Capcity both in uplink and downlink of TD-SCDMA (time division-synchronous code division multiple access) system is studied in a multi-cell environment. The theoretical expressions of the mean of intercell interferenc...Capcity both in uplink and downlink of TD-SCDMA (time division-synchronous code division multiple access) system is studied in a multi-cell environment. The theoretical expressions of the mean of intercell interference in uplink and the mean of sum of power allocation in downlink are given, by which uplink and downlink capacity is analyzed. Furthermore, we give the simulation models for both uplink and downlink capacity. The results from theoretical analysis and simulation fit very well. In the end, the maximum number of users that TD-SCDMA system can serve for 12.2 k speech service is given.展开更多
Time reversal mirror （TRM） can use the physical characteristics of the underwater acoustic （UWA） channel to focus on the desired user in multi-user UWA communication. The active average sound intensity （AASI） de...Time reversal mirror （TRM） can use the physical characteristics of the underwater acoustic （UWA） channel to focus on the desired user in multi-user UWA communication. The active average sound intensity （AASI） detector can estimate all azimuths of users with the same frequency band at the same time in order to achieve directional communication by vector combination. Space-division multiple access （SDMA） based on TRM combined with the AASI detector is proposed in this paper, which can make the capacity of the code division multiple access （CDMA） UWA system significantly increase. The simulation and lake test results show that the 7-user UWA multi-user system can achieve low bit error communication.展开更多
为了解决现有方法难以对宽带跳频时分多址(frequency hopping-time division multiple access,FH-TDMA)辐射源网群定位的问题,提出一种仅利用波达方向(direction of arrival,DOA)信息的多站定位及网群划分方法。首先通过模拟滤波对各站...为了解决现有方法难以对宽带跳频时分多址(frequency hopping-time division multiple access,FH-TDMA)辐射源网群定位的问题,提出一种仅利用波达方向(direction of arrival,DOA)信息的多站定位及网群划分方法。首先通过模拟滤波对各站接收到的信号进行频段划分,通过基于多相滤波的数字信道化方法把信号输出到多个信道中;然后通过直接定位(direct position determination,DPD)算法计算得出各时隙辐射源的位置;最后先通过不同参数的基于密度的噪声应用空间聚类(density-based spatial clustering of applications with noise,DBSCAN)算法选择出最佳的辐射源定位结果,再根据提出的基于先验信息的改进K-means聚类算法进行网群划分。所提方法实现了采样率和信号处理速率的降低,且无需站间严格的时间同步。结果表明,所提方法有效估计出了辐射源的数量、位置,以及网群划分情况。展开更多
车载自组网(vehicular ad hoc network,VANET)中的分布式TDMA方法通常多出没有被节点利用的空闲时隙,未能充分利用无线信道资源,且不能避免由于信道条件差所导致的丢包现象.与此同时,协助通信近年来引起了学术界和工业界的广泛关注,该...车载自组网(vehicular ad hoc network,VANET)中的分布式TDMA方法通常多出没有被节点利用的空闲时隙,未能充分利用无线信道资源,且不能避免由于信道条件差所导致的丢包现象.与此同时,协助通信近年来引起了学术界和工业界的广泛关注,该方法利用了无线信道的广播特性,能够有效地修复信道,提高无线通信的可靠性.针对VANET应用场合,提出了一种MAC层数据协助重发方法,即协助分布式TDMA方法(cooperative distributed TDMA,Co-DTDMA).在Co-DTDMA中,如果源节点未成功发送数据,则附近的邻居节点利用未分配的空闲时隙协助重发源节点数据.与传统的协助通信方法不同,Co-DTDMA中的所有操作都以分布式方式进行,不依赖任何中心控制节点,因而适应于VANET应用场合.此外,Co-DTDMA仅利用未分配的空闲时隙协助重发数据,不影响网络中的正常数据传输.理论分析和仿真实验表明:Co-DTDMA显著地提高了数据成功接收概率,降低了数据传输时延.展开更多
文摘Capcity both in uplink and downlink of TD-SCDMA (time division-synchronous code division multiple access) system is studied in a multi-cell environment. The theoretical expressions of the mean of intercell interference in uplink and the mean of sum of power allocation in downlink are given, by which uplink and downlink capacity is analyzed. Furthermore, we give the simulation models for both uplink and downlink capacity. The results from theoretical analysis and simulation fit very well. In the end, the maximum number of users that TD-SCDMA system can serve for 12.2 k speech service is given.
基金supported by the National Natural Science Foundation of China(6147113751179034)+3 种基金the Ships Pre-research Support Technology Fund(13J3.1.5)the Natural Science Foundation of Heilongjiang Province(F201109)the Innovation Talents of Science and the Technology Research Projects of Harbin(2013RFQXJ101)the National Defense Basic Technology Research(JSJC2013604C012)
文摘Time reversal mirror （TRM） can use the physical characteristics of the underwater acoustic （UWA） channel to focus on the desired user in multi-user UWA communication. The active average sound intensity （AASI） detector can estimate all azimuths of users with the same frequency band at the same time in order to achieve directional communication by vector combination. Space-division multiple access （SDMA） based on TRM combined with the AASI detector is proposed in this paper, which can make the capacity of the code division multiple access （CDMA） UWA system significantly increase. The simulation and lake test results show that the 7-user UWA multi-user system can achieve low bit error communication.
文摘为了解决现有方法难以对宽带跳频时分多址(frequency hopping-time division multiple access,FH-TDMA)辐射源网群定位的问题,提出一种仅利用波达方向(direction of arrival,DOA)信息的多站定位及网群划分方法。首先通过模拟滤波对各站接收到的信号进行频段划分,通过基于多相滤波的数字信道化方法把信号输出到多个信道中;然后通过直接定位(direct position determination,DPD)算法计算得出各时隙辐射源的位置;最后先通过不同参数的基于密度的噪声应用空间聚类(density-based spatial clustering of applications with noise,DBSCAN)算法选择出最佳的辐射源定位结果,再根据提出的基于先验信息的改进K-means聚类算法进行网群划分。所提方法实现了采样率和信号处理速率的降低,且无需站间严格的时间同步。结果表明,所提方法有效估计出了辐射源的数量、位置,以及网群划分情况。
文摘车载自组网(vehicular ad hoc network,VANET)中的分布式TDMA方法通常多出没有被节点利用的空闲时隙,未能充分利用无线信道资源,且不能避免由于信道条件差所导致的丢包现象.与此同时,协助通信近年来引起了学术界和工业界的广泛关注,该方法利用了无线信道的广播特性,能够有效地修复信道,提高无线通信的可靠性.针对VANET应用场合,提出了一种MAC层数据协助重发方法,即协助分布式TDMA方法(cooperative distributed TDMA,Co-DTDMA).在Co-DTDMA中,如果源节点未成功发送数据,则附近的邻居节点利用未分配的空闲时隙协助重发源节点数据.与传统的协助通信方法不同,Co-DTDMA中的所有操作都以分布式方式进行,不依赖任何中心控制节点,因而适应于VANET应用场合.此外,Co-DTDMA仅利用未分配的空闲时隙协助重发数据,不影响网络中的正常数据传输.理论分析和仿真实验表明:Co-DTDMA显著地提高了数据成功接收概率,降低了数据传输时延.
