March 2010
doc.: IEEE 802.22-10/0054r1
OFDMA-based Terrestrial Geolocation
Authors:
Name
Company
Address
Phone
email
Gerald Chouinard
Communications
Research Centre,
Canada
3701 Carling Ave.
Ottawa, Ontario
Canada K2H 8S2
(613) 998-2500
[email protected]
Ivan Reede
Amerisys Inc.
Montreal, Canada
(514) 620-8652
[email protected]
Abstract
This contribution summarizes the results of a study done at CRC on the validity and feasibility of including a terrestrial
triangulation method for geolocation of WRAN devices based on a precise propagation delay measurement scheme integrated
to the 802.22 standard. This is in response to comment #1160 and #1161 to the 802.22 Draft 2.0.
Notice: This document has been prepared to assist IEEE 802.22. 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 grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE
Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit
others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.11.
Patent Policy and Procedures: The contributor is familiar with the IEEE 802 Patent Policy and Procedures <http://standards.ieee.org/guides/bylaws/sb-bylaws.pdf>, including the
statement "IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to
patents essential for compliance with both mandatory and optional portions of the standard." Early disclosure to the Working Group of patent information that might be relevant to the
standard is essential to reduce the possibility for delays in the development process and increase the likelihood that the draft publication will be approved for publication. Please notify the
Chair Carl R. Stevenson <[email protected]> as early as possible, in written or electronic form, if patented technology (or technology under patent application) might be incorporated into a
draft standard being developed within the IEEE 802.11 Working Group. If you have questions, contact the IEEE Patent Committee Administrator at <[email protected]>.
Submission
Slide 1
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Review of geolocation technologies and algorithms
Technologies/
Algorithms
Advantage(s)
Radio Beacons
Simplicity, Low cost
GPS
Prevalent technology
AMPS
CDMA
Interference robustness
GSM
Timing accuracy
Schmidl-Cox
Accurate symbol timing
Minn
Accurate symbol timing
Morelli-Mengali
Amerisys
Amerisys|CRC
Submission
Accurate symbol timing,
use of one training
symbol
No. Tx interruption for
geolocation
No. Tx interruption for
geolocation
Disadvantages
Industry Status
Clear vision requirement, Very
coarse
Inaccuracy with environment
factors, susceptible to multipath, slow operation
Hard to implement
Power control issue
System design change
requirement
Flat region ambiguity, Tx
interruption for geolocation
Flat region ambiguity, Tx
interruption for geolocation
Flat region ambiguity, Tx
interruption for geolocation
Hardware complexity
OLD technology,
Aviation use
Phase ambiguity (+2kπ)
In progress
In use
Obsolete
In use
In use
In progress
In progress
In progress
Phase ambiguity resolved by
FFT/IFFT and correlation with In progress
complex prototype function
Slide 2
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between Base Station and CPE
(Coarse Time Difference of Arrival: TDOA)
RNG-RSP >
BS A1
Downstream
CPE
Upstream
< RNG-REQ
1.
CPE synchronizes with BS and is in phase-lock with the RF carrier.
The sampling frequency (≈ 8/7*BW) is derived from the same clock (§8.12.1)
BS and CPE carry out normal association and ranging (RNG-REQ and RNGRSP, §6.9.5 and §6.9.6) and adjust the advance A1 so that all CPE upstream
bursts arrive at the BS at the same time independently of their distance, within
±25% of the smaller cyclic prefix (±2.33 usec or ±16 TU or sampling periods)
(A1 is regularly updated by the RNG-RSP message in sampling clock units
(TU≈1/(8/7*BW) (e.g., 145.8576 ns for 6 MHz)
(Note: a change proposed to the RNG-RSP message is to use an absolute
advance (A1) for ranging, rather a relative adjustment, to have a direct indication
of the propagation delay available at the BS. The convention is to have no
transmission advance at the CPE (A1= 0) when it is co-located with the BS.)
2.
A1 corresponds to double the BS-CPE distance: BS-CPE distance = A1*145.8*0.3/2 (m)
Submission
Slide 3
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between Base Station and CPE
(Fine Time Difference of Arrival: TDOA)
T2
A1
BS
RNG-RSP >
T1
Downstream
TTG
1.
