Wireless communication apparatus and method

• US 20070201344A1
• Filed: 01/17/2007
• Published: 08/30/2007
• Est. Priority Date: 01/26/2006
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Miyabayashi, Naoki
• Granted Patent: US 8,457,675 B2
• Time in Patent Office: Days
• US Class Current: 370/203
• CPC Class Codes: H04L 5/0044 allocation of payload

Abstract

A wireless communication apparatus that transmits and receives an orthogonal frequency division multiplexing signal to communicate with a communication counterpart, the wireless communication apparatus including measurement means for measuring the signal level of each subcarrier of the reception signal received from the communication counterpart, calculation means for calculating a predicted signal level of each subcarrier when the communication counterpart receives the signal based on the signal level of each subcarrier of the reception signal measured by the measurement means and calculating an increase/decrease rate of transmission power for each subcarrier such that the average amount of limited mutual information limited by the modulation method for the signal is maximized based on the predicted signal level, and transmission parameter control means for controlling transmission parameters including the increase/decrease rate of transmission power for each subcarrier calculated by the calculation means.

Claims

1. A wireless communication apparatus that transmits and receives an orthogonal frequency division multiplexing signal to communicate with a communication counterpart, the wireless communication apparatus comprising:

measurement means for measuring the signal level of each subcarrier of the reception signal received from the communication counterpart;

calculation means for calculating a predicted signal level of each subcarrier when the communication counterpart receives the signal based on the signal level of each subcarrier of the reception signal measured by the measurement means and calculating an increase/decrease rate of transmission power for each subcarrier such that the average amount of limited mutual information limited by the modulation method for the signal is maximized based on the predicted signal level; and

transmission parameter control means for controlling transmission parameters including the increase/decrease rate of transmission power for each subcarrier calculated by the calculation means.

2. The wireless communication apparatus according to claim 1, wherein the calculation means uses the following equation (1) to identify a subcarrier i in which the increase/decrease rate Pti of the transmission power is zero, and uses predicted signal level γ

i of every other subcarrier i to recalculate the following equation (1) so as to calculate the increase/decrease rate Pti of the transmission power for each subcarrier i of the signal;

$\begin{array}{cc}{\mathrm{Pt}}_i=\frac{\log <br><br>\left({\mathrm{\gamma <br><br>}}_i^{h_M}\right)}{m_M·<br><br>{\mathrm{\gamma <br><br>}}_i^{h_M}}-\frac{\underset{i=1}{\overset{N}{\sum <br><br>}}<br><br>\frac{\log <br><br>\left({\mathrm{\gamma <br><br>}}_i^{h_M}\right)}{m_M·<br><br>{\mathrm{\gamma <br><br>}}_i^{h_M}}-N}{\sum <br><br>\frac{1}{{\mathrm{\gamma <br><br>}}_i^{h_M}}}·<br><br>\frac{1}{{\mathrm{\gamma <br><br>}}_i^{h_M}}& \left(1\right)\end{array}$

where M is the constellation number, and mM and hM are coefficients that depend on M.

3. The wireless communication apparatus according to claim 1, wherein the measurement means measures the packet error rate of the reception signal received from the communication counterpart, and

the calculation means corrects the average amount of signal attenuation based on the comparison result of the packet error rate measured by the measurement means and a predicted packet error rate when the communication counterpart receives the signal, and corrects the predicted signal level based on the average amount of attenuation.

4. The wireless communication apparatus according to claim 3, wherein the calculation means uses the signal level or the packet error rate measured by the measurement means to calculate the power amplification factor, the modulation method and the error correction code rate of the signal.

