Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks
(WPANs)
Submission Title: [Merged UWB proposal for IEEE 802.15.4a Alt-PHY]
Date Submitted: [14 Mar 2005]
Source: [(1) Andy Molisch, (2) Francois Chin]
Company: [(1) MERL, 201 Broadway, Boston, USA, (2) Institute for Infocomm Research, Singapore]
Voice: [(1) +1 617 621 7500, (2) +65-68745687]
E-Mail: [(1) molisch@merl.com (2) chinfrancois@i2r.a-star.edu.sg]
Re: [Response to the call for proposal of IEEE 802.15.4a, Doc Number: 15-04-0380-02-004a ]
Abstract: [Merged Proposal to IEEE 802.15.4a Task Group]
Purpose: [For presentation and consideration by the IEEE802.15.4a committee]
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.
Slide 1
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doc.: IEEE 802.15-05-0158-00-004a
Authors
Institute for Infocomm Research:
Francois Chin, Xiaoming Peng, Sam Kwok, Zhongding
Lei, Kannan, Yong-Huat Chew, Chin-Choy Chai, Rahim,
Manjeet, T.T. Tjhung, Hongyi Fu, Tung-Chong Wong
General Atomics:
Naiel Askar, Susan Lin
Thales & Cellonics:
Serge Hethuin, Isabelle Bucaille, Arnaud Tonnerre,
Fabrice Legrand, Joe Jurianto
KERI & SSU & KWU:
Kwan-Ho Kim, Sungsoo Choi, Youngjin Park, HuiMyoung Oh, Yoan Shin, Won cheol Lee, and Ho-In Jeon
Create-Net & China UWB Forum:
Zheng Zhou, Frank Zheng, Honggang Zhang, Xiaofei
Zhou, Iacopo Carreras, Sandro Pera, Imrich Chlamtac
Staccato Communications:
Roberto Aiello, Torbjorn Larsson
Wisair:
Gadi Shor, Sorin Goldenberg
Slide 2
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Authors
CWC:
AetherWire:
CEA-LETI:
Ian Oppermann, Alberto Rabbachin
Mark Jamtgaard, Patrick Houghton
Laurent Ouvry, Samuel Dubouloz, Sébastien de Rivaz,
Benoit Denis, Michael Pelissier, Manuel Pezzin et al.
STMicroelectronics:
Gian Mario Maggio, Chiara Cattaneo, Philippe Rouzet & al.
MERL:
Andreas F. Molisch, Philip Orlik, Zafer Sahinoglu
Harris:
Rick Roberts
Time Domain:
Vern Brethour, Adrian Jennings
French Telecom R&D:
Patricia Martigne, Benoit Miscopein, Jean Schwoerer
Slide 3
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doc.: IEEE 802.15-05-0158-00-004a
Proposal Main Features
1. Impulse-radio based (pulse-shape independent)
2. Support for different receiver architectures (coherent/noncoherent)
3. Flexible modulation format
4. Support for multiple rates
5. Enables accurate ranging/positioning
6. Support for multiple SOP
Slide 4
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Motivation:
• Supports homogenous and heterogeneous network architectures
• Different classes of nodes, with different reliability requirements
(and cost) must inter-work
Slide 5
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UWB Technology
• Impulse-Radio (IR) based:
– Very short pulses  Reduced ISI
– Robustness against fading
– Episodic transmission (for LDR) allowing
long sleep-mode periods and energy
saving
• Low-complexity implementation
Slide 6
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Modulation Features
•
Simple, scalable modulation format
•
Flexibility for system designer
•
Modulation compatible with multiple
coherent/non-coherent receiver schemes
Slide 7
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Types of Receivers Supported
• Coherent Detection: The phase of the
received carrier waveform is known, and
utilized for demodulation
• Differential Chip Detection: The carrier
phase of the previous signaling interval is
used as phase reference for demodulation
• Non-coherent Detection: The carrier
phase information (e.g.pulse polarity) is
unknown at the receiver
Slide 8
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Pros (+) and cons (-) of RX architectures:
Coherent
•
•
•
•
•
+ : Sensitivity
+ : Use of polarity to carry data
+ : Optimal processing gain achievable
- : Complexity of channel estimation and RAKE receiver
- : Longer acquisition time
Differential (or using Transmitted Reference)
• + : Gives a reference for faster channel estimation (coherent approach)
• + : No channel estimation (non-coherent approach)
• - : Asymptotic loss of 3dB for transmitted reference (not for DPSK)
Non-coherent
• + : Low complexity
• + : Acquisition speed
• - : Sensitivity, robustness to SOP and interferers
Slide 9
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Overview
• Basic waveform that simultaneously supports demodulation by
either coherent or non-coherent receiver
– Non-coherent receiver can use either 2-PPM or OOK demodulation
– Coherent receiver can also resolved phase of pulse and benefits
from additional coding gain
– Differential / Transmit reference (TR) receiver can get information
form phase difference between data pulse and reference pulse
• Main idea:
– Common preamble signaling for different classes of nodes / type of
receivers (coherent / differential / non-coherent)
Slide 10
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Example System Parameters
Chip rate
24 Mcps **
# Pulse / Chip Period
1
Pulse Rep. Freq.
24 MHz
# Chip / symbol (Code length)
32
Symbol Rate
24/32 MHz = 0.75 MSps
info. bit / sym (Mandatory Mode)
4 bit / symbol
Mandatory bit rate
4 bit/sym x 0.75 MSps = 3 Mbps
#Code Sequences/ piconet
16 (4 bit/symbol)
Orthogonal Sequence Keying
Modulation
{+1,-1, 0} ternary pulse train /
{+1,-1} bipolar
Total # simultaneous piconets
supported
6 per FDM band
Multple access for piconets
Fixed sequence & FDM band for each piconet
** To be determined
Slide 11
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Multiple access
Multiple access within piconet: TDMA+CSMA/CA
same as 15.4
Multiple access across piconets: CDM + FDM
Different Piconet uses different Base Sequence &
different 500 MHz band
Slide 12
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Realization #1
Slide 13
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System Description
• Each piconet uses one set of code sequences for
different classes of nodes / type of receivers (coherent /
differential / non-coherent receivers)
• 16 Orthogonal Sequences of code length 32 to
represent a 4-bit symbol
• PRF (chip rate): 24 MHz (TBD)
– Low enough to avoid significant interchip interference
(ICI) with all 802.15.4a multipath models
– High enough to ensure low pulse peak power
• FEC: optional (or low complexity type)
Slide 14
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Criteria of Code Sequence Design
1. The sequence Set should have orthogonal (or near orthogonal)
cross correlation properties to minimise symbol decision error for
all the below receivers
a. For coherent receiver
b. For differential chip receiver
c. For transmitted reference receiver
d. For non-coherent symbol detection receiver
e. Energy detection receiver
2. Each sequence should have good auto-correlation properties
Slide 15
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Base Sequence Set
Seq 1
0+--000+-0+++0+0-0000+00-0-+00--
Seq 2
0-0+--000+0+0+-0+0000+-00+00+---
Seq 3
0-+0++---0+000-00-0+0++0000-+-00
Seq 4
00+0+--0--000-+-++00++0-00+0000-
Seq 5
0+-+-00-00++0000+0--0-0+000--+0+
Seq 6
000-+-0000++0+0-00-000+0---++0+-
• 31-chip Ternary Sequence set are chosen
• Only one sequence and one fixed band (no hopping) will be used
by all devices in a piconet
• Logical channels for support of multiple piconets
•6 sequences = 6 logical channels (e.g. overlapping piconets) for
each FDM Band
• The same base sequence will be used to construct the symbol-tochip mapping table
Slide 16
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Symbol-to-Chip Mapping:
Gray coded 16-ary Ternary Orthogonal Keying
Symbol
Cyclic shift
to right by n
chips, n=
32-Chip value
To obtain 32-chip per symbol, cyclic shift the Base
Sequence first, then append a ‘0’-chip in front
0000
0
0+--000+-0+++0+0-0000+00-0-+00--
0001
2
0--+--000+-0+++0+0-0000+00-0-+00
0011
4
000--+--000+-0+++0+0-0000+00-0-+
0010
6
0-+00--+--000+-0+++0+0-0000+00-0
0110
8
0–0-+00--+--000+-0+++0+0-0000+00
0111
10
000–0-+00--+--000+-0+++0+0-0000+
0101
12
00+00–0-+00--+--000+-0+++0+0-000
0100
14
0000+00–0-+00--+--000+-0+++0+0–0
1100
15
00000+00–0-+00--+--000+-0+++0+0–