2.
DCPE
Upstream
CPE
< RNG-REQ
BS transmits a RNG-RSP to the specific CPE and initiates its counter T1
(in TU’s) at the moment where the downstream burst leaves the BS (at
the start of the frame preamble).
The BS knows exactly the symbols on which the solicited CDMA RNGREQ will be transmitted by the CPE on the upstream since it is
registered in the US-MAP. The BS keeps this value T2 in memory (frame
symbol number allocated to the start of the RNG-REQ upstream burst).
3.
4.
The BS knows the size of the TTG in TU’s (e.g., 1439 TU for 6 MHz),
The precise residual CPE time delay measured when the CPE is colocated with the BS and the time advance indication (A1) is equal to zero
(DCPE in TU and fraction of TU down to 1 ns accuracy) is sent to the BS
(RNG-REQ, §6.10.5).
5.
Submission
A1, the advance obtained through coarse ranging, is known at the BS.
Slide 4
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
802.22 Frame structure
Reference ...
start time for
T1 counter
frame n-1
frame n
...
frame n+1
Time
10 ms
Solicited
CDMA
Ranging burst
T2
Ranging/BW request/UCS notification
60 subchannels
time buffer
Burst m
Bursts
Burst 2
Burst
Burst
Burst n
US sub-frame
RTG
TTG
Burst
DS sub-frame
Submission
Burst
time buffer
DS-MAP
Bursts
US-MAP
RNG-RSP
MAC
message
Frame Preamble
US-MAP for the
CDMA Ranging
burst
more than 7 OFDMA symbols
Burst 3
(4 or 5 symbols when scheduled)
Burst 2
Self-coexistence window
Burst 1
Burst 1
UCD
DCD
DS-MAP for the
RNG-RSP MAC
message
US-MAP
FCH
26 to 42 symbols corresponding to bandwidths from 6 MHz to 8 MHz and cyclic prefixes from 1/4 to 1/32
(smallest US burst portion on a given subchannel= 7 symbols)
Slide 5
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between Base Station and CPE
(Fine Time Difference of Arrival: TDOA)
T2
A1
BS
T1
RNG-RSP >
Downstream
5.
Submission
DCPE
Upstream
TTG
4.
Vernier-1
CPE
< RNG-REQ
Vernier-1 works on the residual phase of the preamble and/or pilot carriers in
the downstream to precisely calculate the arrival of the first multipath
relative to the synchronization time at the CPE recovered by the preamble
correlator (in TU accuracy). (Note that an advance of a few TU’s will be
provided in the CPE synchronization scheme to avoid ISI due to preechoes.)
Vernier-1 uses the information on the frequency domain equalization process
done at the CPE. The I&Q values recovered for each active subcarrier from
the preamble (and optionally pilot carriers) which will be applied at the
output of the FFT to correct the constellations in amplitude and phase for
data decoding will collectively represent the channel impulse response
referenced to the CPE receiver synchronization time.
Slide 6
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Vernier time reference
Channel impulse response
Cyclic
prefix
Useful symbol period
Reference 2k FFT sampling window
Theoretical time reference for the FFT window
where the residual phases of the vernier will be zero
Synchronized 2k FFT sampling window
Time reference for the FFT window at the CPE resulting
from the synchronization scheme using the preamble plus
the advance of a number of TU’s to avoid pre-echo leakage)
Typical vernier value (ns) (If first echo is the main signal, will be smaller if
a pre-echo exists since line-of-sight distance should rely on the first echo received.)
Submission
Slide 7
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between Base Station and CPE
(Fine Time Difference of Arrival: TDOA)
T2
A1
BS
TTG
7.
8.
9.
Submission
RNG-RSP >
T1
Downstream
Vernier-1
CPE
Upstream
< RNG-REQ
Vernier-2
The CPE responds to the RNG-RSP from the BS with a “re-range or continue”
status by sending a CDMA ranging burst during the frame specified in the
RNG-RSP message (The upstream map of the specified frame will contain a
UIUC=6 for the CDMA ranging burst for the specified symbol offset T2.)
