Sub-Terahertz Channel Sounder: Review and Future Challenges

Due to the large amount of unused and unexplored spectrum resources, the so-called subTerahertz(sub-THz) frequency bands from 100 to 300 GHz are seen as promising bands for the next generation of wireless communication systems. Channel modeling at sub-THz bands is essential for the design and deployment of future wireless communication systems. Channel measurement is a widely adopted method to obtain channel characteristics and establish mathematical channel models. Channel measurements depend on the design and construction of channel sounders. Thus, reliable channel sounding techniques and accurate channel measurements are required. In this paper, the requirements of an ideal channel sounder are discussed and the main channel sounding techniques are described for the subTHz frequency bands. The state-of-the-art sub-THz channel sounders reported in the literature and respective channel measurements are presented. Moreover, a vector network analyzer(VNA) based channel sounder, which supports frequency bands from 220 to330 GHz is presented and its performance capability and limitation are evaluated. This paper also discussed the challenge and future outlook of the sub-THz channel sounders and measurements.

Measurement-Based Channel Characterization in a Large Hall Scenario at 300 GHz

Sub-terahertz(Sub-THz),defined as the frequency bands in 100-300 GHz,is promising for future generation communications and sensing applications.Accurate channel measurement and modeling are essential for development and performance evaluation of the future communication systems.Accurate channel modeling relies on realistic channel data,which should be collected by high-fidelity channel sounder.This paper presents the measurement-based channel characterization in a large indoor scenario at 299-301 GHz.We firstly review the state-of-the-art channel measurements at sub-THz frequency bands.We then presented a VNA-based channel sounder for long-range measurements,which uses the radio-overfiber techniques.Channel measurements using this channel sounder are conducted in a large hall scenario.Based on the measurement data,we calculated and analyzed key propagation channel parameters,e.g.,path loss,delay spread,and angular spread.The results are also analyzed both in the line-of-sight(Lo S)and noneLo S(NLo S)cases.The large delay components in the measurements demonstrate the possibility of the longrange channel measurement campaign at 300 GHz.

Long-Range VNA-Based Channel Sounder: Design and Measurement Validation at MmWave and Sub-THz Frequency Bands

With the increasing demand for high bandwidth wireless communication systems,and with a congested spectrum in the sub-6 GHz frequency bands,researchers have been looking into exploration of millimeter wave(mmWave)and sub-terahertz(subTHz)frequency bands.Channel modeling is essential for system design and performance evaluation of new wireless communication systems.Accurate channel modeling relies on reliable measured channel data,which is collected by high-fidelity channel sounders.Furthermore,it is of importance to understand to which extent channel parameters are frequency dependent in typical deployment scenario(including both indoor short-range and outdoor long-range scenarios).To achieve this purpose,this paper presents a stateof-art long-range 28 GHz and 300 GHz VNA-based channel sounder using optical cable solutions,which can support a measurement range up to 300 m and 600 m in principle,respectively.The design,development and validation of the long-range channel sounders at mmWave and sub-THz bands are reported,with a focus on their system principle,link budget,and backto-back measurements.Furthermore,a measurement campaign in an indoor corridor is performed using the developed 300 GHz system and 28 GHz channel sounding systems.Both measured channels at the 28 GHz and 300 GHz channels are shown to be highly sparse and specular.A higher number of Multi Path Components(MPC)are observed for the 28 GHz system,while the same main MPC are observed for both systems.