— Placing relays around the base station (BS) to assist wireless communication is an effective way of extending coverage in cellular systems. This paper provides a quantitative analysis of coverage extension by using decode-and-forward (DF) relays. To describe the relation between the number of relays and the coverage range extension, we introduce the concept of coverage angle and coverage range. We provide analytical upper and lower bounds for the coverage range in a cellular system for any given coverage angle. By means of simulations, we show the tightness of our analytical approach.