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Millimeter-Wave (mmWave) (30-300 GHz) and D band (110-170 GHz) frequencies are poised to play a pivotal role in the advancement of sixth-generation (6G) systems and beyond with increased demand for greater bandwidth and capacity. This paper focuses on deriving a generalized channel impulse response for mmWave communications, considering both outdoor and indoor locations for line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. The analysis is based on statistical insights obtained from measurements conducted at distinct locations with a center frequency of 142 GHz, examining parameters such as path gain, delay, number of paths (NoP), and angle distributions. Whereas different distributions serve as candidate models for the gain of LOS communications, only specific distributions accurately describe the NLOS gain, LOS and NLOS delay, LOS and NLOS NoP, and LOS and NLOS angular distributions. The channel is modeled based on geometry-based stochastic channel modeling (GBSM) with parameters derived from the statistical analysis. The maximum excess delay is used as a metric to evaluate the performance of the proposed model against empirical data., Comment: arXiv admin note: text overlap with arXiv:2403.18713

Millimeter-wave (mmWave) and D Band (110--170~GHz) frequencies are poised to play a pivotal role in the advancement of sixth-generation (6G) systems and beyond, owing to their ability to enhance performance metrics such as capacity, ultra-low latency, and spectral efficiency. This paper concentrates on deriving statistical insights into power, delay, and the number of paths based on measurements conducted across four distinct locations at a center frequency of 143.1 GHz. The findings underscore the suitability of various distributions in characterizing power behavior in line-of-sight (LOS) scenarios, including lognormal, Nakagami, gamma, and beta distributions, whereas the loglogistic distribution gives the optimal fit for power distribution in non-line-of-sight (NLOS) scenarios. Moreover, the exponential distribution shows to be the most appropriate model for the delay distribution in both LOS and NLOS scenarios. In terms of the number of paths, observations indicate a tendency for the highest concentration within the 10 m to 30 m distance range between the transmitter (Tx) and receiver (Rx). These insights shed light on the statistical nature of D band propagation characteristics, which are vital for informing the design and optimization of future 6G communication systems, Comment: 6 pages, 22 figures

In this paper, we present new measurement results to model large-scale path loss, angular spread and channel sparsity at the sub-THz (141-145 GHz) band, for both indoor and outdoor scenarios. Extensive measurement campaigns have been carried out, taking into account both line-of-sight (LoS) and non line-of-sight (NLoS) propagation. For all considered propagation scenarios, omni-directional and directional path loss models have been developed, based on the so-called close-in (CI) free-space reference distance model. Moreover, path loss modeling has been applied for the 2nd and 3rd strongest multipath components (MPCs), based on which path loss exponent and large-scale shadow fading estimates have been derived. A power angular spread analysis is further presented, using up to the 3rd strongest MPC. Finally, results on the sparsity of the wireless channel have also been presented by employing the so-called Gini index.

6G will likely be the first generation of mobile communication that will feature tight integration of localization and sensing with communication functionalities. Among several worldwide initiatives, the Hexa-X flagship project stands out as it brings together 25 key players from adjacent industries and academia, and has among its explicit goals to research fundamentally new radio access technologies and high-resolution localization and sensing. Such features will not only enable novel use cases requiring extreme localization performance, but also provide a means to support and improve communication functionalities. This paper provides an overview of the Hexa-X vision alongside the envisioned use cases. To close the required performance gap of these use cases with respect to 5G, several technical enablers will be discussed, together with the associated research challenges for the coming years.