Adaptive modulation control system and wireless communication apparatus
View Patent ↗Object To reduce deterioration of transmission quality under circumstances where the moving speed is high. Overcoming Means An adaptive modulation control apparatus for adaptively selecting a modulation parameter from among a plurality of modulation parameters determined based on a plurality of modulation schemes, coding rates of error correction or a combination thereof corresponding to a propagation path state is provided with a reception state measuring section ( 2 ) that measures a reception state of a signal received from a communicating apparatus, a correcting section ( 3 ) that makes a correction to change propagation path information indicative of a measurement result of the propagation path state based on the measured reception state, and a modulation parameter selecting section ( 4 ) that selects a modulation parameter corresponding to the corrected propagation path information.
1. An adaptive modulation control system comprising:
a reception state measuring section that calculates a first reception state determined based on reception power of a signal received from a communicating party, or a second reception state indicated by a ratio or difference between the first reception state and a criterion value;
a correcting section that makes a correction of at least one of changing propagation path information indicative of a measurement result of a propagation path state to make the propagation path information poorer as the first or the second reception state is higher, and of changing the propagation path information to make the propagation path information better as the first or the second reception state is lower, based on the first or the second reception state; and
a modulation parameter selecting section that selects a modulation parameter corresponding to the corrected propagation path information.
2. The adaptive modulation control system according to claim 1 , wherein the propagation path state is determined by one of reception power, a signal to noise power ratio, a signal to interference and noise power ratio, carrier power, a carrier to noise power ratio, and a carrier to interference and noise power ratio.
3. The adaptive modulation control system according to claim 1 , wherein the reception state measuring section uses, as the first reception state, one of reception power, a signal to noise power ratio, a signal to interference and noise power ratio, carrier power, a carrier to noise power ratio, and a carrier to interference and noise power ratio.
4. The adaptive modulation control system according to claim 1 , wherein the reception state measuring section calculates, as the second reception state, one of a ratio or difference between reception power and a criterion value, a ratio or difference between a signal to noise power ratio and a criterion value, a ratio or difference value between a signal to interference and noise power ratio and a criterion value, a ratio or difference between carrier power and a criterion value, a ratio or difference between a carrier to noise power ratio and a criterion value, and a ratio or difference between a carrier to interference and noise power ratio and a criterion value.
5. The adaptive modulation control system according to claim 1 , wherein the criterion value is one of a mean value, median value and minimum value of the reception power, signal to noise power ratio, signal to interference and noise power ratio, carrier power, carrier to noise power ratio, or carrier to interference and noise power ratio in a plurality of points in the time axis direction, when respective one of the reception power, signal to noise power ratio, signal to interference and noise power ratio, carrier power, carrier to noise power ratio, and carrier to interference and noise power ratio is expressed by a function of time.
6. The adaptive modulation control system according to claim 1 , wherein one of a mean value, median value and minimum value in the frequency axis direction is used as the criterion value when respective one of the reception power, signal to noise power ratio, signal to interference and noise power ratio, carrier power, carrier to noise power ratio, and carrier to interference and noise power ratio is expressed by a function of frequency, and the system is applied to multicarrier wireless communication.
7. The adaptive modulation control system according to claim 1 , wherein one of a mean value, median value and minimum value in the time axis direction and the frequency axis direction is used as the criterion value when one of the reception power, signal to noise power ratio, signal to interference and noise power ratio, carrier power, carrier to noise power ratio, and carrier to interference and noise power ratio is expressed by a function of time and frequency, and the system is applied to multicarrier wireless communication.
8. The adaptive modulation control system according to claim 4 , wherein the correcting section determines reception quality of the received signal, and according to a determination result, changes the criterion value.
9. A wireless communication apparatus applied to the adaptive modulation control system as described in claim 1 , comprising:
functions of transmitting and receiving radio signals,
wherein the apparatus transmits or receives any one of propagation path information indicative of a measurement result of the propagation path state from a communicating party, propagation path information indicative of an estimation result of the propagation path state in transmission in the communicating party, propagation path information indicative of a measurement result of the propagation path state subsequent to the correction, propagation path information indicative of an estimation result of the propagation path state in transmission subsequent to the correction in the communicating party, and modulation parameter information indicative of a selected modulation parameter.