Chirp Spread Spectrum (CSS) PHY Submission

1
Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
DBO-CSS PHY Presentation for 802.15.4a Date
Submitted March 07, 2005 Source (1) John
Lampe, et al, (2) Kyung-Kuk Lee, et al Company
(1) Nanotron Technologies, (2) Orthotron Co.,
Ltd. Address (1) Alt-Moabit 61, 10555 Berlin,
Germany, (2) 709 Kranz Techono, 5442-1
Sangdaewon-dong, Jungwon-gu, Sungnam-si,
Kyungki-do, Korea 462-120 Voice (1) 49 30
399 954 135, (2) 82-31-777-8198 , E-Mail (1)
j.lampe_at_nanotron.com, (2) kyunglee_at_orthotron.com
Re This is in response to the TG4a Call for
Proposals, 04/0380r2 Abstract The Nanotron -
Orthotron DBO-CSS is described and the detailed
response to the Selection Criteria document is
provided Purpose Submitted as the candidate
proposal for TG4a Alt-PHY Notice This document
has been prepared to assist the IEEE P802.15. 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 P802.15.
2
Differentially Bi-OrthogonalChirp-Spread-Spectrum
PHY Proposal for 802.15.4a
by John Lampe, Rainer Hach, and Lars Menzer
Nanotron Technologies GmbH, Germany j.lampe_at_nanot
ron.com Kyung-Kuk Lee / Jong-Wha Chong Orthotron
Co., Ltd. / Hanyang Univ., Korea
kyunglee_at_orthotron.com
3
Contents

• DBO-CSS System Overview
• Selection Criteria Document Topics
• PAR and 5C Requirement Checklist
• Summary

4
DBO-CSS System Overview

• Chirp Property
• Concept of Sub-Chirps
• Block-diagram

? DBO-CSK Differentially Bi-Orthogonal
Chirp-Spread-Spectrum
5
DBO-CSS System Overview
Chirp Properties
Linear Chirp Rectangular Window
t
Linear Chirp Raised-Cosine Window
6
DBO-CSS System Overview
Concept of Sub-Chirps
Spectrum
0
Fbw 7.0 MHz rolloff 0.25 Fdiff 6.3 MHz Tc
4.8usec
-10
-20
-30
-40
-50
-20 -10 fc
10 20 (MHz)
Same Spectrum with IEEE802.11a / 11b
7
DBO-CSS System Overview
Concept of Sub-Chirps
Waveform
8
DBO-CSS System Overview
Block-diagram DBO-CSS Transmitter
Digital MOD
Low-Pass Filter
I/Q Modulator
LP
I
fT f 10 MHz
LP
Q
LO
fc
9
DBO-CSS System Overview
Block-diagram DBO-CSS Receiver
2
3
Low-Pass Filter
I/Q Demodulator
DDDL
Up
1
LP
ADC
I
Down
Digital DEMOD
LP
ADC
Q
LO
fR fLO 10 MHz
RSSI
DBO-CSS pulse
1
fc
Correlation pulse
2
Trigger signal with adaptive threshold
3
10
DBO-CSS System Overview
Block-diagram 8-ary DBO-CSS Modulator
11
Selection Criteria Document Topic

• Band in Use
• Signal Robustness
• interference mitigation techniques.
• Interference Susceptibility
• Coexistence
• Technical Feasibility
• Manufacturability
• Time to Market
• Regulatory Impact
• Backward Compatibility
• Scalability
• Mobility
• MAC Protocol Supplement
• PHY Layer Criteria
• Unit Manufacturing Cost/Complexity (UMC)
• Size and Form Factor
• Payload Bit Rate and Data Throughput

• Simultaneously Operating
• Piconets
• Signal Acquisition
• Clear Channel Assessment
• System Performance
• Error rate
• Receiver sensitivity
• Ranging
• Link Budget
• Power Management Modes
• Power Consumption
• Antenna Practicality

12
Selection Criteria Document Topic
Band in Use

• 2.4GHz ISM Band with 802.11b channel scheme
• 20MHz Bandwidth Consists of 4 sub-chirp
  signals per Carrier

13
Selection Criteria Document Topic
Signal Robustness

• Co-existence / Interference Mitigation
  Technique
• - Orthogonal / Quasi-Orthogonal Signal Set
• - High Spectral Processing Gain Chirp
• - Near-Far Problem FDM Channels (7ch
  _at_2.4GHz)
• Interference Susceptibility
• - Low Cross-Correlation property with
  Existing Signal
• Robustness
• - Heavy Multi-path Environment
• - SOP
• Low Sensitivity for Component Tolerance
• - Crystal 40ppm
• Mobility
• - Wide-band Chirp Insensitive for Fading
  Doppler Shift
• - Easily Maintaining Timing Sync. of
  Received Signal

