Outage performance of decode-and-forward (DF)-based multiuser spectrum sharing relay system with direct link in the presence of primary users’ power

2018 ◽  
Vol 12 (3) ◽  
pp. 246-254 ◽  
Author(s):  
Omid Moghimi Kandelusy ◽  
Seyed Mehdi Hosseini Andargoli
Keyword(s):  
Spectrum Sharing ◽  
Direct Link ◽  
Decode And Forward ◽  
Relay System ◽  
Outage Performance ◽  
Primary Users

On the Outage Performance of Decode-and-Forward Opportunistic Mobile Relaying with Direct Link

2016 ◽  
Vol E99.B (3) ◽  
pp. 654-665 ◽  
Author(s):  
Hui TIAN ◽  
Kui XU ◽  
Youyun XU ◽  
Xiaochen XIA
Keyword(s):  
Direct Link ◽  
Decode And Forward ◽  
Outage Performance

scholarly journals Multiple Access-Enabled Relaying with Piece-Wise and Forward NOMA: Rate Optimization under Reliability Constraints

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4783
Author(s):  
Farnaz Khodakhah ◽  
Aamir Mahmood ◽  
Patrik Österberg ◽  
Mikael Gidlund
Keyword(s):  
Spectrum Sharing ◽  
Multiple Access ◽  
Cooperative Relaying ◽  
Achievable Rate ◽  
Second Phase ◽  
Relay Channel ◽  
Direct Link ◽  
Secondary System ◽  
Amplify And Forward ◽  
Decode And Forward

The increasing proliferation of Internet-of-things (IoT) networks in a given space requires exploring various communication solutions (e.g., cooperative relaying, non-orthogonal multiple access, spectrum sharing) jointly to increase the performance of coexisting IoT systems. However, the design complexity of such a system increases, especially under the constraints of performance targets. In this respect, this paper studies multiple-access enabled relaying by a lower-priority secondary system, which cooperatively relays the incoming information to the primary users and simultaneously transmits its own data. We consider that the direct link between the primary transmitter–receiver pair uses orthogonal multiple access in the first phase. In the second phase, a secondary transmitter adopts a relaying strategy to support the direct link while it uses non-orthogonal multiple access (NOMA) to serve the secondary receiver. As a relaying scheme, we propose a piece-wise and forward (PF) relay protocol, which, depending on the absolute value of the received primary signal, acts similar to decode-and-forward (DF) and amplify-and-forward (AF) schemes in high and low signal-to-noise ratio (SNR), respectively. By doing so, PF achieves the best of these two relaying protocols using the adaptive threshold according to the transmitter-relay channel condition. Under PF-NOMA, first, we find the achievable rate region for primary and secondary receivers, and then we formulate an optimization problem to derive the optimal PF-NOMA time and power fraction that maximize the secondary rate subject to reliability constraints on both the primary and the secondary links. Our simulation results and analysis show that the PF-NOMA outperforms DF-NOMA and AF-NOMA-based relaying techniques in terms of achievable rate regions and rate-guaranteed relay locations.

scholarly journals Performance Analysis of Cooperative NOMA Networks with Imperfect CSI over Nakagami-m Fading Channels

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 424 ◽  
Author(s):  
Xianli Gong ◽  
Xinwei Yue ◽  
Feng Liu
Keyword(s):  
Outage Probability ◽  
Fading Channels ◽  
Multiple Access ◽  
Base Station ◽  
High Signal ◽  
Direct Link ◽  
Decode And Forward ◽  
Estimation Errors ◽  
Channel Estimation Errors ◽  
Outage Performance

In this paper, we investigate a downlink cooperative non-orthogonal multiple access (NOMA) network with decode-and-forward relaying, where two scenarios of user relaying with direct link and user relaying without direct link are discussed in detail. More particularly, the performance of cooperative NOMA system under the assumption of imperfect channel state information (ipCSI) is studied over Nakagami-m fading channels. To evaluate the outage performance of the above discussed two scenarios, the closed-form expressions of outage probability for a pair of users are derived carefully. The diversity orders of users are achieved in the high signal-to-noise region. An error floor appears in the outage probability owing to the existence of channel estimation errors under ipCSI conditions. Simulation results verify the validity of our analysis and show that: (1) NOMA is superior to conventional orthogonal multiple access; (2) The best user relaying location for cooperative NOMA networks should be near to the base station; and (3) The outage performance of distant user with direct link significantly outperforms distant user without direct link by comparing the two scenarios.

scholarly journals Outage Probability of Cognitive DF Relay Systems over Nakagami-m Fading

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
Dong Qin
Keyword(s):  
Outage Probability ◽  
Data Transmission ◽  
Spectrum Sharing ◽  
Peak Power ◽  
Primary System ◽  
Secondary System ◽  
Decode And Forward ◽  
Relay System ◽  
Relay Systems ◽  
The Impact

This paper aims to derive accurate outage probability expressions of a cognitive decode-and-forward (DF) relay system over the Nakagami-m fading channel. A secondary system and a primary system coexist in a spectrum sharing the environment. In order to protect the data transmission of the primary system, the transmission power of the secondary system cannot exceed the tolerable interference threshold of the primary system and its available peak power. In particular, we also consider the impact on the secondary system when the primary system turns on its transmitter. Simulation results align with our theoretical formulas very well.

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