Advances in Vehicular Networking Technologies Part 11 docx

Advances in Vehicular Networking Technologies 292 navigational aids, vibrotactile stimulation systems that use several vibrators in the shape of a cap (Cassinelli et al. 2006), rings (Amemiya et al. 2004), a vest (Erp et al. 2005), belt (Tan et al. 2003; Heuten et al. 2008), and glove (Zelek et al. 2003) have been proposed. Unfortunately, these tactile approaches require that users learn how to convert stimuli to information. This is not intuitive and requires training since the tactile stimuli employed are basically non-directional. 8. Acknowledgements We thank Dr. Ichiro Kawabuchi for his technical assistance. We also thank Hisashi Sugiyama, the staff of Kyoto City Fire Department, and the staff of the Kyoto Prefectural School for the Visually Impaired for their kind cooperation. This study was supported by Nippon Telegraph and Telephone Corporation and was also partially supported by the sponsorship of the Fire Defence Agency, Japan. 9. References Amemiya, T.; Ando, H. & T. Maeda T. (2005). Virtual force display: Direction guidance using asymmetric acceleration via periodic translational motion, Proceedings of World Haptics Conference, IEEE Computer Society, pp. 619-622. Amemiya, T.; Ando, H. & T. Maeda T. (2008). Lead-Me interface for pulling sensation in hand-held devices, ACM Transactions on Applied Perception, Vol. 5, No. 3, pp. 1-17. Amemiya, T. & Maeda, T. (2008). Asymmetric oscillation distorts the perceived heaviness of handheld objects, IEEE Transactions on Haptics, Vol. 1, No. 1, pp. 9-18. Amemiya, T. & Maeda, T. (2009). Directional force sensation by asymmetric oscillation from a double-layer slider-crank mechanism, Journal Computing Information Science in Engineering, Vol. 9, No. 1, 011001. Amemiya, T.; Maeda, T. & Ando, H. (2009). Location-free Haptic Interaction for Large-Area Social Applications, Personal and Ubiquitous Computing, Vol. 13, No. 5, pp. 379-386, Springer. Amemiya, T. & Sugiyama, H. (2009). Haptic Handheld Wayfinder with Pseudo-Attraction Force for Pedestrians with Visual Impairments, Proceedings of 11th ACM Conference on Computers and Accessibility (ASSETS 2009), Pittsburgh, PA, pp. 107-114. Amemiya, T. & Sugiyama, H. (2010). Orienting Kinesthetically: A Haptic Handheld Wayfinder for People with Visual Impairments, ACM Transactions on Accessible Computing, Vol. 3, No. 2, pp. 1-23. Amemiya, T.; Yamashita, J.; Hirota, K. & Hirose, M. (2004). Virtual Leading Blocks for the Deaf-Blind: A Real-Time Way-Finder by Verbal-Nonverbal Hybrid Interface and High-Density RFID Tag Space, In Proc. of IEEE Virtual Reality Conference 2004 (VR 2004), pp. 165-172. Bradley, A. & Dunlop, D. (2005). An experimental investigation into wayfinding directions for visually impaired people, Personal Ubiquitous Computing, Vol. 9, No. 6, pp. 395- 403. Cassinelli, A.; Reynolds, C. & Ishikawa, M. (2006). Augmenting spatial awareness with haptic radar. In Proc. International Conference on Wearable Computing. IEEE Computer Society, pp. 61-64. Kinesthetic Cues that Lead the Way 293 Coren, S.; Ward, L. M. & Enns, J. T. (2003). Sensation and Perception. John Wiley and Sons, Inc. Crandall, W.; Brabyn, J.; Bentzen, B. & Myers, L. (1999). Remote infrared signage evaluation for transit stations and intersections. Journal of Rehabilitation Research and Development Vol. 36, pp. 341-355. Enriquez, M. & MacLean, K. (2008). The role of choice in longitudinal recall of meaningful tactile signals. In Proc. of 16th IEEE Symposium on Haptic interfaces for virtual environment and teleoperator systems. pp. 49-56. Erp, J. B. F. V.; Veen, H. A. H. C. V.; Jansen, C. & Dobbins, T. (2005). Waypoint navigation with a vibrotactile waist belt. ACM Transactions on Applied Perception, Vol. 2, No. 2, pp. 106-117. Foulke, E. (1996). The roles of perception and cognition in controlling the mobility task. International Symposium on Orientation and Mobility. Golledge, R. G. (1992). Place recognition and wayfinding: making sense of space. Geoforum Vol. 23, No. 2, pp. 199-214. Gurocak, H.; Jayaram, S.; Parrish, B. & Jayaram U. (2003). Weight sensation in virtual environments using a haptic device with air jets, Journal of Computing and Information Science in Engineering, Vol. 3, No. 2. ASME, pp. 130-135. Hayward, V. (2008). A Brief Taxonomy of Tactile Illusions and Demonstrations That Can Be Done In a Hardware Store, Brain Research Bulletin, Vol. 75, pp. 742-752. Heuten, W.; Henze, N.; Boll, S. & Pielot, M. (2008). Tactile