Yohei Konishi

Large Scale Parameters and Double-Directional Characterization of Indoor Wideband Radio Multipath Channels at 11 GHz

This paper presents the large scale parameters of wideband multipath channels based on extensive measurement campaigns in various indoor environments. The measurements were conducted with a wideband multiple-input multiple-output (MIMO) channel sounder having a bandwidth of 400 MHz at 11 GHz which is a challenging frequency for future mobile systems. In particular, polarization characteristics of path-loss, shadowing, cross-polarization power ratio (XPR), delay spread and coherence bandwidth are characterized. The measurement results show that the path-loss exponents range between 2.0 and 3.0 for none-line-of-sight (NLoS), 0.36 and 1.5 for LoS, respectively. Vertically and horizontally polarized transmissions have almost same path-gain, but in some corridor-room NLoS environments, the path-loss for HH is significantly large. In most cases, the RMS delay spreads are less than 20 and 50 ns for NLoS and LoS, respectively, and the average coherence bandwidth is less than 30 MHz. The Rician K-factors range between 2 and 3 dB for cross-polarization, and in large Hall environments, those for co-polarization are greater than 6.0 dB with 10% probability. Finally, some dominant propagation mechanism and site-specific behaviors are illustrated using the double-directional measurement results.

Novel Scalable MIMO Channel Sounding Technique and Measurement Accuracy Evaluation With Transceiver Impairments

This paper presents a novel multiple-input-multiple-output (MIMO) channel sounding technique with a fully parallel transceiver architecture that employs a layered scheme of frequency and space-time division multiplexing. It offers inherent scalability of the number of antennas by a combination of multiple transceiver units and flexibility for both directional MIMO channel and multi-link MIMO channel measurements. This paper describes the principle of the channel sounding technique and formulates the signal processing that makes possible various scalable unit configurations. The influence of the transceiver imperfections such as I/Q imbalance (IQI) and phase noise (PN) on the measurement accuracy is discussed, and a multitone allocation scheme that is robust against IQI is also introduced. Using computer simulations, the measurement accuracy in the presence of IQI and PN is evaluated using the normalized mean square error, which provides a design guideline for the realization of hardware.

Development of 4×4 full-MIMO channel sounder operating at 11 GHz with 400 MHz bandwidth utilizing software radio architecture

This paper reports the development of MIMO channel sounder operating at 11 GHz with 400 MHz bandwidth. The sounder utilizes the software radio architecture to measure the full MIMO channels simultaneously, since the same hardware can be also used to test the real-time data transmission.

Cluster polarization behavior of a MIMO system: Measurement, modeling and statistical validation of the correlation of its channel parameters

This paper presents clusterwise polarization characteristics based on an estimated MIMO channel of a small urban macrocell at 4.5 GHz. Polarization path gain, cross-polarization ratio, and co-polarization ratio characteristics as influenced by channel parameters such as delay, azimuth and elevation angle of arrival were investigated. Hypothesis testing was used as a verification of the results. This statistical verification clarifies the independence of polarization characteristics from an azimuth angle of arrival, whereas some correlation was found between the cross-polarization ratio and the elevation angle of arrival. The results also confirmed a log-normal cross-polarization ratio.