Airtime usage control in virtualized multi-cell 802.11 networks

This paper investigates the station (STA)-access point (AP) association and airtime control for virtualized 802.11 networks to provide service customization and fairness across multiple Internet service-providers (ISPs) sharing the common physical infrastructure and network capacity. More specifically, an optimization problem is formulated on the STAs' transmission probabilities to maximize the overall network throughput, while providing airtime usage guarantees for the ISPs. Subsequently, an algorithm to reach the optimal solution is developed by applying monomial approximation and geometric programming iteratively. Illustrative results confirm the superior and robust performance of the developed association and airtime control scheme in terms of both throughput and fairness

AP-STA association control for throughput maximization in virtualized WiFi networks

To manage and enable service customization among multiple internet service providers (ISPs) sharing the common physical infrastructure and network capacity in virtualized Wi-Fi networks, this paper models and optimizes access point-station (STA) association via airtime usage control. More specifically, an optimization problem is formulated on the STAs’ transmission probabilities to maximize the overall network throughput, while providing airtime usage guarantees for the ISPs. As the proposed optimization problem is inherently non-convex, an algorithm to reach the optimal solution is developed by applying monomial approximation and geometric programming iteratively. Based on the proposed 3-D Markov-chain model of the enhanced distributed channel access protocol, the detailed implementation of the optimal transmission probability of each STA is also discussed by manipulating medium access control parameters. The performance of the developed association and airtime control scheme is evaluated through numerical results. For both homogeneous and non-homogeneous STA distributions, numerical results reveal performance gains of the proposed algorithm in improving the throughput and keeping airtime usage guarantees

Resource slicing in virtual wireless networks: a survey

New architectural and design approaches for radio access networks have appeared with the introduction of network virtualization in the wireless domain. One of these approaches splits the wireless network infrastructure into isolated virtual slices under their own management, requirements, and characteristics. Despite the advances in wireless virtualization, there are still many open issues regarding the resource allocation and isolation of wireless slices. Because of the dynamics and shared nature of the wireless medium, guaranteeing that the traffic on one slice will not affect the traffic on the others has proven to be difficult. In this paper, we focus on the detailed definition of the problem, discussing its challenges. We also provide a review of existing works that deal with the problem, analyzing how new trends such as software defined networking and network function virtualization can assist in the slicing. We will finally describe some research challenges on this topic.Peer ReviewedPostprint (author's final draft

Slicing in WiFi networks through airtime-based resource allocation

Network slicing is one of the key enabling technologies for 5G networks. It allows infrastructure owners to assign resources to service providers (tenants), which will afterwards use them to satisfy their end-user demands. This paradigm, which changes the way networks have been traditionally managed, was initially proposed in the wired realm (core networks). More recently, the scientific community has paid attention to the integration of network slicing in wireless cellular technologies (LTE). However, there are not many works addressing the challenges that appear when trying to exploit slicing techniques over WiFi networks, in spite of their growing relevance. In this paper we propose a novel method of proportionally distributing resources in WiFi networks, by means of the airtime. We develop an analytical model, which shed light on how such resources could be split. The validity of the proposed model is assessed by means of simulation-based evaluation over the ns-3 framework.This work has been supported in part by the European Commission and the Spanish Government (Fondo Europeo de desarrollo Regional, FEDER) by means of the EU H2020 NECOS (777067) and ADVICE (TEC2015-71329) projects, respectively

Control-theoretic approaches for efficient transmission on IEEE 802.11e wireless networks

With the increasing use of multimedia applications on the wireless network, the functionalities of the IEEE 802.11 WLAN was extended to allow traffic differentiation so that priority traffic gets quicker service time depending on their Quality of Service (QoS) requirements. The extended functionalities contained in the IEEE Medium Access Control (MAC) and Physical Layer (PHY) Specifications, i.e. the IEEE 802.11e specifications, are recommended values for channel access parameters along traffic lines and the channel access parameters are: the Minimum Contention Window CWmin, Maximum Contention Window CWmax, Arbitration inter-frame space number, (AIFSN) and the Transmission Opportunity (TXOP). These default Enhanced Distributed Channel Access (EDCA) contention values used by each traffic type in accessing the wireless medium are only recommended values which could be adjusted or changed based on the condition of number of associated nodes on the network. In particular, we focus on the Contention Window (CW) parameter and it has been shown that when the number of nodes on the network is small, a smaller value of CWmin should be used for channel access in order to avoid underutilization of channel time and when the number of associated nodes is large, a larger value of CWmin should be used in order to avoid large collisions and retransmissions on the network. Fortunately, allowance was made for these default values to be adjusted or changed but the challenge has been in designing an algorithm that constantly and automatically tunes the CWmin value so that the Access Point (AP) gives out the right CWmin value to be used on the WLAN and this value should be derived based on the level of activity experienced on the network or predefined QoS constraints while considering the dynamic nature of the WLAN. In this thesis, we propose the use of feedback based control and we design a controller for wireless medium access. The controller will give an output which will be the EDCA CWmin value to be used by contending stations/nodes in accessing the medium and this value will be based on current WLAN conditions. We propose the use of feedback control due to its established mathematical concepts particularly for single-input-single-output systems and multi-variable systems which are scenarios that apply to the WLAN

Load-Aware Traffic Control in Software-Defined Enterprise Wireless Local Area Networks

With the growing popularity of Bring Your Own Device (BYOD), modern enterprise Wireless Local Area Networks (WLANs) deployments always consist of multiple Access Points (APs) to meet the fast-increasing demand for wireless access. In order to avoid network congestion which leads to issues such as suboptimal Quality of Service (QoS) and degraded user Quality of Experience (QoE), intelligent network traffic control is needed. Software Defined Networking (SDN) is an emerging architecture and intensively discussed as one of the most promising technologies to simplify network management and service development. In the SDN architecture, network management is directly programmable because it is decoupled from forwarding layer. Leveraging SDN to the existing enterprise WLANs framework, network services can be flexibly implemented to support intelligent network traffic control. This thesis studies the architecture of software-defined enterprise WLANs and how to improve network traffic control from a client-side and an AP-side perspective. By extending an existing software-defined enterprise WLANs framework, two adaptive algorithms are proposed to provide client-based mobility management and load balancing. Custom protocol messages and AP load metric are introduced to enable the proposed adaptive algorithms. Moreover, a software-defined enterprise WLAN system is designed and implemented on a testbed. A load-aware automatic channel switching algorithm and a QoS-aware bandwidth control algorithm are proposed to achieve AP-based network traffic control. Experimental results from the testbed show that the designed system and algorithms significantly improve the performance of traffic control in enterprise WLANs in terms of network throughput, packet loss rate, transmission delay and jitter