1101
17
00–0000+00–0-+00--+--000+-0+++0+
1111
19
00+0–0000+00–0-+00--+--000+-0+++
1110
21
0++0+0–0000+00–0-+00--+--000+-0+
1010
23
00+++0+0–0000+00–0-+00--+--000+-
1011
25
0+-0+++0+0–0000+00–0-+00--+--000
1001
27
000+-0+++0+0–0000+00–0-+00--+--0
1000
29
0-000+-0+++0+0–0000+00–0-+00--+Slide 17
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doc.: IEEE 802.15-05-0158-00-004a
Modulation & Coding (Mode 1)
Binary
data
From
PPDU
Bit-toSymbol
Symbolto-Chip
Symbol
Repetition
Pulse
Generator
{0,1,-1} Ternary
Sequence
Mode 1- common signaling for all receivers
(e.g. Beacon)
Bit to symbol mapping:
group every 4 bits into a symbol
Symbol-to-chip mapping:
Each 4-bit symbol is mapped to one of 16 32-chip sequence,
according to 16-ary Ternary Orthogonal Keying
Symbol Repetition:
for data rate and range scalability
Pulse Genarator:
• Transmit Ternary pulses at PRF = 24MHz (TBD)
Slide 18
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Modulation & Coding (Mode 2)
Binary
data
From
PPDU
Bit-toSymbol
Symbolto-Chip
Symbol
Repetition
{0,1,-1} Ternary
Sequence
TernaryBinary
Pulse
Generator
{1,-1} Binary
Sequence
Mode 2 – for enhanced performance when receiver types are
known (except for energy detector)
Bit to symbol mapping:
group every 4 bits into a symbol
Symbol-to-chip mapping:
Each 4-bit symbol is mapped to one of 16 32-chip sequence, according to 16-ary
Ternary Orthogonal Keying
Symbol Repetition:
for data rate and range scalability
Ternary to Binary conversion:
(-1/+1 → 1,0 → -1)
Pulse Genarator:
• Transmit bipolar pulses at PRF = 24MHz (TBD)
Slide 19
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Code Sequence
Properties & Performance
1.
2.
AWGN Performance
Multipath Performance (in Appendix)
I.
For Coherent Symbol Detector
II.
For Non-coherent Symbol Detector
III. For Differential Chip Detector
IV. For Energy Detector
Slide 20
Mar. 2005
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AWGN Performance
AWGN performance @ 1% PER
@ 3 Mbps
Coherent symbol
detection
Non-coherent
symbol detection
Differential chip
detection
Energy detection
Mode 1
6.5 dB
8.5 dB
13 dB
13.5 dB
Mode 2
6.5 dB
7.5 dB
11.5 dB
-
Slide 21
Mar. 2005
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Summary
The proposed system:
• Impulse-radio based system coupled
with a Common ternary signaling allows
operation among different classes of
nodes / type of receivers, with varying
cost / power / performance trade-off
• Is robust against multipath and SOP
interference
Slide 22
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Realization #2
Slide 23
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Non-Coherent and Coherent Demodulation
X1 = 0, X2 = 0
X1 = 1, X2 = 0
X1 = 0, X2 = 1
X1 = 1, X2 = 1
• Non-coherent receiver only sees position
– Demodulates only x1
– No Viterbi decoding required (easy since x1=bk)
– Achieves no coding gain, assumes bk = x1  Done.
• Coherent receiver demodulates position and phase
– Decodes x1 & x2
– Viterbi decoding used to estimate original bit, bk
– Achieves coding gain of original rate ½ code
Slide 24
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4-BOK (coherent)
constellation
2-PPM
constellation
Non-coherent receiver
cannot see these
2-PPM
constellation
OOK
constellation
• Encoding two coded bits requires a 4-point signal constellation
– Each axis represents one of two possible positions (orthogonal axes)
– Phase of pulse determines sign of constellation point on axis  4-BOK
• Non-coherent receiver is insensitive to phase – see only two points in
constellation  2-PPM
• Support for OOK receiver is possible by demodulating only one of the
two dimensions (i.e. just look at first position: pulse or not?)
Slide 25
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Transmitted Reference (TR)
• TR schemes simplify the channel estimation process
• Reference waveform available for synchronisation
• Potentially more robust (than non-coherent) under
SOP operation
• Supports both coherent/differentially-coherent
demodulation
• Multiple pulses can be used to increase throughput
• Implementation challenges:
– Analogue: Implementing delay value,
– delay mismatch, jitter
Slide 26
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Differential Encoding of Bits
b-1
0
b0
b1
b2
b3
b4
b5
0
1
1
0
0
1
-1
-1
+1
+1
-1
-1
+1
-1
+1
-1
+1
-1
Ts
Slide 27
Tx Bits
Reference Polarity
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Multiple access
• On top of this modulation scheme:
– Polarity hopping: repeat data at regular intervals,
but encoded with polarity sequence that is unique
for piconet
– Alternatives:
• Time hopping
• Ternary encoding sequence
• Note that PPM can be applied on a “per
pulse” basis or a “per symbol” basis (see 050130 and Backup slides)
Slide 28
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Symbol Format (1st realization)
Td
Tc
Tf
Ts
•Non-coherent receiver sees energy in one of the two halves
•Differentially coherent receiver sees phase differences
•Coherent receiver sees symbols drawn from 2-D signal space:
 0 (t ) 
1
N f Ep
p(t) and  1 (t ) 
1
N f Ep
p(t  Td )
Slide 29
Positive pulse
Negative pulse
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Bandwidth Usage
•
Flexible use of (multi-)bands
•
Signal bandwidth may be 500 MHz to 2 GHz
•
Bandwidth may change depending on application
and regulatory environment
•
Use of polarity randomization for spectral smoothing
•
Different bandwidth use options being considered
Slide 30
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Band Plan
BAND_ID
Lower frequency
Center frequency
Upper frequency
1
3168 MHz
3432 MHz
3696 MHz
2
3696 MHz
3960 MHz
4224 MHz
3
4224 MHz
4488 MHz
4752 MHz
4
4752 MHz
5016 MHz
5280 MHz
5
5280 MHz
5544 MHz
5808 MHz
6
5808 MHz
6072 MHz
6336 MHz
7
6336 MHz
6600 MHz
6864 MHz
8
6864 MHz
7128 MHz
7392 MHz
9
7392 MHz
7656 MHz
7920 MHz
10
7920 MHz
8184 MHz
8448 MHz
11
8448 MHz
8712 MHz
8976 MHz
12
8976 MHz
9240 MHz
9504 MHz
13
9504 MHz
9768 MHz
10032 MHz
14
10032 MHz
10296 MHz
10560 MHz
Slide 31
Mar. 2005
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Option: Linear Pulse Combination
• Spectral shaping by linear combination of delayed, weighted
pulses
– Adaptive determination of weight and delay
– Number of pulses and delay range restricted
– Can adjust to interferers at different distances
(required nulldepth) and frequencies
• Weight/delay adaptation in two-step procedure
• Initialization as solution to quadratic optimization problem
(closed-form)
• Refinement by back-propagating neural network
• Matched filter at receiver good spectrum helps coexistence
and interference suppression
Slide 32
Mar. 2005
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Spectral Shaping & Polarity Scrambling
Td = 10 ns
-120
-130
-140
-150
-160
-170
-180
Td = 20 ns
-190
-200
-210
-220
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
10
x 10
W/O Polarity Scrambling
Slide 33
W/ Polarity Scrambling
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Adaptive Frame Duration
• Advantage of large number of pulses per symbol:
– Smaller peak-to-average ratio
– Increased possible number of SOPs
• Disadvantage:
– Increased inter-frame interference
– In TR: also increased interference from reference pulse to
data pulse
• Solution: adaptive frame duration
– Feed back delay spread and interference to transmitter
– Depending on those parameters, TX chooses frame duration
Slide 34
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Ranging
Slide 35
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Ranging
•
Motivation :
– Benefit from high time resolution (thanks to signal bandwidth):
• Theoretically: 2GHz provides less than 20cm resolution
• Practically: Impairments, low cost/complexity devices should
support ~50cm accuracy with simple detection strategies
(better with high resolution techniques)
•
Approach :
– Use Two Way Ranging between 2 devices with no network
constraint (preferred); no need for time synchronization among
nodes
– Use One Way Ranging and TDOA under some network
