4 results about "Variable-length code" patented technology

The invention belongs to the technical field of communication, and particularly relates to a semantic communication method combining variable length coding and constellation probabilistic shaping, which comprises the following steps of: firstly, constructing a semantic encoder based on a mask auto-encoder framework, and designing a mask rate control function through channel state information and information source characteristics so as to dynamically adjust an information source mask rate; a self-adaptive variable-length coding mechanism is realized; according to the obtained mask rate, sampling a non-masked information source unit by adopting a maximum entropy criterion so as to reserve the information amount of the information source to the maximum extent; the constellation point optimal probability is shaped and approximated to discrete two-dimensional Gaussian distribution, and an end-to-end optimization target is deduced based on variational inference; semantic feature coding distribution is constrained through layer normalization operation to approximate Gaussian prior, so that an objective function is effectively simplified; and finally, designing a quantization modulator of semantic feature-constellation point identical distribution mapping based on finite scalar quantization, and adopting a gradient straight-through estimator to solve the non-differentiable problem of the quantization process, and finally realizing end-to-end joint optimization of the system.

Wedgelet-based coding for coding blocks of varying size is rendered more efficient by the usage of a variable length coded syntax element having a prefix and a suffix, wherein the size of the suffix is dependent on the prefix and the size of the current coding block. By this measure, it is feasible to efficiently adapt the length of the variable-length coded syntax element which controls the bi-partitioning of the current coding block to the actual needs, namely the size, of the current coding block, and the variability of the bi-partitioning by varying the wedglet separation line, respectively. The greater the current coding block is, the longer the variable-length coded syntax element may be. This length dependency may even be sufficiently effective in terms of coding efficiency so that the variable length coded syntax element may be coded without context-adaptive entropy coding, but directly or using fixed-equal-probability binary entropy coding.

In one implementation, we propose to use coset decomposition to improve intra prediction mode coding and decoding. In 67 intra-frame prediction modes, 64 prediction modes are selected for coset decomposition, and the remaining three modes are left in a reduced MPM (most probable mode) list. 64 modes are decomposed into cosets, wherein the number of cosets and the number of modes in the cosets are determined by the size of the target block and / or statistics of intra prediction modes of neighboring blocks. And the intra-frame prediction modes in the cosets are arranged according to a likelihood decreasing sequence. The intra prediction mode of the target block is encoded as a coset index and a member index in the coset. The first coset, namely the first mode in the coset, is encoded with bit 0, and the remaining modes are encoded with fixed or variable length codes.

The invention provides a channel state information feedback method and device based on an adaptive feedback rate. The method comprises the following steps: acquiring a channel state information matrix; inputting the sequence into a pre-training marking encoder based on an attention mechanism, and converting the sequence into a symbol sequence with a fixed length; quantizing the symbol sequence into a discrete index sequence through a pre-training vector quantizer and a codebook; determining a target length according to a real-time channel condition or a dynamically allocated system feedback resource based on a preset importance sorting rule obtained by nesting and discarding training, truncating an index sequence arranged according to an importance descending order, and retaining a front-end index to generate a variable-length feedback code word; and sending the variable-length code word to a base station for reconstruction. According to the method, the dynamic self-adaptive optimization of the feedback rate is realized, the spectrum efficiency is effectively improved, the progressive reconstruction is supported by utilizing the inherent importance sorting of the code words, and the robustness of the system is remarkably enhanced.