Multiple Access for 5G New Radio: Categorization, Evaluation, and Challenges

Abstract

Next generation wireless networks require massive uplink connections as well as high spectral efficiency. It is well known that, theoretically, it is not possible to achieve the sum capacity of multi-user communications with orthogonal multiple access. To meet the challenging requirements of next generation networks, researchers have explored non-orthogonal and overloaded transmission technologies-known as new radio multiple access (NR-MA) schemes-for fifth generation (5G) networks. In this article, we discuss the key features of the promising NR-MA schemes for the massive uplink connections. The candidate schemes of NR-MA can be characterized by multiple access signatures (MA-signatures), such as codebook, sequence, and interleaver/scrambler. At the receiver side, advanced multiuser detection (MUD) schemes are employed to extract each user's data from non-orthogonally superposed data according to MA-signatures. Through link-level simulations, we compare the performances of NR-MA candidates under the same conditions. We further evaluate the sum rate performances of the NR-MA schemes using a 3-dimensional (3D) ray tracing tool based system-level simulator by reflecting realistic environments. Lastly, we discuss the tips for system operations as well as call attention to the remaining technical challenges.

Clustering Approach for Reliable Wireless Communication

“…Sci. 2024, 14, x FOR PEER REVIEW 3 of 20 [49], another three CD-NOMA multiple access techniques were compared by evaluating the BER behavior when the signal-to-noise ratio (SNR) varies-using MUSA, SCMA, and IDMA. An uplink SISO connection is considered when data from up to 24 users are QPSKmodulated, orthogonal frequency-division multiplexed (OFDM), and when the data are altered by Rayleigh fading on the communication channel.…”

Optimized Resource Provisioning and Operation Control for Low-power Wide-area IoT Networks

“…In literature, nonorthogonal access has been employed in order to increase the network throughput [11], reliability [12], battery lifetime [13], and reduce delay [11]. A through survey of non-orthogonal radio access nominated for 5G can be found in [14], which categorizes the available schemes into three categories: (i) codebook-based multiple access, with codebooks in power or code domain like sparse code and pattern division multiple access (SCMA, PDMA); (ii) sequence-based multiple-access, using complex number sequences like multi-user shared access (MUSA) and non-orthogonal coded multiple access (NCMA); and (iii) interleaver/scrambler-based multiple access like resource spread multiple access (RSMA). Among these schemes, MUSA and RSMA can be used in an asynchronous and grantfree mode, and RSMA has been proposed as a candidate for grant-free access in future LTE releases [15].…”