1. <month year>
IEEE P xxxx g
July 2009
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Narrow Band Frequency Hopping PHY Proposal for g]
Date Submitted: [July 2009]
Source (in no particular order):
[Michael Schmidt, Dietmar Eggert] Company [Atmel]
[Jeritt Kent] Company [Analog Devices]
[Cristina Seibert, George Flammer] Company [Silver Spring Networks]
Address [] Voice []
silverspringnet.com]
Re: []
Abstract: Detailed Proposal for a Narrow Band Frequency Hopping PHY for g
Purpose: Technical Proposal
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
Atmel, ADI, Silver Spring Networks
<author>, <company>

2. Overview of NBFH PHY Proposal
<month year>
IEEE P xxxx g
July 2009
Overview of NBFH PHY Proposal
SUN Characteristics
PHY Proposal Highlights
Normative PHY Specification
MAC Support
Conclusions
Atmel, ADI, Silver Spring Networks
<author>, <company>

3. Key Characteristics of SUN
July 2009
Key Characteristics of SUN
Low data rate: over the air data rates of 40 kbps up to 1 Mbps
Robust, proven techniques critical
Spectral efficiency desirable but not critical
Dynamic scaling to very large aggregate networks
Networks with millions of arbitrarily co-located nodes
Requirement for cost effective deployments
Interference mitigation capability
Peer to Peer, minimal infrastructure-dependent operation
PHY techniques suitable for packet forwarding and with minimal added interference
Enhanced IP support (> 1500 octet payload)
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4. PHY Proposal Highlights
July 2009
PHY Proposal Highlights
Parameter
NBFH-PHY
Operating band
sub- GHz (e.g. 902 MHz), 2.4GHz
Channel BW
< dB down from peak, others optional
Channel spacing
300 kHz, others optional
Modulation
MFSK required, GMSK,GFSK optional
FEC
Not required (optional)
Frequency Hopping
MAC controlled
PHY frame structure:
MAX payload
2047 octets
SHR
At least 32 bits preamble + 16 bit SFD
CRC
CRC-32
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5. PHY Proposal Highlights (Cont’d)
July 2009
Parameter
NBFH-PHY
Data Whitening
8-bit LFSR, variable seed
Data rate(s)
100 kbps, others optional
Symbol / chip rate
100 ksps, others optional
Transmit Power
As allowed by regulatory regimes
PSD
TX Power Control
Yes
Chan availability, blacklisting
MAC or higher layer defined
Link Quality
RSSI
Reliability enhancing features/methods
Hopping, CRC-32, scrambling
Co-existence features
Channel diversity, LDC, TPC
Co-located network support
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6. Benefit of Channel Diversity
July 2009
Benefit of Channel Diversity
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7. NBFH with FSK Modulation
<month year>
IEEE P xxxx g
July 2009
NBFH with FSK Modulation
Advantages:
Many channels => good interference mitigation
Constant envelope signal => inexpensive and low power PAs, receive/transmit chains
Does not rely on high precision clocks and sharp filters => low cost
Low to moderate SUN data rates => long symbol time => low ISI, low processing requirements
Proven actual deployments on the scale of millions of units
SSN, Coronis/France Telecom, Elster, CellNet/Hunt, GE, Eka
Disadvantages
Spectrally less efficient than other techniques
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<author>, <company>