wayfinder: a non-visual support system for wayfinding. In NordiCHI. ACM International Conference Proceeding Series, Vol. 358. ACM Press, pp. 172-181. Hirose, M.; Hirota, K.; Ogi, T.; Yano, H.; Kakehi, N.; Saito, M. & Nakashige, M. (2001). HapticGEAR: The Development of a Wearable Force Display System for Immersive Projection Displays, Proceedings of Virtual Reality 2001 Conference, pp. 123–130. Hoshi ,T.; Takahashi, M.; Iwamoto, T. & Shinoda, H. (2010). Noncontact Tactile Display Based on Radiation Pressure of Airborne Ultrasound, IEEE Transactions on Haptics, Vol. 3, No .3, pp. 155-165. Loomis, J.; Marston, J.; Golledge, R. & Klatzky, R. (2005). Personal guidance system for people with visual impairment: A comparison of spatial displays for route guidance. Journal of Visual Impairment and Blindness Vol. 8, No. 5, pp. 61-64. Massie, T. & Salisbury, J. K. (1994). The phantom haptic interface: A device for probing virtual objects, Proceedings of the ASME Winter Annual Meeting, Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems, Vol. 55-1, pp. 295-300. Nakamura, N. & Fukui, Y. (2007). Development of Fingertip Type Non-grounding Force Feedback Display, Proceedings of World Haptics Conference 2007, pp. 582-583. Pielot, M., Henze, N., Heuten, W., & Boll, S. (2008). Evaluation of continuous direction encoding with tactile belts. In Proc. the 3rd international workshop on Haptic and Audio Interaction Design, Springer, LNCS, pp. 1-10. Richard, C. & Cutkosky, M. (1997). Contact Force Perception with an Ungrounded Haptic Interface, Proceedings of the ASME Dynamic Systems and Control Division, pp. 181– 187. Ross, D. & Blasch, B. (2000). Wearable interfaces for orientation and wayfinding. In Proc. ACM Conference on Assistive Technologies. ACM Press, pp. 193-200. Advances in Vehicular Networking Technologies 294 Suzuki, Y.; Kobayashi, M. & Ishibashi, S. (2002). Design of force feedback utilizing air pressure toward untethered human interface, Proceedings of CHI ’02 Extended Abstracts on Human Factors in Computing Systems. ACM Press, 2002, pp. 808-809. Swindells, C.; Unden, A. & Sang, T. (2003). TorqueBAR: an ngrounded haptic feedback device. Proceedings of the 5th international conference on multimodal interfaces. ACM Press, pp. 52-59. Tan, H. Z.; Gray, R., Young, J. J. & Traylor, R. (2003). A haptic back display for attentional and directional cueing. Haptics-e: The Electronic Journal of Haptics Research Vol. 3, No. 1. Tanaka, Y.; Masataka, S.; Yuka, K.; Fukui, Y.; Yamashita, J. & Nakamura, N. (2001). Mobile torque display and haptic characteristics of human palm. Proceedings of 11th international conference on augmented tele-existence, pp. 115-120. Wilson, J.; Walker, B.; Lindsay, J.; Cambias, C. & Dellaert, F. (2007). Swan: System for wearable audio navigation. In Proc. International Conference on Wearable Computing. IEEE Computer Society, pp. 91-98. Yano, H.; Yoshie, M. & Iwata, H. (2003). Development of a nongrounded haptic interface using the gyro effect, Proceedings of 11th international symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems. IEEE Computer Society, pp. 32-39. Zelek, J. S.; Bromley, S.; Asmar, D. & Thompson, D. (2003). A haptic glove as a tactile-vision sensory substitution for wayfinding. Journal of Visual Impairment and Blindness Vol. 97, No. 10, pp. 621-632. Part 2 Transmission Technologies and Propagation 16 Technological Trends of Antennas in Cars John R. Ojha, René Marklein and Ian Widjaja Germany 1. Introduction Antennas have become a commonplace in automotive applications. These are broadly classified as wire and patch antennas which are used in cars for inter-vehicle communication. Besides its use in the automotive sector, these antennas are also used as arrays in the aviation sector e.g. fuselage integrated microstrip phased antenna arrays. These wire and patch antennas can either be modeled analytically e.g. using the Green’s function, derived from Eigen functions or numerically using various approaches e.g. MoM, FDTD, FEM etc. Besides the common usage of wire and patch antennas of various shapes, integrated antennas are also widely used. Antennas starting from the traditional monopole antenna followed by patch antennas on car roof tops and mesh antennas on car windscreens will be discussed in this chapter. 