Channel Characteristics Analysis of Angle and Clustering in Indoor Office Environment at 28 GHz

The millimeter-wave band will be one of the most key components in the next generation wireless communication system. In this paper, a radio channel measurement was conducted in an indoor office environment at 28 GHz with 500 MHz bandwidth. The channel sounder with the clock synchronization was used to measure in both line-of-sight (LoS) and none- line-of-sight (NLoS) scenarios. The channel impulse responses (CIRs) are recorded with an omnidirectional antenna at TX and a horizontal-rotating horn antenna fixed at the same height at RX as references. The space-alternating generalized expectation-maximization (SAGE) algorithm was applied to extract the channel characteristics of multipath components (MPCs) from the synthesized CIRs, and then the direct synthesized CIRs and the CIRs constructed from SAGE results were compared in terms of power delay profiles (PDPs) and power angular spread (PAS). It is found that the reconstructed results closely approximate real results. In addition, the cluster numbers and the inner-cluster root mean square (RMS) angle spreads are drawn after the clustering analysis and they cohere with the changes of the corresponding surrounding environment of the point, regardless of LoS or NLoS. The wireless channel propagation at 28 GHz is heavily dependent on the environment because the linear and reflective propagation are the main mode of transmission.