Inter-system cell reselection in TD-SCDMA systems

Patent metadata

Field	Value
Publication number	US-9807663-B2
Application number	US-201213565410-A
Country	US
Kind code	B2
Filing date	Aug 2, 2012
Priority date	Mar 21, 2012
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

When a user equipment performs inter-cell measurement, it may desire to measure signal quality and signal level of a source radio access technology (RAT) cell and a target cell. The signal quality measurement may be Squal and the signal level measurement may be Srxlev. Because Squal is not defined for TD-SCDMA, a new measurement criteria is defined to allow proper comparison of source RAT cell measurements with target RAT cell measurements when a user equipment is considering switching to a target cell.

First claim

What is claimed is:

1. A method for wireless communication at a user equipment (UE), comprising:
measuring a signal strength of a common channel of a source radio access technology (RAT) cell for cell reselection from the source RAT cell to a target RAT cell when the UE is in an idle mode, a cell paging channel state, or a UTRAN Registration Area (URA) paging channel state, in which the source RAT cell is a serving cell and a time division-synchronous code division multiple access (TD-SCDMA) cell, in which a reselection criteria of the target RAT cell includes signal strength evaluation and signal quality evaluation and in which a reselection criteria of the source RAT cell includes the signal strength evaluation and not the signal quality evaluation, the source RAT cell having a source priority;
measuring a received signal quality metric of a common pilot signal of the target RAT cell in accordance with the reselection criteria of the target RAT cell, the target RAT cell having a target priority; and
performing an adjusted cell reselection evaluation procedure based at least in part on the signal strength of the common channel of the source RAT cell and the received signal quality metric of the common pilot signal of the target RAT cell when the target priority is lower than the source priority by comparing the signal strength of the common channel of the source RAT cell to a first threshold and the received signal quality metric of the common pilot signal of the target RAT cell to a second threshold.

2. The method of claim 1 , further comprising receiving the first threshold and the second threshold from a network.

3. The method of claim 1 , in which the measuring the received signal quality metric of the common pilot signal of the target RAT cell occurs when the UE is in the idle mode or the cell paging channel state, or the URA paging channel state.

4. The method of claim 1 , in which the target RAT cell is a Long Term Evolution (LTE) cell.

5. The method of claim 1 , wherein the adjusted cell reselection evaluation procedure is performed without an evaluation of a signal quality metric of the source RAT.

6. The method of claim 5 , wherein a cell reselection is performed without reference to a signal strength of the target RAT.

7. The method of claim 1 , wherein the adjusted cell
reselection evaluation procedure is performed without reference to a signal strength of the target RAT.

8. A user equipment (UE) for wireless communication, comprising:
means for measuring a signal strength of a common channel of a source radio access technology (RAT) cell for cell reselection from the source RAT cell to a target RAT cell when the UE is in an idle mode, a cell paging channel state, or a UTRAN Registration Area (URA) paging channel state, in which the source RAT cell is a serving cell and a time division-synchronous code division multiple access (TD-SCDMA) cell, in which a reselection criteria of the target RAT cell includes signal strength evaluation and signal quality evaluation and in which a reselection criteria of the source RAT cell includes the signal strength evaluation and not the signal quality evaluation, the source RAT cell having a source priority;
means for measuring a received signal quality metric of a common pilot signal of the target RAT cell in accordance with the reselection criteria of the target RAT cell, the target RAT cell having a target priority; and
means for performing an adjusted cell reselection evaluation procedure based at least in part on the signal strength of the common channel of the source RAT cell and the received signal quality metric of the common pilot signal of the target RAT cell when the target priority is lower than the source priority by comparing the signal strength of the common channel of the source RAT cell to a first threshold and the received signal quality metric of the common pilot signal of the target RAT cell to a second threshold.

9. The UE of claim 8 , in which the measuring of the received signal quality metric of the common pilot signal for the target RAT cell occurs when the UE is in the idle mode or the cell paging channel state, or the URA paging channel state.

10. A non-transitory computer-readable medium having program code which, when executed by at least one processor at a user equipment (UE), causes the at least one processor:
to measure a signal strength of a common channel of a source radio access technology (RAT) cell for cell reselection from the source RAT cell to a target RAT cell when the UE is in an idle mode, a cell paging channel state, or a UTRAN Registration Area (URA) paging channel state, in which the source RAT cell is a serving cell and a time division-synchronous code division multiple access (TD-SCDMA) cell, in which a reselection criteria of the target RAT cell includes signal strength evaluation and signal quality evaluation and in which a reselection criteria of the source RAT cell includes the signal strength evaluation and not the signal quality evaluation, the source RAT cell having a source priority;
to measure a received signal quality metric of a common pilot signal of the target RAT cell in accordance with the reselection criteria of the target RAT cell, the target RAT cell having a target priority; and
to perform an adjusted cell reselection evaluation procedure based at least in part on the signal strength of the common channel of the source RAT cell and the received signal quality metric of the common pilot signal of the target RAT cell when the target priority is lower than the source priority by comparing the signal strength of the common channel of the source RAT cell to a first threshold and the received signal quality metric of the common pilot signal of the target RAT cell to a second threshold.

11. The non-transitory computer-readable medium of claim 10 , in which the at least one processor is further configured to measure the received signal quality metric of the common pilot signal for the target RAT cell when the UE is in the idle mode or the cell paging channel state, or the URA paging channel state.

12. A user equipment (UE) for wireless communication, comprising: a memory; and
at least one processor coupled to the memory, the at least one processor being configured:
to measure a signal strength of a common channel of a source radio access technology (RAT) cell for cell reselection from the source RAT cell to a target RAT cell when the UE is in an idle mode, a cell paging channel state, or a UTRAN Registration Area (URA) paging channel state, in which the source RAT cell is a serving cell and a time division-synchronous code division multiple access (TD-SCDMA) cell, in which a reselection criteria of the target RAT cell includes signal strength evaluation and signal quality evaluation and in which a reselection criteria of the source RAT cell includes the signal strength evaluation and not the signal quality evaluation, the source RAT cell having a source priority;
to measure a received signal quality metric of a common pilot signal of the target RAT cell in accordance with the reselection criteria of the target RAT cell, the target RAT cell having a target priority; and
to perform an adjusted cell reselection evaluation procedure based at least in part on the signal strength of the common channel of the source RAT cell and the received signal quality metric of the common pilot signal of the target RAT cell when the target priority is lower than the source priority by comparing the signal strength of the common channel of the source RAT cell to a first threshold and the received signal quality metric of the common pilot signal of the target RAT cell to a second threshold.

Assignees

• Mandadapu Krishna Rao
• Gopal Thawatt
• Qualcomm Inc

Inventors

• Mandadapu Krishna Rao
• Gopal Thawatt

Classifications

• H04W36/0094 Primary

  Definition of hand-off measurement parameters · CPC title

• H04W36/1446

  wherein at least one of the networks is unlicensed · CPC title

• H04W36/304 Primary

  due to measured or perceived resources with higher communication quality · CPC title

• H04W36/14

  Reselecting a network or an air interface · CPC title

• H04W36/30 Primary

  by measured or perceived connection quality data · CPC title