1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
CSS PHY overview, Sept 05
Project: IEEE P 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, Berlin, Germany
Voice:
Re: []
Abstract: [ ]
Purpose: []
Notice: This document has been prepared to assist the IEEE P 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 P
Hach, Nanotron
<author>, <company>

2. 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

3. 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 , 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

4. Biorthogonal code performance
CSS PHY overview, Sept 05
Biorthogonal code performance
see a
Hach, Nanotron

5. CSS PHY overview, Sept 05
How do we achieve our objectives ? (Extended range and robustness in comparison with )
By using more bandwidth and flat spectrum signal (chirp) less fading margin needs to be provided
doc.: A, slide 16 :
fading margin is dependent on bandwidth
UWB: 5 dB
802.11a/b: 8 dB
: 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

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

7. 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