Cognitive Wireless Sensor Network Platform for Cooperative Communications

Nowadays, Wireless Ad Hoc Sensor Networks (WAHSNs), specially limited in energy and resources, are subject to development constraints and difficulties such as the increasing RF spectrum saturation at the unlicensed bands. Cognitive Wireless Sensor Networks (CWSNs), leaning on a cooperative communication model, develop new strategies to mitigate the inefficient use of the spectrum that WAHSNs face. However, few and poorly featured platforms allow their study due to their early research stage. This paper presents a versatile platform that brings together cognitive properties into WAHSNs. It combines hardware and software modules as an entire instrument to investigate CWSNs. The hardware fits WAHSN requirements in terms of size, cost, features, and energy. It allows communication over three different RF bands, becoming the only cognitive platform for WAHSNs with this capability. In addition, its modular and scalable design is widely adaptable to almost any WAHSN application. Significant features such as radio interface (RI) agility or energy consumption have been proven throughout different performance tests. 1. Introduction According to the CISCO report [1], ubiquitous computing is shown as one of the most important trends with a 40-fold increase between 2010 and 2015. Typical ubiquitous applications include security and surveillance, automatic monitoring of forest fires, avalanches, hurricanes, health or vehicular networks. WAHSNs provide a technological solution to these challenges, so their growth is closely linked to these data. This increasing demand for wireless communication presents a challenge to efficient spectrum utilization and spectral coexistence. Regarding spectrum scarcity, most WAHSN solutions operate on unlicensed frequency bands. In general, they use the industrial, scientific, and medical (ISM) bands like the 2.4？GHz band also used by Wi-Fi or IEEE 802.15.4 devices. For this reason, the unlicensed spectrum bands are becoming overcrowded [2]. To address this challenge, new techniques arise to be applied in WAHSNs, such as Cognitive Radio (CR) [3]. CR enables opportunistic access to the spectrum through cooperation and context awareness. Spectrum sensing capabilities and cooperation between devices allow for better spectrum use and better data reliability. The concept of CN was proposed as a wireless network that is aware of its environment and adapts its internal values, thanks to cooperation, to achieve reliable and efficient communication. CN has three main technical components: cognitive capabilities of devices, collaboration among