Decentralized Consensus for Edge-Centric Internet of Things: A Review, Taxonomy, and Research Issues

TLDR

The rapid growth of IoT devices has driven a shift toward edge‑centric computing, which offers higher bandwidth, lower latency, and better connectivity than legacy cloud‑centric platforms, and technologies such as fog and mist computing provide distributed, decentralized solutions to mitigate cloud drawbacks. This review aims to fill the gap in comprehensive analyses of decentralized consensus systems for edge‑centric IoT by scrutinizing their pros and cons and proposing a thematic taxonomy. The authors conduct an extensive literature review and qualitative analysis, categorizing existing consensus systems and evaluating their key features, commonalities, and differences based on derived criteria. The paper identifies several open research issues for decentralized consensus in edge‑centric IoT, highlighting centralization risks and deficiencies in both blockchain and blockchain‑less solutions.

Abstract

With the exponential rise in the number of devices, the Internet of Things (IoT) is geared toward edge-centric computing to offer high bandwidth, low latency, and improved connectivity. In contrast, legacy cloud-centric platforms offer deteriorated bandwidth and connectivity that affect the quality of service. Edge-centric Internet of Things-based technologies, such as fog and mist computing, offer distributed and decentralized solutions to resolve the drawbacks of cloud-centric models. However, to foster distributed edge-centric models, a decentralized consensus system is necessary to incentivize all participants to share their edge resources. This paper is motivated by the shortage of comprehensive reviews on decentralized consensus systems for edge-centric Internet of Things that elucidates myriad of consensus facets, such as data structure, scalable consensus ledgers, and transaction models. Decentralized consensus systems adopt either blockchain or blockchainless directed acyclic graph technologies, which serve as immutable public ledgers for transactions. This paper scrutinizes the pros and cons of state-of-the-art decentralized consensus systems. With an extensive literature review and categorization based on existing decentralized consensus systems, we propose a thematic taxonomy. The pivotal features and characteristics associated with existing decentralized consensus systems are analyzed via a comprehensive qualitative investigation. The commonalities and variances among these systems are analyzed using key criteria derived from the presented literature. Finally, several open research issues on decentralized consensus for edge-centric IoT are presented, which should be highlighted regarding centralization risk and deficiencies in blockchain/blockchainless solutions.