Transmission Strategies Of Swipt Based Integrated Satellite And Terrestrial Networks

With the rapid development of satellite communication technology and terrestrial wireless communication technology,the integrated satellite and terrestrial networks(ISTNs)architecture composed of satellite network and terrestrial network has shown great potential.However,the service life of ISTNs is constrained by the energy of nodes in the terrestrial network.Affected by geographical factors and its environment,once the energy constrained relay or destination node is unable to supplement energy,ISTNs will not be sustainable.Meanwhile,as one of the important enabling technologies,the simultaneous wireless information and power transfer(SWIPT)technology can meet the energy sustainability requirements of the terrestrial nodes in ISTNs.In order to achieve high frequency spectral efficiency,wide coverage and green communication,SWIPT technology can provide a new research idea in ISTNs.However,the composition of ISTNs based on SWIPT has certain uniqueness and complexity,and its related research is still initial.With the introduction of SWIPT technology,the effectiveness of the transmission schemes of the traditional ISTNs remains to be verified.Based on the above,this dissertation takes ISTNs architecture as the application background,explores and studies the feasible SWIPT transmission schemes in ISTNs with SWIPT,selective physical-layer network coding(SPNC),device-to-device(D2D)communication and other technologies to achieve the goals of high frequency spectral efficiency,wide coverage and sustainable communication respectively.The main research work includes the following:First,aiming at the energy limitation problem of internet of things(IoT)device in relay-assisted uplink ISTNs,the power-splitting(PS)and time-switching(TS)SWIPT transmission schemes in uplink ISTNs based on dispatch information time division return(TDR)are proposed respectively,and the TDR-PS/TS unified framework is established for the two transmission schemes.In the two proposed schemes,the terrestrial relay employs PS and TS technologies to provide energy for the IoT device to solve the problem that the IoT device cannot obtain energy sustainably.The IoT device utilizes the harvested energy to send its data to the relay,which employs the decode-and-forward(DF)protocol and forwards it to the satellite after decoding.In this paper,the closed-form expressions of outage probability,network throughput and energy efficiency of the two schemes are derived in the TDR-PS/TS framework.Theoretical analysis and simulation results show that IoT device can stably harvest energy from the terrestrial relay to ensure its outage performance at the satellite node,thus ensuring the reliability of the network in the proposed schemes.Secondly,aiming at the problem of coverage reduction caused by the masking effect in relay-assisted downlink ISTNs,the D2D-PS and D2D-TS SWIPT transmission schemes in downlink ISTNs are proposed respectively.In the two proposed schemes,in order to achieve the information transmission between the satellite and the masked IoT device when the IoT device affected by the masking effect is outside the coverage of the terrestrial relay,one user terminal,as the relay user equipment(RUE)in the D2 D communication architecture,provides cooperative services for the masked IoT device.Considering that the user terminal as RUE is energy constrained,in the two transmission schemes,RUE uses PS and TS technologies to harvest energy from the radio frequency(RF)signal of the terrestrial amplify-and-forward(AF)relay,and utilizes the harvested energy to forward the decoded information to the masked IoT device.In this paper,the closed-form expressions of outage probability,network throughput and energy efficiency of the two schemes are derived.Theoretical analysis and simulation results show that RUE can utilize the energy harvested from terrestrial relay to provide relay links for IoT device,thus improving its communication reliability and expanding the coverage of the network in the proposed schemes.Thirdly,to solve the problem that the channel asymmetry in the two-way relay ISTNs leads to the reduction of network throughput,the SPNC transmission scheme is proposed to maximize the end-to-end throughput between the satellite and the terrestrial IoT device firstly.DF relay calculates and compares the instantaneous throughput of one-way decoding detection scheme and two-way decoding detection scheme after receiving the superimposed signal.If the instantaneous throughput performance of one-way decoding is better than that of two-way decoding,the relay switches to the one-way decoding scheme,otherwise the two-way decoding scheme is maintained.The instantaneous BER,instantaneous end-to-end throughput,single node detection(SND)trigger probability,average end-to-end throughput and average BER are analyzed to verify the effectiveness of the scheme.Secondly,a two-way relay ISTNs transmission scheme based on PS and SPNC technology is proposed.The IoT device employs PS technology to harvest energy from the RF signal of the relay to solve the problem of energy limitation,and the instantaneous BER,instantaneous end-to-end throughput,average end-to-end throughput and energy efficiency are analyzed.Theoretical analysis and simulation results show that the proposed scheme can achieve higher spectral efficiency and energy efficiency compared with the traditional scheme.Fourthly,aiming at the energy limitation problem of primary network IoT device in the overlay downlink cognitive ISTNs,the PS SWIPT transmission scheme in downlink cognitive ISTNs is proposed.In the proposed scheme,the terrestrial relay employs the power allocation technology to send the signal carrying its own information and the signal from the satellite with different powers.The primary network IoT device employs the PS technology to harvest energy from the RF signal of the terrestrial relay to solve the problem of its own energy limitation.In this paper,the closed-form and asymptotic expressions for the outage probability of primary network IoT device and secondary network user terminal are derived,and the closed-form expressions for the throughput and energy efficiency of primary and secondary network are derived.Theoretical analysis and simulation results show that the proposed scheme can supplement energy for IoT device while ensuring the reliability of secondary network communication,thus improving the energy efficiency of the network.In addition,IoT device can also utilize relay link to improve its communication reliability.