Preamble and pilots (802.16 OFDMA)
: Cleared (See OFDMA Standard Presets Table.)
(applies to only)
The equalizer is trained by analyzing the entire OFDMA burst, including the Channel Estimation Sequence (contained in the preamble) and the Pilot symbols. This type of training generally gives a more accurate estimate of the true response of the transmission channel.
When demodulating the IEEE Institute of Electrical and Electronics Engineers. A US-based membership organisation that includes engineers, scientists, and students in electronics and related fields. The IEEE developed the 802 series wired and wireless LAN standards. Visit the IEEE at http://www.ieee.org 802.16 OFDMA signal, the VSA uses an equalizer to correct for linear impairments in the signal path, such as, multi-path. Switching between the different equalizer training methods can help isolate problems contributing to increased EVM Error vector magnitude (EVM): A quality metric in digital communication systems. See the EVM metric in the Error Summary Table topic in each demodulator for more information on how EVM is calculated for that modulation format./RCE Relative Constellation Error is the RMS level of the Error Vector Magnitude, averaged over all subcarriers and all detected OFDM symbols..
The advantages of using the method of equalization include the following:
- The equalizer coefficients typically reflect the linear channel impairment with greater accuracy, as the data set used to train the equalizer is larger and is less affected by turn-on transient effects in the burst.
- The EVM/RCE is typically lower because the equalizer is less impacted by noise and other forms of distortion. EVM/RCE represents the error due to noise, non-linear distortion, spurious and residual linear distortion.)
- This method complies with the description in the "RMS constellation error measurement for SS " section "8.4.12.3.2" of the IEEE Std IEEE 802.16e-2005 standard.
The disadvantages of using the method of equalization include the following:
- This equalizer training method is less likely to accurately reflect the performance of a typical OFDMA receiver. This type of equalizer computation is less likely to be used in practical receivers because it is more complicated and therefore more expensive to implement.
See Also
