On Contention-Based 2-Step Random Access Procedure

In wireless communication, random access procedure is initialized before a user equipment(UE) starts a data transmission. The traditional random access procedure, which is called 4-step Random Access channel(RACH), includes two times of interaction between base station(BS) and UE. In this contribution, a simplified random access procedure named 2-step RACH has been introduced, which requires only one interaction between BS and UE, and thus can provide benefits in terms of signaling overhead, power consumption and latency. The basic concept of 2-step RACH, as well as the quantitative analysis compared with 4-step RACH are illustrated in details. In order to alleviate the inter-user interference caused by asynchronous non-orthogonal data transmissions, advanced receiver such as, multiwindow Minimum Mean Square Error Successive Interference cancellation(MMSE-SIC) is proposed to achieve better Packet Drop Rate(PDR) performance for multi-user detection.