Nobutaka Omaki

Frequency-Agile Pathloss Models for Urban Street Canyons

Frequency-agile pathloss models for urban street canyons are discussed in this paper. The models are floating intercept (FI), fixed reference (FR), and ITU-R M.2135 urban microcellular (UMi) line-of-sight (LOS) and Manhattan-grid non-LOS (NLOS) models. These models are parameterized based on channel sounding campaigns in three cities covering radio frequencies ranging from 0.8 to 60 GHz. Fitting the models with measured pathloss reveals that the models are usable to cover the considered frequency range. The FI and FR models are equally simple and robust, with a slight advantage of the FI model in accuracy because of the larger number of model parameters. The original M.2135 LOS model is based on a two-ray model that includes a break point (BP). The model is extended for a better fit with measurements by including new model parameters such as a pathloss offset and a BP scaling factor that represent local scattering conditions of surrounding environments. The new model parameters are found frequency dependent in many cases. The original M.2135 model is furthermore simplified in NLOS scenarios while maintaining the model accuracy. The model parameters are derived using maximum likelihood estimation, which also showed that the modified M.2135 model offers up to 50% better accuracy compared to the FI and FR models in terms of the employed log-likelihood function (LLF). The improvement in accuracy is particularly remarkable in NLOS scenarios. A full set of parameters is provided for the models, allowing a choice for any given requirements on accuracy and complexity. Finally, applicability of the proposed models to other street canyons is discussed using independent pathloss measurements.

Path loss prediction model for 800 MHz to 37 GHz in NLOS microcell environment

Fifth generation (5G) mobile communication systems are being actively investigated to increase the system capacity. For 5G, utilizing frequency bands above 6 GHz is being investigated because it is considered that ensuring a wide frequency band above 6 GHz is relatively easier than that under 6 GHz, which is used for IMT-Advanced systems. In this report, a site general type path loss prediction model for 5G system radio link design is investigated for the above mentioned frequency band in a non-line-of-sight (NLOS) microcell environment. More specifically, based on measurement data, extending the applicable frequency range of the path loss prediction model for a hexagonal layout in a NLOS microcell environment for under 6 GHz, which is defined in Report ITU-R M.2135, is investigated. The root mean square of the prediction error (RMSE) of the original M.2135 prediction model increases with an increase in frequency; however, the model modifies the frequency term of M.2135 which improves the RMSE at higher frequencies.

Comparison of indoor penetration loss between measurement result and hybrid method by ray-tracing and physical optics

This paper investigates an indoor penetration loss between measured result and the result by a hybrid method of ray-tracing (RT) and physical optics (PO) (PT-PO method), when considering heterogeneous networks. In heterogeneous networks, interference from/to macrocell to/from small cell in indoor arrives with each other. Therefore, exact interference power estimation is essential in heterogeneous networks. From the comparison of indoor penetration loss among measured result, 3GPP model and result by RT-PO method, it is shown that the path loss between the measured result and RT-PO method agree well with each other when considering the severe interference environment.

Investigation of Ray Tracing accuracy in street cell environment in high-SHF band

Recently, mobile networks employing high-speed high-capacity communications have been investigated extensively to satisfy the demand for the faster and larger data communication. As one of the approaches, High-SHF (6-30 GHz) and EHF (mainly 30-60 GHz) bands are the candidates to utilize the relatively wide frequency band widths. As one approach, High-SHF (6-30 GHz) and EHF (mainly 30-60 GHz) bands are candidates to utilize the relatively wide frequency bandwidths. Accordingly, the characteristics of radio propagation loss in the frequency bands must be characterized. We investigate the characteristics of radio propagation loss in a street cell environment in the High-SHF bands using Ray Tracing (RT) based on measurement results. We observe that RT calculation tends to exhibit estimation error as the frequency increases.