constraints (if supported)
RTT
Asynchronous Ranging
TOF : Time Of Flight
RTT : Round Trip Time
SHR
TOF
Transmitted packets
SHR
k
Received packets
TOF
Payload
Payload
Pre-determined
delay time(T)
TOF = (RTT-2k-T)/2
SHR : Synchronization Header
Slide 36
SHR
SHR
Payload
Payload
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
TOA Delay Estimation - Non-Coherent
•
Use bank of integrators to determine coarse synchronisation “uncertainty”
region
–
•
Symbol synchronisation “uncertainty” region given by coarse synchronisation ( e.g., 4ns-20ns)
A refinement search is applied onto the uncertainty region by either
– further dividing it into narrower non overlapping regions for non-coherent refinement
(e.g., 1ns –> 4ns) or
– Coherent search with a template correlation
Integrator outputs
r (t )
 | r (t  kTRB ) |
2
E1
E2 ... E N 
k {0,1,.. N}
4ns  TRB  20 ns
TRB: the length of uncertainty region
N  T f / TRB
Energy
Analyzer
Detects the coarse
“uncertainty region”
k̂ LE
Leading Edge
Search Refinement
Range info
Slide 37
Performed within
the selected
uncertainty region
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
TOA Delay Estimation - Non-Coherent (cont’d)
•
•
The algorithm selects the maximum value integration window index and
then it searches backward to find the first integration value which crosses
an adaptively set threshold.
If there are no values crossing the threshold, the peak position is used for
the TOA estimation.
MES-SB based TOA Estimate
Searchback window
Strongest Path, energy block
Threshold based TOA Estimate
Threshold
N
0 1 2
Actual TOA
MES: Maximum Energy Search
TC: Threshold comparison
SB: Search Back
Contains leading
edge
MES based TOA Estimate
Slide 38
Mar. 2005
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Proposed Positioning Scheme
 Features
- Sequential two-way ranging is executed via relay transmissions
- PAN coordinator manages the overall schedule for positioning
- Inactive mode processing is required along the positioning
- PAN coordinator may transfer all sorts of information such as observed
- TDOAs to a processing unit (PU) for position calculation
P_FFD3
P_FFD2
TOA24
TOA34
RFD
PAN
coordinator
PU
TOA14
P_FFD : Positioning Full Function Device
RFD : Reduced Function Device
Benefits
P_FFD1
- It does not need pre-synchronization among the devices
- Positioning in mobile environment is partly accomplished
Slide 39
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Process of Proposed Positioning Scheme
TOA measurement
Slide 40
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doc.: IEEE 802.15-05-0158-00-004a
More Details for obtaining TDOAs
• Distances among the positioning FFDs are calculated from RTT
measurements and known time interval T
RTT12 = T + 2T12
T12 = (RTT12 – T)/2
RTT23 = T + 2T23
T23 = (RTT23 – T)/2
RTT13 = T12 + 2T + T23 + T13
T13 = (RTT13 – T12 – T23 – 2T)
• Using observed RTT measurements and calculated distances,
TOAs/TDOAs are updated
RTT34 = T34 + T + T34
TOA34 = (RTT34 - T)/2
RTT24 = T23 + T + T34 + T + T24
TOA24 = (RTT24 - T23 - TOA34 - 2T)
RTT14 = T12 + T + T23 + T + T34 + T + T14
TOA14 = (RTT14 - T12 - T23 - TOA34 - 3T)
TDOA12 = TOA14 – TOA24
TDOA23 = TOA24 – TOA34
Slide 41
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Position Calculation using TDOAs
• The range difference measurement defines a hyperboloid of
constant range difference
• When multiple range difference measurements are obtained,
producing multiple hyperboloids, the position location of the device
is at the intersection among the hyperboloids
A
TOATag_A
TDOAA_B
B
Tag
TOATag_C
C
TOATag_B
TDOAB_C
Ri , j  c  TDOAi , j  c  (TOAi  TOAj )  ( X i  x)2  (Yi  y)2  ( X j  x)2  (Y j  y ) 2
Slide 42
Mar. 2005
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Conclusions
•
Proposal based upon UWB impulse radio
– High time resolution suitable for precise ranging using TOA
– Modulation:
• Pulse-shape independent
• Robust under SOP operation
• Facilitates synchronization/tracking
• Supports multiple coherent/non-coherent RX architectures
•
System tradeoffs
– Modulation optimized for several aspects (requirements, performances,
flexibility, technology)
– Trade-off complexity/performance RX
•
Flexible implementation of the receiver
– Coherent, differential, non-coherent (energy collection)
– Analogue, digital
Fits with multiple technologies
– Easy implementation in CMOS
– Very low power solution (technology, architecture, system level)
•
Slide 43
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Backup slides
Slide 44
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PER in 15.4a Channel Model
Non-Coherent (Energy Collection) BPPM
2PPM - PER vs. E b / N0 - 15.4a Channel Models
0
10
Packet Error Rate
X1-CM8:
X2-CM1:
X3-CM5:
X4-CM9:
Framing format:
industrial NLOS
Residential LOS
Outdoor LOS
Agricultural Areas
Preamble SFD
LEN
(32 bits) (8 bits) (8 bits)
MHR+MSDU
(240 bits)
CRC
(16 bits)
• Simulations over 1000 channel responses
• BW = 2GHz – Integration Time = 80ns
• Implementation loss + Noise figure margin : 11 dB
• Max range is determined from:
 Required Eb/N0,
 Implementation margin
 Path loss characteristics
-1
10
-2
10
16
17
18
19
Eb / N0 [dB]
20
21
22
X1 (CM8)
X2 (CM1)
X3 (CM5)
X4 (CM9)
Case I: 250 kbps – PRP 250 ns
with 16 pre-integrations = 4 µs
Required Eb/N0
19.5 dB
20 dB
21 dB
21.5 dB
Max Range (I)
10.78 m
84.61 m
86.72 m
58.67 m
Case II: 250 kbps – PRP 500 ns
with 8 post-integrations
Max Range (II)
7.33 m
53.25 m
54.15 m
34.72 m
Slide 45
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
PER/BER in 15.4a Channel Model
DBPSK (RAKE)
DBPSK – PER vs. Eb/N0 – 15.4a Channel Models
0
BER vs Eb/N0 for binary modulations - 100 equivalent uncorrelated samples
10
ideal MRC BPAM solution
Differentially coherent BPAM
X1
X2
X3
X4
-1
10
-2
-1
10
BER
10
-3
PER
10
-4
10
-2
10
-5
10
0
5
10
15
Eb/N0 (dB)
Theoretical BER Curves – Integration Time = 50 ns
-3
10
10
11
12
13
14
15
16
Eb/N0 (dB)
Case I: 250 kbps – PRP 250 ns
with 16 pre-integration = 4 µs
Case II: 250 kbps – PRP 500 ns
with 8 post-integrations
17
18
19
20
Implementation loss and Noise figure margin : 11 dB
X1 (CM8)
X2 (CM1)
X3 (CM5)
X4 (CM9)
Required Eb/N0
18 dB
17.5 dB
18.5 dB
18.5 dB
Max Range (I)
12.66 m
116.70 m
120.27 m
90.84 m
Max Range (II)
9.18 m
79.34 m
81.23 m
58.67 m
Slide 46
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Link Budget:
Non-Coherent (Energy Collection) BPPM
Mandatory Value
(PRP = 4 µs)
Optional Value
(PRP = 500ns - 8 integrations)
250 kb/s
250 kb/s
-10.64 dBm
-10.64 dBm
0 dBi
0 dBi
3.873 GHz
3.873 GHz
44.20 dB
44.20 dB
29.54 dB @ d = 30 m
29.54 dB @ d = 30 m
0 dBi
0 dBi
Rx Power (PR = PT + GT + GR – L1 – L2)
-84.38 dBm
-84.38 dBm
Average noise power per bit: N = -174 + 10log10(Rb)
-120.02 dBm
-120.02 dBm
7 dB
7 dB
-113.02 dBm
-113.02 dBm
Minimum Eb/N0 (S)
14 dB
17.6 dB
Implementation Loss (I)
5 dB
5 dB
9.64 dB
6.04 dB
-94.02 dBm
-90.42 dBm
Parameter
Peak Payload bit rate (Rb)
Average Tx Power Gain (PT)
Tx antenna gain (GT)
f’c: (geometric frequency)
Path Loss @ 1m: L1 = 20log10(4..f’c / c)
Path Loss @ d m: L2 = 20log10(d)
Rx Antenna Gain (GR)
Rx noise figure (NF)
Average noise power per bit (PN = N + NF)
Link Margin (M = PR - PN – S – I)
Proposed Min. Rx Sensitivity Level
Slide 47
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Link Budget: DBPSK (RAKE)
Mandatory Value
(PRP = 4 µs)
Optional Value
(PRP = 500ns - 8 integrations)
250 kb/s
250 kb/s
-10.64 dBm
-10.64 dBm
0 dBi
0 dBi
3.873 GHz
3.873 GHz
44.20 dB
44.20 dB
29.54 dB @ d = 30 m
29.54 dB @ d = 30 m
0 dBi
0 dBi
Rx Power (PR = PT + GT + GR – L1 – L2)
-84.38 dBm
-84.38 dBm
Average noise power per bit: N = -174 + 10log10(Rb)
-120.02 dBm
-120.02 dBm
7 dB
7 dB
-113.02 dBm
-113.02 dBm
Minimum Eb/N0 (S)
13 dB
16 dB
Implementation Loss (I)
5 dB
5 dB
10.64 dB
7.64 dB
-95.02 dBm
-92.02 dBm
Parameter
Peak Payload bit rate (Rb)
Average Tx Power Gain (PT)
Tx antenna gain (GT)
f’c: (geometric frequency)
Path Loss @ 1m: L1 = 20log10(4..f’c / c)
Path Loss @ d m: L2 = 20log10(d)
Rx Antenna Gain (GR)
Rx noise figure (NF)
