Reducing Message Collisions in Sensing-based Semi-Persistent Scheduling (SPS) by Using Reselection Lookaheads in Cellular V2X

In the C-V2X sidelink Mode 4 communication, the sensing-based semi-persistent scheduling (SPS) implements a message collision avoidance algorithm to cope with the undesirable effects of wireless channel congestion. Still, the current standard mechanism produces high number of packet collisions, which may hinder the high-reliability communications required in future C-V2X applications such as autonomous driving. In this paper, we show that by drastically reducing the uncertainties in the choice of the resource to use for SPS, we can significantly reduce the message collisions in the C-V2X sidelink Mode 4. Specifically, we propose the use of the "lookahead," which contains the next starting resource location in the time-frequency plane. By exchanging the lookahead information piggybacked on the periodic safety message, vehicular user equipments (UEs) can eliminate most message collisions arising from the ignorance of other UEs' internal decisions. Although the proposed scheme would require the inclusion of the lookahead in the control part of the packet, the benefit may outweigh the bandwidth cost, considering the stringent reliability requirement in future C-V2X applications.Comment: Submitted to MDPI Sensor

Stochastic-Based Pattern Recognition Analysis

In this work we review the basic principles of stochastic logic and propose its application to probabilistic-based pattern-recognition analysis. The proposed technique is intrinsically a parallel comparison of input data to various pre-stored categories using Bayesian techniques. We design smart pulse-based stochastic-logic blocks to provide an efficient pattern recognition analysis. The proposed rchitecture is applied to a specific navigation problem. The resulting system is orders of magnitude faster than processor-based solutions

Developing Low Gasoline Particulate Emission Engines Through Improved Fuel Delivery

Particulate emissions are of growing concern due to health impacts. Many urban areas around the world currently have particulate matter levels exceeding the World Health Organisation safe limits. Gasoline engines, especially when equipped with direct injection systems, contribute to this pollution. In recognition of this fact European limits on particulate mass and number are being introduced. A number of ways to meet these new stringent limits have been under investigation. The focus of this paper is on particulate emissions reduction through improvements in fuel delivery. This investigation is part of the author's ongoing particulate research and development that includes optical engine spray and combustion visualisation, CFD method development, engine and vehicle testing with the aim to move particulate emission development upstream in the development process. As part of this work, a spark eroded and a laser drilled injector were fully characterised in a spray vessel under key engine running conditions. Injector nozzle geometries and mass flow data were also measured in great detail. This paper demonstrates using both steady state and transient engine testing that very significant improvements in particulate emissions can be made. Control strategies enabling multiple injections of smaller volumes of fuel per injection are the most promising technology. The MAHLE Flexible ECU (MFE) combined with injector testing allowed early stage development and demonstrated these effects for a number of key engine operating conditions. Most notably it was found that particulate matter emissions could be reduced by 80-90% during the catalyst light off phase. A new approach was developed (MASTER) to simultaneously assess the effects of calibration changes on all emissions to increase testing efficiency and hence get to more optimised solutions faster. This approach was successfully tested on a production engine comparing two injectors achieving 82% reduction in particulate number emissions during the first 200seconds of the NEDC relative to the EU5b baseline. Finally it was found that both fuel properties and injector deposits can have a significant effect on particulate emissions