Pre-Grant Signaling for Energy-Efficient 5G and Beyond Mobile Devices: Method and Analysis

Due to the severely limited battery capacities, the energy efficiency of mobile devices plays an important role in their usability. In general, the cellular subsystem is one of the major contributors to the energy consumption of a mobile device, thus improving its energy efficiency is of paramount importance. In this paper, a new concept of pre-grant message together with associated control plane signaling is introduced, aiming to reduce the energy consumption of the cellular subsystem in the downlink, without notable increase in the buffering delay or latency. The proposed method is fully independent of the ordinary discontinuous reception (DRX) principle, which means that both methods can co-exist and act together to efficiently reduce the energy consumption of the user equipment. The performance of the proposed scheme in terms of the false alarm and misdetection rates are investigated and evaluated, in both additive white Gaussian noise and Rayleigh fading channels. The obtained numerical results show that the pre-grant message signaling can be decoded very reliably and can reduce the system power consumption, relative to an ordinary DRX-only reference system, by up to 70%, 68%, and 62% for FTP traffic, video streaming and VoIP, respectively, at the cost of negligible increase in the signaling overhead. The proposed method is also compared in terms of the energy consumption and energy efficiency against another state-of-the-art power-saving mechanism, namely the wake-up radio-based approach. The obtained results show that the pre-grant approach outperforms the wake-up-based system under broad range of traffic characteristics.