Uplink non-orthogonal multiple access for 5G wireless networks

Abstract

Orthogonal Frequency Division Multiple Access (OFDMA) as well as other orthogonal multiple access techniques fail to achieve the system capacity limit in the uplink due to the exclusivity in resource allocation. This issue is more prominent when fairness among the users is considered in the system. Current Non-Orthogonal Multiple Access (NOMA) techniques introduce redundancy by coding/spreading to facilitate the users' signals separation at the receiver, which degrade the system spectral efficiency. Hence, in order to achieve higher capacity, more efficient NOMA schemes need to be developed. In this paper, we propose a NOMA scheme for uplink that removes the resource allocation exclusivity and allows more than one user to share the same subcarrier without any coding/spreading redundancy. Joint processing is implemented at the receiver to detect the users' signals. However, to control the receiver complexity, an upper limit on the number of users per subcarrier needs to be imposed. In addition, a novel subcarrier and power allocation algorithm is proposed for the new NOMA scheme that maximizes the users' sum-rate. The link-level performance evaluation has shown that the proposed scheme achieves bit error rate close to the single-user case. Numerical results show that the proposed NOMA scheme can significantly improve the system performance in terms of spectral efficiency and fairness comparing to OFDMA.

Wireless-Powered Communications With Non-Orthogonal Multiple Access

“…For this reason, it has been recently proposed for LTE Advanced [20], in which it is termed as multi-user superposition transmission (MUST). Furthermore, it has also been recognized as a promising multiple access technique for fifth generation (5G) networks [21]- [24]. NOMA is substantially different from orthogonal multiple access schemes, i.e.…”

“…Also, in [24], the authors study NOMA for the uplink of a communication network, consisting of traditional nodes with fixed energy supplies. However, when NOMA is combined with wireless powered communications, the capacity region is strongly affected by the amount of the harvested energy.…”

“…The remaining time, T , is assigned to users, which simultaneously transmit their independent information to the BS by using the energy harvested from the first phase. In order to detect the users' signals, the BS implements a joint processing technique [22], [26], and for this purpose, it employs NOMA [24]. We assume that the energy transmitted by each user n is limited by the amount of harvested energy, i.e.…”

“…Therefore, for decoding the first user's message (n = 1), interference is created due to all other users n = 2, ..., N , while on the second user's message, interference is created due to users n = 3, ..., N , and so on. Then, the achievable throughput of the n-th user, 1 ≤ n ≤ (N − 1), denoted by R n in the case of fixed decoding order, is given by [24] R n =T log 2 …”

Dynamic Fractional Frequency Reuse Diversity Design for Intercell Interference Mitigation in Nonorthogonal Multiple Access Multicellular Networks

“…In recent years, many NOMA schemes have been devised such as interleave-division multiple access (IDMA) [7], low-density spreading CDMA (LDS-CDMA) [8], pattern-division multiple access (PDMA) [9][10][11][12][13][14], sparsecode multiple access (SCMA) [15][16][17], multiuser sharing access (MUSA) [18][19][20], bit-division multiplexing (BDM) [21], low-density spreading OFDM (LDS-OFDM) [22], resource-spread multiple access (RSMA) [23,24], interleavegrid multiple access (IGMA) [25], multiuser bit-interleaved coded modulation with iterative decoding (MU-BICM-ID) [26], and power domain nonorthogonal multiple access (PD-NOMA) [5,[27][28][29][30][31][32].…”