Directional Discontinuous Reception (DDRX) for mmWave Enabled 5G Communications

Emerging mmWave enabled 5G wireless communications, offer tremendous increase in data demands and better quality expectations. However, high mmWave frequencies call for directional beamforming to overcome propagation limitations and enhance spatial capabilities. The establishment of new directional paradigm challenges the current Discontinuous Reception (DRX) mechanism for power saving in the User Equipment (UE). In this article, we introduce new Directional-Discontinuous Reception (DDRX) for directional air interface expected in mmWave enabled 5G communications. DDRX mechanism emphasizes the importance of beam searching for alignment of directional beams between UE and 5G base station (gNB), after every sleep cycle. Beam searching, though inevitable, reduces the effective sleep time. We propose three new DDRX mechanisms: Integrated DDRX (I-DDRX), Standalone DDRX (S-DDRX), and Cooperative DDRX (C-DDRX) to limit the impediments on power saving. Probabilistic estimation of UE's power saving and delay is performed for all the three different DDRX mechanisms using semi-Markov process. The power saving achieved in I-DDRX is 12.1 percent higher than S-DDRX. The power saving of C-DDRX is 6.1 percent higher than S-DDRX. Analytical results of DDRX proposals are validated by simulation studies, performed over real wireless trace.