Wideband Millimeter-Wave Channel Characterization in an Open Office at 26 GHz

Based on the newest frequency allocation for the fifth generation (5G) radio systems at 26 GHz millimeter wave band by the World Radio Communications Conference, this paper investigates the wideband channel properties by measurements carried out in the LOS and NLOS environments at 26 GHz with 1 GHz bandwidth in an open office at KeySight Beijing, China, which is a representative of an indoor hotspot scenario. In the time domain measurements, an omni-directional biconical horn is used at the transmitter, while at the receiver a 24.3 dBi horn is applied and rotated with 5° angular step in the whole azimuth plane, and from ?20° to 30° in the elevation plane with 10° angular step. In the work, two kinds of path-loss models are developed, namely directional and omni-directional models by using close-in and float intercept methods. The directional path-loss model is useful for adopting beamforming techniques. The large scale channel parameters such as the shadow fading, root mean square (RMS) delay spread, RMS angular spread in the azimuth and elevation planes, Ricean K-factor, number of clusters and their correlations are investigated for the fifth generation (5G) link and system level simulations. A new method for extracting number of clusters is proposed to find the peak power within a sliding window. The power angular profiles are employed at the measurement locations for propagation mechanisms studies. We believe that the newest results in this work are useful in the simulations and planning for future 5G radio systems at 26 GHz.     

Ultra-Wide Patch Antenna Array Design at 60 GHz Band for Remote Vital Sign Monitoring with Doppler Radar Principle

In this paper, ultra-wide patch antenna arrays have been presented at 60 GHz band (57.24–65.88 GHz) with improved gain and beam-width capabilities for remote detection of respiration and heart beat rate of a person with Doppler radar principle. The antennas measured and simulation results showed close agreement. The breathing rate (BR) and heart rate (HR) of a 31-year-old man have been accurately detected from various distances ranging from 5 to 200 cm with both single-antenna and dual-antenna operations. In the case of single-antenna operation, the signal is transmitted and received with the same antenna, whereas in dual-antenna operation, two identical antennas are employed, one for signal transmission and the other for reception. It has been found that in case of the single-antenna operation, the accuracy of the remote vital sign monitoring (RVSM) is good for short distance; however, in the case of the dual-antenna operations, the RVSM can be accurately carried out at relatively much longer distance. On the other hand, it has also been seen that the visual results are more obvious with higher gain antennas when the radar beam is confined just on the subject’s body area.     

Review of Wireless Personal Communications Radio Propagation Models in High Altitude Mountainous Areas at 2.6 GHz

This paper presents five commonly used radio propagation models (RPMs) which are suitable for the prediction of path loss in macrocell environments of LTE wireless communication systems. These RPMs’ application in high altitude mountainous areas networks (HAMANETs) environment requires further validation and studies. Through using the measured path loss in the HAMANETs at 2.6 GHz to calculate the predicted value of the five RPMs and the measured value’s mean error (ME), root mean square error, and error standard deviation (ESTD), we verified the predicted value of the SPM model that is closer to the actual measurement. On this basis, the empirical propagation model in HAMANETs environment is corrected. When correcting, a method to calculate base station’s effective antenna height and propagation distance is provided by using the altitude above sea level data. This method can reduce the error that the mountainous areas are simplified to the flat-terrain in the existed propagation models. A linear least square method is used to calculate the optimal propagation model. Finally, the ME is the smallest, and the ESTD is less than 8 dB, which indicate that the corrected propagation model is more suitable for the actual environmental path loss’s prediction. The results show that the path loss factor of the test area is about 65 dB, including the influence of the high altitude, mountains, vegetation, and air humidity in HAMANETs environment. The study results can provide useful advice to the evaluation and verification of personal wireless communications in the HAMANETs. Furthermore, using the correction method proposed in this paper can correct propagation models suitable for the different propagation environments to improve the accuracy and efficiency of wireless network optimization.     

Compact Efficient Feed-Horn at 30–38 GHz for a Multi-beam Radio Telescope

The requirements for a feed suitable for a radio telescope multi-beam focal plane array are considered. A smooth-walled spline-profile horn covering the 30–38 GHz frequency band to be used in a multi-beam receiving array of a radio telescope has been optimized, manufactured and tested. The achieved cross-section aperture size of the horn allows us to provide a neighboring beam spacing equal or less than 2HPBW for the RATAN-600 radio telescope. The measured sidelobe levels of the radiation pattern is less than −30dB/−24dB/−26dB in H/E/45⁰-planes, cross-polarization levels better than −20 dB, an input return loss better than −18 dB and the −3dB/−10dB-beamwidths are of the order of 40o/ 80o over the frequency band. Mutual-coupling of adjacent horns is less than −38 dB.     

Comparisons of system architectures for microwave-photonics transmissions at 60 GHz

We report here on different system architectures for a wireless link operating in the 60 GHz range, which has a high potential for use in short range and highly secure high data rate applications. The millimetre wave around 60 GHz is generated by photonic heterodyning or microwave-photonics using radio-over-fibre concept of transmission. Low error transmission using two techniques at data rates up to 4.2 Gb/s is experimentally demonstrated.     

Channel Sounding System for MM-Wave Bands and Characterization of Indoor Propagation at 28 GHz

The aim of this work is to present a vector network analyzer based channel sounding system capable of performing measurements in the range from 2 to 50 GHz. Further, this paper describes an indoor measurement campaign performed at 26–30 GHz. The sounding system is capable of receiving two channels and transmitting one. Using this feature a channel measurement has been performed using both a directional horn antenna and a virtual uniform circular array (UCA) at the same time. This allows for comparative studies of measured channels with two different antennas in a simultaneous way. The measurement has been conducted with 42 measurement positions distributed along a 10 m long path through an indoor laboratory environment. The transmitter was positioned such that measurements were conducted both in line-of-sight and non-line-of-sight scenarios. The measurements showed good agreement between the measurement data collected with the horn antenna and the data collected with the UCA. The propagation environment was found to be sparse both in delay and angular domain for the given scenario. Based on the performed measurement campaign together with validation measurements of the system stability, it is found that the system works as expected.     

Measurement of Rain Induced Attenuation over a Line of Sight Link Operating at 28.75 GHz at Amritsar (INDIA)

The need of higher bandwidth systems has led the system designer to shift into higher frequency region. But working at these high frequency regions is not that easy. The paper presents results of the measurements of rain induced attenuation of a LOS link operating at 28.75 GHz at Amritsar (31°36′ N 74° 52′ E) for a single event that occurred on the 15th Nov., 2004. The results have been compared with those of ITU-R Model. It is observed that there is a significant difference between the attenuation levels measured and those predicted by using ITU-R model.     

Indoor Radio Propagation and Interference in 2.4 GHz Wireless Sensor Networks: Measurements and Analysis

In wireless sensor networks (WSNs), the performance and lifetime are significantly affected by the indoor propagation and the interference from other technologies using the 2.4 GHz band. Next to an overview of the propagation and coexistence issues in the literature, we present a model for analysing these effects in WSNs. We also present our measurements results on the indoor propagation, the interference of the microwave oven (MWO) and their impact on the performance of the WSN. The propagation measurements reveal significant influence of the multipath: changing a node position with a few centimetres or changing the communication channel can lead up to 30 dB difference in the received power. The power leakage of MWO has been observed around $-$ 20 dBm at 1 m distances to the oven. This leads to extra retries of the 802.15.4 messages which matches our simulation results: the packet success ratio at first try decreases to 30–40 %, which increases the average active time of the sensor, closely located to the MWO. We observe that the ON–OFF pattern of the MWO could be exploited by WSNs to improve the performance.     

Design of a Low Voltage Highly Linear 2.4 GHz Up-Conversion Mixer in 0.18 μm CMOS Technology

This paper presents a low voltage highly linear up-conversion mixer for 2.4 GHz IEEE 802.11b WLAN transmitter applications based on a Chartered 0.18 μm CMOS technology. In the proposed mixer, the double balanced Gilbert cell topology was adopted and the dual resistive current-reuse and current-bleeding techniques in both the driver and switching stages with a capacitive cross-coupling technique were used. The up-conversion mixer can convert a 10 MHz intermediate frequency signal to a 2.4 GHz radio frequency signal, with a local oscillator power of 0 dBm at 2.39 GHz. A comparison with conventional CMOS mixer shows that this up-conversion mixer has advantages of low voltage, low power consumption and high performance. The post-layout simulation results demonstrate that at 2.4 GHz, the circuit provides 7.1 dB of conversion gain and the input-referred third-order intercept point of 11.3 dBm, while drawing only 5 mA for the mixer core under a supply voltage of 1.2 V. The chip area including testing pads is only 0.65 × 0.75 mm.     

60 GHz amplifier employing slow-wave transmission lines in 65-nm CMOS

A three-stage V-band amplifier implemented in 65-nm baseline CMOS technology is presented in this paper. Slow-wave coplanar waveguides are used for matching and interconnects to study the benefits of using this line type in amplifier design. Measured power gain, noise figure and 1 dB output compression point at 60 GHz are 13 dB, 6.3 dB and +4 dBm, respectively. The amplifier has 19.6 GHz of 3 dB bandwidth, thus covering entirely the unlicensed band around 60 GHz. The performance is achieved with a 1.2 V supply and 45 mA DC current consumption.     

A New Approach to Suppress the Effect of Machining Error for Waveguide Septum Circular Polarizer at 230 GHz Band in Radio Astronomy

A new stepped septum-type waveguide circular polarizer (SST-CP) was developed to operate in the 230 GHz band for radio astronomy, especially submillimeter-band VLBI observations. For previously reported SST-CP models, the 230 GHz band is too high to achieve the design characteristics in manufactured devices because of unexpected machining errors. To realize a functional SST-CP that can operate in the submillimeter band, a new method was developed, in which the division surface is shifted from the top step of the septum to the second step from the top, and we simulated the expected machining error. The SST-CP using this method can compensate for specified machining errors and suppress serious deterioration. To verify the proposed method, several test pieces were manufactured, and their characteristics were measured using a VNA. These results indicated that the insertion losses were approximately 0.75 dB, and the input return losses and the crosstalk of the left- and right-hand circular polarization were greater than 20 dB at 220–245 GHz on 300 K. Moreover, a 230 GHz SST-CP was developed by the proposed method and installed in a 1.85-m radio telescope receiver systems, and then had used for scientific observations during one observation season without any problems. These achievements demonstrate the successful development of a 230 GHz SST-CP for radio astronomical observations. Furthermore, the proposed method can be applicable for observations in higher frequency bands, such as 345 GHz.     

The Studies of Millimeter Waves at 60 GHz in Outdoor Environments for IMT Applications: A State of Art

As the growth of mobile technology network increasing exponentially due to which radio frequency becomes more valuable natural resources. Shortage of bandwidth creates an enormous opportunities for researchers and engineers for exploration of underutilize millimeter wave spectrum in order to design and develop future technologies. It is a need of an hour to do extensive studies on the impact of millimeter wave technologies as both indoor and outdoor environments. This paper describes the various studies carried out earlier in the field of radio wave propagation at 60 GHz in different outdoor environments.     

An Indoor Propagation Model Based on a Novel Multi Wall Attenuation Loss Formula at Frequencies 900 MHz and 2.4 GHz

This paper describes an indoor propagation model pertaining to a sample of six different multi-floor building structures that have a stone block type outer wall and are generally described as university, hospital and office type buildings. Those flat roofed, stone built, multi floor buildings are very common, not only in Palestine, but probably in vast areas in the Middle East region. The goal is to come up with a relatively general model that would be both reliable and representative to a wider sample of multi-floor buildings, falling under a similar building structure classification. The improved model; we name the AMATA model, lends itself to its generalization for the GSM and wireless LAN frequencies as well as the developed multiwall effective attenuation fourth power nonlinear equation that solely relies on the number of wall separations within the floor. A clear improvement in the standard deviation of the mean path loss resulted in comparison to the well known indoor ITU path loss model. Our model can be applied with a high confidence level to the wider range of buildings similar to the classification type of the building structure sample, we conducted measurements upon.     

4 × 2 × 20 Gbit/s-40 GHz Hybrid Spectrum-Sliced WDM-MDM Based Radio over FSO Transmission Link Under the Effect of Atmospheric Turbulence

Wireless Personal Communications - This article proposes a novel high data rate radio-over-free-space-optical link by combining wavelength-division multiplexed (WDM)-orthogonal frequency-division...     

Propagation Path Loss and Materials Insertion Loss in Indoor Environment at WiMAX Band of 3.3 to 3.6?GHz

The purpose of this study is to characterize the indoor channel for IEEE 802.16 (WiMAX) at 3.3?C3.6?GHz frequency. This work presents a channel model based on measurements conducted in commonly found scenarios in buildings. These scenarios include closed corridor, wide corridor and semi open corridor. Path loss equations are determined using log-distance path loss model and a Rayleigh multipath induced fading, Normal multipath induced fading or a combination of both. A numerical analysis of measurements in each scenario was conducted and the study determined equations that describe path loss for each scenario. Propagation loss is given for 300?MHz bandwidth. This work also represents the insertion loss of different materials and the obstruction loss due the existence of human beings between the transmitting antenna and the receiving one.     

Estimation of Path Length Reduction Factor by Using One Year Rain Attenuation Statistics over a Line of Sight Link Operating at 28.75 GHz in Amritsar (INDIA)

The effect of environmental factors in general and rain droplets in particular, on microwave propagation is a very well known fact now. If the rain droplets are present in an inhomogeneous way across the path length of the microwave communication system then, a new concept of path length reduction factor is introduced which accounts for the inhomogeneous nature of the rain droplets along the path length of the microwave signal. The present paper presents results of path length reduction factor using data on attenuation levels obtained on a LOS link operating at 28.75 GHz in Amritsar region and its comparison with Crane’s and ITU-R’s model.