Large-scale Outdoor Cell-free mMIMO Channel Measurement in an Urban Scenario at 3.5 GHz

TL;DR

This paper presents the most extensive outdoor measurement campaign for cell-free massive MIMO channels in an urban setting at 3.5 GHz, providing valuable data for accurate channel modeling.

Contribution

It introduces the first large-scale outdoor CF-mMIMO channel measurements in an urban environment, with over 20,000 AP locations and 80 UEs, using innovative measurement techniques.

Findings

Analysis of power-delay profiles across different AP locations

Insights into propagation environment effects on channel characteristics

Development of measurement and data processing methodologies

Abstract

The design of cell-free massive MIMO (CF-mMIMO) systems requires accurate, measurement-based channel models. This paper provides the first results from the by far most extensive outdoor measurement campaign for CF-mMIMO channels in an urban environment. We measured impulse responses between over 20,000 potential access point (AP) locations and 80 user equipments (UEs) at 3.5 GHz with 350 MHz bandwidth (BW). Measurements use a "virtual array" approach at the AP and a hybrid switched/virtual approach at the UE. This paper describes the sounder design, measurement environment, data processing, and sample results, particularly the evolution of the power-delay profiles (PDPs) as a function of the AP locations, and its relation to the propagation environment.