Jack Singh

Routing mechanisms and cross-layer design for Vehicular Ad Hoc Networks: A survey

Vehicular Ad-Hoc Network (VANET) will pave the way to advance automotive safety and occupant convenience. The potential VANET applications present diverse requirements. VANET shows unique characteristics and presents a set of challenges. The proposed VANET applications demand reliable and proficient message dissemination techniques. Routing techniques proposed for Mobile Ad-Hoc Network (MANET) do not cater for the characteristics of VANET. The need for novel routing techniques, exclusively designed for VANET has been recognised. This paper analyses different routing techniques proposed specifically for VANET. Unique characteristics of VANET pose challenges to traditional layered architecture where different layers make independent decisions. Mobility, absence of global view of network, random changes in topology, poor link quality and varied channel conditions have encouraged the paradigm shift to cross-layer approach. In order to optimise the performance of VANET, architectures based on cross-layer approach have been proposed by the researchers. The paper also surveys such cross-layer paradigm based solutions for VANET and concludes with an analytical summary.

SmartVANET: The Case for a Cross-Layer Vehicular Network Architecture

Dedicated Short Range Communication (DSRC) based Vehicular Ad Hoc Network (VANET) provides an opportunity to enable communication-based cooperative safety systems in order to decrease road traumas and improve traffic efficiency. VANET also offers a wide range of commercial and infotainment applications. VANET exhibits unique characteristics that create new challenges. This paper discusses the DSRC technology and its shortcomings in order to achieve reliable content dissemination. To optimise the performance of the vehicular networks, a novel network architecture using the cross-layer paradigm is presented. The architecture is called Smart Vehicular Ad-hoc Network (SmartVANET) architecture. The proposed SmartVANET architecture can support safety, traffic management and commercial applications. The SmartVANET architecture complies with the DSRC channel plan. The architecture divides road into segments and assigns a service channel to each segment. The SmartVANET combines a segment based clustering technique with a hybrid Medium Access Control (MAC) mechanism (termed as the Smart MAC protocol). Using cross-layer integration, SmartVANET also provides a solution for broadcast storm problems and offers scalability. The paper presents the SmartVANET architecture and argues its advantages.

A survey of lower layer technologies for Vehicle-to-Vehicle communication

Vehicle-to-Vehicle (V2V) communication is an evolving research field that has potential to augment safety on our roads. Safety focused V2V communication also offers convenience and commercial applications in order to enhance driving comfort and pleasure. V2V communication demonstrates unique characteristics and consequently reliable network access has become crucial to exploit a wide spectrum of applications. Development of complex networking protocols, ingenious medium access control (MAC) techniques and robust communication technology are the main challenges to reliable and pragmatic V2V communication. This paper provides survey of lower layer technologies proposed for V2V communication and concludes with analytical summary drawn from the survey.

A highly sensitive and ultra low‐power forward body biasing circuit to overcome severe process, voltage and temperature variations and extreme voltage scaling

Summary Dynamic voltage scaling is one of the most popular methods used to reduce energy consumption in todays digital electronic systems. However, addressing process, voltage and temperature variations at subthreshold voltages has become an inevitable procedure. Using a variation-sensitive and ultra low-power design, this paper proposed a novel technique capable of sensing and responding to process, voltage and temperature variations as well as dynamic voltage scaling by providing an appropriate forward body bias so that energy-delay product of the whole system was improved. Theoretical analysis for process variation probability, confirmed by post-layout HSPICE (Synopsys, Inc., Mountain View, CA) simulations for an 8-bit pipelined Kogge–Stone adder, showed that the circuit performance was enhanced in severe variations and extreme voltage scaling situation. For this adder, for example, assuming a voltage scaling from 0.8 to 0.3 V and temperature changes of −15 to 75 °C, the proposed technique brought about a seven times less delay variation, whereas energy-delay product improved by 23% compared with a zero body biased adder. Copyright

A Hybrid TDMA protocol based Ultra-Wide Band for in-car wireless communication

The use of wireless technology for intra-vehicle communication is becoming possible in replacing in-scalable, high weight and high manufacture cost automotive wired networks. Ultra-Wide Band (UWB) is emerging as an ideal alternative for implementing an Intra-Vehicle Wireless Sensor Network (I-VWSN) due to its very high data rate and low power consumption. However, the current IEEE MAC Layer Protocol for UWB, IEEE 802.15.3a using CSMA/CA technique, cannot support real-time requirements for in-vehicle applications. This paper presents a Hybrid TDMA MAC protocol that not only guarantees the stringent latency of in-vehicle sensors information, but also allows the integration of other high consumption bandwidth devices such as passenger entertainment electronics. Each cycle of the protocol is divided into two segments: Static Segment (StS) and Dynamic Segment (DyS). The static segment consists of several equal static slots which are allocated to every node sending data periodically. Meanwhile, the dynamic segment is used for event-trigger or noncritical-time information. The channel during the DyS is competed for by nodes with different priorities.

