Linear Precoding Techniques for OFDM-Based NOMA over Frequency-Selective Fading Channels

ABSTRACT

Non-orthogonal multiple access (NOMA) is one of the potential candidates for future radio access to address the increasing demands of mobile traffic. NOMA-based systems employ orthogonal frequency division multiplexing (OFDM) for multicarrier modulation which induces peak-to-average power ratio (PAPR). High PAPR makes conventional NOMA systems spectrally and energy inefficient. Thus, in this paper, precoded NOMA system is proposed to overcome the PAPR problem in downlink NOMA. Different unitary transforms such as Walsh Hadamard transform (WHT), Zadoff chu transform (ZCT), and discrete Hartley transform are applied as linear precoding techniques to overcome the PAPR problem in NOMA. Moreover, a new precoding technique $T$-transform is also proposed which is a hybrid combination of WHT and ZCT. Link-level performance of power domain NOMA is analysed in terms of PAPR, spectral efficiency, bit error rate, and computational complexity. Simulation results show that in the presence of linear precoding techniques, performance of classic NOMA systems improve at the cost of slight increment in complexity.

KEYWORDS:

• Bit error rate
• Computational complexity
• Linear precoding
• Non-orthogonal multiple access
• Orthogonal frequency division multiplexing
• Peak-to-average power ratio
• Spectral efficiency
• Unitary transforms

ACKNOWLEDGMENTS

This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) and funded by the Ministry of Education [NRF 2015R1D1A1A01061075].

Additional information

Funding

Ministry of Science, ICT and Future Planning [IITP-2016-H8601-15-1011].

Notes on contributors

Arsla Khan

Arsla Khan was born in Lahore, Pakistan. She received her BS and MS degrees from COMSATS Institute of Information Technology (CIIT), Lahore, Pakistan, in Electrical Engineering in 2008 and 2012, respectively. Since 2008, she has been working as a lecturer in COMSATS Institute of Information Technology (CIIT), Lahore, Pakistan. She is currently pursuing the PhD degree with the Department of IT Convergence Engineering, School of Electronic Engineering, Kumoh National Institute of Technology (KIT), South Korea. Her research interests include power line communication for smart grid, multi-rate communication networks, and 5G.

E-mail: [email protected]

Soo Young Shin

Soo Young Shin received his BS, MS, and PhD degrees in Electrical Engineering and Computer Science from Seoul National University, Korea, in 1999, 2001, and 2006, respectively. His research interests include wireless LAN, WPAN, WBAN, wireless mesh network, sensor networks, coexistence among wireless networks, industrial and military network, cognitive radio networks, MIMO, OFDM, mmWave, NOMA, and next-generation mobile wireless broadband networks (4G/5G). He was a visiting scholar in FUNLab at University of Washington, Seattle, USA, from July 2006 to June 2007. After three years working in WiMAX design lab of Samsung Electronics, he is now an assistant professor in School of Electronics in Kumoh National Institute of Technology since September 2010.

E-mail: [email protected]