Topic
On Feasibility of Linear Interference Alignment with Symbol Extension for Two-Cell MIMO Interfering
Multiple Access Channel
Abstract
Interfering multiple access channel (IMAC) consists of several traditional multiple access channels (MAC)
that interfere with each other, and IMAC is of practical importance because it models the environment of
the uplink communications of several adjacent cells. To study the interference management of the cellular
networks, researchers have applied linear interference alignment scheme to IMAC to obtain the optimal
integer degrees of freedoms (DoF) of the channel, while the issue of non-integer DoF is less addressed in
the literature.
In this talk, we will explore the non-integer degrees of freedoms (DoF) of the time-invariant
multiple-input multiple-output (MIMO) interfering multiple access channel (IMAC) in the simple setting
of two cells, K users per cell, and M antennas at all nodes. We apply the idea of channel diversity
developed by Li, Jafarkhani, and Jafar to this setting to derive the exact characterization of the maximum
achievable sum DoF under the constraint of using linear interference alignment (IA) scheme. We show
that the sum DoF characterization 2MK/(1 + K) provided by the linear IA scheme only holds for K ≤ M2.
Symbol extension is applied to the linear IA scheme for the achievability of the non-integer DoF, and the
upper bound is constructed by using the block-diagonal structure of the extended channel matrix, where
all blocks are the same.
Bio
Chiachi Huang received the B.S. degree in electrical engineering from Yuan Ze University, Taoyuan,
Taiwan, in 1999, the M.S. degree in communications engineering from National Tsing Hua University,
Hsingchu, Taiwan, in 2001, and the Ph.D. degree in electrical engineering from the University of
California at Irvine, California, USA, in 2009. Since 2009, he has been with the Department of
Communications Engineering at Yuan Ze University, Taoyuan, Taiwan, as an Assistant Professor. His
research interests include multiuser information theory, wireless communications, and MIMO networks.
He received the Best Paper Award for Young Authors from the IEEE Information Theory and
Communication Societies Taipei/Tainan Chapter in 2013.