5. A wireless communication apparatus that transmits and receives an orthogonal frequency division multiplexing signal to communicate with a communication counterpart, the wireless communication apparatus comprising:

measurement means for measuring the signal level of each subcarrier of the reception signal received from the communication counterpart;

calculation means for calculating a predicted signal level of each subcarrier when the communication counterpart receives the signal based on the signal level of each subcarrier of the reception signal measured by the measurement means, calculating a threshold value based on the predicted signal level and calculating an increase/decrease rate of transmission power for each subcarrier of the signal based on the comparison result of the threshold value and the predicted signal level; and

transmission parameter control means for controlling transmission parameters including the increase/decrease rate of transmission power for each subcarrier calculated by the calculation means.

6. The wireless communication apparatus according to claim 5, wherein the calculation means calculates the increase/decrease rate of transmission power for each subcarrier such that transmission power for a subcarrier whose predicted signal level is smaller than the threshold value is zero and transmission power for the remaining subcarriers is uniform.

7. The wireless communication apparatus according to claim 5, wherein the measurement means measures the packet error rate of the reception signal received from the communication counterpart, and

the calculation means corrects the average amount of signal attenuation based on the comparison result of the packet error rate measured by the measurement means and a predicted packet error rate when the communication counterpart receives the signal, and corrects the predicted signal level based on the average amount of attenuation.

8. The wireless communication apparatus according to claim 7, wherein the calculation means uses the signal level or the packet error rate measured by the measurement means to calculate the power amplification factor, the modulation method and the error correction code rate of the signal.

9. A wireless communication method for transmitting and receiving an orthogonal frequency division multiplexing signal to communicate with a communication counterpart, the wireless communication method comprising the steps of:

measuring the signal level of each subcarrier of the reception signal received from the communication counterpart;

calculating a predicted signal level of each subcarrier when the communication counterpart receives the signal based on the signal level of each subcarrier of the reception signal measured at the measuring step and calculating an increase/decrease rate of transmission power for each subcarrier such that the average amount of limited mutual information limited by the modulation method for the signal is maximized based on the predicted signal level; and

controlling transmission parameters including the increase/decrease rate of transmission power for each subcarrier calculated at the calculating step.

10. A wireless communication method for transmitting and receiving an orthogonal frequency division multiplexing signal to communicate with a communication counterpart, the wireless communication method comprising the steps of:

measuring the signal level of each subcarrier of the reception signal received from the communication counterpart;

calculating a predicted signal level of each subcarrier when the communication counterpart receives the signal based on the signal level of each subcarrier of the reception signal measured at the measuring step, calculating a threshold value based on the predicted signal level and calculating an increase/decrease rate of transmission power for each subcarrier based on the comparison result of the threshold value and the predicted signal level; and

controlling transmission parameters including the increase/decrease rate of transmission power for each subcarrier calculated at the calculating step.

11. A wireless communication apparatus that transmits and receives an orthogonal frequency division multiplexing signal to communicate with a communication counterpart, the wireless communication apparatus comprising:

a measuring unit measuring the signal level of each subcarrier of the reception signal received from the communication counterpart;

a calculator calculating a predicted signal level of each subcarrier when the communication counterpart receives the signal based on the signal level of each subcarrier of the reception signal measured by the measuring unit and calculating an increase/decrease rate of transmission power for each subcarrier such that the average amount of limited mutual information limited by the modulation method for the signal is maximized based on the predicted signal level; and

a transmission parameter controller controlling transmission parameters including the increase/decrease rate of transmission power for each subcarrier calculated by the calculator.

12. A wireless communication apparatus that transmits and receives an orthogonal frequency division multiplexing signal to communicate with a communication counterpart, the wireless communication apparatus comprising:

a measuring unit measuring the signal level of each subcarrier of the reception signal received from the communication counterpart;

a calculator calculating a predicted signal level of each subcarrier when the communication counterpart receives the signal based on the signal level of each subcarrier of the reception signal measured by the measuring unit, calculating a threshold value based on the predicted signal level and calculating an increase/decrease rate of transmission power for each subcarrier of the signal based on the comparison result of the threshold value and the predicted signal level; and

a transmission parameter controller controlling transmission parameters including the increase/decrease rate of transmission power for each subcarrier calculated by the calculator.