A VLSI IMPLEMENTATION OF AN ADAPTIVE-EFFORT LOW-POWER VITERBI DECODER FOR WIRELESS COMMUNICATIONS A thesis submitted to the Department of Electrical and Computer Engineering in conformity with the requirements for the degree of Master of Science Queen's University Kingston, Ontario, Canada copyright Gordon John Allan, 2001
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A VLSI IMPLEMENTATION OF AN ADAPTIVE-EFFORT LOW-POWER VITERBI DECODER …gallan/pdf/adaptive_viterbi.pdf · 2003-03-10 · VITERBI DECODER FOR WIRELESS COMMUNICATIONS ... •A-RSSD
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A VLSI IMPLEMENTATION OF AN ADAPTIVE-EFFORT LOW-POWER
VITERBI DECODER FOR WIRELESS COMMUNICATIONS
A thesis submitted to the Department of Electrical and Computer Engineering
in conformity with the requirements forthe degree of Master of Science
Queen's UniversityKingston, Ontario, Canada
copyright Gordon John Allan, 2001
Cellular Systems• Interference based• Increasing capacity• Push towards data-centric apps
f0 f1
f0 f1f0
f0
CDMA
FDM
• Inc. speed/function à higher MIPS• Higher MIPS à low battery life
Plethora of Standards
A non-exhaustive list of international mobile standards
Peer Bluetooth North A.+ to Tetra Europe The Terrestrial Trunked Radio Peer PHS Japan Personal Handy System
AMPS North A. Advanced Mobile Phone System 1G TACS Europe Total Access Communications System
J-TACS Japan Japanese Total Access Communications System NMT Nordic Nordic Mobile Telephone CDMA North A. Code Division Multiple Access (IS-95 Standard)
2G GSM Europe Global System for Mobile communications PDC/JDC Japan Personal Digital Cellular/Japan Digital Cellular CDMAone North A. IS-95 B Standard
2.5G GPRS Europe General Packet Radio Service - GSM w/ packets Edge Europe Enhanced Data rates for Global Evolution (384 kbps) cdma2000 North A. also known as Wideband CDMA
3G UMTS Europe Universal Mobile Telecommunications System NTT DoCoMo Japan
• Many different Wireless standards• Currently have 2.5G[eneration] networks available
Error Correcting Codes (ECC)•Wireless channel is quite harsh
•Use convolutional codes to protect ‘important’ data
•Strength of the code is mainly determined by its constraint length (K=9 in 3G below)
•Power hungry to decode – especially at high data rates
Effect of Constraint Length on Error Rate
Current Solutions• Current solutions implement the Viterbi algorithm on a DSP for the