Shuping Dang’s research while affiliated with University of Bristol and other places

In the online social networks (OSNs) and social Internet of Things (SIOT), communities of interest (CoI) are often used to facilitate information sharing among user devices. However, the risk of information leaks across communities persists due to inadequate control over users' sharing behavior. In this paper, we propose a novel trust-based community sharing mechanism to control users who are contributing to high privacy leakage across communities of an OSN. In detail, we firstly formulate privacy loss in community based on the sensitivity and willingness of users in sharing. Secondly, we use this loss as the key determinant when updating trust to dynamically hold users accountable for privacy leakage. Thirdly, we use an adjustable threshold to enable or disable sharing users and evaluate the amount of information shared before and after control, as well as the changes in community user trust. Finally, we propose an optimization method based on the upper confidence bound to make a trade-off between information sharing and leakage through a payoff function over discretized thresholds. Simulations on three real OSNs datasets — BlogCatalog, Flickr, and YouTube — demonstrated that our proposed mechanism can effectively reduce community privacy loss by achieving the best payoff score of 1076.53, while the state-of-the-art baselines PDC-InfoSharing and UTV scored 506.33 and 957.98, respectively.

Reconfigurable intelligent surface (RIS) and ambient backscatter communication (AmBC) technologies are recognized for their programmability and high energy efficiency respectively, which will be the key parts of the future sixth generation (6G) mobile communication technology. The combination of the two technologies can improve communication security by reducing the probability of detection and decoding through enhanced transmission and backscatter transmission in different communication slots. In this paper, a dual-function RIS that supports cooperative relaying for covert communications is proposed. It operates in different communication slots (enhanced transmission slot and backscatter slot), but the performance is affected by phase errors due to function switching. A source covertly communicates with an intended destination via the help of RIS and cooperative relay. There is an illegal monitor aims to detect and eavesdrop the covert message. For this system, the outage probability (OP), intercept probability (IP), and detection error probability (DEP) in different communication slots are derived to examine the system reliability and security. Moreover, the system security probability (SSP) is proposed, and a block coordinated ascent (BCA)-based iterative algorithm is used to jointly optimize the power allocation coefficients to maximize the SSP. Simulation results show that increasing the number of elements can improve the security performance and mitigate the negative impact of RIS phase errors.

Blockchain plays a key role in establishing secure and decentralized Industrial Internet of Things (IIoT) systems. Currently, the dependent transactions generated by IIoT devices require a packing process to select a set of non-conflicted transactions, which results in significant delay and deviation of the transaction response time. In this paper, we propose a novel transaction packing algorithm named Priority-Pack to address the above issue. Firstly, we use directed acyclic graphs to model the dependent transactions in IIoT systems to establish the mathematical relationships between transaction priority and waiting time as well as dependencies. Secondly, we propose an algorithm to specify a higher priority to a transaction with longer waiting time without violating transaction dependencies. It eliminates the time required to traverse the subsets of transactions in other algorithms. Thirdly, to further reduce the response delay for transactions with the same priority level, we choose to first pack transactions with smaller sizes. We prove that this selection can achieve the lowest average response time. Finally, simulations are conducted to benchmark the Priority-Pack against the state-of-the-art algorithms including Fair-Pack and Random-Pack. The results demonstrate that Priority-Pack outperforms the others in terms of average response time and deviations.

This paper investigates the resource management problem in multi-carrier rate-splitting multiple access (MC-RSMA) systems with imperfect channel state information (CSI) and successive interference cancellation (SIC) for ultra-reliable and low-latency communications (URLLC) applications. Effective throughput (ET) is employed as the key performance metric in this study to explore the trade-off between the decoding error probability and achievable rate. A mixed-integer non-convex problem is formulated to jointly optimize power allocation, rate control, and user grouping. To tackle this challenge, the achievable ET is approximated using a lower bound, and a decomposition approach is developed to decouple the optimization variables. Specifically, for a given user grouping scheme, an iteration-based concave-convex programming (CCCP) method and an iteration-free lower-bound approximation (LBA) method are proposed for power allocation and rate control. Furthermore, a greedy search-based scheme and a minimum correlation user grouping (MCUG) scheme are designed for the user grouping problem. Simulation results verify the effectiveness of the CCCP and LBA methods in power allocation and rate control and the MCUG method in user grouping when compared to the greedy and random methods. Besides, the superiority of RSMA for URLLC services is demonstrated when compared to spatial division multiple access.

