Key challenges, drivers and solutions for mobility management in 5G networks: a survey

Ensuring a seamless connection during the mobility of various User Equipments (UEs) will be one of the major challenges facing the practical implementation of the Fifth Generation (5G) networks and beyond. Several key determinants will significantly contribute to numerous mobility challenges. One of the most important determinants is the use of millimeter waves (mm-waves) as it is characterized by high path loss. The inclusion of various types of small coverage Base Stations (BSs), such as Picocell, Femtocell and drone-based BSs is another challenge. Other issues include the use of Dual Connectivity (DC), Carrier Aggregation (CA), the massive growth of mobiles connections, network diversity, the emergence of connected drones (as BS or UE), ultra-dense network, inefficient optimization processes, central optimization operations, partial optimization, complex relation in optimization operations, and the use of inefficient handover decision algorithms. The relationship between these processes and diverse wireless technologies can cause growing concerns in relation to handover associated with mobility. The risk becomes critical with high mobility speed scenarios. Therefore, mobility issues and their determinants must be efficiently addressed. This paper aims to provide an overview of mobility management in 5G networks. The work examines key factors that will significantly contribute to the increase of mobility issues. Furthermore, the innovative, advanced, efficient, and smart handover techniques that have been introduced in 5G networks are discussed. The study also highlights the main challenges facing UEs' mobility as well as future research directions on mobility management in 5G networks and beyond

Rain Rate and Rain Attenuation Over Millimeter Waves in Tropical Regions Based on Real Measurements

Rain attenuation is one of the major issues facing the propagation of electromagnetic waves in the Fifth Generation (5G) networks. The case becomes worse with the millimeter-wave (mmW) bands as they are characterized by small waveform and high path loss. The close physical size of the raindrops with the wavelength of the mmW bands leads to severe degradation in the received signal strength. Thus, this paper studies the impact of rain rate and rain attenuation on the 38 GHz communication link. The study conducted based on real measurement data collected in a tropical region (Malaysia) for continuously one year. The annual analyzed results show a noticeable impact caused by the rain. It is observed that at 0.01 percentage of the time the average annual rain rate is 119 mm/hr. Regarding the rain attenuation, it has been observed that the horizontal polarization (HP) is affected by the rain more than the vertical polarization (VP). The specific rain attenuation of the measured data is 15 dB and 18 dB for VP and HP at 38 GHz, respectively