Joint Activity Detection and Channel Estimation in Cell-Free Massive MIMO Networks with Massive Connectivity

12/24/2021
by   Mangqing Guo, et al.
0

Cell-free massive MIMO is one of the key technologies for future wireless communications, in which users are simultaneously and jointly served by all access points (APs). In this paper, we investigate the minimum mean square error (MMSE) estimation of effective channel coefficients in cell-free massive MIMO systems with massive connectivity. To facilitate the theoretical analysis, only single measurement vector (SMV) based MMSE estimation is considered in this paper, i.e., the MMSE estimation is performed based on the received pilot signals at each AP separately. Inspired by the decoupling principle of replica symmetric postulated MMSE estimation of sparse signal vectors with independent and identically distributed (i.i.d.) non-zero components, we develop the corresponding decoupling principle for the SMV based MMSE estimation of sparse signal vectors with independent and non-identically distributed (i.n.i.d.) non-zero components, which plays a key role in the theoretical analysis of SMV based MMSE estimation of the effective channel coefficients in cell-free massive MIMO systems with massive connectivity. Subsequently, based on the obtained decoupling principle of MMSE estimation, likelihood ratio test and the optimal fusion rule, we perform user activity detection based on the received pilot signals at only one AP, or cooperation among the entire set of APs for centralized or distributed detection. Via theoretical analysis, we show that the error probabilities of both centralized and distributed detection tend to zero when the number of APs tends to infinity while the asymptotic ratio between the number of users and pilots is kept constant. We also investigate the asymptotic behavior of oracle estimation in cell-free massive MIMO systems with massive connectivity via random matrix theory.

READ FULL TEXT
research
05/13/2021

Performance Analysis of Cell-Free Massive MIMO Systems with Massive Connectivity

In this paper, we investigate the performance of cell-free massive MIMO ...
research
05/21/2021

An Algorithm for Grant-Free Random Access in Cell-Free Massive MIMO

Massive access is one of the main use cases of beyond 5G (B5G) wireless ...
research
11/28/2021

Cell-Free Massive MIMO Detection: A Distributed Expectation Propagation Approach

Cell-free massive MIMO is one of the core technologies for future wirele...
research
09/28/2021

Two-Stage Channel Estimation Approach for Cell-Free IoT With Massive Random Access

We investigate the activity detection and channel estimation issues for ...
research
03/25/2019

Making Cell-Free Massive MIMO Competitive With MMSE Processing and Centralized Implementation

Cell-free Massive MIMO is considered as a promising technology for satis...
research
11/30/2020

Performance Analysis of Cell Free Massive MIMO systems in LoS/ NLoS Channels

In cellular communication systems, it is conventional to assume the abse...
research
01/16/2023

UL-DL duality for cell-free massive MIMO with per-AP power and information constraints

We derive a novel uplink-downlink duality principle for optimal joint pr...

Please sign up or login with your details

Forgot password? Click here to reset