A cross layer design and evaluation of IEEE 802.15.4 network with an enhanced sensor gateway: Injecting hierarchy into wireless sensor networks

We propose an enhanced IEEE 802.15.4 gateway for use in a hierarchical network architecture. We perform a system comparison between it and a gateway using a normal sensor mote. This comparison includes a PHY and MAC simulation benefiting from ray trace propagation modeling of a large office building. The proposed enhanced gateway offers a 21.2 dB improvement in receiver sensitivity and an ideal channel equaliser. We analyze these benefits before performing a full system simulation. We report improvements over a classical sensor gateway in all key areas of packet delivery, latency and mote energy efficiency. Just under a six-fold increase in indoors range is also reported. We observe a reduction in performance due to channel distortion and combat it by proposing a fractionally spaced equaliser. We show that for buildings with large RMS delay spreads - greater than 100ns (e.g. conference centres), significant benefit may be derived.