Title:	Grant Free Random Access in Cell Free Massive MIMO
DNr:	SNIC 2020/13-8
Project Type:	SNIC Small Compute
Principal Investigator:	Unnikrishnan Kunnath Ganesan <unnikrishnan.kunnath.ganesan@liu.se>
Affiliation:	Linköpings universitet
Duration:	2020-01-29 – 2021-02-01
Classification:	20203
Keywords:

Abstract

Massive access or massive connectivity is one of main use cases of beyond 5G (B5G) wireless networks. In this paper, we study the activity detection in grant free random access for massive machine type communications (mMTC) in cell free massive MIMO network. Each active device transmits a pre-assigned non orthogonal pilot sequence to the APs and the APs send the received signals to central processing unit (CPU) for joint activity detection. We propose a covariance based detection scheme which approximates maximum likelihood estimation based on the device to AP strongest link. Simulation results shows that the access probability of an active device with power constraints is significantly higher in distributed MIMO compared to co-located MIMO in mMTC scenario. We provide simulation results showing the performance of the algorithm in terms of probability of miss detection and probability of false alarm.