Average noise power per bit (PN = N + NF)
Link Margin (M = PR - PN – S – I)
Proposed Min. Rx Sensitivity Level
Slide 48
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Framing – 802.15.4 Compatible
Octets
PHY layer
4
1
1
32
Preamble
SFD
Frame
length
PSDU = MPDU
PHR
PSDU (PHY Service Data Unit)
SHR
PPDU (PHY Protocol Data Unit)
Beacon slot
0
BP
1
2
CAP slot
3
4
5
CAP
6
7
CFP slot
8
BP : Beacon Period
CAP : Contention Access Period
CFP : Contention Free Period
IP : Inactive Period (optional)
9 10 11 12 13 14 15
CFP
Superframe Duration
Beacon Interval
Slide 49
IP
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Throughput
Data Frame (32 octet PSDU)
Bytes
4
PHY layer Preamble
SHR
1
1
32
SFD
Frame
length
PSDU = MPDU
PHR
PSDU (PHY Service Data Unit)
ACK Frame (5 octet PSDU)
Bytes
PHY layer Preamble
•
1
1
5
SFD
Frame
length
PSDU
PHR
PSDU
SHR
PPDU (PHY Protocol Data Unit)
Tdata
4
PPDU (PHY Protocol Data Unit)
T_ACK
Tack
IFS
Numerical example (high-band)
•
Preamble + SFD + PHR = 6 octets
•
Tdata = 1.216 ms
•
T_ACK = 50 ms (turn around time requested by IEEE 802.15.4 is 192ms)
•
Tack = 0.352 ms
•
IFS = 100μs
 Throughput = 32 octets/1.718 ms = 149 kb/s
 Average data-rate at receiver PHY-SAP 250 kb/s (Basic Mode)
Slide 50
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Saving Power
•
Power Saving techniques achieved by combining advantages offered at 3 levels:
– Technology (best if CMOS)
– Architecture (flexible schemes provided by the TH+pulse modulation)
– System level (framing, protocol usage)
•
Selected techniques used in one existing realization (see proof of concept slides)
– Low-duty cycle Episodic transmission/reception
• Scheduled wake-up
• 80ms RTOS tick
– Ad-hoc networking using multi-hop
• Special rapid acquisition codes / algorithm
• Matchmaking further reduces acquisition time
– Multi-stage time-of-day clock
• Synchronous counter / current mode logic for highest speed stages
• Ripple counter / static CMOS for lowest speed stages
– Compute-intensive correlation done in hardware
Slide 51
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
ENERGY Spread in CM1
• PDF of TOA estimation errors are illustrated for MES
at various EbN0
– CM1, integration interval 4ns, Tf=200ns (results will be updated for
Tf=240ns)
Slide 52
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Ranging Simulation Settings
Notations and Terms
Definition
Value in Simulations
Tf
Pulse repetition interval, frame
Nb
Number of blocks within a Tf
50
Nc
Number of refinement intervals within a Tf
400
TH{}
POL{}
200ns
Time hopping sequence in chips
{h1, ...., h5}
Polarity codes
{p1, ..., p5}
N1
Number of frames in the 1st-step
50
N2
Number of frames in the refinement
30
BW
Bandwidth
C
2GHz
Number of correlators (refinement stage)
Note: Results are to be provided when Tf is set to 240ns.
Slide 53
10
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Ranging Results
• IEEE 802.15.4a CM1-Residential LOS
True Distance (m)
One-way ranging error
(confidence level)
25m
8cm (97%)
30m
8cm (~90%)
Round Trip ranging error
(with no drift compensation)
– ~16cm (0.088ms),
no clock drift
– ~17.1cm (1ppm)
– ~20.1cm (4ppm)
– ~26cm (10ppm)
– ~56cm (40ppm)
Slide 54
IEEE 802.15-05-0158-00-004a
Two Way Rangingdoc.:
(TWR)
Mar. 2005
Main Limitations / Impact of Clock Drift on Perceived Time
TReply  A  f B 
~
TOF A  TOF A 1  f A  
21  f B 
. f 0 Is the frequency offset relative to the nominal ideal frequency
Range estimation is affected by :
• Relative clock drift between A and B
250 kbps, 38 bytes
PPDU
f0
500 kbps, 9 bytes
PPDU
• Prescribed response delay
f/f \ Treply
(max error)
1408 ms
1226 ms
336 ms
154 ms
• Clock accuracy in A and B
4 ppm
1.69 m
1.47 m
0.40 m
0.18 m
25 ppm
10.56 m
9.19 m
2.52 m
1.15 m
40 ppm
16.9 m
14.7 m
4.0 m
1.8 m
•Channel response (weak direct path)
Example using Imm-ACK SIFS of 15.4 and 15.3
of respectively 192us and 10 us
and PPDU size of respectively 38 and 9 bytes
Simple immediate TWR made unusable with reasonnable crystal accuracies. Solution is :
• Performing fine drift estimation/compensation
• Benefiting from cooperative transactions Slide
(estimated
clock ratios …)
55
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Antenna
Feasibility
Return Loss
Capacitive Dipole and Various Bowtie Antennas
0
-5
measured dipole
measured v2
measured v3
simulated v2
simulated v3
-20
-25
-30
-35
9.96
9.24
8.52
7.79
7.07
6.35
5.62
4.9
4.18
3.45
2.73
-40
2.01
dB
-10
-15
GHz
55 mm
40 mm
Bowtie antenna
Slide 56
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
“Proof-of-Concept” (1)
Non-coherent Transceiver
Non-coherent,
Energy Collection Receiver
Fref
TX
DLL
PG
DIGITAL
LOGIC
DLL
CM
33 MHz
UWB
ANTENNA
UWB
PG
SWITCH
528 MHz
x16
5 Mbps BPPM
350 ps pulse train
with long scrambling code
Oscilator Generator
Control
line
DIGITAL
CONTROL
LOGIC
Flagrst
1
....
Flagrst
8
2
Energy
collection
/2
A/D
Converter
VGA
LNA
( )
DETECTION
BIT
DECISION
(digital)
GAIN SELECTION
RX
Slide 57
BASEBAND
DSP
(decision logic)
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
“Proof-of-Concept” (2)
Non-coherent Transceiver
UWB-IR BPPM Non-Coherent Transceiver Implementation
UWB Transmitter
400 μm x 400 μm
0.35 μm CMOS
UWB Transceiver
Test architecture <10 mm2
0.35 μm SiGe Bi-CMOS
Slide 58
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
“Proof-of-Concept” (3):
Transmitter - Lower Band
P-Channel Drivers
Delay
Buffers
N-Channel Drivers
N-C
UWB Transmitter chip for
generating impulse doublets
Slide 59
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
VGC Amp
DACs
32 Time-Integrating
Correlators
PLL Loop Filter
DACs
Code
Sequence
Generators
“Rails” for testing
analog circuits
LF RTC
High-Frequency
Real Time Clock
“Proof-of-Concept” (4):
Receiver - Lower Band
Coherent UWB Receiver with
multiple time integrating correlators
Slide 60
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
“Proof-of-Concept” (5)
High Speed Coherent Circuit Elements
RF front end chips in CMOS 0.13mm, 1.2V
20 GHz digitizer for UWB
20 GHz DLL for UWB
3-5 GHz LNA
Chip and layout
Slide 61
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Backup Slides
Slide 62
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Synchronisation Preamble
Correlator output for synchronisation
• Code sequences has good autocorrelation properties
• Preamble is constructed by repeating ‘0000’ symbols
• Long preamble is constructed by further symbol repetition
Slide 63
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Frame Format
Octets:
2
MAC
Sublayer
1
0/4/8
Frame
Seq. # Address
Cont.
MHR
Octets:
PHY
Layer
4?
Preamble
SHR
1
SFD Frame
Length
MPDU
PHR
PSDU
PPDU
Slide 64
Data
Payload
MSDU
Data: 32 (n=23)
1
n
For ACK: 5 (n=0)
2
CRC
MFR
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Code Sequence
Properties & Performance
1.
2.
AWGN Performance
Multipath Performance (in Appendix)
I.
For Coherent Symbol Detector
II.
For Non-coherent Symbol Detector
III. For Differential Chip Detector
IV. For Energy Detector
Slide 65
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Auto Correlation Properties for
Coherent/Non-Coherent Symbol Detector
Slide 66
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Cross Correlation Properties for
Coherent/Non-Coherent Symbol Detector
TxSeqSet * RxSeqSet' (Mode 1) =
TxSeqSet * RxSeqSet' (Mode 2) =
Slide 67
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Multipath Performance for
Coherent Symbol Detector
Slide 68
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Multipath Performance for
Non-Coherent Symbol Detector
Slide 69
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Auto Correlation Properties for
Differential Chip Detector
Slide 70
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Cross Correlation Properties for Differential
Chip Detector
DifferentialChip(TxSeqSet) *
DifferentialChip(RxSeqSet)’ (Mode 2) =
DifferentialChip(TxSeqSet) *
DifferentialChip(RxSeqSet)’ (Mode 1) =
Slide 71
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Multipath Combining for
Differential Chip Detector





