Data communication system and method for transporting data

A receiving entity for receiving data transmitted from a sending entity over a data communication system wherein the sending entity divides data into a plurality of groups which are sequentially indexed with group numbers, each group is segmented into a plurality of packets which are sequentially indexed in each group with sequence numbers, the receiving entity comprising:

• receiving means for receiving each packet transmitted over the data communication system, each packet having a group number indicating a group and a sequence number;
• an expected sequence counter for storing an expected sequence number for the group, the expected sequence counter being incremented when a received packet is accepted for the group;
• acceptance determining means for accepting a received packet when the sequence number of the received packet matches the expected sequence number of the group, and for discarding the received packet when the sequence number of the received packet does not match the expected sequence number of the group;
• a negative acknowledgment sent indicator which is set when the received packet is discarded and no negative acknowledgment sent indicator has been set for the group, so as to indicate that a negative acknowledgment has been sent and the receiving entity is waiting for a packet with the expected sequence number;
• a last packet detector for detecting a last packet of the group;
• and
• acknowledgment sending means for sending a negative acknowledgment when the sequence number of the received packet is greater than the expected sequence number and the negative acknowledgment sent indicator has not been set, and sending a positive acknowledgment when the received packet is the last packet of the group and the sequence number of the received packet matches or smaller than the expected sequence number.

A method for transporting data between a sending entity and a receiving entity over a data communication system, the method comprising the steps of:

• the sending entity dividing data into a plurality of groups which are sequentially indexed with group numbers, each group being segmented into a plurality of packets which are sequentially indexed in each group with sequence numbers;
• the sending entity sequentially transmitting the packets of each group to the receiving entity;
• the receiving entity receiving each packet transmitted;
• the receiving entity reading a group number identifying a group and a sequence number of the received packet, and comparing the sequence number with an expected sequence number of the group;
• when the sequence number of the received packet matches the expected sequence number,
• accepting the received packet;
• incrementing the expected sequence number of the group;
• determining whether the received packet is a last packet of the group;
• when the received packet is the last packet, sending a positive acknowledgment to the sending entity;
• and
• when the received packet is not the last packet, returning to the step of receiving each packet;
• when the sequence number of the received packet does not match the expected sequence number,
• discarding the received packet;
• determining whether a negative acknowledgment sent indicator has been set;
• when the negative acknowledgment sent indicator has not been set,
• sending a negative acknowledgment to the sending entity;
• and
• setting the negative acknowledgment sent indicator;
• and
• when the negative acknowledgment sent indicator has been set,
• returning to the step of receiving each packet.

A data communication system for transporting data between a sending entity and a receiving entity, the data communication system comprising:

• in the sending entity:
• dividing means for dividing data into a plurality of groups which are sequentially indexed with group numbers, each group being segmented into a plurality of packets which are sequentially indexed in each group with sequence numbers;
• packet sending means for sequentially transmitting the packets of each group to the receiving entity;
• in the receiving entity:
• receiving means for receiving each packet transmitted over the data communication system, each packet having a group number identifying a group and a sequence number;
• an expected sequence counter for storing an expected sequence number for the group, the expected sequence counter being incremented when a received packet is accepted for the group;
• acceptance determining means for accepting a received packet when the sequence number of the received packet matches the expected sequence number of the group, and for discarding the received packet when the sequence number of the received packet does not match the expected sequence number of the group;
• a negative acknowledgment sent indicator which is set when the received packet is discarded and no negative acknowledgment sent indicator has been set for the group, so as to indicate that a negative acknowledgment has been sent and the receiving entity is waiting for a packet with the expected sequence number;
• a last packet detector for detecting a last packet of the group;
• and
• acknowledgment sending means for sending a negative acknowledgment when the sequence number of the received packet is greater than the expected sequence number and the negative acknowledgment sent indicator has not been set, and sending a positive acknowledgment when the received packet is the last packet of the group and the sequence number of the received packet matches or smaller than the expected sequence number.

