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1. Ray Tracing Analysis for UAV-Assisted Integrated Access and Backhaul Millimeter Wave Networks

   https://doi.org/10.1109/WoWMoM.2019.8792969  

   Perez, Alberto; Fouda, Abdurrahman; Ibrahim, Ahmed S. (June 2019, 2019 IEEE 20th International Symposium on "A World of Wireless, Mobile and Multimedia Networks" (WoWMoM))

   The use of Millimeter-wave (mmWave) spectrum in cellular communications has recently attracted growing interest to support the expected massive increase in traffic demands. However, the high path-loss at mmWave frequencies poses severe challenges. In this paper, we analyze the potential coverage gains of using unmanned aerial vehicles (UAVs), as hovering relays, in integrated access and backhaul (IAB) mmWave cellular scenarios. Specifically, we utilize the WinProp software package, which employs ray tracing methodology, to study the propagation characteristics of outdoor mmWave channels at 30 and 60 GHz frequency bands in a Manhattan-like environment. In doing so, we propose the implementation of amplify-and-forward (AF) and decode-and-forward (DF) relaying mechanisms in the WinProp software. We show how the 3D deployment of UAVs can be defined based on the coverage ray tracing maps at access and backhaul links. Furthermore, we propose an adaptive UAV transmission power for the AF relaying. We demonstrate, with the aid of ray tracing simulations, the performance gains of the proposed relaying modes in terms of downlink coverage, and the received signal to interference and noise ratio (SINR). 

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2. Performance study of statistical and deterministic channel models for mmWave wi-fi networks in ns-3

   https://doi.org/10.1145/3460797.3460802  

   Liu, Yuchen; Crisp, Shelby K.; Blough, Douglas M. (May 2021, Proceedings of the Workshop on ns-3)

   null (Ed.)

   To address the needs of emerging bandwidth-intensive applications in 5G and beyond era, the millimeter-wave (mmWave) band with very large spectrum availability have been recognized as a promising choice for future wireless communications. In particular, IEEE 802.11ad/ay operating on 60 GHz carrier frequency is a highly anticipated wireless local area network (WLAN) technology for supporting ultra-high-rate data transmissions. In this paper, we describe additions to the ns-3 802.11ad simulator that include 3D obstacle specifications, line-of-sight calculations, and a sparse cluster-based channel model, which allow researchers to study complex mmWave Wi-Fi network deployments under more realistic conditions. We also study the performance accuracy and simulation efficiency of the implemented statistical channel model as compared to a deterministic ray-tracing based channel model. Through extensive ns-3 simulations, the results show that the implemented channel model has the potential to achieve good accuracy in performance evaluation while improving simulation efficiency. We also provide a detailed parametric analysis on the statistical channel model, which yields insight on how to properly tune the model parameters to further improve performance accuracy. 

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3. A mmWaves Channel Sounding Technique to Capture Human-induced Dynamic Multipaths

   https://doi.org/10.46620/URSIATRASC24/ZOQS9914  

   Alesii, Roberto; Cassioli, Dajana; Molisch, Andreas (January 2024, URSI – International Union of Radio Science)

   Design and standardization of future millimeter-wave (mmWave) wireless communications systems require accurate models of wireless propagation channels. In particular, comprehensive statistical models describing the effect of human bodies moving randomly in the surrounding environment, acting as reflectors or absorbers, on the received power and delay spread are urgently needed. To enable these, new measurements campaigns are required based on channel sounders designed specifically to capture the realtime dynamics of the channel responses. This paper proposes a new methodology to enable fully dynamic measurements with a pseudonoise (PN)-sequence channel sounder by means of quasi-perfect transmitter-receiver (Tx-Rx) synchronization and suppression of probing signal effects in the post-processed channel impulse responses (CIRs). This approach allows the identification of the weak multipath components (MPCs) originated by reflections on the human body. The approach is validated by analysing CIRs collected in an indoor environment with one person moving close to the 60 GHz link. The results also demonstrate that future mmWave systems could exploit these additional MPCs and benefit from human interactions. 

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4. IEEE 802.11ay based mmWave WLANs: Design Challenges and Solutions

   https://doi.org/10.1109/COMST.2018.2816920  

   Zhou, Pei; Cheng, Kaijun; Han, Xiao; Fang, Xuming; Fang, Yuguang; He, Rong; Long, Yan; Liu, Yanping (January 2018, IEEE Communications Surveys & Tutorials)

   Millimeter-wave (mmWave) with large spectrum available is considered as the most promising frequency band for future wireless communications. The IEEE 802.11ad and IEEE 802.11ay operating on 60 GHz mmWave are the two most expected wireless local area network (WLAN) technologies for ultra-high-speed communications. For the IEEE 802.11ay standard still under development, there are plenty of proposals from companies and researchers who are involved with the IEEE 802.11ay task group. In this survey, we conduct a comprehensive review on the medium access control layer (MAC) related issues for the IEEE 802.11ay, some cross-layer between physical layer (PHY) and MAC technologies are also included. We start with MAC related technologies in the IEEE 802.11ad and discuss design challenges on mmWave communications, leading to some MAC related technologies for the IEEE 802.11ay. We then elaborate on important design issues for IEEE 802.11ay. Specifically, we review the channel bonding and aggregation for the IEEE 802.11ay, and point out the major differences between the two technologies. Then, we describe channel access and channel allocation in the IEEE 802.11ay, including spatial sharing and interference mitigation technologies. After that, we present an in-depth survey on beamforming training (BFT), beam tracking, single-user multiple-input-multiple-output (SU-MIMO) beamforming and multi-user multiple-input-multiple-output (MU-MIMO) beamforming. Finally, we discuss some open design issues and future research directions for mmWave WLANs. We hope that this paper provides a good introduction to this exciting research area for future wireless systems. 

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5. Outdoor mmWave Channel Propagation Models using Clustering Algorithms

   https://doi.org/10.1109/ICNC47757.2020.9049734  

   Antonescu, B.; Tehrani-Moayyed, M.; Basagni, S. (April 2020, 2020 International Conference on Computing, Networking and Communications (ICNC): Wireless Communications)

   This paper concerns the task of generating simpler yet accurate mmWave channel models based on clustering all multipath components arriving at the receiver. Our work focuses on 28 GHz communications in urban outdoor scenarios simulated with a ray-tracer tool. We investigate the effectiveness of k- means and k-power-means clustering algorithms in predicting the optimal number of clusters by using cluster validity indices (CVIs) and score fusion techniques. Our results show how the joint use of these techniques generate accurate approximation of the mmWave large-scale and small-scale channel models, greatly simplifying the complexity of analyzing large amount of rays at any receiver location. 

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