2. Figures of merit This section lists and explains some salient figures of merit of antennas. The input impedance and the radiated fields (near and far) are termed as the primary figures of merit since they form the basis on which other secondary figures of merit such as VSWR, bandwidth, and directivity etc. are determined. Section 2.1 elaborates on the primary figures of merit viz. input impedance. Section 2.2 explains some secondary figures of merit which are obtained from the input impedance. The theory of how the effective radiating power is calculated from the far-field gain patterns is explained in section 2.3. 2.1 Input impedance The input impedance Z in is defined as the impedance presented by an antenna at its input terminals a – b, as shown in Fig. 1. In other words, the input impedance of an antenna is the ratio of the voltage to the current or the ratio of the electric to the magnetic field measured at the input terminals (feeding point). The input impedance of an antenna is expressed in terms of its real and imaginary parts as in in in ZRjX,=+ (1) where Z in is the antenna impedance at the input terminals a – b, R in is the antenna resistance at the input terminals a – b, and X in is the antenna reactance at the input terminals a – b. Advances in Vehicular Networking Technologies 298 Fig. 1. Block diagram of a transmitting antenna The imaginary part X in of the input impedance represents the power stored in the near field region of the antenna. The resistive part R in of the input impedance consists of two components, the radiation resistance R r and the loss resistance R l . The power associated with the radiation resistance R r is the power actually radiated by the antenna and the loss resistance R l represents the dielectric or conducting losses resulting in power dissipation. The input impedance is of great importance in wire and patch antennas and is therefore discussed here. The input impedance is used as a foreboding of unwanted radiation for EMC related aspects especially in the automotive sector. However, in the case of antennas, the input impedance with the source impedance is used as an intermediate parameter for determining the S11 parameter, return loss, Voltage Standing Wave Ratio (VSWR), and bandwidth. This is explained in more detail in section 2.2, where the matching characteristics of a patch antenna and its bandwidth are explained. 2.2 Reflection coefficient / S11 / VSWR / return loss Antennas are commonly used in various type of smart antenna systems. In order for any given antenna to operate efficiently, the maximum transfer of power must take place between the feeding system and the antenna. Maximum power transfer can take place only when the input impedance of the antenna (Z in ) is matched to that of the feeding source impedance (Z S ). According to the maximum power transfer theorem, maximum power can be transferred only if the impedance of the source is a complex conjugate of the impedance of the antenna under consideration and vice-versa. If this condition for matching is not satisfied, then some of the power may be reflected back. This is expressed as 1|| , 1|| VSWR + Γ = − Γ (2) with , rinS iinS VZZ VZZ − Γ= = + (3) Technological Trends of Antennas in Cars 299 where Γ is called the reflection coefficient, V r is the amplitude of the reflected wave, and V i is the amplitude of the incident wave. The VSWR is basically a measure of the impedance mismatch between the feeding system and the antenna. The higher the VSWR, the greater is the mismatch. The minimum possible value of VSWR is unity and this corresponds to a perfect match. The return losses (RL), obtained from equations (2) and (3), indicate the amount of power that is transferred to the load or the amount of power reflected back. In the case of a microstrip-line-fed antenna, where the source and the transmission line characteristic impedance or the transmission line and the antenna edge impedance do not match, waves are reflected. The superposition of the incident and reflected waves leads to the formation of standing waves. Hence the RL is a parameter similar to the VSWR to indicate how well the matching is between the feeding system, the transmission lines, and the antenna. The RL is 20lo g ||RL = −Γ (dB). (4) To obtain perfect matching between the feeding system and the antenna, Γ = 0 is required and therefore, from equation (4), RL = infinity. In such a case no power is reflected back. Similarly at Γ = 1, RL = 0 dB, implies that all incident power is reflected. For practical applications, a VSWR of 2 is acceptable and this corresponds to a return loss of 9.54 dB. Usually return losses ranging from 10 dB to 12 dB are acceptable. The bandwidth could