Time-based localization of a mobile station (MS) in a cellular network is usually performed by utilizing a pseudonoise transmission and a range difference-based positioning protocol. In this paper, we propose a novel positioning system using multicarrier transmission for orthogonal frequency division multiplexing-based cellular networks. For this system, a novel localization protocol is presented in which we propose four possible positioning methods to be analyzed and compared in conjunction with the novel protocol. Toward this goal, a unified Cramer-Rao lower bound (CRLB) is derived theoretically for all four methods. We also use best linear unbiased estimator (BLUE)-based algorithms to implement the proposed methods when locating a MS using cellular base stations. Their performance is discussed and compared in terms of the positioning error covariance matrix (PECM). Theoretical analysis is provided in the paper which demonstrates that BLUE-based location methods can approach the CRLB asymptotically under some conditions and that our positioning protocol has a better localization accuracy than either a range-based positioning protocol or a range difference-based one with respect to PECM. Finally, this paper verifies its theoretical findings by simulation.