Method and an apparatus for synchronising a receiver timing to transmitter timing

An apparatus for synchronising a receiver timing to a transmitter timing using a known preamble of a signal, said preamble comprising at least one training sequence, said apparatus comprising:

• a cross-correlator, configured to estimate an absolute value of a cross-correlation metric based on input samples of said signal and samples of said training sequence of said preamble;
• a signal power estimator, configured to estimate a signal power using a short-term average of said estimated absolute value of said cross-correlation metric;
• a noise floor power estimator, configured to estimate a noise floor power using a delayed long-term average of said estimated absolute value of said cross-correlation metric;
• device to estimate a power normalized cross-correlation metric (PNCC metric), as a function of said estimated signal power and said estimated noise floor power;
• decision device, configured to decide that at least one time synchronisation event occurs when at least one first synchronisation criterion is satisfied corresponding to said PNCC metric exceeding a threshold value and further configured to store, for each time a synchronisation event occurs, a magnitude value of said PNCC metric and a corresponding time index;
• and
• analysing device, configured to analyse said at least one stored time index and corresponding magnitude values of said PNCC metric to synchronise timing in said receiver to timing in said transmitter, using a timing synchronisation index that is based on at least said at least one stored time index;
• wherein the apparatus is further configured to update said threshold value with a PNCC threshold value corresponding to the magnitude value of said PNCC metric for each time said decision device decides that a synchronisation event occurs.