14
Selection Criteria Document Topic
Signal Robustness Interference Mitigation
Techniques

• The proposed DBO-CSS PHY is designed to operate
  in a hostile environment
• Multipath
• Narrow and broadband intentional and
  unintentional interferers
• Since a chirp transverses a relatively wide
  bandwidth it has an inherent immunity to narrow
  band interferers
• Multipath is mitigated with the natural frequency
  diversity of the waveform
• Broadband interferer effects are reduced by the
  receivers correlator
• Forward Error Correction (FEC) can further reduce
  interference and multipath effects.
• Three non-overlapping frequency channels in the
  2.4 GHz ISM band
• This channelization allows this proposal to
  coexist with other wireless systems such as
  802.11 b, g and even Bluetooth (v1.2 has adaptive
  hopping) via DFS
• DBO-CSS proposal utilizes CCA mechanisms of
  Energy Detection (ED) and Carrier Detection
• These CCA mechanisms are similar to those used in
  IEEE 802.15.4-2003
• In addition to the low duty cycle for the
  applications served by this standard sufficient
  arguments were made to convince the IEEE 802
  sponsor ballot community that coexistence was not
  an issue.

15
Selection Criteria Document Topic
Signal Robustness Interference Susceptibility
Support for Interference Ingress

• Example (without FEC)
• Bandwidth B of the chirp 20 MHz
• Duration time T of the chirp 4.8 µs
• Center frequency of the chirp (ISM band) 2.437
  GHz
• Processing gain, BT product of the chirp 19.8
  dB
• Eb/N0 at detector input (BER10E-4) 12.5 dB
• In-band carrier to interferer ratio (C/I _at_
  BER10-4) 12.5 19.8 -7.3 dB

16
Selection Criteria Document Topic
Signal Robustness Coexistence

• Low interference egress
• IEEE 802.11b receiver
• More than 30 dB of protection in an adjacent
  channel
• Almost 60 dB in the alternate channel
• These numbers are similar for the 802.11g
  receiver

17
Selection Criteria Document Topic
Technical Feasibility Manufacturability
18
Selection Criteria Document Topic
Technical Feasibility Time to Market

• No regulatory hurdles
• DBO-CSS based chips are available on the market
• No research barriers no unknown blocks
• Normal design and product cycles will apply
• Can be manufactured in all CMOS

19
Selection Criteria Document Topic
Technical Feasibility Regulatory Impact

• Devices manufactured in compliance with the
  DBO-CSS proposal can be operated under existing
  regulations in all significant regions of the
  world
• - Including but not limited to North and South
  America, Europe, Japan, China, Korea, and most
  other areas
• - There are no known limitation to this proposal
  as to indoors or outdoors
• The DBO-CSS proposal would adhere to the
  following worldwide regulations
• - United States Part 15.247 or 15.249
• - Canada DOC RSS-210
• - Europe ETS 300-328
• - Japan ARIB STD T-66

20
Selection Criteria Document Topic
Technical Feasibility Backward Compatibility

• Due to the similarities with DSSS it is possible
  to implement this proposal in a manner that will
  allow backward-compatibility with the 802.15.4
  2.4 GHz standard.
• The transmitter changes are relatively
  straightforward.
• Changes to the receiver would include either dual
  correlators or a superset of DBO-CSS and DSSS
  correlators.
• Optional methods for backward-compatibility could
  be left up to the implementer
• - mode switching
• - dynamic change (on-the-fly) technique
• This backward-compatibility would be a
  significant advantage in the marketplace by
  allowing these devices to communicate with
  existing deployed 802.15.4 infrastructure and
  eliminating customer confusion.

21
Selection Criteria Document Topic
Scalability Data-rate

• Mandatory rate 1 Mb/s
• Optional rates 500 Kb/s, 250 Kb/s
• Lower data rates achieved by using interleaved
  FEC
• Lower chirp rates would yield better performance
• - longer range, less retries, etc. in an AWGN
  environment or a multipath limited environment
• It should be noted that these data rates are only
  discussed here to show scalability, if these
  rates are to be included in the draft standard
  the group must revisit the PHY header such as the
  SFD.

