Method and apparatus for synchronizing timing among radio ports in wireless communications systems using hierarchical scheme

Claim 3

A method in accordance with claim 1 wherein in step (l) each base unit independently waits a random time before repeating steps (d) through (j).

Claim 4

A method in accordance with claim 1 wherein a signal generated by a central controller initiates the start of steps (d) through (j) at each base unit.

Claim 5

A method in accordance with claim 1 wherein in step (g) each of the time differences is adjusted by a propagation delay from the transmitting base unit to the first base unit.

Claim 6

A method in accordance with claim 4 wherein the propagation delay is an estimated delay calculated from the average distance between fixed base units.

Claim 7

A method in accordance with claim 4 wherein the propagation delay that adjusts the time differences in step (g) is calculated separately for each transmitting base unit and is based for each on the distance between each transmitting base unit and the first base unit.

Claim 8

A method in accordance with claim 6 further comprising the steps of identifying the transmitting base units and retrieving the coordinates of the identified transmitting base units from a data base to calculate the distances between the transmitting base units and the first base unit.

Claim 9

A method in accordance with claim 1 wherein in step (g) only if the quality measure of a downlink signal received from a fixed base unit is above a predetermined threshold is the timing of that downlink signal used to calculate the average of time differences.

Claim 12

A method in accordance with claim 9 wherein in step (l) each port independently waits a random time before repeating steps (d) through (j).

Claim 13

A method in accordance with claim 9 wherein a signal generated by a central controller initiates the start of steps (d) through (j) at each port.

Claim 14

A method in accordance with claim 9 wherein in step (g) each of the time differences is adjusted by a propagation delay from the transmitting port to the first port.

Claim 15

A method in accordance with claim 12 wherein the propagation delay is an estimated delay calculated from the average distance between ports.

Claim 16

A method in accordance with claim 12 wherein the propagation delay that adjusts the time differences in step (g) is calculated separately for each transmitting port and is based for each on the distance between each transmitting port and the first port.

Claim 17

A method in accordance with claim 14 further comprising the steps of identifying the transmitting ports and retrieving the coordinates of the identified transmitting ports from a data base to calculate the distances between the transmitting ports and the first port.

Claim 18

A method in accordance with claim 9 wherein in step (g) only if the quality measure of a downlink signal received from a fixed port is above a predetermined threshold is the timing measure of that downlink signal used to calculate the average of time differences.

Claim 19

In a frequency-reusing radio communications system having a plurality of fixed base units and a plurality of mobile transceivers at least one of said fixed base units being a master base unit which is time synchronized to a common timing reference, each fixed base unit having a transmitter for transmitting a downlink signal at an assigned downlink frequency to at least one mobile transceiver, a receiver for receiving an uplink signal at an associated uplink frequency from at least one mobile transceiver and for receiving downlink signals at all the downlink frequencies being transmitted by the other of the plurality of fixed base units in the system, each fixed base unit transmitting at its assigned downlink frequency a hierarchical value, the hierarchical value of each master base unit being set to a first predetermined hierarchical value and the hierarchical value of each other base unit being initialized with a second hierarchical value, the second hierarchical value being greater than the first hierarchical value, and synchronizing apparatus for synchronizing timing, said synchronizing apparatus in each one of the plurality of base units comprising: means for turning off the transmitter at that one base unit and for tuning the receiver to each possible downlink frequency for synchronizing the timing of that one base unit if that one base unit is not a master base unit; means for measuring the quality of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for measuring the timing of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for determining the hierarchical value of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for determining the timing differences between the measured timing of the downlink signals received at each of the possible downlink frequencies and the timing of the one base unit; means for forming an average time difference of those determined timing differences associated with up to a predetermined number of downlink signals having the highest quality measures of only those downlink signals having the lowest hierarchical value (H L ) if and only if H L is less than or equal to the hierarchical value of said one base unit (H R ); means for setting the hierarchical value of said one base unit to a new value greater than H L if H R is greater than H L ; and means for adjusting the timing of said one base unit in response to the formed average time difference.

Claim 20

In a frequency-reusing radio communications system having a plurality of fixed base units and a plurality of mobile transceivers at least one of said fixed base units being a master base unit which is time synchronized to a common timing reference, each fixed base unit having a transmitter for transmitting a downlink signal at an assigned downlink frequency to at least one mobile transceiver, a receiver for receiving an uplink signal at an associated uplink frequency from at least one mobile transceiver and for receiving downlink signals at all the downlink frequencies being transmitted by the other of the plurality of fixed base units in the system, each fixed base unit transmitting at its assigned downlink frequency a hierarchical value, the hierarchical value of each master base unit being set to a first predetermined hierarchical value and the hierarchical value of each other base unit being initialized with a second hierarchical value, the second hierarchical value being greater than the first hierarchical value, and synchronizing apparatus for synchronizing timing, said synchronizing apparatus in each one of the plurality of base units comprising: means for turning off the transmitter at that one base unit and for tuning the receiver to each possible downlink frequency for synchronizing the timing of that one base unit if that one base unit is not a master base unit; means for measuring the quality of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for measuring the timing of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for determining the hierarchical value of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for determining the timing differences between the measured timing of the downlink signals received at each of the possible downlink frequencies and the timing of the one base unit; means for forming an average time difference of those determined timing differences associated with up to a predetermined number of downlink signals having the highest quality measures of only those downlink signals having the lowest hierarchical value (H L ) if and only if H L is less than or equal to the hierarchical value of said one base unit (H R ); means for setting the hierarchical value of said one base unit to a new value greater than H L if H R is greater than H L ; and means for adjusting the timing of said one base unit in response to the formed average time difference.

