You can have a look at
https://www.metis2020.com/wp-content/uploads/publications/VTC_2013_Saito_etal_NOMA.pdf
https://www.metis2020.com/wp-content/uploads/publications/ISPACS_2013_Benjebbour_etal_NOMAForFutureRA.pdf
This paper provides clear explanations of NOMA
https://www.metis2020.com/wp-content/uploads/publications/ISPACS_2013_Benjebbour_etal_NOMAForFutureRA.pdf
Hi Aamir,
NOMA, shorts for non orthogonal multiple access, is a new proposal for encoding technology.
In NOMA, several users can use the same frequency bandwidth whereas they are distinguished by the power value that allocated respectively. While decoding, say user k, the decoder will delect the signals of users with lower powers by SIC (successive interference cancellation),say, user 1 to (k-1). For the users with higher power, it will be treated as the noises.
What is the benefit while adopting in 5G? well, as users can share the same frequency bandwidth, the SE can greatly enhanced in such a scheme, while 5G is calling for even higher transmission rate.
Cheers!
Di
The key idea of NOMA is to use the power domain for multiple access, whereas the previous generations of mobile networks have been relying on the time/frequency/code domain. Take the conventional orthogonal frequency-division multiple access (OFDMA) used by 3GPP-LTE as an example. A main issue with this orthogonal multiple access (OMA) technique is that its spectral efficiency is low when some bandwidth resources, such as subcarrier channels, are allocated to users with poor channel state information (CSI). On the other hand, the use of NOMA enables each user to have access to all the subcarrier channels, and hence the bandwidth resources allocated to the users with poor CSI can still be accessed by the users with strong CSI, which significantly improves the spectral efficiency.
For the detail explanation, please refer to the magazine paper below：
Application of Non-orthogonal Multiple Access in LTE and 5G Networks
http://arxiv.org/abs/1511.08610
Best Regards,
Yuanwei
Dear Aamir Habib
Different from conventional orthogonal multiple access technologies, NOMA can accommodate much more users via non-orthogonal resource allocation. We divide existing dominant NOMA schemes into two categories: power-domain multiplexing and code-domain multiplexing, and the corresponding schemes include power-domain NOMA, multiple access with low-density spreading, sparse code multiple access, multi-user shared access, pattern division multiple access, and so
on.
There are various types of NOMA techniques, for example, power-domain NOMA and code-domain NOMA. Power-domain NOMA attains multiplexing in power domain and code-domain NOMA achieves multiplexing in code domain. One way of implementing power-domain NOMA is utilizing superposition coding (SC) at the transmitter and successive interference cancellation (SIC) at the receiver. SC allows the transmitter to transmit multiple users’ information at the same time. To decode the superposed information at each receiver, SIC technique can be used. The main idea of SIC is that user signals are successively decoded. After one user’s signal is decoded, it is subtracted from the combined signal before the next user’s signal is decoded.
Someone interested is referred to the paper:
http://arxiv.org/abs/1609.06261
Any reference on code-domain NOMA? Meanwhile, if using code-domain multiplexing, what is the difference between the NOMA and conventional CDMA? Thank you!
Sir Leen Lool below listed some current topics regarding NOMA
Cooperative NOMA, New modulation schemes for NOMA, Massive MIMO NOMA, Cognitive radio interplay with NOMA, Error propagation in NOMA, Power allocation issues in NOMA
The key to NOMA, non-orthogonal multiple access is to have signals that possess significant differences in power levels. It is then possible to totally isolate the high level signal at the receiver and then cancel it out to leave only the low level signal. In this way, NOMA exploits the path loss differences amongst users, although it does need additional processing power in the receiver.
Looking at NOMA in a little more detail, non-orthogonality is intentionally introduced either in time, frequency or code.Then as the signal is received demultiplexing is obtained as a result of the large power difference between the two users. To extract the signal, successive interference cancellation is used within the receiver. The channel gain consisting of elements including the path-loss and received signal to noise ratio difference between users is translated into multiplexing gains. Although power sharing reduces the power allocated to each user, both users - those with high channel gains and those with low channel gains benefit by being scheduled more frequently and by being assigned more bandwidth. This means that NOMA enables system capacity and fairness of allocations to be improved for all users.
In addition to this NOMA, non-orthogonal multiple access is able to support more connections than other systems and this will become particularly useful in view of the massive projected increase in connectivity for 5G
- NOMA is a combination of OFDMA with superposition and interference cancellation techniques.
- Multiple users are multiplexed in the power-domain on Tx side and multi-user signal separation on Rx is performed based on Successive Interference Cancellation (SIC)
I read the answers above and I found some of them very helpful and I also found this tutorial that I recommend you to read it
Article https://www.hindawi.com/journals/wcmc/2018/9713450/
As well as, this code may help to start the simulation of NOMA https://www.mathworks.com/matlabcentral/answers/329970-i-am-struggling-with-a-code-the-code-for-signal-transmition-in-non-orthogonal-multiple-access-pleas#answer_288771
https://github.com/roamiri/RA-NOMA
https://github.com/yagneshmb/Suboptimal_NOMA_5G?files=1
https://github.com/search?q=Non+Orthogonal+Multiple+Access
For Power-domain non orthogonal multiple access, Kindly go through:
https://link.springer.com/article/10.1007/s11276-018-1807-z#:~:text=Non%2Dorthogonal%20multiple%20access%20(NOMA,scheme%20for%20future%205G%20networks.&text=Power%20domain%2DNOMA%20(PD%2D,utilization%20for%20downlink%20cooperative%20networks.
This paper provides clear explanations of Non Orthogonal Multiple Access
Article A Tutorial on Nonorthogonal Multiple Access for 5G and Beyond
In NOMA, you can transmit multiple signals carried on the same frequency at the same time in the same spot area. Different power is allocated to each user in the cell, so you can see it as power modulation technology. Special receivers should be used to separate the multiplexed signals in the NOMA system.
the benefit of NOMA is increasing the capacity and the overall throughput. On the other hand, you should process the high interference problem.
The primary reason for adopting NOMA in 5G owes to its ability of serving multiple users using the same time and frequency resources.
