Nektarios Moraitis

Indoor channel measurements and characterization at 60 GHz for wireless local area network applications

This work presents propagation measurement results at 60 GHz in order to determine the characteristics of indoor radio channels between fixed terminals. Path loss measurements are reported for line-of-sight (LoS) and non-line-of-sight (NLoS) cases, fading statistics in a physically stationary environment are extracted and a detailed investigation of the people movement effect on the temporal fading envelope is performed. Models that presented to predict path loss provide excellent fitting with errors of 1.13 and 3.84 dB for LoS and NLoS topographies, respectively. The dynamic range of fading in a quiescent environment is 8.8 dB and increased to 35 dB when a person moves between the fixed terminals with the channel becoming extremely nonstationary. Temporal variations induced by the moving people depend on the speed, the number of individuals the body sizes and the environment. Slow fading is observed as well as a quasi-wide-sense stationary (QWSS) behavior of the fading, but up to 50 ms of time.

Measurements and characterization of wideband indoor radio channel at 60 GHz

This paper presents the measurements, the statistical results and channel models extracted by impulse response measurements of an indoor 60 GHz radio channel. The measurements were based on the pulse sounding technique. Multipath parameters that characterize the channel have been extracted and analyzed statistically concerning corridors and offices locations. The mean excess delay is in the range of 3.84 to 8.18 ns for hallways and 3.52 to 14.69 ns for offices. Additionally, rms delay spread varies from 12.34 to 15.04 ns in corridors and from 12.56 to 21.09 ns inside the laboratory. The coherence bandwidth varies between 13.88 and 30.49 MHz in corridors with a mean value of 22.48 MHz. Inside offices the mean coherence bandwidth is 22.80 MHz for LoS locations and drops to 7.05 MHz for NLoS. Small-scale models for all the measured locations were developed using tapped delay lines. The maximum Doppler frequency of the modeled channel remains around 1 Hz, whereas the coherence time is calculated 1.04 s, which indicates that the channel remains, almost stationary, exhibiting very slow fading. Finally, from the models it is derived that the channel preserves WSS and US characteristics giving rise to a WSSUS representation.

Propagation Measurements inside a B737 Aircraft for In-Cabin Wireless Networks

This paper presents a measurement campaign conducted inside a Boeing 737-400 aircraft for the development of in-cabin wireless networks. The measurements were conducted in three different frequency bands in order to provide various services. It was found that the path loss factor along the aircraft corridor varies between 2.1 and 2.3 depending on frequency. The average K-factor in the aircraft aisle was found 12.3 dB, and the dynamic range of fading between 6.2 and 7.2 dB confirming the expectation of a physically stationary channel. In the seats of the aircraft the fading statistics are increased, in comparison with the aisle, with the dynamic range to be 14.9 dB in average. The average K-factor is reduced to 7.6 dB due to the obstruction of the direct path by the passenger seat. In all cases, the fading statistics correspond very well with Rician CDF.

Propagation measurements and comparison with EM techniques for in-cabin wireless networks

This paper presents results of a narrowband measurement campaign conducted inside a Boeing 737–400 aircraft, the objective being the development of a propagation prediction model which can be used in the deployment of in-cabin wireless networks. The measurements were conducted at three different frequency bands: 1.8, 2.1, and 2.45 GHz, representative of several wireless services. Both a simple, empirical, inverse distance power law and a deterministic, site-specific model were investigated. Parameters for the empirical model were extracted from the measurements at different locations inside the cabin: aisle and seats. Additionally, a statistical characterization of the multipath scenario created by the transmitted signal and the various cabin elements is presented. The deterministic model, based on Physical Optics (PO) techniques, provides a reasonable match with the empirical results. Finally, measurements and modeling results are provided for the penetration loss into the cabin (or out of the cabin), representative of interference scenarios.

Capacity Study of a Multiple Element Antenna Configuration in an Indoor Wireless Channel at 60 GHz

This paper studies the capacity of an indoor wireless system operating at 60 GHz using a physical channel model that incorporates multiple elements at both antenna terminals. The proposed channel model utilizes the geometric characteristics of the environment, the angle of arrival and angle of departure of each one of the propagation paths, the antenna elements and their spacing. The results showed that the system capacity increases significantly if SIMO, MISO or MIMO configuration is utilized instead of the basic SISO channel. The capacity decreases, as the distance between the terminals increase. In the 90% of the cases the capacity remains above 4.3 b/s/Hz, even when the receiver is 15 m away from the base station. Finally, very high data rates, can be achieved maintaining low SNR.

