The main objective of this dissertation is to analyze and improve the handover (HO) performance in the current and future cellular networks, such as 4G, 5G, and B5G. In this dissertation, it was found that the legacy downlink handover (DL-HO) procedure for both LTE (4G) and NR (5G) is underperforming for future ultra-dense networks because of high measurement report signaling, and high HO failure rate due to delay in the measurement report delivery.
This dissertation provides an uplink handover (UL-HO) solution to cope with the problems of existing DL-HO. Using the proposed UL-HO scheme, the measurement report signaling transmission/reception is not required, eliminating the aforementioned issues in the DL-HO. In this way, the UL-HO procedure completes before the user equipment loses its connection with the serving base station, reducing HO rate, HO failures, and, most importantly, user equipment and base station power consumption due to the reduction in HO signaling. Moreover, this work extends the applicability of the UL-HO scheme for the mobile small cell (MSC) to eliminate the measurement report signaling during MSC HO to the donor base station. Therefore the HO delay can be reduced, decreasing the chances of single point of failures (in case of group mobility) and thus, uninterrupted services can be provided to on-board users.
The proposed UL-HO scheme can be applied to the future cellular network generations heading towards small-cell networks operating at higher frequencies and implementing a user-centric no-cell approach (UCNC). In addition, future open radio access network (O-RAN) standard specifications target an RAN architecture based on a softwarized radio resource management platform of functions including power-efficient HO as herewith proposed. Furthermore, it is anticipated that the current static integrated access and backhaul nodes will evolve into mobile nodes in future 3rd generation partnership project (3GPP) releases, thus enabling the MCS concept. The proposed UL-HO scheme is very effective for MSCs deployments as it can reduce the MSC HO failures to the donor base station.
The proposed UL-HO solutions are being currently studied in 3GPP standardization as an alternative solution for DL-HO. The simulation analysis in this work confirms that the UL-HO scheme is an excellent candidate for an energy-efficient HO procedure in future releases of the 3GPP standards.
Opponents: Professor Erik G. Larsson, Linköping University, Sweden and Professor Sergey Andreev, Tampere University, Finland
Custos: Professor Riku Jäntti, Aalto University School of Electrical Engineering, Department of Communications Engineering
Contact information of the doctoral candidate: Muhammad Tayyab, [email protected], +358 40 5289 605
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