Method of managing use of channelization codes during soft handoff
View Patent ↗In one embodiment of managing the use of channelization codes during soft handoff of a mobile station from a transferring network station to a candidate network station, a determination is made as to whether a field associated with an existing channelization code used by the candidate network station is unused and meets timing criteria associated with a corresponding field received by the mobile station from the transferring network station. Based on this determination, a channelization code for use by the candidate network station in communicating with the mobile station is assigned.
1. A method of managing use of channelization codes during soft handoff of a mobile station from a transferring network station to a candidate network station, comprising:
determining if a transport power control (TPC) field associated with an existing channelization code used by the candidate network station is unused and meets timing criteria associated with a corresponding TPC field received by the mobile station from the transferring network station; and
assigning a channelization code for use by the candidate network station in communicating with the mobile station based on the determining step.
2. The method of claim 1 , wherein the assigning step assigns the existing channelization code if the determining step determines that a TPC field associated with the existing channelization code used by the candidate network station is unused and meets timing criteria associated with the corresponding TPC field received by the mobile station from the transferring network station.
3. The method of claim 2 , wherein the timing criteria is met if an unused TPC field of the existing channelization code is received by the mobile station within a timing window established with respect to receipt of the corresponding TPC field from the transferring network station.
4. The method of claim 3 , wherein the timing window is +148 chips to −148 chips with respect to receipt of the corresponding TPC field from the transferring network station.
5. The method of claim 2 , further comprising:
sending, from the candidate network station, forward link communication channel data during the TPC field of the existing channelization code if the assigning step assigns the existing channelization code.
6. The method of claim 5 , wherein the forward link communication channel is a Fractional Dedicated Physical Channel.
7. The method of claim 2 , wherein the assigning step assigns an unused channelization code for use by the candidate network station only if the determining step does not determine that a TPC field associated with the existing channelization code used by the candidate network station is unused and meets timing criteria associated with the corresponding TPC field received by the mobile station from the transferring network station.
8. The method of claim 1 , wherein the assigning step assigns an unused channelization code for use by the candidate network station only if the determining step does not determine that a TPC field associated with the existing channelization code used by the candidate network station is unused and meets timing criteria associated with the corresponding TPC field received by the mobile station from the transferring network station.
9. The method of claim 1 , wherein the timing criteria is met if an unused TPC field of the existing channelization code is received by the mobile station within a timing window established with respect to receipt of the corresponding TPC field from the transferring network station.
10. The method of claim 1 , after the assigning step, further comprising:
detecting if a timing between a TPC field of the assigned channelization code that corresponds to the corresponding TPC field received by the mobile station from the transferring network station has drifted beyond an acceptable timing window with respect to the corresponding TPC field; and
repeating the determining and assigning steps if the detecting step detects that the timing between the TPC field of the assigned channelization code that corresponds to the corresponding TPC field received by the mobile station from the transferring network station has drifted beyond an acceptable timing window with respect to the corresponding TPC field.
11. The method of claim 10 , wherein the detecting step comprises:
determining a timing difference between the TPC field of the assigned channelization code and the corresponding TPC field received by the mobile station from the transferring network station; and
detecting drift beyond an acceptable timing window if the absolute value of the timing difference exceeds a threshold amount.
12. The method of claim 1 , after the assigning step, further comprising:
detecting a lack of acceptable synchronization between (i) a TPC field of the assigned channelization code that corresponds to the corresponding TPC field received by the mobile station from the transferring network station and (ii) the corresponding TPC field received by the mobile station from the transferring network station; and
repeating the determining and assigning steps if the detecting step detects a lack of acceptable synchronization.
13. The method of claim 1 , further comprising:
discriminating whether one channelization code used by the candidate network station has an unused TPC field that meets timing criteria associated with a corresponding used TPC field of another used channelization code used by the candidate network; and
using the unused TPC field of the one channelization code instead of the used TPC field of the another used channelization code such that the used TPC field of the one channelization code becomes unused if the discriminating step determines that the another used channelization code has an unused TPC field that meets timing criteria associated with a corresponding used TPC field of the one channelization code.
14. A method of managing use of channelization codes, comprising:
discriminating whether one channelization code used by a candidate network station has an unused transport power control (TPC) field that meets timing criteria associated with a corresponding used TPC field of another used channelization code used by the candidate network; and
using the unused TPC field of the one channelization code instead of the used TPC field of the another used channelization code such that the used TPC field of the one channelization code becomes unused if the discriminating step determines that the another used channelization code has an unused TPC field that meets timing criteria associated with a corresponding used TPC field of the one channelization code.