Wireless Sensor Networks (WSNs) are being considered for a wide range of applications, however, they still face various challenges, e.g. short communication range and the hidden terminal problem, to name a couple. In this paper, we build up on our previous work in [1], present a WSN prototype that demonstrates this solution, and analyze its performance in different indoor conditions by measurement and simulation. The measurement study explores radio propagation, transmission efficiency and deployment of the proposed extended-range WSN. The simulations are performed for a large scale WSN, taking into account indoor propagation, enhanced 802.15.4 PHY and MAC models and sensor application. The measurements demonstrate the feasibility and performance of the first generation extended-range 802.15.4 WSN, while the simulation study shows the network performance and scalability in terms of transmission efficiency and energy cost.

In modern wireless communication systems, it is very important to realize simultaneously high-efficiency and linear operation of power amplifiers. This paper-overview describes the historical aspect of the Doherty approach to the power-amplifier design introduced in 1936 and modern trends in Doherty amplifier (DA) design techniques using multistage and asymmetric multiway architectures. To increase efficiency over the power backoff range, the switchmode class-E, conventional class-F, or inverse class-F operation mode by controlling the second and third harmonics can be used in the load network. The DA with a series-connected load, and inverted, push–pull, balanced, and parallel Doherty architectures are also described and discussed. Finally, examples of the lumped DA implemented in monolithic microwave integrated circuits, digitally driven Doherty technique, and broadband capability of the two-stage DA are given.