Scrambling for probabilistic constellation schemes in wireless communications

A method for wireless communications at a first wireless device, comprising:

• encoding a set of information bits of a transport block for transmission to a second wireless device;
• performing a distribution matching procedure on the encoded set of information bits according to a probabilistic constellation shaping scheme to obtain an encoded set of distributed bits;
• scrambling the encoded set of distributed bits after the distribution matching procedure;
• modulating the scrambled encoded set of distributed bits based at least in part on one or more constellations associated with the probabilistic constellation shaping scheme to obtain a codeword associated with the transport block;
• and
• transmitting the codeword to the second wireless device.

A method for wireless communications at a first device, comprising:

• receiving, from a second wireless device, a codeword associated with a transport block;
• performing a modulation procedure on the codeword in accordance with a probabilistic constellation shaping scheme to obtain an encoded set of distributed amplitude bits associated with the codeword;
• performing the modulation procedure on a scrambled set of sign bits of the codeword;
• decoding the encoded set of distributed amplitude bits to obtain a set of distributed amplitude bits associated with the codeword;
• performing a distribution matching procedure on the set of distributed amplitude bits to obtain a set of scrambled amplitude bits;
• and
• descrambling the set of scrambled amplitude bits and the scrambled set of sign bits to obtain a set of information bits associated with the transport block, wherein the scrambled set of sign bits are descrambled based at least in part on an index value associated with a number of the set of information bits or are descrambled based at least in part on a default index value associated with the scrambled set of sign bits.

A method for wireless communications at a first wireless device, comprising:

• receiving, from a second wireless device, a codeword associated with a transport block;
• demodulating the codeword based at least in part on one or more constellations associated with a probabilistic constellation shaping scheme to obtain an encoded set of distributed bits associated with the transport block;
• performing a distribution matching procedure on the encoded set of distributed bits according to the probabilistic constellation shaping scheme to obtain an encoded set of information bits associated with the transport block;
• descrambling the encoded set of information bits after the distribution matching procedure;
• and
• decoding the encoded set of information bits associated with the transport block to obtain a set of information bits associated with the transport block.

An apparatus for wireless communications at a first wireless device, comprising:

• a processor;
• memory coupled with the processor;
• and
• instructions stored in the memory and executable by the processor to cause the apparatus to:
• scramble a set of amplitude information bits associated with a transport block for transmission to a second wireless device;
• scramble a set of sign bits associated with the transport block based at least in part on an index value associated with a number of the set of amplitude information bits or at least in part on a default index value associated with the set of sign bits;
• perform a distribution matching procedure on the scrambled set of amplitude information bits to obtain a set of distributed amplitude bits;
• encode the set of distributed amplitude bits;
• perform a modulation procedure on the encoded set of distributed amplitude bits and on the scrambled set of sign bits in accordance with a probabilistic constellation shaping scheme to obtain a codeword associated with the transport block;
• and
• transmit the codeword to the second wireless device.