Towards Quality of Service Guarantees in Bluetooth A Cross-Layer Framework for LE and Classic Coexistence in the 2.4 GHz IoT Ecosystem

Abstract

Bluetooth technology has become foundational for short-range communication in a wide range of Internet of Things (IoT) applications, encompassing both Bluetooth Low Energy (LE) and Classic protocols. With the 2.4 GHz ISM band increasingly congested by coexisting technologies such as Wi-Fi, Zigbee, and proprietary wireless protocols, Bluetooth now faces critical challenges in delivering consistent Quality of Service (QoS) for time-sensitive and bandwidth-intensive use cases. In contrast to Wi-Fi, which benefits from robust QoS frameworks like IEEE 802.11e and Wi-Fi Multimedia (WMM), Bluetooth's current design lacks built-in mechanisms for traffic prioritization, deterministic latency, or adaptive scheduling. This paper identifies core limitations of Bluetooth’s transport architecture under interference-prone conditions and proposes a novel cross-layer QoS framework. Our design introduces traffic classification at the application layer, connection event prioritization at the link layer, coexistence-aware adaptive frequency hopping, and enhanced controller-host coordination through vendor-specific HCI extensions. We validate the proposal using simulations and empirical tests involving mixed BLE/Classic traffic and controlled Wi-Fi interference. The results demonstrate improvements in latency, jitter, and reliability, especially for critical IoT use cases such as voice, telemetry, and health monitoring. The framework provides a scalable path forward for integrating Bluetooth QoS into future specifications and enabling its use in high-density, real-time applications.