22
Selection Criteria Document Topic
Scalability Frequency Bands

• The proposer is confident that the DBO-CSS
  proposal would also work well in other frequency
  bands
• Ex) Including the 5 GHz UNII / ISM bands

23
Selection Criteria Document Topic
Scalability Power Levels

• For extremely long ranges the transmit power may
  be raised to each countrys regulatory limit, for
  example
• The US would allow 30 dBm of output power with up
  to a 6 dB gain antenna
• The European ETS limits would specify 20 dBm of
  output power with a 0 dB gain antenna
• Note that even though higher transmit power
  requires significantly higher current it doesnt
  significantly degrade battery life since the
  transmitter has a much lower duty cycle than the
  receiver, typically 10 or less of the receive
  duty cycle.

24
Selection Criteria Document Topic
Mobility

• Communication
• No system inherent restrictions are seen for this
  proposal
• The processing gain of chirp signals is extremely
  robust against frequency offsets such as those
  caused by the Doppler effect when there is a high
  relative speed vrel between two devices.
• The Doppler effect must also be considered when
  one device is mounted on a rotating machine,
  wheel, etc.
• The limits will be determined by other, general
  (implementation-dependent) processing modules
  (AGC, symbol synchronization, etc.).
• Ranging
• The ranging scheme proposed in this document
  relies on the exchange of two hardware
  acknowledged data packets
• One for each direction between two nodes
• The total time for single-shot (2 data, 2 Ack)
  ranging procedure between the two nodes is the
  time tranging which, depending on the
  implementation, might be impacted by the uC
  performance. During this time the change of
  distance should stay below the accuracy da
  required by the application. The worst case is

• For da 1m
• tranging 2 ms this yields
• vrel ltlt 1000 m/s

25
Selection Criteria Document Topic
MAC Protocol Supplement

• There are very minimal anticipated changes to the
  15.4 MAC to support the proposed Alt-PHY.
• Three channels are called for with this proposal
  and it is recommended that the mechanism of
  channel bands from the proposed methods of TG4b
  be used to support the new channels.
• There will be an addition to the PHY-SAP
  primitive to include the choice of data rate to
  be used for the next packet. This is a new field.
• Ranging calls for new PHY-PIB primitives are
  expected to be developed by the Ranging
  subcommittee.

26
Selection Criteria Document Topic
PHY Layer Criteria Manufacturing Cost/Complexity
BaseBand Digital BaseBand Digital Estimated Complexity 500Kbps / 250Kbps gates Estimated Complexity 500Kbps / 250Kbps gates Data-Rate Data-Rate
BaseBand Digital BaseBand Digital Estimated Complexity 500Kbps / 250Kbps gates Estimated Complexity 500Kbps / 250Kbps gates 250 Kbps 1MHz / 500 Kbps
Tx Scrambler 154 1.5K / 1.6K O O
Tx FEC Encoder (r1/2) 100 1.5K / 1.6K O X
Tx Symbol Mapper 13 1.5K / 1.6K O O
Tx Differential Encoder 56 1.5K / 1.6K O O
Tx Chirp-pulse Modulator 290 1.5K / 1.6K O O
Tx Framer Others 1K 1.5K / 1.6K O O
Rx Differential Detector 39k 49.4K / 145K O O
Rx Symbol Demapper 200 49.4K / 145K O O
Rx Max Selector 100 49.4K / 145K O O
Rx FEC Decoder (r1/2) 95K 49.4K / 145K O X
Rx Descrambler 154 49.4K / 145K O O
Rx Deframer Others 10K 49.4K / 145K O O
Common Common 5K 5K O O
Transceiver Transceiver Transceiver Transceiver 152K 56K
27
Selection Criteria Document Topic
PHY Layer Criteria Manufacturing Cost/Complexity

• Target processRF-CMOS, 0.18 µm feature size

Pos. Block description Estimated Area Unit
1 Receiver with high-end LNA 2.00 mm²
2 Transmitter, Pout 10 dBm 1.85 mm²
3 Digitally Controlled Oscillator miscellaneous blocks 0.62 mm²
4 Digital and MAC support 0.30 mm²
5 Digital Dispersive Delay Line (DDDL) for the proposed chirp duration 0.32 mm²
6 Chirp generator for the proposed chirp duration 0.08 mm²
Occupied chip area for all major blocks required to build complete transceiver chip utilizing DBO-CSS technology 5.17 mm²
28
Selection Criteria Document Topic
PHY Layer Criteria Manufacturing Cost/Complexity

