Annex B: Example of the Downlink Channel Descriptor (DCD) Message
In Chapter 9, were given the global parts of a DCD message, a MAC management message that describes the PHY characteristics of the downlink channel. This example of a DCD message contains the descriptions of two downlink burst profiles respectively identified by DIUC 0101 (hexadecimal: 5) and DIUC 1010 (hexadecimal: A). In this Annex the full details of this message are given, using OFDM (WiMAX) PHYsical interface specifications.
The construction of this message is based on Tables 233 and 358 and, more generally, on Section 11.4 of the IEEE 802.16-2004 specification. Some of the numerical values chosen may not be completely based on practical considerations (e.g. BSID, whose definition is not exhaustive in the standard). 802.16e added new parameters to the DCD message (mainly for the handover process) that are not included in this example.
| Field content | Field length | Field name | Description |
|---|---|---|---|
| 01 | 8b (fixed) | MAC Management Message Type | 01 is the value for DCD |
| 04 | 8b (fixed) | Downlink Channel ID | Arbitrarily chosen by the BS |
| 01 | 8b (fixed) | Configuration Change Count | Indicates a change versus previous DCD message (01 is an assumption) |
Start of the Downlink Burst Profile Description for DIUC value = 0101 (hexadecimal: 5). This part is TLV encoded.
| 01 | 8b (fixed) | Downlink_Burst_Profile Type | Downlink_Burst_Profile Indicator |
| 44 (decimal: 67) | 8b (fixed) | Downlink_Burst_Profile Length | 67 bytes for the overal Downlink_Burst_Profile of DIUC = 0101 |
| 0 | 4b (fixed) | Reserved | Set to zero |
| 05 | 4b (fixed) | DIUC value | This value of DIUC will be associated with the Downlink Burst Profile and Thresholds defined in the following |
Open table as spreadsheet Start of Channel Encodings values for DIUC value = 0101 (hexadecimal: 5). This part is TLV encoded.
| 01 | 1 byte (fixed) | Type for Downlink_Burst_Profile encoding | The number of bytes in the overall object, including embedded TLV items |
| 01 | 1 byte | Length for Downlink_Burst_Profile encoding | See Rule for TLV Length |
| 44 (decimal: 67) | 1 byte | Value for Downlink_Burst_Profile encoding | 67 bytes for the overall Downlink_Burst_Profile of DIUC = 0101 |
| 02 | 1 byte (fixed) | Type for BS EIRP encoding | The BS Transmitted Power (effective isotropic radiated power) |
| 01 | 1 byte | Length for BS EIRP encoding | See Rule for TVL Length |
| 1E | 1 byte | Value for BS EIRP encoding | Signed in units of 1 dBm (see Note 1 at the end of annex B) |
| 06 | 1 byte (fixed) | Type for Downlink channel number encoding | Used for license-exempt operation only |
| 01 | 1 byte | Length for Downlink channel number encoding | |
| 09 | 1 byte (fixed) | Value for Downlink channel number encoding | The Channel Number (Channel Nr), an 8-bit value, allows the calculation of the channel centre frequency for license-exempt frequency bands |
| 07 | 1 byte (fixed) | Type for TTG (Transmit/receive Transition Gap) encoding | Expressed in Physical Slot |
| 01 | 1 byte | Length for TTG (Transmit/receive Transition Gap) encoding | |
| 2D | 1 byte | Value for TTG (Transmit/receive Transition Gap) encoding | 148 Physical Slots |
| 08 | 1 byte (fixed) | Type for RTG (Receive/transmit Transition Gap) encoding | Expressed in Physical Slot |
| 01 | 1 byte | Length for RTG (Receive/transmit Transition Gap) encoding | |
| 2D | 1 byte | Value for RTG (Receive/transmit Transition Gap) encoding | 84 Physical Slots |
| 09 | 1 byte (fixed) | Type for Initial Ranging Maximal Received Signal Strength at BS encoding | RSSIR, max: Initial Ranging Maximal Received Signal Strength at BS |
| 02 | 1 byte | Length for Initial Ranging Maximal Received Signal Strength at BS encoding | |
| FFE4 | 2 bytes | Value for Initial Ranging Maximal Received Signal Strength at BS encoding | Signed in units of 1 dBm (see Note 1 below). FFE4= -−28dBm (10−5.8 W) |
| A (decimal: 10) | 1 byte (fixed) | Type for Channel Switch Frame Number encoding | Used for license-exempt operation only. In the case of DFS (Dynamic Frequency Selection), the new channel to be used is deduced by using this Channel Switch Frame Number |
