Bluetooth Connection Establishment Process semester II

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Bluetooth Connection Establishment
Processsemester II
Miki Asa Gur Hildesheim Instructor Ronen Kofman
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Project Goals

• Simulate the inquiry and inquiry scan
  processes.
• Study the existing algorithms that regard BT
  connection establishment process by reading
  relevant papers.
• Develop a new algorithm, which have some
  advantage over the existing algorithms.
• Simulate our algorithm and compare its
  performance to the existing algorithms.

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Connection Establishment

• Inquiry
• The master is transmitting its ID on different
  frequencies and listening alternately.
• Inquiry scan
• The slave listening on a single frequency.
• Once hearing the master go to sleep for 0 ,
  1023 slots.
• Wakes up and response to the master by providing
  information about his clock and ID (BD_ADDR) for
  the page process.

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The subnet

• The masters are looking for slaves

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The node model

• The algorithm decides to which mode to enter.
• The bt_modes implement the algorithm request.
• The receiver and transmitter deal with the radio
  packets from/to bt_modes.

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The process model (cont)
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Scenario

• Two units wants to connect and do not care who
  is the master and who is the slave.
• For example
• Laptops, PDA, Cellular phones . . .

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The known algorithm (cont.)

• The units must toggle between inquiry and inquiry
  scan.
• Each unit randomly choose a period of time to be
  master/slave.
• The period of time must be randomly chosen, but
  we can determine the mean time for state
  residence.

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The known algorithm (cont.)

• We study Salonidis paper about these periods of
  time where he investigated there influence on the
  connection time of two units.
• Salonidis claimed that the units should be on
  inquiry and inquiry scan for an average period of
  0.4 - 0.6 sec.
• We simulated the algorithm with different values
  for the mean time state residence and received
  the same results as in the paper.

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The known algorithm (cont.)

• the best mean time is 0.4-0.6 seconds, causing an
  average delay of 1 second for the connection
  establishment.

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Our results
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The problem

• The 32 frequencies of BT are divided into two
  trains A train B train.
• The algorithm assume that all the 32 hops
  transmitted sequentially.
• According to the spec, train A (16 hops) is
  transmitted 256 times and then train B (the other
  16 hops) is transmitted for 256 times.
• Therefore if the units transmit/listen on
  different trains they wont connect until one of
  them will switch train.

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The problem (cont.)

• We simulated the algorithm with the correct
  conditions

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Our algorithm

• While (no connection)
• Enter for 16 slots for Inquiry scan.
• upon (packet arrival)
• remain on inquiry scan for the sleeping
  phase wake up for 32
  slots.
• upon (packet arrival)
• announce the other unit and go to page scan.
• Randomly choose a period of time for Inquiry
• upon (packet arrival)
• go to page.

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Our algorithm
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Advantages

• Each unit spend most of its time on inquiry.
• Less time to switch trains.
• Each unit that turn on starts with inquiry scan,
  therefore has a higher probability to find a
  master.
• Inquiry scan process performed only for 16 slots
• enough time to scan the whole hop sequence.

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Performance

• It is obviously that the connection establishment
  time depend on the time the units enter for
  inquiry.
• This period of time is randomize with a certain
  mean time.
• Question
• What is the best average mean time to be in
  inquiry?

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What is the best average mean time to be in
inquiry?

• Connection time 119710112/T9/32T

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What is the best average mean time to be in
inquiry?
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Future work

• Check the algorithms performance under different
  condition
• Both units are already awaken and enter each
  other range (units on the move).
• One of the units is with our algorithm and the
  other unit with the known algorithm.
• Writing a paper