Interference Alignment - (for Interference Channels)

201 Pages·2011·6.36 MB·English

Interference Alignment
(for Interference Channels)
Bobak Nazer, Boston University
Wireless Information Theory Summer School
University of Oulu
July 28, 2011
Outline
I. K-User Interference Channels
II. Alignment via Linear Precoding
III. Ergodic Alignment
IV. Lattice Alignment for Fixed Channels
K-User Interference Channel
1 1
2 2
K-User Interference Channel
1 1
2 2
K K
• K transmitter-receiver pairs share a common wireless channel.
K-User Interference Channel
1 1
H
2 2
K K
• K transmitter-receiver pairs share a common wireless channel.
• Receivers observe noisy linear combinations of transmitted signals:
K
Y = h X +Z
k kℓ ℓ k
ℓ=1
X
K-User Interference Channel
1 1
h h ··· h
11 12 1K
h h ··· h
21 22 2K
2 2
... ... ... ...
h h ··· h
K1 K2 KK
K K
• K transmitter-receiver pairs share a common wireless channel.
• Receivers observe noisy linear combinations of transmitted signals:
K
Y = h X +Z
k kℓ ℓ k
ℓ=1
X
Strong Interference
1 1
2 2
K K
Strong Interference
1 1
2 2
K K
Strong Interference
1 1
2 2
K K
• Strategy: First, decode and subtract interfering signals. Then,
recover desired codeword.
Strong Interference
1 1
2 2
K K
• Strategy: First, decode and subtract interfering signals. Then,
recover desired codeword.
• Optimal if interference is very strong.
(Carleial ’75, Sato ’81, Han-Kobayashi ’81, Sankar-Erkip-Poor ’08)