the last few years, many routing protocols have been proposed for WMSNs, which focus on energy efficiency, delay, and reliability. The real-time power aware routing (RPAR) protocol [10] dynamically adjusts transmission power and routing decision according to the network load and data packet size. Its unique forwarding and neighbor management mechanisms effectively save energy while meeting real-time constraints. However, RPAR fails to consider the energy hole and congestion problems. The routing protocol discussed in [11] adopts a cross-layer design approach between the network and MAC layers to distinguish between communication flows with different delay and reliability demands. However, it cannot control redundant data, which decreases energy efficiency and increases communication congestion. The distributed aggregate routing algorithm [12] determines multiple paths for multiple sinks while ensuring reliability. The operator calculus-based routing protocol [13] uses operator calculus methods on graphs to overcome the multi-QoS constrained routing problem. In this protocol, a node chooses the set of eligible next hops based on the given constraints and the distance to the sink. However, it ignores the impact of estimation accuracy on delay and reliability.