Patent US1938992A successfully refreshed from Google Patents.
Patent EP0140077A2 successfully refreshed from Google Patents.
EP0140077A2
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EP
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Method for controlling access to the communications medium in a carrier sense multiple access system with collision avoidance
Assignee: International Business Machines Corp
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Filing: 1984-09-10
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Granted: —
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Expires: 2004-09-10
Abstract
Abstract A network arbitration period following the termination of each transmitted frame is divided into a plurality of access windows which are assigned to respective stations in the network. Any station desiring to gain access to the network can acquire the network by transmitting during its assigned access window if no station assigned an earlier access window has already begun transmitting. The access window assignments can be rotated to equitably distribute access to the network.
Inventors
- 👤 Philip Erna Milling
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 18:23
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/40143; H04L12/40156; H04L12/407
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
108 words
A method for enabling multiple terminals to distributively control their access to a shared communications medium in a carrier sense multiple access mode, with low probability of collision, characterized in that it comprises the steps of : reserving a predetermined period of time, following each transition of the medium from busy to idle status, for access arbitration by the terminals then ready to originate communications to the medium; assigning unique access time windows within said predetermined period to all of the terminals using said medium; and granting access to said medium within any arbitration period to the terminal then ready to communicate and having the earliest access window.
Claim 2
Independent Claim
108 words
A method for enabling multiple terminals to distributively control their access to a shared communications medium in a carrier sense multiple access mode, with low probability of collision, characterized in that it comprises the steps of : reserving a predetermined period of time, following each transition of the medium from busy to idle status, for access arbitration by the terminals then ready to originate communications to the medium; assigning unique access time windows within said predetermined period to all of the terminals using said medium; and granting access to said medium within any arbitration period to the terminal then ready to communicate and having the earliest access window.
Claim 3
Dependent Claim
31 words
A method for controlling access in accordance with claim 1 characterized in that it further comprises the step of varying said window assignments after any terminal gains access to said medium.
Claim 4
Dependent Claim
81 words
The method of claim 2 characterized in that it further comprises the steps of : assigning unique arbitration addresses to the terminals sharing said medium; requiring each terminal gaining access to the medium to generate an access control number and transmit that number to the medium as part of its communication; and requiring all terminals contending for access to use the sum of that number and their respective assigned addresses to define their respective access windows in the next arbitration period.
Claim 5
Dependent Claim
54 words
The method of claim 3 characterized in that the terminals use a predetermined control number to arbitrate their initial access, and in that each terminal thereafter gaining access to the medium generates a new control number by adding an incremental value to the value of the control number from which it derived its access.
Claim 6
Dependent Claim
19 words
The method of claim 4 characterized in that the incremental value added by each terminal is a predetermined constant.
Claim 7
Dependent Claim
19 words
The method of claim 4 characterized in that the incremental value is a variable derived by random number generation.
Claim 8
Dependent Claim
68 words
The method of claim 3 characterized in that said assigned addresses are established by : assigning node addresses to terminals in a numerical sequence; and developing arbitration addresses from said node addresses by reversing the order of bits in the node addresses; whereby the times allotted to access windows within each arbitration periods are spread out in accordance with the number of terminals then actually using the medium.
Claim 9
Dependent Claim
49 words
The method of claim 3, characterized in that at least some of the transmissions are from a transmitting station to a destination station, said stations maintaining the same access window assignments in the next arbitration period if a transmitting station does not receive a response from a receiving station.
Claim 10
Dependent Claim
46 words
The method of claim 3, characterized in that the access control number received with a transmission is checked for validity at each station, and a station uses the old control number if the access control number received with the last transmission is determined to be invalid.
Claim 11
Dependent Claim
17 words
The method of claim 5, characterized in that said predetermined constant is a value greater than 1.
Claim 12
Independent Claim
161 words
A method of controlling access by each station to the communications medium, in a communications system wherein a plurality of stations each transmit at different times to one another over a shared communications medium, each said station including detection means for detecting the presence or absence of a transmission on said communications medium, said method being characterized in that it comprises : reserving an arbitration period of time commencing from the termination of each transmission on said medium; dividing said arbitration period into a plurality of access windows; assigning different ones of said access windows to different ones of said plurality of stations, with each station being permitted to begin transmitting only at its assigned access window; detecting at each station the termination of a transmission transmitted over said medium; and transmitting, from any station desiring access to said medium, during its respective access window if no other station has transmitted during a previous access window in the same arbitration period.
Claim 13
Independent Claim
161 words
A method of controlling access by each station to the communications medium, in a communications system wherein a plurality of stations each transmit at different times to one another over a shared communications medium, each said station including detection means for detecting the presence or absence of a transmission on said communications medium, said method being characterized in that it comprises : reserving an arbitration period of time commencing from the termination of each transmission on said medium; dividing said arbitration period into a plurality of access windows; assigning different ones of said access windows to different ones of said plurality of stations, with each station being permitted to begin transmitting only at its assigned access window; detecting at each station the termination of a transmission transmitted over said medium; and transmitting, from any station desiring access to said medium, during its respective access window if no other station has transmitted during a previous access window in the same arbitration period.
References Cited (Backward Citations)
No citation records indexed.
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