Mapper for high data rate transmission through channels subject to robbed bit signalling
AssigneeGeneral DataComm, Inc.
InventorsYuri Goldstein, Yuri Okunev
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Abstract
A mapper for a PAM encoder is provided and includes apparatus for generating desired code levels, and a constellation matrix memory which stores indications of a plurality of different N-dimensional constellations. The plurality of different constellations are used individually or together to support a plurality of different modem data (bit) rates. In order to maximize performance in the presence of robbed bit signalling, multidimensional constellations having different numbers of points are used together in the coding of a single group of bits.
Claims16
A PAM mapper coupled to telecommunications equipment utilizing robbed bit signalling, said PAM mapper comprising:
- a) a constellation matrix memory means for storing indications of a plurality of different multidimensional PAM constellations having different numbers of constellation points;
- b) means for receiving and storing incoming bits and for grouping the incoming bits into a group of bits based on a transmission data rate and based on a presence of robbed bit signalling;
- and
- c) code generation means coupled to said means for receiving and storing and to said constellation matrix memory means, said code generation means for receiving at least a plurality of said group of bits, for using said plurality of said group of bits to identify N indications of constellation points in at least one selected of said plurality of multidimensional PAM constellations, and for generating N PAM output codes based on said indications, where N is an integer greater than one.
A method for mapping a plurality of incoming bits into PAM code outputs, comprising:
- a) grouping a plurality of said incoming bits into a group of x-y bits based on a desired data rate, and based on a presence of robbed bit signalling, x being a positive integer greater than four;
- b) using at least a plurality of said x-y bits for choosing N indications from a plurality of N-dimensional constellations, N being an integer greater than 1;
- c) utilizing said N indications to choose N PAM code values.
Dependencies are inferred from the claim text.