Information To Multiple Users Research Articles

High security optical OFDM transmission scheme with four-dimensional region joint encryption based on power division multiplexing.

In this paper, a high security chaotic encryption scheme for orthogonal frequency division multiplexing (OFDM) transmission system is proposed by using power division multiplexing (PDM) technology and four-dimensional region joint encryption. The scheme uses PDM to realize simultaneous transmission of multiple user information, which can achieve a good compromise among system capacity, spectral efficiency and user fairness. In addition, bit cycle encryption, constellation rotation disturbance (CRD) and region joint constellation disturbance (RJCD) are used to realize four-dimensional region joint encryption, effectively improving the physical layer security. The masking factor is generated by the mapping of two-level chaotic systems, which can enhance the nonlinear dynamics and improve the sensitivity of encrypted system. A 11.76 Gb/s OFDM signal transmission over 25 km standard single-mode fiber (SSMF) is experimentally demonstrated. At the forward-error correction (FEC) bit error rate (BER) limit -3.8×10-3, the proposed receiver optical power based on quadrature phase shift keying (QPSK) without encryption, QPSK with encryption, variant-8quadrature amplitude modulation (V-8QAM) without encryption and V-8QAM with encryption are about -13.5dBm, -13.6dBm, -12.2dBm, and -12.1dBm. The key space is up to 10128. The results show that this scheme not only improves the security of the system and the ability to resist attackers, but also improves the system capacity and has the potential to serve more users. It has a good application prospect in the future optical network.

A Multi-User Collaborative Access Control Scheme Based on New Hash Chain

As the threats to the Internet of Things (IoT) continue to increase, access control is widely used in various IoT information systems. However, due to the shortcomings of IoT devices such as low computing power, it is impossible to use high-performance methods to control user access. Although the emergence of the blockchain provides another way of thinking for access control, the implementation based on the blockchain requires the device to complete the proof of work (PoW) and requires the device to have high computing power. At the same time, most access control schemes existing today are intended for users to use alone, which cannot be applied to the field of multi-user coordinated access. Therefore, this paper proposes a multi-user collaborative access control scheme based on a new hash chain, which uses the identity information of multiple users as the seed value to construct the hash chain, and uses the hash chain as the PoW of the blockchain. An efficiency analysis showed that this method requires only a small amount of hash value calculation and can be applied to IoT systems with low computing power. The security analysis shows that the scheme can resist a variety of attack methods and has high security.

On Optimal Power Allocation in Multibeam Multicast NOMA for Satellite Communication Systems

This paper addresses two key challenges in the multibeam multicast non-orthogonal multiple access (MB-MC-NOMA) scheme and respective beamforming design problems in satellite systems. Achieving the max-min fairness (MMF) and maximum sum-rate among multiple multicast groups of users are jointly considered in a theoretical information framework. It is assumed that each frame contains information of multiple users in multicast transmission. Therefore, contrary to the unicast linear precoding, we have developed the multicast linear precoding with mapping function considering trade-offs to deal with the lack of the spatial degree of freedom. In our proposed scheme, each beamforming vector conveys information to more than one group of users in a NOMA framework, relying on the superposition techniques at the transmitters and successive interference cancellation (SIC) at the receivers. We have derived the capacity rates achievable in each beam, proposing the methods to maximize the minimum rate and weighted sum-rate. Considering the dependency of the broadcasting power and the respective achievable rates, the equivalent channel and water-filling algorithm for the MB-MC-NOMA is developed; as such, the optimal transmit power density for the groups of users within multiple beams are efficiently computed. The extensive simulation results confirm the proposed theoretical findings, providing a considerable boost in both minimum-rate and sum-rate with respect to state-of-the-art multibeam multicast satellite systems.

User Identification Based on Integrating Multiple User Information across Online Social Networks

User identification can help us build more comprehensive user information. It has been attracting much attention from academia. Most of the existing works are profile-based user identification and relationship-based user identification. Due to user privacy settings and social network restrictions on user data crawl, user data may be missing or incomplete in real social networks. User data include profiles, user-generated contents (UGCs), and relationships. The features extracted in previous research may be sparse. In order to reduce the impact of the above problems on user identification, we propose a multiple user information user identification framework (MUIUI). Firstly, we develop multiprocess crawlers to obtain the user data from two popular social networks, Twitter and Facebook. Secondly, we use named entity recognition and entity linking to obtain and integrate locations and organizations from profiles and UGCs. We also extract URLs from profiles and UGCs. We apply the locations jointly with the relationships and develop several algorithms to measure the similarity of the display name, all locations, all organizations, location in profile, all URLs, following organizations, and user ID, respectively. Afterward, we propose a fusion classifier machine learning-based user identification method. The results show that the F1 score of MUIUI reaches 86.46% on the dataset. It proves that MUIUI can reduce the impact of user data that are missing or incomplete.

