Near-far problem impact on mobile radiolocation accuracy in CDMA wireless cellular networks

This paper studies the performance of mobile radiolocation in CDMA wireless cellular networks using time-of arrival (TOA) based techniques. It is shown that the near-far problem due to other-cell multiple-access interference (which cannot be mitigated by power control mechanisms) adversely affects the ability of the other "non-serving" base stations to correctly estimate the TOA of the intended mobile signal. This in turn leads to poor positioning capability, which requires correct timing estimation by the serving base station and at least two additional ones. Different scenarios are examined based on the level of soft handover (SHO) connectivity of the mobile. Comparative numerical results are presented in order to illustrate the tradeoffs involved, and it is shown that positioning accuracy is improved when the mobile terminal is in 2-way or 3-way SHO.