In this paper, we investigate the performance of a wide area network (WAN) with three hops over a mixed radio frequency (RF), reconfigurable intelligent surface (RIS) assisted RF and Free space optics (FSO) channel. Here RIS and decode-and-forward (DF) relays are used to improve the coverage and system performance. For general applicability, the RF and FSO links are modelled with Saleh-Valenzuela (S-V) and Gamma-Gamma distribution, respectively. In the smart grid (SG) communication network, the smart meter (SM) communicates the information from the devices to the data aggregator unit (DAU) through the RIS-assisted RF link. As all the devices are not switched on all the time, the Markov chain is used to model the number of active devices. The DAU retransmits the data to the meter data management system (MDMS) through the FSO link, where the atmospheric turbulence and pointing error impairments exist. In this context, closed-form expressions for average bit error rate (ABER) and outage probability (OP) are derived using the H-fox function and extended generalized Bi-variant H-fox function. Here the numerical results demonstrate the effect of different FSO parameters, the number of reflectors in RIS, traffic intensity, and the number of total devices in the SG network.