BS receives the ranging burst and stops the T1 counter at the arrival of the
CDMA ranging burst, precisely at the time of the first sampling period
belonging to the burst. (T1 counter is in sampling periods at the BS, in TU’s)
BS acquires the I&Q values of the CDMA ranging burst carriers at the output
of the FFT and removes the CDMA signature. Off-line signal processing can
be applied onto the received 56 reference carriers to resolve the precise time
of arrival (ns) of the first multipath relative to the reference sampling time at
the BS (Vernier-2).
Slide 8
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between Base Station and CPE
(Fine Time Difference of Arrival: TDOA)
T2
A1
BS
TTG
10.
11.
12.
Submission
BLM-REQ >
T1
Downstream
Vernier-1
CPE
Upstream
< BLM-RSP
Vernier-2
The values of the frequency domain vector of Vernier-1 that were acquired
during the downstream burst (preamble and optionally pilots carriers) will be
queried later by the BS through the BLM-REQ message.
The CPE will send these values (1680 I&Q values coded in 8 bits) to the BS
when time allows.
Once the Vernier-1 vector is acquired by the BS, signal processing can be
performed off-line. The precise delay (ns) of the first channel echo relative
to the synchronization reference at the CPE can be extracted.
Slide 9
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between Base Station and CPE
(Fine Time Difference of Arrival: TDOA)
T2
BS
TTG
13.
14.
Submission
Downstream
A1
T1
Upstream
Vernier-1
CPE
Vernier-2
BS knows:
TTG in TU’s (e.g., 1439 TU for 6 MHz),
T2 in symbols from the scheduling of the ranging burst: n* ((1+CP)*2048 TU),
DCPE representing the precise maximum CPE delay measured when the CPE is
co-located with the BS in TU and fraction of TU to an accuracy of 1 ns.
T1 from the stopped counter in TU,
V1 from the processing of the acquired Vernier-1 vector in ns,
V2 from the processing of the acquired Vernier-2 vector in ns.
All the information necessary to calculate the propagation time between BS and
CPE is known down to a nanosecond accuracy:
Ptime = T1 - (T2 + TTG) - (fraction of DCPE)+V1 + V2
(ns)
Distance = c * Ptime/2 (m)
Slide 10
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Validation of the Vernier concept
I
Carrier phase reversal
based on the LTS coding
...
Frequency
Convolution with channel
impulse response
LTS
I
Q
I
Q
I
Q
Q
...
IDFT
τ
Q
1
Sync
advance
Time
I
Time
Q
I
IDFT
Frequency
Time
I
Q
I
Q
...
Cyclic prefix
IQ Vector
DFT
I
Q
Q
I
2048 samples
LTS distorted
by channel
I
Q
Q
Real
I
Frequency
Dirac distorted
by channel
g time
Samplin
Ima
gin
ar
y
Complex channel impulse response relative
to the receiver synchronization time
Submission
Slide 11
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Validation of the Vernier concept
Real
Channel impulse response
relative to the sampling time
g times
Samplin
Ima
gin
a ry
I
2048 I&Q samples at sampling
period (i.e., every 145.86 ns)
Q
1
Real
I
0
Q
Complex
correlation
-1
1
0
Imaginary
1
Precise time sample
High resolution band
limited impulse response
(e.g., every 0.81 ns)
I
Q
τ
2
τ
τ
3
1
Channel impulse response
relative to the sampling time
Submission
Slide 12
2048 x 180 I&Q samples
at every 0.81 ns
Amplitude1
Amplitude2
Amplitude3
Amplitude4
etc...
