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SAE J2735-Draft-Rev28 [issued: 11-10-08]
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This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
3.50 management plane: The collection of functions performed in support of the communication system
operation, but not directly involved in passing application data.
3.51 message: A well structured set of data elements and data frame that can be sent as a unit between
devices to convey some semantic meaning in the context of the applications about which this standard
deals.
3.52 message set: A collection of messages based on the ITS functional-area they pertain to. This DSRC
standard is also a message set.
3.53 message set extender: The concept of a message set extender refers to the process of adding
additional data elements to a common (non-changing) core message in order to extend the basic core
message structure to create messages for specific applications needs.
3.54 metadata: Data that defines and describes other data.
3.55 networking services: The collection of management plane and data plane function at the network
layer and transport layer, supporting WAVE communications.
3.56 Node Configuration data: Definition to be refined by committee. When a map of an intersections is
represented a node configuration data value provided key information regarding how the data vales found
in the map are to be understood.
3.57 notification: An indication of an event of interest, sent to an application.
3.58 OBU to vehicle host interface (OVHI): Interface on the OBU offering access to WAVE capabilities
by other vehicle-based devices.
3.59 offset (phase): Offset is the time lag for the cycle start of a coordinated signal. Quoting from the
FHWA Signal Timing Manual, Chapter 6, Section 6.1 Terminology. (Draft 3 version, development still
underway): “The time relationship between coordinated phases defined reference point and a defined
master reference (master clock or sync pulse)." In other words, a local signal controller setting that
references the start of the green to a common clock so the beginning of green can be coordinated along a
roadway to speed motorist along at a designed speed.
3.60 on-board unit: An On-Board Unit (OBU) is a vehicle mounted DSRC device used to transmit and
receive a variety of message traffic to and from other DSRC devices (other OBUs and RSUs). Among the
message types and applications supported by this process are vehicle safety messages, a primary subject of
this standard, used to exchange information on each vehicle's dynamic movements for coordination and
safety.
3.61 operations: One of three modes, or states, of operation known as Registration, Initialization, and
Operations which DSRC systems operate in. In the Operations mode a link has been established, the link
will have an open socket with which it can conduct operations in the same manner as with any other 802.11
communications session. The lower layers will be managing the switching between the Control Channel
and the Service Channel. When the radio has switched to another channel, it would appear to the
application as a temporary loss of communications.