Communication apparatus, communication method, and non-transitory computer-readable storage medium
A communication apparatus of a wireless LAN complying with the IEEE802.11 standard series determines, by executing CCA, whether a signal can be transmitted in a frequency channel to be used, transmits RTS in response to determination that the signal can be transmitted in the frequency channel, transmits data to a partner apparatus in a case where CTS is received from the partner apparatus in response to the RTS, and controls to use, in a case where the RTS is transmitted during a predetermined period after the communication apparatus shifts from a first state in which a signal cannot be received to a second state in which a signal can be received in the frequency channel, second transmission power lower than first transmission power used in a case where the RTS is transmitted during a period different from the predetermined period.
1. A communication apparatus of a wireless LAN complying with the IEEE802.11 standard series, comprising:
one or more processors; and
one or more memories that store a program for causing, when executed by the one or more processors, the communication apparatus to:
determine, by executing Clear Channel Assessment (CCA) for determining whether a signal from another communication apparatus is detected at a power level not lower than a predetermined threshold in a frequency channel to be used, whether a signal can be transmitted in the frequency channel;
transmit a Request To Send (RTS) packet in response to determination that the signal can be transmitted in the frequency channel;
transmit data to a communication partner apparatus in a case where a Clear To Send (CTS) packet is received from the communication partner apparatus in response to the RTS packet; and
control to use, in a case where the RTS packet is transmitted during a pre determined period after the communication apparatus shifts from a first state in which a signal cannot be received in the frequency channel to a second state in which a signal can be received in the frequency channel, second transmission power lower than first transmission power used in a case where the RTS packet is transmitted during a period different from the predetermined period,
wherein the communication apparatus can establish a plurality of links, and is configured not to perform reception in a second link different from a first link among the plurality of links while performing transmission in the first link among the plurality of links, and
the communication apparatus is configured to operate in the first state in the second link while performing transmission in the first link, and shift to the second state in the second link in a case where the transmission in the first link is complete.
2. A communication method executed by a communication apparatus of a wireless LAN complying with the IEEE802.11 standard series, comprising:
determining, by executing Clear Channel Assessment (CCA) for determining whether a signal from another communication apparatus is detected at a power level not lower than a predetermined threshold in a frequency channel to be used, whether a signal can be transmitted in the frequency channel;
transmitting a Request To Send (RTS) packet in response to determination that the signal can be transmitted in the frequency channel;
transmitting data to a communication partner apparatus in a case where a Clear To Send (CTS) packet is received from the communication partner apparatus in response to the RTS packet; and
controlling to use, in a case where the RTS packet is transmitted during a predetermined period after the communication apparatus shifts from a first state in which a signal cannot be received in the frequency channel to a second state in which a signal can be received in the frequency channel, second transmission power lower than first transmission power used in a case where the RTS packet is transmitted during a period different from the predetermined period,
wherein the communication apparatus can establish a plurality of links, and is configured not to perform reception in a second link different from a first link among the plurality of links while performing transmission in the first link among the plurality of links, and
the communication method further comprises operating in the first state in the second link while performing transmission in the first link, and shifting to the second state in the second link in a case where the transmission in the first link is complete.
3. The method according to claim 2 , wherein
in the controlling, the predetermined threshold of the CCA used by the communication apparatus during the predetermined period is controlled to be lower than the predetermined threshold of the CCA used during the period different from the predetermined period.
4. The method according to claim 2 , wherein
the communication apparatus can operate in a power-saving mode,
the first state is a Doze state in the power-saving mode, and
the communication method comprises shifting to the second state in a case where the communication apparatus exists from the Doze state.
5. The method according to claim 2 , wherein
the communication apparatus can change the frequency channel to be used,
the first state is a state before the frequency channel to be used is changed, and
the communication method comprises shifting to the second state in a case where the frequency channel to be used is changed.
6. The method according to claim 2 , wherein
the second transmission power is determined based on received signal strength of the signal received from the communication partner apparatus and a target value of reception power of the RTS packet in the communication partner apparatus.
7. The method according to claim 6 , wherein
the second transmission power is determined based further on transmission power of a signal in the communication partner apparatus.
8. The method according to claim 6 , wherein
the target value is a value designated from the communication partner apparatus.
9. The method according to claim 6 , wherein
the target value is a value specified based on a transmission rate of the RTS packet.
10. The method according to claim 2 , wherein
the predetermined period is a NAVSyncDelay time period.
11. The method according to claim 2 , wherein
the first transmission power is maximum transmission power.
12. The method according to claim 2 , wherein
in a case where the CTS packet is not received from the communication partner apparatus and it is determined that a signal can be transmitted in the frequency channel after standing by for the predetermined period, data is transmitted to the communication partner apparatus.
13. A non-transitory computer-readable storage medium that stores a program for causing a communication apparatus of a wireless LAN complying with the IEEE802.11 standard series to:
determine, by executing Clear Channel Assessment (CCA) for determining whether a signal from another communication apparatus is detected at a power level not lower than a predetermined threshold in a frequency channel to be used, whether a signal can be transmitted in the frequency channel;
transmit a Request To Send (RTS) packet in response to determination that the signal can be transmitted in the frequency channel;
transmit data to a communication partner apparatus in a case where a Clear To Send (CTS) packet is received from the communication partner apparatus in response to the RTS packet; and
control to use, in a case where the RTS packet is transmitted during a predetermined period after the communication apparatus shifts from a first state in which a signal cannot be received in the frequency channel to a second state in which a signal can be received in the frequency channel, second transmission power lower than first transmission power used in a case where the RTS packet is transmitted during a period different from the predetermined period,
wherein the communication apparatus can establish a plurality of links, and is configured not to perform reception in a second link different from a first link among the plurality of links while performing transmission in the first link among the plurality of links, and
the communication apparatus is configured to operate in the first state in the second link while performing transmission in the first link, and shift to the second state in the second link in a case where the transmission in the first link is complete.