Abstract
Recently, global positioning system (GPS)-enabled mobile units have been popular in wireless mobile communications systems, and thus it becomes possible for mobile units to estimate the velocity before a random access for initiating communications. Motivated by this, we propose a new random access scheme establishing two or more access slot groups corresponding to velocity ranges of mobile units, where each mobile unit attempts a random access only at the slot group corresponding to its current velocity. It gives advantages that access slots can be flexibly grouped according to vehicle traffic conditions and detection algorithms can be optimized to each velocity range.
