Bluetooth Quality of Service

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Bluetooth Quality of Service

• A Comnet lab project by
• Omry Yeshurun 037606175
• Dotan Perry 037609708
• Supervisor Alex Sprintson

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Overview Quality of Service
Quality of Service (QoS) is a term relating to
the ability to differentiate between the service
given to certain entities (applications, devices,
flows etc.) For instance real-time applications,
that require a limit on delay time, would receive
higher priority over WWW browsing traffic that is
less sensitive to delay.
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Bluetooth Model Structure
Focus of Project
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Goals

• Implement QoS support into BlueZ stack (L2CAP
  layer).
• Improve support for Real-time application running
  over Bluetooth.
• Demonstrate improved performance in different
  scenarios.

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Project Focus

• QoS is a very broad issue, including many
  aspects, such as transmit and receive priorities,
  drop precedence etc..
• We will focus only on transmit and receive
  priorities.
• BlueZ has many unresolved QoS issues awaiting
  solution, in all layers.
• We will focus on the L2CAP layer, specifically on
  the transmitting and receiving queues to HCI
  layer.

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Current Situation

• L2CAP packets are too big for HCI, and so they
  are segmented into several HCI packets. The HCI
  packets are enqueued and dequeued into the
  transmitting and receiving queues sequentially.
• When a high priority packet arrives, it has to
  wait for previous packets to be transmitted.
• Conclusion There is no provision for QoS support
  in L2CAP.

Refer to www.dei.unipd.it/bigbig/quos/
Bluetooth_QoS_ING_A_part_I.pdf
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Development Issues

• Area of focus
• Altering queue policy vs. altering queue model
• Number of priority levels
• Priority Assignment
• Point of Alteration

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Implementation Overview

• Packet modification All packets will be tagged
  according to the priority given to the connection
  they originated from (high or normal priority).
  Using Reserved fields in L2CAP packet, allow
  the implementation of two classes of service.
• Separate queues for high and low priority
  packets Handling of packets from different
  priorities would be independent, thus creating a
  separate logical link for each priority. Single
  transmit queue per-connection, (i.e. open
  socket), but two receive queues per device.
  High-priority packets will receive precedence in
  reassembly engine.
• Auto-negotiation Upon connection establishment
  and configuration, auto-negotiate QoS
  compatibility on both sides and enable QoS if
  possible, using reserved flags in the
  auto-negotiation protocol.
• Priority assignment packets priority will be
  established per-connection, thus allowing
  connections in need of higher QoS such as video
  or VOIP to receive needed service.

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Example
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Experimental Results
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Result Summary
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Achievements

• Demonstration of basic QoS functionality over
  BlueZ
• Dramatic improvement of performance
• Deep understanding of the Linux operating system

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Acknowledgments

• Internet
• http//www.palowireless.com
• http//sourceforge.net
• http//bluez.sourceforge.net
• http//www.bluetooth.org
• http//www.microsoft.com
• http//www.btdesigner.com
• Professional literature
• Bluetooth Revealed The Insider's Guide to an
  Open Specification for Global Wireless
  Communications by Brent A. Miller, Chatschik
  Bisdikian, Published by Prentice Hall PTR. August
  2000
• Bluetooth Demystified by Nathan J. Muller.
  Publisher McGraw-Hill Companies October 2000
• Bluetooth SIG Specs
• Quality of Service in Bluetooth Networking, By
  Martin van der Zee, Geert Heijenk
• Bluetooth 1.2 Flow specification and Flush
  Timeout, By Bluetooth SIG Radio Working Group QoS
  team

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