Research Project: Intra-Vehicular Wireless Sensor Networks
Loading...
Contributors
Funders
ID
EC.00014
Authors
Ergen, Sinem Çöleri
Faculty Member
Publications
Optimal power control, rate adaptation, and scheduling for uwb-based intravehicular wireless sensor networks
(Institute of Electrical and Electronics Engineers (IEEE), 2013) Ergen, Sinem Çöleri; Şadi, Yalçın; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
The intravehicular wireless sensor network (IVWSN) is a promising new research area that can provide part cost, assembly, maintenance savings, and fuel efficiency through the elimination of the wires and enables new sensor technologies to be integrated into vehicles, which would otherwise be impossible using wired means such as Intelligent Tire. The close interaction of communication with control systems, strict reliability, energy efficiency, and delay requirements in such a harsh environment that contains a large number of reflectors that operate at extreme temperatures are distinguishing properties of this network. In this paper, we investigate optimal power control, rate adaptation, and scheduling for an ultrawideband-based IVWSN for one-electronic-control-unit (ECU) and multiple-ECU cases. For the one-ECU case, we show that the optimal rate and power allocation is independent of the optimal scheduling algorithm. We prove the NP-hardness of the scheduling problem and formulate the optimal solution as a mixed-integer linear programming (MILP) problem. We then propose a 2-approximation algorithm, which is the smallest period into the shortest subframe first (SSF) algorithm. For the multiple-ECU case, where the concurrent transmission of links is possible, we formulate the optimal power control as a geometric-programming problem and optimal scheduling problem as an MILP problem where the number of variables is exponential in the number of links. We then propose a heuristic algorithm-the maximum-utility-based concurrency allowance algorithm-based on the idea of significantly improving the performance of the SSF algorithm in the existence of multiple ECUs by determining the sets of maximum utility.
Ultra-wideband channel model for intra-vehicular wireless sensor networks beneath the chassis: from statistical model to simulations
(Institute of Electrical and Electronics Engineers (IEEE), 2013) Ergen, Sinem Çöleri; Baş, Celalettin Ümit; Department of Electrical and Electronics Engineering; Yes; College of Engineering
Intra-vehicular wireless sensor networks (IVWSNs) are a promising new research area that can provide part cost, assembly, maintenance savings, and fuel efficiency through the elimination of the wires, and enable new sensor technologies to be integrated into vehicles, which would otherwise be impossible using wired means, such as intelligent tires. The most suitable technology that can meet the high reliability requirement of vehicle control systems and the strict energy efficiency requirement of the sensor nodes in such harsh environment containing a large number of metal reflectors at short distance is the ultra-wideband (UWB). However, there are currently no detailed models describing the UWB channel for IVWSNs, making it difficult to design a suitable communication system. We analyze the small-scale and large-scale statistics of the UWB channel beneath the chassis of a vehicle by collecting data at various locations with 81 measurement points per transmitter-receiver pair for different types of vehicles, including the scenarios of turning the engine on and movement on the road. Collecting multiple measurements allows us to both improve the accuracy of the large-scale fading representation and model small-scale fading characteristics. The path-loss exponent around the tires and other locations beneath the chassis are found to be very different, requiring separate models. The power variation around the path loss has lognormal distribution. The clustering phenomenon observed in the averaged power delay profile (PDP) is well characterized by the Saleh-Valenzuela (SV) model. The cluster amplitude and decay rate are formulated as a function of the cluster arrival times using dual-slope linear models. Cluster interarrival times are modeled using Weibull distribution, providing a better fit than the commonly used exponential distribution in the literature, mainly due to the nonrandomness of the local structure of the vehicle. The variations of local PDPs around the small-scale averaged (SSA) PDPs, in decibels, at each delay bin are modeled by Gaussian distribution with variance independent of the value of the delay and distance between the transmitter and the receiver. The analysis of the model parameters for different vehicles and different scenarios demonstrates the robustness of our modeling approach exhibiting small variance in channel parameters for different vehicle types. Finally, the algorithm for generating the channel model is given. The generated PDPs are in good agreement with the experimental profiles, validating our model.
