Modeling%20a%20Multicarrier%20Wireless%20Communication%20Transceiver

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Modeling a Multicarrier Wireless Communication
Transceiver

• Embedded Software Systems
• Literature Survey
• March 24,2004

By Hunaid Lotia
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Overview

• Multicarrier Modulation
• Motivation
• Existing Research
• OFDM (Orthogonal Frequency Division Multiplexing)
• Goals
• Questions

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Multicarrier Modulation

• Technique in which multiple frequencies are used
  to transmit data
• Divide broadband channel into narrowband sub
  channels
• Widely used in ADSL and wireless LAN

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Motivation for Multicarrier Modulation

• Applications requiring high rate data
  transmission.
• Increasing power of Digital Signal Processing
  tools. (1960s)
• Applications range from Digital Audio and Video
  Broadcasting to High-Speed Wireless LANs.

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Existing Work and Research

• Most common candidates for Multicarrier Wireless
  (Mobile) Communication are
• Direct Sequence Code Division Multiple Access
  (DS-CDMA)- Receiver Complexity
• Frequency Hopping-CDMA (FH-CDMA)- Requires
  powerful channel coding to mitigate fading
  effects.
• Solution OFDM Transmission System
• Considered for fourth-generation mobile
  communication systems.

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An OFDM Modem
N subchannels
N complex samples
S/P
quadrature amplitude modulation (QAM) encoder
N-length Inverse FFT
add cyclic prefix
P/S
D/A transmit filter
Bits
TRANSMITTER
multipath channel
RECEIVER
N complex samples
N subchannels
Receive filter A/D
P/S
QAM decoder
N-length FFT
S/P
remove cyclic prefix
invert channel frequency domain equalizer
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Project Goals

• Model the OFDM system in Synchronous Dataflow
  (SDF)
• All nodes produce and consume fixed number of
  tokens
• Use SDF domain in Ptolemy to verify the model
• Investigate other open issues that come up as the
  projects builds up

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QUESTIONS?