Transmission Control Protocol (TCP) can handle packet losses by retransmitting them when the corresponding acknowledgement (ACK) packets are not received within a certain time interval. This time interval is referred to as
(RTO) and setting its value is critical to reduce the packet delay in Smart Grid Advanced Metering Infrastructure (AMI) networks. In this paper, we propose a novel mechanism to set the RTO of each smart meter (SM) to improve the performance of TCP in IEEE 802.11s-based AMI networks in terms of packet delay. The idea is based on using the location of the SMs in the network topology and assign an RTO based on its distance from the gateway. In addition, we propose eliminating the doubling of RTO value when ACK packets are not received. The simulation results under ns-3 simulator indicate that the delay performance can be improved at least 40% with the use of these mechanisms.