Fast resynchronization for reception in time slicing
View Patent ↗A method and an apparatus for achieving fast resynchronization of received signals in a time slice in DVB-T/H systems. When the clock drift is low, the location of the symbol window can be decided based on a previous time slice. When the clock drift is high and when there are large delay spreads, the location of the symbol window can be decided based on the detected scattered pilot positions. The placement of the symbol window can further be enhanced through processing of the received TPS bits.
1. A method of fast resynchronization comprising:
receiving into a receiver a plurality of multi-carrier frames transmitted in time slices, each of the plurality of multi-carrier frames including a plurality of OFDM symbols;
obtaining first TPS bits from a first plurality of frames;
placing an initial window to a fifth frame for a coarse fractional frequency offset estimation and an integer frequency offset estimation;
extracting second TPS bits from the fifth frame;
correlating the extracted second TPS bits with the obtained first TPS bits; and
calculating a symbol number based on the correlation of the TPS bits.
2. The method of claim 1 , wherein the correlation comprises:
computing an expected frame number and an expected symbol number based on the time that expires since a last time slice.
3. The method of claim 2 , wherein the computing of the expected frame number is based on the following formula:
Frame number of first symbol in time slice (n+1)=floor({68×Frame number of last symbol in time slice n+Symbol number of last symbol in time slice n+CEIL([Time stamp of first symbol in time slice (n+1)−Timestamp of last symbol in time slice n]/OFDM symbol time) }/ 68) modulo 4.
4. The method of claim 2 , wherein the computing of the expected symbol number is based on the following formula:
Symbol number of first symbol in time slice (n+1)={Symbol number of last symbol in time slice n+CEIL([Time stamp of first symbol in time slice (n+1)−Timestamp of last symbol in time slice n]/OFDM symbol time)} modulo 68.
5. The method of claim 1 , wherein the obtaining first TPS bits comprises using a full frame synchronization and the first plurality of frames comprises four consecutive frames.