WiFiUS: Device-to-Device Communications at Millimeter-Wave Frequencies

流量的急剧增长--无论是总流量还是每个用户的峰值流量--很快就会超过像LTE这样的当前蜂窝系统的能力。为了应对日益增长的需求，需要开发新的系统，既利用新的频谱使用，又利用新的无线电接入方法。具有这些特征的一种特别有前景的方法是在毫米波频率下操作的设备到设备(D2D)通信。D2D通信利用了这样一个事实，即在许多情况下，例如在社交网络中，两个想要通信的设备彼此非常接近。虽然这样的设备可以通过基础设施节点相互通信，但在设备之间实现直接通信在频谱上要高效得多，特别是对于比小区半径小得多的设备间距离；这还可以实现更高的数据速率。通过利用毫米波频段中的大样本新频谱，可以获得进一步的数据速率增加。在类似WiFi的系统中使用毫米波频率已经标准化，第一批产品正在进入市场。此外，毫米波链路现在也被考虑用于无线接入，即从移动电话到基站或接入点的连接。最近，手机制造商展示了带有毫米波收发器和自适应天线的手机原型，显示了移动应用的实际可行性。这也为基于毫米波的D2D系统提供了可能性。本项目将研究在毫米波频率实现D2D通信的基本问题。关键的是，这样的系统不是简单的“以更高频率运行的常规D2D系统”；相反，在信道建模、链路建立、链路自适应和稳健性方面出现了新的和重要的挑战。为了解决这些问题，我们解决了以下4个主要挑战：(I)使用创新的测量技术和评估，如基于激光扫描的射线跟踪，测量毫米波频率下的D2D传播信道；(Ii)邻居发现，即考虑到设备天线的方向性，找出哪些设备可以彼此通话；(Iii)动态波束形成和波束跟踪，它整合了毫米波信道的一个关键特性，即最强多径分量的方向可以迅速变化；以及(Iv)容量和可靠性调查。该项目的结果将构成支持无线高速连接的系统的基础，这与视频会议、实时游戏、态势感知和许多其他相关。同样重要的是，通过分流耗费资源的连接，可以释放蜂窝资源用于其他应用。

The dramatic increase in traffic - both aggregate, and peak traffic per user - will soon outpace the capabilities of current cellular systems like LTE. To cope with the increased requirements, new systems need to be developed that both exploit the use of new spectrum, and new radio access methods. An especially promising method with those features is device-to-device (D2D) communications operating at millimeter-wave frequencies. D2D communications exploits the fact that in many situations, such as in social networks, two devices that want to communicate are in close proximity to each other. While such devices could talk to each other via infrastructure nodes, it is much more spectrally efficient to enable direct communications between the devices, especially for inter-device distances much smaller than the cell radius; this also enables higher data rates. Further data rate increases can be obtained by exploiting the large swatch of new spectrum in the millimeter-wave frequency bands. The use of millimeter-wave frequencies for WiFi-like systems is has already been standardized and first products are reaching the market. Furthermore, millimeter-wave links are now also considered for wireless access, i.e., connection from a mobile cellphone to a base station or access point. Recently, cellphone manufacturers have demonstrated prototypes of handsets with millimeter-wave transceivers and adaptive antennas, showing the practical viability for mobile applications. This opens up the possibilities for millimeter-wave based D2D systems as well.This project will investigate fundamental questions of realizing D2D communications at millimeter-wave frequencies. Critically, such systems are not simply "regular D2D systems operating at higher frequencies"; rather, new and important challenges arise in the context of channel modeling, link setup, link adaptation, and robustness. To solve these, we tackle the following 4 main challenges: (i) measurement of D2D propagation channels at mm-wave frequencies, using innovative measurement techniques and evaluations such as laser-scanning based ray tracing; (ii) neighbor discovery, i.e., finding which devices can talk to each other, taking into account the directional nature of the device antennas; (iii) dynamic beamforming and beamtracking, which integrates a key property of millimeter-wave channels that the directions of the strongest multipath components can change rapidly; and (iv) capacity and reliability investigations. Results from this project will form the basis for systems that support wireless high-speed connections, as are relevant for video conferences, real-time gaming, situational awareness, and many others. Equally importantly, by offloading resource-consuming connections, cellular resources are freed up for other applications.