Cache-based transport protocols in wireless sensor networks: A survey and future directions

Sensor nodes in Wireless Sensor Networks (WSNs) are battery-powered devices that consume energy during data transmission and processing. One of the most critical tasks in a sensor network is dealing with reliable end-to-end transmissions and optimizing the power consumption. WSNs are error prone due to the constrained nature of the nodes and the interference with other wireless technologies such as Wifi and Bluetooth. One possible way to minimize this problem is caching the data. Data caching is one technique of improving the performance of a transport protocol. Since a typical data transmission consumes more energy than processing in a sensor network, the use of caching enables quick access to data. Therefore, caching, if used efficiently, could reduce overall network traffic and hence bandwidth can be optimally utilized. Unfortunately, a systematic analysis of caching in WSNs was until now lacking. Given that WSNs are expected to play an important role in Machine Type Communications (MTC) and Internet of Things (IoT), the authors believe that now is time to collect the results of years of research on this important topic. This paper presents a comprehensive survey on the state-of-the-art cache-based transport protocols in wireless sensor networks. We classify the transport protocols by presenting a thematic taxonomy of the current cache management mechanisms in wireless sensor networks. Moreover, the critical aspects of the existing cache-ware schemes in sensor networks are analyzed to determine the strengths and weaknesses of such protocols. The similarities and differences of the transport protocols based on the important parameters, such as cache insertion/replacement policy, cache size requirement, cache location, cache partition, and cache decision are investigated in this paper. In addition to that, we discuss open research issues and challenges of cache-based transport protocols in wireless sensor networks. We strongly believe that this study can serve as a basis so that future implementations can choose the combination of caching mechanisms that best fits their target application scenario.