Delay1
Delay2
Delay3
Delay4
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Amplitude
802.22 OFDM Subcarrier Set
-840
Submission
0 +1
-1
Subcarrier index
Slide 13
+840
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimulus
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 14
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimulus
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 15
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimulus
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 16
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimulus
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 17
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimulus
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 18
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimulus
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 19
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimuli
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 20
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
Stimuli
0.5
10000
9000
0
8000
-0.5
Imaginary
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
145.8 ns
Submission
Slide 21
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
Real
0.5
0
-0.5
-1
1
0.5
10000
9000
0
8000
-0.5
Imaginary
Submission
7000
-1
6000
Precise time sample =145.86/180= 0.81 ns
Slide 22
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
0.8
0.6
0.4
Real
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
1
0
-1
Imaginary
6000
6500
7000
7500
8000
8500
9000
9500
10000
Precise time sample =145.86/180= 0.81 ns
Submission
Slide 23
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
0.8
0.6
0.4
Real
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
6000
Submission
6500
7000
7500
8000
8500
9000
9500
Precise time sample =145.86/180= 0.81 ns
Slide 24
10000
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
LTS prototype function
1
0.8
0.6
0.4
Real
0.2
0
-0.2
-0.4
-0.6
Stimulus
-0.8
-1
6000
6500
7000
7500
8000
8500
9000
9500
Precise time sample =145.86/180= 0.81 ns
10000
145.8 ns
Submission
Slide 25
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Prototype function construction
1
0.8
0.6
0.4
Real
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
1
0.5
0
Imaginary
-0.5
-1
6000
6500
7000
7500
8000
8500
9000
9500
10000
Precise time sample =145.86/180= 0.81 ns
Submission
Slide 26
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Validation of the Vernier concept
Real
Channel impulse response
relative to the sampling time
g times
Samplin
Ima
gin
a ry
I
2048 I&Q samples at sampling
period (i.e., every 145.86 ns)
Q
1
Real
I
0
Q
Complex
correlation
-1
1
0
Imaginary
1
Precise time sample
High resolution band
limited impulse response
(e.g., every 0.81 ns)
I
Q
τ
2
τ
τ
3
1
Channel impulse response
relative to the sampling time
Submission
Slide 27
2048 x 180 I&Q samples
at every 0.81 ns
Amplitude1
Amplitude2
Amplitude3
Amplitude4
etc...
Delay1
Delay2
Delay3
Delay4
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Channel B
Submission
Slide 28
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Advanced and delayed responses
Submission
Slide 29
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical LTS generated multipath response
1
Real
Abs
0.8
0.6
0.4
Amplitude
0.2
SNR= 0 dB
0
-0.2
-0.4
-0.6
-0.8
-1
Submission
20
40
60
80
100
120
140
Time samples (1 sample = 145.86 ns)
Slide 30
160
180
200
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical LTS generated multipath response
LTS multipath response
1
Real
0.5
0
-0.5
-1
1
0.5
200
150
0
100
-0.5
Imaginary
Submission
50
-1
Time samples (1 sample = 145.86 ns)
Slide 31
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical LTS generated multipath response
1
Real
Abs
0.8
0.6
0.4
Amplitude
0.2
SNR= 0 dB
0
-0.2
-0.4
-0.6
-0.8
-1
Submission
20
40
60
80
100
120
140
Time samples (1 sample = 145.86 ns)
Slide 32
160
180
200
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical LTS generated multipath response
1
Real
Abs
0.8
0.6
0.4
Amplitude
0.2
SNR= 0 dB
0
-0.2
-0.4
-0.6
-0.8
-1
5
Submission
10
15
20
25
30
35
40
45
Time samples (1 sample = 145.86 ns)
Slide 33
50
55
60
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Validation of the Vernier concept
Real
Channel impulse response
relative to the sampling time
g times
Samplin
Ima
gin
a ry
I
2048 I&Q samples at sampling
period (i.e., every 145.86 ns)
Q
1
Real
I
0
Q
Complex
correlation
-1
1
0
Imaginary
1
Precise time sample
High resolution band
limited impulse response
(e.g., every 0.81 ns)
I
Q
τ
2
τ
τ
3
1
Channel impulse response
relative to the sampling time
Submission
Slide 34
2048 x 180 I&Q samples
at every 0.81 ns
Amplitude1
Amplitude2
Amplitude3
Amplitude4
etc...