• Target processRF-CMOS, 0.13 µm feature size

Pos. Block description Estimated Area Unit
1 Receiver with high-end LNA 1.90 mm²
2 Transmitter, Pout 10 dBm 1.71 mm²
3 Digitally Controlled Oscillator miscellaneous blocks 0.59 mm²
4 Digital and MAC support 0.19 mm²
5 Digital Dispersive Delay Line (DDDL) for the proposed chirp duration 0.21 mm²
6 Chirp generator for the proposed chirp duration 0.06 mm²
Occupied chip area for all major blocks required to build complete transceiver chip utilizing DBO-CSS technology 4.66 mm²
29
Selection Criteria Document Topic
PHY Layer Criteria Size and Form Factor

• The implementation of the DBO-CSS proposal will
  be much less than SD Memory at the onset
• Following the form factors of Bluetooth and IEEE
  802.15.4 / ZigBee
• The implementation of this device into a single
  chip is relatively straightforward
• As evidenced in the Unit Manufacturing
  Complexity slides

30
Selection Criteria Document Topic
PHY Layer Criteria Size and Form Factor
SD Memory (32mm X 24 mm)
SD Memory (32mm X 24 mm)
2.4 GHz

• Ex)
• Battery Capacity 3V x 30mAh (324Joule)
• Dimension 10 x 2.5 (Dia. x Ht. mm)

31
Selection Criteria Document Topic
PHY Layer Criteria Bit Rate and Data Throughput

• Payload Bit-rate
• Data-rate 1MHz / 500Kbps / 250Kbps per
  piconet
• Aggregated Data-rate Max. 4Mbps (4 X 1Mbps)
  per FDM Channel
• FDM Channels 7 CH. (2.4GHz)
• Data Throughput
• Payload bit-rate 1Mbps / 500Kbps / 250Kbps
• Throughput 446 Kbps / 293 Kbps / 173.7 Kbps

Payload 32byte
5byte
DATA Frame
ACK Frame
DATA Frame
TACK
TLIFT
114 / 156 / 240 µsec
330 / 588 / 1104 µsec
574 / 874 / 1474 µsec
TACK TLIFT 130usec
32
Selection Criteria Document Topic
PHY Layer Criteria Bit Rate and Data Throughput
Data Frame Payload bit-rate 1Mbps (r1) /
500Kbps (r1) / 250Kbps (r1/2)
5Chirp 1Chirp 6Chirp
43chirps (1Mbps) / 86chirps (500Kbps) or
172chirps (250Kbps)
Preamble
Delimiter
Length Rate
MPDU
(8 1)bit
(32X8 2) bit
330 µsec (1Mbps) / 588 µsec (500Kbps) / 1104
µsec (250Kbps)
ACK Frame Payload bit-rate 1Mbps(r1) /
500Kbps (r1) / 250Kbps (r1/2)
5Chirp 1Chirp 6Chirp
7chirps (1Mbps) / 14chirps (500Kbps) / 28chirps
(250Kbps)
Preamble
Delimiter
Length Rate
MPDU
(8 1)bit (5X8 2) bit
114 µsec (1Mbps) / 156 µsec (500Kbps) / 240 µsec
(250Kbps)
33
Selection Criteria Document Topic
PHY Layer Criteria Bit Rate and Data Throughput
Octets 4 1 or 2 1 Variable (up to 256)
Preamble SFD Frame length (8 bits) PHY payload
SHR SHR PHR PSDU

• The SFD structure has different values for, and
  determines, the effective data rate for PHR and
  PSDU
• The Preamble is 32 bits in duration (a bit time
  is 1 µs)
• In this proposal, the PHR field is used to
  describe the length of the PSDU that may be up to
  256 octets in length
• In addition to the structure of each frame, the
  following shows the structure and values for
  frames including overhead not in the information
  carrying frame

34
Selection Criteria Document Topic
PHY Layer Criteria Bit Rate and Data Throughput
35
Selection Criteria Document Topic
Simultaneously Operating Piconets

• Separating Piconets by frequency division
• This DBO-CSS proposal includes a mechanism for
  FDMA by including the three frequency bands used
  by 802.11 b, g and also 802.15.3
• It is believed that the use of these bands will
  provide sufficient orthogonality
• The proposed chirp signal has a rolloff factor of
  0.25 which in conjunction with the space between
  the adjacent frequency bands allows filtering out
  of band emissions easily and inexpensively.

