www.kips.or.kr Copyright© 2017 KIPS A Survey on Asynchronous Quorum-Based Power Saving Protocols in Multi-Hop Networks Mehdi Imani*, Majid Joudaki**, Hamid R. Arabnia***, and Niloofar Mazhari**** Abstract Quorum-based algorithms are widely used for solving several problems in mobile ad hoc networks (MANET) and wireless sensor networks (WSN). Several quorum-based protocols are proposed for multi-hop ad hoc networks that each one has its pros and cons. Quorum-based protocol (QEC or QPS) is the first study in the asynchronous sleep scheduling protocols. At the time, most of the proposed protocols were non-adaptive ones. But nowadays, adaptive quorum-based protocols have gained increasing attention, because we need protocols which can change their quorum size adaptively with network conditions. In this paper, we first introduce the most popular quorum systems and explain quorum system properties and its performance criteria. Then, we present a comparative and comprehensive survey of the non-adaptive and adaptive quorum-based protocols which are subsequently discussed in depth. We also present the comparison of different quorum systems in terms of the expected quorum overlap size (EQOS) and active ratio. Finally, we summarize the pros and cons of current adaptive and non-adaptive quorum-based protocols. Keywords Ad Hoc Networks, Asynchronous Sleep Scheduling Protocols, Power Saving Protocols, Quorum Based Systems 1. Introduction A quorum system is sets of quorums; which any two quorums at least have an intersection. Quorum- based algorithms are widely used to solve several problems like: replica control [1-4], mutual exclusion [5,6], location management [7-10], information dissemination [11,12] and data aggregation [13] in mobile ad hoc networks (MANETs) or wireless sensor networks (WSNs). In all quorum-based protocols (QBP), time is divided into periods called quorum interval (QI) which each QI contains n equal time units called beacon interval (BI). During each BI, a node can stay awake or switch to sleep mode. A quorum system determines a cyclic pattern, that defines the sleep/wakeup scheduling during  BIs ( is an integer), we call  the system size. The advantage of QBP is that a node just needs to be awake √  BIs in every  BIs. In QBP, we can guarantee that every two nodes have intersection at least in one awake BI. In [14] and [15] some methods have been proposed in which the quorum systems are considered the ※ This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Manuscript received September 5, 2017; accepted October 14, 2017. Corresponding Author: Mehdi Imani (m.imani@gmail.com) * Dept. of Electrical and Computer Engineering, Faculty of Shahid Beheshti, Alborz Branch, Technical and Vocational University (TVU), Alborz, Iran (m.imani@gmail.com) ** Islamic Azad University, Doroud branch, Doroud, Iran (m.joudaki@gmail.com) *** Dept. of Computer Science, University of Georgia, Athens, Georgia, USA (hra@cs.uga.edu) **** Dept. of Computer Science, Allameh Dehkhoda University, Qazvin, Iran (nl.mazhari@gmail.com) J Inf Process Syst, Vol.13, No.6, pp.1436~1458, December 2017 ISSN 1976-913X (Print) https://doi.org/10.3745/JIPS.03.0082 ISSN 2092-805X (Electronic) INVITED PAPER