Bluetooth stack

About: Bluetooth stack is a research topic. Over the lifetime, 90 publications have been published within this topic receiving 1096 citations. The topic is also known as: BlueZ.

Every smart phone is a backscatter reader: Modulated backscatter compatibility with Bluetooth 4.0 Low Energy (BLE) devices

Abstract: In this work, we show how modulated backscatter signals can be crafted to yield channelized band-pass signals akin to those transmitted by many conventional wireless devices. As a result, conventional wireless devices can receive these backscattered signals without any modification (neither hardware nor software) to the conventional wireless device. We present a proof of concept using the Bluetooth 4.0 Low Energy, or BLE, standard widely available on smart phones and mobile devices. Our prototype backscatter tag produces three-channel bandpass frequency shift keying (FSK) packets at 1 Mbps that are indistinguishable from conventional BLE advertising packets. An unmodified Apple iPad is shown to correctly receive and display these packets at a range of over 9.4 m using its existing iOS Bluetooth stack with no changes whatsoever. We create all three BLE channels by backscattering a single incident CW carrier using a novel combination of fundamentalmode and harmonic-mode backscatter subcarrier modulation, with two of the band-pass channels generated by the fundamental mode and one of the band-pass channels generated by the second harmonic mode. The backscatter modulator consumes only 28.4 pJ/bit, compared with over 10 nJ/bit for conventional BLE transmitters. The backscatter approach yields over 100X lower energy per bit than a conventional BLE transmitter, while retaining compatibility with billions of existing Bluetooth enabled smartphones and mobile devices.

Bluetooth: technology for short-range wireless apps

Abstract: In 1998, five major companies (Ericsson, Nokia, IBM, Toshiba and Intel) formed a group to create a license-free technology for universal wireless connectivity in the handheld market. The result is Bluetooth, a technology named after a 10th-Century king who brought warring Viking tribes under a common rule. The Bluetooth specifications (currently in version 1.1) define a radiofrequency (RF) wireless communication interface and the associated set of communication protocols and usage profiles. The link speed, communication range and transmission power level for Bluetooth were chosen to support low-cost, power-efficient, single-chip implementations of the current technology. In fact, Bluetooth is the first attempt at making a single-chip radio that can operate in the 2.4-GHz ISM (industrial, scientific and medical) RF band. While most early Bluetooth solutions are dual-chip, vendors have recently announced single-chip versions as well. In this overview of the technology, I first describe the lower layers of the Bluetooth protocol stack. I also briefly describe its service discovery protocol and, finally, how the layers of the protocol stack fit together from an application's point of view.

Bluetooth and sensor networks: a reality check

Abstract: The current generation of sensor nodes rely on commodity components. The choice of the radio is particularly important as it impacts not only energy consumption but also software design (e.g., network self-assembly, multihop routing and in-network processing). Bluetooth is one of the most popular commodity radios for wireless devices. As a representative of the frequency hopping spread spectrum radios, it is a natural alternative to broadcast radios in the context of sensor networks. The question is whether Bluetooth can be a viable alternative in practice. In this paper, we report our experience using Bluetooth for the sensor network regime. We describe our tiny Bluetooth stack that allows TinyOS applications to run on Bluetooth-based sensor nodes, we present a multihop network assembly procedure that leverages Bluetooth's device discovery protocol, and we discuss how Bluetooth favorably impacts in-network query processing. Our results show that despite obvious limitations the Bluetooth sensor nodes we studied exhibit interesting properties, such as a good energy per bit sent ratio. This reality check underlies the limitations and some promises of Bluetooth for the sensor network regime.

BLE-Backscatter: Ultralow-Power IoT Nodes Compatible With Bluetooth 4.0 Low Energy (BLE) Smartphones and Tablets

Abstract: Backscatter communication promises significant power and complexity advantages for Internet of Things devices such as radio frequency identification (RFID) tags and wireless sensor nodes. One perceived disadvantage of backscatter communication has been the requirement for specialized hardware such as RFID readers to receive backscatter signals. In this paper, we show how backscatter signals can be designed for compatibility with the Bluetooth 4.0 low energy (BLE) chipsets already present in billions of smart phones and tablets. We present a prototype microcontroller-based “BLE-Backscatter” tag that produces bandpass frequency-shift keying modulation at 1 Mb/s, enabling compatibility with conventional BLE advertising channels. Using a +23-dBm equivalent isotropically radiated power continuous wave (CW) carrier source, we demonstrate a range of up to 13 m between the tag and an unmodified Apple iPad Mini as well as a PC with the Nordic Semiconductor nRF51822 chipset. With the tag 1 m from the receiver, we demonstrate a range of up to 30 m between the CW carrier source and the tag. In both cases, the existing Bluetooth stack was used, with no modifications whatsoever to hardware, firmware, or software. The backscatter tag consumes only 1.56 nJ/b, over $6\times $ less than the lowest power commercial Bluetooth transmitters.

Location privacy in bluetooth

Abstract: We discuss ways to enhance the location privacy of Bluetooth. The principal weakness of Bluetooth with respect to location privacy lies in its disclosure of a device’s permanent identifier, which makes location tracking easy. Bluetooth’s permanent identifier is often disclosed and it is also tightly integrated into lower layers of the Bluetooth stack, and hence susceptible to leakage. We survey known location privacy attacks against Bluetooth, generalize a lesser-known attack, and describe and quantify a more novel attack. The second of these attacks, which recovers a 28-bit identifier via the device’s frequency hop pattern, requires just a few packets and is practicable. Based on a realistic usage scenario, we develop an enhanced privacy framework with stronger unlinkability, using protected stateful pseudonyms and simple primitives.