Control channel for modems
AssigneeConexant Systems, Inc.
InventorsSverrir Olafsson, Sandeep Rajpal
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Abstract
A methodology for a modem control channel is disclosed. The channel allows faster seamless rate change and precoder tap exchange than the baseline procedure for seamless rate change, allowing for more robust transmission of control information. It can also be use to convey side-information in the case of multiple data applications, serving the purpose of mode switching. Thus, with a single control channel both the needs for seamless rate change and transmitting control information for multiple data applications can be met.
Claims17
A method of transmitting control information between a first modem and a second modem operating in accordance with a predetermined ITU V-series modem recommendation without substantially affecting the predetermined modem recommendation in operation, comprising the steps of:
- providing said first modem and said second modem in communication in accordance with the predetermined modem recommendation at a first data rate R1;
- transmitting a data frame from said first modem to said second modem, said data frame comprising a plurality of mapping frames, wherein one of said mapping frames contains a mode indicator (MI) encoded in accordance with an encoding scheme;
- decoding said MI by said second modem in accordance with said encoding scheme;
- proceeding with communication in accordance with said predetermined modem recommendation at a second data rate R2 when said MI indicates control data;
- and
- receiving control information at said second data rate R2 at said second modem.
A method of processing a control indicator in a trellis-coded modulation system with a signal point constellation of "A" points comprising a plurality, "b", of subconstellations, the method comprising the steps of:
- constructing a block code of length "c" such that said block code is capable of producing a plurality, "b.sup.c ", of codewords;
- selecting "d" codewords from said plurality of codewords such that the minimum distance between said "d" codewords is maximized;
- arranging values of said control indicator using said "d" codewords;
- and
- transmitting said control indicator in a plurality, "c", of transmit symbols, where each of said plurality of transmit symbols has the same dimensionality as the signal points contained in said signal point constellation.
Dependencies are inferred from the claim text.