On the improvement of wireless mesh sensor network performance under hidden terminal problems

摘要

Wireless Mesh Sensor Networks (WMSNs) have recently received a great deal of attention in the scientific and developers communities due to the significant advances of this technology in the wireless communication field. The main reason was that competing WMSN approaches that emerged in the last few years provide mesh capabilities (e.g., robustness, scalability, multi-hop mesh routing, or energy efficiency, among others) to conventional WSN-based applications, encouraging researchers and end users to adopt new perspectives and solutions. Unfortunately, each one of these approaches lacks some (or many) of the aforementioned mesh capabilities, not assuring, a priori, the feasibility and, especially, the long-term stability of WMSN applications. The IEEE 802.15.5 standard and, in particular, its Asynchronous Energy Saving (ASES) mode was conceived to fill this gap since it integrates, in a single solution, most of these capabilities, guaranteeing, among other benefits, a long network lifetime. However, the ASES mode has no built-in mechanisms to mitigate the negative effects of hidden terminals, which sharply degrades the network performance. This fact leads us to conclude that any current WMSN approach is non-exempt of some problem, which prevents the definitive boost of this technology in the consumer market. Under these circumstances, our contribution to the WMSN field in this paper is a twofold proposal addressed to alleviating the hidden terminal problems in a scenario running under the most relevant design premises of ASES mode. Therefore, we first formulate a multi-objective optimization and then solve it by using Goal Programming. Both mathematical techniques are applied to obtain the best solution that simultaneously minimizes the aggregate message collision time due to hidden terminals and maximizes the network lifetime. Secondly, we propose the design of a MULti-channel Time-scheduled algorithm for the Hidden Terminal problem avoidance (MULTI-HIT) which appropriately exploits the available bandwidth and accomplishes a straightforward coordination between any sender-receiver pair. Finally, the analysis and simulation experiments are presented and their results carefully discussed, demonstrating the effectiveness of both proposals in the WMSN arena.