Xiao Hong Mao

Propagation Modes and Temporal Variations Along a Lift Shaft in UHF Band

The guiding of electromagnetic waves along the lift shaft is studied and presented in this paper. Wideband channel sounding in UHF band along a lift shaft located in a complex environment has been conducted. Based on the measured delay in time of arrival, large structures that cause multipath clusters can be identified. The different propagation mechanisms associated with the lift shaft is then studied in detail. Analysis of the measurement results verifies the presence of electromagnetic waves being guided along the lift shaft. This guiding effect of the lift shaft is significant and is an important propagation mechanism. Temporal variation of the guided waves caused by different components of the lift shaft such as the lift door and the lift car has also been studied. Conclusions drawn from measurement results are validated using 3-D ray tracing simulation results. This research is useful for military applications such as urban warfare.

Statistical Modeling of Signal Variation for Propagation Along a Lift Shaft

Temporal variation on the tapped amplitude of propagating waves along a lift shaft in a complex campus environment is presented and modeled statistically in this letter. By using the Akaikes Information Criterion (AIC)-based method, distributions of amplitude of signals from different propagation mechanisms are studied separately. If the channel is considered as a whole, the Weibull function is identified as the best model for describing the temporal variation. The Kolmogorov-Smirnov (KS) test is applied to verify the selection of the Weibull model. Through the analysis of the Weibull b-parameter, the severe temporal variations caused by the opening and closing of the lift door and the movement of the lift car within the lift shaft can clearly be identified. Signals reflected from buildings and walls in the intermediate and far regions do not suffer from much temporal variations. The Weibull function is ideal for the statistical modeling of channel propagation along the lift shaft. Using the Weibull b -parameter, the dynamic channel along the lift shaft and the static channel from the intermediate and far regions can easily be classified.

UHF Propagation Along a Cargo Hold on Board a Merchant Ship

The characterization of a Line of Sight (LOS) and a Non-Line of Sight (NLOS) link is performed over the military Ultra High Frequency (UHF) band (225 to 450 MHz). This is done using experimental results collected inside the cargo hold of a merchant ship. By analyzing the guiding effect associated with the cargo hold and its sub-structures, the channel characteristics of the environment can be determined. This important propagation mechanism is analyzed using the 3-D ray tracing simulator. Path loss for both topologies is studied and linear path loss models are proposed. Small-scale channel characteristics, such as the number of multipath components, decay factor of the multipath components and Root-Mean-Square (RMS) delay spread are studied and compared for the LOS and NLOS scenarios. Due to the guiding effect and multiple reflections along the cargo hold, both the LOS and NLOS scenarios are found to exhibit similar channel characteristics. A linear decay function is proposed to model the average Power Delay Profiles (PDPs). It is concluded that the linear model provides a good representation for the shape of the impulse responses for a cluttered environment with reflective substructures. This study is useful for the implementation of wireless sensor networks for status monitoring in maritime applications.

Study of propagation along a lift shaft in UHF band by channel measurements and 3-D simulation

This paper presents wideband channel measurement results for radio propagation along a lift shaft in UHF military band. Propagation mechanisms associated with the lift shaft are studied. Moreover, simulation has been conducted and comparison between measurement result and simulation result is made to further discuss the propagation mechanism.

Study of path loss for ground based communication in military UHF band

Path loss along the Line-of-Sight and the Non Line-of-Sight routes in an urban environment are examined for the application of urban warfare in the military UHF band. Based on the experimental results, frequency dependency of the path loss, the path loss exponent and the corner loss are studied.

Wideband channel modeling within a shopping mall in UHF band

Wideband channel characteristics associated with UHF wave propagation within a shopping mall in urban areas are presented in this paper. Impulse responses, decay rate of multipath components as well as the root-mean-square (RMS) delay spread obtained from wideband sounding are studied for both the same level propagation and the inter-level propagation. Due to the enclosed structure of the shopping mall, multipath components are mainly resulted from multiple reflections within the building and therefore they decay linearly for both test scenarios. Moreover, the delay spread value obtained from the measurements is within 100 ns, therefore, the usable bandwidth is sufficient for video communication.

Study of guiding effect along the cargo hull of a ship by measurements and simulations

The guiding of electromagnetic waves along the cargo hull is studied and presented in this paper. Wideband channel sounding in UHF band between the bridge room and the cargo hull onboard a vessel has been conducted. Based on the periodicity of the arrival time between the multipath signals, possible analogous waveguide effect along the cargo hull is deduced. The relationship between the periodicity, the center frequency and the receiver position is then analyzed in detail. The period of signal arrival is independent of both the center frequency and the receiver position. The mean period of the signal arrival is found to correspond to the width of the cargo hull. The conclusions drawn from measurement results are validated using 3-D ray tracing simulation results. The research is useful for long distance communication aboard a metallic ship vessel for military applications.

Study of outdoor-to-indoor channel in urban area

Path loss for the outdoor-to-indoor channel in a commercial and business district is examined for the application of urban warfare in the military UHF band. The path loss exponent and link availability for different transmitting routes are studied and compared.

Propagation over the outdoor-to-indoor channel in military UHF band

Path loss for the outdoor-to-indoor channel in an urban environment is examined for the application of urban telecommunications in the UHF band. The path loss exponent and link availability for different receiver locations from within an urban office building to the outdoor urban environment are compared. This is useful for urban communication applications.

Frequency dependency of propagation along a lift shaft on board a merchant ship

Frequency dependency of wave propagation along a lift shaft on board a merchant ship is presented based on wideband channel measurement results. The maximum variation in the amplitude of the propagating waves and on the Root Mean Square (RMS) delay spread are found to be higher at 5200 MHz than 2414 MHz. The variation in average channel gain is found to be frequency independent. Although the maximum usable bandwidth is slightly lower for 2412 MHz; the higher Wi-Fi frequency of 5200 MHz has a higher propagation loss and is more sensitive to the temporal variation. Therefore, 2412 MHz is recommended for the WLAN application onboard ships with a maximum usable data rate of 1.7 Mbps for a BPSK system.