Resource allocation for heterogeneous radio-frequency and visible-light networks

Abstract

In recent years, mobile data traffic demands have been increased exponentially, and the conventional cellular systems can no longer support the capacity demands. A potential solution for meeting such demands may be Heterogeneous Network (HetNet) techniques. A HetNet may integrate diverse radio access technologies (RAT) such as UMTS Terrestrial Radio Access Networks (UTRAN), GSM/EDGE Radio Access and Network (GERAN), Wireless Local Area Network (WLAN) as well as possibly Visible Light Communication (VLC) networks. The improved channel gain of the HetNet techniques is achieved by employing the small cells and by reduced transmission distance. However, the deployment of HetNet techniques also impose several technical challenges, for example the interference management, handovers, resource management and modelling of HetNets.

A HetNet relies on multiple types of access nodes in a wireless network. These access nodes can use either the same technology or different technologies. When the access nodes employ the same technology and use the same frequency band, a major problem is the Co-Channel-Interference (CCI) between these access nodes. We firstly investigate a Radio-Frequency (RF) based HetNet in Chapter 3, which is constituted by the macrocells and the femtocells. More explicitly, the impacts of femtocells on traditional macrocells are studied, when the macrocells are relying on Fractional Frequency Reuse (FFR). The design, performance analysis and optimization problems of this FFR aided two-tier HetNet is investigated. We found the advantage of FFR eroded in dense femtocell scenarios and the optimized network tends to become a Unity Frequency Reuse (UFR) aided system. In order to mitigate the cross-tier interference, we proposed a statics spectrum allocation scheme, namely Swapping Spectrum Access (SSA). Both the Outage Probability (OP) of femtocell Mobile Terminals (MTs) in cell centre region and that of the macrocell MTs in the cell edge region is reduced by the proposed SSA. The optimized network using our SSA is more robust to the detrimental impact of femtocells.

Another constitution of a HetNet may rely on integrating different technologies of wireless communication networks. We focus on our attentions on a HetNet composing by a RF femtocell and a VLC network in Chapter 4 and 5. An important component of this architecture is its Resource Management (RM). We investigate the Resource Allocation (RA) problems, under the diverse quality of service (QoS) requirements in terms of data rate, fairness and the statistical delay requirements. Two types of MTs, multi-homing MTs and multi-mode MTs are considered, where multi-homing MTs have the capability of aggregating resources from different networks, while the multi-mode MTs always select a single network for their connection. We proposed a sub-optimal decentralized method for solving the RA problems of both the multi-homing MTs and multi-mode MTs. The simulation results confirm the conceived method is capable of satisfying the QoS requirements. Furthermore, we employ more sophisticated transmission strategies for the VLC network and study their performance in Chapter 5. Again, the RA problems of the HetNet relying on different transmission strategies are investigated.

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Identifiers

ORCID for Lajos Hanzo: orcid.org/0000-0002-2636-5214

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