In this paper, the authors present an original approach to reduce energy consumption in an IEEE 802.15.4/ZigBee cluster tree network related to a backbone network. Their approach uses an enhanced mobility management of end devices combined with a rate adaptation algorithm. The mobility management approach anticipates link disruption and relies on a speculative algorithm that does not require scanning neighbor cells. The joint mobility management and rate adaptation methods are based on the Link Quality Indicator (LQI). It is demonstrated that even in a noisy environment, the energy consumption as well as the latency of mobile devices can be significantly reduced.