Codebook

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

Digital speech coder having improved vector excitation source

Abstract: An improved excitation vector generation and search technique (FIG. 1) is described for a code-excited linear prediction (CELP) speech coder (100) using a codebook of excitation code vectors. A set of M basis vectors Vm (n) are used along with the excitation signal codewords (i) to generate the codebook of excitation vectors ui (n) according to a "vector sum" technique (120) of converting the selector codewords into a plurality of interim data signals, multiplying the set of M basis vectors by the interim data signals, and summing the resultant vectors to produce the set of 2M codebook vectors. The entire codebook of 2M possible excitation vectors is efficiently searched by using the vector sum generation technique with the M basis vectors--without ever having to generate and evaluate each of the 2M code vectors themselves. Furthermore, only M basis vectors need to be stored in memory (114), as opposed to all 2M code vectors.

Codebook generation system and associated methods

Abstract: The invention relates to a codebook generation system and associated methods. The invention are generally directed to communication systems and, more particularly, to a codebook generation system and associated methods. In one embodiment, a device is disclosed and comprises a processor circuit. The processor circuit is arranged to select a pre-coding matrix based on an index which is received from remote equipment through a communication channel of a closed-loop multi-input multi-output (MIMO) orthogonal frequency-division multiplexing (OFDMA) system. The pre-coded matrix is built through applying conversion on one or multiple vectors. Information is precoded through the pre-coding matrix for transmitting through a plurality of transmitter antennae. The invention further discloses the codebook generation system and the associated methods.

BER Analysis and Optimization of Generalized Spatial Modulation in Correlated Fading Channels

Abstract: We propose and analyze a generalized spatial mod- ulation scheme, where depending on the bits to be transmitted a certain data symbol as well as a certain beamforming vector is chosen. The receiver then has to estimate both the used beamforming vector and the transmitted data symbol for being able to reconstruct the originally transmitted bit sequence. We analyze our scheme theoretically by deriving a very tight upper bound on the average bit error rate (BER) for arbitrary symbol constellations and beamforming codebooks in correlated Rayleigh fading channels. Based on this bound, we determine a design criterion for optimizing the used beamforming codebook in presence of spatial correlation at the transmitter-side. Simulation results are shown to be in excellent agreement with our analytical calculated BERs and they illustrate the significant performance gains that can be obtained with our generalized scheme compared to conventional spatial modulation.

Signal generation using phase-shift based pre-coding

Abstract: A phase-shift based pre-coding scheme used in a transmitting side and a receiving side that has less complexity than those of a space-time coding scheme, that can support various spatial multiplexing rates while maintaining the advantages of the phase-shift diversity scheme, that has less channel sensitivity than that of the pre-coding scheme, and that only requires a low capacity codebook is provided.

Vector excitation speech or audio coder for transmission or storage

Abstract: A vector excitation coder efficiently com-presses vectors by using an optimum codebook designed off line, using an initial arbitrary codebook and a set of speech training vectors exploiting codevector sparsity (i.e., by making zero all but a selected number of samples of lowest amplitude in each of N codebook vectors). A fast-search method selects a number Nc of good excitation vectors from the code-book, where Nc is much smaller than N, and uses only the Nc vectors in an exhaustive search for the best match between a perceptually weighted input vector Zn~ and an estimate Zn derived from a codebook vector processed through long-term and short-terms filters, and a perceptual weighting filter. The zero input response of these cascaded filters is calculated and subtracted from an input speech vector sn after per-ceptual weighting to produce a vector rn. The code-book search operation is performed using