Frame structure for a QAM system
First Claim
1. A method for variable net bit rate digital communications comprising:
- generating a forward error correction (FEC) data frame from one or more interleaved Reed-Solomon (RS) packets, each RS packet encoding a plurality of data bytes;
modulating a plurality of bits of the FEC data frame using a punctured trellis coder that is operated at a selected code rate, the code rate being selected based on white noise performance of a digital communications system;
mapping the modulated bits to quadrature amplitude modulation (QAM) symbols using a QAM constellation selected from a set of candidate QAM constellations; and
providing a transmission frame comprising the QAM symbols and a indication of a transmission mode, the transmission mode identifying the selected code rate and the QAM constellation selected from the set of candidate QAM constellations,wherein a constant number of RS packets is provided in each of a plurality of transmission frames regardless of transmission mode selected for the each transmission frame.
2 Assignments
0 Petitions
Accused Products
Abstract
A novel framing method for a variable net bit rate digital communications system that utilizes a set of different QAM constellations and punctured trellis code combinations, each combination designated as a mode. This frame structure has a variable integral number of QAM symbols per frame depending on the selected mode, but the number of bytes and Reed-Solomon packets per frame is constant. This is achieved even though the number of data bits per QAM symbol for some modes is fractional. Also the number of trellis coder puncture pattern cycles per frame is an integer for all modes. This arrangement simplifies the synchronization of receiver processing blocks such as the Viterbi decoder, de-randomizer, byte de-interleaver, and Reed-Solomon decoder.
-
Citations
20 Claims
-
1. A method for variable net bit rate digital communications comprising:
-
generating a forward error correction (FEC) data frame from one or more interleaved Reed-Solomon (RS) packets, each RS packet encoding a plurality of data bytes; modulating a plurality of bits of the FEC data frame using a punctured trellis coder that is operated at a selected code rate, the code rate being selected based on white noise performance of a digital communications system; mapping the modulated bits to quadrature amplitude modulation (QAM) symbols using a QAM constellation selected from a set of candidate QAM constellations; and providing a transmission frame comprising the QAM symbols and a indication of a transmission mode, the transmission mode identifying the selected code rate and the QAM constellation selected from the set of candidate QAM constellations, wherein a constant number of RS packets is provided in each of a plurality of transmission frames regardless of transmission mode selected for the each transmission frame. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A method for variable net bit rate digital communications comprising:
-
synchronizing a convolutional byte interleaver to a frame structure; providing a randomized frame to a punctured trellis code modulator, wherein the randomized frame is generated from an interleaved frame of data provided by the convolutional byte interleaver, and wherein the punctured trellis code modulator produces a trellis coded frame from the randomized frame at a code rate that is selected based on a measured white noise performance of a digital communications system; causing a quadrature amplitude modulation (QAM) mapper to map groups of bits in the trellis coded frame to modulation symbols, thereby generating a mapped frame; adding a synchronization packet to the mapped frame; and communicating the mapped frame using the digital communications system. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A non-transitory processor-readable storage medium having one or more instructions which, when executed by at least one processing device, cause the at least one processing device to:
-
synchronize a convolutional byte interleaver to a frame structure; provide a randomized frame to a punctured trellis code modulator, wherein the randomized frame is generated from an interleaved frame of data provided by the convolutional byte interleaver, and wherein the punctured trellis code modulator produces a trellis coded frame from the randomized frame at a code rate that is selected based on a measured white noise performance of a digital communications system; cause a quadrature amplitude modulation (QAM) mapper to map groups of bits in the trellis coded frame to modulation symbols, thereby generating a mapped frame; add a synchronization packet to the mapped frame; and communicate the mapped frame using the digital communications system. - View Dependent Claims (17, 18, 19, 20)
-
Specification