Flexible Subcarrier Allocation for Interleaved Frequency Division Multiple Access

Interleaved Frequency Division Multiple Access (IFDMA) and Orthogonal FDMA (OFDMA) belong to a class of signal modulation and multiple-access techniques in which information of multiple users are multiplexed and carried on subcarriers within a shared spectrum. Compared with OFDMA, IFDMA has lower Peak-to-Average Power Ratio (PAPR). However, IFDMA poses two rigid constraints on subcarrier allocation: 1) the subcarriers occupied by a user must be evenly-spaced among the available subcarriers. 2) the number of subcarriers used by a user must be a divisor of the total number of subcarriers. This paper investigates how to overcome these constraints to allow flexible and fine-grained subcarrier allocation in IFDMA. Specifically, we put forth 1) a bit-reversal subcarrier allocation scheme whereby the problem of allocating evenly-spaced subcarriers is transformed to a more intuitive problem of filling contiguous bins; 2) a multi-stream IFDMA scheme whereby a user can have an arbitrary number of subcarriers. For the synchronous scenario in which user requests arrive in a synchronous manner, we show that IFDMA can achieve the same level of flexibility and granularity as OFDMA in subcarrier allocation. For the asynchronous scenario in which user requests arrive and depart asynchronously, we show that the blocking probability of IFDMA is only slightly worse than that of OFDMA: specifically, the gap between the blocking probabilities of IFDMA and OFDMA is only 2:56% at a moderate offered load.

특허의 기술이전 활성화를 위한 소셜 태깅기반 지적재산권 추천플랫폼

특허의 기술이전 활성화를 위한 소셜 태깅기반 지적재산권 추천플랫폼

Study on an Algorithm for Generating the Multiple Watermark Information using 2D Barcode

In this paper, we propose a multiple watermarking algorithm which embeds an integrated watermark into content using traditional watermarking algorithm. The integrated watermark consists of multiple watermark information and it is useful to trace illegal distribution. The information is generated by using Dot Code A, which can express multiple user information with error correction. An orthogonal transform and code division multiplexing technology are used to spread Dot Code A. This also ensures the algorithm is robust. The embedding range of the AC coefficients is within [-0.5, -0.3] and [0.3, 0.5] in the discrete cosine transform domain. At an embedding strength of 0.7, the signal-to-noise ratio of the test audio is over 53 dB, and we are able to extract the Dot Code A from the watermarked audio exactly.

Broadcast- and MAC-Aware Coding Strategies for Multiple User Information Embedding

Multiple user information embedding is concerned with embedding several messages into the same host signal. This paper presents several implementable dirty-paper-coding (DPC)-based schemes for multiple user information embedding, through emphasizing their tight relationship with conventional multiple user information theory. We first show that depending on the targeted application and on whether the different messages are asked to have different robustness and transparency requirements or not, multiple user information embedding parallels one of the well-known multiuser channels with state information available at the transmitter. The focus is on the Gaussian broadcast channel (GBC) and the Gaussian multiple access channel (GMAC). For each of these channels, two practically feasible transmission schemes are compared. The first approach consists in a straightforward-rather intuitive-superimposition of DPC schemes. The second consists in a joint design of these DPC schemes. This joint approach heavily relies on a recent work by Kim in which the authors extend the single-user Costa's DPC to the multiple user case. The results in this paper extend the practical implementations quantization index modulation (QIM), distortion-compensated QIM (DC-QIM), and scalar Costa scheme (SCS) that have been originally conceived for one user to the multiple user case. After presenting the key features of the joint design within the context of structured scalar codebooks, we broaden our view to discuss the framework of more general lattice-based (vector) codebooks and show that the gap to full performance can be bridged up using finite dimensional lattice codebooks. Performance evaluations, including bit error rates (BERs) and achievable rate region curves are provided for both methods, illustrating the improvements brought by a joint design

Sounding subband allocation algorithm for proportional fair scheduling in OFDMA∕FDD uplink

A sounding subband allocation algorithm is proposed for a proportional fair (PF) scheduler in an OFDMA/FDD uplink. The proposed sounding algorithm tries to provide a PF scheduler with more proper channel state information of multiple users by using an estimated PF metric. It is shown that the proposed sounding subband allocation algorithm enables the PF scheduler to achieve the throughput gain and guarantee fairness at the same time.

Multiple user information theory

A unified framework is given for multiple user information networks. These networks consist of several users communicating to one another in the presence of arbitrary interference and noise. The presence of many senders necessitates a tradeoff in the achievable information transmission rates. The goal is the characterization of the capacity region consisting of all achievable rates. The focus is on broadcast, multiple access, relay, and other channels for which the recent theory is relativdy well developed. A discussion of the Gaussian version of these channels demonstrates the concreteness of the encoding and decoding necessary to achieve optimal information flow. We also offer speculations about the form of a general theory of information flow in networks.