Minimum energy data transmission for wireless networked control systems
(IEEE-Inst Electrical Electronics Engineers Inc, 2014) Ergen, Sinem Çöleri; Şadi, Yalçın; Park, Pangun; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
The communication protocol design for wireless networked control systems brings the additional challenge of providing the guaranteed stability of the closed-loop control system compared to traditional wireless sensor networks. In this paper, we provide a framework for the joint optimization of controller and communication systems encompassing efficient abstractions of both systems. The objective of the optimization problem is to minimize the power consumption of the communication system due to the limited lifetime of the battery-operated wireless nodes. The constraints of the problem are the schedulability and maximum transmit power restrictions of the communication system, and the reliability and delay requirements of the control system to guarantee its stability. The formulation comprises communication system parameters including transmission power, rate and scheduling, and control system parameters including sampling period. The resulting problem is a Mixed-Integer Programming problem. However, analyzing the optimality conditions on the variables of the problem allows us to reduce it to an Integer Programming problem for which we propose an efficient solution method based on its relaxation. Simulations demonstrate that the proposed method performs very close to optimal and much better than the traditional separate design of these systems.
Fast scheduling for delay minimization in UWB wireless networks
(IEEE-inst Electrical Electronics Engineers inc, 2012) Ergen, Sinem Çöleri; Şadi, Yalçın; Department of Electrical and Electronics Engineering; Yes; College of Engineering
We study the optimal scheduling problem for delay minimization subject to traffic demand, transmit power and Signal-to-Noise-plus-interference Ratio (SNIR) constraints in rate-controlled Ultra-Wideband (UWB) wireless networks. We first formulate the Linear Programming (LP) problem where the number of variables is exponential in the number of the links. We then propose the heuristic algorithm called Exclusion Region and Utility Maximization based Column Generation Method (EXUM-CGM) to solve the problem rapidly and efficiently. in EXUM-CGM, we decompose the large scale problem into two sub-problems, Restricted Master Problem (RMP) and Pricing Problem (PP). We adapt the exclusion region concept commonly used in UWB systems to the initialization of the RMP. Since the PP formulation is a non-linear integer programming problem, we propose a heuristic algorithm based on utility maximization. Through the simulations, we show that EXUM-CGM decreases the runtime of the exponential LP problem significantly while achieving very close-to-optimal solutions.
Engine compartment UWB channel model for intravehicular wireless sensor networks
(IEEE-Inst Electrical Electronics Engineers Inc, 2014) Baş, Celalettin Ümit; Demir, Utku; Ergen, Sinem Çöleri; Department of Electrical and Electronics Engineering; Department of Computer Engineering; Graduate School of Sciences and Engineering; Yes; College of Engineering; GRADUATE SCHOOL OF SCIENCES AND ENGINEERING
Intravehicular wireless sensor network (IVWSN) is a cutting edge research topic that delivers cost reduction, assembly, and maintenance efficiency by removing the wiring harnesses within the vehicle and enables the integration of new sensors into the locations inside a vehicle where cable connection is not possible. Providing energy efficiency through the low-duty-cycle operation and high reliability by exploiting the large bandwidth, ultrawideband (UWB) has been determined to be the most appropriate technology for IVWSNs. We investigate the UWB channel model for IVWSNs within the engine compartment of a vehicle by collecting an extensive amount of data for 19 x 19 links for different types and conditions of the vehicle. These include a Fiat Linea with engine off, Fiat Linea with engine on, and Peugeot Bipper with engine off. The path-loss exponent is estimated to be around 3.5 without exhibiting much variation when the engine is turned on and for different types of vehicles. The power variation around the expected path loss has lognormal distribution with zero mean and standard deviation in the range of [5.5, 6.3] dB for different types of vehicles with almost no variation when the engine of the same vehicle is turned on. The clustering phenomenon in the power delay profile (PDP) is well represented by a modified Saleh-Valenzuela (SV) model. The interarrival times of the clusters are modeled using a Weibull distribution. The cluster-amplitude and ray-amplitude decay functions are represented with a dual-slope linear model with breakpoint around 26.6 and 5.5 ns, respectively. The parameters of the Weibull distribution and these dual-slope linear models do not vary significantly for different types and conditions of the vehicle. The variations of the observed PDPs around the SV model is well modeled by independent normal random variables with zero mean and with a variance independent of the delay bin, and the type and condition of the vehicle. We propose a simulation model for the UWB channel within the engine compartment based on these findings and validate it by comparing the received energy and root mean square (RMS) delay spread of the generated and observed PDPs.
