Patent ID: 6687233
Filing Date: 2004-02-03
Classification: H04L

Abstract:
A method of rate detection at a receiving end of a digital communications system of a type wherein convolutional encoded digital data transmitted over a medium has an information data rate variably selected at a transmitting end from a rate set containing a full rate and one or more possible lower rates which equals the full rate divided by respective different integers associated with the possible lower rates, the data being repeated for the lower rates to achieve the same apparent transmission rate as the full rate, said method comprising:de-repeating received convolutional encoded data in accordance with each of the possible lower rates; decoding the received convolutional encoded data and each of the de-repeated convolutional encoded data which has been de-repeated in accordance with each of the possible lower rates; convolutional re-encoding the decoded received convolutional encoded data and each of the de-repeated convolutional encoded data which has been de-repeated in accordance with each of the possible lower rates; forming a full rate correlation between the received convolution encoded data and the convolution re-encoded decoded received convolution encoded data, and lower rate correlations between the de-repeated received convolution encoded data and the convolution re-encoded decoded de-repeated received convolution encoded data for each possible lower rate, the lower rate correlations being scaled by the integers associated with the lower rates; and first determining whether or not the transmitted data rate is the full rate by checking if one or more first conditions are satisfied, one of the first conditions being whether the full rate correlation plus a predetermined first threshold is greater than, or greater than or equal to, a maximum of the lower rate correlations.