Data Mining Practical Machine Learning Tools and Techniques

Millimeter wave (mmWave) signals experience orders-of-magnitude more pathloss than the microwave signals currently used in most wireless applications and all cellular systems. MmWave systems must therefore leverage large antenna arrays, made possible by the decrease in wavelength, to combat pathloss with beamforming gain. Beamforming with multiple data streams, known as precoding, can be used to further improve mmWave spectral efficiency. Both beamforming and precoding are done digitally at baseband in traditional multi-antenna systems. The high cost and power consumption of mixed-signal devices in mmWave systems, however, make analog processing in the RF domain more attractive. This hardware limitation restricts the feasible set of precoders and combiners that can be applied by practical mmWave transceivers. In this paper, we consider transmit precoding and receiver combining in mmWave systems with large antenna arrays. We exploit the spatial structure of mmWave channels to formulate the precoding/combining problem as a sparse reconstruction problem. Using the principle of basis pursuit, we develop algorithms that accurately approximate optimal unconstrained precoders and combiners such that they can be implemented in low-cost RF hardware. We present numerical results on the performance of the proposed algorithms and show that they allow mmWave systems to approach their unconstrained performance limits, even when transceiver hardware constraints are considered.

Spatially Sparse Precoding in Millimeter Wave MIMO Systems

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

In-band full-duplex (IBFD) operation has emerged as an attractive solution for increasing the throughput of wireless communication systems and networks. With IBFD, a wireless terminal is allowed to transmit and receive simultaneously in the same frequency band. This tutorial paper reviews the main concepts of IBFD wireless. One of the biggest practical impediments to IBFD operation is the presence of self-interference, i.e., the interference that the modem's transmitter causes to its own receiver. This tutorial surveys a wide range of IBFD self-interference mitigation techniques. Also discussed are numerous other research challenges and opportunities in the design and analysis of IBFD wireless systems.

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In-Band Full-Duplex Wireless: Challenges and Opportunities

In-band full-duplex (IBFD) operation has emerged as an attractive solution for increasing the throughput of wireless communication systems and networks. With IBFD, a wireless terminal is allowed to transmit and receive simultaneously in the same frequency band. This tutorial paper reviews the main concepts of IBFD wireless. Because one the biggest practical impediments to IBFD operation is the presence of self-interference, i.e., the interference caused by an IBFD node's own transmissions to its desired receptions, this tutorial surveys a wide range of IBFD self-interference mitigation techniques. Also discussed are numerous other research challenges and opportunities in the design and analysis of IBFD wireless systems.

A large number of traffic collisions occur as a result of obstructed sight lines, such that even an advanced driver assistance system would be unable to prevent the crash. Recent work has proposed the use of around-the-corner radar systems to detect vehicles, pedestrians, and other road users in these occluded regions. Through comprehensive measurement, we show that these existing techniques cannot sense occluded moving objects in many important real-world scenarios. To solve this problem of limited coverage, we leverage multiple, curved reflectors to provide comprehensive coverage over the most important locations near an intersection. In scenarios where curved reflectors are insufficient, we evaluate the relative benefits of using additional flat planar surfaces. Using these techniques, we more than double the probability of detecting a vehicle near the intersection in three real urban locations, and enable NLoS radar sensing using an entirely new class of reflectors.

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Mosaic: leveraging diverse reflector geometries for omnidirectional around-corner automotive radar

The embodiment of the invention provides a video call method and device based on deep imitation learning. The method comprises the following steps: obtaining the transmission information of a previoustransmission time slot for the current transmission time slot of a video call; wherein the transmission information comprises transmission layer information and application layer information; inputting the transmission information into a code rate optimization network model to obtain a transmission code rate of the current transmission time slot; wherein the code rate optimization network model is a model obtained by training according to a training set, and the training set comprises real transmission information and a real transmission code rate of each transmission time slot in the samplevideo call; and sending the video call data to the receiving end based on the transmission code rate of the current transmission time slot. Therefore, the proper transmission code rate in the video call is determined in real time, and the video call quality is improved.

Video call method and device based on deep imitation learning

Porcine teschovirus (PTV) is a causative agent of polioencephalomyelitis, encephalomyelitis, reproductive disorders and gastrointestinal and respiratory diseases in swine. In the present study, the PTV2 GX/2020 strain was isolated from pig intestinal tissue through the use of ST cells. Phylogenetic analysis of VP1 nucleotide sequences indicated that the GX/2020 isolate is closely related to PTV2. Furthermore, the full-length cDNA of an infectious GX/2020 clone was constructed using seamless ligation technology. The genome sequence of the rescued virus is largely consistent with the sequence of the parental virus, and it exhibits viral growth properties. The PTV2 virus was successfully isolated in the present study, and the reverse-genetic platform provides a foundation for studies of the pathogenic mechanisms of porcine teschovirus.

Construction and characterization of the full-length cDNA of an infectious clone of emerging porcine teschovirus-2.

The ubiquity of mobile camera devices has been triggering an outcry of privacy concerns, whereas privacy protection still relies on the compliance of the photographer or camera hardware, which can hardly be guaranteed in practice. In this demo, we introduce LiShield, which automatically protects a physical scene against photographing, by illuminating it with smart LEDs flickering in a specialized waveform. We use a model-driven approach to optimize the waveform, so as to ensure protection against the (uncontrollable) cameras and potential image-processing based attacks. We have also designed mechanisms to unblock authorized cameras and enable graceful degradation under strong ambient light interference. This demo will show our prototype implementation, with simple on-site experiments that demonstrate how LiShield effectively destroys unauthorized photo capturing.

Demo: LiShield: Privacy Protection of Physical Environment Against Photographing

In order to meet the high data rate requirements of emerging roadway use cases, mmWave vehicular communications will be needed. This work studies the ability of vehicles to communicate with a Roadside Unit (RSU) placed at an intersection. Practical mmWave radios utilize a codebook, a discrete set of analog beams, that is periodically searched during runtime to find the optimal beam to use for each receiver. This search creates overhead as the wireless channel is not used for communication while this beam search is happening. This work focuses on reducing the overhead of beam training by optimizing the site-specific codebook design of a RSU. Owing to the sparsity of the mmWave channel and the user distribution for vehicles, it is found that 85% of beams can be removed from the codebook with zero-impact. By carefully selecting the usage of wide beams the codebook size can be further reduced to just 64 beams while still providing omni-directional coverage for an intersection. Other research thrusts have focused on attempting to augment or remove beam training entirely; however, this necessitates a change to the PHY layer. Codebook optimization achieves approximately 80% of the communications performance that would be achieved if beam training overhead could be completely removed while only requiring a radio configuration update. Thus, this work finds that today’s commercial mmWave radios are sufficient for deployments in RSUs. To validate the proposed codebook optimization algorithm, a detailed mmWave ray tracing framework that encompasses 3D environmental information and material properties of reflectors is developed.

Xinyu Zhang

Papers

Mosaic: leveraging diverse reflector geometries for omnidirectional around-corner automotive radar

Video call method and device based on deep imitation learning

Construction and characterization of the full-length cDNA of an infectious clone of emerging porcine teschovirus-2.

Demo: LiShield: Privacy Protection of Physical Environment Against Photographing

Low Overhead Codebook Design for mmWave Roadside Units Placed at Smart Intersections