Replacement of LPD by EPD for IEEE 1609 WSMP communication

18. March 2015

In IEEE 1609 WG the motion to replace LPD by EPD for WSMP communications was approved.

Without this move, 5,9 GHz DSRC would have become a small "island" in the networked world that performed this move to EPD already almost completely for the wired networks. Beside achieving more compact packets (WSMP / FNTP), other benefits are given, e.g. VLANs are simplified, and cost of components will be reduced. As some chip vendors likely already developed chips where the LPD is "burned in silicon" they face some initial cost now to redesign their chips. With more "traditional" designs, the move can be implemented with a simple software upgrade. Such software upgrades were already done by various vendors to proof the feasibility of this approach.

A similar approach was prepared at ISO on 31. October 2014, where TC204 approved Resolution 1072:

ISO/TC 204 resolves to support a change from LPD to EPD in the 802.11 specifications for 5.9 GHz frequency bands.

and further on by TC204 WG16 in a decision at the Pisa meeting in February 2015:

To use the periodic revision of ISO 21215:2010 "Intelligent transport systems - Communications access for land mobiles (CALM) - M5" to implement the TC resolution 1072.

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