Delay1
Delay2
Delay3
Delay4
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical correlation output waveform
1
Real
Samples
0.8
0.6
Correlation Output Amplitude
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
0.5
Submission
1
1.5
2
2.5
Precise time samples (1 sample = 145.86 ns)
Slide 35
3
3.5
x 10
4
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical correlation output waveform
1
Real
Samples
0.8
0.6
Corrrelation Output Amplitude
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Precise time samples (1 sample = 0.81 ns)
Submission
Slide 36
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical correlation output waveform
Correlation Response
0.45
Imag
Real
Samples
0.4
Real and Imaginary Amplitudes
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
7500
Submission
8000
8500
9000
9500
Precise time samples (1 sample = 0.81 ns)
Slide 37
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical correlation output waveform
Correlation Response
0.395
Imag
Real
Samples
0.3948
Real and Imaginary Amplitudes
0.3946
0.3944
0.3942
0.394
0.3938
0.3936
0.3934
0.3932
8763
Submission
8764
8765
8766
8767
8768
8769
8770
Precise time samples (1 sample = 0.81 ns)
Slide 38
8771
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Multipath results summary
SNR (dB) =
(dB)
Micro-shift (1/10 sampling period)
(ns)
Relative
Nominal
Path #
Samples Delay (us)
power (dB) delay (us)
2
0
0
0
5.104
1
-6
-3
-21
2.042
3
-7
2
14
7.146
5
-16
7
48
12.104
6
-20
11
75
16.042
Wrong echoes:
4
-22
4
27
9.042
SNR (dB) =
(dB)
Micro-shift (1/10 sampling period)
(ns)
Relative
Nominal
Path #
Samples Delay (us)
power (dB) delay (us)
2
0
0
0
5.104
1
-6
-3
-21
2.042
3
-7
2
14
7.146
5
-16
7
48
12.104
6
-20
11
75
16.042
Wrong echoes:
4
-22
4
27
9.042
SNR (dB) =
(dB)
Micro-shift (1/10 sampling period)
(ns)
Relative
Nominal
Path #
Samples Delay (us)
power (dB) delay (us)
2
0
0
0
5.104
1
-6
-3
-21
2.042
3
-7
2
14
7.146
5
-16
7
48
12.104
6
-20
11
75
16.042
Wrong echoes:
4
-22
4
27
9.042
Submission
60
-43.758
20
-43.758
10
-43.758
6
-43.758
3
-43.758
0
-43.758
-3
-43.758
-6
-43.758
-10
-43.758
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
0.000
-0.810
-0.810
0.810
-1.620
1
-4.861
0.810
-0.810
0.000
1.620
-1.620
1
-5.671
0.000
-1.620
-0.810
1.620
-2.431
0.810
-0.810
0.000
-1.620
2.431
-11.343
-10.532
0.000
-1.620
0.000
-0.810
-8.102
1
-4.051
0.000
0.810
0.000
9.722
-4.051
2
-27.546
0.810
-3.241
-0.810
-5.671
4.861
4
-17.014
-1.620
3.241
-4.051
2.431
22.685
7
9.722
3.241
-8.912
2.431
8.912
-23.495
8
1382.176
60
0
20
0
10
0
6
0
3
0
0
0
-3
0
-6
0
-10
0
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
0.810
-0.810
-0.810
0.810
-1.620
1
-4.861
0.810
-0.810
0.000
1.620
-3.241
1
-3.241
0.810
-0.810
-0.810
1.620
0.000
0.810
0.000
-0.810
3.241
-3.241
0.810
-2.431
0.000
-3.241
-1.620
-0.810
-8.102
0.000
-3.241
-1.620
-3.241
8.912
1
1.620
-4.051
-0.810
2.431
2.431
-3.241
-29.977
1
-9547.222
2.431
-2.431
4.861
-181.481
8.102
7
9583.681
-0.810
4.051
7.292
20.255
-330.556
8
-5045.023
60
43.758
20
43.758
10
43.758
6
43.758
3
43.758
0
43.758
-3
43.758
-6
43.758
-10
43.758
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
0.810
-0.810
0.000
0.810
-0.810
1
-4.861
0.000
-0.810
-0.810
0.810
-2.431
0.810
0.000
-1.620
2.431
3.241
3
-11.343
0.000
-0.810
-2.431
1.620
-0.810
0.000
-0.810
0.000
2.431
-4.861
7
-12.153
0.000
1.620
1.620
8.102
-3.241
1.620
-1.620
-7.292
-4.051
0.000
-7198.495
-9765.972
0.000
0.810
3.241
-480.440
