Characteristics and modeling of UAV-vehicle MIMO wideband channels

A geometry-based stochastic model(GBSM) for unmanned aerial vehicle to vehicle(UAV-V) multiple-input multiple-output(MIMO) wideband channel is proposed to investigate the characteristics of UAV-V channel. Based on the proposed model, a three-dimensional(3D) wideband channel matrix regarding channel numbers, time and delay is constructed. And some important channel characteristics parameters, such as power delay profile(PDP), root mean square(RMS) delay spread, RMS Doppler spread, channel gain and Doppler power spectral density(PSD) are investigated with different vehicle velocities. It is much simpler and clearer compared with the complex analytical derivations. The results are compared with validated analysis to confirm the theoretical analysis.

Wideband Channel Estimation for THz Massive MIMO

Terahertz(THz)communication is considered to be a promising technology for future 6G network.To overcome the severe attenuation and relieve the high power consumption,massive multipleinput multiple-output(MIMO)with hybrid precoding has been widely considered for THz communication.However,accurate wideband channel estimation,which is essential for hybrid precoding,is challenging in THz massive MIMO systems.The existing wideband channel estimation schemes based on the ideal assumption of common sparse channel support will suffer from a severe performance loss due to the beam split effect.In this paper,we propose a beam split pattern detection based channel estimation scheme to realize reliable wideband channel estimation in THz massive MIMO systems.Specifically,a comprehensive analysis on the angle-domain sparse structure of the wideband channel is provided by considering the beam split effect.Based on the analysis,we define a series of index sets called as beam split patterns,which are proved to have a one-to-one match to different physical channel directions.Inspired by this one-to-one match,we propose to estimate the physical channel direction by exploiting beam split patterns at first.Then,the sparse channel supports at different subcarriers can be obtained by utilizing a support detection window.This support detection window is generated by expanding the beam split pattern which is determined by the obtained physical channel direction.The above estimation procedure will be repeated path by path until all path components are estimated.Finally,the wideband channel can be recovered by calculating the elements on the total sparse channel support at all subcarriers.The proposed scheme exploits the wideband channel property implied by the beam split effect,i.e.,beam split pattern,which can significantly improve the channel estimation accuracy.Simulation results show that the proposed scheme is able to achieve higher accuracy than existing schemes.

Modeling and realization of mobile-to-mobile wideband MIMO channels based on the geometrical multi-ring and multi-ellipse stochastic scattering model

A geometry-based stochastic scattering model （GBSSM） based on geometrical multiple rings and ellipses is proposed for wideband multiple-input multiple-output （MIMO） mobile-to-mobile （M2M） fading channels. The proposed GBSSM is deployed with cross-polarized antennas and can be applied for the line-of-sight （LOS） and non- LOS （NLOS） scenarios by considering the single-bounced （SB） and double-bounced （DB） components. The channel realization is much more straightforward and concise to study the channel characteristics compared with the too complicated analytical solutions available so far. Based on the proposed GBSSM and realized channel, the channel characteristics and parameters at 2 GHz and 5 GHz with 100 MHz bandwidth are further investigated. The results can be used in the link and system level simulations in M2M radio systems.

Performance analysis of different coding schemes for wideband vehicle-to-vehicle MIMO systems

The signal is subjected to lots of interferences in vehicle-to-vehicle(V2V)channel propagation,resulting in receiving error codes.Two-dimensional(2D)and three-dimensional(3D)geometrical channel models are used to depict the wideband V2V multiple-input multiple-output(MIMO)channels.Using the channel model,Turbo code and low-density parity-check(LDPC)code are investigated for wideband V2V MIMO system,and the encoding and the decoding schemes are investigated.The bit error rate(BER),channel capacity and outage probability of wideband V2V MIMO system using Turbo code and LDPC code are analyzed at different typical speeds.The results show that the performance of wideband V2V MIMO system using Turbo code outperform that using LDPC code.The performance is affected by transmitting and receiving speeds with the same coding scheme.And the channel capacity of the 3D channel is larger than that of 2D channel.

A cluster-based analysis of propagation characteristics in MIMO relay channels based on wideband measurement

In this paper, the characteristics of clusters induced by a variety of propagation mechanisms in the link from the relay station （RS） to the mobile station （MS） are presented. Based on the results of high resolution channel parameter estimation, an automatic framework integrated with the manual intervention is utilized to perform the cluster identification and tracking. The power proportion and angular spread of clusters are investigated in both the line-of-sight （LOS） and non-line-of-sight （NLOS） scenarios. The measurement results indicate that the channel characteristics of clusters are different from the link from the base station to the MS due to the lower height of the RS antennas.

Dynamic denoising studies in wideband radio channel measurement and modeling

The fixed level and dynamic denoising method was studied based on indoor-to-outdoor measured channel impulse responses ORs） at 5.25 GHz with radio frequency （RF） 100 MHz bandwidth. It is found that the dynamic ranges, peak powers and noise floors of the IRs are with close correlations. The comparisons with different denoising methods are given by deriving the power delay profiles （PDPs）, root mean square （RMS） delay spread （RMS DS）, number of paths （NOPs） and Ricean K-factors. It is concluded that the traditional fixed level noise cut is under estimate of DS and NOPs. The Ricean K-factors are of little sensitive to noise cut irrespective of what kind of methods applied. The PDPs are not very sensitive to the fixed level noise cut, however, obvious changes can be found by dynamic noise cut. The dynamic noise cut is preferred when clear noise floors is observed and decided from the measured IRs, it＇s of importance in data post processing for wideband radio channel measurements as well as the relevant modeling work.