Re x1,n 1  x1*,n  Re x2,n 1  x2*,n  Re x3,n 1  x3*,n
x 1, n
x 2,n
x
x1,n 1 2,n 1
x 3,n
x 3,n 1
Slide 72

Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Multipath Performance for
Differential Chip Detector
Simulation Results to be available later
Slide 73
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Non-Coherent Receiver Architectures (Mode
1)
BPF
( )2
LPF /
integrator
ADC
Soft
Despread
Sample Rate 1/Tc
• Energy detection technique rather than coherent
receiver, for low cost, low complexity
• Soft chip values gives best results
• Oversampling & sequence correlation is used to
recovery chip timing recovery
• Synchronization fully re-acquired for each new packet
received (=> no very accurate timebase needed)
Slide 74
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Auto Correlation Properties for
Energy Detection Receiver
Slide 75
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Cross Correlation Properties for
Energy Detection Receiver
TxSeqSet * RxSeqSet ' =
Slide 76
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Multipath Performance for
Energy Detector
Slide 77
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Basic Data Rate Throughput
(Low Rate Modes)
ACK
Data Frame (38 bytes)
t ACK
LIFS
Tframe
(Time Slot for Multiple Piconet)
• Useful data rate calculation for 32 byte PSDU (Xo = 0.75 Mbps)
• Symbol Period = 1.33us
– Data frame time : 38 x 8 / 0.75= 405.3 µsec
– ACK frame time : 11 x 8 / 0.75 = 117.3 µsec
– tACK (considering 15.4 spec) : 192 µsec
– LIFS (considering 15.4 spec) : 640 µsec
– Tframe = 1355 µsec
– Useful Basic Data Rate = 189.0 kbps
Slide 78
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Basic Data Rate Throughput
(High Rate Modes)
ACK
Data Frame (38 bytes)
t ACK
LIFS
Tframe
(Time Slot for Multiple Piconet)
• Useful data rate calculation for 32 byte PSDU (Xo = 3 Mbps)
• Symbol Period = 1.33us
– Data frame time : 38 x 8 / 3 = 101.3 µsec
– ACK frame time : 11 x 8 / 3 = 29.3 µsec
– tACK (considering 15.4 spec) : 192 µsec
– LIFS (considering 15.4 spec) : 640 µsec
– Tframe = 963 µsec
– Useful Basic Data Rate = 265.9 kbps
Slide 79
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Basic Data Rate Throughput
(High Rate Modes)
ACK
Data Frame (38 bytes)
t ACK
LIFS
Tframe
(Time Slot for Multiple Piconet)
• Useful data rate calculation for 127 byte PSDU (Xo = 3 Mbps)
• Symbol Period = 1.33us
– Data frame time : 127 x 8 / 3 = 354.7 µsec
– ACK frame time : 11 x 8 / 3 = 29.3 µsec
– tACK (considering 15.4 spec) : 192 µsec
– LIFS (considering 15.4 spec) : 640 µsec
– Tframe = 1216 µsec
– Useful Basic Data Rate = 853.5 kbps
Slide 80
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Link Budget
Slide 81
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
BER Performance in AWGN Channel
10-1
MRC Solution (coherent)
Differential Solution
Energy Collection solution in OOK
Transmitted Reference (one pulse)
BER
10-2
10-3
10-4
10-5
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20
Eb/N0
-3 dB : the “reference” is not in the same PRP !
p packet
 1  1  bit error 
N
error
PER = 1% with 32 bytes PSDU  acceptable BER 4x10-5 with no channel coding
Slide 82
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Positioning Scenario Overview
Slide 83
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Positioning Scenario Overview
 Case 1
• Using static reference nodes in
relatively large scaled cluster :
Cluster 1
– Power control is required
– Power consumption increases
– All devices in cluster must be in
inactive data transmission mode
PAN Coordinator
FFD
 Case 2
RFD
Positioning FFD(P_FFD)
• Using static and dynamic nodes
in overlapped small scaled subclusters :
– Sequential positioning is executed
in each sub-cluster
– Low power consumption
– Associated sub-cluster in
positioning mode should be in
inactive data transmission mode
Cluster 1
Slide 84
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Positioning Scenario for Star topology
• Star topology
– PAN coordinator activated mode
• Positioning all devices
• Re-alignment of positioning FFD’s list is not
required
– Target device activated mode
• Positioning is requested from some device
• Re-alignment of positioning FFD’s list is required
PAN
coordinator
측위 용
FFD2
FDD
P_FFD1
P_FFD3
P_FFD2
측위용
FFD1
PAN
coordinator
RFD3
RFD1
측위 용
FFD3
RFD2
RFD
Broadcasting
to all P_FFDs
S_addr.
S_addr.
S_addr.
S_addr.
S_addr.
PAN_co.
P_FFD1
P_FFD2
P_FFD3
T_RFD1
D_addr.
D_addr.
D_addr.
D_addr.
P_FFD1
P_FFD2
P_FFD3
T_RFD1
P_addr.
P_addr.
P_addr.
P_addr.
P_FFD1
P_FFD2
P_FFD3
T_RFD1
P_FFD2
P_FFD3
T_RFD1
P_FFD3
T_RFD1
T_addr.
T_addr.
T_addr.
T_RFD1
T_RFD1
T_RFD1
Slide 85
S_addr. : Source Address
D_addr. : Destination Address
P_addr. : Positioning Address
T_addr. : Target Address
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Positioning Scenario for
Cluster-tree Topology
RFD2

