Synchronisation using pilots and data

1. A method for synchronization of a receiver by estimating a time offset in a received signal by a receiver using pilot symbols and data symbols, the method comprising:

receiving a signal comprising pilot symbols and data symbols;

sampling the received signal; and

processing an optimizing function of the sampled received signal at a finite number of possible time offsets to produce an estimate of the time offset, wherein the optimization function is a function of both pilot symbols and data symbols,

wherein the optimizing function is processed at the finite number of possible time offsets τ 1 , τ 2 , . . . , τ K for some positive integer K where τ i+1 −τ i =Δ, and Δ=T/c where T is the symbol period of the pilot symbols and data symbols, and c is a positive integer.

2. The method of claim 1 , wherein the optimizing function comprises a function of the sampled received signal with a finite number of possible pilots.

3. The method of claim 1 , wherein the optimizing function comprises a function of the sampled received signal with a finite number of possible data symbols.

4. The method of claim 1 , wherein the optimizing function comprises a mathematical function, or equivalent, of SS(τ)=Z(τ)+Y(τ) where Z is a function of the sampled received signal, the time offset and positions of a finite number of the data symbols, and Y is a function of the sampled received signal, the time offset and positions and values of a finite number of possible pilot symbols.

5. The method of claim 1 , wherein the data symbols are complex numbers.

6. The method of claim 1 , wherein the data symbols are from a finite set on a complex unit circle.

7. The method of claim 6 , wherein the data symbols are from a M-PSK constellations.

8. A method for synchronization of a receiver by estimating a time offset in a received signal by a receiver using pilot symbols and data symbols, the method comprising:

receiving a signal comprising pilot symbols and data symbols;

sampling the received signal; and

processing an optimizing function of the sampled received signal at a finite number of possible time offsets to produce an estimate of the time offset, wherein the optimization function is a function of both pilot symbols and data symbols,

wherein the step of processing an optimizing function comprises:

computing b k for all k=1+c min (P∪D), . . . , K+c max (P∪D), where P is set of indices describing positions of the pilot symbols, D is set of indices describing positions of the data symbols, K and c are positive integers;

computing Z k =Z(τ k ), based on b k , for all k=1, . . . , K, where τ k is a possible time offset;

computing Y k =Y(τ k ), based on b k , for all k=1, . . . , K, Y(τ k ) being a different function from Z(τ k );

computing kε{1, . . . , K} that maximises Z k +Y k ;

computing an approximate time offset estimate, {tilde over (τ)}, based on k that maximises Z k +Y k ;

applying a numerical optimization procedure initialized with {tilde over (τ)} to produce the estimate of the time offset.

9. The method of claim 8 , wherein the step of computing an approximate time offset estimate comprises:

computing {tilde over (τ)}=τ 1 +Δ({circumflex over (k)}−1)=τ min +Δ({circumflex over (k)}−1), where k is the k that maximises Z k +Y k , Δ=T/c where T is the symbol period of the pilot symbols and data symbols, and c is a positive integer.

10. A non-transitory processor readable medium, comprising instructions for synchronization of a receiver by causing a processor to carry out a method for estimating a time offset in a received signal by a receiver using pilot symbols and data symbols, comprising:

receiving a signal comprising pilot symbols and data symbols;

sampling the received signal; and

processing an optimizing function of the sampled received signal at a finite number of possible time offsets to produce an estimate of the time offset, wherein the optimization function is a function of both pilot symbols and data symbols,

wherein the optimizing function is processed at the finite number of possible time offsets τ 1 , τ 2 , . . . , τ K for some positive integer K where τ i+1 −τ i =Δ, and Δ=T/c where T is the symbol period of the pilot symbols and data symbols, and c is a positive integer.

11. A receiver comprising:

a receiving module for receiving a signal comprising pilot symbols and data symbols and sampling the received signal; and

a processing module comprising a memory and a processor operatively coupled to the memory and configured to carry out a method for synchronization of the receiver by estimating a time offset in the sampled received signal received by the receiving module using pilot symbols and data symbols, the method comprising:

processing an optimizing function of the sampled received signal at a finite number of possible time offsets to produce an estimate of the time offset, wherein the optimization function is a function of both pilot symbols and data symbols,

wherein the optimizing function is processed at the finite number of possible time offsets τ 1 , τ 2 , . . . , τ K for some positive integer K where τ i+1 −τ i =Δ, and Δ=T/c where T is the symbol period of the pilot symbols and data symbols, and c is a positive integer.

12. A non-transitory processor readable medium, comprising instructions for causing a processor to carry out a method for synchronisation of a receiver by estimating a time offset in a received signal by a receiver using pilot symbols and data symbols comprising:

receiving a signal comprising pilot symbols and data symbols;

sampling the received signal and

processing an optimizing function of the sampled received signal at a finite number of possible time offsets to produce an estimate of the time offset wherein the optimization function is a function of both pilot symbols and data symbols,

wherein the step of processing an optimizing function comprises:

computing b k for all k=1+c min (P∪D), . . . , K+c max (P∪D), where P is set of indices describing positions of the pilot symbols, D is set of indices describing positions of the data symbols, K and c are positive integers;

computing Z k =Z(τ k ), based on b k , for all k=1, . . . , K, where τ k is a possible time offset;

computing Y k =Y(τ k ), based on b k , for all k=1, . . . , K, Y(τ k ) being a different function from Z(τ k );

computing kε{1, . . . , K} that maximises Z k +Y k ;

computing an approximate time offset estimate, {tilde over (τ)}, based on k that maximises Z k +Y k ;

applying a numerical optimization procedure initialized with {tilde over (τ)} to produce the estimate of the time offset.

13. The non-transitory processor readable medium of claim 12 , wherein the step of computing an approximate time offset estimate comprises:

computing {tilde over (τ)}i=τ 1 +Δ({circumflex over (k)}−1)=τ min +Δ({circumflex over (k)}−1), where k is the k that maximises Z k +Y k , Δ=T/c where T is the symbol period of the pilot symbols and data symbols, and c is a positive integer.

14. A receiver comprising:

a receiving module for receiving a signal comprising pilot symbols and data symbols and sampling the received signal; and

a processing module comprising a memory and a processor operatively coupled to the memory and configured to carry out a method for synchronisation of the receiver by estimating a time offset in the sampled received signal received by the receiving module using pilot symbols and data symbols, the method comprising:

processing an optimizing function of the sampled received signal at a finite number of possible time offsets to produce an estimate of the time offset wherein the optimization function is a function of both pilot symbols and data symbols,

wherein the receiving module is further configured such that processing an optimizing function comprises:

computing b k for all k=1+c min (P∪D), . . . , K+c max (P∪D), where P is set of indices describing positions of the pilots symbols, D is set of indices describing positions of the data symbols, K and c are positive integers;

computing Z k =Z(τ k ), based on b k , for all k=1, . . . , K, where τ k is an possible time offset;

computing Y k =Y(τ k ), based on b k , for all k=1, . . . , K, Y(τ k ) being a different function from Z(τ k );

computing kε{1, . . . K} that maximises Z k +Y k ;

computing an approximate time offset estimate, {tilde over (τ)}, based on k that maximises Z k +Y k ;

applying a numerical optimization procedure initialized with {tilde over (τ)} to produce the estimate of the time offset.

15. The receiver of claim 14 , wherein the step of computing an approximate time offset estimate comprises:

computing {tilde over (τ)}=τ 1 +Δ({circumflex over (k)}−1)=τ min +Δ({circumflex over (k)}−1), where k is the k that maximises Z k +Y k , Δ=T/c where T is the symbol period of the pilot symbols and data symbols, and c is a positive integer.