# Image Transmission over Cognitive Radio Networks for Smart Grid Applications
## 2 Related Works  
In smart grids, there is a diverse range of sensors and IEDs in value chains from consumers to DGs and vice versa. Although scalar sensors in the smart grids can provide valuable data, they also suffer from their limited information and restrictions [37; 38]. Thus, there are increasing needs for multimedia applications that require additional bandwidth for intranet communications within SGs [38; 39; 40]. In fact, there is the potential for massive multimedia applications for both end-users and commercial/industrial sectors in SGs [37; 38; 39; 40]. For example, wireless surveillance cameras can be installed in substations (NAN), home electric appliances and smart meters (HAN) to achieve high levels of safety and security [41]. Multimedia data that collected can be analyzed either to identify network faults and failures or to detect tampering of smart meters. Another example of multimedia applications in SGs was presented in [42]. They deployed multimedia sensors for solar panels that can predict the amount of energy produced [42]. In [5], a new idea based on computer vision and a wireless camera network was introduced to estimate wind turbine velocity. This information can be used for energy predictions in DGs. Having an accurate estimation of the production rate of DGs plays a significant role in load management and optimal power distribution within the power network [43]. These new services in SGs depend on ICT infrastructures. Among all smart grid experts, there is a general agreement on the need for two-way communication networks to establish the flow of information among the different components of the power network. However, there is still many debates about which of the specific communication technologies (both cable and wireless) should be applied in different network types in SGs [1; 15]. Indeed, this is a hard challenge among researchers in this field of work and there is no clear and applicable response to the issue until now [44; 45]. Given the fact that the effective information sharing throughout the network is a key factor to the success of smart grid technology, SG communication subsystems should meet quality of services mentioned in the SG standards [46]. Nowadays, we face huge growth of wireless technologies in the form of cellular networks, satellite networks, wireless sensor networks, IoT and etc [47; 48; 49; 50]. Wireless networks have different strengths and weaknesses compared to wired networks. Due to the wide advantages of wireless networks, many studies address the weaknesses and persist to decrease their negative effects as much as possible. However, there are major challenges in the design and development of delay-sensitive and high bit rate wireless communication networks over SGs. Some of these problems are as follows:  
1. Need to transfer high volumes of information, including scalar sensors, measurement tools, multimedia data and control signals [17; 51]. 2. Increasing radio interference in the limited wireless spectrum [40]
3. The low rate of data transmission on existing standards such as IEEE 802.15.4 and their low performance in delay-sensitive applications [52]. 4. Managing media communication with heterogeneous Quality of Experience (QoE) for a wide variety of both users and data [12; 13; 53]. 5. Renewable and clean power resources such as solar energy and wind turbines usually have a wide geographic distribution in places where there are not any communication infrastructure [13; 19]. Among all wireless solutions in SG applications, wireless sensor network (WSN) is one of the main options in future generation power networks. WSNs are very low cost, scalable with high standards [41; 54; 55; 56]. Indeed, flexible WSNs can be a feasible and economical solution for communication platforms in measurement, monitoring, inspection, and remote sensing tasks in SGs [45].