[STDS-802-16] DCD/UCD message in OFDMA-2048
Dear all,
According to standard (802.16e-2005), the following rules for DCD/UCD
message are defined for OFDMA-2048:
- DCD/UCD are MAC PDU with broadcast (or fragmented broadcast) CID.
- The position and DIUC code of DCD/UCD message are appointed by DL_MAP.
- The uplink/downlink burst profile parameters for each UIUC/DIUC code are
defined and updated by UCD/DCD message (except for the burst profile used by
DL_MAP, which is defined in the downlink frame prefix).
- DCD/UCD may not present in every DL subframe. The maximum time interval
between the transmission of DCD/UCD message will be 10s.
The questions are:
1. When an MS is entering the network, it can decode the downlink frame
prefix because the burst profile is well known. And then it can decode the
DL_MAP because the burst profile is defined in downlink frame prefix. But
the DIUC code used in the DL_MAP are defiend in previous DCD message. How
can MS decode the downlink MAC PDU using the burst profile it has no idea
about? If the MS can not decode the downlink MAC PDU, how can it decode the
DCD, UCD and UL_MAP. And if the UCD and UL_MAP can not be decoded, how to
know initial ranging allocation at MS?
2. Since the DCD/UCD message may not present in every DL subframe, the new
entering MS may waiting for a few frames before it get the first DCD/UCD
message. During this period, it can not decode any other message except for
the DL_MAP/UL_MAP. However, since the DCD/UCD message are treat as generic
MAC PDU, the MS can not recognize them until decode the PDU. So, is there
any method to know the presence and position of DCD/UCD in current DL
subframe?
Thanks.
Best Regards
Jonny