166 research outputs found
Capacity-Achieving Iterative LMMSE Detection for MIMO-NOMA Systems
This paper considers a iterative Linear Minimum Mean Square Error (LMMSE)
detection for the uplink Multiuser Multiple-Input and Multiple-Output (MU-MIMO)
systems with Non-Orthogonal Multiple Access (NOMA). The iterative LMMSE
detection greatly reduces the system computational complexity by departing the
overall processing into many low-complexity distributed calculations. However,
it is generally considered to be sub-optimal and achieves relatively poor
performance. In this paper, we firstly present the matching conditions and area
theorems for the iterative detection of the MIMO-NOMA systems. Based on the
proposed matching conditions and area theorems, the achievable rate region of
the iterative LMMSE detection is analysed. We prove that by properly design the
iterative LMMSE detection, it can achieve (i) the optimal sum capacity of
MU-MIMO systems, (ii) all the maximal extreme points in the capacity region of
MU-MIMO system, and (iii) the whole capacity region of two-user MIMO systems.Comment: 6pages, 5 figures, accepted by IEEE ICC 2016, 23-27 May 2016, Kuala
Lumpur, Malaysi
Capacity-Achieving MIMO-NOMA: Iterative LMMSE Detection
This paper considers a low-complexity iterative Linear Minimum Mean Square
Error (LMMSE) multi-user detector for the Multiple-Input and Multiple-Output
system with Non-Orthogonal Multiple Access (MIMO-NOMA), where multiple
single-antenna users simultaneously communicate with a multiple-antenna base
station (BS). While LMMSE being a linear detector has a low complexity, it has
suboptimal performance in multi-user detection scenario due to the mismatch
between LMMSE detection and multi-user decoding. Therefore, in this paper, we
provide the matching conditions between the detector and decoders for
MIMO-NOMA, which are then used to derive the achievable rate of the iterative
detection. We prove that a matched iterative LMMSE detector can achieve (i) the
optimal capacity of symmetric MIMO-NOMA with any number of users, (ii) the
optimal sum capacity of asymmetric MIMO-NOMA with any number of users, (iii)
all the maximal extreme points in the capacity region of asymmetric MIMO-NOMA
with any number of users, (iv) all points in the capacity region of two-user
and three-user asymmetric MIMO-NOMA systems. In addition, a kind of practical
low-complexity error-correcting multiuser code, called irregular
repeat-accumulate code, is designed to match the LMMSE detector. Numerical
results shows that the bit error rate performance of the proposed iterative
LMMSE detection outperforms the state-of-art methods and is within 0.8dB from
the associated capacity limit.Comment: Accepted by IEEE TSP, 16 pages, 9 figures. This is the first work
that proves the low-complexity iterative receiver (Parallel Interference
Cancellation) can achieve the capacity of multi-user MIMO systems. arXiv
admin note: text overlap with arXiv:1604.0831
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