Communication apparatus, and method and program for controlling same

A method of controlling a communication apparatus for communicating by switching between a first communication period in which contention access control is performed and a second communication period in which non-contention access control is performed, wherein a first frequency bandwidth is used for a respective communication in the first communication period and the second communication period, the method comprising the steps of:

• determining the state of access contention in the first communication period;
• changing a frequency bandwidth used for communication in the second communication period and not changing a frequency bandwidth used for communication in the first communication period in case that the first communication period is shorter than the second communication period and access contention exceeding a predefined threshold has occurred in the first communication period, or changing the frequency band used for the communication of the first communication period and not changing the frequency band used for the communication of the second communication period in case that the first communication period is longer than the second communication period and access contention exceeding a predefined threshold has occurred in the first communication period;
• and
• changing a length of a communication period, which is the first or second communication period and for which the frequency bandwidth has been changed by said first changing unit, from the length of the communication period used prior to changing the frequency bandwidth.

A non-transitory medium encoded with a program for causing a computer, which is incorporated within a communication apparatus for communicating by switching between a first communication period in which contention access control is performed and a second communication period in which non-contention access control is performed, wherein a first frequency bandwidth is used for a respective communication in the first communication period and the second communication period, to function as:

• a determination unit configured to determine the state of access contention in the first communication period;
• a first changing unit configured to change a frequency bandwidth used for communication in the second communication period and not to change a frequency bandwidth used for communication in the first communication period in case that the first communication period is shorter than the second communication period and access contention exceeding a predefined threshold has occurred in the first communication period, or to change the frequency band used for the communication of the first communication period and not to change the frequency band used for the communication of the second communication period in case that the first communication period is longer than the second communication period and access contention exceeding a predefined threshold has occurred in the first communication period;
• and
• a second changing unit configured to change a length of a communication period, which is the first or second communication period and for which the frequency bandwidth has been changed by said first changing unit, from the length of the communication period used prior to changing the frequency bandwidth.