As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. Thi...As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.展开更多
随着高集成小型化射频技术的发展,多信道定向天线成为提升网络组网容量的新手段,基于此主要研究了无线自组网中基于多信道定向天线的跨层组网协议。以优化的链路状态路由(Optimized Link State Routing,OLSR)协议为基础,充分考察了多信...随着高集成小型化射频技术的发展,多信道定向天线成为提升网络组网容量的新手段,基于此主要研究了无线自组网中基于多信道定向天线的跨层组网协议。以优化的链路状态路由(Optimized Link State Routing,OLSR)协议为基础,充分考察了多信道-单节点各无线信道的时变性质。首先,通过跨层信息共享节点的邻居关系,削减协议开销;其次,跨层获取节点的当前发送速率、负载,并与跳数相结合,设计了一种跨层时变的路由度量方法;最后,充分发挥多信道优势,提出了一种零耦合的多径路由协议。仿真结果表明,所提的多信道跨层多径路由协议能够显著降低网络层的路由开销,提升网络吞吐量。展开更多
频率偏移估计是OFDM(Orthogonal Frequency Division Multiplexing)的关键技术。该文提出了在一个 OFDM符号内利用两个重复的CAZAC(Constant Amplitude Zero Auto Correlation)序列进行频率偏移估计的新方法, 估计范围可达整个OFDM带宽...频率偏移估计是OFDM(Orthogonal Frequency Division Multiplexing)的关键技术。该文提出了在一个 OFDM符号内利用两个重复的CAZAC(Constant Amplitude Zero Auto Correlation)序列进行频率偏移估计的新方法, 估计范围可达整个OFDM带宽。用于同步的训练序列还可用于信道估计和均衡,这将提高系统的数据传输效率。 此算法同步精度达到了Schmidl提出的Cramer-Rao bound,有效性在AWGN和Rayleigh多径信道下得到了验证。展开更多
文摘As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.
文摘随着高集成小型化射频技术的发展,多信道定向天线成为提升网络组网容量的新手段,基于此主要研究了无线自组网中基于多信道定向天线的跨层组网协议。以优化的链路状态路由(Optimized Link State Routing,OLSR)协议为基础,充分考察了多信道-单节点各无线信道的时变性质。首先,通过跨层信息共享节点的邻居关系,削减协议开销;其次,跨层获取节点的当前发送速率、负载,并与跳数相结合,设计了一种跨层时变的路由度量方法;最后,充分发挥多信道优势,提出了一种零耦合的多径路由协议。仿真结果表明,所提的多信道跨层多径路由协议能够显著降低网络层的路由开销,提升网络吞吐量。
文摘频率偏移估计是OFDM(Orthogonal Frequency Division Multiplexing)的关键技术。该文提出了在一个 OFDM符号内利用两个重复的CAZAC(Constant Amplitude Zero Auto Correlation)序列进行频率偏移估计的新方法, 估计范围可达整个OFDM带宽。用于同步的训练序列还可用于信道估计和均衡,这将提高系统的数据传输效率。 此算法同步精度达到了Schmidl提出的Cramer-Rao bound,有效性在AWGN和Rayleigh多径信道下得到了验证。
