Inquiry and Paging for Bluetooth Piconet and Scatternet Formation in NS

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Inquiry and Paging for Bluetooth Piconet and
Scatternet Formation in NS

• Denis Perelyubskiy
• Vadim Olshansky
• Vitaliy Dykhne

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Project Overview

• Implementation of Bluetooth Inquiry and Paging
  procedures in ns-2 network simulator based on
  Bluetooth Standard version 1.0b/1.1

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Project Goals

• Implement Link Controller state machine
• Implement Frequency Hopping
• Simulate node discovery and connection setup to
  evaluate performance of Bluetooth technology in
  various scenarios

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Link Controller State Machine
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Accomplishments

• Done
• Frequency Hopping
• Inquiry Procedure
• Paging Procedure (pending resolution of several
  serious issues)
• Limited Performance Analysis of Inquiry Procedure
• 3000 lines of code

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Accomplishments (cont)

• Not Done
• Scatternet Formation
• Paging Procedure Performance Analysis

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Problems Encountered

• Our biggest problem is the standard
• General and vague
• Insufficiently precise on critical issues such as
  frequency hopping
• Changed recently

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Example of a specific problem

• Master needs to operate in both transmit and
  receive modes while waiting for an ID packet from
  the bluetooth slave
• In page mode the RX hops are selected according
  to the page_response hopping sequence (BT 1.1,
  3rd paragraph, page 98)
• X control input to the frequency hopping
  computation is Xprm CLKE16-12 Koffset
  (CLKE4-2,0-CLKE16-12) mod 16 Nmod32
• here, CLKE is the frozen clock, and k-offset
  is a frozen offset. The values are frozen when
  the slave ID packet is received (section
  11.3.3.2 of the BT 1.1 standard)

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Example of a specific problem(contd)

• Problem if the ID packet has not been received
  from the slave yet, we will not have frozen
  clock/offset values what do we do?

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Implications of the problem

• While we can compute some kind of hopping
  sequences for both nodes involved, it takes them
  a very long time to randezvous, which hints at
  the wrong values of inputs to the
  frequency-hopping function
• Using random sequences of some sort during
  connection establishment is difficult

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On a brighter side...

• We did implement and test the frequency hop
  computation
• validated using sample data at the end of the
  specification
• this means that our function works utilizing
  garbage-in-garbage-out principle given good
  inputs, it will produce proper output this
  means to fix 99 of our problems, we just need to
  clarify the inputs to the function at several
  controversial states.

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Some Simulation Results