-0.810
8
3064.931
0.810
1.620
0.810
-20.255
0.000
5
3.241
-5.671
Slide 39
1.620
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Typical correlation output waveform
1
Real
Samples
0.8
0.6
Wrong
echo
Corrrelation Output Amplitude
0.4
0.2
0
-0.2
-0.4
-0.6
-0.8
-1
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Precise time samples (1 sample = 0.81 ns)
Submission
Slide 40
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Multipath results summary (cont’d)
SNR (dB) =
(dB)
Micro-shift (1/10 sampling period)
(ns)
Relative
Nominal
Path #
Samples Delay (us)
power (dB) delay (us)
2
0
0
0
5.104
1
-6
-3
-21
2.042
3
-7
2
14
7.146
5
-16
7
48
12.104
6
-20
11
75
16.042
Wrong echoes:
4
-22
4
27
9.042
SNR (dB) =
(dB)
Micro-shift (1/10 sampling period)
(ns)
Relative
Nominal
Path #
Samples Delay (us)
power (dB) delay (us)
2
0
0
0
5.104
1
-6
-3
-21
2.042
3
-7
2
14
7.146
5
-16
7
48
12.104
6
-20
11
75
16.042
Wrong echoes:
4
-22
4
27
9.042
SNR (dB) =
(dB)
Micro-shift (1/10 sampling period)
(ns)
Relative
Nominal
Path #
Samples Delay (us)
power (dB) delay (us)
2
0
0
0
5.104
1
-6
-3
-21
2.042
3
-7
2
14
7.146
5
-16
7
48
12.104
6
-20
11
75
16.042
Wrong echoes:
4
-22
4
27
9.042
Submission
60
-72.93
20
-72.93
10
-72.93
6
-72.93
3
-72.93
0
-72.93
-3
-72.93
-6
-72.93
-10
-72.93
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
0.810
-0.810
-0.810
0.810
-1.620
1
-4.861
0.000
-0.810
-0.810
0.810
-1.620
1
-4.861
0.000
-0.810
0.000
-1.620
-4.051
2
-0.810
0.000
-0.810
-1.620
0.810
0.810
0.810
-1.620
-0.810
-1.620
-4.051
2
15.394
1.620
-0.810
2.431
-5.671
-2.431
8
-682.986
2.431
0.000
0.810
36.458
-8.912
-8.912
0.810
-1.620
0.000
-1.620
-4.051
5
-20.255
18035.532
1.620
5.671
-6.481
6.481
-1.620
9
-638.426
60
0
20
0
10
0
6
0
3
0
0
0
-3
0
-6
0
-10
0
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
0.810
-0.810
-0.810
0.810
-1.620
1
-4.861
0.810
-0.810
0.000
1.620
-3.241
1
-3.241
0.810
-0.810
-0.810
1.620
0.000
0.810
0.000
-0.810
3.241
-3.241
0.810
-2.431
0.000
-3.241
-1.620
-0.810
-8.102
0.000
-3.241
-1.620
-3.241
8.912
1
1.620
-4.051
-0.810
2.431
2.431
-3.241
-29.977
1
-9547.222
2.431
-2.431
4.861
-181.481
8.102
7
9583.681
-0.810
4.051
7.292
20.255
-330.556
8
-5045.023
60
72.93
20
72.93
10
72.93
6
72.93
3
72.93
0
72.93
-3
72.93
-6
72.93
-10
72.93
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
Delta (ns)
0.000
-0.810
-0.810
0.810
-0.810
1
-4.861
0.000
-0.810
0.000
0.810
0.000
1
-4.051
0.000
-0.810
-0.810
1.620
-8.102
1
-3.241
1.620
-2.431
0.000
2.431
-2.431
2
12.963
0.810
-1.620
-0.810
-1.620
-5.671
2
-0.810
1.620
-4.051
0.000
3.241
-2.431
5
-5.671
0.810
0.810
-2.431
-0.810
4.861
2
1088.079
0.000
0.000
3.241
-12.153
21.065
5
448.843
0.000
1.620
-1.620
-12.963
8708.681
Slide 41
-6167.940
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Lab measurement setup
MATLAB
Signal generation
and modulation
PNsequence
generator
LTS
sequence
construction
2048-point
ifft
512-point
Cyclic
Prefix
addition
Ethernet
interface
Agilent
Reference
Oscillator
Agilent
ESG4438C
signal generator
UHF TV
channel
Calibrated
multipath
and noise
HP 11759C
Channel
Simulator
MATLAB
ifft
LTS
Signature
removal
fft
Cyclic
Prefix
Removal
Correlator
Sampling
frequency
converter
Ethernet
interface
Agilent
N9020A MXA
Vector Signal
Analyzer
I&Q
Channel impulse
response estimate
Submission
Slide 42
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Vector Amplitude (ABS)
LTS-H I&Q Vector for analysis
Samples
Submission
Slide 43
