High levels of scalability and reliability are needed to support the massive Internet-of-Things (IoT) services. In particular, blockchains can be effectively used to safely manage data from ...large-scale IoT networks. However, current blockchain systems have low transactions per second (TPS) rates and scalability limitations that make them unsuitable. To solve the above issues, this article proposes a deep <inline-formula> <tex-math notation="LaTeX">Q </tex-math></inline-formula> network shard-based blockchain (DQNSB) scheme that dynamically finds the optimal throughput configuration. In this article, a novel analysis of sharded blockchain latency and security-level characterization is provided. Using the analysis equations, the DQNSB scheme estimates the level of maliciousness and adapts the blockchain parameters to enhance the security level considering the amount of malicious attacks on the consensus process. To achieve this purpose, deep reinforcement learning (DRL) agents are trained to find the optimal system parameters in response to the network status, and adaptively optimizes the system throughput and security level. The simulation results show that the proposed DQNSB scheme provides a much higher TPS than the existing DRL-enabled blockchain technology while maintaining a high security level.
In this article, a deep reinforcement learning (DRL) control scheme is proposed to satisfy the strict Quality-of-Service (QoS) requirements of ultrareliability low-latency communication (URLLC) and ...enhanced mobile broadband (eMBB) using 5G multiple radio access technology (RAT)-based partial offloading and multiaccess edge-computing (MEC) resource allocation. In the proposed scheme, the user equipment (UE) makes optimal offloading decisions while the MEC server dynamically adjusts the server resources based on offloading requests from multiple UEs using DRL technology. The aim of the proposed scheme is to minimize the energy consumption of the UEs while maximizing the system utility (SU) performance, which is composed of the spectral efficiency (SE) and offloading success rate (OSR) of the MEC server. In addition, multiagent distributed learning technology and best experience push (BEP) techniques are used to enhance the learning efficiency of the DRL framework. The simulation result shows that the proposed scheme provides an improved SU and energy consumption performance compared to the benchmark offloading schemes.
In this letter, a resource allocation scheme for 5G new radio (NR) based vehicle-to-vehicle (V2V) sidelink mode 1 unicast communication is proposed. First, a M/G/1 queueing model-based end-to-end ...(E2E) latency analysis on the communication methodology is performed considering packet retransmissions. Based on the latency requirements of NR-V2V unicast traffic, a Sidelink Unicast V2V Real-time (SUVR) scheme is proposed to minimize the required number of resource blocks (RBs). Simulation results show that the proposed SUVR scheme provides more efficient resource management at the gNodeB, while satisfying the packet latency quality of service (QoS) requirements for vehicular user equipment compared to the benchmarked VRSAP scheme.
Blockchains guarantee data integrity through consensus of distributed ledgers based on multiple validation nodes called miners. For this reason, any blockchain system can be critically disabled by a ...malicious attack from a majority of the nodes (e.g., 51% attack). These attacks are more likely to succeed as the number of nodes required for consensus is smaller. Recently, as blockchains are becoming too large (making them difficult to store, send, receive, and manage), sharding is being considered as a technology to help improve the transaction throughput and scalability of blockchains. Sharding distributes block validators to disjoint sets to process transactions in parallel. Therefore, the number of validators of each shard group is smaller, which makes shard-based blockchains more vulnerable to 51% attacks than blockchains that do not use sharding. To solve this problem, this paper proposes a trust-based shard distribution (TBSD) scheme that assigns potential malicious nodes in the network to different shards, preventing malicious nodes from gaining a dominating influence on the consensus of a single shard. TBSD uses a trust-based shard distribution scheme to prevent malicious miners from gathering in on one shard by integration of a trust management system and genetic algorithm (GA). First, the trust of all nodes is computed based on the previous consensus result. Then, a GA is used to compute the shard distribution set to prevent collusion of malicious miners. The performance evaluation shows that the proposed TBSD scheme results in a shard distribution with a higher level of fairness than existing schemes, which provides an improved level of protection against malicious attacks.
Wireless networks are vulnerable to various network attacks. To cope with these security issues, trust-based routing schemes have emerged. Typically, trust routing schemes are mainly focused on ...detection of packet drop attacks, because this type of an attack is simple and obviously a malicious behavior. However, there are more advanced attacks, such as false trust reporting or compromised attacks, where trust-based routing to defend these attacks is more difficult because of their ambiguous behavior. In order to ensure data transmission reliability even against such attacks, in this letter, a centralized trust based secure routing (CSR) scheme is proposed for wireless networks. Simulation results show that the CSR scheme provides better performance compared to the active trust routing and shortest path routing schemes.
IoT (IoT) networks generate massive amounts of data while supporting various applications, where the security and protection of IoT data are very important. In particular, blockchain technology ...supporting IoT networks is considered as the most secure, expandable, and scalable database storage solution. However, existing blockchain systems have scalability problems due to low throughput and high resource consumption, and security problems due to malicious attacks. Several studies have proposed blockchain technologies that can improve the scalability or the security level, but there have been few studies that improve both at the same time. In addition, most existing studies do not consider malicious attack scenarios in the consensus process, which deteriorates the blockchain security level. In order to solve the scalability and security problems simultaneously, this paper proposes a Dueling Double Deep-Q-network with Prioritized experience replay (D3P) based secure trust-based delegated consensus blockchain (TDCB-D3P) scheme that optimizes the blockchain performance by applying deep reinforcement learning (DRL) technology. The TDCB-D3P scheme uses a trust system with a delegated consensus algorithm to ensure the security level and reduce computing costs. In addition, DRL is used to compute the optimum blockchain parameters under the dynamic network state and maximize the transactions per second (TPS) performance and security level. The simulation results show that the TDCB-D3P scheme can provide a superior TPS and resource consumption performance. Furthermore, in blockchain networks with malicious nodes, the simulation results show that the proposed scheme significantly improves the security level when compared to existing blockchain schemes by effectively reducing the influence of malicious nodes.
With the emergence of new types of real-time network cameras, the demand for video streaming services is rapidly growing. To cope with this growing demand, the Moving Picture Experts Group (MPEG) has ...established a standard under the name Dynamic Adaptive Streaming over HTTP (DASH). MPEG-DASH adjusts the resolution to provide seamless audio and video streaming. However, in disaster situations, it is difficult to understand the accident situation using low-resolution videos. RNC-DASH is proposed as an optimization technique that continuously provides images with a certain resolution or higher. In disaster area surveillance, RNC-DASH helps accurate situational awareness (SA) and rapid response by receiving highresolution images.
Blockchain technology has been developed for cryptocurrency systems. Bitcoin, the most famous cryptocurrency type, guarantees a safe consensus using the Proof of Work (PoW) process. The PoW scheme is ...currently operating as a basic consensus algorithm for blockchain systems that are used widely in various industries. However, the PoW algorithm lacks in support of mathematical analysis, which hinders discoveries of potential weaknesses and flaws in the blockchain system. Therefore, in this paper, the correlation between the key parameters (i.e., TPS, difficulty, miners) in a blockchain system are analyzed based on mathematical analysis.
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