# Coverage Extension for the UK Smart Meter Implementation Programme Using Mesh Connectivity
## 1 Introduction  
With the help of intelligent sensors in smart cities, data can be sent wirelessly over long distances at a low cost with low energy consumption. Several high-data rate transfer protocols and technologies are now available, but none of them appear to be compatible with the communication standards used by intelligent sensors and control equipment. In addition to data speeds, this connection requires low tenancy and power consumption at narrower bandwidths. Authors in Ref. [1] presented a comprehensive survey on the challenges in smart cities, and one of the most pressing challenges is the network interconnectivity and subsequent transfer of data. This interconnectivity, especially for the Internet of Things, requires ubiquitous and veracious wireless coverage. Depending on the application, these requirements vary as some may require a low bandwidth, longer distances, and a lower frequency of data transfer. This paper focuses on the deployment of smart meters for collecting energy consumption data from households spread across a wide area. Since ZigBee technology meets all these requirements, it is \"a best match\" for several embedded applications, including consumer and industrial control systems in smart environments, such as smart cities. According to IEEE 802.15.4 standards for Wireless Personal Area Network (WPAN), Zigbee is mostly utilised for sensor and automation control networks. The kind of communication standard determines how many devices may contact the MAC layer at low data rates. Depending on the application, this technology can work at frequencies of 868 MHz, 902-928 MHz, and 2.4 GHz; nevertheless, a data rate of 250 kbps is ideal for two-way communication between several sensor nodes and controllers [2]. Smart metering is one of the most popular IoT applications and is a contender for Zigbee technology; however, good coverage for these devices over long distances requires extending coverage into hard-to-reach locations, such as deep indoors and basements. There do not appear to be many studies looking particularly at 868 MHz low-power transmission within house-to-house propagation scenarios. There was a study conducted by the University of Sheffield which considered the problem of extending the transmission range of a ZigBee radio, and their work noted that the antenna technology used has a strong influence on the transmission range of a smart meter terminal. However, their study did not take into account the practical deployment scenarios within the UK housing stock. Further work in Refs. [3, 4, 5, 6, 7, 8, 9, 10, 11] provides more related and background information for these measurements, and these references have been used as background material to extend our work. The authors of Ref. [12] carried out coverage evaluations of Zigbee technology in the 2.4 GHz band. With experiments carried out in a home environment, they showcased how linear interpolation theory can be used to evaluate the working of each node. They conducted theoretical analysis, which lacks the understanding of physical large-scale deployment. Similarly, for coverage evaluation and extension, Qin in Ref. [13] took advantage of a heterogeneous network consisting of WiFi and Bluetooth in addition to Zigbee operating at 2.4 GHz. With experiments, the authors showed how coverage can be expanded into hard-to-reach regions of a house; however, their evaluation was based on a small-scale network within a single-house environment. Similarly, the authors of Ref. [14] carried out simulations to evaluate the Zigbee performance for smart homes. There have been multiple studies investigating the coverage enhancement of LoRa networks [15, 16, 17, 18, 19] using mesh and/or multi-hop connectivity; however, these studies lack the evaluation of Zigbee networks at a large scale with physical deployment and at the 868 MHz band. To improve the coverage for the 868 MHz band, especially in the mesh scenario, it is imperative to understand the propagation loss at a large scale.