Improving Cell-Edge User Performance Using Power Control in CoMP-Enabled NOMA Network under Random User Pairing Scenario.

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Name of the Speaker: Asif Ikbal Mondal (EE19S014)
Name of the Guide: Dr. Manivasakan R
Date/Time: Monday, August 22 · 3:00 – 4:00pm

Non-orthogonal multiple access (NOMA) is a major 5G technology that leverages resources in a non-orthogonal way to improve the spectral efficiency and number of user connections in a wireless network. One of the key issues with the multi-cell NOMA system is that cell-edge users may experience lower bit rates due to inter-cell interference (ICI) from nearby cells. Although joint transmission coordinated multi-point (JT-CoMP) transmission can help to mitigate this problem, cell-edge users' performance is limited by inter-NOMA-user interference (INUI) from users in the same resource block (RB) as the cell-edge user. In our study, we have considered a two-cell JT-CoMP-NOMA system where the cell-edge user is paired with another user in each NOMA cell on the same RB.

The INUI to cell-edge user is more severe when the channel gain difference between users is not significant (in case of random user pairing). In order to utilize the coordination among base stations fully, this paper proposes a downlink Transmit Power Control (TPC) scheme for a JT-CoMP-NOMA system. The power control method aims to minimize the INUI to the cell-edge user subject to the data rate and allocated power constraints of other users in the same RB. We propose a linear programming problem (LPP) to minimize the INUI and solve the LPP using the efficient interior-point method (IPM) in MATLAB. Furthermore, we have derived a closed-form expression for the outage probability of cell-edge user considering fixed transmit power allocation.

Computer simulation results are provided to compare the performance of the proposed TPC scheme as well as to demonstrate the accuracy of the analytical result.