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Quantization Index Modulation is an important class of watermark methods, which has been widely used in blind watermark applications. And it is well known that spread transform dither modulation (STDM), as an extension of QIM, has good performance in robustness to random noise and re-quantization. However, the quantization step sizes used in STDM are random numbers not taking the feature of the image...
Cooperative diversity is a promising and practical technique for realizing spatial diversity through a virtual antenna array formed by multiple distributed antennas of different nodes. In this paper, we propose and evaluate a novel cooperative cross-layer medium access control (CC-MAC) protocol, which combines space-time coding and adaptive modulation at the physical layer and employs truncated automatic...
In the paper, the original image is divided into four parts by two different methods, which are taken as the observation signals in Independent Component Analysis (ICA) model. Then the watermark is embedded into DCT domain of the feature with the largest variance using iterative Adaptive Quantization Index Modulation (AQIM) and AQIM algorithms respectively. By comparing the performance of four kinds...
UST symbol-based turbo code has recently been proposed which can reduce the system complexity and calculation amount compared with bit-wise concatenation scheme. However, the corresponding MAP decoding algorithm still makes hardware unbearable and later its simplified versions, Max-Log-MAP and Log-MAP algorithms, appeared. In this paper, we propose a multiary SOVA decoding algorithm for UST symbol-based...
Space time coding in the case where the channel state information is unknown has received only limited attention, although a signaling scheme called unitary space-time modulation (USTM) has already been proposed. An important reason for the impracticability of USTM is its too large calculation amount when meeting with a large size constellation. We propose a size-reduced method for constellation of...
Recently, a novel scheme employing unitary space-time symbol based turbo code (USTSBTC) has been proposed that can greatly reduce the system complexity while maintaining a fairly well performance compared with the bit wise processing version. However, as we know, an intrinsic pitfall of MAP decoding algorithm for turbo code is its too large amount storage requirement. We propose a sliding window for...
We propose a scheme of utilizing unitary space-time symbol based nonbinary turbo code (USTSBTC) for wireless communication systems with multiple antennas over extremely fast Rayleigh block fading channels, where no channel state information (CSI) is available. We give an effective way of applying USTSBTC as an alternative to the original unitary space-time modulation and present an effective unitary...
Quantization index modulation (QIM) algorithm is one of the most important blind detection watermarking algorithm. The adaptive quantization index modulation (AQIM), proposed by I. J. Cox, calculates the quantization step according to the Watsonpsilas perceptual model, and makes the embedding steps vary according to the coefficients to be quantized adaptively. It has better reliability and robustness...
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