recent research results

Research Results from NSF Grant 1909206

We presented recent global spectrum regulations as well as fundamental atmospheric and rain attenuation considerations at frequencies above 100 GHz in [1], which shows there is no fundamental physical channel impediment for utilizing sub-THz and THz bands up to 1 THz for future wireless communications. We conducted extensive radio propagation measurements in both indoor hotspot (InH) office [2,3] and outdoor urban microcell (UMi) environments [5]. Both the indoor and outdoor measurements showed that there was a remarkable similarity in terms of path loss exponents over 28, 73, and 142 GHz for both LOS and NLOS scenarios, when referenced to the first meter free-space reference distance. According to the measurements, the d0 = 1 m close-in (CI) free space reference distance path loss model is more sensible for a universal standard for comparing path loss among different frequencies, locations, and researchers [2, 3, 5]. We developed a statistical channel model for an indoor office building using the 28 GHz and 142 GHz measurement data, which shows that the 142 GHz channel is much sparser than the 28 GHz channel with a much smaller delay spread and angular spread [3,4]. We also characterized the 28 GHz mmWave vehicle-to-infrastructure (V2I) channel in collaboration with AT&T, and determined the optimal beam switching rate to maximize UE throughput [6].

The 3rd Generation Partnership Project (3GPP) included the indoor factory (InF) environments as a scenario of interest since Release 15. In 2021-22, we conducted channel propagation measurements including the use of passive reflective intelligent surfaces (RIS) inside 4 factory buildings to support the 3GPP InF channel modeling efforts. The initial results in [20] indicate a rich-scattering environment due to a massive number of metal structures and objects, which can facilitate emerging sub-THz applications such as super-resolution sensing and positioning for future smart factories.

The channel model derived from the data collected at 28 GHz and 142 GHz was used to develop NYUSIM, an open-source channel simulator, which has been downloaded over one hundred thousand times by industry and academia. Additionally, NYURay, a mmWave and sub-THz ray tracer with material properties and propagation characteristics calibrated to real-world measurements has been developed [7], which shall be released for use to the wireless research community soon.

Results of the propagation measurements were shared with Tufts University (Prof. Mail Vu’s team), as well as with the Millimeter Wave Coalition and the NYU WIRELESS Industrial Affiliates companies. Extensive results were given in over three dozen invited talks during the COVID era by PI Rappaport.

We successfully miniaturized the channel sounder baseband by developing and interfacing an evaluation board with a 2 GHz RF bandwidth channel sounder IC [8,9]. MAP-AT, a mmWave position location algorithm developed by our group was tested on indoor and outdoor data at 28 and 142 GHz, and was shown to achieve decimeter-level position location accuracy [7,10,11,18]. Additionally, the performance of position location using 5G signaling with bistatic radar was studied in collaboration with InterDigital, wherein the optimal wireless node locations were determined via geometric dilution of precision (GDOP) [12]. Work done in collaboration with Nokia studied non-terrestrial networks (e.g., satellites and high altitude platform stations (HAPS)) and showed that one HAPS can provide a coverage area with a radius of 100 km, and using a repeater-based architecture on a HAPS is more power-efficient [13]. Another collaboration with Nokia Bell Labs studies the outdoor-to-indoor coverage for mmWave cellular deployments and estimated 15% indoor users would experience outage at 28 GHz [19].

The master’s thesis by Dipankar Shakya, based on the miniaturization work was awarded the “Theodor Tamir award for Best Master’s Thesis” by NYU. Shihao Ju’s recent work on the MIMO channel modeling at 142 GHz for urban microcells received the Best Paper Award in the 2021 IEEE Global Communication Conference (GLOBECOM) [14].

In addition to the aforementioned works, a pioneering mathematical framework for quantifying and comparing power consumption – something vital for proper wireless network design that will help conserve greenhouse gas emissions and improve our planet in the era of climate change, was developed in this project. Breakthrough figures of merit called the Power Waste Factor (W), and Consumption Efficiency Factor (CEF), were perfected and published in the Dec. 2022 IEEE Wireless Communciations Magazine [17], and were used to study a High Altitude Platform System (HAPS) with Nokia earlier in the project.

[1] Y. Xing and T. S. Rappaport, “Terahertz Wireless Communications: Co-Sharing for Terrestrial and Satellite Systems Above 100 GHz,” in IEEE Communications Letters, vol. 25, no. 10, pp. 3156-3160, Oct. 2021. https://ieeexplore.ieee.org/document/9450810

[2] Y. Xing, T. S. Rappaport, and A. Ghosh, “Millimeter Wave and Sub-THz Indoor Radio Propagation Channel Measurements, Models, and Comparisons in an Office Environment,” in IEEE Communications Letters, vol. 25, no. 10, pp. 3151-3155, Oct. 2021. https://ieeexplore.ieee.org/document/9450830

[3] S. Ju, Y. Xing, O. Kanhere and T. S. Rappaport, “Millimeter-Wave and Sub-Terahertz Spatial Statistical Channel Model for an Indoor Office Building,” in IEEE Journal on Selected Areas in Communications, vol. 39, no. 6, pp. 1561-1575, June 2021. https://ieeexplore.ieee.org/abstract/document/9411894

[4] S. Ju and T. S. Rappaport, “140 GHz Urban Microcell Propagation Measurements for Spatial Consistency Modeling,” 2021 IEEE International Conference on Communications (ICC), Jun. 2021, pp. 1-6. https://arxiv.org/abs/2103.05496

