Medium Access Control (MAC) and Physical Layer (PHY) - CISE

4-June-07 P1901_PRO_016_r0
4.4 MAC DELIMITERS
Figure 36: Clock frame timming reference
As described in 4.3, the MAC layer generates two types of MPDUs: regular MPDUs and Channel Estimation
MPDUs. These MPDUs make use of two MAC delimiters:
• Token Announce
• Token
Note: MAC delimiters are processed by the PHY layer as described in 3.3.1.
4.4.1 Token announce
The Token Announce is sent in the initial sequence of every transmission frame. The Token Announce has the
following fields:
- Preamble – 32 bits. The preamble is equal to 0x90471D2D. The preamble is used to distinguish the
different types of control symbols.
- Type – 4 bits. In this case, Type should be ANNOUNCE(3).
- Validity – 12 bits. Maximum number of symbols that will be transmitted in the current transmission
after this Token Announce Symbol. The maximum number that can be used is MAX_TA_VALIDITY
- Access Id – 16 bits. This id must be set to 0x0001.
Submission page 106 UPA-OPERA