The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) com...The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) communication systems. We consider an uplink NOMA scenario for such a satellite-aerial-ground integrated network where multiple users communicate with satellite under the help of an Unmanned Aerial Vehicle(UAV) as an aerial relay equipped with a phased array. Supposing that buffer-aided decode-and-forward protocol is adopted at the UAV relay, we first formulate an optimization problem to maximize Ergodic Sum Rate(ESR) of the considered system subject to individual power constraint and quality-of-service constraint of each user.Then, with known imperfect channel state information of each user, we propose a joint power allocation and robust Beam Forming(BF) iterative algorithm to maximize ESR for the user-to-UAV link. Besides, to take the advantages of Free-Space Optical(FSO) and millimeter Wave(mmWave)communications, we present a switch-based hybrid FSO/mmWave scheme and a robust BF algorithm for the UAV-to-satellite link to achieve higher rate. Moreover, a closed-form ESR expression is derived. Finally, the effectiveness and correctness of the proposed solutions are verified by numerical simulations, and the performance evaluation results show that the proposed solutions not only achieve performance enhancement and robustness, but also outperform the orthogonal multiple access significantly.展开更多
A multi-objective optimization based robust beamforming(BF)scheme is proposed to realize secure transmission in a cognitive satellite and unmanned aerial vehicle(UAV)network.Since the satellite network coexists with t...A multi-objective optimization based robust beamforming(BF)scheme is proposed to realize secure transmission in a cognitive satellite and unmanned aerial vehicle(UAV)network.Since the satellite network coexists with the UAV network,we first consider both achievable secrecy rate maximization and total transmit power minimization,and formulate a multi-objective optimization problem(MOOP)using the weighted Tchebycheff approach.Then,by supposing that only imperfect channel state information based on the angular information is available,we propose a method combining angular discretization with Taylor approximation to transform the non-convex objective function and constraints to the convex ones.Next,we adopt semi-definite programming together with randomization technology to solve the original MOOP and obtain the BF weight vector.Finally,simulation results illustrate that the Pareto optimal trade-off can be achieved,and the superiority of our proposed scheme is confirmed by comparing with the existing BF schemes.展开更多
针对多波束卫星通信系统下行链路存在多个窃听者的场景,在仅已知窃听者大概位置的条件下,提出了两种鲁棒安全波束成形(beamforming,BF)方案。一种是基于卫星总发射功率受限条件下的系统安全速率最大化准则,提出了基于广义瑞利商的鲁棒B...针对多波束卫星通信系统下行链路存在多个窃听者的场景,在仅已知窃听者大概位置的条件下,提出了两种鲁棒安全波束成形(beamforming,BF)方案。一种是基于卫星总发射功率受限条件下的系统安全速率最大化准则,提出了基于广义瑞利商的鲁棒BF方案,得到了BF权矢量的解析解。另一种是基于安全速率和卫星总发射功率约束下的安全能效最大化准则,提出了一种分式规划、罚函数以及凸差(difference of convex,DC)规划理论相结合的嵌套迭代算法,完成鲁棒BF设计。仿真结果表明,跟传统的非鲁棒BF方案相比,所提出的两种鲁棒BF方案能够获得更好的安全性能。展开更多
基金co-supported by the Key International Cooperation Research Project,China(No.61720106003)Jiangsu Province Science and Technology Project,China(No.BE2021031)+4 种基金the Shanghai Aerospace Science and Technology Innovation Foundation,China(No.SAST2019-095)NUPTSF(No.NY220111)the Research Project of Science and Technology on Complex Electronic System Simulation Laboratory,China(No.DXZT-JC-ZZ-2019-009)the National Natural Science Foundation of China(No.61801234)the Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(No.KYCX210739)。
文摘The application of Non-Orthogonal Multiple Access(NOMA) technology into satelliteaerial-ground integrated networks can meet the requirements of ultra-high rate and massive connectivity for the Sixth-Generation(6G) communication systems. We consider an uplink NOMA scenario for such a satellite-aerial-ground integrated network where multiple users communicate with satellite under the help of an Unmanned Aerial Vehicle(UAV) as an aerial relay equipped with a phased array. Supposing that buffer-aided decode-and-forward protocol is adopted at the UAV relay, we first formulate an optimization problem to maximize Ergodic Sum Rate(ESR) of the considered system subject to individual power constraint and quality-of-service constraint of each user.Then, with known imperfect channel state information of each user, we propose a joint power allocation and robust Beam Forming(BF) iterative algorithm to maximize ESR for the user-to-UAV link. Besides, to take the advantages of Free-Space Optical(FSO) and millimeter Wave(mmWave)communications, we present a switch-based hybrid FSO/mmWave scheme and a robust BF algorithm for the UAV-to-satellite link to achieve higher rate. Moreover, a closed-form ESR expression is derived. Finally, the effectiveness and correctness of the proposed solutions are verified by numerical simulations, and the performance evaluation results show that the proposed solutions not only achieve performance enhancement and robustness, but also outperform the orthogonal multiple access significantly.
基金supported by the Key International Cooperation Research Project(61720106003)the National Natural Science Foundation of China(62001517)+2 种基金the Shanghai Aerospace Science and Technology Innovation Foundation(SAST2019-095)the NUPTSF(NY220111)the Foundational Research Project of Complex Electronic System Simulation Laboratory(DXZT-JC-ZZ-2019-009,DXZTJC-ZZ-2019-005).
文摘A multi-objective optimization based robust beamforming(BF)scheme is proposed to realize secure transmission in a cognitive satellite and unmanned aerial vehicle(UAV)network.Since the satellite network coexists with the UAV network,we first consider both achievable secrecy rate maximization and total transmit power minimization,and formulate a multi-objective optimization problem(MOOP)using the weighted Tchebycheff approach.Then,by supposing that only imperfect channel state information based on the angular information is available,we propose a method combining angular discretization with Taylor approximation to transform the non-convex objective function and constraints to the convex ones.Next,we adopt semi-definite programming together with randomization technology to solve the original MOOP and obtain the BF weight vector.Finally,simulation results illustrate that the Pareto optimal trade-off can be achieved,and the superiority of our proposed scheme is confirmed by comparing with the existing BF schemes.
文摘针对多波束卫星通信系统下行链路存在多个窃听者的场景,在仅已知窃听者大概位置的条件下,提出了两种鲁棒安全波束成形(beamforming,BF)方案。一种是基于卫星总发射功率受限条件下的系统安全速率最大化准则,提出了基于广义瑞利商的鲁棒BF方案,得到了BF权矢量的解析解。另一种是基于安全速率和卫星总发射功率约束下的安全能效最大化准则,提出了一种分式规划、罚函数以及凸差(difference of convex,DC)规划理论相结合的嵌套迭代算法,完成鲁棒BF设计。仿真结果表明,跟传统的非鲁棒BF方案相比,所提出的两种鲁棒BF方案能够获得更好的安全性能。