be defined in terms of its Voltage Standing Wave Ratio (VSWR) or input impedance variation with frequency. The VSWR or impedance bandwidth of an antenna is defined as the frequency range over which it is matched with that of the feed line within specified limits. The BW of an antenna is inversely proportional to its quality factor Q and is expressed as 1VSWR BW QVSWR − = . (5) The bandwidth is usually specified as the frequency range over which the VSWR is less than 2 (which corresponds to a return loss of 9.5 dB or 11 % reflected power). Sometimes for stringent applications, the VSWR requirement is specified to be less than 1.5 (which corresponds to a return loss of 14 dB or 4 % reflected power). In the case of a patch antenna, the input impedance with the source impedance is used as an intermediate parameter for determining the S11 parameter (a measure of the reflection coefficient Γ), return loss, Voltage Standing Wave Ratio (VSWR), and bandwidth. The return loss is expressed in dB in terms of S11 as the negation of the return loss. The bandwidth can also be defined in terms of the antenna’s radiation parameters such as gain, half power beam width, and side-lobe levels within specified limits. 2.3 Effective radiating power For every other antenna, the directivity is defined as the ratio of the radiation intensity in a given direction from the antenna to the radiation intensity U 0 averaged over all directions. If the direction is not specified, the direction of maximum radiation intensity is implied. Hence mathematically the directivity is max max 0 4 orad UU D UP π == , (6) Advances in Vehicular Networking Technologies 300 where max , rad UP are the maximum radiation intensity and total radiated power, expressed in Watts / solid angle and Watts respectively. The antenna gain is directly associated with the directivity of an antenna and is therefore associated with only the main lobe. The term K is the radiation efficiency expressed in terms of the conduction efficiency K c and dielectric efficiency K d as cd KKK= , (7) Gain and directivity extraction are based on the source power. Let us assume that P t is the source power and P v are some losses in the structure (e.g. dielectric losses), then a power P t P r =P t - P v will be radiated. The directivity (as compared to an isotropic point source) is then defined as D = 4πR2 * (S s /P r ), (8) where S s = (1 /2) F0 (|E 2 E |2 / Z )+ ϑφ Z F0 denotes the wave impedance of the surrounding medium. From the equation the gain is extracted from the directivity as GKD = ⋅ , (9) where G is the gain and D is the directivity. (For an antenna with 100% efficiency, K = 1.) The far field gain is determined from the electric far-field components E θ and E φ and the source power. The electric field components E θ and E φ are calculated from the surface electric current densities. The effective radiating power is extracted from the gain by removing the effect of the losses in the form of metallic or /and dielectric losses. Effective Radiating Power Gain Power loss=− (10) 3. Numerical approaches for determining figures of merit The numerical analysis e.g. MoM can be carried out either in the spectral or in the time domain. A patch antenna comprising metallic and dielectric parts with a feeding pin or microstrip line is solved using the traditional MoM by decomposing the antenna as • discretized surface parts • wire parts • attachment node of the wire to the surface element. Metallic surfaces contain different basis functions as shown in Fig. 2. The MoM uses surface currents to model a patch antenna. In the case of ideal conductors, the boundary condition of E tan = 0 is applied. The most commonly used basis functions for line currents through wires are stair case functions, triangular basis functions, or sine functions. The MoM code uses triangular basis functions. In contrast to wires, two-dimensional basis functions are employed for surfaces. The current density vectors have two-directional components along the surface. Figure 2 shows the overlapping of so-called hat functions on triangular patches. An integral equation is formulated for the unknown currents on the microstrip patches, the feeding wire / feeding transmission line, and their images with respect to the ground plane. The integral equations are transformed into algebraic equations that can be easily solved using a [...]