A hybrid network architecture comprised of wireless sensor networks and cellular network is considered to monitor the high voltage transmission lines (HVTL). Corona noise is one of the sources of electromagnetic interference in HVTL. Automatic repeat request (ARQ) is utilized to increase the system reliability and to reduce the errors due to impulsive Corona noise. By using ARQ, link reliability is increased at the expense of communication delay. In this paper, the objective is to find the optimum location of ZigBee gateways such that reliability and latency constraints are satisfied. A cross-layer optimization technique is used to illustrate the effects of physical and MAC layer parameters on the QoS of the data collection.