Symbol timing estimation in communication systems

Symbol timing estimation apparatus for use in a communication system in which symbols are successively transmitted in a signal, each symbol comprising a predetermined number of symbol samples, and in which a series of L symbol samples is repeated N symbol samples after its original appearance, where L and N are integers, said apparatus comprising:

• a correlation unit which receives said signal and processes the symbol samples in the received signal using N and L to obtain a correlation function for the originally-appearing series and the repeated series;
• a basic measure producing unit which produces a basic measure for symbol timing estimation based on the obtained correlation function;
• a second-derivative measure producing unit which produces a second-derivative measure for symbol timing estimation based on a second derivative of said basic measure;
• and
• a symbol timing estimating unit which estimates the symbol timing based on said basic and second-derivative measures.

A receiver, for use in a communication system in which symbols are successively transmitted in a signal, each symbol comprising a predetermined number of symbol samples, and in which a series of L symbol samples is repeated N symbol samples after its original appearance, where L and N are integers, said receiver comprising:

• a correlation unit which receives said signal and processes the symbol samples in the received signal using N and L to obtain a correlation function for the originally-appearing series and the repeated series;
• a basic measure producing unit which produces a basic measure for symbol timing estimation based on the obtained correlation function;
• a second-derivative measure producing unit which produces a second-derivative measure for symbol timing estimation based on a second derivative of said basic measure;
• and
• a symbol timing estimating unit which estimates the symbol timing based on said basic and second-derivative measures.

A user equipment, for use in a cellular communications system in which symbols are successively transmitted in a signal, each symbol comprising a predetermined number of symbol samples, and in which a series of L symbol samples is repeated N symbol samples after its original appearance, where L and N are integers, said user equipment comprising:

• a correlation unit which receives said signal and processes the symbol samples in the received signal using N and L to obtain a correlation function for the originally-appearing series and the repeated series;
• a basic measure producing unit which produces a basic measure for symbol timing estimation based on the obtained correlation function;
• a second-derivative measure producing unit which produces a second-derivative measure for symbol timing estimation based on a second derivative of said basic measure;
• and
• a symbol timing estimating unit which estimates the symbol timing based on said basic and second-derivative measures.

A recording medium storing an operating program which, when run on a processor in a receiver of a communication system in which symbols are successively transmitted in a signal, each symbol comprising a predetermined number of symbol samples, and in which a series of L symbol samples is repeated N symbol samples after its original appearance, where L and N are integers, causes the processor to:

• receive said signal and process the symbol samples in the received signal using N and L to obtain a correlation function for the originally-appearing series and the repeated series;
• produce a basic measure for symbol timing estimation based on the obtained correlation function;
• produce a second-derivative measure for symbol timing estimation based on a second derivative of the basic measure;
• and
• estimate the symbol timing based on the basic and second-derivative measures.

Symbol timing estimation apparatus for use in a communication system in which symbols are successively transmitted in a signal, each symbol comprising a predetermined number of symbol samples, and in which a series of L symbol samples is repeated N symbol samples after its original appearance, where L and N are integers, said apparatus comprising:

• correlation means operable to receive said signal and to process the symbol samples in the received signal using N and L to obtain a correlation function for the originally-appearing series and the repeated series;
• basic measure producing means operable to produce a basic measure for symbol timing estimation based on the obtained correlation function;
• second-derivative measure producing means for producing a second-derivative measure for symbol timing estimation based on a second derivative of said basic measure;
• and
• symbol timing estimating means for estimating the symbol timing based on said basic and second-derivative measures.