TY - JOUR
T1 - Enhanced Multiuser Superposition Transmission Through Structured Modulation
AU - Fang, Dong
AU - Huang, Yu Chih
AU - Geraci, Giovanni
AU - Ding, Zhiguo
AU - Claussen, Holger
N1 - Funding Information:
Manuscript received February 23, 2018; revised August 14, 2018; accepted March 14, 2019. Date of publication April 4, 2019; date of current version May 8, 2019. The work of Y.-C. Huang was supported by the Ministry of Science and Technology of Taiwan under Grant MOST 106-2628-E-305-001-MY3. The work of G. Geraci was supported in part by the Postdoctoral Junior Leader Fellowship Programme from the “la Caixa” Banking Foundation. This paper was presented in part at the IEEE Globecom 2016 [1] and at the IEEE VTC Spring 2017 [2]. The associate editor coordinating the review of this paper and approving it for publication was P. Minero. (Corresponding author: Dong Fang.) D. Fang was with Nokia Bell Labs, Dublin, D15 Y6NT Ireland. He is now with the UnitedHealth Group, Dublin, D01 X9R7 Ireland (e-mail: [email protected]).
Publisher Copyright:
© 2018 IEEE.
PY - 2019/5
Y1 - 2019/5
N2 - The fifth-generation (5G) air interface, namely, dynamic multiple access (MA) based on multiuser superposition transmission (MUST) and orthogonal MA (OMA), may require a complicated scheduling and heavy signaling overhead. To address these challenges, we propose a unified MA scheme for future cellular networks, which we refer to as structured MUST (S-MUST). In S-MUST, we apply complex power allocation coefficients (CPACs) over multiuser legacy constellations to generate a composite constellation. In particular, the in-phase (I) and quadrature (Q) components of the legacy constellation of each user are separately multiplied by those of the CPACs. As such, the CPACs offer an extra degree of freedom for multiplexing users and guarantee fairness in symmetric broadcast channels. This new paradigm of superposition coding allows us to design I separation at the user side, which significantly reduces the decoding complexity without degrading performance. Hence, it supports low-complexity frequency-selective scheduling that does not entail dynamical switching between MUST and OMA. We further propose to quantize the CPACs into complex numbers where I and Q components of each quantized coefficient are primes, facilitating parallel interference cancellation at each user via modulo operations; last but not least, we generalize the design of S-MUST to exploit the capabilities of multiantenna base stations. The proposed S-MUST exhibits an improved user fairness with respect to conventional MUST (134% spectral efficiency enhancement) and a lower system complexity compared with dynamically alternating MUST and OMA.
AB - The fifth-generation (5G) air interface, namely, dynamic multiple access (MA) based on multiuser superposition transmission (MUST) and orthogonal MA (OMA), may require a complicated scheduling and heavy signaling overhead. To address these challenges, we propose a unified MA scheme for future cellular networks, which we refer to as structured MUST (S-MUST). In S-MUST, we apply complex power allocation coefficients (CPACs) over multiuser legacy constellations to generate a composite constellation. In particular, the in-phase (I) and quadrature (Q) components of the legacy constellation of each user are separately multiplied by those of the CPACs. As such, the CPACs offer an extra degree of freedom for multiplexing users and guarantee fairness in symmetric broadcast channels. This new paradigm of superposition coding allows us to design I separation at the user side, which significantly reduces the decoding complexity without degrading performance. Hence, it supports low-complexity frequency-selective scheduling that does not entail dynamical switching between MUST and OMA. We further propose to quantize the CPACs into complex numbers where I and Q components of each quantized coefficient are primes, facilitating parallel interference cancellation at each user via modulo operations; last but not least, we generalize the design of S-MUST to exploit the capabilities of multiantenna base stations. The proposed S-MUST exhibits an improved user fairness with respect to conventional MUST (134% spectral efficiency enhancement) and a lower system complexity compared with dynamically alternating MUST and OMA.
KW - Multiuser superposition transmission
KW - non-orthogonal multiple access
KW - superposition coding
UR - http://www.scopus.com/inward/record.url?scp=85065561596&partnerID=8YFLogxK
U2 - 10.1109/TWC.2019.2908157
DO - 10.1109/TWC.2019.2908157
M3 - Article
AN - SCOPUS:85065561596
SN - 1536-1276
VL - 18
SP - 2765
EP - 2776
JO - IEEE Transactions on Wireless Communications
JF - IEEE Transactions on Wireless Communications
IS - 5
M1 - 8681742
ER -