针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统在进行自适应比特功率分配时存在过高复杂度的问题,提出了一种基于边缘自适应(margin adaptive,MA)准则的改进低复杂度自适应比特功率分配算法。与贪婪(Greedy)...针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统在进行自适应比特功率分配时存在过高复杂度的问题,提出了一种基于边缘自适应(margin adaptive,MA)准则的改进低复杂度自适应比特功率分配算法。与贪婪(Greedy)算法相比,提出的改进算法通过预分配和迭代分配2部分来降低算法的计算量。改进算法先在预分配中根据信道条件预先分配部分比特,在迭代分配中通过增大内存开销的方法减少Greedy算法中计算和比较每个子信道功率增量的次数,从而降低算法的复杂度。仿真结果表明,在相同的仿真环境下算法的自适应分配效果和Greedy算法的自适应分配效果基本一致,同时该算法和Greedy算法具有几乎相同的误比特性能。且随着子信道数量的增加,与Greedy算法相比,该算法的运行时间更短,进而说明所提出的算法具有较低的复杂度。展开更多
In this paper,a cellular-connected unmanned aerial vehicle(UAV)mobile edge computing system is studied where several UAVs are associated to a terrestrial base station(TBS)for computation offloading.To compute the larg...In this paper,a cellular-connected unmanned aerial vehicle(UAV)mobile edge computing system is studied where several UAVs are associated to a terrestrial base station(TBS)for computation offloading.To compute the large amount of data bits,a part of computation task is migrated to TBS and the other part is locally handled at UAVs.Our goal is to minimize the total energy consumption of all UAVs by jointly adjusting the bit allocation,power allocation,resource partitioning as well as UAV trajectory under TBS’s energy budget.For deeply comprehending the impact of multi-UAV access strategy on the system performance,four access schemes in the uplink transmission is considered,i.e.,time division multiple access,orthogonal frequency division multiple access,one-by-one access and non-orthogonal multiple access.The involved problems under different access schemes are all formulated in non-convex forms,which are difficult to be tackled optimally.To solve this class of problem,the successive convex approximation technique is employed to obtain the suboptimal solutions.The numerical results show that the proposed scheme save significant energy consumption compared with the benchmark schemes.展开更多
针对经典贪婪算法(greedy)迭代次数多、运算量大的缺点,提出一种基于边缘自适应(margin adaptive,MA)准则的改进贪婪算法来进行正交频分复用(orthogonal frequency division multiplexing,OFDM)系统的自适应比特功率分配。与贪婪算法相...针对经典贪婪算法(greedy)迭代次数多、运算量大的缺点,提出一种基于边缘自适应(margin adaptive,MA)准则的改进贪婪算法来进行正交频分复用(orthogonal frequency division multiplexing,OFDM)系统的自适应比特功率分配。与贪婪算法相比,改进算法通过预分配和迭代分配两部分来降低算法的计算量。在预分配中改进算法通过引入功率利用率函数,对信道条件好的子信道预先加载一部分比特。然后,在迭代分配的过程中,引用分类排序的思想,用一张表格存储子信道的功率变化情况,从而降低算法的复杂度。仿真结果表明,在相同的仿真环境下,改进算法和Greedy算法的误比特性能几乎一致,但改进算法的运行时间更短。展开更多
Cognitive radio （CR） is a promising technology deemed to improve the efficiency of spectrum utilization. This paper considers a spectrum underlay cognitive radio network, in which the cognitive users （CUs） are all...Cognitive radio （CR） is a promising technology deemed to improve the efficiency of spectrum utilization. This paper considers a spectrum underlay cognitive radio network, in which the cognitive users （CUs） are allowed to use the radio spectrum concurrently with the primary users （PUs） under the interference temperature constraint. We investigate the system performance by using the proposed joint channel and power allocation scheme under two transmit strategies to achieve higher data rates and performance diversity gain respectively. Simulation results show that the proposed scheme provides a significant improvement on the bit error rate （BER） performance and spectrum efficiency of a cognitive wireless network.展开更多
A novel adaptive power loading algorithm with the constraint of target overall bit error rate （BER） for orthogonal frequency division multiplexing （OFDM） systems is proposed in this article. The proposed algorithm...A novel adaptive power loading algorithm with the constraint of target overall bit error rate （BER） for orthogonal frequency division multiplexing （OFDM） systems is proposed in this article. The proposed algorithm aims to minimize the required transmit power with fixed data rate and uniform （nonadaptive） bit allocation, while guaranteeing the target overall BER. The power loading is based on the unequal-BER （UBER） strategy that allows unequal mean BERs on different subcarriers. The closed-form expressions for optimal BER and power distributions are derived in this article. Simulation results indicate the superiority of the proposed algorithm in terms of BER performance and algorithmic complexity.展开更多
