Wireless Network Processors

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Wireless Network Processors

• Presented by
• Krishna K
• 2002EEC001

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Overview of the presentation

• Networking
• Requirement of network-processor
• Wireless processors
• Design methodology
• Case study
• Reference

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Networking
Wired Routers,switches,etc..
Wireless
Wifi 2.4 GHz,100 mts, 11 mbps
Blue Tooth 2.4 GHz,10 mts, 850 kbps
Mobile phones 2.5G and 3G
Access point
Sensor network 900 Mhz
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Networking..
physical ?transceiver, modem link/MAC ? packet
scheduling routing ?routing protocols transport
? TCP application ? adaptive buffering
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Requirement of network - processor

• Speed
• Power
• Size
• Less time for the design ( Due to market pressure
  )
• Bit level processing ( MAC Layer )
• Flexible to Implement the Algorithms
• RFdesign issue
• Complete integration of all layers of a networked
  node on a single chip
• Protocol communication functions are central to
  chip functionality
• Multimedia ( Mobile phones .. Emerging !!!)

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Design methodology

• General purpose High performance processor (cost,
  size power )
• ASIC ( time constrain )
• ASIPs
• Perform task _at_ wire speed
• Flexible
• Time to market
• Use highly reusable architecture.

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Wireless Network Processor Chip
Access point
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Design methodology (cont..)

• Platform-based design
• Facilitates design reuse
• The hardware platform
• Flexible (parameterizable) architecture that
  support the functions in the application space.
• The software platform
• Abstract the hardware platform to programmers
  model (allow effective mapping ).
• System platform hardware software platform.

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Design methodology (cont..)
Architectures Space
Select System Platform
Application Space
Design exploration with in System Platform
Best mapping of Application to Architecture
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Design methodology (cont..)
Phase I
Phase II
Phase III
Configurable Platform
Functional Spec..
Key operations Functional profiling
Implementation
Mapping
Reconfigurable Fabric exploration
Performance evaluation
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Platform Conception( Phase I )

• Conceive a system platform
• Identifies a set of architectural modules to
  support class of functions in applications
  domain.
• Platform for wireless systems consist of
• Programmable processor
• Configurable logic
• Dedicated logic
• Memories
• Peripherals
• Construct hardware platform that support key
  functions
• Identify key functions and its constrains (
  functional profiling )
• Explore the available architectural module
  behavior ( architecture exploration )
• Define System Platform

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Platform Instantiation ( Phase II )

• Explore with in the system platform
• Find platform instance suitable for given set of
  application
• Evaluate performance of the platform with
  functional constraints
• Need for a purely functional specification

• With available lib of architectural modules
• Performance
• Energy
• Area prediction modules

• Construct different platform with varying
  performance for our application

Get optimal performance instance
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Implementation ( Phase III )
With available platform that meets all design
constrains
Hardware
Application
Mapping is a Software Issue
Application code generation, RTOs, Design
synthesis
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Case Study PicoRadio

• ad hoc sensor based networks has several
  programmable and self organizing radios.
• For data acquisition and environmental control
  applications
• Need extremely low energy consumption
• Size
• Cost

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Case Study (cont..)

• Functional profiling
• Explore regularity
• Extract common operations in the application
• Profiling granularity Classification
  Interpretation of the collected data.
• Granularity is too coarse or too fine
• Insertion of the wrapper functions are needed
• List of critical operations
• Parsing
• Searching ( table look )
• Packet modifying and reassembly

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Case Study (cont..)

• Functional profiling
• Studied four different scenarios with two
  different protocols
• ( AODV ) Ad-hoc On-Demand Distance Vector
  Routing Reactive protocol
• ( DSDV ) Dynamic Destination Sequenced Distance
  Vector Routing Proactive protocol
• Uniform Uniform grid of nodes in which neighbor
  can hear each other
• Random randomly generated distribution
  generate less traffic

• Searching 20 to 45 of total time
• Prasing,modification, re-assembly etc.. Consume
  18 28 of total time.

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• Architecture Exploration
• Wireless platform must provide some degree of
  programmability.
• FPGA
• PLD
• Microprocessor ( Fail in energy requirement )
• Protocol design specified using
• Extended FSM models ( FSM Data Path )
• Exhibits highly irregular logic structure
• FSM directly maps to two level logic
• FSM has very wide input less out puts
• FPGA tends to be more suitable for data path
  element.
• PLD for efficient FSM implementation

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Architecture Exploration
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Reference

• Challenges and opportunities in broadband and
  wireless communication designsRabaey, J.M.
  Potkonjak, M. Koushanfar, F. Suet-Fei Li Tuan,
  T.Computer Aided Design, 2000. ICCAD-2000.
  IEEE/ACM International Conference on , 5-9 Nov.
  2000 Pages76 82
• http//www.ics.uci.edu/iesag
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