초록 ▼

A complete collision avoidance contention resolution protocol is provided for networks with stations communicating over a shared access communication medium. The protocol is used where a physical layer connected to the communication medium uses a carrier modulation scheme with multiple frequencies.

A complete collision avoidance contention resolution protocol is provided for networks with stations communicating over a shared access communication medium. The protocol is used where a physical layer connected to the communication medium uses a carrier modulation scheme with multiple frequencies. Stations on the network that desire access to the communication medium use a carrier modulation scheme with multiple frequencies. Stations that desire access simultaneously transmit a single frequency selected at random from a set of physical layer frequencies during an open-contention-interval. At the same time, the stations listen to a combined frequency signal and analyzes it for frequency content. If one station whose own frequency matches the highest frequency signal in the combined signal, the station gains access to a communication medium. If more than one station have the same highest frequency signal in the combined signal, no station gains access to the medium. The stations with the highest frequency signal initiate a restricted-contention-interval. The probability of successful contention resolution increases very rapidly using the restricted-contention-interval. When only one station has the highest frequency signal, it gains access to the medium. By resolving contention prior to providing access to any station, collisions of data are completely eliminated. By partitioning the set of frequencies in contiguous ranges, multiple priority classes can be used with the contention resolution method.

대표청구항 ▼

[ We claim:] [1.] A system for resolving contention for access to a shared communication medium in a computer network of a plurality of stations, the system comprising, in combination:a contention signal transmitter in a first and second station for broadcasting an intent-to-transmit signal of a fre

[ We claim:] [1.] A system for resolving contention for access to a shared communication medium in a computer network of a plurality of stations, the system comprising, in combination:a contention signal transmitter in a first and second station for broadcasting an intent-to-transmit signal of a frequency, the intent-to-transmit signal from said first and second stations combining in the communications medium to create a combined contention signal;a contention signal analyzer for decoding the combined contention signal, the contention signal analyzer operative to compare the frequencies of the intent-to-transmit signals and to determine whether one of the stations broadcast the intent-to-transmit signal with an endmost frequency; anda medium access controller in at least one station to enable the station with the only endmost frequency intent-to-transmit signal to transmit data on the communications medium, and to initiate a restricted contention for access between the stations having intent-to-transmit signals with the same endmost frequency whereby, access to the communication medium is resolved without a collision of data between any two stations.