8. Parameter Details Narrow band channels
July 2009
Parameter Details
Narrow band channels
Good channel diversity while also supportive of PAR rates
Ability to use maximum transmit power as may be allowed by regulations (for example under US FCC part , the criteria for 1W FHSS), and adjust transmit power to fit the local regulations
Robust performance in the presence of multiple interference sources
Various channel spacings may be useful, and can be accommodated via method described in
Support for efficient frequency hopping
Primarily band agnostic and seamless inter-band hopping
Support for channel “black-listing” and “white-listing”, whereby access to specific channels can be restricted or encouraged
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9. Parameter Details (Cont’d)
July 2009
Parameter Details (Cont’d)
Data “whitening” (scrambling)
Whitens payload data (PSDU/MPDU) to avoid long series of 1’s and 0’s.
8-bit scrambler (255 bit sequence), taps at bits [8,4,3,2]
Scrambler re-seeded periodically for added reliability
A nominal data rate of 100 kbps consistent with the PAR, others optional
TPC for adapting to regulator domain and to support adaptation to observed link conditions
Monotonic RSSI
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10. PHY Frame (PPDU) Support for 2047 octet payload (802.1 MTU)
July 2009
PHY Frame (PPDU)
Support for 2047 octet payload (802.1 MTU)
IEEE CRC-32 on PHY frame
Extension bit for “future proofing”
Flexible preamble, further investigation pending
Octets: tbd 2 1
variable 4
Bits: tbd 16 8 11 32
Preamble
SFD
Scrambler Seed R F U E X T
Length
(PSDU)
CRC-32
SHR
PHR
PHY Payload
FCS
Structure of PPDU
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11. PIB table July 2009 Attribute Ident-tifier Type Range Description
phyNBFHPreambleLength
Int
2 - aMaxNBPreambleLen
Number of octets of preamble;
Default = 7.
phyNBFHPreambleValue
Octet
0-0xff
Bit pattern for preamble.
Default = 0xAA (alternating 1/0s)
phyNBFHSFDValue
16Bits
0x0000-0xffff
NB PHY start of frame delimiter. Default value = 0xf3a0
phyNBFHTransmitPower
1 to phyNBFHNumPowerLevels
The desired power level
phyNBFHNumPowerLevels
1-255
The number of power levels supported. This is a read-only field, readable through a PLME-GET.request.
phyNBFHOutputPower
Array
phyNBFHNumPowerLevels of floating point numbers
For each power level, it stores the transmit power output value in units of dBm. This is a read-only field, readable through a PLME-GET.request.
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12. PIB Table (Cont’d) July 2009 Attribute Ident-tifier Type Range
Description
phyMaxChanSeqSize†
Int
85 channels if phyCurrentPage = 8 (902 MHz band NBFH) and 261 channels if phyCurrentPage = 9 (2.4 GHz NBFH)
phyCurrentChannel
< phyMaxChanSeqSize
The RF channel to use for all following
transmissions and receptions (see
6.1.2).
phyChannelsSupported†
Array
An R x 512 bit array, where R ranges from 1 to 32
Bitmap of supported channels.
phyCurrentPage
Page 8 for band 902 MHz NBFH, Page 9 for band 2.4 GHz NBFH
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13. July 2009
Data Transfer
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14. July 2009
Data whitening
Whitens payload data (PSDU/MPDU) to avoid long series of 1’s and 0’s.
8-bit scrambler (255 bit sequence)
taps at bits [8,4,3,2]
Ability to reset the scrambling seed across packets and retransmissions
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15. A PHY Parameter Set Parameters Value Notes
July 2009
A PHY Parameter Set
Parameters
Value
Notes
Minimum receiver sensitivity
-90 dBm
PER 10-2 for 1500 octet payload
Adjacent channel separation
300 KHz
Alternate channel separation
600 KHz
Adjacent channel rejection
10 dB
Measured at sensitivity + 3dB against a modulated signal with balanced 1’s and 0’s
Alternate channel rejection
30 dB
Nominal modulation index
0.5
Modulation index range
+ 20%
To support + 5KHz
Nominal data rate
100 kb/s
Frequency and time tolerance/stability
+ 10 ppm
Locked clocks
TX amplifier rise time
< 100 us
Channel switch time
< 500 us
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16. Free Running Clock (FRC)
July 2009
Free Running Clock (FRC)
It is required that a free running clock be available, accessible by both the PHY and MAC and used to time stamp packet receptions and schedule packet transmissions.
The PHY captures the time of PPDU arrival upon receipt. A snapshot of the FRC is taken at the receipt of the last bit of the scrambler seed. If available, the FRC value captured will be reported with the PSDU in the PD_DATA.indication.
The FRC may also be used by the MAC layer for scheduling packet transmissions to occur at a specific FRC value.
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17. General Radio Specification
July 2009
General Radio Specification
The TX-to-RX turnaround time refers to the shortest time possible at the air interface from the trailing edge of the last symbol of a transmitted PPDU to the leading edge of the first symbol of the next received PPDU.
The RX-to-TX turnaround time refers to the shortest time possible at the air interface from the trailing edge of the last symbol of the received PPDU to the leading edge of the first symbol of the next transmitted PPDU.
The RX-to-TX turnaround time shall be less than or equal to 1 ms and shall be greater than or equal to the TX-to-RX turnaround time.
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18. July 2009
MAC Support
MAC controls frequency hopping and programs PHY accordingly.
In the proposed design, nodes can communicate by knowing:
The receiver frequency hopping sequence and
Relative time at that receiver
MAC also responsible for enforcing regulatory requirements for channel occupancy
Reliability support
Packet acknowledgment
Packet retransmission
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19. Conclusions Proposal consistent with scope of approved SUN PAR
July 2009
Conclusions
Proposal consistent with scope of approved SUN PAR
Support millions of users at low data rates
Robust and available
Low cost and ubiquitous
Operation in unlicensed spectrum
Applications supported by this proposal are consistent with those proposed by utilities and manufacturers during PAR approval process and in tutorials
Some references:
wng0-the-smart-grid.ppt
utility-view-of-nan-drivers-and-requirements.pdf
nan-strawman-5c-input-for-wnan.doc
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