Wireless communication apparatus and wireless communication method

1. A wireless communication apparatus, comprising:

a demodulation unit operable to demodulate a received signal to obtain demodulated data;

a link information management unit operable (i) to extract received-signal strength information and required-CIR information from the demodulated data, (ii) to obtain a CIR estimate value by estimating a CIR of a second wireless station in a case where the wireless communication apparatus interferes with the second wireless station based on the extracted received-signal strength information, and (iii) to judge whether or not a link of the received signal is concurrently allowable with a link of a signal to be transmitted based on the required-CIR information and the CIR estimate value, where the link of the received signal is data transmission between a first wireless station and the second wireless station;

a concurrent transmission link management unit operable (i) to store therein, when the link information management unit judges that the link of the received signal is concurrently allowable with the link of the signal to be transmitted, wireless station identifier information, included in the demodulated data, of the link of the received signal, (ii) to judge whether or not the link of the received signal is concurrently allowable with the link of the signal to be transmitted by comparing the wireless station identifier information of the link of the received signal with wireless station identifier information of links of previously received signals, each of which having been stored in the concurrent transmission link management unit based on a result of a judgment by the link information management unit, and (iii) to generate and output a concurrent transmission timing signal based on a result of the judgment by the concurrent transmission link management unit; and

a transmission unit operable to transmit a signal according to a timing that overlaps reception of the received signal based on the concurrent transmission timing signal received from the concurrent transmission link management unit.

2. The wireless communication apparatus of claim 1 , further comprising

a received-signal strength detection unit operable to measure a signal strength of the received signal, and to generate received-signal strength information of the received signal,

wherein the link information management unit (i) extracts transmission power information from the demodulated data, (ii) estimates a received-signal strength in a case where the signal transmitted by the wireless communication apparatus is received by the second wireless station based on the received-signal strength information and the transmission power information, (iii) obtains a CIR estimate value by estimating a CIR of the second wireless station in a case where the wireless communication apparatus interferes with the second wireless station based on the extracted received-signal strength information and the estimated received-signal strength, and (iv) judges whether the link of the received signal is allowable based on the required-CIR information and the CIR estimate value.

3. The wireless communication apparatus of claim 1 , wherein

the concurrent transmission link management unit adjusts a length of a packet to be subject to concurrent transmission such that transmission of the packet to be subject to concurrent transmission completes substantially at the same time as transmission of a packet being transmitted by the first wireless station based on packet length information included in the demodulated data.

4. The wireless communication apparatus of claim 1 , further comprising

a received-signal strength detection unit operable to measure a signal strength of the received signal, and to generate received-signal strength information of the received signal,

wherein, if the transmission unit does not receive the concurrent transmission timing signal, the transmission unit (i) performs carrier sense based on the received-signal strength information generated by the received-signal strength detection unit, and (ii) judges whether to perform transmission based on a result of the carrier sense, and

wherein, if the transmission unit does receive the concurrent transmission timing signal, the transmission unit performs transmission based on the concurrent transmission timing signal regardless of the received-signal strength information generated by the received-signal strength detection unit.

5. A wireless communication method used by a first wireless station and a second wireless station communicating with each other, wherein

the second wireless station measures a received-signal strength of a signal transmitted by a third wireless station to a fourth wireless station, stores therein the received-signal strength as received-signal strength information of the third wireless station, and includes the received-signal strength information of the third wireless station into a signal addressed to the first wireless station and transmits the signal to the first wireless station, and

the first wireless station extracts link parameter information included in a signal transmitted by the fourth wireless station to the third wireless station, judges whether a transmission link from the third wireless station to the fourth wireless station and a transmission link from the first wireless station to the second wireless station are compatible in concurrent transmission without interference with each other based on the received-signal strength information of the third wireless station received from the second wireless station and the extracted link parameter information, and if judging affirmatively and receiving a header of the signal transmitted by the third wireless station to the fourth wireless station, transmits a signal to the second wireless station according to a timing that overlaps transmission of the signal that is being transmitted by the third wireless station.

6. The wireless communication method of claim 5 , wherein

the link parameter information includes received-signal strength information of a signal transmitted by the third wireless station to the fourth wireless station, transmission power information of the fourth wireless station, and required-CIR information showing a CIR required for the fourth wireless station to receive the signal transmitted by the third wireless station, and

the first wireless station estimates a CIR of the forth wireless station based on the link parameter information, and compares the CIR with the required-CIR information to judge whether the transmission link from the third wireless station to the fourth wireless station and the transmission link from the first wireless station to the second wireless station are compatible in concurrent transmission without interference with each other.

7. The wireless communication method of claim 6 , wherein

the first wireless station estimates the CIR of the fourth wireless station based on the received-signal strength information of the fourth wireless station obtained by measuring a received-signal strength of a signal transmitted by the fourth wireless station to the third wireless station, the received-signal strength information of the signal transmitted by the third wireless station to the fourth wireless station and the transmission power information of the fourth wireless station which are included in the link parameter information, and transmission power information of the first wireless station.

8. The wireless communication method of claim 5 , wherein

for performing concurrent transmission with respect to the signal transmitted by the third wireless station, the first wireless station extracts packet length information from the signal transmitted by the third wireless station, and adjusts a length of a packet to transmit based on the extracted packet length information such that transmission of the packet to transmit completes substantially at the same time as transmission of the packet transmitted by the third wireless station.