Data Subcarrier Modulation Format (802.16 OFDM)

Data Subcarrier Modulation specify the Data Subcarrier Modulation Format. The modulation format is shown in the SubFrame Info error summary trace data. This parameter does not affect the demodulation of the pilot subcarriers, which are always BPSK modulation.

OFDM IEEE 802.16a/d FCH Symbol - RATE_ID Field

The 802.16 OFDM downlink subframe contains Preamble symbols followed by the FCH symbol and Data symbols. The FCH symbol is always transmitted using BPSK modulation. The FCH symbol contains information about the first four data bursts in the downlink subframe. However, the data modulation formats of the 2nd through 4th burst are described by referring to a DIUC, which is not available to the VSA. Because of this, the VSA uses FCH only for the first data burst in the subframe.

 image\WiMaxRateID_wmf.jpg

The FCH symbol's Rate_ID and Length fields describe the first data burst. The Rate_ID field transmits the modulation and coding to be used in the first downlink burst immediately following the FCH. The Rate_ID encoding is shown in the following table. The Rate_ID encoding is static and cannot be changed during system operation. The Length field contains the number of OFDM symbols in the burst. This information is shown in the Subframe Info when a FCH is present.

OFDM Rate ID encodings

 

Rate_ID

Modulation
RS-CC rate 

0

BPSK 1/2

1

QPSK 1/2

2

QPSK 3/4

3

16-QAM 1/2

4

16-QAM 3/4

5

64-QAM 2/3

6

64-QAM 3/4

7-15

reserved

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See Also

Format Tab (IEEE 802.16 OFDM Demod Properties)

IEEE 802.16 OFDM Demod Properties Dialog Box

802.16 OFDM Overview

       

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