| 03 | 1 byte | Length for Channel Switch Frame Number encoding | See Rule for TLV length |
| 000003 | 3 bytes | Value for Channel Switch Frame Number encoding | +3 |
| C (decimal: 12) | 1 byte (fixed) | Type for Downlink centre frequency encoding | The centre of the frequency band in which a base station (BS) or SS is intended to transmit in kHz |
| 04 | 1 byte | Length for Downlink centre frequency encoding | |
| 0036 5240 | 4 bytes | Value for Downlink centre frequency encoding | 00365240 (0000,0000,0011,0110,0101,1111,1110,1010)=3560000 kHz (3.56 GHz) |
| D (decimal: 13) | 1 byte (fixed) | Type for Base Station ID encoding | The Base Station ID is a 48-bit long field identifying the BS (not the MAC address) |
| 06 | 1 byte | Length for Base Station ID encoding | |
| AE54AA 123456 | 6 bytes | Value for Base Station ID encoding | The Base Station ID is programmable. The MS 24 bits must be used as the operator ID. A random value has been chosen here |
| E (decimal: 14) | 1 byte (fixed) | Type for Frame Duration Code encoding | The Frame Duration Code values are given in the standard |
| 01 | 1 byte | Length for Frame Duration Code encoding | |
| 03 | 1 bytes | Value for Frame Duration Code encoding | The code corresponding to 8 ms (see Table 232 of 802.16-2004) |
| F (decimal: 15) | 1 byte (fixed) | Type for Frame Number encoding | The Frame Number is a modulo 212 number (a 12-bit-number) which is increased by one for every frame |
| 03 | 1 byte | Length for Frame Number encoding | |
| A0B1EE | 3 bytes | Value for Frame Number encoding | The frame number of the frame containing the DCD message |
| 94th (decimal: 148) | 1 byte (fixed) | Type for MAC version encoding | Specifies the version of IEEE 802.16 to which the message originator conforms |
| 01 | 1 byte | Length for MAC version encoding | |
| 04 | 1 byte | Value for MAC version encoding | Indicates conformance with IEEE Std 802.16-2004 |
Open table as spreadsheet Start of Burst Profile Encoding values for DIUC value = 0101 (hexadecimal: 5). This part is TLV encoded.
| 01 | 1 byte (fixed) | Type for Frequency encoding | Downlink frequency of this burst profile in kHz |
| 04 | 1 byte | Length for Frequency encoding | |
| 0036 5FEA | 4 bytes | Value for Frequency encoding | 00365FEA (0000,0000,0011,0110,0101,1111,1110,1010)=3563 500 kHz (3.5635 GHz) |
| 96 (decimal: 150) | 1 byte (fixed) | Type for FEC Code encoding | Provides the modulation and the coding scheme of the burst profile |
| 01 | 1 byte | Length for FEC Code encoding | |
| 03 | 1 byte | Value for FEC code encoding | This value corresponds to 16-QAM modulation and Reed-Solomon CC, coding rate = 1/2 |
| 97 (decimal: 151) | 1 byte (fixed) | Type for DIUC mandatory exit threshold encoding | CINR (Carrier-to-Interference-and-Noise Ratio) used for burst profile (or equivalently DIUC) selection. In 0.25 dB units. |
| 01 | 1 byte | Length for DIUC mandatory exit threshold encoding | |
| 30 (decimal: 48) | 1 byte | Value for DIUC mandatory exit threshold encoding | Corresponds to 48 × 0.25 dB = 12 dB |
| 98 (decimal: 152) | 1 byte (fixed) | Type for DIUC mandatory entry threshold encoding | CINR (Carrier-to-Interference-and-Noise Ratio) used for burst profile (or equivalently DIUC) selection. In 0.25 dB units. |
| 01 | 1 byte | Length for DIUC mandatory entry threshold encoding | |
| 36 (decimal: 54) | 1 byte | Value for DIUC mandatory entry threshold encoding | Corresponds to 54 × 0.25 dB = 13.5 dB |
| 99 (decimal: 153) | 1 byte (fixed) | Type for TCS_enable encoding | The TCS (Transmission Convergence Sublayer) is an optional mechanism for the OFDM PHY (8.1.4.3) |
| 0 = TCS disabled | |||
| 1 = TCS enabled 2−255 = Reserved | |||
| 01 | 1 byte | Length for TCS_enable encoding | |
| 1 | 1 byte | Value for TCS_enable encoding | 1 = TCS enabled |
Open table as spreadsheet Start of Downlink Burst Profile Description for DIUC value = 1010 (hexadecimal: A). This part is TLV encoded.
