UltraWideband Channel Model for IntraVehicular Wireless Sensor Networks
Ultra-Wideband Channel Model for Intra-Vehicular Wireless Sensor Networks C. Umit Bas Electrical and Electronics Engineering , Koc University
History of In-Vehicle Networking Early days of automotive electronics Each new function implemented as a stand-alone ECU, subsystem containing a microcontroller and a set of sensors and actuators Data exchanged between point-to-point links Body Control Module ECU sensor
History of In-Vehicle Networking In the 1990 s Increase in the number of wires and connectors caused weight, cost, complexity and reliability problems Developments in the wired communication networks Body Control Module ECU sensor ECU actuator sensor
History of In-Vehicle Networking In the 1990 s Increase in the number of wires and connectors caused weight, cost, complexity and reliability problems Developments in the wired communication networks Multiplexing communication of ECUs over a shared link called bus Body Control Module ECU sensor ECU actuator sensor
History of In-Vehicle Networking Today Increases in number of sensors as electronic systems in vehicles are replacing purely mechanical and hydraulic systems causes weight, cost, complexity and reliability problems due to wiring Advances in low power wireless networks and local computing Body Control Module sensor ECU ECU sensor actuator sensor
History of In-Vehicle Networking Today Increases in number of sensors as electronic systems in vehicles are replacing purely mechanical and hydraulic systems causes weight, cost, complexity and reliability problems due to wiring Advances in low power wireless networks and local computing Intra-Vehicular Wireless Sensor Networks (IVWSN) Body Control Module sensor ECU ECU sensor actuator sensor
Motivation for Intra-Vehicular Wireless Sensor Networks Provide savings in Part cost Cost of assembly, repair and maintenance Fuel consumption Decreases cost of change/inflexibility Cabling connectivity has little design flexibility and upgrades Enable new sensor technologies to be integrated into vehicles E. g. tire pressure monitoring systems, intelligent tire Replace current sensors not functioning well enough due to cabling.
IVWSN: Distinguishing Characteristics Tight interaction with control systems Sensor data used in the real-time control of mechanical parts in different domains of the vehicles Very high reliability Same level of reliability as the wired equivalent Energy efficiency Remove wiring harnesses for both power and data Heterogeneity Wide spectrum for data generation rate of sensors in different domains Harsh environment Large number of metal reflectors, a lot of vibrations, extreme temperatures Short distance Maximum distance in the range 5 m-25 m
What is UWB? Transmission from an antenna for which the emitted signal bandwidth exceeds the lesser of 500 MHz and 20% of the center frequency.
Motivation for Ultra-Wideband Vehicle control systems require Very high reliability, Strict delay guarantee. UWB provides Resistance to multipath fading, Resistance to power loss due to lack of line of sight, Resistance to interference, Robust performance at high data rate with very low transmit power.
Wireless Channel Measurements Building a detailed model for IVWSN requires Classifying the vehicle into different parts of similar propagation characteristics Collecting multiple measurements at various locations belonging to the same class passenger compartment engine trunk beneath chassis
Literature Review
Measurement Setup Agilent 8719 ES Vector Network Analyzer 3. 1 GHz to 10. 6 GHz using 1601 points
Measurement Locations 18 transmitter locations & 1 receiver location At each location 9 antenna positions on 3 x 3 square grids with 5 cm spacing Totally 81*18 measurement points
Data Processing
Large & Small Scale Fading Statistics Large-Scale Statistics 81 measurements at each location averaged to obtain the small-scale averaged PDP (SSA-PDP) Large-scale statistics derived by using 18 SSA-PDP Small-Scale Statistics Variations of 81 Local PDP around SSA-PDP used to derive small-scale statistics
Large Scale Statistics Modeled by using small scale averaged power delay profiles (SSA-PDP) for 18 locations
Path Loss Model
General Shape of Impulse Response Modified Saleh-Valenzuela Model inter-arrival time of clusters cluster amplitude ray decay rate
Small Scale Statistics Characterized by fitting amplitude values of 81 local PDP to alternative distributions
Distribution of Amplitudes for Delay Bins
σ of Lognormal Distributions σ is independent of time
σ of Lognormal Distributions means of σ have no trivial relation with distance
σ of Lognormal Distributions Small scale fading of different delays is not correlated
Susceptibility of Large-Scale Statistics
Susceptibility of Small-Scale Statistics
Regeneration of Statistical Channel Model
Model Validation – Qualitative Comparison Measured Power Delay Profiles Simulated Power Delay Profiles
Model Validation – Quantitative Comparision
Conclusions Intra-vehicular wireless sensor networks Provide cost reduction Enable new sensor technologies to be integrated in vehicles Channel characteristics beneath the chassis Large scale statistics: path loss, power variation, General shape of impulse response: modified Saleh. Valenzuela model Small scale statistics Proposed model validated with both qualitative and quantitative comparisons
Publications C. U. Bas and S. C. Ergen, “Ultra-Wideband Channel Model for Intra-Vehicular Wireless Sensor Networks Beneath the Chassis: From Statistical Model to Simulations”, IEEE Transactions on Vehicular Technology, vol. 62, no. 1, pp. 14 -25, January 2013. [pdf | link] U. Demir, C. U. Bas and S. C. Ergen, "Engine Compartment UWB Channel Model for Intra-Vehicular Wireless Sensor Networks", IEEE Transactions on Vehicular Technology, vol. 63, no. 6, pp. 2497 -2505, July 2014. [pdf | link] C. U. Bas and S. C. Ergen, “Ultra-Wideband Channel Model for Intra-Vehicular Wireless Sensor Networks”, IEEE WCNC, April 2012. [pdf | link]
Thank You! QUESTIONS? Umit Bas: cbas@ku. edu. tr Wireless Networks Laboratory: http: //wnl. ku. edu. tr
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