Spectral efficiency of multipair massive MIMO two-way relaying with imperfect CSI

Chuili Kong, Caijun Zhong, Michail Matthaiou, Emil Björnson, Zhaoyang Zhang

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)
302 Downloads (Pure)


We consider a two-way half-duplex relaying system where multiple pairs of single-antenna users exchange information assisted by a multiple-antenna relay. Taking into account the practical constraint of imperfect channel knowledge, we study the achievable sum spectral efficiency (SE) of the amplify-and-forward protocol, assuming that the relay employs maximum ratio processing. We derive a closed-form expression for the sum SE for arbitrary system parameters and a largescale approximation for the sum SE when the number of relay antennas, M, becomes sufficiently large. In addition, we study how the transmit power reduces with M to maintain a desired SE. Our results show that by using a large number of relay antennas, the transmit powers of the user, relay, and pilot symbol can be scaled down proportionally to 1/Mα , 1/Mβ , and 1/Mγ for certain combinations of α, β, and γ, respectively. This elegant power scaling law reveals a fundamental tradeoff between the transmit powers of the user/relay and pilot symbol. Finally, capitalizing on the new expressions for the sum SE, novel power allocation schemes are designed to further improve the sum SE.
Original languageEnglish
Number of pages14
JournalIEEE Transactions on Vehicular Technology
Early online date06 May 2019
Publication statusEarly online date - 06 May 2019


Dive into the research topics of 'Spectral efficiency of multipair massive MIMO two-way relaying with imperfect CSI'. Together they form a unique fingerprint.

Cite this