Apparatus and method of synchronization using delay measurements

A method of measuring delay between a first interface pair and a second interface pair in a communications system, wherein the first interface pair includes a first interface and a second interface and the second interface pair includes a third interface and a fourth interface, and wherein the distance between the first interface pair and the second interface pair is more than negligible, comprising:

• transmitting a first signal from the first interface and simultaneously providing a first clock to reset a counting clock, said first clock having a period equal to or longer than the delay between the first interface and the third interface;
• receiving a delayed first signal at the third interface;
• transmitting said delayed first signal from the fourth interface, wherein the distance between the third interface and the fourth interface is negligible;
• receiving a further delayed first signal at the second interface, and simultaneously stopping said counting clock;
• calculating the number of counts elapsed in said counting clock between said resetting and said stopping of said counting clock, wherein each count of said counting clock equals the period of said counting clock;
• and
• multiplying said number of counts with the period of said counting clock.

A method of synchronizing a handset to a base station in a wireless communications system, comprising:

• transmitting a first signal from the base station and simultaneously resetting a counting clock in the base station by providing a first clock, said first clock having a period equal to or longer than a delay between the base station and the handset;
• receiving a delayed first signal and recent delay value at the handset;
• transmitting said delayed first signal from the handset at a time determined by a linear function of the delay value;
• receiving a further delayed first signal at the base station and simultaneously stopping said counting clock;
• calculating the number of counts elapsed in said counting clock between said resetting and said stopping of said counting clock, wherein each count of said counting clock equals the period of said counting clock;
• and
• multiplying said number of counts with the period of said counting clock.

A method of synchronization in a wireless communications system, comprising:

• transmitting a first signal from a base station to a handset and simultaneously resetting a counting clock in said base station, wherein simultaneously resetting said counting clock comprises providing a first clock to reset said counting clock, said first clock having a period equal to or longer than the delay between the base station and the handset;
• receiving a delayed first signal and recent delay value at said handset;
• transmitting said delayed first signal from said handset at a time determined by a linear function of the delay value;
• receiving a further delayed first signal at said base station and simultaneously stopping said counting clock;
• calculating a first number of counts elapsed in said counting clock between said resetting and said stopping of said counting clock, wherein each count of said counting clock equals the period of said counting clock;
• repeating a predetermined number of times of said transmitting a first signal through said calculating to obtain a second nember of counts;
• adding said first and second number of counts for each of said predetermined number of repetitions to obtain a sum;
• multiplying said sum with the period of said counting clock;
• and
• dividing the product of said multiplying by the predetermined number of repetitions.

A method of synchronizing a first station with a second station in a communications system, wherein the distance between the first station and the second station is more than negligible, comprising:

• providing a first interface in the first station, said first interface transmitting a first signal and simultaneously providing a first clock signal to reset a counting clock in the first station, said first clock signal having a period equal to or longer than the delay between the first station and the second station;
• providing a second interface in the first station;
• providing a third interface in the second station, said third interface receiving a delayed first signal and recent delay value and transmitting said delayed first signal at a time determined by a linear function of the delay value;
• providing a fourth interface coupled to said third interface in the second station, said fourth interface receiving said delayed first signal and transmitting said delayed first signal, wherein the distance between said third interface and said fourth interface is negligible;
• receiving a further delayed first signal at said second interface, and simultaneously stopping said counting clock;
• providing a counter to determine the number of counts elapsed in said counting clock between said resetting and said stopping of said counting clock, wherein each count of said counter equals the period of said counting clock;
• and
• multiplying said number of counts with the period of said counting clock.

A communications system, comprising:

• a first station transmitting a first signal and resetting a counting clock in said first station;
• a second station receiving a delayed first signal from said first station and transmitting said delayed first signal to said first station, said first station simultaneously stopping said counting clock upon receiving a further delayed first signal from said second station, wherein the distance between said first station and said second station is more than negligible, and wherein resetting said counting clock comprises providing a first clock to reset said counting clock, said first clock having a period equal to or greater than the delay between the first station and the second station;
• a counter coupled to said first station to determine the number of counts elapsed in said counting clock between said resetting and said stopping of said counting clock, wherein each count of said counter equals the period of said counting clock;
• and
• arithmetic means coupled to said counter for multiplying said number of counts with the period of said counting clock.

An apparatus for delay measurements, comprising:

• a first interface pair including a first interface and a second interface, said first interface transmitting a first signal and simultaneously resetting a counting clock;
• a second interface pair including a third interface and a fourth interface, said third interface receiving a delayed first signal from said first interface, and said fourth interface transmitting said delayed first signal to said second interface, wherein the distance between said third interface and said fourth interface is negligible, said second interface receiving a further delayed first signal and simultaneously stopping said counting clock, and wherein simultaneously resetting said counting clock comprises providing a first clock to reset said counting clock, said first clock having a period equal to or greater than the delay between said first interface and said third interface;
• a counter coupled to said first interface pair to calculate the number of counts elapsed in said counting clock between said resetting and said stopping of said counting clock, wherein each count of said counting clock equals the period of said counting clock;
• and
• arithmetic means for multiplying said number of counts with the period of said counting clock.