In this paper, we consider the problem of relay placement and resource sharing among the relays and the base station in a cellular network. Specifically, we focus on the problem of deploying half duplex relays in cellular systems employing soft frequency reuse (SFR) and fractional frequency reuse (FFR) schemes. For both SFR and FFR schemes, we propose strategies for relay placement and assigning mobile stations among the relays and the base station. We also propose strategies for allocating the spectrum among the relays and the base station, which are consistent with the frequency planning of SFR and FFR layouts. We study the performance of the proposed techniques using simulations of a cellular network with 19 cells layout. Our results show that the proposed relay-aided schemes achieve significant improvements in terms of both coverage probability and throughput over the conventional cellular system without relays. © 2015 IEEE.