RFWiMAX Channel Descriptors: UCD, UIUC, DCD, and DIUC Explained
Advertisement
This document explains the WiMAX channel descriptors: Uplink Channel Descriptor (UCD), Uplink Interval Usage Code (UIUC), Downlink Channel Descriptor (DCD), and Downlink Interval Usage Code (DIUC). It details various fields used within these descriptors as per the IEEE 802.16 fixed WiMAX standard’s MAC layer specifications.
WiMAX UCD and DCD: Uplink and Downlink Channel Descriptors
These channel descriptors convey modulation and coding rate information for data bursts. Specifically:
- UCD/UIUC: Describe the modulation and coding rate information for uplink burst profiles.
- DCD/DIUC: Describe the modulation and coding rate information for downlink burst profiles.
UCD and DCD Fields Comparison
Here’s a comparison of key fields found in the UCD and DCD:
| WiMAX UCD Fields | WiMAX DCD Fields |
|---|---|
| Generic MAC Header (6 bytes) | Generic MAC Header (6 bytes) |
| UCD Type (8 bits) | DCD Type (8 bits) |
| CCC (8 bits) | DL channel ID (8 bits) |
| Ranging Back off start (8 bits) | CCC (8 bits) |
| Ranging Back off End (8 bits) | Base station EIRP |
| Request Back Off Start (8 bits) | Request Back Off End (8 bits) |
| downlink center frequency | BS ID |
| Contention based reservation time out | Contention ranging request opportunity size |
| Frame duration code | MAC version |
| Contention ranging request burst size | frame number |
| Uplink center frequency | |
| CRC | CRC (4 bytes) |
WiMAX UIUC: Uplink Interval Usage Code
The following table lists common UIUC values and their corresponding usage or function:
| UIUC Value | Usage/Function |
|---|---|
| 0 | Reserved |
| 1 | Initial ranging |
| 2 | REQ Region Full |
| 3 | REQ region focused |
| 4 | Focused contention IE |
| 5-12 | UCD Burst profiles |
| 13 | Subchannelization network entry |
| 14 | End of Map |
| 15 | Extended UIUC table |
WiMAX DIUC: Downlink Interval Usage Code
The following table lists common DIUC values and their corresponding usage or function:
| DIUC Value | Usage/Function |
|---|---|
| 0 | STC Zone |
| 1-11 | DCD Burst profiles |
| 12 | Reserved |
| 13 | Gap |
| 14 | End of Map |
| 15 | Extended DIUC table |
UCD and DCD Burst Profile Encoding (OFDM)
-
UCD burst profile encoding for OFDM:
{ FEC code rate(TLV format), DIUC mandatory exit threshold, DIUC min. entry threshold, TCS_enable} -
DCD burst profile encoding for OFDM:
{FEC code rate, DIUC mandatory exit threshold, DIUC min. entry threshold, TCS_enable}
Where:
-
FEC code type =
{150,1,FEC_value} -
FEC_value = 0 for BPSK 1/2, 1 for QPSK 1/2, 2 for QPSK 3/4, 3 for 16QAM 1/2, 4 for 16QAM 3/4, 5 for 64QAM 2/3, 6 for 64QAM 3/4, and so on.
