A-point to multi-points communication system

An a-point to multi-points communication system comprising:

• a master station for transmitting an a-point to multi-points frame;
• and
• a plurality of slave stations for receiving said a-point to multi-points frame, and for returning response frame each including an indicator for indicating to said master station, whether said a-point to multi-points frame from said master station is received normally or abnormally by a slave station in response to said a-point to multi-points frame;
• said master station including
• counting means for counting the number of slave stations which returns a response frame including an indicator indicating normal receiving of said a-point to multi-points frame, and
• a detecting means for detecting whether the number of slave stations counted by said counting means is below a predetermined value indicating that said a-point to multi-points frame is to be retransmitted after a time delay, in response to said a-point to multi-points frame.

An a-point to multi-points communication system comprising:

• a master station for transmitting an a-point to multi-points frame;
• and
• a plurality of slave stations for receiving said a-point to multi-points frame, and for returning response frames each including an indicator for requesting, from said master station, retransmission of said a-point to multi-point frame in case where said a-point to multi-points frame is not received by a slave station, in response to said a-point to multi-points frame;
• said master station including
• counting means for counting the number of slave stations which return response frame including an indicator requesting retransmission of said a-point to multi-points frame, and
• a detection means for detecting whether the number of slave stations counted by said counting means is above a predetermined value indicating a request for retransmitting said a-point to multi-point frame.

An a-point to multi-points communication system comprising:

• a master station for transmitting an a-point to multi-point frame;
• and
• a plurality of slave stations for receiving said a-point to multi-points frame and for returning response frames each including an indicator for indicating, to said master station, whether said a-point to multi-points frame from said master station is received normally or abnormally by said slave station in response to said received a-point to multi-points frame;
• said master station including:
• counting means for counting the number of slave stations which return frame including an indicator indicating abnormal receiving or normal receiving of said a-point to multi-points frame, and
• a detecting means for detecting whether the number of slave stations counted by said counting means is above a predetermined value indicating that said a-point to multi-points frame is to be retransmitted after a time delay, in response to said a-point to multi-points frame.

An a-point to multi-points communication system comprising:

• a master station for transmitting an a-point to multi-points frame which includes a sequence number;
• and
• a plurality of slave stations for receiving said a-point to multi-points frame to said master station and for returning response frames each including an indicator for indicating whether said a-point to multi-points frame from said master station is received normally or abnormally by a salve station in response to said received a-point to multi-points frame;
• each of said slave stations comprises
• memory means for storing an indicator for indicating whether said a-point to multi-points frame from said master station is received normally or abnormally corresponding to said sequence number and for generating said response frame with said indicator, and
• returning means for returning a response frame including an indicator in response to said received a-point to multi-points frame.

An a-point to multi-points communication system comprising:

• a master station for transmitting an a-point to multi-points frame;
• and
• a plurality of slave stations for receiving said a-point to multi-points frame from said master station and for returning response frames to said master station, in response to said a-point to multi-points frame received from said master station;
• said master station comprises
• obtaining means for obtaining a receiving status of said a-point to multi-points frame included in said response frames from said slave stations,
• classifying means for classifying said receiving status,
• selection means for selecting a control content from a retransmission of said a-point to multi-points frame, a transmission of a next a-point to multi-points frame, and a suspension of transmitting, responsive to said classified receiving status.

In an a-point to multi-points communication system including a master station for transmitting an a-point to multi-points frame and a plurality of slave stations for receiving said a-point to multi-points frame and returning response frames each including an indicator for indicating to said master station whether said a-point to multi-points frame from said master station is received normally or abnormally by a slave station in response to said received a-point to multi-points frame, said master station comprising:

• counting means for counting the number of slave stations which return a response frame including an indicator indicating abnormal receiving of said a-point to multi-points frame;
• detecting means for detecting whether the number counted by said counting means is above a predetermined value;
• and
• retransmission means for retransmitting said a-point to multi-points frame if said detecting means detects that the number counted by said counting means is above said predetermined value.

A retransmitting method for controlling a master station in an a-point to multi-points communication system including said master station for transmitting an a-point to multi-points frame and a plurality of slave stations for receiving said a-point to multi-points frame and returning response frames each including an indicator for indicating, to said master station, whether said a-point to multi-points frame from said master station is received normally or abnormally by a slave station in response to said received aa-point to multi-points frame, said retransmitting method comprising of:

• counting the number of slave stations which returns a response frame including an indicator which indicates abnormal receiving of said a-point to multi-points frame;
• detecting whether the number counted in the counting step is above a predetermined value;
• and
• retransmitting said a-point to multi-points frame if said detecting means detects that the number counted in the counting step is above said predetermined value.

A method for communication in an a-point to multi-points communication system, said method comprising steps of:

• transmitting information from a master station;
• receiving said information at a plurality of slave stations;
• returning response frames, each including an indicator for indicating to said master station whether said information from said master station is received normally or abnormally at said slave stations in response to said received information;
• counting the number of slave stations which returns a response frame including an indicator which indicates abnormal receiving of said a-point to multi-points frame at said master station;
• detecting whether the number counted in the counting step is above a predetermined value at said master station;
• and
• retransmitting said a-point to multi-points frame if said detecting means detects that the number counted in the counting step is above said predetermined value at said master station.