Radio link quality determination in a wireless network
View Patent ↗A method of determining a radio link quality state in a wireless communication system by predicting a signal quality metric of a secondary channel in the absence of the second signal. The predicted signal quality metric may be determined from a received reference signal on a first channel and a measured interference level of the second channel.
1. A method of determining a radio link quality state in a wireless communication system, the method comprising:
measuring at a receiving station a received signal strength of a first channel;
measuring at the receiving station a received interference level of a second channel, wherein the second channel comprises a shared control channel operable to allocate shared channel resources to the receiving station,
predicting at least one quality metric for a hypothetical transmission of the second channel using a plurality of parameters, including:
the received signal strength of the first channel;
the received interference level of the second channel; and
an adjustment parameter, wherein the adjustment parameter is based upon the difference between a first transmit power level of a first signal transmitted on the first channel and a potential transmit power level of a second signal transmitted on the second channel; and
identifying the radio link quality state based upon the at least one quality metric and further based upon an acceptable radio link quality level.
2. The method of claim 1 , wherein the radio link quality state comprises a failed state in response to the at least one quality metric being below the acceptable radio link quality level.
3. The method of claim 1 , wherein the at least one quality metric includes a signal-to-noise-plus-interference ratio (SNIR) of the second channel, a signal-to-noise ratio (SNR) of the second channel, or a combination thereof.
4. The method of claim 1 , wherein predicting at least one quality metric of the second channel includes combining:
the received signal strength of the first channel;
a negative of the received interference level of the second channel; and
the difference between the first transmit power level of the first signal transmitted on the first channel and the second transmit power level of the second signal transmitted on the second channel.
5. The method of claim 1 , wherein at least one of the plurality of parameters is wirelessly signaled from a network to a mobile terminal.
6. The method of claim 1 , wherein at least one of the plurality of parameters is wirelessly broadcast from a network to a plurality of mobile terminals.
7. The method of claim 1 , wherein at least one of the plurality of parameters is a constant value.
8. The method of claim 1 , wherein the identifying the radio link quality state includes computing a statistic from multiple determinations of the predicted quality metric.
9. The method of claim 8 , wherein the identifying the radio link quality state further includes:
comparing the statistic to a threshold value; and
setting the radio link quality state based on the comparison.
10. The method of claim 1 , wherein the first channel is a channel having a constant transmit power level over a period.
11. The method of claim 1 , wherein the first channel is transmitted within a first time slot period and the second channel is transmitted within a second time slot period different than the first time slot period.
12. The method of claim 1 , wherein the first channel is transmitted with a first code and the second channel is transmitted with a second code different than the first code.
13. The method of claim 1 , wherein the first channel includes a beacon channel.
14. The method of claim 1 , wherein the second channel communicates channel allocation messages.
15. The method of claim 1 , wherein at least one of the plurality of parameters is formed from a series of values.
16. The method of claim 15 , wherein the at least one of the plurality of parameters is formed from by an averaging process of the series of values.
17. A method of predicting a radio link quality state on a secondary channel in a wireless communication system between a network and a mobile terminal, wherein the secondary channel is used intermittently as a control channel, the method comprising:
comparing a threshold value to a plurality of calculated values, wherein each of the plurality of calculated values is sequentially formed by:
measuring at the mobile terminal a reference level of signal strength received by the mobile terminal on a reference channel;
measuring at the mobile terminal, within a period, a level of noise-plus-interference received by the mobile terminal on the secondary channel; and
providing the computed value as the difference of the reference level of signal strength, the level of noise-plus-interference received, and an attenuation of a transmit power level, wherein the attenuation of a transmit power level represents an attenuation of a transmit power level of a signal transmitted on the secondary channel relative to a transmit power level of signal transmitted on the reference channel;
determining a number of the plurality of calculated values that are past the threshold value; and
setting the radio link quality state if the determined number exceeds a preset constant.
18. The method of claim 17 , wherein the each of the plurality of calculated values is further formed by determining whether the secondary channel was free of control messages during the period, and if the secondary channel was free of the control channel messages during the period providing the computed value.
19. The method of claim 17 , wherein providing the computed value is represented by S reference −I secondary −D, wherein
S reference is the noise-plus-interference received by the mobile terminal on the secondary channel,
I secondary is the noise-plus-interference received by the mobile terminal on the secondary channel, and
D is the attenuation of the transmit power level.