Automated Merging in a Cooperative Adaptive Cruise Control (CACC) System

Cooperative Adaptive Cruise Control (CACC) is a form of cruise control in which a vehicle maintains a constant headway to its preceding vehicle using radar and vehicle-to-vehicle (V2V) communication. Within the Connect & Drive1 project we have implemented and tested a prototype of such a system, with IEEE 802.11p as the enabling communication technology. In this paper we present an extension of our CACC system that allows vehicles to merge inside a platoon of vehicles at a junction, i.e., at a pre-defined location. Initially the merging vehicle and the platoon are outside each other’s communication range and are unaware of each other. Our merging algorithm is fully distributed and uses asynchronous multi-hop communication. Practical testing of our algorithm is planned for May 2011

Stage-dependent Functions of GATA-3 in Lymphocyte Lineage Determination and Type 2 Immunity

All eukaryotic cells of the body carry the same DNA. By using specific sets of genes, cells are able to develop into a wide variety of cell types with specific functions (e.g. muscle, neuronal or immune cells) using the same genetic information. Transcription factors regulate which genes are turned ‘on’, and which genes are ‘off ’, allowing the controlled expression of specific genes at specific times and in a specific cell type. A transcription factor (TF) is a protein that binds to a specific DNA-sequence to control

Evaluating the Impact of Transmission Power on Selecting Tall Vehicles as Best Next Communication Hop

The relatively low height of antennas on communicating vehicles in Vehicular Ad Hoc Networks (VANETs) makes one hop and as well multi-hop Vehicle-to-Vehicle (V2V) communication susceptible to obstruction by other vehicles on the road. When the transmitter or receiver (or both) is a Tall vehi- cle, (i.e., truck), the V2V communication suffer less from these obstructions. The transmission power control is an important feature in the design of (multi- hop) VANET communication algorithms. However, the benefits of choosing a Tall vehicle when transmission power is varied are not yet extensively re- searched. Therefore, the main contribution of this paper is to evaluate the im- pact of transmission power control on the improved V2V communication capa- bilities of tall vehicles. Based on simulations, it is shown that significant bene- fits are observed when a Tall vehicle is selected rather than a Short vehicle as a next V2V communication hop to relay packets. Moreover, the simulation exper- iments show that as the transmission power is increasing, the rate of Tall vehi- cles that are selected as best next V2V communication hop is significantly growing

A Dynamic Geocast Solution to Support Cooperative Adaptive Cruise Control (CACC) Merging

Cooperative Adaptive Cruise Control (CACC) is a type of cruise control in which the speed of a vehicle is controlled based on wireless communication between vehicles. In this paper we tackle the communication needed in case of fully automatic CACC merging at a junction. The first contribution of our paper is to show that to target the vehicles involved we need a special kind of geocast that takes both the geographical location and the dynamics (speed, acceleration) of a vehicle into account. The second contribution is to give a first approach to such a geocast solution. The resulting geocast protocol is able to target multiple destination sets that are geographically dispersed and that are persistent in time. This paper does not yet include an analysis of the protocol, but analyses by means of simulation and real-world testing have already been planned

Constrained Geocast to Support Cooperative Adaptive Cruise Control (CACC) Merging

In this paper we introduce a new geocasting concept to target vehicles based on where they will be in the direct future, in stead of their current position. We refer to this concept as constrained geocast. This may be useful in situations where vehicles have interdependencies based on (future) maneuvers. We have developed a first version of such a protocol in the context of an automated merging application, and tested it using simulations. Results show that the protocol is able to meet the requirements of such applications. Compared to a\ud common geo-broadcast protocol this protocol becomes more reliable as road traffic densities increase, but in other aspects the performance is so far lacking. Based on our experiences with implementing the protocol however we see plenty of room for further improvement

Proof of Node Densities

In this paper we present an analytical model accurately describing the forwarding behaviour of a multi-hop broadcast protocol. Our model covers the scenario in which a message is forwarded over a straight road and inter-node distances are distributed exponentially. Intermediate forwarders draw a small random delay before forwarding a message such as is done in flooding protocols to avoid the broadcast storm problem. The analytical model presented in this chapter focuses on having a message forwarded a specific distance. For a given forwarding distance and a given node density our model analysis is able to capture the full distribution of \emph{(i)} the end-to-end delay to have the message forwarded the entire distance, \emph{(ii)} the required number of hops to have the message forwarded the entire distance, \emph{(iii)} the position of each intermediate forwarder, \emph{(iv)} the success probability of each hop, \emph{(v)} the length of each hop, and \emph{(vi)} the delay of each hop. The first three metrics are calculated assuming that the message is successfully forwarded the entire forwarding distance. The model provides the results in terms of insightful, fast-to-evaluate closed-form expressions. The model has been validated by extensive simulations: modelling results stayed within typically 10\%, depending on the source-to-sink distance and the node density