86 research outputs found
A NOMA-enhanced reconfigurable access scheme with device pairing for M2M networks
This paper aims to address the distinct requirements
of machine-to-machine networks, particularly heterogeneity and
massive transmissions. To this end, a reconfigurable medium
access control (MAC) with the ability to choose a proper access
scheme with the optimal configuration for devices based on
the network status is proposed. In this scheme, in each frame,
a separate time duration is allocated for each of the nonorthogonal multiple access (NOMA)-based, orthogonal multiple
access (OMA)-based, and random access-based segments, where
the length of each segment can be optimized. To solve this
optimization problem, an iterative algorithm consisting of two
sub-problems is proposed. The first sub-problem deals with
selecting devices for the NOMA/OMA-based transmissions, while
the second one optimizes the parameter of the random access
scheme. To show the efficacy of the proposed scheme, the results
are compared with the reconfigurable scheme which does not
support NOMA. The results demonstrate that by using a proper
device pairing scheme for the NOMA-based transmissions, the
proposed reconfigurable scheme achieves better performance
when NOMA is adopted
A Tutorial on Nonorthogonal Multiple Access for 5G and Beyond
Today's wireless networks allocate radio resources to users based on the
orthogonal multiple access (OMA) principle. However, as the number of users
increases, OMA based approaches may not meet the stringent emerging
requirements including very high spectral efficiency, very low latency, and
massive device connectivity. Nonorthogonal multiple access (NOMA) principle
emerges as a solution to improve the spectral efficiency while allowing some
degree of multiple access interference at receivers. In this tutorial style
paper, we target providing a unified model for NOMA, including uplink and
downlink transmissions, along with the extensions tomultiple inputmultiple
output and cooperative communication scenarios. Through numerical examples, we
compare the performances of OMA and NOMA networks. Implementation aspects and
open issues are also detailed.Comment: 25 pages, 10 figure
A Survey of Downlink Non-orthogonal Multiple Access for 5G Wireless Communication Networks
Accepted by ZTE CommunicationsAccepted by ZTE CommunicationsAccepted by ZTE CommunicationsAccepted by ZTE CommunicationsAccepted by ZTE CommunicationsNon-orthogonal multiple access (NOMA) has been recognized as a promising multiple access technique for the next generation cellular communication networks. In this paper, we first discuss a simple NOMA model with two users served by a single-carrier simultaneously to illustrate its basic principles. Then, a more general model with multicarrier serving an arbitrary number of users on each subcarrier is also discussed. An overview of existing works on performance analysis, resource allocation, and multiple-input multiple-output NOMA are summarized and discussed. Furthermore, we discuss the key features of NOMA and its potential research challenges
A Survey of Scheduling in 5G URLLC and Outlook for Emerging 6G Systems
Future wireless communication is expected to be a paradigm shift from three basic service requirements of 5th Generation (5G) including enhanced Mobile Broadband (eMBB), Ultra Reliable and Low Latency communication (URLLC) and the massive Machine Type Communication (mMTC). Integration of the three heterogeneous services into a single system is a challenging task. The integration includes several design issues including scheduling network resources with various services. Specially, scheduling the URLLC packets with eMBB and mMTC packets need more attention as it is a promising service of 5G and beyond systems. It needs to meet stringent Quality of Service (QoS) requirements and is used in time-critical applications. Thus through understanding of packet scheduling issues in existing system and potential future challenges is necessary. This paper surveys the potential works that addresses the packet scheduling algorithms for 5G and beyond systems in recent years. It provides state of the art review covering three main perspectives such as decentralised, centralised and joint scheduling techniques. The conventional decentralised algorithms are discussed first followed by the centralised algorithms with specific focus on single and multi-connected network perspective. Joint scheduling algorithms are also discussed in details. In order to provide an in-depth understanding of the key scheduling approaches, the performances of some prominent scheduling algorithms are evaluated and analysed. This paper also provides an insight into the potential challenges and future research directions from the scheduling perspective
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