DAG-based blockchains face the key challenge of transaction inclusion collision due to the high concurrency and network delay. In this paper, we propose “We-TIPS”, a weak-block-based transaction inclusion protocol with signaling, designed to tackle this key challenge. In We-TIPS, during the mining process, the miner can broadcast the weak block header as a signal, which can indicate the miner’s current transaction inclusion. With the prompt broadcast of the signal, the miner can effectively avoid the transaction inclusion collision and thus greatly boost the system performance. Besides, we develop a transaction inclusion game in We-TIPS to model miners’ interaction and show that it is a potential game. We propose a decentralized transaction inclusion algorithm that can achieve the approximate Nash equilibrium. Finally, we conduct intensive experiments to demonstrate the superior performance of We-TIPS.

In this paper, we propose a novel and energy-efficient blockchain system, CrowdMine, which exploits useful crowdsourcing computation to achieve decentralized consensus. CrowdMine solves user-proposed computing tasks and utilizes the computation committed to the task solving process to secure decentralized on-chain storage. With our designed “Proof of Crowdsourcing Work” (PoCW) protocol, our system provides an efficient paradigm for computation and storage in a trustless and decentralized environment. We also implement the system with 40 distributed nodes to demonstrate its performance and robustness.

DAG-based blockchain faces the key challenge of transaction inclusion collision due to the high concurrency and network delay. In this paper, we propose “We-TIPS”, the weak-block-based transaction inclusion protocol with signaling to tackle this key challenge. In We-TIPS, during the mining process, the miner can broadcast their weak block header as a signal, which can indicate the miner's current transaction inclusion. With the prompt broadcast of the signal, the miner can effectively avoid the transaction inclusion collision and thus greatly boost the system performance. Besides, we develop a transaction inclusion game in We-TIPS to model miners' interaction and further show that it is a potential game. We propose a decentralized transaction inclusion algorithm that can achieve the approximate Nash equilibrium. Finally, we conduct intensive experiments to demonstrate the superior performance of the We-TIPS.

Payment Channel Network (PCN) is proposed as a promising layer-two solution to tackle the scalability problem of current blockchain systems, which allows the two transacting parties to perform off-chain transactions through their established payment channel. For the transacting parties who are not directly connected, PCN allows them to route the transaction through some intermediate nodes with sufficient balance. Designing an efficient routing protocol is one of the most important and challenging problems in improving the performance of PCN. To tackle this challenge, we propose Real-Time Recursive Routing (RTRR), an efficient routing algorithm that can achieve a short routing time with strong privacy protection and high flexibility in the dynamic scenario. In addition, we investigate the bidding process in RTRR and derive the equilibrium strategy, which implies that the proposed protocol prefers to route the transaction through the nodes with a higher success rate, contributing to a better performance. Both the theoretical analyses and the empirical experiment results demonstrate the high efficiency of RTRR.

Directed Acyclic Graph (DAG) is a popular approach to achieve scalability of blockchain networks. Due to its high efficiency in data communication and great scalability, DAG has been widely adopted in many applications such as Internet of Things (IoT) and Decentralized Finance (DeFi). DAG-based blockchain, nevertheless, faces the key challenge of transaction inclusion collision due to the high concurrency and the network delay. Particularly, the transaction inclusion collision in DAG-based blockchain leads to the revenue and throughput dilemmas, which would greatly degrade the system performance. In this paper, we propose “TIPS”, the Transaction Inclusion Protocol with Signaling, which broadcasts a signal indicating the transactions in the block. We show that with the prompt broadcast of a signal, TIPS substantially reduces the transaction collision and thus resolves these dilemmas. Moreover, we show that TIPS can defend against both the denial-of-service and the delay-of-service attacks. We also conduct intensive experiments to demonstrate the superior performance of the proposed protocol.

Sharding is one of the most promising and practical methods to achieve horizontal scalability of blockchain networks. However, the increasing number of cross-shard transactions in blockchain sharding protocols may degrade the system throughput. In this paper, we investigate how to distribute users properly in the shard-based blockchains to boost the system transaction performance. We first build an open Jackson queueing network model to capture users' transaction dynamics on shards. Then we cast users' interactions as a shard-based blockchain game, wherein each user aims to minimize its transaction confirmation time and transaction fee. We investigate the equilibrium of the game, and design a polynomial-time algorithm to find efficient equilibria with good system performance. We further design a novel sharding protocol with dynamic user distribution for the permissionless blockchain, and the protocol can maintain good performance in long-term dynamic environment. Extensive numerical results using realistic blockchain transaction data demonstrate that the proposed algorithm and the designed protocol can achieve superior performance for shard-based blockchains.