scholarly journals Optimal Multi-Antenna Transmission for the Cooperative Non-Orthogonal Multiple-Access System

2021 ◽  
Vol 11 (5) ◽  
pp. 2203
Author(s):  
Duckdong Hwang ◽  
Janghoon Yang ◽  
Sung Sik Nam ◽  
Hyoung-Kyu Song
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Average Power ◽  
Access Point ◽  
Power Performance ◽  
Multiple User ◽  
Structure Simulation ◽  
Rank One ◽  
Multiple Access System ◽  
Optimal Beamforming

We investigate the beamforming for the multi antenna cooperative non-orthogonal multiple access (NOMA) system, where an access point (AP) delivers messages for multiple user terminals (UT) with successive interference cancellation (SIC) reception method. Some UTs with multiple antennas cooperate with the AP transmission to improve the diversity and the average power performance. We formally present two optimal beamforming schemes at the AP and at the cooperative UTs. One scheme has no power limitation for the cooperative UTs, while the other one does have such limitation. We guarantee that the rank one beamformer is sufficient to achieve the optimal points so that the proposed schemes have rank one semi-definite programming (SDP) structure. Simulation results show the performance gain of the multi-antenna cooperative NOMA schemes in the sense of diversity and the average power.

Peak Average Power Reduction in NOMA by using PTSCT Technique

2020 ◽  
Vol 13 (3) ◽  
pp. 502-507 ◽  
Author(s):  
Arun Kumar ◽  
Manisha Gupta
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Multiple Access ◽  
Average Power ◽  
High Peak Power ◽  
Power Ratio ◽  
Transmission Scheme ◽  
Multiple Access Schemes ◽  
Power Ratio Reduction ◽  
Multiple Access System ◽  
Ratio Reduction

Background: High peak power is one of the several disadvantages which need to be addressed for its effective regularization. It hampers the performance of the system due to the utilization of the orthogonal frequency division multiplexing transmission scheme at the sender of the Non-orthogonal multiple access system. Objective: In this work, a new Partial transmission sequence circular transformation reduction technique is designed for Non-orthogonal multiple access schemes. Methods: Partial transmission sequence is considered to be one of the most efficient techniques to reduce the Peak to average power ratio but it leads to high computational complexity. Additionally, a circular transformation is implemented. In the proposed technique, circular transformation and alternate optimization are used. Results: Simulation results reveal that the Peak to average power ratio performance of the proposed technique is better as compared to the conventional partial transmission sequence. Conclusion: It is observed that the proposed technique achieved 80% Peak to average power ratio reduction and 90 % bit error rate performance as compared to the conventional Partial transmission sequence.

Performance of Different OCDMA Codes with FWM and XPM Nonlinear Effects

2017 ◽  
Vol 38 (3) ◽  
Author(s):  
Shivani Rana ◽  
Amit Gupta
Keyword(s):  
Phase Modulation ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Cross Correlation ◽  
Nonlinear Effects ◽  
Access System ◽  
Multiple User ◽  
Code Division Multiple ◽  
User Interference ◽  
Multiple Access System

AbstractIn this paper, 1 Gb/s non-linear optical code division multiple access system have been simulated and modeled. To reduce multiple user interference multi-diagonal (MD) code which possesses the property of having zero cross-correlation have been deployed. The MD code shows better results than Walsh-Hadamard and multi-weight code under the nonlinear effect of four-wave mixing (FWM) and cross-phase modulation (XPM). The simulation results reveal that effect of FWM reduces when MD codes are employed as compared to other codes.

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