## 1 Introduction
### Motivation
Bit errors can be reduced to a certain level by information retransmissions and by using forward error correction methods [15]. The trade-off is excessive resource consumption such as energy and channel capacity. As energies of the sensor nodes are also limited, retransmission must be limited. It is specified in [15] that retransmission of a whole information frame/packet to correct a few error bits in an information frame/packet is a waste which confirms the preceding argument. Furthermore, restrictions have been made to maximum number of retransmission attempts in wireless standards [16; 17]. These retransmissions are acknowledgment-based retransmissions. In harsh environmental conditions in SGs, these retransmission frames/packets and acknowledgment frames/packets themselves can be lost. Additionally, low latency communication requirement for mission critical applications, heterogeneous network structure and traffic, and resource (energy, memory and processing) constraints are challenges that exist for wireless sensor networks in SGs [3; 13; 18]. Latency is the network delay, which is expressed as a time for a data frame/packet to successfully travel from one point to another. Intelligent cognitive radio-based SG can greatly reduce the latency and are aware of heterogeneous networks achieving the required quality of service for SGs [13; 19]. The latency requirement specifies that maximum tolerable latency should be 10 ms when the power grid is not broken down into asynchronous sections (non-islanding) and 100 ms for islanded (asynchronous) smart grid systems [20]. Preceding latency requirement was specified for the whole smart grid considering all the applications. However, the latency requirement can vary vastly based on the specific smart grid application [1]. The general recommendation is to use wired media such as fiber optic cables or transmit wireless using Wi-MAX to maintain latency less than 10 ms in Smart Grids covering a bigger area such as WANs. The performance analysis considered in this context particularly aims to address SGs consisting of FANs and HANs in which there is no requirement for mission critical applications having very low latency requirements, but having applications which have a maximum tolerable latency of 300 ms. Zig-Bee or Bluetooth can be used in HANs and Wideband Code Division Multiple Access (WCDMA) in FANs for Smart Grid WSNs [1]. As the transmission distance is relatively low (<10 km per link) in HANs and FANs, they can satisfy the low latency requirement of 300 ms for considered applications in this context in SG communication even under low data rates (10s to 100s of kbps). When considering the application layer in traditional power grids, power disturbances and outages occur due to equipment failures, capacity limitations, and natural accidents. These problems can be largely avoided through real time power grid condition monitoring and controlling. In generation side, renewable energy farms located in remote geographical areas must be frequently monitored. Critical parameters of solar farms such as radiation and temperature values, DC voltage and weather conditions are required to be collected in a timely manner. In distribution and transmission side, power quality, overhead, and underground cable conditions, conductor temperature and dynamic thermal rating must be collected. Gathered information will pave the way to take early precautionary measures. Therefore, an accurate, less complex and energy efficient data fusion technique is required which causes less network delay. We prove that the proposed statistical data fusion technique is such a fusion method that targets Specific SG applications such as Home Energy Management (HMI), Advanced Metering Infrastructure (AMI), outage management, demand response management, asset management, distributed energy resource and storage, vehicle to grid energy transferring, electric vehicle charging, etc., in which latency requirement is higher than 300 ms [3]. The security aspect of these SG applications are not considered in this context.