Special Topic Seminar on
Power Domain Non- Orthogonal Multiple
Access(NOMA)
Presented by: Ms. Natasha Naik( Research Scholar, RGIT)
Supervisor: Dr. Sanjay Deshmukh( Vice Principal & HoD EXTC, RGIT)
CONTENTS
INTRODUCTION TO NOMA
WHY NOMA?
OVERVIEW and MOTIVATION
BASICS OF NOMA
COMPARISON OF OMA AND NOMA
NOMA SCHEMES
UPLINK AND DOWNLINK NOMA NETWORK
BASIC NOMA
COOPERATIVE NOMA
NOMA IN MIMO SYSTEMS
CONTENTS
ADVANTAGES OF NOMA
DISADVANTAGES OF NOMA
APPLICATIONS OF NOMA
ACTIVE RESEARCH AREAS
REFERENCES
Features of
Generations
1G
2G
3G
4G
5G
Duration
1970-1980
1990- 2000
2004-2005
2011
Around 2020
Data rates
2kbps
64kbps
2Mbps
1Gbps
>1Gbps
Technologies
Analog
cellular,AMPS
,NMT
Digital
Cellular
WCDMA,CDMA
2000, EDGE,
UMTS
Wi-Fi, WiMax
LTE
Unified IP
seamless
combination of
broadband
Service
Analog voice
no data
service
Digital
voice,
SMS,MMS
Faster
communication,
Audio/Video
data in better
quality
Wearable
devices,mobile
multimedia,dyn
amic
information
access
Wearable
device with AI
capability, 3D
gaming, video
streaming
Multiplexing
FDMA
TDMA,
CDMA
CDMA
OFDMA
NOMA
INTRODUCTION TO NOMA
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NOMA is an emerging technology for the fifth generation wireless networks which can address the
requirements of 5G.
The key idea behind NOMA is to serve multiple users with power multiplexing.
NOMA brings a step change in data speed and a significant reduction in end to end latency.
It uses Superposition coding at the transmitter and Successive Interference Cancellation at the receiver.
Why NOMA?
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Orthogonal multiple access has been used during the past (1G-4G) as follows:
FDMA/TDMA/CDMA/OFDMA.
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increasin
To realize a better tradeoff between system throughput and user fairness a promising solution
is to break orthogonality.
NOMA serves more than one user on the same time and frequency resource.
Overview and Motivation
The next generation of wireless networks must support very high throughput, low latency, and massive connectivity. According to the
international telecommunication union (ITU),
5G networks must fulfill several requirements including:
(1) a minimum peak data rate of 10 Gbps (100 times more than that in the 3rd Generation Partnership Project (3GPP) Long-Term
Evolution (LTE))
(2) a latency of 1ms (ten times lower than that in 4G networks), and
(3) a connection density of 1,000,000 devices per km2 (100 times more than 4G networks)
NOMA can address the above challenges of the next generation of wireless networks more efficiently than the conventional orthogonal
multiple access schemes.
Overview and Motivation
Advantages
Disadvantages
OMA
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Simpler receiver detection
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Low spectral efficiency
Limited number of users
Unfairness for users
NOMA
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Higher spectral efficiency
Higher connection density
Enhanced user fairness
Lower latency
Supporting diverse QOS
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Increase complexity of
receivers
Basics of NOMA
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All the users are served at the same time frequency and code.
Exploits power domain multiplexing.
Users with better channel conditions get less power.
Successive Interference cancellation is used at the receivers.
Superposition coding at the transmitter side.
A pair of users can be served by NOMA if their channel gains are considerably different.
Power allocation strategies play a pivotal role in capacity enhancement
Comparison of NOMA with OFDMA
Comparison of OMA and NOMA
Superiority of NOMA over OMA
Spectral efficiency and throughput
User fairness, low latency, and massive connectivity
Compatibility
NOMA Schemes
NOMA schemes can be classified into two types:
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Power-domain multiplexing
Code-domain multiplexing.
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In power-domain multiplexing, different users are allocated different power coefficients according to their channel conditions
in order to achieve a high system performance. In particular, multiple users’ information signals are superimposed at the
transmitter side. At the receiver side successive interference cancellation (SIC) is applied for decoding the signals one by one
until the desired user’s signal is obtained, providing a good trade-of between the throughput of the system and the user
fairness.
