Showing papers by "Chong Han published in 2018"

Combating the Distance Problem in the Millimeter Wave and Terahertz Frequency Bands

Abstract: In the millimeter-wave (30-300 GHz) and terahertz (0.1-10 THz) frequency bands, the high spreading loss and molecular absorption often limit the signal transmission distance and coverage range. In this article, four directions to tackle the crucial problem of distance limitation are investigated, namely, a distance-aware physical layer design, ultra-massive MIMO communication, reflectarrays, and intelligent surfaces. Additionally, the potential joint design of these solutions is proposed to combine the benefits and further extend the communication distance. Qualitative and quantitative evaluations are provided to illustrate the benefits of the proposed solutions. The feasibility of mmWave and THz band communications up to 100 m in both line-of-sight and nonline- of-sight areas are demonstrated.

Propagation Modeling for Wireless Communications in the Terahertz Band

Abstract: Terahertz band (0.1-10 THz) communication is envisioned as a key technology to support ultra-broadband wireless systems for beyond 5G. For realization of efficient wireless communication networks in the THz band, it is imperative to develop channel models that can accurately and efficiently characterize the THz spectrum peculiarities. This article provides an in-depth view of channel modeling in the THz band, based on the deterministic, statistical, and hybrid methods. The state-of-the-art THz channel models in single-antenna and ultra-massive MIMO systems are extensively reviewed, respectively. Furthermore, the open challenges and potential research directions are highlighted regarding THz propagation modeling. Associated with the channel models, key physical parameters of the THz channel and their implications for wireless communication design are analyzed. The provided analysis lays the foundation for reliable and efficient ultra-broadband wireless communications in the THz band.

Ultra-Massive MIMO Channel Modeling for Graphene-Enabled Terahertz-Band Communications

Abstract: Terahertz (THz)-band communication (0.1-10 THz) is envisioned as a key wireless technology to satisfy the in- creasing demand for faster data-rates in beyond 5G systems, thanks to its ultra-broad bandwidth. The very high path loss at THz frequencies and the limited transmission power of THz transceivers impose a major distance limitation for THz wireless communications. To increase the communication distance and the achievable data rates at THz-band frequencies, the concept of Ultra-Massive MIMO (UM-MIMO) has been introduced, which integrates a very large number of nano-antennas (e.g., 1024) in very small footprints (e.g., 1 mm^2). In this paper, an end-to-end model for UM-MIMO communication in the THz band is developed, by accounting for the properties of graphene- based plasmonic nano-antenna arrays and the peculiarities of three- dimensional THz propagation. The developed model is utilized to investigate the performance of the UM- MIMO channel. In particular, the path gain, the array factor and the the wideband capacity for both spatial multiplexing and beamforming regimes are analyzed. The results show that multi-Terabit-per-second links are feasible at distances of up to 20 m when utilizing 1024 × 1024 UM-MIMO systems at 0.3 THz and 1 THz.

Hybrid Beamforming for MIMO-OFDM Terahertz Wireless Systems over Frequency Selective Channels

Abstract: We propose a novel hybrid beamforming (BF) scheme for the Terahertz (THz) wireless communication system over frequency selective channels. In the system, a multi-antenna base station which employs the sub-connected architecture adopts orthogonal frequency division multiplexing to serve a multi- antenna user. By building a wideband THz channel model, we design a beamsteering codebook searching algorithm for analog BF in which the channel state information of all subcarriers in the radio frequency domain is considered. We then design the digital BF by using the regularized channel inversion method for eliminating inter-band interference at the baseband. Numerical results demonstrate that our proposed hybrid BF scheme achieves a significant spectral efficiency advantage over the existing hybrid BF scheme which adopted the zero-forcing digital beamformer. The results also demonstrate that the spectral efficiency achieved by our proposed low-complexity scheme is very close to that achieved by the high- complexity fully digital BF scheme, especially when the average received power at the user is low.

Channel modeling and analysis for wireless networks-on-chip communications in the millimeter wave and terahertz bands

Abstract: Wireless networks-on-chip (WiNoC) are envisioned as a promising technology to support the interconnection of hundreds of cores in the chip multi-processor design To meet the demand for the Tera-bit-per-second (Tbps) ultra-fast links in the WiNoC, the millimeter wave and THz band (30 GHz-1 THz) with ultra-broad spectrum resource is proposed for WiNoC communications In this paper, a hybrid WiNoC architecture and chip design are first described Moreover, the physical models of propagations in lossy and lossless dielectric mediums are developed, by considering the realistic packaging environment A multi-path WiNoC channel model is then presented in the millimeter wave and THz band based on ray-tracing techniques, which is validated with measurement data Based on the developed channel model, the WiNoC propagation is thoroughly characterized by analyzing the time of arrival, the path gain, the coherence bandwidth, the channel capacity and the reliability Simulation results show that 1 Tbps wireless link with the error rate below 10−14 is achievable for WiNoC communications in the millimeter wave and THz band