36
Selection Criteria Document Topic
Simultaneously Operating Piconets
Correlation Power (For Preamble Detection)
t
CSK Signal Quasi-Orthogonal Property
Correlation Property between the piconet Does not
need Synchronization inter-piconet
Each of CSK Signal consists of 4 sub-chirp
signals.
37
Selection Criteria Document Topic
Simultaneously Operating Piconets
Complex Amplitude (for Data Demod)
I II III IV
CSK Signal Quasi-Orthogonal Property
Correlation Property between piconet
Each of CSK Signal consists of 4 sub-chirp
signals.
38
Selection Criteria Document Topic
Simultaneously Operating Piconets

• SOP Assigning Different Time-Gap between the
  Chirp-Shift-Keying Signal
• Minimize ISI for CM8 NLOS Assign the Time-Gap
  between symbol more then 200nsec

39
Selection Criteria Document Topic
Simultaneously Operating Piconets
Interference Tested by Packet (32 bytes Random
Data)
I II III IV
Differential Detection Property between piconet
Each of CSK Signal consists of 4 sub-chirp
signals.
40
Selection Criteria Document Topic
Simultaneously Operating Piconets

• Available SOPs
• 2.4GHz 4piconets/FDM Ch. x 7FDM Ch. 28
  SOPs
• 5.2GHz 4piconets/FDM Ch. x 8FDM Ch. 32
  SOPs
• 5.7GHz 4piconets/FDM Ch. x 6FDM Ch. 24
  SOPs

41
Selection Criteria Document Topic
Signal Acquisition Block-diagram
Differential Detector (T1)
Select Largest
A/D
Symbol De-Mapper
Data
Differential Detector (T2)
42
Selection Criteria Document Topic
Signal Acquisition Miss Detection Probability
n2
Preamble Detection
43
Selection Criteria Document Topic
Signal Acquisition

• Although DBO-CSS could use a shorter preamble,
  for consistency with IEEE 802.15.4-2003 this
  DBO-CSS proposal is based upon a preamble of 32
  symbols which at 1MS/s is 32 µs
• Existing implementations demonstrate that
  modules, which might be required to be adjusted
  for reception (gain control, frequency control,
  peak value estimation, etc.), can settle in this
  time

44
Selection Criteria Document Topic
Clear Channel Assessment
45
Selection Criteria Document Topic
System Performance

• Since this proposal refers to the 2.4GHz ISM
  band, only channel models with complete parameter
  sets covering this frequency range can be
  considered
• These are LOS Residential (CM1) and NLOS
  Residential (CM2).
• The SCD requirements on the payload size to be
  simulated seem to be somewhat inconsistent. At
  some point 10 packets with 32 bytes are mentioned
  which would be a total of 2560 bits. On the other
  hand a PER of 1 is required which mean
  simulating much more than 100 packets or 25600
  bits.
• Accurate results are obtained when large number
  of independent transmissions of symbols are
  simulated.
• BER is , with N
  number bits.
• For example, with PER1 and N256 (32 octets) we
  get BER3.9258E-5

46
Selection Criteria Document Topic
Channel Model LOS Residential (CM1)
47
Selection Criteria Document Topic
Channel Model NLOS Residential (CM2)
48
Selection Criteria Document Topic
System Performance BER (CM2)
49
Selection Criteria Document Topic
System Performance PER (CM2)

• Transmit power of 10 dBm
• 1 MBit / sec
• No FEC

50
Selection Criteria Document Topic
System Performance

• Simulation over 100 channel impulse responses (as
  required in the SCD) were performed for channel
  model 1 and channel model 2.
• No bit errors could be observed on channel model
  1 (simulated range was 10 to 2000m). This is not
  really surprising because this model has a very
  moderate increase of attenuation over range
  (n1.79)
• The results for channel model 2 are presented.
  The parameter n4.48 indicates a very high
  attenuation for higher ranges. The results were
  interpreted as PER respectively and for
  convenience were plotted twice (linear and log y
  scale).

51
Selection Criteria Document Topic
System Performance

• This figure shows the analytical BER values for
  2-ary orthogonal coherent and non coherent
  detection and the corresponding simulation
  results (1E7 symbols) for up down chirp (using
  the chirp signals defined above)
• The performance loss due to the non-orthogonality
  of up and down chirps is very small.

