Data modem with adaptive synchronized speed change
First Claim
1. In a data communication system including a first modem and a second modem coupled together through a transmission channel, said transmission channel including a first path for transmission from said first modem to said second modem and a second path for transmission from said second mdem to said first modem, a method for coordinating a change in the transmission rates of said first and second modems, the method comprising the ordered steps of:
- attempting to train and retrain said modems;
determining, at said first modem, that said second path of said transmission channel is adequately high in quality to support an increase in transmission rate;
transmitting a request to increase speed from said first modem to said second modem;
determining, at said second modem, that said first path of said transmission channel is adequately high in quality to support an increase in transmission rate wherein the step of determining includes mapping a duration of time wherein said signal quality is deemed to be poor into a count, accumulating said count to produce an accumulated count and comparing said accumulated count to a predetermined maximum count for a predetermined time line so that upspeed decisions can occur with a moderate amount of transient impairment; and
wherein said mapping step includes assigning integer values to time periods of poor signal quality such that larger integers are assigned to longer periods of poor signal quality and smaller integers are assigned to shorter periods of poor signal quality, and the count is totaled for said time limit;
acknowledging said request to increase speed from said first modem by transmitting an acknowledgment signal from said second modem to said first modem;
squelching transmission at said first modem;
transmitting a training sequence at said increased speed from said second modem to said first modem; and
transmitting a traning sequence at said increased speed from said first modem to said second modem.
6 Assignments
0 Petitions
Accused Products
Abstract
A method for changing the data transmission rates in a synchronous data communication system including a first modem and a second modem coupled together through a transmission channel, the transmission channel including a first path for transmissions from the first modem to the second modem and a second path for transmission from the second modem to the first modem, includes the steps of determining, at the first modem, that the second path of the transmission channel is adequately high in quality to support an increase in transmission rate. Next it is determined, at the second modem, that the first path of the transmission channel is adequately high in quality to support an increase in transmission rate. A training sequence is then transmitted at an increased transmission rate from the second modem to the first modem. Next, a training sequence is transmitted at the increased transmission rate from the first modem to the second modem.
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Citations
16 Claims
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1. In a data communication system including a first modem and a second modem coupled together through a transmission channel, said transmission channel including a first path for transmission from said first modem to said second modem and a second path for transmission from said second mdem to said first modem, a method for coordinating a change in the transmission rates of said first and second modems, the method comprising the ordered steps of:
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attempting to train and retrain said modems; determining, at said first modem, that said second path of said transmission channel is adequately high in quality to support an increase in transmission rate; transmitting a request to increase speed from said first modem to said second modem; determining, at said second modem, that said first path of said transmission channel is adequately high in quality to support an increase in transmission rate wherein the step of determining includes mapping a duration of time wherein said signal quality is deemed to be poor into a count, accumulating said count to produce an accumulated count and comparing said accumulated count to a predetermined maximum count for a predetermined time line so that upspeed decisions can occur with a moderate amount of transient impairment; and
wherein said mapping step includes assigning integer values to time periods of poor signal quality such that larger integers are assigned to longer periods of poor signal quality and smaller integers are assigned to shorter periods of poor signal quality, and the count is totaled for said time limit;acknowledging said request to increase speed from said first modem by transmitting an acknowledgment signal from said second modem to said first modem; squelching transmission at said first modem; transmitting a training sequence at said increased speed from said second modem to said first modem; and transmitting a traning sequence at said increased speed from said first modem to said second modem. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In a data modem, a circuit arrangement for effecting transmission speed changes between a pair of modems comprising in combination:
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training means for attempting to train and retrain said modem; first means for establishing the quality of transmission line; second means for counting retrain attempts as a measure of line quality; fallback decision means, responsive to said second means, for producing an output representing a demand for reduction in transmission speed whenever a predetermined number of retrain attempts occur within a selected period of time; fallforward decision means, responsive to said first means, for producing an output representing a request for increase in transmission speed whenever the average signal quality is greater than a predetermined threshold; establishing means for establishing said data modem as having an identity designated as either master or slave, including means for determining if said modem is the most recent of said pair of modems to demand a speed reduction, and wherein said modem is designated master in the event it is said most recent requester; transmitting means for transmitting requests for increases and demands for reductions in transmission speed over said transmission line; and inhibiting means for inhibiting said transmitting means from transmitting requests for increases in speed unless said modem'"'"'s identity is that of master. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification