Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Duty Cycle Based Routing. <s> Geographic routing is a useful and scalable point-to-point communication primitive for wireless sensor networks. However, previous work on geographic routing makes the unrealistic assumption that all the nodes in the network are awake during routing. This overlooks the common deployment scenario where sensor nodes are duty-cycled to save energy. In this paper we investigate several important aspects of geographic routing over duty-cycled nodes. First, we extend existing geographic routing algorithms to handle the highly dynamic networks resulting from duty-cycling. Second, we provide the first formal analysis of the performance of geographic routing on duty-cycled nodes. Third, we use this analysis to develop an efficient decentralized sleep scheduling algorithm for reducing the number of awake nodes while maintaining both network coverage and a (tunable) target routing latency. Finally, we evaluate via simulation the performance of our approach versus running existing geographic routing algorithms on sensors duty-cycled according to previous sleep scheduling algorithms. Our results show, perhaps surprisingly, that a network of duty-cycled nodes can have slightly better routing performance than a static network that uses comparable energy. Our results further show that, compared to previous algorithms, our sleep scheduling algorithm significantly improves routing latency and network lifetime. <s> BIB001 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Duty Cycle Based Routing. <s> This paper focuses on studying the impacts of a duty-cycle based CKN sleep scheduling algorithm for our previous designed TPGF geographical multipath routing algorithm in wireless sensor networks (WSNs). It reveals the fact that waking up more sensor nodes cannot always help to improve the exploration results of TPGF in a duty-cycle based WSN. Furthermore, this study provides the meaningful direction for improving the application-requirement based QoS of stream data transmission in duty-cycle based wireless multimedia sensor networks. <s> BIB002 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Duty Cycle Based Routing. <s> Advances in wireless sensor network (WSN) technology has provided the availability of small and low-cost sensor nodes with capability of sensing various types of physical and environmental conditions, data processing, and wireless communication. Variety of sensing capabilities results in profusion of application areas. However, the characteristics of wireless sensor networks require more effective methods for data forwarding and processing. In WSN, the sensor nodes have a limited transmission range, and their processing and storage capabilities as well as their energy resources are also limited. Routing protocols for wireless sensor networks are responsible for maintaining the routes in the network and have to ensure reliable multi-hop communication under these conditions. In this paper, we give a survey of routing protocols for Wireless Sensor Network and compare their strengths and limitations. <s> BIB003 </s> Survey of QoS routing protocols in Wireless Multimedia Sensor Networks <s> Duty Cycle Based Routing. <s> Wireless Sensor Networks (WSNs) have enjoyed dramatic developments over the last decade. The availability of CMOS cameras and microphones enlarged the scope of WSNs paving the way to the development of Wireless Multimedia Sensor Networks (WMSN). Among the envisaged WMSN applications, Real-time Multimedia Monitoring constitutes one of the most promising. However, the resource requirements of these applications place difficult challenges in terms of network lifetime and scalability. This paper starts by identifying the main characteristics and requirements of Real-time Multimedia Monitoring applications and then highlights key research directions that may help to overcome those challenges. <s> BIB004
A sensor node consumes maximum amount of energy when communicating (transmitting and receiving) with other nodes. To conserve energy, sensor nodes should be switched to sleep mode when there is no data to transmit/receive and woken up to active mode whenever required. This active and sleep mode of a sensor node together are referred to as duty cycling. Duty cycle based routing reduces energy consumption, resulting in an increase in network lifetime. It schedules the node radio state depending on network activity to minimize idle listening mode and to favor the sleep mode. Static duty cycle schemes based on fixed duty cycle save less energy and are not suitable for WMSNs. Thus, dynamic, adaptive duty cycle schemes are required which should be based on current traffic load, traffic priority, network topology, residual energy, and sensor density. However, the most challenging task is achieving dynamic duty cycling control due to the volatile nature of the video traffic. A duty cycle makes a huge impact on multipath routing. Work done to support static duty cycle based routing has been reported in WMSNs BIB001 BIB002 . Figure 6 shows two simulation scenarios of CKN BIB001 based TPGF BIB002 using NetTopo  simulator. A number of sleeping nodes (black color) are more in Figure 6 (a) compared to Figure 6 (b). Due to this reason a number of paths found from source (red color) to sink (green color) are less in Figure 6 (a) compared to Figure 6 (b). Adaptive duty cycle based routing is relatively unexplored and can be a further area of research BIB004 BIB003 .