52
Selection Criteria Document Topic
System Performance
AWGN (Data Rate 1Mbps (QPSK) / 500kbps (BPSK)
n2
Distance (meter)
53
Selection Criteria Document Topic
System Performance
CM2 (Data Rate 1Mbps (QPSK) / 500kbps (BPSK)
n2
54
Selection Criteria Document Topic
Ranging
TOA Estimation

• Coarse Differential demodulation peak
• Fine Correlation peak
• Precise Receive signal post-processing
  (Spectrum estimation or curve fitting)
• Simulation Results

TOA Processing

• SDS TWR Technique
• Error Sensitivity Analysis
• Simulation Results

55
Selection Criteria Document Topic
Ranging TOA Estimation for Ranging
Noise and Jitter of Band-Limited Pulse Given a
band-limited pulse with noise su we want to
estimate how the jitter (timing error) st, is
affected by the bandwidth B. Jitter can be
represented as a variation in the rising edge of
a pulse through a given threshold,
56
Selection Criteria Document Topic
Ranging TOA Estimation for Ranging

• The SN at the matched filter output is 2Es/N0
• If we assume a pulse with a rise time trise which
  is the inverse of the pulse bandwidth B (trise
  1/B) we can derive
• Bandwidth and signal to noise ratio can be traded
  against each other.

57
Selection Criteria Document Topic
Ranging TOA Estimation Using Chirp Signals

• Coarse Timing Detection
• - Peak of Differential Detection (Averaging
  over 4 or more Symbols)
• Fine Timing Detection
• - Cross-Correlation of Sampled Input Signal
• - Fine Timing by Interpolation (Fraction of
  Sampling-Clock Resolution lt 1nsec)
• - Averaging over 4 or more Symbols
• - Less than 1m Ranging Resolution _at_ Eb/No gt
  24dB

58
Selection Criteria Document Topic
Ranging TOA Estimation Using Chirp Signals

• One special property of chirp signals is that
• Time shifts can be transformed into
• frequency shifts
• thus
• TOA estimation can be transformed to spectral
  estimation
• which has the advantage that
• Wide bandwidth and high sampling frequency are
  not required

59
Selection Criteria Document Topic
Ranging TOA Estimation Using Chirp Signals
A
Assume a linear chirp signal
t
and a time-shifted copy of this signal
f
t
A
t
By multiplying the two, a constant frequency
signal is generated!
f
t
60
Selection Criteria Document Topic
Ranging TOA Estimation Using Chirp Signals
h
Given a channel impulse response (CIR),
t
A
t
transmitting a chirp signal over it,
f
t
and multiplying with a chirp signal of equal
characteristic
A
t
will result in a signal with frequency
components corresponding to the pulses of the CIR.
f
power
t
frequency
61
Selection Criteria Document Topic
Ranging TOA Estimation Using Chirp Signals

• From the estimated frequency components, the time
  positions of the multipath components can be
  calculated
• and thus
• the time of the first arrival can be found!

62
Selection Criteria Document Topic
Ranging TOA Estimation Using Chirp Signals
63
Selection Criteria Document Topic
Ranging TOA Estimation Using Chirp Signals

• Estimation Precision lt 1m _at_ Eb/No greater
  than 24dB

Timing-error Variance (Chirp BW 20MHz)
AWGN
64
Selection Criteria Document Topic
Ranging Symmetrical Double-Sided Two-Way
Ranging (SDS TWR)
Double-Sided Each node executes a round trip
measurement. Symmetrical Reply Times of both
nodes are identical (TreplyA TreplyB). Results
of both round trip measurements are used to
calculate the distance.
Tround ... round trip time Treply ... reply
time Tprop ... propagation of pulse
65
Selection Criteria Document Topic
Ranging Effect of Time Base Offset Errors
Assuming offset errors eA, eB of the timebases of
node A and B we get
On the condition that the two nodes have almost
equal behavior, we can assume
This has the effect that timebase offsets are
canceled out
Calculations show that for 40 ppm crystals and 20
µs max difference between TroundA and TroundB
and between TreplyA and TreplyB an accuracy
below 1 ns can easily be reached!
total error due to clock
66
Selection Criteria Document Topic
Ranging Influence of Symmetry Error
Example system EtA 40 ppm, EtB 40 ppm
(worst case combination)
d ?d (?Treply 20 ns) ?d (?Treply 200 ns) ?d (?Treply 2 µs) ?d (?Treply 20 µs)
10 cm 0.012 cm 0.12 cm 1.2 cm 12 cm
1 m 0.012 cm 0.12 cm 1.2 cm 12 cm
10 m 0.05 cm 0.12 cm 1.2 cm 12 cm
100 m 0.4 cm 0.4 cm 1.2 cm 12 cm
1 km 4 cm 4 cm 4 cm 12 cm
10 km 40 cm 40 cm 40 cm 40 cm

• A ?Treply of between 2 µs and 20 µs is typical
  for a low-cost implementation.
• Implementations with symmetry error below 2 µs
  are feasible.
• Conclusion Even a 20 µs symmetry error allows
  excellent single-pulse accuracy of distance.