A very high Q-factor inductor using MEMS technology

This paper presents the design and optimisation of a very high Quality (Q) factor inductor using MEMS technology for 10GHz to 20GHz frequency band. The effects of various parameters of a symmetric inductor structure on the Q-factor and inductance are thoroughly analysed. The inductor has been designed on Silicon-on-Sapphire (SOS) substrate because it offers superior characteristics of low substrate loss due to the high resistivity of the sapphire material and low capacitive coupling to the substrate. It is also been suspended from the substrate in order to reduce the substrate loss and improved the Q factor. Results indicate that a maximum Q factor of 192 for a 1.13nH inductance at 12GHz is achieved after optimising the symmetric inductor.

Design and analysis of film bulk acoustic wave resonator in Ku-band frequency for wireless communication

This paper presents design of a Film Bulk Acoustic Wave Resonators (FBARs) consisting of piezoelectric film, aluminium nitride (AlN) with top and bottom electrodes of ruthenium (Ru). The lumped Butterworth-Van Dyke (BVD) Circuit model is used to investigate the theoretical harmonic response and extraction equivalent circuit of the FBAR. A three-dimensional (3D) Finite Element Method (FEM) is used to evaluate the electro-mechanical performance of the FBAR. The one-dimension (1D) numerical and the 3D FEM simulation results are analysed and compared. The results show that coupling coefficient (k2 eff) up to 7.0% can be obtained with optimised thickness ratio of electrode/piezoelectric layers. A Figure of Merit (FOM) that considers k2 eff and quality (Q) factor is used for comparison. The area of FBAR is 900μm2 and the active filter area size of the FBAR filter is 5400μm2. The FBAR filter is designed for operation in Kuband with centre frequency of 15.5 GHz and fractional bandwidth of 2.6%. The proposed FBAR filter has insertion loss of -2.3dB which will improve the performance of Ku-band transceiver and improve communication range and data rates in Ku-band communication links.

Film Bulk Acoustic Wave Resonator Filter for Ku-Band Applications

The design and analysis of Ku-band ladder-type filters based on film bulk acoustic wave resonator (FBAR) is presented. The proposed FBAR filter has an insertion loss of-3dB, out-of-band rejection of-12dB, centre frequency of 15.5GHz with 3dB bandwidth of 1.0GHz. Based on the characteristics of the FBAR filter, the expected characteristics of FBAR resonators are determined by using the Butterworth Van Dyke (BVD) equivalent circuit.

Design Optimization of Low Power and Low Frequency Vibration Based MEMS Energy Harvester

The development and utilization of different structural materials, optimization of the cantilever geometry and power harvesting circuit are the most commonly methods used to increase the power density of MEMS energy harvester. This paper discusses the cantilever geometry optimization process of low power and low frequency of bimorph MEMS energy harvester. Three piezoelectric materials, ZnO, AlN and PZT are deposited on top and bottom of the cantilever Si substrate. This study focuses on the optimization of the cantilevers length, width, substrate thickness and PZe thickness in order to achieve lower than 600 Hz of resonant frequency. The harvested power for this work is in the range of 0.02 ~ 194.49 nW.

Design and analysis of a 10GHz LC-VCO using MEMS inductor

This paper presents design and analysis of a 10GHz inductance-capacitance (LC)-Voltage-Controlled Oscillators (VCO) implemented with a very high quality (Q) factor on-chip Micro-Electro-Mechanical Systems (MEMS) inductor using 0.25μm silicon-on-sapphire (SOS) technology. A new symmetric topology of suspended MEMS inductor is proposed to reduce the length of the conductor strip and achieve the lowest series resistance in the metal tracks. This MEMS inductor has been suspended above the high resistivity SOS substrate to minimise the substrate loss and therefore, achieve a very high Q-factor inductor. A maximum Q-factor of 191.99 at 11.7GHz and Q-factor of 189 at 10GHz has been achieved for a 1.13nH symmetric MEMS inductor. The proposed inductor has been integrated with a VCO on the same substrate using the Metal layers in SOS technology removing the need for additional bond wire. The 10GHz LC-VCO has achieved a phase noise of -116.27dBc/Hz and -126.19dBc/Hz at 1MHz and 3MHz of offset frequency, respectively. It consumes 4.725mW of power from 2.5V supply voltage while achieving a Figure of Merit (FOM) of -189.5dBc/Hz.