Stationary units for V2X = RSU

Our RSU (road-side Unit) units are designed to receive V2X standard messages from vehicles and also to send messages to vehicles. They are based on UCU 5.0 units. We offer them in two versions:

• Unit for installation on public lighting  or traffic light columns .
• Unit for installation in distributors.

General properties of the RSU unit

The RSU unit has the following functions:

• Broadcasting CAM messages.
• Receiving CAM messages and aggregating them into short and long term operation statistics.
• Support of forwarding messages as per the Geonet protocol.
• Broadcasting and receiving DENM messages including their generation.
• Broadcasting and receiving IVI messages – the source is typically C-ITS Back Office.
• When connected with an intersection controller unit, it uses MAP messages to broadcast a map of the intersection (stored in the unit or in the controller) and SPT messages to broadcast a signal plan.
• ES preference via CAM messages when the unit is connected to a controller unit.
• MPT or ES preference via SRM and SSM messages when the unit is connected to a controller unit. We do not recommend MPT preference via CMA messages – there is no feedback channel for vehicles.
• Secure communication support (integrated HSM module).
• Possibility of connection to C-ITS BackOffice – by using an embedded LTE modem or cable connection.

Units for intersections

Example

The units that are installed on a column are the “all in one” type and they constitute one mechanical set containing the unit itself, antennas and all the needed converters so that their installation and connection to a controller unit are as simple as possible. If possible these units are placed in the middle of an intersection to cover all its parts with signal. The unit is equipped with high performance antennas and if needed also with a communication adapter to ensure fast communication with an intersection controller unit (ethernet, standard RS 485).

Another communication channel can be provided by a connection to a central server C-ITS Back Office (C-ITS or just BO) via a data connection of the controller unit or via an embedded LTE modem. Thanks to the communication with BO the unit informs passing vehicles about exceptional traffic situation via the V2X technology.

When setting up preference, it is possible to connect the RSU to a controller in such a way that it is compatible  with an already existing preference system to prevent the need of changing the controller SW. By using RS-485 it is possible to use the existing radio modem – controller protocol for RSU – controller communication and thus to replace the just-radio way. Modern V2X will be used without any changes for drivers. We used this procedure to replace the former preference system on 80 intersections in Brno. During a bidirectional communication test in Ostrava, we proved that it is possible to replace the in use system in Ostrava with V2X without changing the controller SW.

Properties of RSU units for intersections

As stated, units are placed on a column in the height of 4-5 m  to reach maximum reach over the intersection.

Setup of RSU units at intersections

We perform the initial setup during installation. This mainly includes configuring:

• IP address of the unit via LTE connection.
• Identification of unit designation
• Unit position via a CAM message
• Map of the intersection, used in MAP messages.
• ES preference zones adjustable by the supplied SW

Units for highways and roadways

RSU unit on the D1 highway

In the demanding highway environment, we offer the option of installing units in distributors. Antennas are brought out independently on a boom. The maximum distance between the distributor and the antennas is 6 meters so the antennas can be placed high enough to provide wide reach of the V2X antennas.

The typical task of these units is transferring messages from C-ITS Back Office to vehicles via V2X but they can also work independently (e.g. collecting traffic data). An embedded LTE modem is usually used to connect to BO but Ethernet cable connectivity or optical connection can be used. As they are placed in converters, the units can be equipped with backup batteries to ensure uninterrupted operation. Units can also be equipped with Wi-Fi connection to provide easier configuration.

In the view of the low ratio of vehicles with V2X, RSU units can be equipped with Wi-Fi + Bluetooth detectors which provide traffic information by detecting mobile phones in vehicles.

We supplied 24 RSU for the D1 highway in cooperation with the Cross Zlín company as a part of the C-ROADS project.

Properties of the UCU 5.0I-LWVG unit