[5] Y. Xing and T. S. Rappaport, “Millimeter Wave and Terahertz Urban Microcell Propagation Measurements and Models,” in IEEE Communications Letters, vol. 25, no. 12, pp. 3755-3759, Dec. 2021, doi: 10.1109/LCOMM.2021.3117900. https://ieeexplore.ieee.org/document/9558848

[6] O. Kanhere, A. Chopra, A. Thornburg, T. S. Rappaport, and S. S. Ghassemzadeh “Performance Impact Analysis of Beam Switching in Millimeter Wave Vehicular Communications,” 2021 IEEE 93rd Vehicular Technology Conference (VTC-Spring), April 2021, pp. 1-7. https://arxiv.org/abs/2103.03434

[7] O. Kanhere and T. S. Rappaport, “Millimeter Wave Position Location using Multipath Differentiation for 3GPP using Field Measurements,” in GLOBECOM 2020 – 2020 IEEE Global Communications Conference, Taipei, Taiwan, Dec. 2020, pp. 1–7. https://arxiv.org/abs/2009.10202

[8] D. Shakya, T. Wu, M. E. Knox and T. S. Rappaport, “A Wideband Sliding Correlation Channel Sounder in 65 nm CMOS: Evaluation Board Performance,” in IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 68, no. 9, pp. 3043-3047, Sept. 2021. https://arxiv.org/abs/2106.06855

[9] D. Shakya, T. Wu and T. S. Rappaport, “A Wideband Sliding Correlator based Channel Sounder in 65 nm CMOS: An Evaluation Board Design,” GLOBECOM 2020 – 2020 IEEE Global Communications Conference, 2020, pp. 1-6. https://arxiv.org/abs/2009.13490

[10] O. Kanhere and T. S. Rappaport, “Outdoor sub-THz Position Location and Tracking using Field Measurements at 142 GHz,” in 2021 IEEE International Conference on Communications (ICC), June 2021, pp. 1–6. https://arxiv.org/abs/2103.05219

[11] O. Kanhere and T. S. Rappaport, “Position Location for Futuristic Cellular Communications – 5G and Beyond,” in IEEE Communications Magazine, vol. 59, no. 1, pp. 70-75, January 2021. https://arxiv.org/abs/2102.12074

[12] O. Kanhere, S. Goyal, M. Beluri, and T. S. Rappaport, “Target Localization using Bistatic and Multistatic Radar with 5G NR Waveform,” 2021 IEEE 93rd Vehicular Technology Conference (VTC-Spring), April 2021, pp. 1-7. https://arxiv.org/abs/2103.034263

[13] Y. Xing, F. Hsieh, A. Ghosh, and T. S. Rappaport, “High Altitude Platform Stations (HAPS): Architecture and System Performance,” 2021 IEEE 93rd Vehicular Technology Conference (VTC-Spring), April 2021, pp. 1-6. https://arxiv.org/abs/2103.03431

[14] S. Ju and T. S. Rappaport, “Sub-Terahertz Spatial Statistical MIMO Channel Model for Urban Microcells at 142 GHz,” 2021 IEEE Global Communications Conference (GLOBECOM), Dec. 2021, pp. 1-6. https://arxiv.org/abs/2110.06361

[15] A. Alizadeh, M. Vu and T. S. Rappaport, “A Study of Interference Distributions in Millimeter Wave Cellular Networks,” 2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems (COMCAS), Tel-Aviv, Israel, Nov. 2019, pp. 1-6. https://arxiv.org/abs/1911.05599

[16] S. Ju, Y. Xing, O. Kanhere, and T. S. Rappaport. “3-D Statistical Indoor Channel Model for Millimeter-Wave and Sub-Terahertz Bands,” 2020 IEEE Global Communications conference (GLOBECOM),Taipei, Taiwan, Dec. 2020, pp 1-7. https://arxiv.org/abs/2009.12971

[17] O. Kanhere, H. Poddar, Y. Xing, D. Shakya, S. Ju and T. S. Rappaport, “A Power Efficiency Metric for Comparing Energy Consumption in Future Wireless Networks in the Millimeter Wave and Terahertz bands,” in IEEE Wireless Communications. https://ieeexplore.ieee.org/document/9864328

[18] Kanhere, O. and Rappaport, T.S. “Outdoor sub-THz Position Location and Tracking using Field Measurements at 142 GHz” 2021 IEEE International Conference on Communications (ICC), June 2021. https://ieeexplore.ieee.org/document/9838910

[19] Shakya, Dipankar and Chizhik, Dmitry and Du, Jinfeng and Valenzuela, Reinaldo A. and Rappaport, Theodore S. “Dense Urban Outdoor-Indoor Coverage from 3.5 to 28 GHz” 2022 IEEE International Conference on Communications, 2022. https://ieeexplore.ieee.org/document/9838919

[20] Ju. S. and Xing, Y. and Kanhere O. and and Rappaport, T.S. “Sub-Terahertz Channel Measurements and Characterization in a Factory Building,” pp. 1-6. 2022 IEEE International Conference on Communications (ICC), May, 2022. https://ieeexplore.ieee.org/document/9838910

[21] Lota, Jaswinder and Ju, Shihao and Kanhere, Ojas and Rappaport, Theodore S. and Demosthenous, Andreas “mmWave V2V Localization in MU-MIMO Hybrid Beamforming” IEEE Open Journal of Vehicular Technology , v.3 , 2022. https://ieeexplore.ieee.org/document/9763561