The methods discussed below are not intended to be an exhaustive listing, but to form a foundation
and spark innovative designs.
6.5.1 Pilot Error Rate
This first quality estimation technique is based on the assumption that certain bit fields (e.g., pilot
bits) will be known to the receiver; similar assumptions were made earlier on the topic of training the
equalizer. In this case, we will use this a priori knowledge to calculate the Pilot Error Rate (PER) of
the communication link. We will provide a time slot structure for sake of discussion (see Fig. 6.35).
Some of the disadvantages of this technique is that it requires time slot synchronization. This may
not be an issue for channels actively being used in the communication link but may be an issue if the
receiver is instructed to change frequency bands to measure its quality indication in a relatively short
period of time. Also depending on the operating point of the communication system, available information,
channel conditions, and so on, many slots may be required to provide statistical confidence
in the measured quantity.
Here a simplified receiver block diagram that calculates the pilot errors over the current time slot
and then averages this value using the previously measured values is shown in Fig.
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