Radio Channel Measurements and Characterization inside Aircrafts for In-Cabin Wireless Networks

This paper presents a measurement campaign conducted inside a large Airbus A340-300 aircraft for the development of in-cabin wireless networks. The measurements were conducted in three different frequency bands in order to provide various services. It was found that the path loss factor along the aircraft corridors varies between 2.0 and 2.7 depending on frequency. The average K-factor in the aircraft aisles was found between 9.5 and 10.1 dB, for line-of-sight (LoS) conditions, and between 3.7 and 5.0 dB for non-line-of-sight (NLoS) cases. The average dynamic range of fading varies between 12 and 14 dB for LoS, and between 25 and 28 dB for NLoS situations respectively. The maximum Doppler spread was calculated between 15 and 17 Hz, whereas the coherence time was found between 25 and 29 ms for a reference level of -3 dB.

Indoor channel modeling at 60 GHz for wireless LAN applications

This paper reports narrowband and wideband results derived by propagation modeling at 60 GHz for indoor WLAN applications. A multi-ray model is proposed and verified through a simulation process. The propagation in the site-specific environment can be described using 4-5 rays without reducing the accuracy of the results. RMS delay spread varies with distance from 0.57 ns up to 2.32 ns Coherence bandwidth for 0.9 correlation was found at 65 MHz, 116 MHz and 87 MHz for isotropic, omni-omni and horn-horn antenna configurations respectively.

Indoor Channel Capacity Evaluation Utilizing ULA and URA Antennas in the Millimeter Wave Band

This paper studies the capacity of an indoor wireless system operating at the millimeter wave band of 60 GHz using a physical channel model that incorporates smart antennas comprised by multiple elements at both antenna terminals. Two different antenna configurations were realized comprising of uniform rectangular arrays (URAs) and uniform linear arrays (ULAs). The results showed that the system capacity increases significantly if MIMO configuration is utilized instead of the basic SISO channel. The average capacity was found 5.7 b/s/Hz, for the 90% of the cases in URA scenarios, and 3.9 b/s/Hz in ULA cases. Finally, very high data rates, even higher than 1 Gb/s, can be achieved with 64times64 MIMO antenna element arrangement maintaining low SNR.

Delay spread measurements and characterization in a special propagation environment for PCS microcells

This paper reports the measurement and analysis of a wideband radio channel at 1900 MHz within a special propagation environment such as the Olympic Stadium of Athens. RMS delay spread values are evaluated as well as the coherence bandwidth of the channel is derived by the frequency correlation function. The mean delay spread is found to be 0.314 /spl mu/s and 0.731 /spl mu/s for LOS and NLOS conditions respectively. The mean coherence bandwidth that characterizes the entire area reaches 3.463 MHz providing wide transmission data rates. The correlation bandwidth is found to be inversely proportional to the RMS delay spread and modeled in a minimum mean square error sense.

Millimeter Wave Propagation Measurements and Characterization in an Indoor Environment for Wireless 4G Systems

This paper presents the measurements and the statistical results extracted by power profile measurements of an indoor 60 GHz radio channel, to assist in the development of wireless broadband systems as a part of 4G systems. The mean excess delay is in the range of 3.84 to 8.18 ns for hallways and 3.52 to 14.69 ns for offices. The rms delay spread varies from 12.34 to 15.04 ns in corridors and from 12.56 to 21.09 ns inside the offices. The coherence bandwidth varies between 13.88 and 30.49 MHz in corridors with a mean value of 22.8 MHz. Inside offices the mean coherence bandwidth is 22.80 MHz for LoS locations while drops to 7.05 MHz for NLoS. Timing jitter and standard deviation of the time delay values, remain low at all locations, and the channel does not vary significantly over 20lambda. Overall, the channel exhibits frequency selective characteristics, being extremely enhanced especially in NLoS locations