NOMA (Non-Orthogonal Multiple Access) is a multiple access technique that allows all users to be served on the same time/frequency resources. It uses superposition coding at the transmitter and successive interference cancellation at the receiver. Users with better channel conditions receive less power, while users with poorer channels receive more power. Cooperation in NOMA can improve performance, such as one user acting as a relay for another, or using dedicated relays to help cell edge users. Future work on NOMA includes combining it with massive MIMO, cognitive radio, random access networks, and optimizing metrics like user fairness.

1. Presentation Topic :
NOMA
Presented By:
Minhaz Uddin
ID :

2. What is NOMA ?
NOMA stand for Non-
Orthogonal Multiple Access
In NOMA :
•All the users are served at the
same time, frequency and code
•Users with better channel
conditions get less power
•Successive interference
cancellation is used at the
receivers

3. NOMA exploits superposition coding at the
transmitter and successive interference cancellation
(SIC) at the receiver, thus multiplexing users in the
power domain. As shown in Fig. 1, the base station
(BS) sends the superposed signals to two users,
where User 1 has higher channel gain than User 2. In
NOMA, the user with higher channel gain and the user
with lower channel gain are usually referred to as the
strong user and the weak user, respectively. The
strong user first subtracts the signal of the weak user
through SIC, and then decodes its own signal; the
weak user considers the signal of the strong user as
noise and detects its own signal directly. With worse
channel gain and more interference, the weak user is
assigned more power in NOMA to ensure fairness.

5. The principle of cooperative
NOMA and types of
Cooperation :
There are basically two types of
Cooperation :
# Cooperation among NOMA
user
#Employing dedicated relays

6. Cooperation among NOMA user :
One NOMA user acts as a relay for the
other one. There is redundant
information in NOMA system, which can
be employed for cooperative
transmission. The two user downlink
case is such type of situation.
There is a need for carrying out
cooperative transmission in NOMA
system.
Cooperative transmission can improves
the weak user data rate.

7. Employing dedicated relays :
First motivation for this form of NOMA is
to spectrally efficiently reach user close
to the cell edge.
Consider a dedicated delay which is
used to help for two user. when
Cooperative OMA is used we need four
time slot on the other hand in case of
NOMA we need two time slot for
transmission.

8. Second motivation is that there can be a
large number of idle users in wireless
network in network deployed in sport
stadiums and convention centers.
These users can be used as a
dedicated relays to help other users and
to improve system coverage.

9. Future Of NOMA:
# We use it in hybrid
multiple access
# We try to combine massive MIMO with
NOMA
#Interplay between NOMA and cognitive
radio
#Trying to use NOMA in ALOHA based
random access network, vehicular ad-
hoc network

10. #Theoretical analysis of achievable
rate and overloading
#Security provisioning in NOMA
#Cross layer optimization
#Trying to evaluate different metrics
that aim at maximizing the user
fairness instead of the achieved total
throughput.
#Design of spreading sequences or
codebooks