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This submission in January 2006 from Freescale Semiconductor provides a framework for revising baseline drafts for WPANs. It covers regulatory flexibility, coexistence, scalable performance, precision ranging, and more.
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Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [TG4a General Framework] Date Submitted: [January 2006] Source: [Matt Welborn] Company [Freescale Semiconductor, Inc] Address [8133 Leesburg Pike Vienna, VA USA] Voice:[703-269-3000], E-Mail:[matt.welborn @freescale.com] Re: [] Abstract: [] Purpose: [Provide framework for revision baseline draft] Notice: This document has been prepared to assist the IEEE 802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by 802.15.
TG4a Overview • Responsive to PAR: Low complexity & power with precision ranging • Regulatory flexibility: Multiple bands in different band groups tailored to expected regulations around the world • Coexistence: Low PSD + low duty cycle + multiple bands + other features • Scalable performance vs. complexity
Baseline Mode – Low Complexity with Robust Performance in Multipath • Single UWB band centered at ~4 GHz • Fc = 3993.6 MHz (based on 499.2 MHz band spacing) • Hybrid PPM+BPSK modulation • Default preamble • 256 symbols of L=31 perfect ternary sequence • Data rate: 851 kbps • Concatenated code • Systematic RS + Systematic convolutional code • Very low complexity Aloha medium access control • Ideal for low duty cycle UWB waveforms • Wide bandwidth (>500 MHz) for precision ranging
Spectrum Usage • Provides flexibility for coexistence and regulatory compliance worldwide • 4 band groups • 1: 3.1 to 4.8 GHz • 2: 6 to 10.6 GHz • 3: 2.4 ISM band (non-UWB requires different modulation) • 4: 500 MHz • One or more designated operating frequencies within each band group • Each band group has a single mandatory band to minimize complexity but ensure interoperability
Modulation and FEC • Extremely low complexity architectures are supported for key applications • Hybrid design to provide scalable complexity and performance • Combined PPM and convolutional coding to support coherent and non-coherent architectures • Provides robust performance even in extreme multipath environments • Systematic FEC codes to allow flexible decoding implementation
Pulse Shaping • Pulse-based UWB technology allows the use of • Latitude in pulse shape allow implementation to optimize for different issues: • Control spectrum • Improve performance in different areas • Minimize complexity • Baseline pulse is specified • Additional optional modifications are identified • Composite pulse based on linear combination • Chirp & CS intended to reduce cross-correlation • Phase incoherent pulse [was “chaos”]
Precision Ranging • Precision ranging capability is provided • MAC layer support: • PHY layer support: variable preamble lengths provided to support channel estimation and multipath correction • Ranging protocols
Scalability • Extreme multipath conditions • Reduced PRF for operation in extreme channels • High density deployments • Multiple codes per operating band • Time dithering for piconet isolation • High processing gain for isolation • Alternate symbol rates to trade off robustness and channel duty cycle