IEEE 1609-4-2011 pdf download
IEEE 1609-4-2011 pdf download.IEEE Standard for Wireless Access in Vehicular Environments (WAVE)一Multi-channel Operation.
4.3.3 Management plane services
The MLME management services specified in Clause 6 comprise the following:
— Multi-channel synchronization
The MLME uses information derived locally and received over the air to provide a synchronization function with the objective of aligning channel intervals among communicating WAVE devices. The MLME provides the capability to generate Timing Advertisement (TA) frames to distribute system timing information and monitor received TA frames.
— Channel access
The MLME controls the access to specific radio channels in support of communication requests received from the WME.
— Vendor Specific Action frames
The MLME will accept incoming VSA frames and pass them to the WAVE Management Entity; the MLME will also generate VSA frames for transmission at the request of WME.
— Other IEEE 802.11 services
The MLME allows access to IEEE 802.11 services, which may be invoked on a per-channel basis.
— MIB maintenance
The MLME maintains a management information base (MIB) containing configuration and status information.
— Readdressing
The MLME allows device address changes to be triggered in support of pseudonymity.
5. Data plane services
5.1 General
WAVE devices shall communicate outside the context of an IEEE 802. 11 basic service set (i.e., with dotllO(’BEnabled equal true), as specified in IEEE Std 802.1 lp.
An example of a WAVE multi-channel MAC internal architecture is shown in Figure 2. This reference design architecture is used to specify the following transmit operations: channel routing, data queueing and prioritization, and channel coordination; however, actual implementations may depart from this example design. A WAVE MAC entity uses one or more instances of the MAC sublayer entity specified in IEEE Std 802.11. as amended by IEEE Std 802.iip, operating outside the context of a basic service set, with the extensions defined herein. There are two IEEE Std 8O2.Ilp MAC entities in the example design described in this clause: one for the CCH and one for the SCH. Data is prioritized according to access category (directly related to user priority), as indicated by the queues shown in Figure 2, which provide different contention and transmission parameters for different priority data frames. Prioritization is further specified in 5.4.
There are three types of information exchanged on the WAVE medium: management frames, data frames, and control frames. Control frames may be used per IEEE Std 802. 11 and are not addressed in this standard. Management frames used by WAVE enter the data plane at the MAC layer.
5.2.3 Transmit restrictions on CCH and SCH
A WAVE device shall support transmit or receive operations, and it may support both. A WAVE device shall support at least one, and may support more than one, of the following IEEE 802.11 frame types:
— Management frame of type Timing Advertisement
— Management frame of type Action with subtype Vendor Specific Data frame, when carrying a WSM
— Data frame, when carrying an IP packet
This standard does not prohibit the transmission of other frame types. Any of the preceding frame types may be transmitted in either the CCH interval or the SCH interval. Frames carrying IP packets shall not be transmitted on the CCH and may be transmitted on an SC1-I. Supported control and service channels are identified in the M113, with the CCH specified in Annex H. Other frame types may be transmitted on either the CCH or an SCH.
5.3 Channel routing
5.3.1 General
Channel numbers available for use by the device are listed in the MIB attribute ChannelSetTahie. (‘hanne/Set Table shall contain operating classes as specified in IEEE Std 802.1 lp and IEEE P802.1 1 REVmb. The MAC sublayer receives data for transmission from the LLC sublayer in the form of MA-UNITDATA.requests for IP data or MA-UNITDATAX.requests for WSMP data, as illustrated in Figure 5 and Figure 6. IP data and WSMP data are also distinguished by the Ethertype field of the subnetwork access protocol (SNAP) header within the Data field, which is used by the LLC on the receiving side to deliver the data to the proper higher layer protocol.
For WSMs, the channel, transmit power, and data rate are set by higher layers on a per-message basis. For IP datagrams, the channel, transmit power, and data rate to be used are stored in a transmitter profile.
The channel routing for data and management frames is specified in 5.3.2 through 5.3.6.
5.3.2 Overview of data frame transmit operations
Figure 5 illustrates the contents of the MA-UNITDATAX.request from the LLC to the MAC fbr WSMP data. Eihertipe is passed to the MAC in the SNAP header. Channel number, data rate, transmit power level, destination MAC address, and priority are passed to the MAC through parameters in the MAUNITDATAX.request. A similar example for IP data is shown in Figure 6. A transmitting WAVE device shall support WSMP traffic, IP traffic, or both.
