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Jianzhong Charlie Zhang

Jianzhong Charlie Zhang
Samsung | samsung · Research and Development

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184
Publications
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Publications

Publications (184)
Preprint
Full-text available
Beam management (BM), i.e., the process of finding and maintaining a suitable transmit and receive beam pair, can be challenging, particularly in highly dynamic scenarios. Side-information, e.g., orientation, from on-board sensors can assist the user equipment (UE) BM. In this work, we use the orientation information coming from the inertial measur...
Preprint
Full-text available
Beam correspondence, or downlink-uplink (DL-UL) beam reciprocity, refers to the assumption that the best beams in the DL are also the best beams in the UL. This is an important assumption that allows the existing beam management framework in 5G to rely heavily on DL beam sweeping and avoid UL beam sweeping: UL beams are inferred from the measuremen...
Article
As the pace of global 5G network deployments accelerates, now is the moment for the cellular industry to realize 6G cellular communication. In this article, modular massive multiple-in-put multiple-output (mmMIMO) is presented as one candidate technology for 6G to improve the spectral efficiency in low-frequency bands. The 5G New Radio pushed the b...
Article
Future cellular networks will increasingly rely on the millimeter-wave bands to increase capacity. Migrating to ever higher carrier frequencies will require increasingly directional beamforming to establish and maintain the link. Intelligent beam management (BM) protocols will be critical for establishing and maintaining connections between the bas...
Article
Full-text available
Finding the optimal transmit and receive beam pair for reliable communication can be challenging, especially in highly dynamic environments. Side-information from on-board sensors at the user equipment (UE) can be used to aid the beam management (BM) process. In this work, we use the orientation information coming from inertial measurement unit (IM...
Preprint
Full-text available
Estimating downlink (DL) channel state information (CSI) in frequency division duplex (FDD) massive multi-input multi-output (MIMO) systems generally requires downlink pilots and feedback overheads. Accordingly, this paper investigates the feasibility of zero-feedback FDD massive MIMO systems based on channel extrapolation. We use the high-resoluti...
Article
Full-text available
Estimating downlink (DL) channel state information (CSI) in frequency division duplex (FDD) massive multi-input multi-output (MIMO) systems generally requires downlink pilots and feedback overheads. Accordingly, this paper investigates the feasibility of zero-feedback FDD massive MIMO systems based on channel extrapolation. We use the high-resoluti...
Article
Spatial spectrum sensing (SSS) enables mobile devices to sense the spatial spectrum holes and reuse the scarce spectrum opportunistically. In this paper, we model and analyze the SSS in uplink two-tier user-centric deployed heterogeneous networks (HetNets) where secondary users (SUs) sense the spectrum holes of cellular users. In the two-tier user-...
Article
Full-text available
Mobile network operators (MNOs) are in the process of overlaying their conventional macro cellular networks with shorter range cells such as outdoor pico cells. The resultant increase in network complexity creates substantial overhead in terms of operating expenses, time, and labor for their planning and management. Artificial intelligence (AI) offe...
Preprint
In this paper, we investigate learning-based MIMO-OFDM symbol detection strategies focusing on a special recurrent neural network (RNN) -- reservoir computing (RC). We first introduce the Time-Frequency RC to take advantage of the structural information inherent in OFDM signals. Using the time domain RC and the time-frequency RC as the building blo...
Article
Increased pilot overhead is one of the major issues for 5G FD-MIMO systems. In this paper, we introduce FDMIMO systems with pilot-data superposition to reduce uplink pilot overhead and investigate the impact of superimposed pilots on the overall network performance of the corresponding FDMIMO system. Pilot-data superposition can certainly improve t...
Article
Full-text available
Current trends in spectrum regulation show that more and more unlicensed and shared spectrum bands are poised to be opened up for mobile communication. However, the question remains how to best utilize this spectrum and build efficient networks, and if the time has come for newer approaches to be considered for the next generation system. In this w...
Article
Full-text available
Providing a high quality video streaming experience in a mobile data network via the ubiquitous HTTP Adaptive Streaming (HAS) protocol is challenging. This is largely because HAS traffic arrives as regular Internet Protocol (IP) packets, indistinguishable from those of other data services. This paper presents real-time network-based Machine Learnin...
Preprint
Full-text available
This paper studies the effect of the user hand grip on the design of beamforming codebooks for 5G millimeter-wave (mmWave) mobile handsets. The high-frequency structure simulator (HFSS) is used to characterize the radiation fields for fourteen possible handgrip profiles based on experiments we conducted. The loss from hand blockage on the antenna g...