67
Selection Criteria Document Topic
Ranging Simulation of a SDS TWR System
Example system Simulates SDS TWR
Dithering Averaging Crystal Errors 40
ppm Single shot measurements _at_ 1 MBit/s data rate
(DATA-ACK) Transmit Jitter 4 ns
(systematic/pseudo RN-Sequence) Pulse detection
resolution 4 ns Pulses averaged per packet
32 Symmetry error 4 µs (average) Distance 100
m Results of Distance Error ?d ?dWC lt 50
cm ?dRMS lt 20 cm
68
Selection Criteria Document Topic
Link Budget
Parameter mandatory option 1 option 2 option 3
peak payload bit rate(Rb) 1000 500 250 250 kbps
Average Tx Power(Pt) 10 10 10 1000 mW
Average Tx Power(Pt) 10 10 10 30 dBm
Tx antenna gain(Gt) 0 0 0 0 dBi
fc' sqrt(fminfmax) -10dB 2.44 2.44 2.44 2.44 GHz
Path loss at 1meter(L120log10(4pifc'/c)) 40.2 40.2 40.2 40.2 dB
distance 30 30 100 1000 m
path loss at d m(L220log10(d)) 29.5 29.5 40 60 dB
Rx antenna gain(Gr) 0 0 0 0 dBi
Rx power(Pr PtGtGr-L1-L2(dB)) -59.7 -59.7 -70.2 -70.2 dBm
Average noise power per bit -114.0 -117.0 -120.0 -120.0 dBm
Rx Noise Figure(Nf) 7 7 7 7 dB
Average noise power per bit(PnNNf) -107.0 -110.0 -113.0 -113.0 dBm
Minimum Eb/No(S) 12.5 12.5 12.5 12.5 dB
Implementation Loss(I) 3 3 3 3 dB
Link Margin (MPr-Pn-S-I) _at_ distance d 31.8 34.8 27.3 27.3 dB
Proposed Min. Rx Sensitivity Level -91.5 -94.5 -97.5 -97.5 dBm
69
Selection Criteria Document Topic
Sensitivity

• The sensitivity to which this DBO-CSS proposal
  refers is based upon non-coherent detection
• It is understood that coherent detection will
  allow 2 - 3 dB better sensitivity but at the cost
  of higher complexity (higher cost?) and poorer
  performance in some multipath limited
  environments
• The sensitivity for the 1 Mb/s mandatory data
  rate is -91.5 dBm for a 1 PER in an AWGN
  environment with a front end NF of 7 dB
• The sensitivity for the optional 250 kb/s data
  rate is -97.5 dBm for a 1 PER in an AWGN
  environment with a front end NF of 7 dB

70
Selection Criteria Document Topic
Power Management Modes

• Power management aspects of this proposal are
  consistent with the modes identified in the IEEE
  802.15.4 2003 standard
• There are no modes lacking nor added
• Once again, attention is called to the 1 Mbit/s
  basic rate of this proposal and resulting shorter
  on times for operation

71
Selection Criteria Document Topic
Power Consumption

• The typical DSSS receivers, used by 802.15.4, are
  very similar to the envisioned DBO-CSS receiver
• The two major differences are the modulator and
  demodulator
• The power consumption for a 10 dBm transmitter
  should be 198 mW or less
• The receiver for the DBO-CSS is remarkably
  similar to that of the DSSS with the major
  difference being the correlator
• The difference in power consumptions between
  these correlators is negligible so the power
  consumption for a 6 dB NF receiver should be 40
  mW or less
• Power save mode is used most of the time for this
  device and has the lowest power consumption
• Typical power consumptions for 802.15.4 devices
  are 3 µW or less
• Energy per bit is the power consumption divided
  by the bit rate
• The energy per bit for the 10 dBm transmitter is
  less than 0.2 µJ
• The energy per bit for the receiver is 60 nJ
• As an example, the energy consumed during an
  exchange of a 32 octet PDU between two devices
  would be 70.6 µJ for the sender and 33.2 µJ for
  the receiver

