Feature negotiation protocol and dynamically adjustable retraining sequence for a high speed half duplex modem
First Claim
1. In half-duplex communications between a first modem and a second modem, a method of operating said first modem, comprising the steps of:
- establishing communications with said second modem;
negotiating with said second modem to select a table of retraining sequence durations, each retraining sequence duration of said retraining sequence durations being for a predetermined range of values for a period of non-transmission, said table being one of a plurality of tables contained in a memory;
obtaining a measurement of each said period of non-transmission;
obtaining from said table which was selected a value for said retraining sequence duration corresponding to said measurement;
providing to said second modem a retraining sequence for said retraining sequence duration; and
transmitting data to said second modem.
6 Assignments
0 Petitions
Accused Products
Abstract
A feature negotiation protocol for synchronous operation and a dynamically adjustable retraining sequence. An originating modem, after completing conventional or standard handshaking sequences, sends a list of desired features to an answering modem. The answering modem either concurs with the desired features, if they are all supported, or sends, back to the originating modem, a list of those features which are supported by the answering modem. After the end of a negotiation time-out period, both modems begin operation using the features which are common to both modems or by using default (standard) features for operation. If the adjustable duration retraining sequence is selected then each modem will measure the elapsed time since the end of its last transmission and, at the beginning of its next transmission, send a retraining sequence which is dependent upon this elapsed time. Likewise, each modem will measure the amount of elapsed time since the end of its last reception and expect to receive a retraining sequence which is dependent upon this elapsed time. The adjustable duration retraining sequence generally operates to reduce the total retraining sequence and thereby increases the data throughput rate. The result is a modem which has enhanced feature negotiation capabilities and also a higher data throughput rate.
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Citations
43 Claims
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1. In half-duplex communications between a first modem and a second modem, a method of operating said first modem, comprising the steps of:
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establishing communications with said second modem; negotiating with said second modem to select a table of retraining sequence durations, each retraining sequence duration of said retraining sequence durations being for a predetermined range of values for a period of non-transmission, said table being one of a plurality of tables contained in a memory; obtaining a measurement of each said period of non-transmission; obtaining from said table which was selected a value for said retraining sequence duration corresponding to said measurement; providing to said second modem a retraining sequence for said retraining sequence duration; and transmitting data to said second modem. - View Dependent Claims (2, 3, 4, 5, 6)
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7. In half-duplex communications between a first modem and a second modem, a method of operating said second modem, comprising the steps of:
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establishing communications with said first modem; negotiating with said first modem to select a table of retraining sequence durations, each retraining sequence duration of said retraining sequence durations being for a predetermined range of values for a period of non-reception, said table being one of a plurality of tables contained in a memory; obtaining a measurement of each said period of non-reception; obtaining from said table which was selected a value for said retraining sequence duration corresponding to said measurement; entering a resynchronization mode; using a signal from said first modem for said retraining sequence duration to effect resynchronization after said period of non-reception; and entering a data transfer mode. - View Dependent Claims (8)
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9. In half-duplex communications between a first modem and a second modem, a method of operating said modems to improve resynchronization of a receiver in said second modem to a transmitter in said first modem after a period during which said transmitter of said first modem has not sent a signal to said receiver of said second modem, comprising:
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a first modem procedure comprising the steps of; obtaining a first measurement of said period; determining a first duration dependent upon said first measurement; providing to said second modem a retraining sequence for said first duration; and sending data to said second modem; and a second modem procedure comprising the steps of; obtaining a second measurement of said period; determining a second duration dependent upon said second measurement, said second duration being less than said first duration when said second measurement is not greater than said first measurement; operating in a resynchronization mode for said second duration and using said retraining sequence from said first modem to effect said resynchronization; and operating in an online mode. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. An improved half-duplex modem, comprising:
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a modem transmitter comprising; first means for measuring a first elapsed time since a preceding signal transmission; second means responsive to said first elapsed time for determining a transmitted retraining sequence duration; and third means responsive to said retraining sequence duration for generating a retraining sequence; and a modem receiver comprising; fourth means for measuring a second elapsed time since a preceding signal reception; fifth means responsive to said second elapsed time for determining a received retraining sequence duration, said received retraining sequence duration being less than said transmitted retraining sequence duration when said second elapsed time is not greater than said first elapsed time; and sixth means for effecting resynchronization of said receiver during said received retraining sequence duration by using a received retraining sequence. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. In half-duplex communications between a first modem and a second modem, a method of operating said modems, comprising:
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a first modem procedure comprising the steps of; establishing communications with said second modem; negotiating with said second modem to select a table of transmitted retraining sequence duration values, each of said transmitted retraining sequence duration values being for a predetermined range of values for a first elapsed time, said table being one of a plurality of tables contained in a memory; obtaining a value for said first elapsed time, said first elapsed time being measured from termination of a preceding transmission; obtaining from said table which was selected a value for said transmitted retraining sequence duration corresponding to said value for said first elapsed time; transmitting a retraining sequence for said transmitted retraining sequence duration; and transmitting data to said second modem; and a second modem procedure comprising the steps of; establishing communications with said first modem; negotiating with said first modem to select a table of received retraining sequence duration values, each of said received retraining sequence duration values being for a predetermined range of values for a second elapsed time, said table being one of a plurality of tables contained in said memory; obtaining a value for said second elapsed time, said second elapsed time being measured from termination of a preceding reception; obtaining from said table which was selected a value for said received retraining sequence duration corresponding to said value for said second elapsed time; entering a resynchronization mode; retraining circuits in said second modem for a period at least equal to said value for said received retraining sequence duration; and entering a data transfer mode. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43)
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Specification