In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging ...In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.展开更多
PFA管材耐腐蚀性好、性能稳定,被广泛应用在半导体等行业的药液运输中,为精确控制药液的用时和用量,需要研究小管径PFA管的非接触式流量测量方法。本文使用超声阵列外卡探头在PFA细管上激励超声导波,并利用导波测量流量。首先比较超声...PFA管材耐腐蚀性好、性能稳定,被广泛应用在半导体等行业的药液运输中,为精确控制药液的用时和用量,需要研究小管径PFA管的非接触式流量测量方法。本文使用超声阵列外卡探头在PFA细管上激励超声导波,并利用导波测量流量。首先比较超声斜探头模态选择和阵列探头模态选择原理的不同,说明阵列探头的频率选择特性,进而设计阵列探头阵元宽度、厚度并制作了三种间距的阵列探头,通过频率扫描得到阵列探头的激励接收特性,比较分析了阵列探头的模态选择效果,并进行了流量测量实验。结果表明阵列探头可增强接收信号强度,提高测量灵敏度,改变阵列间距可以选择不同导波模态,在3 mm PFA管上选择L(0,5)导波模态时流速范围0~6.70 m/s内的测量结果误差限为±0.22 m/s。展开更多
To relieve traliic overhead induced by active probing based methods, a new fault detection method, whose key is to divide the detection process into multiple stages, is proposed in this paper. During each stage, only ...To relieve traliic overhead induced by active probing based methods, a new fault detection method, whose key is to divide the detection process into multiple stages, is proposed in this paper. During each stage, only a small region of the network is detected by using a small set of probes. Meanwhile, it also ensures that the entire network can be covered alter multiple detection stages. This method can guarantee that the traffic used by probes during each detection stage is small sufficiently so that the network can operate without severe disturbance from probes. Several simulation results verify the effectiveness of the proposed method.展开更多
基金supported by the State Major Science and Technology Special Projects under Grant No. 2018ZX03001028-003
文摘In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.
文摘PFA管材耐腐蚀性好、性能稳定,被广泛应用在半导体等行业的药液运输中,为精确控制药液的用时和用量,需要研究小管径PFA管的非接触式流量测量方法。本文使用超声阵列外卡探头在PFA细管上激励超声导波,并利用导波测量流量。首先比较超声斜探头模态选择和阵列探头模态选择原理的不同,说明阵列探头的频率选择特性,进而设计阵列探头阵元宽度、厚度并制作了三种间距的阵列探头,通过频率扫描得到阵列探头的激励接收特性,比较分析了阵列探头的模态选择效果,并进行了流量测量实验。结果表明阵列探头可增强接收信号强度,提高测量灵敏度,改变阵列间距可以选择不同导波模态,在3 mm PFA管上选择L(0,5)导波模态时流速范围0~6.70 m/s内的测量结果误差限为±0.22 m/s。
文摘To relieve traliic overhead induced by active probing based methods, a new fault detection method, whose key is to divide the detection process into multiple stages, is proposed in this paper. During each stage, only a small region of the network is detected by using a small set of probes. Meanwhile, it also ensures that the entire network can be covered alter multiple detection stages. This method can guarantee that the traffic used by probes during each detection stage is small sufficiently so that the network can operate without severe disturbance from probes. Several simulation results verify the effectiveness of the proposed method.