Safe Regions for Moving Reverse Neighbourhood Queries in a Peer-to-Peer Environment

The peer-to-peer (P2P) paradigm has become very popular for storing and sharing information. In most P2P systems, peers are connected by means of a limited range of uniform networks, leading to issues when some connected peers are isolated from the others. In order to address such issues, isolated peers rely on devices with long-range networks to relay their messages. However, since long-range devices can move freely, the set of connected peers may lose their connection. Hence, it is important not only to identify, but also to maximise the area known as the safe region (SR) where a long-range device can move freely while still maintaining connection with its peers. This paper illustrates an innovative and generic monitoring framework that addresses the issues related to frequent query location updating using a systematic approach. In our approach, we propose to apply the Reverse Nearest Neighbourhood (RNNH) concept in a P2P environment to efficiently identify and maximise the irregularly shaped area of the SR up to four times for the potential movement of the long-range devices. It was found that there is no need for costly re- computation when the query is retained within the SR. Monte-Carlo simulation was performed to calculate the area of the SR by weighing in shape irregularity. Experimental results demonstrate the effectiveness and efficiency of our approach.