Draft ETSI TS 102 887-1
PHY Standard
Derived from IEEE 802.15.4g
Larry Taylor, Raporteur TS 102 887-1
20 March '12
SRD MG - London
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Summary
• IEEE 802.15 began work on amendment 4g (Smart
Utility Networks) in 2008, finishing its work at the end
of 2011
• ETSI ERM/TG28 began work on requirements for
Smart Metering (SMEP) in late 2009 and produced
– SMEP Systems Reference Document (SRDoc TR 102 886)
in late 2010
– M3N requirements were added in SRDoc TR 103 055 in
2011
– A draft PHY Technical Specification (TR 102 887-1) in late
2011
– All comments were resolved at ERM TG28 #31 Feb ‘12
• ETSI work on SMEP PHY was based on IEEE 802
15.4g
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ETSI TS 102 887-1
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ETSI TS 102 887-1 (1)
• 870-876/915-921MHz target spectrum
– Band under CEPT consideration for expansion of RFID & SRD use in
Europe
– Primary user (Mobile Service) in 873-876/918-921MHz
• Extension of GSM-R
– Some Military users in 870-872MHz and other sub-bands
– High power RFID (4x400kHz channels) proposed for 915-921MHz band
• Coexistence study (WI41) will determine operating parameters
– Maximum transmit power
– Duty Cycle limits
– Out of Band limits
• TS 102 887-1 designed with time constrained operation in mind
for E-GSM-R coexistence
– Coexistence tests at Kolberg test lab in 2009
•
•
•
•
20 March '12
FSK waveform envelope
200kHz channel spacing
20ms burst length
High power (>100mW)
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ETSI TS 102 887-1 (2)
Rationale & Goals
– Optimize co-existence with E-GSM-R & other
SRDs
– Satisfy Smart Metering requirements for RF
systems including RF MESH designs
– Support M3N requirements for low data rate &
battery operated devices
• High link margin for difficult propagation environment
• Good properties for battery powered devices
– Spectrum efficiency
• Minimize inter- & intra-system interference & maximize
capacity
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ETSI TS 102 887-1 (3)
• GFSK & O-QPSK PHY Summary
Data Parameters
PHY
GFSK
O-QPSK
Option
Modulation
Index
Symbol Rate
(ksymbol/s) †
Data Rate
(kbps)
Symbols
Note
1
0.5
100
{100, 50}*
Binary
See note 1
2
0.5
200
{200,
100}*
Binary
See note 1
3
1
50
{50,25}*
Binary
See note 2
4
0.5
150
{150, 75}*
Binary
See note 2
5
0.33
100
{200, 100}*
4-ary
See note 2
1
N/A
100
6.25
Binary
See note 1
2
N/A
200
12.5
Binary
See note 1
* For the GFSK PHY, pairs of rates {x, y} are shown. The first rate, x corresponds to the PSDU bit rate
when FEC is not enabled, and the second rate, y corresponds to the PSDU bit rate when FEC is enabled.
† For the O-QPSK PHY, the symbol rate is equal to the chip rate with unit “kchip/s”.
Note 1: GFSK and O-QPSK options 1 & 2, these PHYs are defined in a manner intended to facilitate detection and
interpretation of modulation and data rate from the received synchronization header (SHR) see Figure 1 and Figure 2..
Note 2: GFSK options 3-5 may also be implemented with mutual detection and interpretation of modulation and data
rate but with additional complexity.
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• OFDM PHY Summary
OFDM PHY Parameter (see note 1)
Option 3
(See note 3)
Option 4
(See Note 2)
Nominal bandwidth (kHz)
Channel spacing (kHz)
DFT size
Active tones
Number of pilot tones
Number of data tones
281
400
32
26
2
24
156
200
16
14
2
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Note 1: OFDM options are defined using similar occupied
bandwidth as the GFSK & O-QPSK PHYs to permit, as far as
possible, implementations which support multiple different PHYs.
Note 2: The Option 3 & Option 4 names are taken from [2].
Note 3: Option 3 may be subject to specific regulatory limits owing
to its occupied bandwidth.
OFDM Modulation & Coding Scheme
MCS1
(QPSK rate ½ and 2 frequency repetition)
MCS2
(QPSK rate ½ and 2 frequency repetition)
MCS3 (QPSK rate ½)
MCS4 (QPSK rate ¾)
MCS5 (kb/s) (16 QAM rate ½)
MCS6 (kb/s) (16QAM rate ¾)
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Option 3
(kbps)
Option 4
(kbps)
50
N/A
100
50
200
300
400
600
100
150
20
300
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ETSI TS 102 887-1 (4)
• GFSK PHY
–
–
–
–
Derived from 802.15.4g MR-FSK
Mandatory PHY
200kHz channel raster aligned with E-GSM-R
SFD signals FEC coding
• Simplified PHY Header compatible with IEEE
802.15.4g
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ETSI TS 102 887-1 (5)
• O-QPSK PHY
–
–
–
–
–
–
–
Derived from 802.15.4g MR-OQPSK PHY
Optional low data rate PHY
200 kHz channel raster
Modulation: GMSK with BT = 0.5
6.25 kbps (chip rate is 100 kchip/s)
12.5 kbps (chip rate is 200 kchip/s)
chip pre-coding to obtain an O-QPSK type signal based on GMSK
modulation
– Additional fixed format PHY PDU for LDR E-GSM-R coexistence
• SFD signals PHY PDU type
– Variable length PDU with PHY Header
– Fixed format with 7 or 18 octet PSDU
– Protected by header checksum
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SRD MG - London
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ETSI TS 102 887-1 (5)
• OFDM PHY
– Option 1
• Equivalent to IEEE 802.15.4g OFDM Option 4
• 200kHz spacing
• 50-300kbps
– Option 2
•
•
•
•
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Equivalent to IEEE 802.15.4g OFDM Option 3
400kHz spacing
50-600kbps
Owing to larger occupied bandwidth may required
special regulatory consideration
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Meeting European Requirements
• From SRDoc 102 886
– 100kbps 100k symbols/sec data rate
– 50kbps via FEC
• Better performance for poor links than uncoded 50kbps
– Higher rates via increased symbol rate
• 200kbps 200k symbols/sec
• From SRDoc 103 055
– Low Data Rate (LDR) for battery operated devices
•
•
•
•
6.25kbps 100kcps
12.5kbps 200kcps
Battery operated devices
Harsh propagation environments
– Fixed format PHY PDUs
• Fits 20ms E-GSM-R time-constrained coexistence mechanism
• Allows preamble sampling in other bands via concatenated PHY PDUs
• OFDM & Additional GFSK Modes for IEEE 802.15.4g
compatibility
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Summary
• Optimum coexistence with E-GSM-R
– Data rates fit in 200kHz E-GSM-R channel raster
– Low Data Rate for poor link conditions
• Compatible with time constrained sharing strategy
– Optimum number of channels in 870-876 MHz
• Minimizes intra- & inter-system interference
• Maximizes system capacity & spectrum efficiency
– Simplified implementation complexity
• Reduced 15.4g options where no specific advantage
– IEEE 802.15.4g compatibility
• GFSK PHY Modes – 200kHz & 400kHz bandwidths
• Low Rate O-QPSK
• OFDM PHY Modes 3&4
– Mode 3 may require special consideration owing to wide
occupied bandwidth
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