bluetooth link performance with crc measurement n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
BLUETOOTH LINK PERFORMANCE WITH CRC MEASUREMENT PowerPoint Presentation
Download Presentation
BLUETOOTH LINK PERFORMANCE WITH CRC MEASUREMENT

Loading in 2 Seconds...

play fullscreen
1 / 21

BLUETOOTH LINK PERFORMANCE WITH CRC MEASUREMENT - PowerPoint PPT Presentation


  • 127 Views
  • Uploaded on

BLUETOOTH LINK PERFORMANCE WITH CRC MEASUREMENT. CS 215 CLASS PROJECT by Lingtao Cao Wenfei Feng Howie Yu March 22, 2001. OVERVIEW. Introduction Problem Statement and Scope of Work Bluetooth Error Correction CRC Calculation Algorithm Glomosim CRC Implementation Simulation Summary

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'BLUETOOTH LINK PERFORMANCE WITH CRC MEASUREMENT' - radley


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
bluetooth link performance with crc measurement
BLUETOOTH LINK PERFORMANCE WITH CRC MEASUREMENT

CS 215 CLASS PROJECT

by

Lingtao Cao

Wenfei Feng

Howie Yu

March 22, 2001

overview
OVERVIEW
  • Introduction
  • Problem Statement and Scope of Work
  • Bluetooth Error Correction
  • CRC Calculation Algorithm
  • Glomosim CRC Implementation
  • Simulation
  • Summary
  • Future work
introduction
INTRODUCTION
  • Wireless Technology
  • Low cost
  • low power
  • no line of sight
  • Data/Voice, Personal ad hoc networks
  • wide industry support
  • Piconet and scatternet
problem and scope of work
PROBLEM AND SCOPE OF WORK
  • PROBLEM STATEMENT
    • Relatively new technology, Lots of research needs to be done
    • Bluetooth Link Performance and Modeling
      • Link performance parameters
        • PDP (packet dropping probability)
        • PEP (packet error probability)
      • Bluetooth Error Detection and Correction
    • Present Simulator (Glomosim) does not enable error detection and correction
problem and scope of work1
PROBLEM AND SCOPE OF WORK
  • SCOPE OF WORK
    • Study Bluetooth Specification
    • Error Correction Techniques and Algorithms
    • Familiarize Glomosim
    • Implement CRC Error detection and Correction in Glomosim
    • Run Simulation and Study the Link Performance
bluetooth error correction
BLUETOOTH ERROR CORRECTION

BLUETOOTH PACKET FORMAT

payload format
PAYLOAD FORMAT
  • Component:
    • payload header
    • payload body
    • CRC code
error corretion in bluetooth
ERROR CORRETION IN BLUETOOTH
  • 1/3 Rate FEC
  • 2/3 Rate FEC
  • CRC-ARQ Scheme
crc calculation algorithm
CRC CALCULATION ALGORITHM
  • GENERAL ERROR CORRETION TECHNIQUES
    • GOAL
      • Enable the receiver of a message transmitted through a noisy (error-introducing) channel to determine whether the message has been corrupted.
    • HOW
      • Transmitter constructs a value (called a checksum) that is a function of the message, and appends it to the message.
      • The receiver can then use the same function to calculate the checksum of the received message and compare it with the appended checksum to see if the message was correctly received.
    • COMPLEXITY
      • Increase CRC bits would strengthen CRC checksum
crc calculation algorithm1
CRC CALCULATION ALGORITHM
  • FUNCTION
    • WIDTH: A register width wide enough to provide a low a-priori probability of failure (e.g. 32-bits gives a 1/2^32 chance of failure)
    • CHAOS: A formula that gives each input byte the potential to change any number of bits in the register.
  • BASIC IDEA
    • treat the message as an enormous binary number, to divide it by another fixed binary number, and to make the remainder from this division the checksum.
    • Upon receipt of the message, the receiver can perform the same division and compare the remainder with the "checksum" (transmitted remainder).
cyclic redundancy check crc
Cyclic Redundancy Check (CRC)
  • Purpose: calculate R (CRC bits) to detect “error” (e.g., flipped bits) in transmitted segment
  • Parameters:
    • G: 1 + the upper 8 bits of the physical address of the master
    • D: data bits to be sent (payload, header)
    • r: number of CRC bits (16 bits for payload, 8 bits for HEC)
slide14

CRC Example

  • Want:
    • D.2^r XOR R = G
  • equivalently:
    • D.2^r = G XOR R
  • equivalently:
  • if we divide D.2r by G, want reminder R

D.2^r

G

R = remainder[ ]

simulation
SIMULATION
  • SIMULATION PARAMETERS
    • Number of Piconets = 1, 2, 3, 4
    • Number of Nodes = 8, 16, 24, 32
    • Simulation Time = 60 s
    • Source rate = 0.08 s
    • Channel Noise Figure = { 10.0 , 5.0, 0.0}
analysis of results
Analysis of Results
  • Execution without CRC
  • Influence of CRC Checking
  • Execution with CRC
    • Stability of the simulation environment
      • noise factors (radio and propagation ambient)
      • bandwidths (30, 185, 340)
    • Time effects with the increasing number of nodes/Piconets
    • Tradeoff between time consuming and error detection
    • It is feasible to add the CRC checking into the simulation when handling relative large number of nodes/Piconets
summary
SUMMARY
  • Error detection and correction will generally help to increase Bluetooth link performance
  • For light and uncrowded traffic, CRC does not improve the performance by much
  • Link performance decrease with increased source access rate even with CRC correction
future work
FUTURE WORK
  • Increase the number of Piconets and total number of nodes
  • Implement FEC encoding and decoding in Glomosim
  • Implement 3-State Model in Glomosim