This paper studies the possibility of performing radio localization by measuring the time-difference-of-arrival (UTDOA) using the uplink demodulation reference signal (DMRS) in 4G Long Term Evolution (LTE) cellular networks. The main problem of the Global Navigation Satellite System (GNSS) is the poor performance in indoor and urban canyon environments, which suffer from high signal attenuation and severe multipath propagation. With the increase of services based on the accurate location of the user, new techniques that cooperate with GNSS are necessary. The current release of the 3rd Generation Partnership Project (3GPP) LTE specification supports a UTDOA localization technique based on the Sounding Reference Signal (SRS). A Local Measurement Unit (LMU) uses knowledge of the SRS to perform the time difference measure. In this paper, an UTDOA technique that uses the DM-RS is proposed. We point out the advantages of our proposal and evaluate its feasibility by means of simulations.