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Precise channel impulse after correlation
with prototype function
1
Correlation output
Impulse response samples
0.8
4.950231 usec sync advance
0.6
Correlation response
0.4
2.997847 usec
0.2
0
-0.2
Error= 2.15 ns
-0.4
enlever
Pre-echo= 3 usec
-0.6
-0.8
-1
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Precise time samples (1 sample= 0.81 ns)
Submission
Slide 44
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Subcarrier patterns for geolocation
Downstream:
• Frame preamble
Long training sequence: 840 subcarriers (one every two)
Time interval: 149.4 usec (Can easily absord all multipaths)
Upstream:
• CDMA Ranging burst
Burst on 2 sub-channels: 56 subcarriers (one every 30)
Time interval: 9.96 usec (Cannot absord all multipaths)
Burst on 2 sub-channels: 56 subcarriers unevenly spread
(one every 10)
Time interval: 29.87 usec (Can absord all multipaths)
Reduced time localization of the Prototype function
Need a search for the best spread for best localization.
Submission
Slide 45
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
56-carrier prototype function localization
0
Poor selection
-10
Relative Amplitude (dB)
-20
-30
-40
-50
-60
Submission
50
100
150
200
250
300
350
Time samples (1 sample = 58.3 ns)
Slide 46
400
450
500
29.87 usec
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
56-carrier prototype function localization
Better selection
(1 sample = 58.3 ns)
Submission
Slide 47
29.87 usec
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between CPEs
(Fine Time Difference of Arrival: TDOA)
T2
BS
TTG
Downstream
A1
DCPE
T1
Vernier-2
DCPE
2.
3.
Submission
CBP burst
Upstream
Vernier-1
1.
Vernier-1
CPE
2
CPE
1
Vernier-3
BS signals the presence of a SCW in the upstream burst of the current frame
using its upstream map (§6.10.4.1). It signals which CPEs will be in active
mode (UIUC= 0) to transmit the CBP burst and which CPEs will be in passive
mode (UIUC= 1, sync mode= 0) to listen and capture the CBP burst keeping
their current synchronization (§6.10.4.1, comment #351).
BS sends a RNG-RSP message to both active and passive CPEs involved in
the CPE-to-CPE ranging (could also be done in previous or following frames).
Upon arrival of the RNG-RSP request, CPEs will start their vernier-1 as
described before (slides #4, 6 and 8) and capture the I&Q values of the
reference carriers from the current frame preamble (and optionally pilot
carriers) and respond with the RNG-REQ bursts in the slots allocated.
Slide 48
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between CPEs
(Fine Time Difference of Arrival: TDOA)
T2
BS
TTG
Downstream
A1
DCPE
T1
Vernier-2
DCPE
5.
6.
7.
Submission
CBP burst
Upstream
Vernier-1
4.
Vernier-1
CPE
2
CPE
1
Vernier-3
CPE-1 in active mode will then initiate the CBP burst transmission containing
its identification (§6.8.1.2.1.7) at the start of the second symbol of the SCW
CPE-2 in passive mode and sync mode 0 will capture the CBP burst and start
vernier-3 to acquire the I&Q values of the reference carriers from the CBP
preamble (and optionally pilot carriers) to help recover the precise time at
which the CBP burst has arrived at the CPE-2.
The BS will query the CPE-1 for its I&Q vectors acquired by its vernier-1 to
carry out the precise BS-CPE ranging process off-line.
The BS will query the CPE-2 for its I&Q vectors acquired by its vernier-1 to
carry out the precise BS-CPE ranging process off-line.