Claim 21

A fixed base unit in accordance with claim 17 further comprising control means for controlling when said one base unit synchronizes its timing.

Claim 22

A fixed base unit in accordance with claim 18 wherein said control means repeats synchronizing the timing of said one base unit at randomly spaced times a fixed plurality of times.

Claim 23

A fixed base unit in accordance with claim 17 wherein each of the plurality of fixed base units in the system is connected to a centralized control means, said centralized control means for controlling when each of the plurality of fixed base units synchronizes its timing.

Claim 24

A fixed base unit in accordance with claim 17 wherein said means for determining the timing differences adjusts the timing differences by the propagation delays from the transmitting base units to the said one base unit.

Claim 25

A fixed base unit in accordance with claim 21 wherein each of the propagation delays is an estimated delay calculated from the average distance between fixed base units in the system.

Claim 26

A fixed base unit in accordance with claim 21 wherein each of the propagation delays is calculated separately based on the distances between each of the transmitting base units and the one base unit.

Claim 27

A fixed base unit in accordance with claim 17 wherein said means for forming an average time difference only averages timing differences associated with downlink signals having a quality measure above a predetermined threshold.

Claim 28

In a TDM/TDMA digital telephony system having a plurality of fixed ports and a plurality of mobile portable units, at least one of said ports being a master port which is time synchronized to a common timing reference, each port having a transmitter for transmitting a downlink signal at an assigned downlink frequency to at least one portable unit, a receiver for receiving an uplink signal at an associated uplink frequency from at least one mobile portable unit and for receiving downlink signals at all the downlink frequencies being transmitted by the other of the plurality of ports in the system, each port transmitting at its assigned downlink frequency a hierarchical value, the hierarchical value of each master port being set to a first predetermined hierarchical value and the hierarchical value of each other base unit being initialized with a second hierarchical value, and synchronizing apparatus for synchronizing timing, said synchronizing apparatus in each one of the plurality of ports comprising: means for turning off the transmitter at that one port and for tuning the receiver to each possible downlink frequency for synchronizing the timing of that one port if that one port is not a master port; means for measuring the quality of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of ports in the system when said transmitter is off; means for measuring the timing of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of ports units in the system when said transmitter is off; means for determining the hierarchical value of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for determining the timing differences between the measured timing of the downlink signals received at each of the possible downlink frequencies and the timing of the one port; means for forming an average time difference of those determined timing differences associated with up to a predetermined number of downlink signals having the highest quality measures of only those downlink signals having the lowest hierarchical value (H L ) if and only if H L is less than or equal to the hierarchical value of said one port (H R ); means for setting the hierarchical value of the said one port to a new value greater than H L if H R is greater than H L ; and means for adjusting the timing of said one port in response to the formed average time difference.

Claim 29

In a TDM/TDMA digital telephony system having a plurality of fixed ports and a plurality of mobile portable units, at least one of said ports being a master port which is time synchronized to a common timing reference, each port having a transmitter for transmitting a downlink signal at an assigned downlink frequency to at least one portable unit, a receiver for receiving an uplink signal at an associated uplink frequency from at least one mobile portable unit and for receiving downlink signals at all the downlink frequencies being transmitted by the other of the plurality of ports in the system, each port transmitting at its assigned downlink frequency a hierarchical value, the hierarchical value of each master port being set to a first predetermined hierarchical value and the hierarchical value of each other base unit being initialized with a second hierarchical value, and synchronizing apparatus for synchronizing timing, said synchronizing apparatus in each one of the plurality of ports comprising: means for turning off the transmitter at that one port and for tuning the receiver to each possible downlink frequency for synchronizing the timing of that one port if that one port is not a master port; means for measuring the quality of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of ports in the system when said transmitter is off; means for measuring the timing of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of ports units in the system when said transmitter is off; means for determining the hierarchical value of the downlink signals received at each of the possible downlink frequencies from the other of the plurality of fixed base units in the system when said transmitter is off; means for determining the timing differences between the measured timing of the downlink signals received at each of the possible downlink frequencies and the timing of the one port; means for forming an average time difference of those determined timing differences associated with up to a predetermined number of downlink signals having the highest quality measures of only those downlink signals having the lowest hierarchical value (H L ) if and only if H L is less than or equal to the hierarchical value of said one port (H R ); means for setting the hierarchical value of the said one port to a new value greater than H L if H R is greater than H L ; and means for adjusting the timing of said one port in response to the formed average time difference.

Claim 30

A port in accordance with claim 25 further comprising control means for controlling when said one port synchronizes its timing.

Claim 31

A port in accordance with claim 26 wherein said control means repeats synchronizing the timing of said one port at randomly spaced times a fixed plurality of times.

Claim 32

A fixed base unit in accordance with claim 25 wherein each of the plurality of ports in the system is connected to a centralized control means, said centralized control means for controlling when each of the plurality of ports synchronizes its timing.

Claim 33

A poll in accordance with claim 25 wherein said means for averaging adjusts the differences of the timing of a predetermined number of downlink signals having the highest quality measures and the timing of said one port by the propagation delays to said one port from the other ports transmitting to the said one base unit.

Claim 34

A port in accordance with claim 29 wherein each of the propagation delays is an estimated delay calculated from the average distance between ports in the system.

Claim 35

A port in accordance with claim 29 wherein each of the propagation delays is calculated separately based on the distances between each of the other ports and the one port.

Claim 36

A port in accordance with claim 25 wherein said means for averaging only averages the difference of timing of a downlink signal and the timing of said one base unit if the quality measure of the downlink signal is above a predetermined threshold.