US 7,068,746 B1 · Base station transceiver to radio network controller synchronization filtering function

Abstract

A method for synchronizing communications in a wireless communications network wherein time synchronization is performed between a clock master and a clock slave. To achieve synchronization between the clock master and the clock slave, several time synchronization passes are initiated by the clock slave to the clock master. For every pass, each clock slave component generates and transmits a first timing cell containing a transmission time based on the clock slave's component clock, to the clock master. Upon receipt of the first timing cell, the clock master generates and transmits to the clock slave component a second timing cell containing the time the clock master received the first timing cell and the time the clock master transmitted the second timing cell. Upon receipt of the second timing cell, the clock slave component will obtain its reception time and calculate a transmission delay based on the reception time and the timing information contained in the timing cells.

Claims31

Dependent claims

A method of performing time synchronization between a clock master having a first clock and a clock slave having a second dock, said method comprising the steps of:

(a) sending a first message to the clock master, the first message comprising information indicating a transmission time (“first transmission time”) of the first message;
(b) receiving a second message from the clock master, the second message comprising information indicating a reception time (“first reception time”) of the first message and a transmission time (“second transmission time”) of the second message;
(c) obtaining at the clock slave a reception time (“second reception time”) of the second message;
(d) calculating a transmission delay between the clock slave and clock master from the first and second reception times and the first and second transmission times;
(e) determining if the calculated transmission delay is within a time window;
and
(f) updating an accumulated delay with the calculated transmission delay if the calculated transmission delay is within the time window;
wherein said window has a first and a second threshold, said thresholds are adjustable such that the window is a sliding window, the first threshold represents a best delay, the second threshold represents a maximum allowable difference from the best delay, and the best delay is a minimum calculated transmission delay;
and wherein said step of determining if the calculated transmission delay is within the window comprises:
determining if the calculated transmission delay is less than the best delay;
and
if the calculated transmission delay is less than the best delay;
storing the calculated transmission delay as the undated best delay, discarding the calculated transmission delay, resetting the accumulated delay, and repeating steps (a)–(e) at least one further time.

10 more elements

A method of performing time synchronization between a clock master having a first clock and a clock slave having a second clock, said method comprising the steps of:

(a) sending a first message to the clock master, the first message comprising information indicating a transmission time (“first transmission time”) of the first message;
(b) receiving a second message from the clock master, the second message comprising information indicating a reception time (“first reception time”) of the first message and a transmission time (“second transmission time”) of the second message;
(c) obtaining at the clock slave a second reception time of the second message;
(d) calculating a transmission delay between the clock slave and clock master from the first and second reception times and the first and second transmission times;
(e) determining if the calculated transmission delay is within a time window of acceptable delays and updating an accumulated delay with the calculated transmission delay if the calculated transmission delay is within the time window;
(f) determining if said calculated transmission delay is less than a best delay, wherein the best delay represents a calculated transmission delay with a smallest delay in comparison to other calculated transmission delays;
and
(g) if the calculated transmission delay is less than the best delay;
storing the calculated transmission delay as the updated best delay;
discarding the calculated transmission delay, resetting the accumulated delay and repeating steps (a)–(f) at least one further time.

7 more elements

A base station for use in a wireless telecommunications system comprising:

a clock;
and
a controller for;
sending a first message to a clock master of said system comprising information indicating a first transmission time of the first message;
receiving a second message from the clock master comprising information indicating a first reception time of the first message and a second transmission time of the second message;
obtaining a second reception time of the second message;
calculating a transmission delay from the first and second reception times and the first and second transmission times;
determining if the calculated transmission delay is within a time window and updating an accumulated delay with the calculated transmission delay if the calculated transmission delay is within the time window;
determining if said calculated transmission delay is less than a best delay, wherein the best delay represents a calculated transmission delay with a smallest delay in comparison to other calculated transmission delays;
and
if the calculated transmission delay is less than the best delay, storing the calculated transmission delay as the updated best delay, discarding the calculated transmission delay, resetting the accumulated delay and re-sending the first message at least one further time.

8 more elements

Dependencies are inferred from the claim text.

Base station transceiver to radio network controller synchronization filtering function

Life of this patent

Base station transceiver to radio network controller synchronization filtering function

Life of this patent

Abstract

Claims31