Millimeter Wave Wireless Channel Measurement Modeling And Parameter Estimation Aldorithm

The global bandwidth shortage currently experienced by mobile cellular carriers has motivated the exploration of the millimeter-wave(mm Wave)frequency spectrum,which is a key enabler for the 5G.The mm Wave channel propagation characterization is important for the design and deployment of the 5G network.In field measurements at millimeter-wave(mm Wave)frequencies,the spatial propagation characteristics are usually obtained by using steerable highgain horn antennas to compensate the large path loss.However,it is a challenging issue to deembed antenna patterns from the observed channel responses.This paper has the following contributions.(1)According to the millimeter wave channel sounding process,a new spatial channel convolution signal model is proposed,which helps to deembed the antenna impact and also reconstruct conveniently the synthetic channel responses.(2)A low-complexity antenna deembedding algorithm based on pseudo-inverse,including two steps of deconvolutions,is proposed.Second,a field measurement campaign on the frequency-space mm Wave channels in an office is presented to validate the method.The channels were sounded at 72.5 to 73.5 GHz using three horn antennas with different beam widths and gains.The omnidirectional angular channel responses(ACRs)were measured by rotating the receiver antenna.The observed and reconstructed ACRs are consistent,and the estimated antenna-free angular propagation profiles by using different horn antennas are also highly correlated,which validate the proposed antenna deembedding approach.Furthermore,the omnidirectional transfer functions in the mm Wave band obtained using different horn antennas are compared,and the channel coherence bandwidth is analyzed based on the autocorrelation of the transfer functions.(3)An antenna De-embedding Algorithm Based on Tikhonov Regularization is proposed.By suppressing parts of the observed response which are disguised by noise,the Tikhonove regularization facilitates the deconvolution of antenna pattern and thus enables the extraction of propagation models with low computational complexity in the WND.An optimization algorithm has been designed to select the appropriate regularization factor to minimize the impact of deconvolved noise.The accurately reconstructed principle peaks and interpolated oscillations in the synthesized channel responses are highly coincident with the observations,which verifies that the proposed approach can effectively de-embed the antenna effect.(4)We performed extensive measurements on the O2 I propagation at 3.5,4.9,and 28 GHz simultaneously by using a multi-band channel sounder.The path loss distribution over a typical residential building was obtained.It is found that the mm Wave band can provide reliable coverage in outer rooms by propagation through exterior windows,but cannot for inner parts of a building.The path loss increases by 1.5 and 6 d B/meter with the depth into a building in the LOS and NLOS cases,respectively.The sub6 G bands can provide good coverage over the whole building thanks to the much smaller penetrate loss through the walls.We have also captured the angular power arrival profiles at 28 GHz by steering a horn antenna horizontally and found that the reflections by walls make the main contribution for the full coverage in a room.