Downlink Multi-Carrier NOMA With Opportunistic Bandwidth Allocations

Abstract

Multi-carrier non-orthogonal multiple access (MC-NOMA) system has been considered as a promising candidate in future wireless networks. In a MC-NOMA system, the available bandwidth of transmission is divided into several sub-bands, such that multiple users in each sub-band are served based on power-domain NOMA. Unlike the equal sub-band allocations, we propose a sum-rate maximization technique that jointly allocates the available power and bandwidth with opportunistic sharing between the sub-bands. A second-order cone program approach is exploited to deal with the non-convexity issues of the corresponding optimization problem. Simulation results reveal that the MC-NOMA system with opportunistic bandwidth allocation outperforms the scheme with the equal bandwidth allocation in terms of achieved sum-rate.Index Terms-Non-orthogonal multiple access (NOMA), Multicarrier NOMA.

Competitive IRS Assignment for IRS-Based NOMA System

“…It is assumed that the BS has the perfect channel state information (CSI) of all communication terminals through channel estimation methods. For such an IRS-free transmission, the achieved signal-to-noise-and interference ratio (SINR) for the IRS-free users (SINR ′ ) is similar to that of the users in conventional multi-carrier NOMA systems [10]. To be specific, the stronger user performs successive interference cancellation (SIC) in order to decode and subtract the signal of the weaker user with the SINR of:…”

“…2) IRS-assignment and Grouping Strategy: The proposed clustering strategy should be determined taking into account whether the cluster is IRS-free or IRS-assisted cluster. In particular, the proposed clustering approach for IRS-free clusters is similar to that in the conventional NOMA-based clustering approach [10]. Specifically, the users with diverse channel conditions are grouped, which allows for a successful SIC implementation.…”

“…We deal with the non-convexity problem in (7) by approximating each term with its first-order Taylor series expansion as follows: t) ), (10) where the superscript t denotes the t th iteration. Similarly, the constraint in ( 8) can be written as…”

Maximum Sum Rate of MCM-NOMA in Future Vehicular Sensor Networks

“…Another technology is non-orthogonal multiple access (NOMA), which allows multiple users to share the same time-frequency resources and can improve spectral efficiency and coverage. The performance analysis of MCM-NOMA in vehicular systems has motivated numerous studies, including a proposal for novel precoding method to reduce peakto-average power ratios [3], rate analysis [4]- [7], resource allocation optimization [6]- [8], and bit error rate analysis [9]- [11] among others. However, to the best of our knowledge, there has been no prior research that has analyzed the performance of MCM-NOMA systems in terms of sum rate and derived a closed-form expression for the rate of information transfer.…”

“…In [6], [7] sum rate maximization techniques are proposed. For instance, in [5] the authors derive expressions for the outage probability, bit error rate, and capacity with a two-user system model.…”