| 41. |
- Abbas, Taimoor, et al.
(author)
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Line-of-Sight Obstruction Analysis for Vehicle-to-Vehicle Network Simulations in a Two Lane Highway Scenario
- 2013
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In: International Journal of Antennas and Propagation. - : Hindawi Limited. - 1687-5869 .- 1687-5877. ; 2013
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Journal article (peer-reviewed)abstract
- In vehicular ad-hoc networks (VANETs) the impact of vehicles as obstacles has largely been neglected in the past. Recent studies have reported that the vehicles that obstruct the line-of-sight (LOS) path may introduce 10-20 dB additional loss, and as a result reduce the communication range. Most of the traffic mobility models (TMMs) today do not treat other vehicles as obstacles and thus can not model the impact of LOS obstruction in VANET simulations. In this paper the LOS obstruction caused by other vehicles is studied in a highway scenario. First a car-following model is used to characterize the motion of the vehicles driving in the same direction on a two-lane highway. Vehicles are allowed to change lanes when necessary. The position of each vehicle is updated by using the car-following rules together with the lane-changing rules for the forward motion. Based on the simulated traffic a simple TMM is proposed for VANET simulations, which is capable to identify the vehicles that are in the shadow region of other vehicles. The presented traffic mobility model together with the shadow fading path loss model can take in to account the impact of LOS obstruction on the total received power in the multiple-lane highway scenarios.
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| 42. |
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| 43. |
- Abbas, Taimoor, et al.
(author)
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Measurement-Based Analysis: The Effect of Complementary Antennas and Diversity on Vehicle-to-Vehicle Communication
- 2013
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In: IEEE Antennas and Wireless Propagation Letters. - 1548-5757. ; 12:1, s. 309-312
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Journal article (peer-reviewed)abstract
- In vehicle-to-vehicle (V2V) communication systems the antennas are prone to shadowing and the antenna gain is dissimilar even for same antenna elements if mounted at different positions on the car. This paper investigates the impact of antenna placement based on channel measurements performed with four omni-directional antennas mounted on the roof, bumper, windscreen and left-side mirror of the transmitter and receiver cars. Results suggest to use antennas with complementary characteristics, e.g., antennas on each side, mounted on the roof and bumper, to exploit diversity and decrease the effect of shadowing.
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| 44. |
- Abbas, Taimoor, et al.
(author)
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Measurements Based Channel Characterization for Vehicle-to-Vehicle Communications at Merging Lanes on Highway
- 2013
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In: 2013 IEEE 5th International Symposium on Wireless Vehicular Communications, WiVeC 2013 - Proceedings. - : IEEE. - 9781467363396
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Conference paper (peer-reviewed)abstract
- This paper presents results for vehicle-to-vehicle channel characterization based on measurements conducted for the merging lane scenarios on a highway. We present power delay profiles as well as channel gains and analyze important propagation mechanisms to see the impact of line-of-sight (LOS) and the antenna radiation pattern on the total received power. It is found that the absence of LOS and strong scattering objects, close to the point where the ramp merges with a highway, may result in poor received signal strength. The probability of dropping packets also increases where there is LOS between TX and RX but the antenna pattern is not omni-directional. A dip in the antenna pattern affects the received signal strength severely which poses a challenge for vehicle-to-vehicle communication in safety critical situations.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
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| 49. |
- Abbas, Taimoor, et al.
(author)
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System Identification in GSM/EDGE Receivers Using a Multi-Model Approach
- 2012
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In: International Journal on Control System and Instrumentation. - 2158-0006. ; 3:1, s. 41-46
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Journal article (peer-reviewed)abstract
- Model order selection is an important element in system identification. It is well known that common model order selection methods such as Akaike’s information criterion (AIC) and Bayesian’s information criterion (BIC) neglect relevant information that is available in models of order different from the one chosen. In this paper the model order selection problem for receivers similar to those found in GSM and EDGE systems is reviewed briefly and is solved with a multi-model approach based on simultaneous consideration of several models. Two methods are evaluated; a multi-model noise suppression filter and multi-model soft combining. The algorithms are implemented and evaluated by means of simulations. The performance of each method is analyzed for GSM and EDGE receivers in a link level simulator. Simulation results show a significant improvement in performance at the cost of increased computational complexity for the multi-model approach.
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| 50. |
- Abbas, Taimoor, et al.
(author)
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Validation of a Non-Line-of-Sight Path-Loss Model for V2V Communications at Street Intersections
- 2013
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In: 13th International Conference on ITS Telecommunications.
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Conference paper (peer-reviewed)abstract
- In this paper a non-line-of-sight (NLOS) path-loss and fading model developed for vehicle-to-vehicle (V2V) communication at 5:9 GHz is validated with independent and realistic measurement data. The reference NLOS model is claimed to be flexible and of low complexity, and incorporates specific geometric aspects in a closed-form expression.We validated the accuracy of the model with the help of realistic channel measurements performed in selected street intersections in the city of Lund and Malm¨o, Sweden. The model fits well, with a few exceptions, to most of the measurements taken at different intersections which have variable geometry and scattering environment. It is found that the model can be made more general if an intersection dependent parameter, that depends on the property and number of available scatterers in that particular intersection, is included in the model.
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