Preprint
Full-text available
A beam codebook of 5G millimeter wave (mmWave) for data communication consists of multiple high-peak-gain beams to compensate the high pathloss at the mmWave bands. These beams also have to point to different angular directions, such that by performing beam searching over the codebook, a good mmWave signal coverage over the full sphere around the t...
Article
Full-text available
A beam codebook of 5G millimeter wave (mmWave) for data communication consists of multiple high-peak-gain beams to compensate the high pathloss at the mmWave bands. These beams also have to point to different angular directions, such that by performing beam searching over the codebook, a good mmWave signal coverage over the full sphere around the t...
Preprint
Full-text available
Mobile Network Operators (MNOs) are in process of overlaying their conventional macro cellular networks with shorter range cells such as outdoor pico cells. The resultant increase in network complexity creates substantial overhead in terms of operating expenses, time, and labor for their planning and management. Artificial intelligence (AI) offers...
Preprint
Full-text available
Beamforming in multiple input multiple output (MIMO) systems is one of the key technologies for modern wireless communication. Creating appropriate sector-specific broadcast beams are essential for enhancing the coverage of cellular network and for improving the broadcast operation for control signals. However, in order to maximize the coverage, pa...
Article
Full-text available
This paper contributes a comprehensive study on the effect of the user hand grip on the design of 5G millimeter-wave (mmWave) mobile handsets, specifically in terms of antenna module placement and the beamforming codebook. The high-frequency structure simulator (HFSS) is used to characterize the radiation fields for different antenna placements and...
Preprint
Full-text available
This paper investigates the capability of millimeter-wave (mmWave) channel sounders with phased arrays to perform super-resolution parameter estimation, i.e., determine the parameters of multipath components (MPC), such as direction of arrival and delay, with resolution better than the Fourier resolution of the setup. We analyze the question both g...
Article
Outdoor to indoor penetration loss is one of the crucial challenges faced at millimeter-wave frequencies. This paper presents the results from 28 GHz channel sounding campaigns performed to investigate the impact of this phenomenon on the wireless propagation channel characteristics in small cell and fixed wireless access scenarios. The measurement...
Conference Paper
Full-text available
This paper investigates the effects of a human body shadowing for a device-to-device (D2D) communications scenario at 28 GHz. The measurements are performed with a real-time channel sounder equipped with fast-switching phased antenna arrays, which enables the directionally resolved wideband measurement of dynamic effects. By exploiting the phase co...
Conference Paper
Spatial correlation across an antenna array is known to be detrimental to the terminal signal-to-interference-plus-noise-ratio (SINR) and system spectral efficiency. For a downlink multiuser multiple-input multiple-output system (MU-MIMO), we show that the widely used, yet overly simplified, correlation models which generate fixed correlation patte...
Preprint
In this paper, we present a novel real-time multiple-input-multiple-output (MIMO) channel sounder for the 28 GHz band. Until now, most investigations of the directional characteristics of millimeter-wave channels have used mechanically rotating horn antennas. In contrast, the sounder presented here is capable of performing horizontal and vertical b...
Article
Multidimensional characterization of outdoor urban macrocellular propagation channels is essential for the analysis and design of next-generation (5G and beyond) cellular massive MIMO (multiple-input-multiple-output) systems. Since most massive MIMO arrays will extend in two or three dimensions, an understanding of 3-D parameters (i.e., azimuth and...
Article
Full-text available
This paper present the results from a 28 GHz channel sounding campaign performed to investigate the effects of outdoor to indoor penetration on the wireless propagation channel characteristics for an urban microcell in a fixed wireless access scenario. The measurements are performed with a real-time channel sounder, which can measure path loss up t...
Article
Full-text available
This paper presents results from the (to our knowledge) first dynamic double-directionally resolved measurement campaign at mm-wave frequencies for an outdoor microcellular scenario. The measurements are performed with USC's real-time channel sounder equipped with phased array antennas that can steer beams electrically in microseconds, allowing dir...
Article
Full-text available
This paper presents results from the (to our knowledge) first double-directionally resolved measurement campaign at mm-wave frequencies in a suburban microcell. The measurements are performed with a real-time channel sounder equipped with phased antenna arrays that allows electrical beam steering in microseconds, and which can measure path-loss of...
Article
Full-text available
The stationarity region, i.e., the area in which the statistics of a propagation channel remain constant, is an important measure of the propagation channel, and essential for efficient system design. This paper presents what is to our knowledge the first extensive measurement campaign for measuring the stationarity region of MIMO mm-wave channels....
Article
This paper considers a fundamental issue of path loss (PL) modeling in urban micro cell (UMi) environments, namely the spatial consistency of the model as the mobile station (MS) moves along a trajectory through street canyons. The work is motivated by the observed non-stationarity of the PL. We show that the traditional model of power law PL plus...
