Enhanced Uplink Resource Allocation in Non-Orthogonal Multiple Access Systems

Abstract

Abstract-Non-orthogonal multiple access (NOMA) is envisioned to be one of the most beneficial technologies for next generation wireless networks due to its enhanced performance compared to other conventional radio access techniques. Although the principle of NOMA allows multiple users to use the same frequency resource, due to decoding complication, information of users in practical systems cannot be decoded successfully if many of them use the same channel. Consequently, assigned spectrum of a system needs to be split into multiple subchannels in order to multiplex that among many users. Uplink resource allocation for such systems is more complicated compared to the downlink ones due to the individual users' power constraints and discrete nature of subchannel assignment. In this paper, we propose an uplink subchannel and power allocation scheme for such systems. Due to the NP-hard and non-convex nature of the problem, the complete solution, that optimizes both subchannel assignment and power allocation jointly, is intractable. Consequently, we solve the problem in two steps. First, based on the assumption that the maximal power level of a user is subdivided equally among its allocated subchannels, we apply many-to-many matching model to solve the subchannel-user mapping problem. Then, in order to enhance the performance of the system further, we apply iterative water-filling and geometric programming two power allocation techniques to allocate power in each allocated subchannel-user slot optimally. Extensive simulation has been conducted to verify the effectiveness of the proposed scheme. The results demonstrate that the proposed scheme always outperforms all existing works in this context under all possible scenarios.

Energy Efficiency Optimization for NOMA With SWIPT

“…However, in an OFDMA-based system, each subcarrier is only occupied by a single terminal in spite of the channel conditions, which limits the achievable SE. On the other hand, non-orthogonal multiple access (NOMA) can further improve the SE as each subcarrier is allowed to serve multiple terminals at the same time [3], and hence it has received considerable attention as a promising candidate for 5G [4]- [9]. Sharing the same spectrum among users leads to a high mutual interference when decoding information.…”

Efficient Allocation for Downlink Multi-Channel NOMA Systems Considering Complex Constraints

“…The detailed parameter configurations are presented in Table 1 . The sub-channel is configured to have 200 kHz bandwidth [ 40 ]. The power budget configurations refer to Fang et al [ 9 ], where the power budget for sub-channel is averaged on 30 dBm, and the power budget for users is averaged on 40 dBm.…”

Fair Energy-Efficient Resource Allocation for Downlink NOMA Heterogeneous Networks

“…In line with this objective, several studies proposed to address the resource allocation problems in single-cell scenarios. The power allocation solutions were introduced to maximize the sumrate for PD-NOMA system in uplink transmission [25], [26], downlink transmission [27], [28], and both uplink and downlink transmission [29]. Besides, the power allocation solutions have also been proposed to maximize the energy efficiency for the downlink PD-NOMA system in [30]- [34].…”