NOMA vs OMA | Difference between NOMA and OMA | 5G

This page compares NOMA vs OMA and mentions difference between NOMA and OMA used in 5G Wireless technology. NOMA stands for Non-Orthogonal Multiple Access and OMA stands for conventional Orthogonal Multiple Access.

Both NOMA and OMA are multiple access techniques which utilize power domain/code domain and time/frequency domain respectively. The TDMA and OFDMA are examples of OMA techniques.

NOMA | Non-Orthogonal Multiple Access

The NOMA is a multiple access technique employed in 5G cellular wireless network. The main function of NOMA is to serve multiple UEs (User Equipments) using single 5G-NB (Node B or Base Station). It serves multiple users on same time/frequency resources.

There are two main techniques employed in NOMA for multiple access.
• Power domain: Here NOMA achieves multiplexing based on different power levels.
• Code domain: Here NOMA achieves multiplexing based on different codes.

NOMA, Non-Orthogonal Multiple Access

Transmit side: NOMA uses superposition coding at the transmitter end. The different power levels have been assigned to users. As shown in the figure-1, Base Station transmits superposed signals to User#1 and User#2. Here User#2 uses high gain and User#1 uses low gain as shown.

Receive side: NOMA uses SIC (Successive interference cancellation) technique to retrieve data of both the users. At receiver, User#2 (Strong User) substracts signal of user#1 through SIC and later decodes its own signal. User#1 (Weak User) treats signal of User#2 as noise and decodes its own signal directly.

OMA | Orthogonal Multiple Access

OMA, Orthogonal Multiple Access

• In OMA, frequency domain is shared among users. As shown U1 part of frequency spectrum is allocated to User#1 and U2 part is allocated to User#2.
• Refer advantages and disadvantages of NOMA over OMA >> technique.
• Example: TDMA, OFDMA
• Refer OFDM Vs OFDMA >> and SC-FDMA Vs OFDMA >>

Following table summarizes difference between NOMA and OMA.

Specifications NOMA OMA
Full Form Non-Orthogonal Multiple Access Orthogonal Multiple Access
Receiver complexity High Low
Energy consumption More Less
Number of users/cluster Lower Higher
Number of user pairs Less More
System throughput (Assumption: User fairness is guaranteed) Larger Smaller

Also refer difference between NOMA and OFDMA for more information.


This 5G tutorial also covers following sub topics on the 5G technology:
5G tutorial
Difference between 4G and 5G
5G testing and test equipments
5G network architecture

Difference between OFDM, FBMC, OFDMA and FDM

Following links provide difference between OFDM and FBMC as well as difference between OFDM vs OFDMA and difference between OFDM vs FDM.
OFDM Frame Structure and comparison with OFDMA
Basics of OFDM and difference between FDM and OFDM

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Difference between SC-FDMA and OFDM
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RF and Wireless Terminologies