Codebook

About: Codebook is a research topic. Over the lifetime, 8492 publications have been published within this topic receiving 115995 citations.

Fully vector-quantized subband coding with adaptive codebook allocation

Abstract: Vector quantization (VQ) is examined as a technique to enhance performance in subband coding of speech at 9.6 kb/s. The set of short-term subband power levels is vector quantized, providing low-rate side information to control the coding of the subband signals. Each subband signal is then vector quantized with variable size codebooks that are dynamically assigned by the quantized side information. Two versions are described, a 7-band coder and a 14-band coder. Simulation results demonstrate that vector quantization offers a distinct perceptual improvement compared with scalar quantization of the same subband signals and side information for the same total bit rate.

Speech coding system and a method of encoding speech

Abstract: A speech coding system of the code excited linear prediction (CELP) type comprises means (24,26) for filtering digitised speech samples to form perceptually weighted speech samples. Entries in a one-dimensional codebook (110) comprising frame length sequences are filtered in a perceptually weighted synthesis filter (28) to form a one-dimensional filtered codebook (38). The filtered codebook entries are compared with the perceptually weighted speech signals to obtain a codebook index which gives the minimum perceptually weighted error when the speech is resynthesised. Using a one-dimensional codebook (110) reduces the amount of computation which is required compared to using a two-dimensional codebook.

Downlink wireless transmission schemes with inter-cell interference mitigation

Abstract: A system and method for inter-cell interference avoidance. A device capable of performing channel estimation is configured to divide a codebook into two sets. A first set of said two sets corresponds to codebook information that will cause an interference in a received signal to be less than a threshold. The device further is configured to send feedback information corresponding to the first or second set, or both. A base station is configured to select a precoding vector or matrix based, in part, on a portion of the feedback information.

Adaptive edge-based side-match finite-state classified vector quantization with quadtree map

Abstract: Vector quantization (VQ) is an effective image coding technique at low bit rate. The side-match finite-state vector quantizer (SMVQ) exploits the correlations between neighboring blocks (vectors) to avoid large gray level transition across block boundaries. A new adaptive edge-based side-match finite-state classified vector quantizer (classified FSVQ) with a quadtree map has been proposed. In classified FSVQ, blocks are arranged into two main classes, edge blocks and nonedge blocks, to avoid selecting a wrong state codebook for an input block. In order to improve the image quality, edge vectors are reclassified into 16 classes. Each class uses a master codebook that is different from the codebooks of other classes. In our experiments, results are given and comparisons are made between the new scheme and ordinary SMVQ and VQ coding techniques. As is shown, the improvement over ordinary SMVQ is up to 1.16 dB at nearly the same bit rate, moreover, the improvement over ordinary VQ can be up to 2.08 dB at the same bit rate for the image, Lena. Further, block boundaries and edge degradation are less visible because of the edge-vector classification. Hence, the perceptual image quality of classified FSVQ is better than that of ordinary SMVQ.

A Novel and Efficient Vector Quantization Based CPRI Compression Algorithm

Abstract: The future wireless network, such as the Centralized Radio Access Network (C-RAN), will need to deliver data rate about 100–1000 times the current fourth-generation (4G) technology. For the C-RAN-based network architecture, there is a pressing need for tremendous enhancement of the effective data rate of the common public radio interface (CPRI). Compression of CPRI data is one of the potential enhancements. In this paper, we introduce a vector quantization based compression algorithm for CPRI links, utilizing the Lloyd algorithm. Methods to vectorize the I/Q samples and enhanced initialization of the Lloyd algorithm for codebook training are investigated for improved performance. Multistage vector quantization and unequally protected multigroup quantization are considered to reduce codebook search complexity and codebook size. Simulation results show that our solution can achieve compression of four times for uplink and 4.5 times for downlink, within $2\%$ error vector magnitude (EVM) distortion. Remarkably, vector quantization codebook proves to be quite robust against data modulation mismatch, fading, signal-to-noise ratio (SNR), and Doppler spread.