Practical time synchronization for Bluetooth Scatternets

Ringwald, Matthias; Römer, Kay Uwe

doi:10.1109/broadnets.2007.4550453

Cited by 22 publications

(16 citation statements)

References 5 publications

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“…One approach is use the Bluetooth clock to synchronize the slaves to the master [3] or other layer-2 techniques. Synchronized time division access protocols can also be used [1].…”

Section: Introduction and Related Workmentioning

confidence: 99%

Local Time Synchronization in Bluetooth Piconets for Data Fusion Using Mobile Phones

Wåhslén

Orhan

Lindh

2011

2011 International Conference on Body Sensor Networks

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This paper presents a method to synchronize the clocks in a Bluetooth piconet from the application layer in a mobile phone. It adapts algorithms for time synchronization of distributed systems and the Internet to Bluetooth networks. The performance issues that cause problems for data synchronization between master and slaves in Bluetooth are highlighted. The tests show that the synchronization error is limited to one sampling time. I. INTRODUCTION AND RELATED WORKApplications in mobile phones that collect and analyze data from multiple wireless sensors have become wide-spread today e.g., in sports, leisure and for physical activities in general. In this paper we present a method to synchronize the clocks between the master and the slaves in a Bluetooth piconet in order to perform data fusion of data from multiple sensors with correct timestamps. One example is collecting data from several inertial sensors placed along the legs of a cyclist to measure the ankle and knee angles and provide feedback to optimize performance [1]. Another application, also estimating the knee angle from wireless inertial sensors, is gait analysis e.g., for recovery and rehabilitation after a knee surgery.The main problem studied in this paper is to associate samples from different sensors that are taken at approximately the same time in order to perform data fusion. One approach is use the Bluetooth clock to synchronize the slaves to the master [3] or other layer-2 techniques. Synchronized time division access protocols can also be used [1]. A comprehensive survey of time synchronization in wireless sensor networks can be found in [4]. Our approach is to achieve data synchronization from the application layer, without having access to the internal Bluetooth stack. It is sometimes not possible or even desirable, to program the wireless sensor nodes. In previous work we have presented an algorithm on the mobile phone for data synchronization without any time information in the data samples sent from the sensor nodes [5]. In this paper we propose a method to synchronize the sensor nodes' clocks using a combination of methods for distributed systems (see brief overview in [6]) and the Network Time Protocol (NTP) [7] for the Internet, adapted to Bluetooth and mobile phones.The paper is organized as follows. Section II introduces our method for time synchronization and the theory behind it. Section III highlights some of the performance issues in Bluetooth that make synchronization of data from multiple sensors on a mobile phone difficult, as described in Section IV.

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“…One approach is use the Bluetooth clock to synchronize the slaves to the master [3] or other layer-2 techniques. Synchronized time division access protocols can also be used [1].…”

Section: Introduction and Related Workmentioning

confidence: 99%

Local Time Synchronization in Bluetooth Piconets for Data Fusion Using Mobile Phones

Wåhslén

Orhan

Lindh

2011

2011 International Conference on Body Sensor Networks

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“…Ringwald et al [7] present a time synchronization protocol for multi-hop Bluetooth networks which builds upon these two commands. The implementation of this protocol was done on the BTnode platform [8] and the approach was evaluated on a 7-hop network of Bluetooth nodes.…”

Section: Time Synchronization Methods In Bluetooth-based Wireless Senmentioning

confidence: 99%

Considerations for Synchronization in Body Area Networks for Human Activity Monitoring

Plomp

Heiskanen

Hillukkala

et al. 2011

Int J Wireless Inf Networks

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In this paper, we highlight considerations for synchronization issues in body area networks. Requirements for the synchronization accuracy in body area networks depend on the application at hand. Synchronization may be needed for power management, sample ordering, calculation of stimulus responses and for sensor fusion. This paper provides a theoretical exercise to help understand the accuracy required for typical human motion sensing. It gives an overview of various synchronisation strategies used and implemented in prototype systems. Lessons learnt from practical implementations using Bluetooth, an IEEE 802.15.4 proprietary network and Nanonet are presented to illustrate the principles involved.The discussion provides some considerations and the requirements for typical WBAN applications.

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“…5. Description of how the "read clock" command is processed by a Bluetooth module [22] a Health Device Profile (HDP), SPP has been chosen since for data streaming the two profiles are comparable in terms of packet loss [21].…”

Section: Piconet Clock Synchronization Methodsmentioning

confidence: 99%

“…Figure 5 represents what happens when a command is issued to Bluetooth node. It is possible that when the command is issued (t 1 ), the host controller is busy for other operations [22], and the response does not occur soon after processing (t 2 ), but instead may be delayed and sent after completing other operations (t 3 ). It has to be noted that the Bluetooth module does not transmit any data while in command mode, but it can accept incoming connections and is visible to other devices.…”

Section: F Bluetooth Clock Correctionmentioning

confidence: 98%

Synchronization methods for Bluetooth based WBANs

Casamassima

Farella

Benini

2013

2013 IEEE International Conference on Body Sensor Networks

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Wireless Body Area Networks (WBANs) can take advantage of many wireless protocols. Among them, Bluetooth is a good candidate since its widespread adoption guarantees compatibility with a number of devices and significantly reduces development time. In most cases data collected from different sensors on different nodes need to be synchronized. We present a synchronization protocol that makes use of Bluetooth piconet internal clock to achieve near-millisecond accuracy with minimal radio communication overhead. Experimental results show that Bluetooth low power modes does not affect negatively accuracy, but improves it, obtaining less power consumption and higher synchronization accuracy.

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Practical time synchronization for Bluetooth Scatternets

Cited by 22 publications

References 5 publications

Local Time Synchronization in Bluetooth Piconets for Data Fusion Using Mobile Phones

Local Time Synchronization in Bluetooth Piconets for Data Fusion Using Mobile Phones

Considerations for Synchronization in Body Area Networks for Human Activity Monitoring

Synchronization methods for Bluetooth based WBANs

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