Optimized in-band full-duplex MIMO relay under single-stream transmission

Umut Ugurlu, Taneli Riihonen, Risto Wichman

Research output: Contribution to journalArticleScientificpeer-review

29 Citations (Scopus)


This paper presents a coherent scheme to optimize an in-band full-duplex multiple-input-multiple-output (MIMO) relay via beamforming and transmit power allocation in a two-hop single-input-single-output (SISO) link under full channel knowledge and perfect hardware assumptions. First, we derive in closed form the optimal pair of transmit power and receive filter for a fixed transmit filter by unifying the minimum-mean-square-error (MMSE) filtering with the SISO-equivalent power allocation, as an iterative approach is not guaranteed to converge to global optimum. Second, we propose a heuristic algorithm to approximate the optimal transmit filter for a fixed receive filter. Furthermore, we study the well-known null-space projection constraint and derive a singular value decomposition (SVD)-based solution for the arbitrary-rank self-interference channel by generalizing the optimal solution under the assumption of rank-1 self-interference channel. Finally, we combine these solutions into a partially iterative algorithm in order to address the global optimization as our observations justify that some of the aforementioned schemes converge to the optimal solution under certain criteria. The numerical analysis of the proposed iterative algorithm demonstrates close-to-optimal performance relative to the theoretical upper bound of the end-to-end link in terms of maximum achievable throughput.

Original languageEnglish
Article number7021973
Pages (from-to)155-168
Number of pages14
JournalIEEE Transactions on Vehicular Technology
Issue number1
Publication statusPublished - 1 Jan 2016
MoE publication typeA1 Journal article-refereed


  • Beamforming
  • Full-duplex wireless communication
  • Multiple-input multiple-output (MIMO) systems
  • Relays
  • Selfinterference suppression


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