Frequency quality criteria for inter-frequency handover in a TD-CDMA communication system
A method for determining whether to perform handover of a UE apparatus to a candidate cell and carrier frequency of a TD-CDMA telecommunications network (such as a TD-SCDMA network) based separately on coverage and capacity, using one decision metric for coverage (e.g. based on received signal code power for the candidate cell and carrier frequency) and a different decision metric for capacity (e.g. based on a quantity proportional to the received signal code power for the candidate cell and carrier frequency and inversely proportional to a measure of total interference in the candidate cell on the carrier frequency. Corresponding equipment and a computer program product are also provided. In deciding whether handover is needed based on capacity, a threshold for received signal code power may be used in addition to the metric for capacity.
1. A method comprising:
receiving from a cellular communication system providing time division code division multiple access an indication that a handover measurement is to be performed and that an indicated decision metric is to be used in ranking cells and corresponding carrier frequencies for possible handover; and
performing, at a communication device, a handover measurement and ranking, at the communication device, results for different cells and carrier frequencies according to the indicated decision metric;
wherein the indicated decision metric is either a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.
2. A method as in claim 1 , wherein the first decision metric varies in direct proportion to a received signal code power for a cell and carrier frequency.
3. A non-transitory computer-readable medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:
receiving an indication that a handover measurement is to be performed and that an indicated decision metric is to be used in ranking cells and frequencies for possible handover; and
performing the handover measurement and ranking results for different cells and frequencies according to the indicated decision metric;
wherein the indicated decision metric is a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.
4. A user equipment apparatus comprising:
equipment for communicatively coupling to a cellular communication system providing time division code division multiple access;
means for receiving an indication that a handover measurement is to be performed and that an indicated decision metric is to be used in ranking cells and corresponding carrier frequencies for possible handover; and
means for performing the handover measurement and ranking results for different cells and carrier frequencies according to the indicated decision metric;
wherein the indicated decision metric is either a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.
5. A user equipment apparatus as in claim 4 , wherein the first decision metric varies in direct proportion to a received signal code power for a cell and carrier frequency.
6. A user equipment apparatus comprising:
equipment to communicatively couple to a cellular communication system providing time division code division multiple access; and
to receive an indication that a handover measurement is to be performed and that an indicated decision metric is to be used in ranking cells and corresponding carrier frequencies for possible handover; and
a determination module configured to perform the handover measurement and rank results for different cells and carrier frequencies according to the indicated decision metric;
wherein the decision metric is either a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.
7. A user equipment apparatus as in claim 6 , wherein the first decision metric varies in direct proportion to a received signal code power for a cell and carrier frequency.
8. A user equipment apparatus as in claim 6 , wherein the determination module is further configured to compare a received signal code power to a threshold for the received signal code power.
9. A method comprising:
receiving a message including an indication that an interfrequency measurement is to be performed and that an indicated decision metric is to be used in ranking cells and frequencies; and
performing, at a communication device, the interfrequency measurement and ranking, at the communication device, results for different cells and frequencies according to the indicated decision metric;
wherein the indicated decision metric is indicated to be either a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.
10. A non-transitory computer-readable medium having instructions stored thereon that, if executed by a computing device, cause the computing device to perform operations comprising:
receiving a message including an indication that an interfrequency measurement is to be performed and that an indicated decision metric is to be used in ranking cells and frequencies; and
performing an interfrequency measurement and ranking results for different cells and frequencies according to the indicated decision metric;
wherein the indicated decision metric is indicated to be either a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.
11. A user equipment apparatus comprising:
means for receiving a message including an indication that an interfrequency handover is to be performed and that an indicated decision metric is to be used in ranking cells and frequencies; and
means for performing an interfrequency handover and ranking results for different cells and frequencies according to the indicated decision metric;
wherein the indicated decision metric is indicated to be either a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.
12. A user equipment apparatus comprising:
equipment to receive a message including an indication that an interfrequency handover is to be performed and that an indicated decision metric is to be used in ranking cells and frequencies; and
a determination module configured to perform an interfrequency handover and rank results for different cells and frequencies according to the indicated decision metric;
wherein the indicated decision metric is indicated to be either a first decision metric related to capacity or a second decision metric related to coverage; and
wherein the first decision metric varies in inverse proportion to a difference between a received signal strength indicator for the cell and carrier frequency and a received signal code power for the cell and carrier frequency or to a quantity algebraically related to the difference.