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.
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
• 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.
|Full Form||Non-Orthogonal Multiple Access||Orthogonal Multiple Access|
|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.
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