72
Selection Criteria Document Topic
Power Consumption
1Mbps / 500Kbps (No FEC) 1Mbps / 500Kbps (No FEC) 1Mbps / 500Kbps (No FEC) 250Kbps (FEC r1/2) 250Kbps (FEC r1/2) 250Kbps (FEC r1/2)
Logic Die Area Power Logic Die Area Power
RF _at_ Tx Power 10mW Tx D/A - 1.7 mm2 130 mW - 1.7 mm2 130 mW
RF _at_ Tx Power 10mW Rx A/D - 1.6 mm2 25 mW - 1.6 mm2 25 mW
RF _at_ Tx Power 10mW Common - 0.3 mm2 10 mW - 0.3 mm2 10 mW
Baseband _at_ Sampling-rate 40MHz Tx 1.5K 0.04 mm2 0.48 mW 1.6K 0.06 mm2 0.52 mW
Baseband _at_ Sampling-rate 40MHz Rx 49.4K 0.63 mm2 0.71 mW 145K 1.5 mm2 2.08 mW
Baseband _at_ Sampling-rate 40MHz Common 5K 0.08 mm2 0.42 mW 5K 0.08 mm2 0.42 mW
Total Tx 56K 4.35 mm2 141 mW 152K 5.24 mm2 141 mW
Total Rx 56K 4.35 mm2 36.1 mW 152K 5.24 mm2 37.5 mW
Deep Sleep Deep Sleep 5 uW 5 uW
Target Library 0.18 um Technology

• Power Consumption for Average Throughput 1
  Kbps (w/o FEC)
• - PTX 141mW / 293 481 uW
• - PRX 36.1mW /293 123 uW
• Battery 324Joule for Button Cell (10mm D. X
  2.5mm H) / 12,000Joules for AA Alkaline Cell
• - (PTX 50 X PRX)/51 130uW -----
  (Assume TTX TRX 150 duty-cycle for sensor
  node)
• - Battery Life TB 324/130e-6/3600/24
  28.8 days Continuously (Button Cell)
• - Battery Life TB 12000/130e-6/3600/24/365
  2.93 years Continuously (AA Alkaline Cell)

73
Selection Criteria Document Topic
Antenna Practicality

• The antenna for this DBO-CSS proposal is a
  standard 2.4 GHz antenna such as widely used for
  802.11b,g devices and Bluetooth devices.
• These antennas are very well characterized,
  widely available, and extremely low cost.
• Additionally there are a multitude of antennas
  appropriate for widely different applications.
• The size for these antennae is consistent with
  the SCD requirement.

74
Selection Criteria Document Topic
Antenna Practicality

• Antenna Size
• - less than SD-Memory size 24mm X 14mm
  _at_2.4GHz
• 
  12mm X 9mm _at_5.2/5.7GHz
• Frequency / Impulse Response
• - Almost Flat Freq. Response Narrow-band
• Radiation Characteristics
• - Isotropic 0dBi

75
PAR and 5C Requirement Checklist
76
Requirements Checklist

• DBO-CSS Proposal Meets the PAR and 5C
• Precision ranging capability accurate to one
  meter
• or better
• Extended range over 802.15.4-2003
• Enhanced robustness over 802.15.4-2003
• Enhanced mobility over 802.15.4-2003
• International standard
• Ultra low complexity (comparable to the goals
  for
• 802.15.4-2003)
• Ultra low cost (comparable to the goals for
  802.15.4-2003)
• Ultra low power consumption (comparable to the
  goals
• for 802.15.4-2003)
• Support coexisting networks of sensors,
  controllers,
• logistic and peripheral devices in multiple
  compliant
• co-located systems.

77
Summary
78
Summary

• DBO-CSS is simple, elegant, efficient
• Combines DSSS and UWB strengths
• Precise location-awareness
• Robustness multipath, interferers, correlation,
  FEC, 3 channels, CCA
• Mobility enhanced
• Optional backward compatibility with
  802.15.4-2003
• Excellent throughput
• SOPs FD channels
• Signal Acquisition excellent
• Link Budget and Sensitivity excellent
• Very minimal MAC changes, CCA supported
• Power Management and Consumption - meets or
  exceeds requirements
• Antenna many good choices
• Can be implemented with todays technologies
• Low-complexity, low-cost
• Size and Form Factor meets or exceeds
  requirements
• Low power consumption
• Globally certifiable