Network Function Virtualization In Fog Networks

The network function virtualization (NFV) paradigm uses commodity servers to implement \u27\u27softwarized networking capabilities and replace costly, proprietary hardware systems. In particular a wide range of virtual network function (VNF) tasks can be implemented here, including rewalls, load-balancers, encryption engines, address translation devices, domain name servers, even routers and switches. NFV also enables a high-degree of service exibility, allowing operators to interconnect multiple VNFs to build highly-customized service function chain (SFC) sequences for their clients. As a result these related technologies are gaining widespread traction in enterprise and cloud-based settings, offering unprecedented service agility and cost effectiveness. Researchers have also investigated a wide range of VNF placement and SFC provisioning strategies to achieve various operator and client objectives. Nevertheless, most studies on VNF placement and SFC embedding have only considered operation across larger cloud-based settings. These infrastructures are comprised of large core datacenter sites with abundant storage and computational resources. However cloud computing is not well-suited for highly time-sensitive real-time services and applications, i.e., with tight delay and delay-jitter requirements. Localized contextual data support is also quite problematic, e.g., for services such as weather or traffic. In addition, cloud-based services also increase traffic demands across the network along with vulnerability to remote failures and outages. It is here that edge/fog computing paradigms offer much promise by placing smaller storage and computing pools closer to the end-users. These designs can provide much lower service delays, improved localized information support, and reduced network bandwidth overheads. Hence there is a growing need to extend NFV provisioning by fully leveraging fog-based infrastructures to properly support stringent end-user service needs. This remains a largely open problem area today. Overall provisioning NFV services over fog-based networks imposes some key differences versus cloud-based operation. Most notably, fog nodes have orders magnitude less resources and capabilities in terms of storage, computation, and bandwidth interconnectivity. As a result resource constraints become a critical factor, along with service delays. To address these challenges, this research dissertation presents a detailed investigation of SFC provisioning in NFV-enabled fog computing networks. Specifically, novel SFC mapping schemes are developed for the fog domain by taking into account important client parameters, i.e., delay, bandwidth, node resources, and function dependency. Furthermore, several survivability provisions are also presented to improve the reliability of these methods, i.e., including pre-fault protection and post-fault restoration methodologies. Overall these contributions provide a solid base from which to leverage NFV technologies at the network edge

Grating Lobes for Enhanced Scattering Intensity in Millimeter Wave Sparse Channels

Millimeter Wave bands suffer from various channel impairments, such as path loss and blockage sensitivity. Hence, mmWave channels have widely been termed as sparse channels, composed of limited number of rays and clusters. Therefore, analog beamforming architectures become less practical due to its single beam transmission, which can result in link failure due to blockage effects. However, analog beamforming requires very efficient power and energy consumption levels, as compared to digital and hybrid solutions. Hence in this paper, a novel multi-beam analog beamforming transmission technique is proposed that increases the scattering intensity in mmWave sparse channels. This in return allows analog beamforming channels to be increasingly rich-scattering. Namely, grating lobes are deliberately generated for an analog beamformer to increase the scattering intensity in non-line of sight environments, and hence increasing the number of scattering (rays and clusters) in the received signal power delay profile. Simulation results show that channel intensity significantly increases when grating lobes are enabled at one-wavelength antenna spacing, as compared to half-wavelength spacing

Clustered and Distributed Caching Methods for F-RAN-Based mmWave Communications

Fog-radio access networks (F-RANs) alleviate fronthaul delays for cellular networks as compared to their cloud counterparts. This allows them to be suitable solutions for networks that demand low propagation delays. Namely, they are suitable for millimeter wave (mmWave) operations that suffer from short propagation distances and possess a poor scattering environment (low channel ranks). The F-RAN here is comprised of fog nodes that are collocated with radio remote heads (RRHs) to provide local processing capabilities for mobile station (MS) terminals. These terminals demand various network functions (NFs) that correspond to different service requests. Now, provisioning these NFs on the fog nodes also yields service delays due to the requirement for service migration from the cloud, i.e., offloading to the fog nodes. One solution to reduce this service delay is to provide cached copies of popular NFs in advance. Hence, it is critical to study function popularity and allow for content caching at the F-RAN. This is further a necessity given the limited resources at the fog nodes, thus requiring efficient resource management to enhance network capacity at reduced power and cost penalty. This paper proposes novel solutions that allocate popular NFs on the fog nodes to accelerate services for the terminals, namely, the clustered and distributed caching methods. The two methods are analyzed and compared against the baseline uncached provisioning schemes in terms of service delay, energy consumption, and cost