This study presents the world's fastest three-dimensional double-directional channel sounding system operating at 105 GHz with a null-to-null bandwidth of 4 GHz. The developed channel sounding system allows a full scan of the 105 GHz multipath channel in both azimuth and elevation angles of the transmitter (TX) and receiver (RX) directional antennas. The developed channel sounding system is calibrated with an anechoic measurement in that the path loss of the observed line-of-sight ray coincides with the free-space path loss. Moreover, the anechoic measurement verifies the performance of the channel sounding system, where the delay resolution is lower than 0.5 ns, and the angular resolution is approximately 10° in the azimuth plane for both TX and RX.

This study presents wideband propagation measurements of 105 GHz multipath characteristics, encompassing a full 360°in a real office desktop environment. High-speed wireless personal area network (WPAN) systems operating in such environments represent a promising use case for sub-terahertz (THz) communication systems owing to the short-range nature of such networks. Additionally, selecting a frequency band close to the millimeter-wave spectrum increases the feasibility of sub-THz WPAN systems compared to the widely recognized 300 GHz band, mainly because of the availability of low-cost hardware. However, the multipath propagation characteristics at the 105 GHz band, specifically within a 360° range in a real office desktop environment, have not been thoroughly investigated. To address this gap, we evaluate the 105 GHz multipath propagation characteristics, considering both delay and angular profiles, and compare them with our concurrent 60 GHz measurements in the same environment. The results indicate a notable distinction between the two bands: a physical partition maintaining personal space causes the multipath power at 105 GHz to deviate by 10 dB relative to the 60 GHz band. Furthermore, our system-oriented analysis highlights the similarity of propagation characteristics in both bands, as nearly all multipath waves at 105 GHz exhibit power levels comparable to those observed at 60 GHz. In both frequency bands, the delay spread extends up to 5 ns, while the angular spread reaches up to 40°. These findings suggest that the current 60 GHz WPAN system standards could be effectively extended to the 105 GHz band for sub-THz WPAN applications.

To meet increasing demands for higher-rate communication, exploring the sub-terahertz (THz) band is attracting huge attention. The first standardization of a sub-THz communication was performed at the IEEE 802.15.3d task group, which designed an ultra-wideband short-range communication operating in a 300 GHz band. However, to alleviate hardware challenges, the usage of a much lower-sub-THz band, that is around 100 GHz, should also be considered. Moreover, in terms of the advantage of using signal processing circuits common to 5G new radio (NR), the frame format should be designed in a compatible manner with the commercially pervasive 5G NR, which cannot be reached by IEEE 802.15.3d. Motivated by these backgrounds, this paper proposes a 5G NR-based ultra-wideband short-range communication operating in a low sub-THz band that lies in 90–110 GHz. This can be achieved by using 5G NR sidelink communication with the bandwidth expansion to several GHz, and no changes are made for the frame format to retain compatibility. This study conducts a performance evaluation of such a 5G NR sidelink system with a 4 GHz bandwidth by using a recently developed channel model at the 93–97 GHz band. The evaluation reveals that the proposed communication system using the 5G NR sidelink can achieve a block error rate (BLER) equal to 0.1 for both control and user-data transmissions even when a 4 GHz bandwidth is utilized. Moreover, it is shown that transmission at a meter-level distance is feasible even when an omnidirectional antenna in an azimuth plane is used.

Millimeter wave (mmWave) commutation standards in the unlicensed band, including IEEE 802-led wireless personal area network (WPAN), wireless local area network (WLAN), and 3GPP-led cellular network (CN), have been facing challenges for over ten years to acquire commercial acceptance. Towards widespread mmWave communication systems supporting the 6G connectivity, an innovation concept called mmWave virtual community network (VCN) has been proposed recently, where decentralized WPAN-type device-to-device (D2D) community coexists with centralized WLANs/CNs in the unlicensed mmWave band via multihop links without full use of high-gain beamforming. Based on this concept, this paper further proposes a strategic ecosystem to spur mmWave VCN deployment with the mutual benefit of decentralized and centralized entities. Therein, a decentralized community via mmWave D2D communication helps coverage area expansion of mmWave WLAN/CN while the CN operator incentivizes the distributed communities to expand themselves with a reward mechanism to ensure mutual benefits. To drive the proposed ecosystem, we propose a new radio sidelink mmWave unlicensed (NR SL-mmW-U) as a decentralized D2D communication framework in detail including an initial physical (PHY) layer specification, such as subchannel size and slot format. We holistically evaluate the proposed NR SL-mmW-U for both control and user data transmissions based on the latest stochastic 60 GHz channel model tailored for D2D communication and 60 GHz-specific hardware impairment models. The evaluation demonstrates the feasibility of NR SL-mmW-U fulfilling the key requirement for deriving the proposed ecosystem, where the transmission distance of 1-10 m is achievable without high-gain beamforming antennas for all types of examined data and channel environments.