With the flourishing development of 6G wireless networks, the demand of spectrum efficiency rapidly increases, in order to support the demands of high quality data transmission and connections of massive users. Among various promising technologies, the technology of near-field communications provides a great potential to address such an issue due to the unique spherical-wave channels for electromagnetic (EM) propagation. In this paper, multiple-input single-output (MISO) near-field communications is comprehensively studied to clarify the influences of the shape and structure of uniform planar array (UPA) on the system performance, considering three cases with uniform linear array (ULA), rectangular UPA, and circular UPA. In particular, we reveal the properties of rapid deterioration for signal-to-noise ratio (SNR) from the reduced projection aperture in near-field communications and investigate the single spherical crown antenna design and spherical crown antenna array design in order to address this issue. Moreover, we also characterize the role of antenna projection aperture in details, and theoretically analyze the shape of UPA, yielding the corresponding exact closed-form expressions for SNR and outage probability (OP). Based on these above analytical results, we find out that adjusting the spacing between adjacent antennas to control the relative angle between user and selected antennas is an efficient way to improve the projection aperture of antenna and SNR. Simulation results are shown to well match analytical results, which validate the correctness of our analysis, clarifying that our proposed designs outperform the conventional works and illustrating a better stability for angle variations.

This paper investigates the uplink power control scheme for massive multiple-input and multiple-output non-orthogonal multiple access (mMIMO-NOMA) in massive ultra-reliable and low-latency communications (mURLLC) for Industrial Internet of Things (IIoT) applications. By the proposed NOMA scheme, the connected sensors are divided into several groups, and only group-level successive interference cancellation (GL-SIC) is considered at the receiver to reduce the decoding complexity and processing delay. Two schemes, i.e., mMIMO-NOMA with and without pilot sharing, are developed to fully explore the superiority of mMIMO-NOMA in mURLLC with a finite blocklength. For both schemes, the closed-form expressions of the achievable rate are obtained for the minimum mean square error (MMSE) estimator and zero-forcing (ZF) detector. Next, to address the formulated sum rate maximization problem, we develop a successive condensation approach (SCA)-based algorithm to jointly optimize pilot and data power. Besides, the max-min fairness (MMF) rate is also analyzed by verifying the feasibility of the problem. Finally, the simulation results demonstrate the effectiveness of the proposed SCA power control scheme. In addition, the advantages of the proposed two NOMA schemes in both sum rate and sum MMF rate are verified compared to traditional multi-user MIMO systems in mURLLC scenarios.

This paper incorporates the concept of generalized pre-coded quadrature spatial modulation (GPQSM) into non-orthogonal multiple access (NOMA) systems aided by simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) to boost spectral efficiency. The proposed GPQSM-STAR-RIS-NOMA scheme allows for the conveyance of additional information bits to different users according to a pre-coding scheme for adapting the subsurface allocation patterns. Furthermore, we derive an approximate expression for the bit error rate. Simulation results demonstrate that our proposed scheme achieves a better transmission rate than the conventional STAR-RIS-NOMA scheme.

In this paper, we propose employing the index modulation to improve the overall system performance and physical layer security in non-orthogonal multiple access (NOMA) networks with an near untrusted user. In the proposed scheme, by virtue of dynamically shifting the antenna activation patterns and energy allocation patterns, an untrusted user located near the base station (BS) can only successfully decode its own information generated by modulated symbols, while the information encoded by antenna and energy combination indices intended for other trusted users located far away from the BS cannot be decoded. Additionally, the secrecy rate is derived to evaluate the performance of the proposed NOMA networks. Simulation results validate the proposed scheme and provide insights into the design for far trusted users to prevent eavesdropping launched by near untrusted users in NOMA networks.

Polarization-spatial modulation (PSM) has been recently proposed to improve the system performance and energy efficiency of the conventional polarization modulation (PM) by activating only a single dual-polarized (DP) antenna for signal transmission. However, the spectral efficiency (SE) of PSM is significantly degraded due to the single DP antenna transmission. To tackle this problem, we propose a generalized PSM (GPSM) scheme to enhance the SE of PSM through transmission using multiple DP antennas. In the GPSM scheme, the information bits are mapped to antenna activation patterns (AAPs), polarization matrix activation patterns (PAPs), and modulated symbols. To further enhance the SE of GPSM, we propose a more practical scheme termed multi-mode GPSM (MM-GPSM), which transmits information bits not only through the AAPs, PAPs, and modulated symbols but also via the constellation activation patterns (CAPs). A low-complexity maximum likelihood (ML) detector and a log-likelihood ratio detector for both GPSM and MM-GPSM are proposed to relieve the high computational complexity of the optimal ML detector at the cost of a negligible performance loss. An upper bound on the bit error rate (BER) is derived in closed-form to evaluate the performance of both GPSM and MM-GPSM. Simulation results show that GPSM and MM-GPSM outperform the conventional PM and PSM schemes, particularly in the high signal-to-noise ratio (SNR) region, and verify the accuracy of the theoretical analysis of the upper-bounded BER.