Non-orthogonal multiple access (NOMA) is the technique proposed for multiple access in the fifth generation (5G) cellular network. In NOMA, different users are allocated different power levels and are served using the same time/frequency resource blocks (RBs). The main challenges in existing NOMA systems are the limited channel feedback and the difficulty of merging it with advanced adaptive coding and modulation schemes. Unlike formerly proposed solutions, in this paper, we propose an effective channel estimation (CE) algorithm based on the long-short term memory (LSTM) neural network. The LSTM has the advantage of adapting dynamically to the behavior of the fluctuating channel state. On average, the use of LSTM results in a 10% lower outage probability and a 37% increase in the user sum rate as well as a maximal reduction in the bit error rate (BER) of 50% in comparison to the conventional NOMA system. Furthermore, we propose a novel power coefficient allocation algorithm based on binomial distribution and Pascal’s triangle. This algorithm is used to divide power among N users according to each user’s channel condition. In addition, we introduce adaptive code rates and rotated constellations with cyclic Q-delay in the quadri-phase shift keying (QPSK) and quadrature amplitude modulation (QAM) modulators. This modified modulation scheme overcomes channel fading effects and helps to restore the transmitted sequences with fewer errors. In addition to the initial LSTM stage, the added adaptive coding and modulation stages result in a 73% improvement in the BER in comparison to the conventional NOMA system.
In this paper, a novel Commutative Watermarking and Partial Encryption (CWPE) algorithm based on Discrete Wavelet Transform and Discrete Cosine Transform (DWT-DCT) for watermarking and Multi-Map Wavelet Chaotic Encryption (MMW-CE) is proposed. The original host image is first decomposed into four sub-bands using (DWT), each sub-band coefficients are relocated using Arnold transform to create a noiselike version, then apply partial encryption scheme using chaotic scrambled random number pattern bitwise XOR with the scrambled horizontal coefficients only and the shuffled approximation coefficients are divided into non-overlapping and equal sized blocks. Watermark embedding process is based on extracting the (DCT) middle frequencies of the encrypted approximation coefficients blocks. Comparison based threshold of the extracted DCT mid-band coefficients, watermark bits are embedded in the coefficients
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