Applications of Power-Domain Non-Orthogonal Multiple Access in Wireless Communication Networks

• Author / Creator

  Li,Guoxin

• The expected explosive data traffic and scarcity of available spectrum in wireless networks place higher demands on spectrum utilization. As one of the advanced techniques for improving spectral efficiency, non-orthogonal multiple access (NOMA) has raised considerable
  attention recently. Although many works have been conducted to demonstrate the advantages of NOMA in various communication scenarios, there are still some open problems. Our research attempts to fill some research gaps by investigating protocol design, resource allocation, and performance analysis for the applications of power-domain NOMA in cooperative networks, cognitive radio networks, and wireless powered networks.

  We first investigate how to enjoy the benefits of cooperative technique for NOMA-based systems while addressing the possible loss of spectral efficiency caused by the fixed relaying. Due to the constraint of half-duplex, the relay needs to occupy half of the transmission block to forward information. Therefore, cooperative NOMA networks may suffer a loss of spectral efficiency if the relay always participates in the cooperation. To solve this concern, we propose an incremental cooperative NOMA protocol in which the relay is invoked for cooperation in a more reasonable way.

  We next study an overlay cognitive NOMA network which can be treated as a type of NOMA networks with user priority difference. In this type of networks, how to improve the performance of the lower-priority user while ensuring the quality-of-service requirements of the higher-priority user becomes an appropriate research target, which is quite different from the conventional NOMA networks where sum rate or user fairness is more concerned. This observation motivates us to study the joint optimal design of power allocation and decoding order suitable for overlay cognitive NOMA networks. Specifically, we propose two joint optimal strategies based on the availability of channel state information at the transmitter.

  We then solve two optimization problems in a cooperative NOMA network with simultaneous wireless information and power transfer. Different from current works where the solely power-splitting (PS) or the solely time-splitting (TS) scheme is employed to harvest energy, we assume that the energy-constrained relay employs the hybrid PS and TS scheme to harvest energy since the hybrid PS and TS scheme is expected to outperform the PS and the TS schemes by exploiting both the degree-of-freedom in the time and power domains. Depending on the availability of channel state information at the transmitter, we successfully address two optimization problems which realize maximization of energy efficiency and minimization of system outage probability, respectively.

  Finally, we address a fair resource allocation problem involved in a power beacon-assisted downlink NOMA network. In this network, the energy-constrained source first collects energy from the power beacon and then uses it to communicate with a pair of users. By designing an alternating optimization algorithm based on the statistical channel state information, we successfully obtain the joint optimal time allocation and power allocation ratios that can maximize the worse throughput of the paired users.

• Subjects / Keywords

  • energy harvesting
  • non-orthogonal multiple access
  • spectral efficiency
  • cooperative communication

• Graduation date

  Spring 2020

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-d3nd-9r57

• License

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