Resource allocation method for improved spectral efficiency, outage probability and user fairness in NOMA

ABSTRACT

Non- Orthogonal Multiple Access (NOMA) is one of the evolving and potential multiple access schemes in wireless networks to improve connection, spectrum efficiency, cell-edge throughput, and user fairness. As Spectral Efficiency (SE) is an important factor in data transmission to the user, in this paper the Least Sub-carrier Sum-Gain-based User Assignment Algorithm (LSSGUA) and Inter- and Intra-level Power Allocation (PA) algorithms for the Multi-Carrier (MC) Down-Link (DL)-NOMA are proposed to enhance the SE and allocate power to each sub-carrier/user. In LSSGUA, the channel gain of each sub-carrier/sub-channel is added and the sub-carrier with the least channel gain is given priority. In the case of the inter-level PA algorithm, the gain of the assigned users of each sub-carrier is added and the power allocated to each sub-carrier is in an ascending manner so that the sub-carrier with the worst channel gain of the assigned users is allocated with the highest power using Worst Sub-carrier First Algorithm (WSFA). In the intra-level PA algorithm, the iterative algorithm Bisection Method (BM) allocates power to each user. Simulation results show that the suggested algorithms improved the sum rate, SE, fairness performance, and outage probabilities when compared to the existing NOMA Resource Allocation (RA) scheme.

KEYWORDS:

• NOMA
• channel assignment
• power allocation
• spectral efficiency
• user fairness

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1. Elements of $Q$ and $P$ are the optimization variables.

2. Poor channel gain indicated in a single underline.

3. Best channel gain indicated in double underline.

4. NOMA-WSFA-BM indicates LSSGUA + inter + intra PA.

5. NOMA-EQ-FTPA indicates WCUFSA + Equal Power + Fractional Transmit Power Allocation.

6. In Tables 1 and 2 Power left (row) indicates the preserved power in each sub-carrier (Watt).