Cluster-tree topology
RFD4
RFD1
RFD0
FFD0
RFD1
P_FFD1
FFD1
RFD3
RFD3
P_FFD2
FFD1
PAN
coordinator
RFD4
FFD0
RFD6
FFD1
RFD2
P_addr.
P_FFD3
RFD7
RFD5
P_FFD3
addition
P_FFD3
PAN
coordinator
P_FFD1
P_FFD2
P_FFD3
RFD
Broadcasting
to all P_FFDs
N_addr.
N_P_addr.
S_addr.
S_addr.
S_addr.
S_addr.
S_addr.
FFD0
FFD1
RFD6
P_FFD2
P_FFD1
PAN_co.
P_FFD1
P_FFD2
P_FFD3
T_RFD5
D_addr.
D_addr.
D_addr.
D_addr.
P_FFD1
P_FFD2
P_FFD3
T_RFD5
P_addr.
P_addr.
P_addr.
T_addr.
P_FFD1
P_FFD2
P_FFD3
T_RFD5
P_FFD2
P_FFD3
re-arragement
P_FFD3
T_addr.
T_addr.
T_addr.
T_RFD5
T_RFD5
T_RFD5
Slide 86
S_addr. : Source Address
D_addr. : Destination Address
P_addr. : Positioning Address
T_addr. : Target Address
N_addr. : Neighbor Address
N_P_addr. : Neighbor Positioning Address
FFD2
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Ranging Accuracy Improvement
• Technical requirement for positioning
– “It can be related to precise (tens of centimeters) localization in some
cases, but is generally limited to about one meter ”
• Parameters for technical requirement
– Minimum required pulse duration :
1[m]
 3.333 [nsec]
3 10 8 [m / sec]
– Minimum required clock speed for the correlator in the conventional
coherent systems
1
 300 [ MHz ]
3.333 [nsec]
High Cost !
★ Fast ADC clock speed in the conventional coherent receiver
is required for the digital signal processing
Slide 87
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Analog Energy Window Bank (1)
• Digital signal processing with fast clock can be replaced by
using analog energy window bank with low clock speed
• Why analog energy window bank?
– Conventional single energy window may support the energy detection
for data demodulation in the operation mode
– However, this cannot guarantee the correct searching of the signal
position in the timing mode (that also means the ambiguity of ranging
accuracy)
• Analog energy window bank can sufficiently support timing and
calibration as well as operation mode
–
–
–
–
Widow Bank Size : ~4 nsec (smallest pulse duration)
The number of energy windows in a bank : 11
Operation clock speed of each energy window : 24 MHz
Number of the required energy windows depends on the power delay
profile of the multipath channel (effective multipath components)
Slide 88
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Analog Energy Window Bank (2)
Integrator Bank
for Timing and
Calibration Mode

