Wireless MIMO switching with trusted and untrusted relays: Degrees of freedom perspective

Fanggang Wang, Xiaojun Yuan, Jemin Lee, Tony Q.S. Quek

Research output: Chapter in Book/Report/Conference proceedingConference contribution

5 Citations (Scopus)


We investigate the degrees of freedom (DoF) and secrecy DoF for a general framework of multiway relay networks named wireless MIMO switching, where a number of users exchange information via a common relay. Each round of data exchange consists of one uplink transmission from users to relay and one downlink transmission from relay back to users. The data exchange model is unicast, i.e., every user transmits one message and intends to receive one message from one other user. We categorize unicast patterns using the notion of orbit borrowed from abstract algebra. Roughly speaking, an orbit is a minimum subset of users such that data exchange is closed within this subset. We analyze the achievable DoF of wireless MIMO switching with various numbers of orbits. Particularly, the DoF capacity for unicast with one and two orbits are established. Furthermore, we study communication secrecy with an untrusted relay in wireless MIMO switching. We present an achievable secrecy sum rate and the corresponding achievable secrecy DoF by assuming a non-regenerative relay. Then, we focus on unicast patterns with one and two orbits, and show that this achievable lower bound is actually the secrecy DoF capacity based on a novel genie-aided technique. Our results build a bridge between the DoF and the secrecy DoF in multiway relaying. The methodology of the proof can be generally applied to analyze the secrecy DoF in other relay networks.

Original languageEnglish
Title of host publication2015 IEEE International Conference on Communications, ICC 2015
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages6
ISBN (Electronic)9781467364324
Publication statusPublished - 2015 Sep 9
EventIEEE International Conference on Communications, ICC 2015 - London, United Kingdom
Duration: 2015 Jun 82015 Jun 12

Publication series

NameIEEE International Conference on Communications
ISSN (Print)1550-3607


OtherIEEE International Conference on Communications, ICC 2015
Country/TerritoryUnited Kingdom

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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