文摘针对正交频分复用(orthogonal frequency division multiplexing,OFDM)系统在进行自适应比特功率分配时存在过高复杂度的问题,提出了一种基于边缘自适应(margin adaptive,MA)准则的改进低复杂度自适应比特功率分配算法。与贪婪(Greedy)算法相比,提出的改进算法通过预分配和迭代分配2部分来降低算法的计算量。改进算法先在预分配中根据信道条件预先分配部分比特,在迭代分配中通过增大内存开销的方法减少Greedy算法中计算和比较每个子信道功率增量的次数,从而降低算法的复杂度。仿真结果表明,在相同的仿真环境下算法的自适应分配效果和Greedy算法的自适应分配效果基本一致,同时该算法和Greedy算法具有几乎相同的误比特性能。且随着子信道数量的增加,与Greedy算法相比,该算法的运行时间更短,进而说明所提出的算法具有较低的复杂度。
基金National High Technology Project of China under Grant 2015AA01A703Scientific and Technological Key Project of Henan Province under Grant 182102210449+6 种基金China Postdoctoral Science Foundation under Grant 2018M633733the Scientific Key Research Project of Henan Province for Colleges and Universities under Grand 19A510024the Scientific Research Foundation of Graduate School of Southeast University under Grand YBPY1859the National Science and Technology Major Project of China under Grant 2018ZX03001002-003the Research Project of Jiangsu Province under Grant BE2018121the Natural Science Foundation of the Jiangsu Higher Education Institutions of China under Grant 18KJB510026,and by the Foundation of Nanjing University of Posts and Telecommunications under Grant NY218124the National Natural Science Foundation of China under Grants 61801243,61801435,61372101,61720106003.
文摘In this paper,a cellular-connected unmanned aerial vehicle(UAV)mobile edge computing system is studied where several UAVs are associated to a terrestrial base station(TBS)for computation offloading.To compute the large amount of data bits,a part of computation task is migrated to TBS and the other part is locally handled at UAVs.Our goal is to minimize the total energy consumption of all UAVs by jointly adjusting the bit allocation,power allocation,resource partitioning as well as UAV trajectory under TBS’s energy budget.For deeply comprehending the impact of multi-UAV access strategy on the system performance,four access schemes in the uplink transmission is considered,i.e.,time division multiple access,orthogonal frequency division multiple access,one-by-one access and non-orthogonal multiple access.The involved problems under different access schemes are all formulated in non-convex forms,which are difficult to be tackled optimally.To solve this class of problem,the successive convex approximation technique is employed to obtain the suboptimal solutions.The numerical results show that the proposed scheme save significant energy consumption compared with the benchmark schemes.
文摘针对经典贪婪算法(greedy)迭代次数多、运算量大的缺点,提出一种基于边缘自适应(margin adaptive,MA)准则的改进贪婪算法来进行正交频分复用(orthogonal frequency division multiplexing,OFDM)系统的自适应比特功率分配。与贪婪算法相比,改进算法通过预分配和迭代分配两部分来降低算法的计算量。在预分配中改进算法通过引入功率利用率函数,对信道条件好的子信道预先加载一部分比特。然后,在迭代分配的过程中,引用分类排序的思想,用一张表格存储子信道的功率变化情况,从而降低算法的复杂度。仿真结果表明,在相同的仿真环境下,改进算法和Greedy算法的误比特性能几乎一致,但改进算法的运行时间更短。
基金Project supported by the Shanghai Pujiang Program (Grant No.08PJ14057)the Science and Technology Commission of Shanghai Municipality (Grant No.08220510900)+1 种基金the Innovation Foundation of Shanghai University (Grant No.SHUCX102153)the Cognitive Communications Consortium of the Worldwide Universities' Network
文摘Cognitive radio （CR） is a promising technology deemed to improve the efficiency of spectrum utilization. This paper considers a spectrum underlay cognitive radio network, in which the cognitive users （CUs） are allowed to use the radio spectrum concurrently with the primary users （PUs） under the interference temperature constraint. We investigate the system performance by using the proposed joint channel and power allocation scheme under two transmit strategies to achieve higher data rates and performance diversity gain respectively. Simulation results show that the proposed scheme provides a significant improvement on the bit error rate （BER） performance and spectrum efficiency of a cognitive wireless network.
基金supported by the National Natural Science Foundation of China (60802033, 60873190)
文摘A novel adaptive power loading algorithm with the constraint of target overall bit error rate （BER） for orthogonal frequency division multiplexing （OFDM） systems is proposed in this article. The proposed algorithm aims to minimize the required transmit power with fixed data rate and uniform （nonadaptive） bit allocation, while guaranteeing the target overall BER. The power loading is based on the unequal-BER （UBER） strategy that allows unequal mean BERs on different subcarriers. The closed-form expressions for optimal BER and power distributions are derived in this article. Simulation results indicate the superiority of the proposed algorithm in terms of BER performance and algorithmic complexity.
