EP0122765A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Network protocol for integrating synchronous and asynchronous traffic on a common serial data bus
Assignee: AT&T Inc
•
Filing: 1984-04-09
•
Granted: —
•
Expires: 2004-04-09
Abstract
Abstract Contention among a plurality of synchronous and asynchronous devices connected to a shared communication medium for access to time slots in a sequence of frames is resolved by assigning a unique priority word including a priority code prefix to each device and granting access to a given slot by comparing the value of the priority words assigned to completing devices. The priority code prefix is assigned as a joint function of whether synchronous or asynchronous communication is desired and whether synchronous communication is being initiated or continued. In each assignment protocol, synchronous communication is enabled by assuring any device that initially gains access to a particular time slot continued access to the same slot in succeeding frames. If desired, devices with synchronous access may relinquish unused time slots to asynchronous traffic, while reserving the ability to resume synchronous communication.
Inventors
- 👤 Anthony Acampora
- 👤 Michael Gene Hluchjy
- 👤 Chan David Tsao
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 19:02
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/407; H04L12/413; H04L12/4135; H04L12/64
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
203 words
A method for enabling one of a plurality of devices contending for access to a shared communication medium to gain access to said medium for asynchronous or synchronous communication, synchronous communication requiring access to at least one particular time slot in each of a sequence of frames each of which includes an integral number of time slots, comprising steps of: a) assigning a unique priority word to each device contending during each attempt to gain access to one of said time slots, and b) granting access to a time slot to one of said contending devices by comparing, most significant bit first, the values of said assigned priority words, CHARACTERIZED IN THAT said priority word assigning step comprises: c) selecting said priority word as a joint function of 1) whether a device is contending for synchronous or asynchronous access, and 2) whether a device contending for synchronous access is initially contending for a time slot or has already accessed a particular time slot. 2. The method defined in claim 1 wherein said assigning step is further characterized by d) forming said priority word by prefixing a binary number uniquely identifying each of said devices with a priority code containing at least one bit.
Claim 2
Dependent Claim
24 words
The method defined in claim 2 CHARACTERIZED IN THAT said assigning step comprises selecting a one bit priority code according to the following table:
Claim 3
Dependent Claim
24 words
The method defined in claim 2 CHARACTERIZED IN THAT said forming step comprises forming a two bit priority code according to the following table:
Claim 4
Dependent Claim
42 words
The method defined in claim 4 CHARACTERIZED IN THAT said assigning step comprises changing said priority code from 11 to 01 when a device which already has access to a particular time slot relinquishes said slot to another device seeking asynchronous access.
Claim 5
Dependent Claim
24 words
The method defined in claim 2 CHARACTERIZED IN THAT said forming step comprises forming a three bit priority code according to the following table:
Claim 6
Dependent Claim
134 words
Apparatus for enabling a plurality of devices capable of synchronous and asynchronous communication to gain access to time slots on a shared communication medium, comprising: 1) means (1003, 1020) for assigning priority information to each device, said information including variable information, 2) means (1004) for granting access to a time slot by evaluating the priority information assigned to devices contending for that slot, CHARACTERIZED IN THAT said means for assigning (1003, 1020) is arranged to 3) form said variable portion as a function of (a) the synchronous or asynchronous nature of the communication desired by the device, and (b) the initial or ongoing status of said synchronous communication, and 4) assign higher priority to ongoing synchronous communication and lower priority to initial synchronous communication, both as compared to the priority assigned to asynchronous communication.
Claim 7
Dependent Claim
134 words
Apparatus for enabling a plurality of devices capable of synchronous and asynchronous communication to gain access to time slots on a shared communication medium, comprising: 1) means (1003, 1020) for assigning priority information to each device, said information including variable information, 2) means (1004) for granting access to a time slot by evaluating the priority information assigned to devices contending for that slot, CHARACTERIZED IN THAT said means for assigning (1003, 1020) is arranged to 3) form said variable portion as a function of (a) the synchronous or asynchronous nature of the communication desired by the device, and (b) the initial or ongoing status of said synchronous communication, and 4) assign higher priority to ongoing synchronous communication and lower priority to initial synchronous communication, both as compared to the priority assigned to asynchronous communication.
Claim 8
Dependent Claim
54 words
The apparatus defined in claim 7 CHARACTERIZED IN THAT said means for assigning priority is arranged to prefix a unique binary number associated with each of said devices with said variable information, and said access granting means is arranged to evaluate said priority information on a bit by bit basis, most significant bit first.
Claim 9
Dependent Claim
29 words
The apparatus defined in claim 8 CHARACTERIZED IN THAT said variable information formed in said priority assigning means includes a two bit code assigned according to the following relationship:
Claim 10
Dependent Claim
52 words
The apparatus defined in claim 9 FURTHER CHARACTERIZED IN THAT said means for assigning is arranged to assign a code "01" during selected time slots accessed by one of said devices engaged in ongoing synchronous communication, whereby said selected time slots can be relinquished to another of said devices for asynchronous communication.
Claim 11
Dependent Claim
63 words
The invention defined in claim 7 CHARACTERIZED IN THAT said variable information further includes a b-bit prefix indicating the periodicity of occurence of unused time slots by a device engaged in ongoing synchronous communication, and the means for granting access is further arranged to compare said b-bit prefix for a device having synchronous access with said b-bit prefix for devices seeking synchronous access.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.