A method for transporting data between a sending entity and a receiving entity over a data communication system, the method comprising the steps of:

• the sending entity dividing data into a plurality of groups which are sequentially indexed with group numbers, each group being segmented into a plurality of packets which are sequentially indexed in each group with sequence numbers;
• the sending entity marking a last packet of each group with a last packet indicator.
• the sending entity sequentially transmitting the packets of each group to the receiving entity;
• the receiving entity receiving each packet transmitted;
• the receiving entity reading a group number identifying a group and a sequence number of the received packet, and comparing the sequence number with an expected sequence number of the group;
• the receiving entity accepting the received packet for further processing when the sequence number of the received packet matches the expected-sequence number;
• the receiving entity incrementing the expected sequence number of the group when the received packet is accepted;
• the receiving entity discarding the received packet when the sequence number of the received packet does not match the expected sequence number;
• the receiving entity setting a negative acknowledgment sent indicator when the packet is discarded and no negative acknowledgment sent indicator has been set for the group, the negative acknowledgment sent indicator indicating that a negative acknowledgment has been sent and the receiving entity is waiting for a packet with the expected sequence number;
• the receiving entity sending a negative acknowledgment indicating the group number and the expected sequence number when the sequence number of the received packet is greater than the expected sequence number and the negative acknowledgment sent indicator has not been set;
• the sending entity re-transmitting to the receiving entity, when the negative acknowledgment is received, the packet having the group number and the expected sequence number indicated in the negative acknowledgment and packets having subsequent sequence numbers of the group;
• the receiving entity detecting a last packet of the group by detecting the last packet indicator;
• the sending entity starting a timer of a predetermined length when the last packet of the group is sent;
• the receiving entity sending a positive acknowledgment indicating the group number when the received packet is the last packet of the group and the sequence number of the. received packet matches or smaller than the expected sequence number;
• the sending entity re-transmitting all packets of the group to the receiving entity when the timer expires before receipt of the positive acknowledgment;
• the sending entity stopping the timer when the positive acknowledgment is received;
• the sending entity storing the group number indicated in the positive acknowledgment and the sequence number of the last packet of the group;
• and
• the sending entity numbering packets in a different group having the group number starting from the sequence number of the last packet plus one.

A data communication system for transporting data between a sending entity and a receiving entity, the data communication system comprising:

• in the sending entity:
• dividing means for dividing data into a plurality of groups which are sequentially indexed with group numbers, each group is segmented into a plurality of packets which are sequentially indexed in each group with sequence numbers;
• means for marking a last packet of each group with a last packet indicator;
• packet sending means for sequentially transmitting the packets of each group to the receiving entity;
• a timer of a predetermined length;
• timer setting means for starting the timer when the last packet of the group is transmitted, and stopping the timer when a positive acknowledgment or a negative acknowledgment is received;
• in the receiving entity:
• receiving means for receiving each packet transmitted over the data communication system, each packet having a group number identifying a group and a sequence number;
• an expected sequence counter for storing an expected sequence number for the group, the expected sequence counter being incremented when a received packet is accepted for the group;
• acceptance determining means for accepting the received packet when the sequence number of the received packet matches the expected sequence number of the group, and for discarding the received packet when the sequence number of the received packet does not match the expected sequence number of the group;
• a negative acknowledgment sent indicator which is set when the received packet is discarded and no negative acknowledgment sent indicator has been set for the group, so as to indicate that a negative acknowledgment has been sent and the receiving entity is waiting for a packet with the expected sequence number;
• resetting means for resetting the negative acknowledgment sent indicator when a packet having the expected sequence number of the group is received;
• a last packet detector for detecting the last packet of the group having the last packet indicator;
• acknowledgment sending means for sending a negative acknowledgment when the sequence number of the received packet is greater than the expected sequence number and the negative acknowledgment sent indicator has not been set, and sending a positive acknowledgment when the received packet is the last packet of the group and the sequence number of the received packet matches or smaller than the expected sequence number;
• indicating means for indicating the group number and the expected sequence number in the negative acknowledgment and the positive acknowledgment;
• wherein the packet sending means of the sending entity re-transmits to the receiving entity the packet having the group number and the expected sequence number indicated in the negative acknowledgment and packets having subsequent sequence numbers of the group when the negative acknowledgment is received, and retransmits all packets of the group when the timer expires before the positive acknowledgment is received.