This document specifies the MAC layer protocol for logical channels on the U_m2 interface. This document specifies the following aspects of the logical channel MAC layer:

• Architecture description (section 2)

• Logical channel structure (section 3)

• Burst structure (section 4)

• Burst field definitions (section 5)

• Bearer Service description (section 6)

• Burst Bit Locations (Annex A, Annex B, and Annex C)

This document also provides information on the Galois Field for the Reed Solomon codes (Annex D).

The information necessary to enable an interoperable MAC layer protocol for two-slot TDMA logical channels is provided in this document or referenced in other documents as appropriate. This document assumes the reader has a good working knowledge of the two-slot TDMA document suite identified in [11] and of trunked LMR systems as described in [10].