2nsec
()2 dt
Integrator Bank
for Operation Mode
(Demodulation)
Size of the Integrated Bank (S)
2nsec

2nsec
()2 dt

()2 dt
2nsec

2nsec
Buffer

Buffer

()2 dt
Buffer
()2 dt
2nsec
()2 dt
Buffer
FirstEstimating
Path Estimation
or
Averaging
and
Calibration
Bit “1”
Slide 89
Threshold
Comparison
Bit “0”
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Modifying MAC
Slide 90
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
• Features
Modifications of
MAC Command Frame (1)
– Frame control field
• frame type : positioning (new addition using a reserved bit)
– Command frame identifier field
• Positioning request/response (new addition)
– Positioning parameter information field
• Absolute coordinates of positioning FFDs
• POS range
• List of positioning FFDs and target devices
• Power control
• Pre-determined processing time (T)
Octets : 2
1
0/4/8
1
variable
Frame
control
Sequence
number
Addressing
fields
command
frame
identifier
Positioning
parameter
MAC payload
MHR
Slide 91
Command
payload
2
FCS
MFR
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Modifications of
MAC Command Frame (2)
• Frame Control
bits : 0~2
3
4
5
6
7~9
10~11
12~13
14~15
Frame
type
Security
enabled
Frame
pending
Ack.
request
IntraPAN
Reserved
Dest.
addressing mode
Reserved
Source
addressing mode
• Command frame identifier
Frame type value
Description
000
Beacon
001
Data
Command frame
identifier
Command frame
010
Acknowledgment
0x01
Association request
011
MAC command
0x02
Association response
100
Positioning
0x03
Disassociation notification
101~111
Reserved
0x04
Data request
0x05
PAN ID conflict notification
0x06
Orphan notification
0x07
Beacon request
0x08
Coordinator realignment
0x09
GTS request
0x0a
Positioning request
0x0b
Positioning response
0x0c~0xff
Reserved
• Positioning parameter
Fixed
coordinate
POS
range
positioning
FFDs
Address &
Target devices
lists
Predetermined
processing
time(T)
Power
Control
Slide 92
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Design Parameters (1)
•
Motivation:
–
–
–
•
Flexible waveform
Simple
Compatible with multiple coherent/non-coherent receiver schemes
Large Bandwidth
•
•
•
•

•
(+) Higher transmit power
(+) improved time resolution
(-) Increased design complexity
(-) Less stringent requirements on out of band interference filtering
Signal BW of 500 MHz - 2 GHz in Upper bands
Signal BW of 700 MHz in 0 to 960 MHz Lower band (low band)
Long Pulse Repetition Period
• (+) more energy per pulse (easier to detect single pulse)
• (+) Lower inter-pulse interference due to channel delay spread
• (-) Higher peak voltage requirements at transmitter
• (-) Longer acquisition time
 Frame duration between 40ns (first realization) and 125ns (second realizations). Higher values
for the frame duration have been mentioned. Further discussions are required to fix the values
Slide 93
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Design Parameters (2)
•
Simple modulation schemes:
• BPPM combined with Transmitted Reference
•
Channelization :
• Coherent schemes: Use of TH codes and polarity codes
• Non-coherent schemes: Use of TH codes (polarity codes for spectrum smoothing
only)
•
Long TH code length
• (+) higher processing gain, robustness to SOP operation
• (-) Lower bit-rate
• (-) Longer acquisition time, shorter frame size (synch. phase)
 TH code length 8 or 16
TH code : binary position (delay of 0 or τΔ ), bi-phase
For first realization, higher-order TH with shorter chip duration (multiples of
2ns) can be used. This is under discussion
Slide 94
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Transmission
• Basic idea: use modulation scheme that allows coherent,
differentially coherent, and incoherent reception
• Combine BPPM with more sophisticated TR scheme
– Non-coherent receiver sees BPPM with pulse stream per bit
– More sophisticated receiver sees BPPM (1 bit) plus bits carried in
more sophisticated modulation scheme (e.g. extended TR)
• Advantages:
– Coherent, differential and non-coherent receiver may coexist
– reference can be used for synch and threshold estimation
• Concept can be generalized to N-ary TR system
Slide 95
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Waveform Design
• Coexistence of coherent and non-coherent architectures
• Combine BPPM with BPSK
• Divide each symbol into two 125 ns BPPM slots (250 ns symbol)
• In either slot transmit a signal that can be received with a variety
of receivers: differentially coherent or coherent receivers.
• Non-coherent receivers just look for energy in the early or late
slots to decode the bit.
• Other receivers understand the fine structure of the signal.
Slide 96
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Waveform Design
• Two possible realizations:
– The whole symbol (consisting of N_f frames) is
BPPM-modulated.
– Have a 2-ary time hopping code, so that each
frame has BPPM according to TH code
Slide 97
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
First Realization
Slide 98
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Second Realization
Ts
« 11 »
2-PPM + TR base
M=2
(with two bits/symbol)
One bit/symbol also
Possible !!!
« 01 »
« 10 »
« 00 »
(coherent decoding possible)
2-PPM + 16 chips 2-ary TH code
This is a time-hopping that can be exploited by non-coherent receiver
Time hopping code is (2,2) code of length 8 or 16
Effectively 28 or 216 codes to select for channelization for non-coherent scheme
Slide 99
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Time Hopping Impulse Radio (TH-IR) - Principle
+1
Tc
Tf
Ts
-1
• Each symbol represented by sequence of very short pulses (see
also Win & Scholtz 2000)
• Each user uses different sequence (Multiple access capability)
•Bandwidth mostly determined by pulse shape
Slide 100
Mitigation of peak voltage through multi pulses
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Tf=PPI
ppV = peak-to-peak voltage
M=1
IS « EQUIVALENT » TO
Tf=PPI
M=4
ppV/2
Tf=PPI
M=2
ppV/sqrt(2)
Slide 101
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Coexistence of Different Receiver
Architectures
• Want waveform that allows TR reception
without penalizing coherent reception
• That is achieved by special encoding and
waveform shaping within each frame. Does
not affect the co-existence of coherent/noncoherent receivers
Slide 102
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Basic Properties
• Use of Doublets with memory from previous
bit. (Encoding of reference pulse with
previous bit)
– Agreed on 20ns separation between pulses
– Extensible to higher order TR for either reducing
the penalty in transmitting the reference pulse or
increasing the bit rate?
– Also allows the use of multi-DOUBLET
Slide 103
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Differential Encoding of Bits
b-1
0
b0
b1
b2
b3
b4
b5
0
1
1
0
0
1
-1
-1
+1
+1
-1
-1
+1
-1
+1
-1
+1
-1
Tx Bits
Reference Polarity
Ts
Note: This slide is meant to describe the encoding of data on the reference
pulse and data pulse in the basic modulation format. For simplicity we have
omitted the multipulse/multiframes per symbol structure.
Slide 104
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Total Modulation Scheme (First Realization)
THE KEY SLIDE OF THE PROPOSAL: this is the modulation format that allows
Coherent, differentially coherent, and non-coherent demodulation at once
Slide 105
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Higher-order modulation
D
D
D
τdelay +τΔ
«1»
Basic Mode
(as seen by non-coherent)
D
D
D
τdelay +τΔ
«11»
Enhanced Mode 1
«10»
Pulse Shift,
polarity invert
τΔ + τdelay
TH Code
Data
1,1
1,1
τΔ + τdelay
1,1
1,1
τΔ
τdelay
0,1
1,1
τΔ
τdelay
0,0
1,1
Slide 106
τΔ + τdelay
1,0
1,1
τΔ + τdelay
0,1
0,0
TH Pattern
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Comments on Transmitted Signal
• Frame period for solution 2 is Tframe = (Np * D) + τΔ + τdelay
– Τdelay is some allowance for channel delay spread
• Frame period could be dynamic modified dependant on
– the estimated channel delay spread or
– ability of receiver to cope with delay spread
• Symbol period is length of the TH code x Tframe
– Upper Band Nominally 250 ns x 16 = 4 µs
– Lower Band Nominally 500 ns x 8 = 4 µs
• Realistic Receiver structures exist for multi-pulse TR schemes
(see back-up slides)
Slide 107
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
BER Performance in AWGN Channel
Slide 108
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Antenna Practicality
• Bandwidth: 3 GHz-10 GHz
z
antenna hat
Ø 24 mm
• Form factor
• Omni-directional
q
7 mm
y
j
0
M.S.
measured
-2
x
-4
-6
-8
-10
-12
-14
-16
-18
-20
-22
-24
-26
2
3
4
5
6
7
8
9
10
11
12
frequency (GHz)
Slide 109
ground plane
Ø 80 mm
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Positioning from TDOA
Anchor 3
3 anchors with known
positions (at least) are
required to find a 2D-position
from a couple of TDOAs
(xA3,yA3)
Anchor 2
(xA2,yA2)
Mobile
Estimated Position
Measurements
~ ~
d32 , d31
d 32 
d 31 
x
x
~
xM , ~
yM
Specific Positioning
Algorithms
A3
 xM
A3
 xM
  y
  y
(xm,ym)
A3
 yM
A3
 yM
2
2