This paper comprehensively presents 105 GHz multipath characterizations for indoor short-range communication environments and proposes a stochastic channel generator compatible with the third-generation project partnership (3GPP) standard. Using extensive wideband propagation measurements, we holistically derive the statistical distributions of both largescale parameters (LSPs) and small-scale parameters for various indoor short-range communication environments, such as desktops in conference rooms, corridors, and office rooms. These distributions not only capture the holistic propagation characteristics of this underexplored frequency band in the aforementioned environments but also serve as a complete stochastic model sufficient for developing a multipath channel generator to perform physical layer link-level simulations. The derived parameters are compared with those specified in the incumbent 3GPP stochastic channel model for an indoor hotspot office scenario, highlighting the fact that the cross-correlation between the azimuth angle spread of arrival and the K-factor demonstrates a major difference, requiring model amendments for short-range use cases in this band. Based on these results, we propose a 3GPP-compatible channel generation algorithm tailored for all three indoor short-range communication scenarios at 105 GHz, incorporating the derived statistical distributions. The extensive simulations of channel generation demonstrated consistency with our propagation measurements in terms of intra-cluster subpath characteristics and LSPs, demonstrating the validity of the proposed channel generation algorithm. Our results offer a foundation for accurate link-level simulations in various 105 GHz short-range communication use cases, which is crucial for advancing next-generation wireless communication systems. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.

This paper proposes a comprehensive 3GPPcnaompatible channel model with statistical enhancement tailored for indoor short-range device-to-device (D2D) communications operating in the frequency range (FR) of 52.6-71.0 GHz termed FR2-2. Regardless of the existence of various channel models at this band for indoor communications, there will be a need for developing a channel model compatible with and understandable from the current 3GPP stochastic channel model (SCM) to facilitate the discussion in the 3GPP for developing such FR2-2 short-range D2D communication framework based on the fifthgeneration (5G) new radio (NR). Indeed, such a futuristic vision can be foreseen from the fact that the 3GPP is discussing the evolution of sidelink, referred to as a D2D communication framework; however, there are no 3GPP SCM-compatible channel models applicable to FR2-2 short-range D2D communications. To fill this void, we propose the channel model coined 3GPPCompFR2-InS that allows us to generate channel impulse responses (CIR) for computer simulations, which is suitable for various indoor short-range D2D communication scenarios while retailing the similarity in terms of the implementation policy of the 3GPP SCM. 3GPPCompFR2-InS is verified based on the real-world measurements at the 60 GHz band from the viewpoint of both the validity of the channel model parameters and that of the statistical behavior of the generated CIRs.This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible

This study presents a 95 GHz indoor channel measurement campaign for a short-range communication scenario and proposes an improved intra-cluster stochastic channel generation procedure compatible with the well-known 3GPP stochastic channel model (SCM). The current 3GPP SCM casts itself to apply to the frequency range up to 100 GHz; however, there is no measurement-based validation for this upper limit because of the lack of measurement campaign for 90 GHz–100 GHz. Moreover, the 3GPP SCM generates the characteristics of intra-cluster subpath parameters equally to all clusters in terms of the number of clusters and per-cluster delay spread, falling short of capturing real channel characteristics, particularly for the usage of large bandwidth. Motivated by the first limitation, we holistically derive the statistical parameters of the 95 GHz channel propagation characteristics in a simple conference room scenario and compare these parameters with our 60 GHz channel measurement results in a similar environment. This investigation confirms the feasibility of the 60 GHz statistical parameters generalized for the 95 GHz band at least in the measured scenario. Moreover, to solve the second issue, we propose an unequal intra-cluster subpath generation procedure, serving as a 3GPPcompatible amendment for accurate channel generation. Numerical evaluation reveals the feasibility of generating channel impulse responses capturing more accurate intra-cluster subpath characteristics than the current 3GPP SCM.

This study analyzes the omnidirectional power delay profile (PDP) characteristics at the 105 GHz band in a personal office desktop area by conducting a multipath propagation measurement. In those days, for the 6th generation communication system, there is a demand for a wider bandwidth, and exploring sub-terahertz (sub-THz) is attracting huge interest. However, the omnidirectional multipath propagation characteristics at the 105 GHz band, which is a part of sub-THz band, for a personal desktop environment has not been investigated yet regardless of the potential feasibility of the wireless personal area network (WPAN) communication systems operating at this band in a personal desktop area. In this study, we first conduct a measurement of omnidirectional PDPs for the 105 GHz and 60 GHz bands in a personal desktop environment. The comparison of these two bands unveils an affinity in terms of delay-domain multipath characteristics, where the delay spread difference is less than 1 ns. Moreover, this study derives an appropriate guard interval (GI) length to be 20 ns at most for the personal desktop environment, which is compared with those in the internationally standardized 60 GHz wireless personal area network (WPAN) communication systems. These two comparisons with 60 GHz bands provide evidence for the feasibility of 105 GHz wideband WPAN communication systems, which can be designed analogously from 60 GHz WPAN communication systems. This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.