... not exceed 2 since the aperture efficiency of a single patch begins to drop, as W/L increases beyond 2 310 Advances in Vehicular Networking Technologies - To increase bandwidth, increase the substrate height and/or decrease the substrate permittivity (this will also affect resonant frequency and the impedance matching) To increase the input impedance, decrease the width of the feed lines attached... cross-over point The use of electrically thick substrates in designs will have degraded matching due to increased feed pin inductance Increasing the patch’s diameter will decrease the resonant frequency and vice versa Increasing the substrate height will increase the bandwidth, but will decrease the resonant frequency slightly Increasing the substrate height will also result in a more inductive reactance... include more and more antennas into their vehicle designs Requirements include FM/AM antennas, TV antennas, etc Aesthetically speaking, this is a problem that can only be overcome by including such antennas into vehicle designs in unobtrusive ways A prominent modern development is to include these antennas into the windscreens of a vehicle These windscreens include multiple layers of glass and wiring... layers of glass • Coupling between closely spaced antenna elements • Curved/rotated windscreens • Multiple windscreens 312 Advances in Vehicular Networking Technologies Using the aforesaid approach only the metallic parts need to be meshed and not the dielectric parts of the windscreen elements of a car Alternately the dielectric material i.e the windscreen can be modelled using various methods e.g... layer coding with inter-frame interleaving, joint physical/link layer coding clearly shows an improvement of performance Note that for joint PHY/LL coding both interleavers π 1 and π 2 are synchronized, so that the overall delay that is experienced due to interleaving is equivalent to the maximum of the delays introduced by π 1 and π 2 (in our case not more than 200 ms) Fig 4 PER vs Es/No with joint physical... Vehicular Networking Technologies Fig 5 shows the characteristics of a traditional monopole antenna on an infinite ground plane The far-field gain, antenna efficiency, and matching characteristics change with change in location of a monopole antenna in positions A, B, and C shown in Fig 7 Fig 8 shows variation in the far- field gain patterns for change in the antenna location There is also a variation in. .. Assuming interleaving windows longer than a 319 Link Layer Coding for DVB-S2 Interactive Satellite Services to Trains PA fade duration (thus, spreading the erasures on a wider duration), the PHY layer decoder deals with a combination of an erasure channel with AWGN (EC-AWGN) This state spans over a whole interleaver window As an illustration the overall channel model is depicted in Figure 5 Denoting... layer) through a long inter-frame interleaver Moreover, a further, simplified model for the railroad satellite channel is introduced to give a basic understanding of the performance for the different solutions Concluding remarks follow in Section V 314 Advances in Vehicular Networking Technologies 2 Railroad satellite channel model An appropriate model for the propagation channel in a railway environment... different interleaving depths Overall spectral efficiency of 0.5 bps/Hz Speed of 30km/h (left) and 150km/h (right) 318 Advances in Vehicular Networking Technologies on the right) The best results can be achieved by using no physical interleaver at all In this case the LL code is able to overcome the errorfloor at both speeds and ensures a steep slope of the PER curve in the waterfall region Compared to plain... To increase the bandwidth, increase the wire thickness (Note that changes in wire thickness will have a small effect on the operating frequency of the antenna This should be corrected for by adjusting the length according to the previous guideline) To decrease the impedance variation versus frequency, increase the element diameter Fig 6 Monopole antenna (inclined) mounted on a car 304 Advances in Vehicular . the input terminals a – b, and X in is the antenna reactance at the input terminals a – b. Advances in Vehicular Networking Technologies 298 Fig. 1. Block diagram of a transmitting. exceed 2 since the aperture efficiency of a single patch begins to drop, as W/L increases beyond 2. Advances in Vehicular Networking Technologies 310 - To increase bandwidth, increase the. The input impedance of an antenna is expressed in terms of its real and imaginary parts as in in in ZRjX,=+ (1) where Z in is the antenna impedance at the input terminals a – b, R in