Delay Characteristics of Smart Grid Traffic in Wi-Fi Home Area Networks with and without Other Traffic

Smart grid is envisaged to be an IT enabled electricity generation and distribution system. National Institute of Science and Technology (NIST) has developed a conceptual model for the purpose of designing and developing a functional Smart Grid. This model has divided the entire Smart Grid operations into seven subdomains, so as to enable a segmented approach for the design. The Customer Domain plays an important role in Demand Response (DR) programs. To take part in DR programs, the Customer domain should be equipped with a Home Area Network (HAN). Communications within the Home Area Network should be accomplished with the acceptable time frames of DR requests while minimizing the energy footprint of the Home Area Network itself. Therefore, it is necessary to optimize the communications with respect to delay and energy constraints. The use of dedicated networks with specialized protocols is becoming common. However, having a separate network for HAN communications may create a significant energy footprint. Most houses nowadays have Wi-Fi networks used for other purposes. This paper focuses on using these existing Wi-Fi networks within homes for DR communications and study the effect of the available capacity on the mean delay of responses. This study was performed in a simulated environment with a central controller sending out requests to 25 nodes. The delay between sending out the request and reception of responses was recorded for 100 requests. The simulation was repeated varying the available capacity form 100 kb/s to 56 Mb/s in steps. The result shows that a capacity of 3 Mb/s can support the proper functioning of a DR system. However, when the same simulation was performed with normal traffic in the network, the result varies significantly. Still the network can support DR communications provided that there is a spare bandwidth of 10 Mb/s.