| 01 | 8b (fixed) | Downlink_Burst_Profile Type | Downlink_Burst_Profile Indicator |
| 44 (decimal: 67) | 8b (fixed) | Downlink_Burst_Profile Length | 67 bytes for the overal Downlink_Burst_Profile of DIUC = 1010 |
| 0 | 4b (fixed) | Reserved | Set to zero |
| A | 4b (fixed) | DIUC value | This value of DIUC will be associated with the Downlink Burst Profile and Thresholds defined in the following |
Open table as spreadsheet Start of Channel Encodings values for DIUC value = 1010 (hexadecimal: A). This part is TLV encoded.
| 01 | 1 byte (fixed) | Type for Downlink_Burst_Profile encoding | The number of bytes in the overall object, including embedded TLV items |
| 01 | 1 byte | Length for Downlink_Burst_Profile encoding | See Rule for TLV Length |
| 44 (decimal: 67) | 1 byte | Value for Downlink_Burst_Profile encoding | 67 bytes for the overall Downlink_Burst_Profile of DIUC = 1010 |
| 02 | 1 byte (fixed) | Type for BS EIRP encoding | The BS Transmitted Power (effective isotropic radiated power) |
| 01 | 1 byte | Length for BS EIRP encoding | See Rule for TLV Length |
| 1E | 1 byte | Value for BS EIRP encoding | Signed in units of 1 dBm (see Note 1 below). 1E = 30 dBm (1 W) |
| 06 | 1 byte (fixed) | Type for Downlink channel number encoding | Used for license-exempt operation only |
| 01 | 1 byte | Length for Downlink channel number encoding | |
| 09 | 1 byte (fixed) | Value for Downlink channel number encoding | The Channel Number (Channel Nr), an 8-bit value, allows the calculation of the channel centre frequency for license-exempt frequency bands |
| 07 | 1 byte (fixed) | Type for TTG (Transmit/receive Transition Gap) encoding | Expressed in Physical Slot |
| 01 | 1 byte | Length for TTG (Transmit/receive Transition Gap) encoding | |
| 3C | 1 byte | Value for TTG (Transmit/receive Transition Gap) encoding | 148 Physical Slots |
| 08 | 1 byte (fixed) | Type for RTG (Receive/transmit Transition Gap) encoding | Expressed in Physical Slot |
| 01 | 1 byte | Length for RTG (Receive/transmit Transition Gap) encoding | |
| 3C | 1 byte | Value for RTG (Receive/transmit Transition Gap) encoding | 84 Physical Slots |
| 09 | 1 byte (fixed) | Type for Initial Ranging Maximal Received Signal Strength at BS encoding | RSSIR, max: Initial Ranging Maximal Received Signal Strength at the BS |
| 02 | 1 byte | Length for Initial Ranging Maximal Received Signal Strength at BS encoding |
|
| FFE6 | 2 bytes | Value for Initial Ranging Maximal Received Signal Strength at BS encoding | Signed in units of 1 dBm (see Note 1 below). FFe6 = −26 dBm (10−5.6 W) |
| A (decimal: 10) | 1 byte (fixed) | Type for Channel Switch Frame Number encoding | Used for license-exempt operation only. In the case of DFS (Dynamic Frequency Selection), the new channel to be used is deduced by using this Channel Switch Frame Number |
| 03 | 1 byte | Length for Channel Switch Frame Number encoding | See Rule for TLV Length |
| 000003 | 3 bytes | Value for Channel Switch Frame Number encoding | +3 |
| C (decimal: 12) | 1 byte (fixed) | Type for Downlink centre frequency encoding | The centre of the frequency band in which a base station (BS) or SS is intended to transmit in kHz |
| 04 | 1 byte | Length for Downlink centre frequency encoding | |
| 0036 5240 | 4 bytes | Value for Downlink centre frequency encoding | 00365240 (0000,0000,0011,0110,0101,1111,1110,1010) = 3 560 000 kHz (3.56 GHz) |
| D (decimal: 13) | 1 byte (fixed) | Type for Base Station ID encoding | The Base Station ID is a 48-bit long field identifying the BS (not the MAC address) |
