Comparison study of non-orthogonal multiple access schemes for 5G

Abstract

With the development of mobile Internet and Internet of things (IoT), the 5th generation (5G) wireless communications will foresee explosive increase in mobile traffic. To address challenges in 5G such as higher spectral efficiency, massive connectivity, and lower latency, some non-orthogonal multiple access (NOMA) schemes have been recently actively investigated, including power-domain NOMA, multiple access with low-density spreading (LDS), sparse code multiple access (SCMA), multiuser shared access (MUSA), pattern division multiple access (PDMA), etc. Different from conventional orthogonal multiple access (OMA) schemes, NOMA can realize overloading by introducing some controllable interferences at the cost of slightly increased receiver complexity, which can achieve significant gains in spectral efficiency and accommodate much more users. In this paper, we will discuss basic principles and key features of three typical NOMA schemes, i.e., SCMA, MUSA, and PDMA. What's more, their performance in terms of uplink bit error rate (BER) will be compared. Simulation results show that in typical Rayleigh fading channels, SCMA has the best performance, while the BER performance of MUSA and PDMA are very close to each other. In addition, we also analyze the performance of PDMA using the same factor graph as SCMA, which indicates that the performance gain of SCMA over PDMA comes from both the difference of factor graph and the codebook optimization.

Efficient 5G Communication System using Random Access Block Interleaving with ETU Channel

“…For the kth subscriber, the interference from other subscribers can be seen as a part of noise. Therefore, the above equation can be written as [1]: Science & Technology, Bhopal by a specific coefficient. Then, Successive Interference Cancellation (SIC) is employed at the receiver device (or UE in the LTE context).…”

“…Random Access Block Interleaving performs better because it employs a low complexity chip-by-chip iterative MUD technique on systems with quite a large number of subscribers. Here, the normalized MUD cost per subscriber doesn't depend on the number of subscribers in the system [1].…”

“…Random Access Block Interleaving uses an Elementary Signal Estimator (ESE) and single subscriber a-posteriori probability (APP) decoders (DEC) [1]. The work of ESE is to find a joint solution considering all subscribers and hence the complexity per subscriber depends on the number of subscribers.…”

“…The work of ESE is to find a joint solution considering all subscribers and hence the complexity per subscriber depends on the number of subscribers. DEC, on the other hand, handles data only for one subscriber, so its complexity per subscriber is not dependent on subscriber count [1].The ESE as well as DEC blocks estimate about x_i (m) and their outputs are extrinsic log-likelihood ratios (LLR) given as [1], [10] e൫x ୧ ሺmሻ൯ ൌ logሺ pሺy|x ୧ ሺmሻ ൌ 1ሻ pሺy|x ୧ ሺmሻ ൌ −1ሻ ሻ ∀ i, m e ୗ ሺx ୧ ሺmሻሻ is the LLR output from ESE block and e ୈେ ሺx ୧ ሺmሻሻ is the LLR output from DEC block.…”

Interference cancellation for non-orthogonal multiple access used in future wireless mobile networks

“…However, due to the vastly increased need for high-volume services, such as image transfer, video streaming, and cloud-based services, a new mobile communications system with further enhancement of system throughput is required for the nextgeneration (5G) mobile communication systems. In order to fulfill such requirements, non-orthogonal multiple access (NOMA) with a successive interference cancellation (SIC) receiver in downlink was presented as one of several promising candidate radio access technologies [4][5][6][7][8][9][10]. For downlink NOMA, non-orthogonality is achieved by introducing the power domain, either in time/frequency/code domains, for user multiplexing.…”