Ieee Access Special Section Editorial: Nano-Antennas, Nano-Transceivers and Nano-Networks/Communications

Abstract: Nanotechnology is enabling the development of devices on a scale ranging from one to a few hundred nanometers. At this scale, novel nanomaterials and nanoparticles show new properties and behaviors not observed at the microscopic level. In the future, networks of nano-devices will be a key component of almost every field of our society, with applications in biomedicine, environmental protection, entertainment, homeland security, and beyond. In order to enable nano-devices to communicate with each other, many fundamental challenges need to be addressed. As the functional devices shrink into nano-scale, design, fabrication and control of the systems impose novel design principles which greatly differ from that of the macro. Electromagnetic (EM) communication in the Terahertz (THz) band (0.1–10 THz) enabled by graphene-based plasmonic nano-transceivers and nano-antennas has been suggested as one of the possible approaches for communication among these devices. This Special Section in IEEE Access is dedicated to all aspects of nanoscale communications including transceiver and antenna design in addition to communication and networking solutions, as well as novel paradigm, e.g., Hybrid Molecular/EM communication systems.

Phenomenology of Foliage Effect on 5G Millimeter-Wave V2V Communications

Abstract: Autonomous driving system and intelligent transportation systems (ITS) become increasingly popular, which requires reliable and high-speed Vehicle-to-Vehicle (V2V) communications. In realistic road traffic environment, foliage is commonly seen and blocks the line-of-sight link. In this paper, semi-exact semi-closed-form models for the far-field as well as near-field scattering from a tree trunk are developed at 5.9 and 60 GHz. Extensive numerical evaluations on the scattering fields are presented. To make the results accessible to other users, curve-fitting functions are invoked to characterize the scattered field, and are attempted to extract a macro-model for the path loss, mainly as a function of the distance and azimuth angle. This work is promisingly useful for V2V millimeter-wave communications and radar sensing.

ASMC-NOMA: Downlink Adaptive Subcarrier Spacing Multi-Carrier NOMA for 5G Time-Varying Channels

Abstract: Non-orthogonal multiple access (NOMA) scheme has been regarded as one of the promising solutions to realize a flexible and robust multiple access scheme in next generation wireless communication system. However, the inter-carrier interference caused by time-varying fading is not considered in conventional NOMA. In this paper, a novel multi-user access scheme, adaptive subcarrier-spacing multi-carrier non-orthogonal multiple access (ASMC- NOMA), is proposed to provide robust multi-user downlink transmission in time-varying channels and support user velocities up to 500 km/h. Based on the filtered-OFDM waveform, ASMC-NOMA allows flexible power-time- frequency three-dimensional resource allocation and subcarrier spacing adaptation according to the channel state and user velocities. With the user-specific adaption and coexistence of different parameters, ASMC-NOMA is able to repel the impact of high-range Doppler effects and control the signal-to-interference ratio for every downlink user. The pre-grouped resource adaptive allocation scheme is designed with the consideration of reducing the transmission overhead and receiver-end implementation complexity. Transceiver structure and signal model are discussed in detail. Theoretical analysis on the signal properties and numerical system-level simulation results prove that the proposed ASMC-NOMA effectively enhances the transmission robustness, reduces the transmission outage due to the high mobility of users, and provides increased transmission efficiency over conventional OFDM- based NOMA and multi-carrier orthogonal multiple access.

ECP: error control with probing for EM-based nanonetworks powered by energy harvesting

Abstract: Nanonetworks are comprised of nano-sized communication devices which can perform simple tasks such as computation, data storage and actuation at the nanoscale. However, due to the error-prone wireless links in the Terahertz band (0.1-10.0 THz) and very limited energy storage capacity in nanodevices, the efficient and effective error control protocols are necessary for nanonetworks. In this paper, firstly, a novel error control strategy with probing (ECP) mechanism for nanonetworks powered by energy harvesting is proposed. In particular, each data packet is transmitted only after the communication of one probing packet is successful. Secondly, the energy state model as well as state transition rate matrix by considering the energy harvesting-consumption process is presented based on the extended Markov chain approach. Thirdly, the impact of different packets energy consumption on state transition and the state probability distribution based on the above matrix are comprehensively investigated. Finally, analytical and numerical results are provided to evaluate the performance of the proposed ECP mechanism in terms of end-to-end successful packet delivery probability, end-to-end packet delay, achievable throughput and energy consumption. The results show that ECP mechanism improves the energy utilization and successful data packet delivery probability compared to ARQ schemes.