Supervisors info:
Άννα Τζανακάκη, Επίκουρη Καθηγήτρια, Τμήμα Φυσικής, ΕΚΠΑ
Δημήτριος Φραντζεσκάκης, Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Έκτορας Νισταζάκης, Αναπληρωτής Καθηγητής, Τμήμα Φυσικής, ΕΚΠΑ
Summary:
The demanding requirements of 5G and vertical operational and end-user services including unprecedented level of scalability (x1000) on the numbers of interconnected elements, high bandwidth, low latency and ubiquitous coverage, introduce the need for a common, flexible and open underlying network infrastructure involving a variety of advanced interconnected radio access network technologies. To address the limitations of current Radio Access Networks (RANs), Cloud-RANs (C-RANs) have been proposed introducing increased transport bandwidth requirements and imposing strict latency and synchronization constraints. To relax the stringent C-RAN requirements, taking advantage of its pooling and coordination gains the adoption of alternative architectures exploiting the option of flexible functional splits has been proposed. The concept of flexible splits relies on transferring some of the processing functions away from the RU and locating these centrally at a CU.
In this master thesis, the concept of flexible functional splits is addressed by appropriately combining servers with low processing power (cloudlets) and relatively large-scale DCs placed in the access and metro domains respectively. The remote processing requirements associated with some of the functional split options, impose the need for a high bandwidth transport interconnecting RUs and the CU. On the other hand, the variability of remote processing requirements across the various split options introduce the need for a transport network that offers finely granular and elastic resource allocation capabilities. The selection of the optimal split option is performed in a dynamic fashion through a novel mathematical model based on Evolutionary Game Theory (EGT). This model allows network operators to dynamically adjust their FH split option with the objective to unilaterally minimize their operational expenditures in terms of power consumption. The speed of convergence and the stability of the proposed scheme is theoretically analyzed for different scenarios and use cases. Finally, the impact of various parameters characterizing the 5G network (i.e. bandwidth, cost transmission, power consumption etc) on the split option selection is analytically determined.
In Chapter 2, the Fifth-Generation key enablers- the Densification and the Centralization of Baseband processing -are presented. Chapter 3 introduces the notion of Flexible Centralization of Wireless Networks. Five possible functional splits are analyzed and the required data rate for each split is calculated. In Chapter 4, a model for calculating the power consumption of the base station, as well as the network’s power consumption is discussed. In Chapter 5, we examine the Evolutionary Game Theory, which we will use as a mathematical tool in order to approach this problem. Chapter 6 implements the replicator equation of evolutionary game theory, in order to find the optimal split. Lastly, in Chapter 7 we examine the optimal split’s dependence on the system parameters, with the usage of numerical examples.
Keywords:
C-RAN, Cloud, Functional Splits, Evolutionary Game Theory, Replicator Equation