Slide 49
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
Propagation time between CPEs
(Fine Time Difference of Arrival: TDOA)
T2
BS
TTG
Downstream
A1
DCPE
T1
Vernier-2
DCPE
9.
10.
Submission
CBP burst
Upstream
Vernier-1
8.
Vernier-1
CPE
2
CPE
1
Vernier-3
The BS will then query the CPE-2 for its I&Q vector acquired by vernier-3.
The propagation paths between the CPEs can now be calculated off-line.
The BS, or a terrestrial geolocation server, can then use the channel inpulse
responses acquired in item 6, 7 and 8 to validate the line-of-sight propagation
distances on each of the three paths despite possible multipath between the BS
and the CPEs involved in the ranging process (e.g., identify the most reliable
first echo and discarding calculations based on those that do not have a clear
first path that would closely correspond to a line-of-sight condition).
The BS, or a terrestrial geolocation server, can then carry out triangulation
based on reliable propagation paths to geolocate the CPEs using known
waypoints (BS and some specific CPEs).
Slide 50
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
References
1.
2.
3.
4.
5.
6.
7.
IEEE P802.22™/ DRAFTv2.0 Draft Standard for Wireless Regional Area Networks
Part 22: Cognitive Wireless RAN Medium Access Control (MAC) and Physical Layer
(PHY) specifications: Policies and procedures for operation in the TV Bands, May
2009
22-06-0206-00-0000-ranging-with-ofdm-systems.ppt
Krizman, K.J.; Biedka, T.E.; Rappaport, T.S.; ”Wireless position location:
fundamentals, implementation strategies, and sources of error”, Vehicular Technology
Conference, 1997 IEEE 47th Volume 2, 4-7 May 1997 Page(s):919 - 923 vol.2, Digital
Object Identifier 10.1109/VETEC.1997.600463
22-06-0141-00-0000_Locator_Presentation 802_22 July2006.pdf
Gustafsson, F.; Gunnarsson, F.; "Mobile positioning using wireless networks:
possibilities and fundamental limitations based on available wireless network
measurements", Signal Processing Magazine, IEEE, Volume 22, Issue 4, July 2005
Page(s):41 – 53
Reed, J.H.; Krizman, K.J.; Woerner, B.D.; Rappaport, T.S.; “An overview of the
challenges and progress in meeting the E-911 requirement for location service”,
Communications Magazine, IEEE Volume 36, Issue 4, April 1998 Page(s):30 - 37
Hepsaydir, E.; ‘Mobile positioning in CDMA cellular networks”, Vehicular
Technology Conference, 1999. VTC 1999 - Fall. IEEE VTS 50th, Volume 2, 19-22
Sept. 1999 Page(s):795 - 799 vol.2
Submission
Slide 51
Gerald Chouinard, CRC
March 2010
doc.: IEEE 802.22-10/0054r1
References (cont’d)
8.
9.
10.
11.
12.
13.
Schmidl, T.M.; Cox, D.C;”Robust frequency and timing synchronization for OFDM”,
Communications, IEEE Transactions on Volume 45, Issue 12, Dec. 1997 Page(s):1613
Minn, H.; Zeng, M.; Bhargava, V.K.; "On timing offset estimation for OFDM
systems", Communications Letters, IEEE Volume 4, Issue 7, July 2000 Page(s):242 –
244
Morelli, M.; Mengali, U.; "An improved frequency offset estimator for OFDM
applications", Communication Theory Mini-Conference, 1999, 6-10 June 1999
Page(s):106 - 109
Mensing, C.; Plass, S.; Dammann, A.; ”Synchronization Algorithms for Positioning
with OFDM Communications Signals”, Positioning, Navigation and Communication,
2007. WPNC '07,. 4th Workshop 22-22 March 2007. Page(s):205 – 210
Fredrick S. Solheim1, Jothiram Vivekanandan1, Randolph H. Ware, Christian Rocken;
"Propagation Delays Induced in GPS Signals by Dry Air, Water Vapor, Hydrometeors
and Other Particulates", Journal of Geophysical Research,104, 9663-9670, 1999
http://www.kowoma.de/en/gps/errors.htm
Submission
Slide 52
Gerald Chouinard, CRC