# Accurate Angular Inference for 802.11ad Devices Using Beam-Specific Measurements

## TL;DR

This paper introduces VAE-CIR, a novel variation-based angular inference method for 802.11ad devices that leverages beam-specific channel impulse response variations to improve accuracy in sparse 60GHz channels.

## Contribution

It proposes a new angular inference technique that exploits CIR variations across beams, outperforming existing methods for 802.11ad devices with limited RF capabilities.

## Key findings

- VAE-CIR achieves higher angular inference accuracy.
- Simulation results demonstrate VAE-CIR's superiority over existing schemes.
- Effective in various realistic scenarios.

## Abstract

Due to their sparsity, 60GHz channels are characterized by a few dominant paths. Knowing the angular information of their dominant paths, we can develop various applications, such as the prediction of link performance and the tracking of an 802.11ad device. Although they are equipped with phased arrays, the angular inference for 802.11ad devices is still challenging due to their limited number of RF chains and limited phase control capabilities. Considering the beam sweeping operation and the high communication bandwidth of 802.11ad devices, we propose variation-based angle estimation (VAE), called VAE-CIR, by utilizing beam-specific channel impulse responses (CIRs) measured under different beams and the directional gains of the corresponding beams to infer the angular information of dominant paths. Unlike state-of-the-arts, VAE-CIR exploits the variations between different beam-specific CIRs, instead of their absolute values, for angular inference. To evaluate the performance of VAE-CIR, we generate the beam-specific CIRs by simulating the beam sweeping of 802.11ad devices with the beam patterns measured on off-the-shelf 802.11ad devices. The 60GHz channel is generated via a ray-tracing simulator and the CIRs are extracted via channel estimation based on Golay sequences. Through experiments in various scenarios, we demonstrate the effectiveness of VAE-CIR and its superiority to existing angular inference schemes for 802.11ad devices.