Wireless communications are in general more energy-consuming than wired ones because of the effects of path loss and fading. However, it is well-known that multihop techniques are effective for reducing the path loss cost, while large antenna arrays can increase the diversity gain. Hence, a joint-optimization of the number of hops and the antenna array size would provide a useful scheme for designing energyconstrained wireless applications. In this work we study this joint-optimization in the

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... ntext of low-power wireless networks, focusing on the antenna selection scheme. Results show that, regardless of their high power consumption, receive antenna arrays of more than 60 elements are optimal for long-range communications (more than 150 meters) from the point of view of the overall energy budget. In contrast, using a single transmit antenna is the best choice due to the channel estimation cost. Results also show that the energy consumption of optimized systems with large receive antenna arrays can be up to 3.4 times smaller than the consumption of single antenna multihop systems. Therefore, systems with large antenna arrays can be attractive for reducing the traffic in crowded energyconstrained wireless networks, as they can be more energyefficient using less but longer hops than single-antenna systems.