64 research outputs found
V2X Meets NOMA: Non-Orthogonal Multiple Access for 5G Enabled Vehicular Networks
Benefited from the widely deployed infrastructure, the LTE network has
recently been considered as a promising candidate to support the
vehicle-to-everything (V2X) services. However, with a massive number of devices
accessing the V2X network in the future, the conventional OFDM-based LTE
network faces the congestion issues due to its low efficiency of orthogonal
access, resulting in significant access delay and posing a great challenge
especially to safety-critical applications. The non-orthogonal multiple access
(NOMA) technique has been well recognized as an effective solution for the
future 5G cellular networks to provide broadband communications and massive
connectivity. In this article, we investigate the applicability of NOMA in
supporting cellular V2X services to achieve low latency and high reliability.
Starting with a basic V2X unicast system, a novel NOMA-based scheme is proposed
to tackle the technical hurdles in designing high spectral efficient scheduling
and resource allocation schemes in the ultra dense topology. We then extend it
to a more general V2X broadcasting system. Other NOMA-based extended V2X
applications and some open issues are also discussed.Comment: Accepted by IEEE Wireless Communications Magazin
Uplink Contention Based SCMA for 5G Radio Access
Fifth generation (5G) wireless networks are expected to support very diverse
applications and terminals. Massive connectivity with a large number of devices
is an important requirement for 5G networks. Current LTE system is not able to
efficiently support massive connectivity, especially on the uplink (UL). Among
the issues arise due to massive connectivity is the cost of signaling overhead
and latency. In this paper, an uplink contention-based sparse code multiple
access (SCMA) design is proposed as a solution. First, the system design
aspects of the proposed multiple-access scheme are described. The SCMA
parameters can be adjusted to provide different levels of overloading, thus
suitable to meet the diverse traffic connectivity requirements. In addition,
the system-level evaluations of a small packet application scenario are
provided for contention-based UL SCMA. SCMA is compared to OFDMA in terms of
connectivity and drop rate under a tight latency requirement. The simulation
results demonstrate that contention-based SCMA can provide around 2.8 times
gain over contention-based OFDMA in terms of supported active users. The uplink
contention-based SCMA scheme can be a promising technology for 5G wireless
networks for data transmission with low signaling overhead, low delay, and
support of massive connectivity.Comment: Submitted to Golobecom 5G workshop 201
Uplink Contention Based SCMA for 5G Radio Access
Abstract Fifth generation (5G) wireless networks are expected to support very diverse applications and terminals. Massive connectivity with a large number of devices is an important requirement for 5G networks. Current LTE system is not able to efficiently support massive connectivity, especially on the uplink (UL). Among the issues that arise due to massive connectivity is the cost of signaling overhead and latency. In this paper, an uplink contention-based sparse code multiple access (SCMA) design is proposed as a solution. First, the system design aspects of the proposed multiple-access scheme are described. The SCMA parameters can be adjusted to provide different levels of overloading, thus suitable to meet the diverse traffic connectivity requirements. In addition, the system-level evaluations of a small packet application scenario are provided for contention-based UL SCMA. SCMA is compared to OFDMA in terms of connectivity and drop rate under a tight latency requirement. The simulation results demonstrate that contention-based SCMA can provide around 2.8 times gain over contention-based OFDMA in terms of supported active users. The uplink contention-based SCMA scheme can be a promising technology for 5G wireless networks for data transmission with low signaling overhead, low delay, and support of massive connectivity
Non-orthogonal multiple access for machine-type communications toward 6G
Abstract. Massive machine-type communications (mMTC) is one of the main focus areas in the fifth generation of wireless communications. It is also the fastest-growing field in terms of the number of devices. The massive increase in devices connected to the internet and global data traffic creates unprecedented requirements for future generations of wireless communications. One of the key technologies for the performance of the system is the utilized multiple access (MA) scheme. The conventional orthogonal MA (OMA) schemes from the earlier generations fail to satisfy the increasing demands for connectivity and spectral efficiency. On the contrary, non-orthogonal MA (NOMA) schemes offer the connectivity and spectral efficiency needed to enable mMTC. NOMA does this by allowing multiple users to transmit their data through the same resource blocks (RBs) simultaneously. NOMA is generally divided into two categories, namely power domain (PD-) NOMA and code domain (CD-) NOMA. PD-NOMA utilizes the power domain for the multiplexing, whereas CD-NOMA uses the code domain. This thesis focuses on the fundamentals of NOMA, MTC, and what NOMA can offer to MTC. We will also discuss the challenges and open problems that need to be solved. Finally, the thesis includes some simulations that demonstrate NOMA in practice.Ei-ortogonaalinen monikäyttö kone-tyyppisessä kommunikaatiossa kohti 6G:tä. Tiivistelmä. Massiivinen kone-tyyppinen kommunikaatio (mMTC) on yksi viidennen sukupolven langattoman viestinnän pääpainopisteistä. Se on myös nopeimmin kasvava osa-alue, kun katsotaan laitteiden lukumäärää. Internetiin yhdistettyjen laitteiden ja globaalin tietoliikenteen valtava kasvu luo ennennäkemättömiä vaatimuksia tuleville langattoman viestinnän sukupolville. Yksi avainteknologioista järjestelmän suorituskyvyn kannalta on käytetty monikäyttömenetelmä (MA). Tavanomaiset ortogonaaliset MA (OMA) -järjestelmät eivät saavuta yhdistettävyyden ja spektritehokkuuden kasvavia vaatimuksia. Sitä vastoin ei-ortogonaaliset MA (NOMA) -järjestelmät tarjoavat mMTC:n mahdollistamiseen tarvitun yhdistettävyyden ja spektritehokkuuden. NOMA saavuttaa tämän sallimalla usean käyttäjän lähettää dataa saman resurssilohkon kautta samanaikaisesti. NOMA voidaan yleisesti jakaa kahteen kategoriaan, tehoalueen NOMA:an ja koodialueen NOMA:an. Tämä työ keskittyy NOMA:n ja MTC:n perusteisiin ja siihen, mitä NOMA voi tarjota MTC-käyttökohteille. Työssä käydään myös läpi ratkaisuja vaativat haasteet ja avoimet ongelmat. Lopuksi työ sisältää simulaatioita, jotka mallintavat NOMA:n toimintaa käytännössä
Signal Processing and Learning for Next Generation Multiple Access in 6G
Wireless communication systems to date primarily rely on the orthogonality of
resources to facilitate the design and implementation, from user access to data
transmission. Emerging applications and scenarios in the sixth generation (6G)
wireless systems will require massive connectivity and transmission of a deluge
of data, which calls for more flexibility in the design concept that goes
beyond orthogonality. Furthermore, recent advances in signal processing and
learning have attracted considerable attention, as they provide promising
approaches to various complex and previously intractable problems of signal
processing in many fields. This article provides an overview of research
efforts to date in the field of signal processing and learning for
next-generation multiple access, with an emphasis on massive random access and
non-orthogonal multiple access. The promising interplay with new technologies
and the challenges in learning-based NGMA are discussed
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