Beam alignment for İEEE 802.11be powered by task oriented indoor UWB localization

Abstract

This study proposes an Ultra-Wide-Band (UWB) assisted location-aware and task-oriented beam alignment system for WiFi7 networks. Coordinated beamforming is one of the crucial improvements for WiFi7. Still, traditional methods, which involve searching for the optimal beam within a large codebook, result in significant delays due to the extensive search space. The proposed method leverages UWB-assisted localization to adjust beams for users rapidly, ensuring precise alignment. The proposed system's core is built around IEEE 802.15.4z UWB, capable of high-precision localization with four anchors distributed in an indoor area. These anchors enable the Access Point (AP) to align its beams much faster to the Station (STA) by testing only the relevant beam patterns using the device's precise location. A task-oriented flow control mechanism is proposed to enhance the scalability of UWB-assisted beam alignment, considering both the Received Signal Strength Indicator (RSSI) from the STA and localization performance. Using Time Difference of Arrival (TDoA) based localization, the system calculates the position of the STA by resolving the time differences in signal arrival at distinct anchors. This information is refined using a Kalman filter to mitigate measurement noise and accurately predict system states. The Kalman filter's state estimation error is integrated into the positioning system to improve the accuracy of the STA's location. This allows the system to employ UWB localization only when necessary, optimizing efficiency judiciously. Location-aware beamforming is facilitated by initiating scans with beams closely aligned with the STA's direction relative to the AP, thereby reducing scanning time. Task-oriented beam alignment employs an Exponentially Weighted Moving Average (EWMA) filter to track RSSI degradation and state estimation errors, triggering UWB localization only when necessary. This approach reduces UWB beacon transmissions, enhancing system scalability. This study conducted extensive evaluations using an OMNET++ based simulation environment, complemented by the INET framework, to assess the performance of the proposed location-aware and task-oriented beam alignment system for WiFi7. The simulation setup comprised one Access Point (AP) and one Station (STA), ensuring constant line-of-sight links, with four Ultra-Wide-Band (UWB) anchors enhancing localization precision. A path-loss model based on Rician Fading was employed to mimic real-world scenarios, and a Parabolic antenna model for the AP simulated beam patterns, focusing solely on the main lobe. During simulations, the STA periodically transmitted beacons to the anchors, facilitating TDoA based localization, which provided the AP with precise STA locations for beam alignment. Results from these simulations demonstrated an 11.6% improvement in beamforming gain by comparing the traditional beam scanning method and a 55.6% enhancement in communication effectiveness compared to conventional UWB localization-assisted methods.