2
2


x
x
A2
 xM
A1
 xM
Slide 110
Anchor 1
  y
  y
2
A2
2
A1
 yM
 yM


2
2
(xA1,yA1)
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
TR BPPM Scheme Comparison
Slide 111
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Assumptions and Notes
• Results are theoretical calculations
• Assumes ideal ”impulse” UWB pulses in
AWGN channel
• Different TR-BBP options are considered with
different number of pulses per pulse train
• Multipath fading simulations can be performed
to back up theory
Slide 112
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Pulse repetition structures
TR BPPM with doublets (Scheme 1)


Slide 113
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Pulse repetition structures
TR BPPM single reference (Scheme 2)


Slide 114
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Pulse repetition structures
Auto Correlation BPPM with doublets (Scheme 3)

Slide 115

Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Pulse repetition structures
Auto Correlation BPPM single reference (Scheme 4)


Slide 116
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Pulse repetition structures
Auto Correlation BPPM alternate (Scheme 5)


Slide 117
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Parameters
• PPI slot - slot inside each TH chip containing
a burst of pulses including reference pulses
(ref. slides from Laurent / CEA)
• Np represents the number of pulses in each
PPI slot
• The energy E per PPI slot is kept constant
• The pulse energy Ep = E/Np
• TW represent the time-bandwidth product
Slide 118
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Ep/N0 degradation versus number of pulses per pulse train
Slide 119
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Ep/N0 degradation versus Time/Bandwidth product
Slide 120
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Ep/N0 degradation versus number of pulses per pulse train
Slide 121
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Conclusions
• Scheme 5 - “AC Alternate” performs better then all the other
pulse repetition structures.
• AC generally performs better than TR
• “AC alternate” and “AC with doublets” have the advantage of
requiring only a single delay line.
• Scheme 5 - “AC Alternate”, was proposed at Monterey meeting
in January.
• Criticism was given based on ”accumulated noise” in noisecross-noise-cross-noise... Products”.
• Seems to outperform other schemes with simple analysis
• Also more readily implementable since fixed delay line can be
used.
Slide 122
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Channel / Delay Estimation
Coherent Approach
Slide 123
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Channel / Delay Estimation
Coherent Approach
• Swept delay correlator
• Principle: estimating only one channel sample per symbol.
Similar concept as STDCC channel sounder of Cox (1973).
• Sampler, AD converter operating at SYMBOL rate (1.2
Msamples/s)
• Requires longer training sequence
• Two-step procedure for estimating coefficients:
– With lower accuracy: estimate at which taps energy is
significant
– With higher accuracy: determine tap weights
• “Silence periods”: for estimation of interference
Slide 124
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Optimal Energy-Threshold Analysis (CM-1)
•
Optimal normalized threshold (normalized with respect to the difference between
the maximum and minimum energy blocks) changes with Eb/N0 and block size.
•
Smaller thresholds are required in general at high Eb/N0, while larger thresholds
at lower SNR values
MAE
Mean Absolute Error in
detecting leading energy
block with simple
threshold crossing (1000
channel realizations)
Eb/N0 : {8 --- 26dB}
Slide 125
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Proposed RAKE -- Coherent Receiver
Channel Estimation
Rake Receiver
Finger 1
Demultiplexer
Rake Receiver
Finger 2
Summer
Sequence
Detector
Convolutional
Decoder
Data
Sink
Rake Receiver
Finger Np
• Addition of Sequence Detector – Proposed modulation may be viewed
as having memory of length 2
• Main component of Rake finger: pulse generator
• A/D converter: 3-bit, operating at symbol rate
• No adjustable delay elements required
Slide 126
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Proposed Transmitted Reference Receiver –
Differentially Coherent
•Addition of Matched Filter prior to delay and correlate operations
improves output signal to noise ratio and reduces noise-noise
cross terms

Matched
Filter
Td
SNR of decision
statistic
Slide 127
0

Convolutional
Decoder
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Differentially-Coherent/Non-Coherent Receiver Architecture
Basic Mode and Enhanced Mode 1
Controlled
Integrator
Band Matched
r(t)
x2
BPF
RAZ
LNA
BPPM Demodulation
branch
Dump
Latch
RAZ
DUMP
ADC
Tracking
Threshol
ds
setting
Ranging branch
ADC
Dump
Latch
Delay
Controlled
Integrator
TR Demodulation
branch
TR
BPPM
Synch
Trigger
Recyle this branch for Enhanced Data Rate Modes
Slide 128
Energy Analyzer
Block index for
acquisition
reference
Leading-edge
refinement search
Range info
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
De-spreading TH Codes
Band Matched
LNA
r(t)
BPF
TH
Sequence Matched
Filter
Bit Demodulation
ADC
Case I - Coherent TH despreading
Band Matched
LNA
r(t)
Bit Demodulation
BPF
b(t)
soft
info
TH
Sequence Matched
Filter
Case II – Non-coherent / differential TH despreading
Slide 129
ADC
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Bandwidth Usage – 2GHz option (2/4)
ISM
Band
Upper Band
1
Lower band
0.96
ISM
Band
3.1
Upper Band
3
Upper Band
2
5.1
6.0
Slide 130
8.0 8.1
10.1
GHz
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Bandwidth Usage -500 MHz Option (3/4)
ISM
Band
ISM
Band
Upper Bands
5 - 12
Upper Bands
1-4
Lower band
0.96
3.1
5.1 6.0
Slide 131
8.0 8.1
10.1
GHz
Mar. 2005
doc.: IEEE 802.15-05-0158-00-004a
Bandwidth Usage –Variable Option (4/4)
ISM
Band
ISM
Band
Upper Bands
5 - 12
Upper Bands
1-4
Lower band
0.96
3.1
5.1 6.0
Slide 132
8.0 8.1
10.1
GHz