doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> CSS PHY overview, Sept 05 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [CSS PHY overview, Sept 05] Date Submitted: [23 September 2005] Source: Rainer Hach Company: Nanotron Technologies Address: Alt-Moabit 61, 10555 Berlin, Germany Voice: +49 30 399 954 207 E-Mail: r.hach@nanotron.com Re: [] Abstract: [ ] Purpose: [] Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15. Hach, Nanotron <author>, <company>

TOC Key parameters Biorthogonal code performance CSS PHY overview, Sept 05 TOC Key parameters Biorthogonal code performance How do we achieve our objectives? Open questions What are the next steps ? Hach, Nanotron

Key parameters CSS PHY overview, Sept 05 Chirp spread spectrum (CSS) combined with differential phase shift keying (DPSK) Four subchirps form one chirp symbol Four sequences of subchirps form a set of four chirp symbols (equivalent to four codes) Chirp symbols are separeted by time gaps of alternating duration Average chirp symbol rate is 1/6μs For DBPSK: 1 bit per subchirp -> 4 bits per chirp symbol For DQPSK: 2 bits per subchirp -> 8 bits per chirp symbol DBPSK is used for aquisition (SHR) DQPSK with biorthognal coding is used for data communication Two biorthogonal codes yield two data rates Code rate 3/4 -> 3/4 * 8 bit / 6μs = 1 Mbit/s Code rate 6/32 -> 6/32 * 8 bit / 6μs = 250 kBit/s Tx Power range similiar to 15.4-2003, 2.4GHz 6 dB bandwidth is 14 MHz Frequency channel scheme from 11b (5MHz spacing) is utilized Frequency devision, code devision or combinations of both can be used for separation of piconets Hach, Nanotron

Biorthogonal code performance CSS PHY overview, Sept 05 Biorthogonal code performance see 15-05-0554-01-004a Hach, Nanotron

CSS PHY overview, Sept 05 How do we achieve our objectives ? (Extended range and robustness in comparison with 15.4-2003 ) By using more bandwidth and flat spectrum signal (chirp) less fading margin needs to be provided doc.: 15-04-0227-03-004A, slide 16 : fading margin is dependent on bandwidth UWB: 5 dB 802.11a/b: 8 dB 802.15.4: 16 dB Combination of CSS with differential modulation efficiently addresses distortion caused by multipath channel Additional coding gain by biorthogonal code Higher data rate results in shorter packet duration Hach, Nanotron

CSS PHY overview, Sept 05 Open questions Timing adjustment with respect to sampling rate implementations Hach, Nanotron

Next steps Address open questions CSS PHY overview, Sept 05 Next steps Address open questions Continue work on Coexistence Assurance Model 15.1 (dwell time, packet length) Derive formula or table for BER computation Address 11g Validate assumptions on spectral masks and input filter bandwidth of victim systems Check and validate complete CSS PHY Hach, Nanotron