1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Merged DSSS Proposal for TG4g]
Date Submitted: [September 18, 2009]
Source: [Kuor Hsin Chang, Scott Weikel, Clint Powell, & Rick Enns, Seong-Soon Joo, Tae-Joon Park, Wun-Cheol Jeong, Jong-Suk Chae]
Company: [Elster Electricity, Consultants, ETRI]
Address: []
Voice: [KC: , SW: , CP: , RE: , SSJ: , TJP: , WCJ: , JSC: ]
Re: []
Abstract: Merged 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
<author>, <company>

2. Merged Proposal for DSSS to TG4g
<month year>
doc.: IEEE <doc#>
Merged Proposal for DSSS to TG4g
Merged proposals : ,
Kuor Hsin Chang1 , Scott Weikel1
Clint Powell2, Rick Enns2
Seong-Soon Joo3 , Tae-Joon Park3, Wun-Cheol Jeong3, Jong-Suk Chae3
Elster Electricity1, Consultant2, ETRI3
<author>, <company>

3. doc.: IEEE 802.15-<doc .....>
<May,2009>
doc.: IEEE <doc .....>
Agenda
Motivation
Proposed Solution
Flexible DSSS for 2.4GHz
Flexible DSSS for 900MHz
PPDU Format
Benefits
Compliance to the PAR
Benefits of Flexible DSSS
Summary and conclusions
<author>, <company>

4. Motivation Maintain compatibility to the legacy devices
Extend the existing PHY to serve the application in SUN network
Improve the existing PHY for outdoor communications
Keep principle of simple, low cost, low energy

5. Flexible DSSS for 2.4GHz (1)
Provide configuration options for the number of chips per symbol and bits per symbol while keeping the chip rate constant at 1Mcps/2Mcps
Optimize performance for range and data rate – long range at reduced data rate and short range at high data rate

6. Flexible DSSS for 2.4 GHz (2)
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
* Under Review

7. 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

8. 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

9. Flexible DSSS for 900MHz (1)
Improve the existing PHY for outdoor communications
Simple and reasonable approach to combat multipath fading
Adopt Constant Amplitude - Code Division Multiplex (CA-CDM)

10. Flexible DSSS for 900 MHz (2)
Chip rate (cps)
Chips per symbol
Bits per symbol
Data rate (bps)
Symbol duration
Notes
1 M
128 9
62.5 K
(70.3K)
128us
rural application 64
125 K
(140.6K)
64us 16 4
250 K
16us
IEEE
500 K
(562.5K)
Urban application

11. Spreading sequence for 64 chips per symbol (125/62.5 Kbps)
Data symbol
(decimal)
(binary)
(b0)
Chip values
(c0 c1 … c30 c331)
Note 1
PN Code 0/8 in Table 24
Data Rate of 250 kbps (900 MHz PHY in IEEE )
Spreading sequence for 16 chips per symbol(500Kbps)
Data symbol
(decimal)
(b0 b1 b2 b3)
Chip values
(c0 c1 … c14 c15)
Note
PN Code 0 in Table 37 ∙

12. PPDU Format Proposal
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)

13. Packet Length Field Maximum packet length of 2047 bytes.
Use Bit to determine data rate:
Bit 11-12 00 01 10 11
Data Rate (k bps)
62.5
125
250
500

14. Packet Length Field (cont’d.)
Bit 13: Parity Check bit for packet length to avoid unnecessary receiver power consumption due to errors in packet length
Bit 15:
0: Short Packet (Packet Length to be ≤ 127 bytes)
1: Long Packet (127 bytes < Packet Length ≤ 2047 bytes)

15. 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

16. Advantages of Making DSSS Flexible (1)
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.

17. Advantages of Making DSSS Flexible (2)
Mitigating the requirements for Power amplifier by reducing PAPR
Minimizing the performance loss due to the two-level conversion by exploiting odd-parity check encoded data
Long symbol duration (code (128,9))

18. Conclusions Merged proposal for flexible DSSS
Compatible to the existing PHY
Easy chip design – keeps the chip rate set at what uses.
Simple and reasonable solution for multipath fading

19. Backup

20. CA-CDM Transmitter
Block diagram of CA-CDM Transmitter

21. CA-CDM Transmitter
Odd-Parity Check Code Encoder

22. CA-CDM Transmitter Hadamard Modulation (Reed-Muller Encoding)
Symbol mapping

23. CA-CDM Transmitter
(16,4) Hadamard Spreading

24. CA-CDM Transmitter
Bitwise XOR

25. CA-CDM Receiver
CA-CDM Receiver Block Diagram

26. 62.5Kbps Simulation results in AWGN channel
CA-CDM in AWGN channel
(32,1) in AWGN channel

27. 62.5Kbps Simulation results in Rayleigh channel
CA-CDM in Rayleigh channel
(32,1) in Rayleigh channel

28. Summary of simulation results
In AWGN channel condition
CA-CDM shows 4.5 dB of improvement comparing to IEEE with (32,1) code
In Rayleigh Fading channel condition
CA-CDM shows 4.8 dB of improvement comparing to IEEE with (32,1) code