Transmitting data or determining a frequency and timing estimate of a received signal

A method of determining a frequency and timing estimate of a received signal, the method comprising:

• obtaining samples of a preamble in a received signal;
• performing autocorrelation of at least a first portion of the samples to determine a first frequency estimate of the received signal;
• performing frequency correction on the samples based on the first frequency estimate to obtain first frequency corrected samples;
• and
• performing cross-correlation of at least a second portion of the first frequency corrected samples with a predetermined cross-correlation sequence to determine a timing estimate of the received signal, wherein the predetermined cross-correlation sequence includes a Barker bit sequence.

An apparatus for transmitting data, wherein the data includes a preamble, the apparatus comprising:

• a processor;
• and
• a memory, the memory containing instructions executable by the processor such that the apparatus is operable to:
• transmit the data including the preamble, wherein the preamble includes a first portion comprising a predetermined bit sequence repeated a predetermined number of times, and a second portion comprising a Barker bit sequence;
• wherein one or more of the following apply:
• the first portion and the second portion share one or more bits, the first portion of the preamble comprises a repeating predetermined symbol bit sequence, the preamble comprises 52 bits, the Barker bit sequence has 13 bits, and the predetermined bit sequence comprises an even number of bits;
• and
• wherein one or more of the following apply:
• the number of bits in the predetermined symbol bit sequence is 4, and a number of bits in the predetermined bit sequence with a value ‘1’ is equal to a number of bits in the first portion with a value ‘0’.