Article
Full-text available
Cell search is the process for a user to detect its neighboring base stations (BSs) and make a cell selection decision. Due to the importance of beamforming gain in millimeter wave (mmWave) and massive MIMO cellular networks, the directional cell search delay performance is investigated. A cellular network with fixed BS and user locations is consid...
Article
Full-text available
In order to meet the challenge of increasing data-rate demand as well as the form factor limitation of the base station (BS), 3-D massive multiple-input multiple-output (MIMO) technology has been introduced as one of the enabling technologies for fifth generation mobile cellular systems. In 3-D massive MIMO systems, a BS will rely on the uplink sou...
Article
Full-text available
Spectrum scarcity has driven enhancements of Long-Term Evolution (LTE) in utilizing unlicensed bands in conjunction with licensed bands for delivering mobile data, resulting in the introduction of LTE unlicensed technologies such as Rel-13 LTE–Licensed-Assisted Access (LAA), Rel-14 LTE–Enhanced Licensed-Assisted Access (eLAA), and LTE-Unlicensed (L...
Article
Massive MIMO (Multi-Input Multi-Output) is shown to significantly increase spectral efficiency by exploiting a large number of antennas to support high order multiuser MIMO. In 3GPP Release-13, Full-Dimension MIMO (FD-MIMO) technology was introduced to address practical aspects for massive MIMO in cellular systems; extensive simulations show 2- 4X...
Article
This paper presents the next evolution of FD-MIMO technology for beyond 5G, where antennas of the FD-MIMO system are placed in a distributed manner throughout the cell in a multi-cell deployment scenario. This system, referred to as Distributed FD-MIMO (D-FD-MIMO) system, is capable of providing higher cell average throughput as well as more unifor...
Article
3-dimensional Multiple-Input Multiple-Output (3D MIMO) systems have received great interest recently because of the spatial diversity advantage and capability for full-dimensional beamforming, making them promising candidates for practical realization of massive MIMO. In this paper, we present a low-cost test equipment (channel sounder) and post-pr...
Article
Full-text available
In this paper, we present a novel real-time MIMO channel sounder for 28 GHz. Until now, the common practice to investigate the directional characteristics of millimeter-wave channels has been using a rotating horn antenna. The sounder presented here is capable of performing horizontal and vertical beam steering with the help of phased arrays. Thank...
Article
This paper investigates the effectiveness of multipath-decorrelating antenna motion in reducing the initialization time of Global Navigation Satellite System (GNSS) receivers employing low-cost single-frequency antennas for carrier-phase differential GNSS (CDGNSS) positioning. Fast initialization times with low-cost antennas will encourage the expa...
Conference Paper
Initial access is the process whereby a mobile user connects to the cellular network since it is switched on, wherein cell search (CS) over the downlink and random access (RA) on the uplink are the two major steps. The highly directional communication in millimeter wave (mmWave) cellular networks requires the user and the base station (BS) to find...
Article
Ultra-densification is one of the main features of 5G networks. In an ultra-dense network, how to conduct interference management and spectrum allocation is a challenging issue. Spectrum sensing in cognitive radio networks is a distributed and efficient way to resolve this issue in ultra-dense networks. However, most of the studies on spectrum sens...
Article
Full-text available
With the promise of meeting future capacity demands, 3-D massive-MIMO/full dimension multiple-input-multiple-output (FD-MIMO) systems have gained much interest in recent years. Apart from the huge spectral efficiency gain, 3-D massive-MIMO/FD-MIMO systems can also lead to significant reduction of latency, simplified multiple access layer, and robus...
Article
Initial access is the process which allows a mobile user to first connect to a cellular network. It consists of two main steps: cell search (CS) on the downlink and random access (RA) on the uplink. Millimeter wave (mmWave) cellular systems typically must rely on directional beamforming (BF) in order to create a viable connection. The beamforming d...
Article
Coordinated Multi-Point (CoMP) transmission and reception is introduced as a promising technology in the 3GPP LTE-Advanced standard, to manage interference, improve the overall system performance, and enhance system reliability. In this paper, a resource allocation problem is studied for downlink CoMP coordinated beamforming systems where each base...
Article
To suppress the co-channel interference in a multi-cell multi-user multiple-input-multiple-output downlink cellular network, a novel interference alignment transceiver beam-forming design along with a low complexity iterative coordinated beam-forming scheme is introduced. While the latter combats the intra-cell interference, the former is utilized...
Article
Path loss models are the most fundamental part of wireless propagation channel models. Path loss is typically modelled as a (single-slope or multi-slope) power-law dependency on distance plus a log-normally distributed shadowing attenuation. Determination of the parameters of this model is usually done by fitting the model to results from measureme...