We study the benefits of electronically-switched directional (ESD) antennas in wireless sensor networks (WSNs). ESD antennas have proved beneficial in cellular and ad-hoc networks, by increasing the communication range and by alleviating contention in directions other than the destination. The advantages in WSNs are, however, still largely to be quantified. Unlike existing works in this field, we start by characterizing a real-world antenna prototype, and apply this to an existing WSN stack, which we adapt with minimal changes. Our results show that: i) the combination of a low-cost ESD antenna and a mainstream WSN stack already brings significant performance improvements, e.g., nearly halving the radio-on time per delivered packet; ii) the margin of improvement available to alternative clean-slate protocol designs is similarly large and concentrated in the control rather than the data plane; iii) by artificially modifying our antenna's link-layer model, further potential benefits opened by different antenna designs may be available. To the best of our knowledge, this is the first study providing such quantitative insights based on a real ESD antenna prototype and a complete WSN stack.
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