共查询到20条相似文献,搜索用时 109 毫秒
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文章考虑下行链路D2D通信对复用同小区的蜂窝资源,不同于传统的基于总功率约束的赋形策略,我们提出了基于单根天线功率约束的波束赋形策略。TD-LTE系统采用的是时分双工,上下行信道具有互易性,因此通过对上行信道信息的获取,可以得到下行信道的信道状态信息(Channel Station Information,CSI),从而有效地实现波束赋形。在CSI已知的情况下,我们提出了一种高效的算法寻找最优的波束赋形策略,使得经典的基于最大最小信干比的问题能够被重写为标准的二阶锥规划(SCOP),从而使最优的目标能够通过标准的二阶锥规划求解器求解。同时,为了减少由于D2D通信对加入给蜂窝网络带来的干扰,一种D2D状态搜索算法被提出,它能够选择最优的D2D通信对加入蜂窝网络中,使得系统的吞吐量得到提升。 相似文献
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针对毫米波大规模多入多出系统在射频链路数量有限时,波束域信道估计是一个有挑战性的问题,提出一种基于优化BM3D的信道估计方案。利用基于三维透镜的多入多出系统信道矩阵可被视为二维自然图像的结构特性,将图像重构技术融入信道估计。BM3D 是目前最精确的图像去噪算法之一,通过块匹配实现分组,利用三维变换域的收缩完成协同滤波。考虑信道的稀疏特性和路径的聚类特性,对BM3D算法进一步优化以提高性能。仿真结果表明,提出的优化BM3D方案在所有考虑的信噪比区域均能取得令人满意的信道估计精度。 相似文献
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ISDN(综合业务数字网)控制器起用户网络接口作用,这种接口可为一个或多个ISDN终端服务。PEB 2070微片提供两条64 kb/s的线路交换数字信道(即两条B信道)和一条面向信息的16 kb/s的D信道。D信道载送信令信息、遥测数据和分组交换数据。在D信道上的链路访问规约(LAPD)是以X.25通信规约LAPS为基础的。 相似文献
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针对设备到设备(D2D)直连通信网络传统最优资源分配算法在随机信道时延、信道估计误差影响下鲁棒性弱的问题,该文在考虑参数不确定性影响的条件下,提出D2D用户总能效最大的鲁棒资源分配算法。考虑干扰功率门限、用户最小速率需求、最大传输功率和子信道分配约束,建立了下垫式频谱共享模式下多用户D2D网络资源分配模型。基于有界信道不确定性模型,利用最坏准则方法将原非凸鲁棒资源分配问题转换为确定性的凸优化问题。然后利用拉格朗日对偶理论求得资源分配的解析解。仿真结果表明所提出的算法具有很好的鲁棒性。 相似文献
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Harmonic broadcasting for video-on-demand service 总被引:5,自引:0,他引:5
Li-Shen Juhn Li-Ming Tseng 《Broadcasting, IEEE Transactions on》1997,43(3):268-271
Using conventional broadcasting, if we want to support a 120-minute popular movie every 10 minutes, we need 12 video channels. Assuming the set-top box at the client end can buffer portions of the playing video on a disk, pyramid broadcasting schemes can reduce the bandwidth requirements to 5.7 channels. We present a new scheme which only needs 3.2 channels. For a movie with length D minutes, if we want to reduce the viewer waiting time to D/N minutes, we only need to allocate H(N) video channels to broadcast the movie periodically, where H(N) is the harmonic number of N, H(N)=1+1/2+…+1/N. In order to support video-on-demand service for a popular movie, the new scheme greatly reduces the bandwidth requirements 相似文献
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在传统的VOD广播中,如果希望每10分钟得到一次收看一部120分钟影片的机会,需要12个视频频道,假设客户端能够在硬盘上缓存影片某些部分,金字塔广播方案能够将带宽缩减到5.7个频道。幂级分配广播方案则仅需要4个频道,对于长度为D分钟的影片,如果想要将观看者的等待时间缩减到D/M分钟,仅需要安排N(M)个视频频道来循环广播该影片,其中N(M)=log2(M+1),此方案大幅减少了单个视频点服务的占用 相似文献
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Li-Shen Juhn Li-Ming Tseng 《Broadcasting, IEEE Transactions on》1998,44(2):182-185
As we support video-on-demand (VOD) service with batching schemes, the bandwidth requirement will be very large for a popular movie. For a hot video, fast data broadcasting scheme substantially reduce the bandwidth requirements as compared with batching schemes. However, the fast data broadcasting scheme needs to predict which movie is hot. If the prediction is not accurate, the allocated bandwidth will be wasted. This paper presents a new data broadcasting scheme for VOD service. For a movie, as it is popular, the new scheme will work like the fast data broadcasting scheme to save the communication bandwidth. If there is no request for the movie, the new scheme will not allocate bandwidth for the movie. Therefore, the bandwidth allocation for a movie is always efficient whether or not the movie is popular 相似文献
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Li-Shen Juhn Li-Ming Tseng 《Broadcasting, IEEE Transactions on》1998,44(1):100-105
Using multiple channels to broadcast a popular video can reduce the viewer's waiting time to approach video-on-demand service. For a given bandwidth allocation, pyramid broadcasting schemes can provide users with shorter waiting time as compared with conventional broadcasting schemes. However, for a 120-minute movie, the waiting time is only reduced to 20 minutes as we allocate 4 video channels for the movie. The harmonic broadcasting scheme can reduce the waiting time to 4 minutes but it can not support the live telecast. This paper presents a new broadcasting scheme, which can support live videos and reduce the waiting time to 8 minutes for the above case. With the same waiting requirement for a hot video, the new scheme can greatly reduce the bandwidth requirements and provide heterogeneous users' services 相似文献
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Marcelo Bertalmío Vicent Caselles Alvaro Pardo 《IEEE transactions on image processing》2007,16(9):2333-2347
