GSoC 2024: New Transmit Power Control Approach for IEEE 802.11ax Wifi chips

1. Introduction

Hi everyone. I am Raul Shahi. I am currently pursuing a Master’s degree in Computer Engineering for IoT Systems from Nordhausen University of Applied Sciences, Nordhausen, Germany. For the past couple of months, I have undertaken the position of Research Assistant at my university, which involves researching and developing open-source software for IEEE 802.11 resource allocation.

For GSoC 2024, I will work on a novel Power Control algorithm to reduce interference and increase aggregate network throughput. This introductory blog post intends to summarize the necessary background to understand the details of the project.

2. Leveraging TPC performance for enhanced WiFi Performance

Regarding WiFi networks, ensuring everything runs smoothly is all about how we manage the available resources. As the concept of WiFi resource allocation has been covered by Prashiddha during his GSoC projects before, I would suggest the readers refer to his blog posts [3][4]. For IEEE 802.11 devices, deep diving into the system internals is required which can be overwhelming for developers as they would have to be familiar with kernel subsystems and Ansi C. This technical barrier makes it tough to adapt and innovate with new algorithms.

On top of that, many of the latest WiFi chips are becoming closed-source which means the open-source community can have a harder time developing new and advanced algorithms. However, chips like Mediatek, still share throughput information which can be utilized for the optimization of WiFi networks.

Active Transmit Power Control (TPC) is an exciting development area. By adjusting the transmit power for different devices, TPC algorithm extensions like Minstrel-Blues which is built on top of the Minstrel rate control algorithm are promising. They can reduce interference, boost overall network throughput, and improve how the network handles multiple devices in crowded spaces.

3. Motivation

To solve the challenges in WiFi resource allocation, the SupraCoNex project introduced the user-space WiFi Parameter Control API and an interface called Python-WiFi-Manger to enable the development of algorithms using Python. Developers can use these tools to create and test their algorithms on real WiFi chips. On top of the API, a remote socket extension has been realized to facilitate the remote management of access points. The API allows users to monitor transmission data and adjust rates and power on access points without technical knowledge of the kernel. 

I propose developing a new transmit power control algorithm using the WiFi-Manager for IEEE 802.11 ac chips, based on throughput estimates. This approach could potentially extend to Mediatek ax chips, paving the way for smarter, more efficient WiFi networks. However, the approach can be easily extended to any chips that expose the estimated throughput information and provide an interface to fine-tune power settings in real-time.

4. Methodology

The WiFi-Manager package in Python allows the user to monitor each transmitted frame while leveraging the options to control the rate and power for each connected access point. The first task will be to create a new Python package for the power controller and integrate it with WiFi-Manager. Since WiFi-Manager does not yet include throughput information, we will either add it to WiFi-Manager for broader use or directly into the power controller.

The power controller will track throughput at different power levels and average these observations using techniques like the Butterworth filter on EWMA. This can be the basis for determining the optimal transmission power. If throughput suddenly drops, the controller will have a fallback strategy, such as increasing power aggressively to restore the link quickly.

Like the Minstrel-HT [1] and Minstrel-Blues [2] algorithms, our power controller will have update and sample intervals. At the end of each update interval, it will adjust the power level based on recent observations. During sample intervals, it will explore different power levels to find the best settings.

The existing solutions from the Experimentation Python package from SupraConeX can be used to compare the proposed approach, evaluating performance based on rate selection, aggregation, throughput, and power levels.

5. Deliverables of The Project

The end goals of my GSoC 2024 project are as follows:

a. Implementation of a dynamic power control algorithm to adjust power levels
based on throughput information with the ready-to-run demo.


b. A detailed report documenting the research methodology, experimental setup,
results, analysis, and conclusions drawn from the study.


c. A study conducted using the Experimentation Python package that compares
the performance of the proposed approach with the existing solutions on
productive Freifunk Mesh and Access deployments.

6. What has been done until now?

a. Developed a foundational understanding of the importance of resource allocation in wireless transmission.

b. Familiarization with the ‘WiFi-Manager’ package as well as other packages from ‘SupraConeX’.

c. Remote access point setup for monitoring of data transmission and power, rate control.

7. What’s next?

a. Create a Python package for the power controller.

b. Preliminary performance comparison and evaluation of the developed algorithm.

8. Conclusion

I am incredibly grateful to be part of GSoC 2024 as we embark on this exciting journey. Developing and implementing a new power control algorithm with WiFi-Manager is just the beginning, and I am thrilled to contribute to innovations that could significantly improve WiFi performance. This project promises to push the boundaries of what’s possible in wireless communication, and I look forward to sharing our progress and successes with you. 

Please feel free to reach out and connect with me.

References

[1] Minstrel-HT Source Code in the Linux Kernel 

[2] A Measurement-Based Joint Power and Rate Controller for IEEE 802.11 Networks

[3] Minstrel TX Rate Control in User Space, Prashiddha, GSoC ‘22

[4] GSoC ‘22 and ‘23 blog posts from Prashiddha