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What to do With the Wi-Fi Wild West

Periodic Reporting for period 3 - Wi-5 (What to do With the Wi-Fi Wild West)

Reporting period: 2017-01-01 to 2018-04-30

The Wi-5 project aimed to address the issues of radio interference and spectrum inefficiency, which is important for increasing Wi-Fi capacities to support fast growing demand for Wi-Fi services. By integrating novel smart functionalities into Wi-Fi Access Points (APs), Wi-5 enables local coordination to reduce radio interference and optimize Wi-Fi spectrum usage. An inter-operator cooperation platform has been developed to allow coordination between APs of different operators and support seamless handover/offloading to other Wi-Fi networks or to non-Wi-Fi networks such as 3G/4G/5G or fixed networks. Wi-5 also supports the use of packet grouping techniques to maximise the efficiency of small-packet applications such as voice and gaming applications. The developed functionalities have been integrated into a single optimized Wi-5 architecture and an Openflow-based Software Defined Networking (SDN) approach has been adopted to manage the resulting wireless network. Figure 1 outlines the architecture and the main functionalities proposed in Wi-5 for integration in Wi-Fi APs.

Wi-5 was funded by the EC for a duration of 40 months (January 2015 – April 2018) and was led by Liverpool John Moores University. The full consortium is as follows.
• Liverpool John Moores University (LJMU), UK
• Nederlandse Organisatie voor Toegepast (TNO), Netherlands
• Universidad de Zaragoza (UniZar), Spain
• AirTies Kablosuz İletişim San. ve Dış Tic. A.Ş (AirTies), Turkey
• PrimeTel Telecommunications (PLC), Cyprus
Wi-5 has developed and implemented a range of smart and cooperative solutions that were integrated into the Wi-5 architecture, which takes into account the requirements for new business roles to support Wi-5 operations and the use cases we envision. These roles will not only facilitate Intra-Operator Cooperation on the spectrum plane, but will also enable Inter-Operator Cooperation on the business plane. We have validated this approach through simulation and modelling, and extensive interaction with a group of network operators and other stakeholders.

As part of the integrated Wi-5 solution, a novel set of functionalities have been developed that address the lack of flexibility in the management and utilisation of IEEE 802.11 WLANs, which are not inherently cooperative in nature. These functionalities include the following notable features:

1. Radio Resource Management (RRM) to address interference in Wi-Fi networks by combining both AP channel assignment and transmit power adjustment techniques. Our approach improves the application flow Quality of Service (QoS) through transmit power control, while at the same time considering the effect of the Radio Frequency (RF) channels configuration on the rest of the network. Our RRM algorithm was compared against existing approaches and our results show that it performs better than the state of the art in terms of interference, Signal to Interference plus Noise Ratio (SINR), spectrum efficiency and users satisfaction.
2. Smart AP selection, which associates users to Wi-Fi APs based on an innovative performance and QoS evaluation metric called Network Fittingness Factor (FF), efficiently addresses the QoS requirements of both a flow joining the network and other flows active in the network. This was extended in later versions to introduce a centralised potential game which provides better performance. We compared our solution against existing approaches found in the literature, demonstrating that our strategy performs better than the state of the art in terms of users’ satisfaction, blocking probability and Quality of Experience (QoE).
3. Vertical Handover algorithm that extends our AP Selection algorithm to select the most suitable connection between Wi-Fi APs and 3G/4G Base Stations (BSs) for each new user/flow running in a dual-interface device, such as a smartphone or a tablet.
4. Centrally coordinated packet grouping which aggregates small packets based on existing 802.11 standards but considers the trade-off between efficiency and latency based on the user requirements. Our approach also considers how this can be intelligently applied in a managed wireless network. Our results show significant efficiency savings can be introduced with little or no impact on the user’s perceived performance.

We have integrated the above features into a prototype real-time SDN platform based on Odin. Specifically, the smart AP monitoring, channel selection, and seamless handover functionalities have been employed to drive the channel assignment and AP selection algorithms and the seamless handover functionality has also been integrated as part of the load balancing functionality. This proof of concept implementation has been developed as an open source project ( and we have rigorously tested and improved the system as part of our work. This includes extensive testing in a test house lab environment and a number of real world deployments and user trials.

Wi-5 had an extensive plan to maximize our impact through scientific dissemination, industrial exploitation, and standardization. From 2015 to 2018 we have written and published over 10 high quality journal papers and presented a similar number of papers at a number of well-respected international conferences. In addition, Wi-5 has submitted a number of contributions to standardisation bodies including the IETF, HGI, and BBF. Finally, each member of the consortium is committed to pursuing a range of exploitation options in their respective markets and are actively attempting to engage external partners to further exploit the results. In addition, Wi-5 engaged effectively with industry through our Operator Board which provided periodic input and feedback to better tune our work to the needs of the market.
Wi-5 has made a number of innovative and novel contributions that position it beyond the current state of the art:
• We have developed and published the Wi-5 architecture that is supported by a new matching business model to solve the tragedy of the commons in Wi-Fi networks
• Abstracted and advanced the concept of radio resource management to define a programmable wireless ‘spectrum plane’
• Defined and implemented a novel suite of smart functionalities that comprehensively enhance current Wi-Fi APs and offer seamless handovers 20x faster than the state of the art
• The new cooperative functionalities have been shown to improve overall network performance and reduce interference in real time through channel assignment, power control, and AP selection
• The Wi-5 system has been implemented as an innovative proof of concept prototype and deployed in a range of environments, including real world systems

These contributions are shown in the context of the Wi-5 architecture in figure 2:

Regarding impact, the Wi-5 platform supports the concept of Wi-Fi cooperation based on coordinated AP selection and channel allocation through a shared SDN-based platform. This has allowed us to make significant contributions towards increasing global wireless capacity. It can determine the requirements of an application being served over Wi-Fi and can tune the network configuration based on the user QoE requirements. Our results show a significant improvement in both spectrum efficiency and end users’ satisfaction in the face of both internal and external interference, which offers considerable benefits to both Wi-Fi network operators and their users.
Wi-5 Project Logo
Figure 2 - Novel contributions of the Wi-5 project
Figure 1 - The Wi-5 architecture