# A Survey on Data Storage and Information Discovery in the WSANs-Based Edge Computing Systems
###### Abstract  
In the post-Cloud era, the proliferation of Internet of Things (IoT) has pushed the horizon of Edge computing, which is a new computing paradigm with data processed at the edge of the network. As the important systems of Edge computing, wireless sensor and actuator networks (WSANs) play an important role in collecting and processing the sensing data from the surrounding environment as well as taking actions on the events happening in the environment. In WSANs, in-network data storage and information discovery schemes with high energy efficiency, high load balance and low latency are needed because of the limited resources of the sensor nodes and the real-time requirement of some specific applications, such as putting out a big fire in a forest. In this article, the existing schemes of WSANs on data storage and information discovery are surveyed with detailed analysis on their advancements and shortcomings, and possible solutions are proposed on how to achieve high efficiency, good load balance, and perfect real-time performances at the same time, hoping that it can provide a good reference for the future research of the WSANs-based Edge computing systems. Internet of Things; Edge computing; WSANs; data storage; information discovery 16 January 201816 January 201 while the actuators are responsible for taking actions on the events happening in the monitored field as well as processing and storing the data collected by the sensor nodes. Generally speaking, the actuators have much more resources, such as the storage space and the energy, much stronger computation capability and longer communication radius than the sensor nodes. Thus, protocols and schemes should be designed specifically for WSANs rather than immigrating them directly from WSNs. In this paper, we focus on the data storage and information discovery technologies, which are the core technologies of the WSANs-based Edge computing systems, in WSANs and conduct a survey of the existing related schemes. In summary, the main contributions of this paper are listed as follows:  
1. We first summarize the data-storage and information-discovery schemes proposed for WSNs, and analyze why those schemes are not fit for the WSANs-based Edge computing systems. We do this because there are many similarities between the WSANs-based Edge computing systems and the WSNs-based systems. 2. The existing schemes proposed for WSANs on data storage and information discovery are surveyed and compared with each other, and detail analysis on their advancements and shortcomings is also presented. 3. Possible solutions are given on how to achieve high efficiency, high load balance, and perfect real-time performances at the same time for data storage and information discovery in the WSANs-based Edge computing systems. The remainder of this paper is organized as follows: in Section 2, we summarize the existing related schemes for WSNs, and analyze why they are not fit for the WSANs-based Edge computing systems. In Section 3, we survey the schemes on data storage and information discovery proposed for WSANs, and discuss their advancements and shortcomings. In Section 4, possible solutions to achieving the aforementioned multi-objectives in the WSANs-based Edge computing systems are proposed. In Section 5, we conclude the paper. Analyzing Whether the Data-Storage and Information-Discovery Schemes Proposed for WSNs Fit for WSANs  
Before surveying the data-storage and information-discovery schemes for the WSANs-based Edge computing systems, we first categorize schemes proposed for WSNs because there are many commonalities between WSNs and WSANs. In WSNs, the problem of data storage and information discovery has been studied for many years.