Real-time performance evaluation of relative calibration on the OAI 5G testbed

Magounaki, Theoni; Kaltenberger, Florian; Knopp, Raymond
ASILOMAR 2019, Asilomar Conference on Signals, Systems, and Computers, 3-6 November 2019, Pacific Grove, CA, USA

In this paper we describe the OpenAirInterface (OAI) C-RAN testbed deployed at Eurecom and present the real-time implementation and performance evaluation of a channel calibration scheme. The distributed MIMO operation in dense Time Division Duplex (TDD) radio networks requires accurate time and frequency synchronization and calibration for precoding. We achieve this by using a common reference and over-the-air (OTA) synchronization between remote radio units (RRUs), which is a much cheaper alternative to distributed synchronization using PTPv2-like protocols and special clock regeneration circuitry. Furthermore we perform channel measurements between the RRUs without interrupting the real-time operation in order to perform distributed channel reciprocity calibration which is required to exploit uplink (UL) channel estimates to infer the precoder performed on the downlink (DL) channel.

Invited paper in a conference
Pacific Grove
Communication systems
Eurecom Ref:
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