Wideband Indoor Radio Channel Research Articles

Empirical Characterization of the Indoor Radio Channel for Array Antenna Systems in the 3 to 4 GHz Frequency Band

Concerning the design and planning of new radio interfaces for the fifth-generation (5G) systems, this paper presents a useful contribution to the characterization of the wideband indoor radio channel in the 3-4-GHz frequency band. A measurement campaign has been carried out in two different indoor scenarios to analyze some of the most important wideband parameters of the propagation channel, including a thorough analysis of its behavior to meet the new radio technology challenges. The channel measurement setup consists of a virtual vertical uniform array at the receiver side of the link that remains at a fixed position, whereas the transmitter side, which is equipped with a single antenna, is placed at different positions in the environment under analysis. The measurement setup emulates the up-link of a multi-user multiple-input multiple-output (MIMO) system and allows obtaining the broadband parameters of the multiple channels that are established between the transmitter and each one of the antennas of the receiver array. The results and conclusions about the path loss, temporal dispersion, and coherence bandwidth are included, along with an analysis of the spatial correlation between wideband channels when one of the antennas is an array.

Inter-Floor Wide Band Radio Channel Measurements and Simulation Applying Saleh-Valenzuela Model

This paper explores the accuracy of Saleh-Valenzuela (SV) statistical simulation model in time of arrival domain (ToA) applied on inter-floor wide band indoor radio channels. In order to extract the model parameters, an extensive measurement campaign was performed inside a modern building by applying vector network analyzer method at frequency of 1.8 GHz. The measurement results are presented in form of path loss exponent and delay spread statistics for each number-of-floors (NOF) distance between the antennas (up to 4). Path loss exponent was found to be around 3 for antennas on a same floor and around 5.5 for any other case when antennas were on separated floors. CDFs of rms delay spread may be divided into two groups: the first group is made of single-floor (SF) case and distanced-floors (DF) cases (three or more floors separated antennas) which showed similarities performing median value at 20 ns. For neighboring-floors (NF) cases (one and two floors separation) this value was increased to 35 ns. SV simulation, run with the extracted parameters, assessed delay spread statistics sufficiently good for the first group of CDFs. In order to assess the second group results, it was necessary to introduce simple corrections in SV model application.

ESTIMATION OF ULTRA WIDE BAND CHANNEL DEGREES OF FREEDOM

Multipath propagation effects encountered in mobile wireless channels provide additional degrees of freedom [Ganesan et al., 2000] that can be exploited via appropriate signaling and reception. In this work, based on a set of measurements conducted at Eurecom, we consider a novel approach of analyzing an Ultra Wide Band (UWB) indoor radio propagation channel by performing an eigen-decomposition and observing the scaling of the number of significant eigenvalues with the channel bandwidth by using the Akaike information criterion (AIC) and Minimum Description Length (MDL). These criterion are applied to estimate the number of degrees of freedom (DoF) of an UWB in an indoor environment. We evaluate our approach under both scenarios, line-of-sight (LOS) and non-line-of-sight (NLOS). Based on AIC and the MDL criterion, we find that this number is large; this has important consequences on the receiver design. We show also, that in opposition to the accepted idea in the literature, the number of Degrees of Freedom (DoF) does not increase linearly with the channel bandwidth. Hence, the results of the estimation of UWB channel entropy confirm that the number of DoF increases sub-linearly with the channel bandwidth.

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.

Furniture effects on the wideband indoor radio channel at microwave frequencies

Typically, ray-tracing indoor simulators take into account the structural elements of the environment, but not other objects, such as furniture. Radio-channel characteristics in empty and furnished environments have been measured along linear paths by using a wideband swept-technique-based sounder in a band around 5.8 GHz. Wideband parameters, such as delay spread and coherence bandwidth, exhibit important variations when the room is furnished as opposed to the situation when it is empty. Such effects are important, so radio network designers should modify their predictions to guarantee that the performance of wideband digital communication systems will be correct. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 336–340, 2001.

Furniture effects on the wideband indoor radio channel at microwave frequencies

AbstractTypically, ray‐tracing indoor simulators take into account the structural elements of the environment, but not other objects, such as furniture. Radio‐channel characteristics in empty and furnished environments have been measured along linear paths by using a wideband swept‐technique‐based sounder in a band around 5.8 GHz. Wideband parameters, such as delay spread and coherence bandwidth, exhibit important variations when the room is furnished as opposed to the situation when it is empty. Such effects are important, so radio network designers should modify their predictions to guarantee that the performance of wideband digital communication systems will be correct. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 336–340, 2001.

