1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Flexible DSSS Proposal for China Frequency Band]
Date Submitted: [5 July, 2009]
Source: [Y X Fu, J Shen, X Wang, Haituo Liu, L Li, Z Zhao, Z.F Zhao] Company [SIMIT, Vinno, JiaXing Wireless Sensor Networks Engineering Center, Huawei]
Address [NO.865 Changning Road, Shanghai, , China]
Voice:[ ], FAX:[ ], [ ]
Re: [IEEE g group]
Abstract: According to the regular limitation of frequency in China Smart Grid. A proposal of Flexible DSSS PHY layer on MHz to meet the requirement and characteristic.
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
FX. Fu, J.Shen Liang Li
<author>, <company>

2. Flexible DSSS Proposal for China Frequency Band
<month year>
doc.: IEEE <doc#>
June. 2009
Flexible DSSS Proposal for China Frequency Band
FX. Fu, J.Shen , Liang Li
<author>, <company>

3. 779-787MHz Regular Limit in China
<month year>
doc.: IEEE <doc#>
June. 2009
MHz Regular Limit in China
Max TX Power = 10mW (EIRP)
No occupied bandwidth requirement
Spurious emission is no larger than -36dBm
FX. Fu, J.Shen
<author>, <company>

4. Support the DSSS Modulation at 779-787MHz
<month year>
doc.: IEEE <doc#>
June. 2009
Support the DSSS Modulation at MHz
MHz is officially assigned for Wireless Control Application (Ptx< 10mW) and adopted in CWPAN std and 15.4c Std. In CWPAN and 15.4c std, for DSSS modulation, the BW (channel) is defined as BW=2MHz.
Support the DSSS modulation on 780MHz Bands for its tech advantages and it is widely adopted in WPAN, Zigbee and more applications.
However, bandwidth of each channel may be modified for new spec
FX. Fu, J.Shen
<author>, <company>

5. Why Flexible DSSS Special circumstances Flexible DSSS Benefits
P2P distance cover from 10m~1km
Limited TX power : 10mW
Flexible DSSS can get an additional trade-off process gain to meet both ends
Flexible DSSS Benefits
Adapt to transmitting circumstance easily
Variable PN length
M-ary spread spectrum
Easy to schedule
BW unchanged
Robust
Anti-multipath fading

6. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Channel spacing
Eight channels are available across 780MHz band
Independent channels are used to support simultaneous operation for at least 3 co-located orthogonal networks and avoid inner interferences of the network
Independent channels provide more choice when there is a interference
Fc = k in megahertz, for k = 0,…7
FX. Fu, J.Shen
<author>, <company>

7. General Description of the System
<month year>
doc.: IEEE <doc#>
June. 2009
General Description of the System
Modulation
O-QPSK or MPSK
Spreading
Spreading gain from 0~18dB
Channel Coding and Interleave(option)
To support the long frame requirements
½ rate convolution code
CRC
CRC-16 for short frame
CRC-32 for long frame
FX. Fu, J.Shen
<author>, <company>

8. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Flexible Spreading
Spread SHR and PHR with the a fixed PN sequence set by the MAC(usually the largest one)
Spread PPDU data with variable PN sequence, the pattern indicator of which is stated in PHR
FX. Fu, J.Shen
<author>, <company>

9. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Flexible Spreading
Normally, use 64 PN length as spreading factor at the preamble+SFD+PHR field
FX. Fu, J.Shen
<author>, <company>

10. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Flexible Spreading
Large gain at the SHR and PHR can
make sure of the system synchronization
protect the important field of SFD and PHR
The same PN sequence at the preamble and SFD and PHR field to all the devices in a domain can
be used as the fair judgment in measuring RSSI
Inform the existence of a signal to all devices
reduce the complexity of catch block design at the receiver
FX. Fu, J.Shen
<author>, <company>

11. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Flexible Spreading
On-time adjustment of spreading pattern by the indicator in PHR field can
Choose the suitable pattern to transmit signals directly without handshake through the MAC
Reduce the involvement of MAC in handling the adjustment of transmit signals
Gain the benefit of the optimal energy efficient link margin given the environmental conditions encountered in Smart Metering deployments with less cost
FX. Fu, J.Shen
<author>, <company>

12. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Spreading Mode
Mode
Chip rate
(cps)
Chips per Symbol
Bits per Symbol
Bit rate
(bps)
Gain(dB)
Note
500k 1 16 4
125k
6.02 2 32
62.5k
9,03 3
31.25k
12.04
15.62k
15.05 5 64
7.81k
18.06
FX. Fu, J.Shen
<author>, <company>

13. Spreading Code and Preamble Design
<month year>
doc.: IEEE <doc#>
June. 2009
Spreading Code and Preamble Design
Spreading Code
16-ary PN codes defined in IEEE C for OQPSK and MPSK
32-ary PN codes defined in IEEE
Preamble Design
Preamble is mainly used to catch the frame, thus it should guarantee it could accumulate the higher SIR than all the PHY payload
To the option PN code, which is too long, to reduce the complexity of catching filter design, different preamble can be taken
FX. Fu, J.Shen
<author>, <company>

14. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Pulse Shape Filter
Raised cosine pulse shape with roll-off factor of r = 0.8
Employed in c
FX. Fu, J.Shen
<author>, <company>

15. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
PPDU Format
Octets: variable 2 1
variable
Bits: variable 16 7 4 3
Preamble
SFD
Frame Length
Extended
Length
Upper
Extended Address
Pattern Indicator
Parity Check
PSDU
Includes FCS
SHR
PHR
PHY Payload
The length of preamble is variable
Frame Length + Extended Length + Upper Extended Address stand for the possible whole frame length required in the PAR
Pattern Indicator indicates which PN code should be used
PHY Payload Spread with the PN code indicated by indication factor
FX. Fu, J.Shen
<author>, <company>

16. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
New PHY PIB attributes
phyTransmitMode
To inform Flexible DSSS transmit mode selection
Type: Integer
Value: 0-7
FX. Fu, J.Shen
<author>, <company>

17. Support from Physical Layer Sum Up
<month year>
doc.: IEEE <doc#>
June. 2009
Support from Physical Layer Sum Up
Frequency adjustment
There are 8 channels under the adjustment of MAC, and MAC can assign the right channel to a device to make the network run more efficiency
Different spreading pattern adjustment
MAC can change spreading pattern through PHY PIB
FX. Fu, J.Shen
<author>, <company>

18. Support from Physical Layer Sum Up
<month year>
doc.: IEEE <doc#>
June. 2009
Support from Physical Layer Sum Up
Channel Listening support
The PN code is the same at the frame head, thus all the devices can hear it and get to know that a signal is to be transmitted, and the last time of the frame is also known
The RSSI can be measured through the frame head, which is the same to all nodes
FX. Fu, J.Shen
<author>, <company>

19. Support from Physical Layer Sum Up
<month year>
doc.: IEEE <doc#>
June. 2009
Support from Physical Layer Sum Up
Inner PN CSMA support
When the longest PN code is applied, the phase shift can be used to support multi-user
When a device has a data to send, while it heard the preamble of another device, it can carefully choose the phase shift and control its send power to send at almost the same time
Be useful especially when the destination device is the same
FX. Fu, J.Shen
<author>, <company>

20. Consideration with Existing MAC (Beacon)
<month year>
doc.: IEEE <doc#>
June. 2009
Consideration with Existing MAC (Beacon)
Slotted CAP: Since all the frame head use the same PN code, listening to the PN code of the frame head at the beginning of the slot will avoid the conflicts
The device pair can judge which mode is best for transmission after the short conversation at CAP field, and they can keep the result for a period of a time (which could be set according to the mobility of the network).
At CFP field, the device can use the judge result from the CAP field to transmit signals.
FX. Fu, J.Shen
<author>, <company>

21. Consideration with Existing MAC (Non-beacon)
<month year>
doc.: IEEE <doc#>
June. 2009
Consideration with Existing MAC (Non-beacon)
To the non-beacon enable case, it is suggested that the PHY payload field use the same PN code as the preamble.
If different PN code is used in preamble and the PHY payload field, the device should be able to detect all the PN code, or it should listen for quite a long time which could make sure the preamble should have appeared in case there is one
Inner PN CSMA can be applied to expand the system capability
FX. Fu, J.Shen
<author>, <company>

22. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
June. 2009
Thank you
FX. Fu, J.Shen
<author>, <company>