Method and apparatus for exchanging data within a digital communications system
AssigneeHewlett-Packard Company
InventorNicholas McKeown
Life of this patent
Estimating the term…
Abstract
A Communications system having a protocol whereby a plurality of stations (100) are granted access to a network. Each station may send a packet of data in each cycle of operation. At least one station with data to transmit identifies the station that immediately precedes it among stations which are to transmit data (e.g., as indicated in a corresponding reservation slot). On the basis of that identification the one station transmits its data packet promptly after the preceding station has begun transmitting its data packet. At least in same cases the one station initiates its transmission prior to having finished receiving the packet transmitted by the preceding station at a time calculated to avoid data collision.
Claims26
A communications system arranged to operate in cycles, comprising a plurality of stations interconnected by transmission paths, each station being permitted to transmit data during each cycle in a predetermined order of permitted transmissions, each data transmission including identity information indicative of the identity of the transmitting station, at least one of said stations comprising:
- (a) first means for determining whether said at least one station is a first station in a sequence of stations with data to transmit in a given cycle;
- and
- (b) second means for determining when said at least one station is a next station with data to transmit, including means for receiving data transmissions and identifying an originating station, and means for transmitting data in said given cycle at a timing dependent upon the actual reception of transmissions in said given cycle from an immediately preceding station in said order of permitted transmissions, this timing being in advance of when said at least one station has finished receiving data from said immediately preceding station and being judged by said at least one station to avoid its data transmission colliding at any other station with a data transmission from said immediately preceding station.
A method of operating a communications system having a plurality of stations arranged to operate in cycles, comprising the steps of:
- (a) determining an order of permitted transmission of data from said stations, and requiring each data transmission from at least one of said stations to include identity information indicative of the identity of the transmitting station;
- (b) determining a first station in a sequence of stations with data to transmit in a given cycle, and transmitting data from said first station;
- (c) determining a next station with data to transmit, and transmitting data in said given cycle from said next station at a timing depending upon the actual reception of transmissions from an immediately preceding station in said order of permitted transmissions, this timing being in advance of an end of transmission in said given cycle by said immediately preceding station in said sequence of stations and at a time before said next station has finished receiving data from said immediately preceding station, said time judged to avoid the data transmitted by said next station colliding at any other station with data transmitted from said immediately preceding station.
Dependencies are inferred from the claim text.