1. May 2009
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Flexible DSSS Proposal]
Date Submitted: [01 March 2009]
Source: [Kuor Hsin Chang, Clint Powell, & Rick Enns] Company [Freescale & Consultant]
Address [KC: 890 N. McCarthy Blvd, Suite 120, Milpitas, CA USA]
Voice:[KC:+1 (408) , RE: ]
Re: []
Abstract: Proposal for a radio based on a flexible DSSS
Purpose: Presented to the g SUN Task Group for consideration
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

2. Flexible Direct Sequence Spread Spectrum (DSSS) Proposal
May 2009
Flexible Direct Sequence Spread Spectrum (DSSS) Proposal
Kuor Hsin Chang - Freescale
Clint Powell - Consultant
Rick Enns - Consultant
May, 2009 at Montreal CA

3. Flexible DSSS Proposal
May 2009
Flexible DSSS Proposal
Provide configuration options for the number of chips per symbol and bits per symbol while keeping the chip rate constant at 2 Mcps
Optimize performance for range and data rate – long range at reduced data rate and short range at high data rate

4. Flexible DSSS Examples for 2.4 GHz
May 2009
Flexible DSSS Examples for 2.4 GHz
Chip rate (cps)
Chips per symbol
Bits per symbol
Data rate (bps)
Coding gain (dB)
Notes
2 M 32 1
62.5 K
15.05
rural application 2
125 K
12.04 4
250 K
9.03 16
500 K
6.02
Urban application

5. PN Codes & Chip to Symbol Mapping:
Data Rate of 62.5 kbps
Data Rate of 125 kbps
Data Rate of 250 kbps (2.4 GHz PHY in IEEE )
Data symbol
(decimal)
(binary)
(b0)
Chip values
(c0 c1 … c30 c331)
Note
PN Code 0 in Table 24 1
PN Code 8 in Table 24
Data symbol
(decimal)
(binary)
(b0 b1)
Chip values
(c0 c1 … c30 c331)
Note 00
PN Code 0 in Table 24 1 10
PN Code 4 in Table 24 2 01
PN Code 8 in Table 24 3 11
PN Code 12 in Table 24

6. PN Codes & Chip to Symbol Mapping (cont’d.)
Data Rate of 500 kbps
Data symbol
(decimal)
(b0 b1 b2 b3)
Chip values
(c0 c1 … c14 c15) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

7. Packet Structure
Extend the Frame Length Field (PHR) of packet from one byte to two bytes in order to support the packet length to be up to 1500 bytes.
Use bit 15 (bit 7 of the Frame Control Field) of the PHR to determine long packet (≥127 bytes) or short packet (≤127 bytes)

8. Packet Length Field Maximum packet length of 2047 bytes.
Parity Check bit for packet length to avoid unnecessary receiver power consumption due to errors in packet length

9. Compliance to the PAR PAR requirement Comments
May 2009
Compliance to the PAR
PAR requirement
Comments
Operation in license exempt bands 
DSSS can be applied to the radios for the 868/915/2.4 GHz bands
Data rate between 40 and 1,000 kbps
Adjustable data rates available in this range
Optimal link margins for rural and urban environments
Coding trades off data rate for range
Principally outdoor
Basic radio proven
1500 octet frame size
An extension to the radio synchronization
At least 3 co-located networks
Supported
At least 1,000 neighbors

10. Advantages of Making DSSS Flexible
May 2009
Advantages of Making DSSS Flexible
Easy chip design – keeps the chip rate set at what uses. The design of the front end of the current chips can be used.
Simple- we know the radio and this is well understood extension to only the digital side.
Known coexistence properties – transmissions look the same to other radios.