Sidelink communication has evolved as a distributed device-to-device (D2D) communication system within the third-generation partnership project (3GPP) for the advancements in next-generation distributed autonomous systems. However, the current sidelink communication system basically being considered for operation at microwave band is not suitable for distributed wireless networking with a Gbit/s-level data rate. In this context, we have conceptualized a millimeter wave (mmWave) sidelink-based wireless personal area network (WPAN) to enable high-speed distributed wireless networking among indoor proximate devices. Particularly, inspired by the notion of "common-mode signaling (CMS)" in the IEEE 802.15.3c/11ad mmWave WPAN standards, we proposed an innovative physical sidelink broadcast channel (PSBCH) coined CMS-PSBCH to reach a robust inter-node control signaling to maintain a connection under harsh mmWave channel characteristics. As a sequential study, this paper proposes a robust signal detection and timing synchronization scheme tailored for CMS-PSBCH to lead a successful detection and demodulation, thereby providing a complete set of robust synchronization signal block (SSB) for the sidelink-based mmWave WPAN. Our linklevel evaluation shows that the proposed scheme effectively detects synchronization signals and symbol timing even under the signalto-noise ratio (SNR) of-18 dB. Moreover, the proposed scheme leads to successful demodulation of CMS-PSBCH payload for various multipath channels for a wideband indoor short-range communication scenario at the 60 GHz band.This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible

This paper presents a comprehensive wideband indoor propagation characterization via real-world experiments at 105.8 GHz with a 4 GHz bandwidth in a lecture hall environment. Utilizing a double-directional channel sounding system with rotating horn antennas, we measure power angular delay profiles (PADPs) at multiple receiver (RX) positions. Our study derives a path loss model, delay characteristics, and angle characteristics, including path loss exponent, root mean square (RMS) delay spread (DS), K-factor, RMS azimuth angle spread of arrival (ASA), and RMS azimuth angle spread of departure (ASD). We compared these results with the 3GPP indoor hotspot (InH) office model (up to 100 GHz), highlighting both similarities and differences in propagation characteristics. Notably, the path loss exponent was found to be 1.38, which is lower than the 1.73 observed in the 3GPP InH-Office LoS model. Moreover, there were positive correlations between the above spread values and transmitter (TX)-RX distance, and negative correlations between K-factor and TX-RX distance, which were not considered in the 3GPP InH-Office LoS model. Furthermore, our analysis revealed a strong negative correlation in RMS ASA vs K-factor and RMS ASD vs K-factor, which are not accounted for in the current 3GPP InH office model. These findings emphasize the need to consider such correlations in accurate propagation models in lecture hall scenarios at the 105 GHz sub-THz band.This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible

With advancements in distributed autonomous systems (e.g., vehicles, sensors, and robots) in the 5G/6G era, sidelink communication technology has evolved as a distributed communication system in the third-generation partnership project (3GPP). However, the current sidelink communication design focusing on information dissemination or point-to-point communication with a low rate is not suitable for rapid development of such autonomous systems. Instead, based on sidelink, developing distributed wireless personal area networks (WPANs) with a drastically higher rate for transmitting user data is essential. The overarching goal of this study is to explore the possibility of sidelink communication evolution to 1) form a distributed and autonomous WPAN and 2) support millimeter wave (mmWave) bands. Our core idea is to merge several design concepts of the precedented mmWave WPAN standards, i.e., IEEE 802.15.3c/11ad, into the sidelink communications, thereby bridging the gap between the two separated systems. This paper presents the anatomy of the IEEE 802.15.3c/11ad system with a focus on the formation of mmWave WPANs among distributed nodes and their operation. In addition, the current status of sidelink communication system design is highlighted, along with the missing building blocks, which are required to develop 3GPP sidelink-based mmWave WPAN systems. Simulation results shed light on merging IEEE 802.15.3c/11ad concepts into 3GPP sidelink communication regarding a control data transmission scheme, which should be designed to enhance robustness and is a crucial step for subsequent high-rate user data transmission.This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible.

This study aims to provide a unified view of the various standard millimeter-wave (mmWave) channel modeling frameworks for mmWave wireless deployments in sixth-generation (6G) wireless networks, focusing on wireless personal area networks (WPAN), wireless local area networks (WLAN), and cellular networks (CN). The 6G era will witness the emergence of security-sensitive, more mission-critical, and data-intensive applications, wherein massive amount of data will be exchanged while satisfying the stringent requirements for latency, reliability, trustworthiness, and data rate. Thus, mmWave connectivity has been considered and would result in the co-existence of decentralized networks and centralized CNs, eventually blurring the distinction between WPANs, WLANs, and CNs. Motivated by this futuristic vision, we first reviewed the present status of the standard channel models for WPAN, WLAN, and CNs to understand the common characteristics of mmWave channel models therein. We show that despite their differences in sight- specificity levels and employed mathematical functions, all standard channel models target the generation of a commonly structured channel impulse response comprising eight shared components. Furthermore, based on the affinity, we propose a research direction to develop unified mmWave channel generation for WPAN, WLAN, and CN, where channel simulations for the three scenarios can be conducted in an identical framework. Our experimental results shed light on the feasibility of the proposed research direction and highlight the challenges and opportunities.This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessible