23 research outputs found
Millimeter Wave Channel Measurements in a Railway Depot
Millimeter wave (mmWave) communication is a key enabling technology with the
potential to deliver high capacity, high peak data rate communications for
future railway services. Knowledge of the radio characteristics is of paramount
importance for the successful deployment of such systems. In this paper mmWave
channel measurements are reported for a railway environment using a wideband
channel sounder operating at 60GHz. Highly directional antennas are deployed at
both ends of the link. Data is reported for path loss, root mean square (RMS)
delay spread and K-factor. Static and mobile measurements are considered.
Analysis shows that the signal strength is strongly dependent (up to 25dB) on
the azimuth orientation of the directional transmit and receive antennas. A
path loss exponent of n=2.04 was extracted from the Line-of-Sight measurements
with optimally aligned antennas. RMS delay spreads ranged from 1ns to 22ns
depending on antenna alignment. 50% of the measured K-factors were found to be
less than 6dB. We conclude this is the result of ground reflections in the
vertical Tx-Rx plane
Location-aided mm-wave channel estimation for vehicular communication
Millimeter-wave (mm-wave) communication is a promising technology for next-generation wireless systems. One challenging application lies in the vehicular domain, where mm-wave should support ultra-fast and high-rate data exchanges among vehicles and between vehicles and infrastructure. To achieve ultra-fast initial access between nodes, we propose a location-aided beamforming strategy and analyze the resulting performance in terms of antenna gain and latency. We find that location information can significantly speed up initial access
Adaptive Multi-state Millimeter Wave Cell Selection Scheme for 5G communication
Millimeter wave bands have been introduced as one of the most promising solutions to alleviate the spectrum secrecy in the upcoming future cellular technology (5G) due the enormous amount of raw bandwidth available in these bands. However, the inherent propagation characteristics of mmWave frequencies could impose new challenges i.e. higher path loss, atmospheric absorption, and rain attenuation which in turn increase the outage probability and hence, degrading the overall system performance. Therefore, in this paper, a novel flexible scheme is proposed namely Adaptive Multi-State MmWave Cell Selection (AMSMC-S) through adopting three classes of mmWave base stations, able to operate at various mmWave carrier frequencies (73, 38 and 28 GHz). Two mmWave cellular Grid-Based cell deployment scenarios have been implemented with two inter-site-distances 200 m and 300 m, corresponding to target area of (2.1 km2) and (2.2 km2). The maximum SINR value at the user equipment (UE) is taken in to consideration to enrich the mobile user experience. Numerical results show an improvement of overall system performance, where the outage probability reduced significantly to zero while maintaining an acceptable performance of the 5G systems with approximately more than 50% of the mobile stations with more than 1Gbps data rate.
MmWave System for Future ITS:A MAC-layer Approach for V2X Beam Steering
Millimeter Waves (mmWave) systems have the potential of enabling
multi-gigabit-per-second communications in future Intelligent Transportation
Systems (ITSs). Unfortunately, because of the increased vehicular mobility,
they require frequent antenna beam realignments - thus significantly increasing
the in-band Beamforming (BF) overhead. In this paper, we propose Smart
Motion-prediction Beam Alignment (SAMBA), a MAC-layer algorithm that exploits
the information broadcast via DSRC beacons by all vehicles. Based on this
information, overhead-free BF is achieved by estimating the position of the
vehicle and predicting its motion. Moreover, adapting the beamwidth with
respect to the estimated position can further enhance the performance. Our
investigation shows that SAMBA outperforms the IEEE 802.11ad BF strategy,
increasing the data rate by more than twice for sparse vehicle density while
enhancing the network throughput proportionally to the number of vehicles.
Furthermore, SAMBA was proven to be more efficient compared to legacy BF
algorithm under highly dynamic vehicular environments and hence, a viable
solution for future ITS services.Comment: Accepted for publication in IEEE VTC Fall 2017 conference proceeding
Investigation of Prediction Accuracy, Sensitivity, and Parameter Stability of Large-Scale Propagation Path Loss Models for 5G Wireless Communications
This paper compares three candidate large-scale propagation path loss models
for use over the entire microwave and millimeter-wave (mmWave) radio spectrum:
the alpha-beta-gamma (ABG) model, the close-in (CI) free space reference
distance model, and the CI model with a frequency-weighted path loss exponent
(CIF). Each of these models have been recently studied for use in standards
bodies such as 3GPP, and for use in the design of fifth generation (5G)
wireless systems in urban macrocell, urban microcell, and indoor office and
shopping mall scenarios. Here we compare the accuracy and sensitivity of these
models using measured data from 30 propagation measurement datasets from 2 GHz
to 73 GHz over distances ranging from 4 m to 1238 m. A series of sensitivity
analyses of the three models show that the physically-based two-parameter CI
model and three-parameter CIF model offer computational simplicity, have very
similar goodness of fit (i.e., the shadow fading standard deviation), exhibit
more stable model parameter behavior across frequencies and distances, and
yield smaller prediction error in sensitivity testing across distances and
frequencies, when compared to the four-parameter ABG model. Results show the CI
model with a 1 m close-in reference distance is suitable for outdoor
environments, while the CIF model is more appropriate for indoor modeling. The
CI and CIF models are easily implemented in existing 3GPP models by making a
very subtle modification -- by replacing a floating non-physically based
constant with a frequency-dependent constant that represents free space path
loss in the first meter of propagation.Comment: Open access available at:
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=743465