Signal measurement on component carriers in wireless communication systems
A method in a wireless communication device includes performing measurements of a first serving cell on a first carrier frequency at a first rate, determining whether a signal level of a second serving cell on a second carrier frequency exceeds a threshold, and performing measurements of the first serving cell at a second rate if the signal level of the second serving cell is below the threshold, wherein the second rate is higher than the first rate.
1. A method in a wireless communication device, the method comprising:
measuring a signal of a primary serving cell carrier signal;
measuring a signal of a deactivated component carrier of a secondary serving cell at a first rate;
determining a difference between the primary serving cell carrier signal and a neighboring cell carrier signal;
if the determined difference between the primary serving cell carrier signal and the neighboring cell carrier signal is higher than a threshold value, measuring the signal of the deactivated secondary component carrier of the secondary serving cell at a second rate, the second rate being higher than the first rate;
receiving a measurement reporting offset from a base station; and
if the determined difference is higher than the measurement reporting offset, reporting the measured signal to the base station.
2. The method of claim 1 further comprising receiving, in response to the reporting step, a handover command from the base station.
3. The method of claim 2 wherein the handover command is a command for the wireless communication device to handover from the primary serving cell to the neighboring cell.
4. The method of claim 2 :
wherein the secondary cell becomes activated; and
wherein the handover command is a command for the wireless communication device to handover from the primary serving cell to the activated secondary serving cell.
5. The method of claim 1 further comprising:
determining, based on the measured deactivated secondary component carrier signal, that the wireless communication device should handover from the primary serving cell; and
performing a handover from the primary serving cell based on the handover determination.
6. The method of claim 1 , wherein the signal of the primary serving cell carrier signal is measured by:
generating a first averaged signal measurement on a first carrier frequency;
producing a first filter output based on the first averaged signal measurement weighted by a first weight;
generating a second averaged signal measurement on the first carrier frequency; and
producing a second filter output based on the first filter output and based on the second averaged signal measurement weighted by a second weight.
7. The method of claim 6 , wherein the first averaged signal measurement is based on a first averaging period, the second averaged signal measurement is based on a second averaging period, and the first weight is less than the second weight if the second averaging period is greater than a threshold.
8. The method of claim 1 , wherein the primary serving cell and the secondary serving cell are provided by a same base unit.
9. The method of claim 1 wherein the measured signal is reported to the base station at the second rate when the determined difference is higher than the measurement reporting offset.