Research On Cooperative Spectrum Sharing In Cognitive Radio Network And Non-Orthogonal Multiple Access Techniques

Mobile Internet has been widely deployed and some techniques such as artificial intelligence,machine learning,Internet of Things(IoT),and virtual/augmented re-ality gradually come to maturity.Those technological developments have driven the End-to-End communication demands of ultra-density and boundless wide-area cov-erage,high data rate and capacity,low-latency and high-reliability,low-power and massive-connections come into being.However,the traditional mobile telecommu-nication system can not satisfy the requirements of new techniques,new scenarios and new subscriptions,the advent of 5G era is coming.Among the wireless key techniques of 5G,SWIPT based spectrum sharing in cognitive radio network and non-orthogonal multiple access(NOMA)have now at-tracted intensive research interests from both academia and industry.Spectrum sharing is enable to realize the spectrum reuse and allows unlicensed users oppor-tunistically to access the license spectrum for its own data transmission.Combined with SWITP,the harmful interference becomes a source of energy,which can im-prove the energy efficiency and thus significantly prolong the network lifetime and meanwhile satisfy the needs of green communications.NOMA as a promising radio access technique has higher spectrum efficiency.The signals of multiple users are combined together using different powers and the superimposed signal is transmit-ted over the same channel.The flexible power allocation strategy will guarantee the system performance.In order to further improve the efficiencies of energy and spectrum and satisfy the requirements of 5G,in this paper,we mainly focus on the design of highly energy and spectral efficiency communication protocols in 5G scenario.Firstly,we propose a time-domain spectrum sharing scheme with energy cooperation from secondary system.Secondly,a time and space domain spectrum sharing scheme with the energy-data cooperation is proposed to further enhance the requirement of efficiency.We reveal the mutual impacts of system parameters on primary and secondary systems.Finally,we propose a NOMA relaying protocol with truncated ARQ and a cooperative relaying based NOMA scheme with the help of multiple relays.We analyze the system throughput and investigate the impacts of various system parameters.Our main contributions are listed as follows:1.For the cognitive radio network with one primary link and one secondary link,we propose a time-domain spectrum sharing scheme based on the wireless en-ergy transfer(WET).The secondary transmitter(ST)can wirelessly transfer energy along with the primary base station(PB)to the primary user equipment(UE).The UE can forward its primary data to the PB over the uplink using the harvested energy,while the ST is allowed to access the spectrum and transmit its own data for a time.The main idea is that the secondary system supplies energy to the primary system and acquires the spectrum for the secondary data transmission.Considering the dependence of the energy and data transfer,we analyze the throughput of both systems under the peak power constraint.The time allocations are determined by maximizing the throughput of secondary system while guaranteeing the throughput requirement of primary system.Simulation results are provided to validate our the-oretical analysis and the numerical results reveal the impacts of various parameter configurations to the system performance.2.We propose a spectrum sharing scheme based on the cooperative energy and data transfer in both the time and space domains.When the PB transfers energy to the primary UE,the secondary user(SU)can transmit its own data simultaneously,and the interference of secondary data transmission becomes beneficial to improve the EH efficiency of the PU.Furthermore,the SU can assist the primary data relaying using the Alamouti coding technique to improve the link robustness through introducing the space diversity.With the energy and data cooperation from the SU,the primary data can be more quickly and reliably delivered,and hence more opportunities can be achieved for the spectrum sharing.Considering the dependence of the energy and data transfer,the throughput of both systems is investigated.The time allocation between EH and data transmission can be numerically determined by maximizing the throughput of secondary system under the throughput constraint of primary system.Performance results are presented to validate our theoretical analysis and provide some guidelines for the network configuration.3.We propose a non-orthogonal multiple access relaying protocol with trun-cated automatic repeat request(ARQ),where the source simultaneously transmits two signals to the relay and the destination using superposition coding technique in the power domain.The successive interference cancelation technique is adopted by the relay,who should first decode its own data and then cancel it for the decoding of destination data.If either the data intended for the relay or the destination is erro?neously received by the relay,it will be retransmitted by the source using full power.After correctly decoding the source data intended for the destination,the relay will forward it and the retransmission is performed when the data is erroneously received by the destination.We derive the system throughput and investigate the impact-s of several parameters,such as power allocation factor,target rate,and distance between terminals etc.In terms of throughput,our proposed scheme can greatly outperform the conventional relaying scheme with truncated ARQ.4.We propose a cooperative relaying based NOMA scheme with the help of multiple relays.In the first phase,access point(AP)linearly combines the signals of near-user U1 and far-user U2 and then broadcasts the superimposed signal to U1 and multiple relays.U1 tries to decode its desired data by treating the signal of U2 as interference.In a cooperative zone between AP and U2,multiple relays try to decode the signal of U2 by decoding and canceling the signal of U1.In the second phase,the relay that can correctly decode the signal of U2 and has the best channel condition is selected to forward signal to U2.If U1 erroneously decodes its data in the first phase,it will listen the relayed signal of U2 and try to decode and cancel it for the further decoding of its own data.We analyze the system throughput and investigate the impacts of various system parameters.Numerical results show that our proposed scheme can greatly improve the system throughput with lower power consumption compared with the time division multiple access scheme.