Relay apparatus, communication apparatus, communication system, and relay method

A communication apparatus, comprising:

• a wireless station receiver that receives a unicast frame converted from a multicast frame;
• a relay apparatus;
• a wireless station notifier that notifies the relay apparatus, which is capable of converting a multicast frame to a unicast frame, of functional information used to identify the presence of a function of transferring the received unicast frame to an application installed in the communication apparatus to utilize the received unicast frame;
• the relay apparatus for forwarding a received multicast frame to a communication apparatus at a specified communication rate, comprising:
• an access point determiner that determines whether or not the communication apparatus can utilize a unicast frame that is converted from the received multicast frame based on a specified condition that includes a transmission available condition, and wherein the access point determiner estimates a duration required for the transmission of the converted unicast frame and determines whether or not the estimated duration is within an available range for transmission by the relay apparatus;
• an access point prohibiter that prohibits a conversion of the multicast frame to the unicast frame when the access point determiner negates the availability;
• and
• an access point unicast forwarder that executes the conversion, that sets a relatively higher communication rate than the specified communication rate, and that forwards the converted unicast frame to the communication apparatus at the relatively higher communication rate;
• wherein the access point determiner includes:
• an access point acquirer that obtains information which represents the presence of a function of receiving the converted unicast frame from the communication apparatus, and transferring the received unicast frame to the application;
• and
• the specified condition includes a functional condition that the communication apparatus has the specific function.

A communication system including a communication apparatus and a relay apparatus that forwards a received multicast frame to the communication apparatus at a specified communication rate,

• the communication apparatus comprising:
• a wireless station notifier that notifies the relay apparatus of functional information used to identify the presence or absence of a function of receiving a unicast frame converted from a multicast frame and transferring the received unicast frame to an application, and the relay apparatus comprising:
• an access point determiner that obtains the functional information notified by the communication apparatus and that determines an availability of the converted and forwarded unicast frame by the application, based on a specified condition including the functional information and wherein the access point determiner estimates a duration required for the transmission of the converted unicast frame and determines whether or not the estimated duration is within an available range for transmission by the relay apparatus;
• an access point prohibiter that prohibits a conversion from the received multicast frame to the unicast frame when the access point determiner negates the availability;
• and
• an access point unicast forwarder that executes the conversion, that sets a relatively higher communication rate than the specified communication rate, and that forwards the converted unicast frame to the communication apparatus at the relatively higher communication rate;
• wherein the access point determiner includes:
• an access point acquirer that obtains information which represents the presence of a function of receiving the converted unicast frame from the communication apparatus, and transferring the received unicast frame to the application;
• and
• the specified condition includes a functional condition that the communication apparatus has the specific function.

A relay method of relaying a multicast frame received by a relay apparatus, wherein the relay apparatus forwards the received multicast frame to a communication apparatus at a specified communication rate, the relay method comprising the steps of:

• receiving from the communication apparatus, functional information used to identify the presence of a function of receiving a unicast frame converted from the multicast frame and transferring the received unicast frame to an application installed in the communication apparatus;
• determining whether or not the communication apparatus can utilize a unicast frame that is converted from the received multicast frame, based on the functional information notified by the communication apparatus, estimating a duration required for the transmission of the converted unicast frame, and determining whether or not the estimated duration is within an available range for transmission by the relay apparatus;
• converting the received multicast frame to the unicast frame when the determiner affirms the availability, setting a communication rate relatively higher than the specified communication rate, and forwarding the converted unicast frame to the communication apparatus at the relatively higher rate;
• and
• forwarding the received multicast frame to the communication apparatus at the specified communication rate without converting to the unicast frame when the determiner negates the availability;
• wherein the determining includes:
• obtaining information which represents the presence of a function of receiving the converted unicast frame from the communication apparatus, and transferring the received unicast frame to the application;
• and
• the specified condition includes a functional condition that the communication apparatus has the specific function.