Multimedia applications have become an essential part of our daily lives, and their use is flourishing day by day. The area of wireless sensor network is not an exception where the multimedia sensors are attracting the attention of the researchers increasingly, and it has shifted the focus from traditional scalar sensors to sensors equipped with multimedia devices. The multimedia sensors have the ability to capture video, image, audio, and scalar sensor data and deliver the multimedia content through sensors network. Due to the resource constraints nature of WSN introducing multimedia will add more challenges, so the protocols designed for multimedia wireless sensor network should be aware of the resource constraints nature of WSN and multimedia transmission requirement. This paper discusses the design challenges of routing protocols proposed for WMSN. A survey and comprehensive discussion are given for proposed protocols of WMSN followed by their limitations and features.

Multimedia applications are gradually becoming an essential—and flourishing—part of our daily lives. The area of wireless sensor networks is not an exception to this trend, as multimedia data have attracted the attention of researchers. Their importance is due to the shift of focus from traditional scalar sensors to sensors equipped with multimedia devices, as well as to the next-generation wireless multimedia sensor networks (WMSNs). The highly sensitive nature of multimedia traffic makes data routing with security even more important in WMSNs. This paper discusses the challenges of secure routing in WMSNs, where most of the proposed works in the literature deal with routing and security as individual issues. A critical and comprehensive review of state-of-the-art routing and security approaches for WMSNs is presented, followed by the discussion of their limitations and features. It is hoped that this extensive review and discussion ultimately identifies the future research directions and the open challenges of secure routing approaches in WMSNs.

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SUMMARYRecent literature characterizes future wireless sensor networks (WSN) with dynamic spectrum capabilities. When cognitive radio is introduced as a main component of a network, a network management protocol is needed to ensure network connectivity and stability especially in highly dynamic environments. Implementing such protocols in WSN opens more challenges because of the resource constraints in sensor networks. We propose a distributed lightweight solution that fulfills this need for WSN. With this protocol, a node in a multichannel environment is quickly able to establish a control channel with neighboring nodes. Lightweight distributed geographical either increases or reduces the coverage area of the control channel based on perceived interference and adequately takes care of intersecting nodes with minimal overhead. By identifying local minima nodes, it also has the potentiality of reducing route failure by 70% further reducing the time and energy overhead incurred by switching to angle routing or maximum power transmission schemes usually used to solve the local minima issue. The work shows best operating values in terms of duty cycle and signal to noise ratio threshold frequencies and the lightweight nature of lightweight distributed geographical in terms of energy and communication overhead, which suits network management protocols for cognitive radio sensor networks.