Measuring, modeling, and characterizing of indoor radio channel at 5.8 GHz

Wide-band indoor radio channel characterization for broadband radio access networks and unlicensed national information infrastructure has been performed at 5.8 GHz, and results are given in this paper. Delay spreads of 8.8 and 17.2 ns and coherence bandwidths of 9.6 and 4 MHz have been found for line-of-sight (LoS) and obstructed line-of-sight (OLoS) situations, respectively. Results have been compared with predictions made using a ray-tracing tool. To get accurate predictions, a good description of the electromagnetic properties of the obstacles present in the environment is needed. Several experiments were made in order to characterize the electromagnetic parameters of six typical building materials. Transmission and reflection coefficients were measured using the free-space technique. A multiple successive internal reflection model was used to estimate the permittivity and conductivity by comparing the measured and predicted values of the coefficients. Several samples of each material were measured, and the results vary from sample to sample. This variation has been characterized by the calculation of confidence bands for the parameters. The influence of both the dielectric parameters and the order of reflections considered in the ray-tracing tool has been analyzed. The effect is reduced on narrow-band predictions but is more important on wide-band parameters as the delay spread. It is shown that the measured delay spread cumulative distribution function falls within the band predicted using the measured maximum and minimum values of permittivity.

Empirical characterization of wideband indoor radio channel at 5.3 GHz

Characteristics of wideband indoor radio channel at 5.3 GHz were defined based on an extensive measurement campaign using a wideband channel sounder with 19 ns delay resolution. Pathloss exponents were 1.3-1.5 in LOS and 2.9-4.8 in non-line of sight (NLOS). Large difference in NLOS exponents was due to different dominating propagation mechanisms in different types of building structures. The delay dispersion was characterized by cumulative distribution functions (CDF) of the RMS delay spreads, the values for CDF=0.9 varied from 20 to 180 ns in different setups in an office building and large hall environments. The correlation functions of the radio channel in spatial and frequency domains were extracted. Small scale models for five typical indoor scenarios were developed using tapped delay lines.

Effect of frequency carrier onindoor propagation channel

Experimental results obtained for narrowband and wideband indoor radio channels at 37.2 GHz and 893 MHz, respectively, are presented. Under the same line-of-sight (LOS) conditions, the multipath channel characteristics for both frequency bands are compared in terms of path loss gradient and cumulative distribution functions (CDF) of the CW measurements, and root-mean-square (RMS) delay spread of the impulse response measurements.

Analysis of antenna impact on wide-band indoor radio channel and measurement results at 1 GHz, 5.5 GHz, 10 GHz and 18 GHz

The object of this paper is to investigate the influence of antenna pattern on indoor radio channel characteristics. Different from previous works where this analysis was carried out at a fixed frequency using different antennas, in the present paper (where measurements were taken in a wide frequency range) the variation of the radiation pattern was caused by two factors: the change of the radiation pattern when the same antenna was used at different frequencies and the use of different type of antennas. To carry out this analysis, frequency domain measurements of the indoor radio channel at 1 GHz, 5.5 GHz, 10 GHz and 18 GHz were collected. Measurements were taken using a network analyzer. Several realizations of the channel transfer function were obtained varying, for each measurement, the position of the transmitter and keeping the receiver fixed. Estimate of the channel impulse response was obtained from the Inverse Fourier Transform (IFT) of the frequency response. The measurements were performed in an office environment with mostly metallic walls and inner separations. The obtained data were elaborated to obtain the power versus distance relationship, the Cumulative Distribution Functions (CDFs) of rms Delay Spread (DS) and of the 3 dB frequency correlation bandwidth. Finally, the 3 dB width of the frequency correlation function has been empirically related to the inverse of the rms DS of the impulse response.

Experimental characterization of EHF multipath indoor radio channels

This paper reports on experimental results and their interpretations for an indoor extremely high frequency (EHF) multipath channel. It is intended to help in establishing design guidelines for indoor wireless communications systems using millimeter waves. It deals with measurements obtained for the narrow and wideband indoor radio channels at 37.2 GHz within a typical concrete building at Laval University. Two kinds of transmission antennas, omnidirectional and directional, are used to investigate the propagation characteristics for the indoor channel. Under line-of-sight (LOS) conditions, the distance-power law exponent is found to be lower than the free space condition with walls playing a major role on the sustaining of high level signals. Large- and smallscale variations extracted from the original data are shown to follow log-normal and Rice distributions, respectively. The observed wideband impulse response has delay spread extending over a range up to 40 ns and a maximum root mean square (rms) value of about 16 ns. Both amplitude and phase behaviors of the signals are available for a better understanding of the various effects.

Statistics of short time and spatial variations measured in wideband indoor radio channels

In an indoor environment, channel variations which occur most frequently are due to the movement of personnel near the transmitting or receiving antennas and/or local movements of the terminals around a given location. Such spatial and short time variations in the indoor radio channel are studied and determined by per- forming wideband propagation experiments in line of sight and nonline of sight environments at 910MHz. The database is divided into two classes: spatial and short time variations. Spatial variations deal with the changes in the radio channel, observed over a short time and space, at different locations in an environment. The short time variations address changes induced over time, by human traffic close to the fixed transmitter/receiver or by manually shaking the antenna on its base. The statistics of RMS delay spread and the received power in the multipath profiles are computed and compared for these experimental variations.