Transmitting sequence numbers of information in a packet data transmission system
First Claim
1. A method of transmitting sequence numbers of information packets in a packet data transmission system, each information packet comprising a control field and an information field, the control field of each information packet including a sequence number of the information packet, comprising the steps of selectively transmitting in said information packet the sequence number of an information packet received in an opposite direction of transmission thereby to acknowledge correct receipt of the received information packet, and transmitting in the control field of each information packet a bit whose state indicates the presence or absence in the information packet of the sequence number of a received information packet being acknowledged.
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Accused Products
Abstract
In a packet data transmission system, correctly received information packets are acknowledged by piggybacking their sequence numbers onto information packets being transmitted. The control field of each information packet includes a bit which indicates whether or not there is a piggybacked acknowledgement. Acknowledgements can also be transmitted separately in control packets having no information field. Each acknowledgement consists of not only the sequence number of a correctly received information packet, but also the acknowledgement status of a plurality of preceding information packets whereby these can be negatively acknowledged if necessary. The sequence numbers can have any one of three different sizes, for efficient transmission of sequence numbers on transmission links of arbitrary transmission speed and length (and hence delay). The sequence number size which is used on any particular transmission link is determined on set-up of the link in dependence upon the transmission speed and the round-trip delay of the link.
194 Citations
37 Claims
- 1. A method of transmitting sequence numbers of information packets in a packet data transmission system, each information packet comprising a control field and an information field, the control field of each information packet including a sequence number of the information packet, comprising the steps of selectively transmitting in said information packet the sequence number of an information packet received in an opposite direction of transmission thereby to acknowledge correct receipt of the received information packet, and transmitting in the control field of each information packet a bit whose state indicates the presence or absence in the information packet of the sequence number of a received information packet being acknowledged.
- 19. A method of transmitting sequence numbers of information packets in a packet data transmission system in which information packets and control packets are transmitted, each packet including a control field including a bit whose state indicates whether the packet is an information packet or a control packet, each information packet including an information field and including a sequence number of the information packet in its control field, the control field of at least some of the control packets including at least one length bit whose state indicates which one of a plurality of different lengths of sequence numbers is used, all of the sequence numbers used having the same length, the method including the step of determining the sequence number length by measuring the round-trip delay D for transmission of a packet via the system and determining said length in dependence upon the measured delay D and the transmission speed T of the system.
- 27. A method of transmitting sequence numbers of information packets in a packet data transmission system, each information packet comprising a control field and an information field, the control field of each information packet including a sequence number of the information packet, comprising the steps of transmitting in the information packets sequence numbers of information packets received in an opposite direction of transmission thereby to acknowledge correct receipt of the received information packets, and transmitting with each sequence number of a received information packet being acknowledged an acknowledgement status of each of n information packets received preceding said received information packet being acknowledged, where n is a positive integer.
Specification