Here, we present an efficient method for movie denoising that does not require any motion estimation. The method is based on the well-known fact that averaging several realizations of a random variable reduces the variance. For each pixel to be denoised, we look for close similar samples along the level surface passing through it. With these similar samples, we estimate the denoised pixel. The method to find close similar samples is done via warping lines in spatiotemporal neighborhoods. For that end, we present an algorithm based on a method for epipolar line matching in stereo pairs which has per-line complexity O (N), where N is the number of columns in the image. In this way, when applied to the image sequence, our algorithm is computationally efficient, having a complexity of the order of the total number of pixels. Furthermore, we show that the presented method is unsupervised and is adapted to denoise image sequences with an additive white noise while respecting the visual details on the movie frames. We have also experimented with other types of noise with satisfactory results. 相似文献
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Diana Rieger Lena Frischlich Fabia Högden Robert Kauf Kristina Schramm Erzsébet Tappe 《The Journal of communication》2015,65(2):351-372
Entertainment media are found to evoke appreciation when they deal with topics such as moral virtues, values, or questions of sense in life. Drawing upon terror management theory, we question whether meaningful media can also serve as anxiety buffer shielding against the threat of death, as they transport cultural worldviews and enhance self‐esteem among recipients. Results of an experimental study (N = 122) confirmed that participants under mortality salience appreciated a meaningful movie more than participants in a control condition. Further, only a meaningful movie, not a pleasurable or an informative film, decreased the necessity to activate further anxiety buffers after mortality salience. The findings are discussed in relation to entertainment media as means to handle existential fears. 相似文献
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Here, we present an efficient method for movie denoising that does not require any motion estimation. The method is based on the well-known fact that averaging several realizations of a random variable reduces the variance. For each pixel to be denoised, we look for close similar samples along the level surface passing through it. With these similar samples, we estimate the denoised pixel. The method to find close similar samples is done via warping lines in spatiotemporal neighborhoods. For that end, we present an algorithm based on a method for epipolar line matching in stereo pairs which has per-line complexity O(N) , where is the number of columns in the image. In this way, when applied to the image sequence, our algorithm is computationally efficient, having a complexity of the order of the total number of pixels. Furthermore, we show that the presented method is unsupervised and is adapted to denoise image sequences with an additive white noise while respecting the visual details on the movie frames. We have also experimented with other types of noise with satisfactory results. 相似文献
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《Latin America Transactions, IEEE (Revista IEEE America Latina)》2006,4(5):379-384
This paper presents the development of the main modules of a highly interactive system for security training, The system allows the security professionals to feel as if they were in a real danger situation, very close to the one they may find in their work activities. Such situations create conditions for a better training and skills achievement. In order to produce the interactivity, the system exhibits a 2D movie, in real size (1:1), showing scenes and scenarios close to the reality of the professional under training. During the movie an unexpected situation of danger emerges and the user has to make quick decisions to circumvent the problem. Depending on the reactions of the user, the automated system chooses the best sequence for the movie. Afterwards, the reactions and decision taken by the users will be evaluated by computer software to determine his/her performance. 相似文献
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《Spectrum, IEEE》2009,46(5):28-33
It's 7:50 p.m. on 1 October 2007 at AT&T Labs, in Florham Park, N.J., and three of us are frantically hitting the "refresh" buttons on our browsers. We have just submitted our latest entry in the year-old Netflix Prize competition, which offers a grand prize of US $1 million for an algorithm that's 10 percent more accurate than the one Netflix uses to predict customers' movie preferences. Although we have not reached that milestone, we are hoping at least to do better than anyone else has done so far; if we can make it to 8 p.m. with the best score, we'll win a $50,000 Progress Prize. 相似文献