| 06 | 1 byte | Length for Base Station ID encoding | |
| AE54 123456 | 6 bytes | Value for Base Station ID encoding | The Base Station ID is programmable. The MS 24 bits must be used as the operator ID. A random value has been chosen here |
| E (decimal: 14) | 1 byte (fixed) | Type for Frame Duration Code encoding | The Frame Duration Code values are given in the standard |
| 01 | 1 byte | Length for Frame Duration Code encoding | |
| 04 | 1 byte | Value for Frame Duration Code encoding | The code corresponding to 10 ms (see Table 232 of 802.16-2004) |
| F (decimal: 15) | 1 byte (fixed) | Type for Frame Number encoding | The Frame Number is a modulo 212 number (a 12-bit-number) which is increased by one for every frame |
| 03 | 1 byte | Length for Frame Number encoding | |
| A0b1EE | 3 bytes | Value for Frame Number encoding | The Frame Number of the frame containing the DCD message |
| 94 (decimal: 148) | 1 byte (fixed) | Type for MAC, version encoding | Specifies the version of IEEE 802.16 to which the message originator conforms |
| 01 | 1 byte | Length for MAC version encoding | |
| 04 | 1 byte | Value for MAC version encoding | Indicates conformance with IEEE Std 802.16-2004 |
Open table as spreadsheet Start of Burst Profile Encoding values for DIUC value = 1010 (hexadecimal: A). This part is TLV encoded.
| 01 | 1 byte (fixed) | Type for Frequency encoding | Downlink frequency of this burst profile in kHz |
| 04 | 1 byte | Length for Frequency encoding | |
| 0036 5FEA | 4 bytes | Value for Frequency encoding | 00365FEA (0000,0000,0011,0110,0101,1111,1110,1010) = 3 563 500 kHz (3.5635 GHz) |
| 96 (decimal: 150) | 1 byte (fixed) | Type for FEC Code encoding | Provides the modulation and the coding scheme of the burst profile |
| 01 | 1 byte | Length for FEC Code encoding | |
| 05 | 1 byte | Value for FEC Code encoding | This value corresponds to 64-QAM modulation and Reed-Solomon CC, coding rate = 2/3 |
| 97 (decimal: 151) | 1 byte (fixed) | Type for DIUC mandatory exit threshold encoding | CINR (Carrier-to-Interference-and-Noise Ratio) used for burst profile (or equivalently DIUC) selection. In 0.25 dB units |
| 01 | 1 byte | Length for DIUC mandatory exit threshold encoding | |
| 52 (decimal: 82) | 1 byte | Value for DIUC mandatory exit threshold encoding | Corresponds to 82 × 0.25 dB = 20.5 dB |
| 98 (decimal: 152) | 1 byte (fixed) | Type for DIUC mandatory entry threshold encoding | CINR (Carrier-to-Interference-and-Noise Ratio) used for brust profile (or equivalently DIUC) selection. In 0.25 dB units |
| 01 | 1 byte | Length for DIUC mandatory entry threshold encoding | |
| 62 (decimal: 98) | 1 byte | Value for DIUC mandatory entry threshold encoding | Corresponds to 98 × 0.25 dB = 24.5 dB |
| 99 (decimal: 153) | 1 byte (fixed) | Type for TCS_enable encoding | The TCS (Transmission Sublayer) is an optional mechanism for the OFDM PHY |
| 01 | 1 byte | Length for TCS_enable encoding | |
| 1 | 1 byte | Value for TCS_enable encoding | 1 = TCS enabled |
| Note 1. No specific rule is given in the standard (802.16-2004) for some parameters coding. It is presumed that for N possible combinations (e.g. for 16 bits, 65 536 combinations), the first N/2 combinations (0 to 32767) represent positive numbers while the next 32768 combinations (32768 to 65536) represent negative numbers (two's complement). In order to get ‘-28’, 28 is substracted from the number of combinations (65536) in order to get 65508 (binary: 1111,1111,1110,0100, hexadecimal: FFE4). | |||
Open table as spreadsheet 
EAN: 2147483647
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