GR-WiFi: A GNU Radio based WiFi Platform with Single-User and Multi-User MIMO Capability (2501.06176v1)

Abstract: Since its first release, WiFi has been highly successful in providing wireless local area networks. The ever-evolving IEEE 802.11 standards continue to add new features to keep up with the trend of increasing numbers of mobile devices and the growth of Internet of Things (IoT) applications. Unfortunately, the lack of open-source IEEE 802.11 testbeds in the community limits the development and performance evaluation of those new features. Motivated by an existing popular open-source software-defined radio (SDR) package for single-user single-stream transmission based on the IEEE 802.11/a/g/p standard, in this paper we present GR-WiFi, an open-source package for single-user and multi-user multi-input multi-output (MIMO) transmissions based on 802.11n and 802.11ac standards. The distinct features of GR-WiFi include the support of parallel data streams to single or multiple users, and the compatible preamble processing to allow the co-existence of conventional, high-throughput (HT) and very-high-throughput (VHT) traffics. The performance of GR-WiFi is evaluated through both extensive simulation and real-world experiments.

• The paper demonstrates an open-source GNU Radio platform that supports both single-user and multi-user MIMO to enhance throughput in IEEE 802.11n/ac networks.
• It validates GR-WiFi’s performance with simulations and testbed experiments, showing improved robustness against channel impairments compared to legacy SISO systems.
• The design’s backward compatibility with legacy IEEE standards and use of cyclic shift diversity lay the foundation for scalable wireless communication research.

Overview of "GR-WiFi: A GNU Radio Based WiFi Platform with Single-User and Multi-User MIMO Capability"

The paper introduces GR-WiFi, an open-source software-defined radio (SDR) framework developed to address the need for a research and evaluation platform in the field of IEEE 802.11 standards, specifically targeting the 802.11n and 802.11ac standards which include single-user MIMO (SU-MIMO) and multi-user MIMO (MU-MIMO) capabilities. By extending the capabilities of existing SDR WiFi projects primarily limited to single-input single-output (SISO) streams, the authors aim to provide a flexible and scalable tool for testing and innovation in MIMO technologies, which are paramount for accommodating the growing demands of high-throughput communication in wireless local area networks (WLANs).

Key Features and Implementations

GR-WiFi is distinguished by its support for both single-user and multi-user MIMO transmissions, facilitating the transmission of parallel data streams to a single or multiple users. This feature offers significant throughput and efficiency improvements over traditional single-stream setups. The platform's backbone is built on GNU Radio, a widely utilized open-source toolkit facilitating real-time signal processing and radio communications.

The design of GR-WiFi ensures compatibility and coexistence of legacy formats from IEEE 802.11a/g with the high throughput (HT) and very high throughput (VHT) formats of IEEE 802.11n/ac. This is particularly beneficial for researchers who require backward compatibility in their test scenarios. The developers efficiently utilize cyclic shift diversity (CSD) to map single-stream data across multiple transmit antennas in the preamble phase, a technique that aids in preventing unintentional beamforming effects that could disrupt signal reception.

Technical Evaluation and Performance

The performance of GR-WiFi was rigorously evaluated through both simulations and testbed experiments. These assessments explored packet delivery ratios (PDR) across various modulation and coding schemes (MCS) in both AWGN and channel-simulated environments like TGac, which introduce multipath fading conditions.

For SISO configurations, the results favorably compared GR-WiFi's performance to existing solutions like WIME and commercial chipsets such as Intel's AX210 adapter. GR-WiFi consistently demonstrated enhanced robustness against phase distortions such as CFO, illustrative of the meticulous channel estimation and synchronization techniques employed.

In SU-MIMO and MU-MIMO scenarios, the evaluations detailed the systems' adeptness at handling inter-stream interference and showcased how GR-WiFi met theoretical performance expectations under controlled laboratory conditions. For SU-MIMO, the platform efficiently utilized parallel stream capability to emulate realistic high-throughput scenarios. MU-MIMO implementations were verified using configurations with two transmit antennas and two single-antenna receivers, showcasing the system's ability to utilize spatial multiple access efficiently.

Implications and Future Developments

From a practical standpoint, the creation of GR-WiFi offers an invaluable tool for academic and industry research, facilitating advancements in wireless communication protocols and technologies. Its open-source nature allows the customization necessary for timely research in next-generation networks and potential integration with emerging WLAN standards such as IEEE 802.11ax and beyond.

Theoretically, GR-WiFi represents a significant stepping stone towards achieving scalable MU-MIMO networks, essential for addressing the increasing bandwidth and efficiency requirements in a variety of applications—from personal devices to IoT infrastructures. Future work includes expanding GR-WiFi's scope to support more advanced MIMO configurations, increasing its PHY data rate capabilities, and enhancing its adaptability to future IEEE 802.11 standard evolutions.

Overall, GR-WiFi stands as a robust testament to the ongoing need for comprehensive, open-source evaluation platforms in the field of wireless communications, particularly for the intricate requirements that come with MIMO technologies. Through continuous development and community contribution, it holds the potential to drive innovation and optimization in the wireless communication landscape.