Optimal power allocation for CRN-NOMA systems with adaptive transmit power
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ORIGINAL PAPER
Optimal power allocation for CRN-NOMA systems with adaptive transmit power Raed Alhamad1
· Hatem Boujemâa2
Received: 15 September 2019 / Revised: 5 January 2020 / Accepted: 12 March 2020 © Springer-Verlag London Ltd., part of Springer Nature 2020
Abstract In this paper, we derive the throughput of non-orthogonal multiple access NOMA with adaptive transmit power for cognitive radio networks (CRN). The secondary source and relay adapt their power to not generate high interference at primary destination. We evaluate the packet error probability and the throughput at the packet level, while previous studies compute it at the symbol level. We also optimize the powers allocated to near and far users to maximize the throughput of CRN-NOMA. Besides, optimal power allocation of CRN-NOMA with adaptive transmit power has not been yet suggested and previous studies deal with fixed transmit power. Keywords NOMA · CRN · Throughput optimization
1 Introduction In orthogonal multiple access (OMA), signals of different users are transmitted over different channels such as time slots or frequency bands [1]. To improve data rates, the use of non-orthogonal multiple access (NOMA) has been recently suggested [1–3]. In NOMA systems, transmission to different users is performed over the same channel and interference cancelation techniques are mandatory [4]. Transmission to far user is performed with a higher power allocation coefficient than near user. Near user detects the signal of far user and removes it since it is received with a high amplitude. Then, near user detects its own symbol. Far user detects only its symbol and treats the signal of near user as noise [1–4].
2 Literature review Relaying techniques for NOMA systems have been considered in [5–7]. Dual hop relaying has been studied in [5] where
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Raed Alhamad [email protected] Hatem Boujemâa [email protected]
1
2
Department of Computer Science, Saudi Electronic University, Riyadh, Saudi Arabia COSIM Lab, Tunis, Tunisia
the signal is transmitted from the source to relay then to far and near users. Multihop relaying for NOMA has been studied in [6,7] to extend the coverage. The signal goes from source to consecutive relays before reaching near and far users [6,7]. NOMA with energy harvesting has been suggested in [8–11]. Relay and source can harvest energy from different sources of energy such as solar wind or radio frequency (RF) signals. NOMA for cognitive radio networks (CRN) has been studied in [12–16]. In CRN, secondary nodes and primary nodes transmit over the same channel. Secondary nodes can transmit when primary users are idle known as interweave CRN. In underlay CRN, secondary nodes adapt their power to not cause harmful interference at primary destination. In overlay CRN, secondary nodes relay signals dedicated to primary nodes to improve their (signal to interference plus noise ratio) SINR. Optimal power allocation for NOMA systems has been investigated in [17]. A non-cognitive radio network has been considered in [17]. It has been
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