Digital Currency for Central Bank is becoming an important policy for country. CBDC (Central Bank Digital Currency) model should take advantages in the supervision, payment and consumption. Blockchain possesses the feature of de-centrality, tamper-resistant, and traceability. So this paper attempts to use the blockchain as the fundamental technology of CBDC. However, the challenges such as the protection for users privacy, supervision and transaction speed should be overcome. This paper proposes a CBDC model called MBDC which is based on the permission blockchain technology. The model makes use of the multi-blockchain architecture and ChainID to improve the models scalability and process payments more quickly. In this model, central bank and commercial banks and other agencies build and maintain the blockchain. On one hand, central bank could master the issuance of currency. On the other hand, relying on the user account address protocol, central bank could separate the users identity and transaction information. In this way, central bank could avoid double-spending issues and protect users privacy. In addition, the establishment of DC (Data Center) and layers of supervision provide strong supervision for the model. Finally, we also demonstrate, both theoretically and experimentally, the performance of model on the scalability and the speed of transaction execution etc.

Motivation: Short Interspersed Nuclear Elements (SINEs) are transposable elements (TEs) that amplify through a copy-and-paste mode via RNA intermediates. The computational identification of new SINEs are challenging because of their weak structural signals and rapid diversification in sequences. Results: Here we report SINE_Scan, a highly efficient program to predict SINE elements in genomic DNA sequences. SINE_Scan integrates hallmark of SINE transposition, copy number and structural signals to identify a SINE element. SINE_Scan outperforms the previously published de novo SINE discovery program. It shows high sensitivity and specificity in 19 plant and animal genome assemblies, of which sizes vary from 120 Mb to 3.5 Gb. It identifies numerous new families and substantially increases the estimation of the abundance of SINEs in these genomes. Availability and Implementation: The code of SINE_Scan is freely available at http://github.com/maohlzj/SINE_Scan , implemented in PERL and supported on Linux. Contact: [email protected]. Supplementary information: Supplementary data are available at Bioinformatics online.

With the ever-increasing demands for local area services of popular content sharing, device-to-device (D2D) communication is conceived to be a key component for the next-generation cellular networks. D2D communications consume low energy and enhance system capacity via proximity range transmissions, where multi-hop transmissions are needed for real-time content sharing. Aiming to solve the challenging problem for multi-hop D2D communication networks, existing works only consider physical domain information to create Long-range Links (LLs) to reduce the transmission delay of multi-hop. In contrast, in this paper, we propose social community aware LLs establishment strategy, which exploits the interplay between social network's features and physical domain constrains. We first formulate the LLs establishment strategy as a cost optimization problem, then propose an efficient optimal greedy algorithm to solve the formulated problem, which is suitable for scenarios of both single sink and distributed content sharing. Numerical results demonstrate that our proposed solution decreases the average path length significantly compared with other state-of-the-art schemes.

In the downlink transmission system with a multi-antenna base station (BS) and a cluster of single-antenna mobile stations (MSs), the throughput can be greatly enhanced by exploiting the cooperating channel among MSs and forming virtual multiple input and multiple output (MIMO). With MSs close together, compress-and-forward is the most commonly used cooperation strategy. Considering the fact that in practical systems the transmit signal is usually finite-alphabet modulated symbols, e.g., quadrature amplitude modulation (QAM), the compress-and-forward cooperation is investigated correspondingly. Regarding the bit error rate (BER) performance of virtual MIMO systems, two regions are identified: the channel-noise-dominant region and the compression-noise-dominant region. In the channel-noise-dominant region, the cooperation system yields almost no loss compared to the BER lower bound. While in the compression-noise-dominant region, the system BER is limited, i.e., with an error floor. Through theoretical analysis, the minimum compression rate to guarantee that the system works in the channel-noise-dominant region is obtained. The minimum compression rate is determined mainly by three terms: the modulation alphabet size, the constellation position and the signal-to-noise ratio (SNR), whose explicit expression has also been derived.

It has been long believed that the turbo equalizer leveraging a soft input/soft output (SISO) detector is effective for system performance enhancement in terms of bit error rate (BER). In practical applications, the implementation of SISO detection is usually challenging, due to its high computational-complexity. To address this issue, this paper proposes a low complexity SISO detector based on QR decomposition (QRD) and the M-search algorithm for single carrier block transmission systems. Benefiting from two unique properties called the aggregation property and the natural ordering property obtained by applying the QRD method into single carrier block transmission systems, the QRD-M based SISO detection algorithm can be dramatically simplified. Detailed analysis shows a linear growing computational-complexity. The extrinsic information transfer (EXIT) chart analysis tool is used to illustrate the performance of the proposed scheme. Both EXIT analysis and simulation results reveal that the turbo equalization with the proposed QRD-M detection algorithm could achieve a sub-optimal system performance close to the BER-optimal maximum a posteriori (MAP) detector at each iteration with a much lower computational-complexity.

While channel state information (CSI) at the transmitter is critical to the system capacity of multiple input multiple output (MIMO) broadcast channels, its acquisition is practically intricate. This paper offers an alternative and investigates a special MIMO broadcast channel, which exploits the benefit of receiver cooperation and renders it unnecessary to acquire CSI at the transmitter. The cooperation gain is studied in a system-wide perspective by taking into account the resource (power and bandwidth) consumed to establish the cooperation links. Built on that, the generalized cooperation spectral efficiency is defined.With a dedicated approximation, a near optimal resource allocation strategy is presented to maximize the cooperation spectral efficiency. Specially, the power allocation problem is simplified into a polynomial rooting problem. Simulation results show that the receiver cooperation can provide a performance gain and achieve the MIMO capacity. Moreover, performance loss incurred by the proposed method is negligible compared to the numerical exhaustive search scheme.

The frequency selective fading channels cause severe inter-symbol interference (ISI) and significantly degrade the bit error rate (BER) performance of broadband wireless communication systems. In this paper, a soft detection algorithm employing the idea of QR decomposition, data grouping and successive interference cancelation (SIC) is proposed for coded single carrier (SC) block transmission. We show that SC block transmission with unique word (UW) brings two unique features while employing the QRD detection method. We refer to them as the natural ordering property and the sparse property, respectively. The data block is divided into small groups and the log-likelihood ratio (LLR) of each element is derived from the bottom up. A flexible tradeoff between BER performance and detection complexity can be provided. Simulation results show that in frequency selective fading channels, the proposed scheme can obtain dramatic performance gain compared to the minimum mean square error (MMSE) single carrier frequency domain equalization(FDE) with low complexity.

The time-frequency interleave (TFI) diversity scheme for single carrier block transmission with frequency domain equalization (SC-FDE) has been proposed. For single antenna wireless communication systems, it can provide frequency diversity in frequency selective channels by interleaving and retransmitting. In this article, the iterative block decision feedback equalization (IBDFE) structure for TFI diversity scheme is proposed. Both the feed-forward filter (FFF) and feed-backward filter (FBF) work in the frequency domain, which makes the implementation complexity low. The FFF and FBF coefficients based on minimum mean square error (MMSE) criterion are derived. The correlation between the transmitted symbols and the detected symbols are estimated in a simple iterative manner. Simulation results show that for TFI diversity scheme with IBDFE, a much better bit error rate (BER) performance can be obtained than TFI with frequency domain linear equalizer (FD-LE) only for one more iteration. Compared to IBDFE without TFI diversity, the performance gain is impressive.