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In code-domain multiplexing, different users are allocated different codes and multiplexed over the same time-frequency
resources, such as multi user shared access (MUSA), sparse code multiple access (SCMA), and low-density spreading
(LDS).
Uplink NOMA Network
Downlink NOMA Network
Basic NOMA
[1]
Cooperative NOMA
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Similar to the basic NOMA, cooperative NOMA also uses a SIC receiver for detecting the multi-user signal.
Therefore, the users associated with better channel conditions can be relied upon as relays in order to improve
the reception reliability of the users suffering from poor channel conditions.
For cooperative transmission, for example short-range communication techniques - such as Bluetooth and
ultra-wideband (UWB) schemes - can be used for delivering signals from the users benefitting from better
channel conditions to the users with poor channel conditions, which is the key difference with respect to the
basic NOMA associated with SIC.
NOMA in MIMO Systems
[1]
Advantages of NOMA
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NOMA offers higher spectral efficiency due to use of multiple users on same frequency resource.
It provides massive connectivity by serving more users simultaneously at the same time.
It provides lower latency due to simultaneous transmission all the time rather than dedicated
scheduled time slot.
It offers better QoS to all the users using flexible power control algorithms.
The NOMA along with MIMO delivers enhanced performance.
Disadvantages of NOMA
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Each of the users within the cluster need to decode information of all the other users even one having worst
channel gains. This leads to complexity in the receiver. Moreover energy consumption is higher.
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If error occurs in single user due to SIC, decoding of all the other users information will be erroneous. This
limits maximum number of users to be served by each of the clusters of the cell.
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In order to achieve desired functionalities of power domain concept in NOMA at the receiver, channel gain
difference between users should be adequate. This limits effective number of user pairs served by clusters.
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Each users required to provide channel gain informations back to Base Station as feedback and hence NOMA
is sensitive enough to obtain these measurements.
Applications of NOMA
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Visible Light Communication: Similar performance gains as seen in the RF case can be expected if NOMA is implemented in
VLC. As the channel generally does not change most of the time, the decoding becomes simpler.
MIMO-NOMA: The combination of MU-MIMO which allows multiple beams and NOMA within a single beam can lead to a
greater capacity of the system.
Internet of Things: The scenario in IoT is massive connectivity. Exploitation of Non-Orthogonal resources as a means to
enhance connectivity is subject to research.
SoDeMA: Software Defined Multiple Access is an active research area where the best multiple access scheme is chosen based
on the conditions of the system. For example, if we only have a small number of users and they do not have a large variance in
SNR, OMA would be preferrable to NOMA.
Active research areas
• Power Allocation
• Sum Rate maximization
• Optimal User Pairing
• Performance evaluation under various scenarios
• Energy Efficient resource allocation
REFERENCES
1.
2.
3.
4.
Linglong Dai, Bichai Wang, Yifei Yuan, Shuangfeng Han, Chih-Lin I, and Zhaocheng Wang, Non-Orthogonal Multiple Access
for 5G: Solutions, Challenges, Opportunities, and Future Research Trends,” IEEE Commun.Mag., vol. 53, no.9, pp. 74-81, Sep.
2015.
Mojtaba Vaezi, Zhiguo Ding, H. Vincent Poor, "Multiple Access Techniques for 5G Wireless Networks and Beyond", 2019,
ISBN: 978-3-319-92089-4.
L. Dai, B. Wang, Z. Ding, Z. Wang, S. Chen and L. Hanzo, "A Survey of Non-Orthogonal Multiple Access for 5G," in IEEE
Communications Surveys & Tutorials, vol. 20, no. 3, pp. 2294-2323, third quarter 2018, doi: 10.1109/COMST.2018.2835558
S. M. R. Islam, N. Avazov, O. A. Dobre and K. Kwak, "Power-Domain Non-Orthogonal Multiple Access (NOMA) in 5G
Systems: Potentials and Challenges," in IEEE Communications Surveys & Tutorials, vol. 19, no. 2, pp. 721-742, Secondquarter
2017, doi: 10.1109/COMST.2016.2621116