esa project 1300008360 uwb radio for cable replacement in satellites
DESCRIPTION
ESA project 1300008360 UWB radio for cable replacement in Satellites. Technical Note 1.1 “ Hardware description, environment and test plan ”. Introduction. Feasibility study for use of UWB radio for cable-replacements in intra-satellite communication. Project contains 3 activities: - PowerPoint PPT PresentationTRANSCRIPT
© IMEC 2011
ESA PROJECT 1300008360UWB RADIO FOR CABLE REPLACEMENT IN SATELLITESTECHNICAL NOTE 1.1 “HARDWARE DESCRIPTION, ENVIRONMENT AND TEST PLAN”
© IMEC 2011
INTRODUCTIONFeasibility study for use of UWB radio for cable-replacements in intra-satellite communication.
Project contains 3 activities:1. Hardware description, environment and test plan
Outcome: (TN1.1 = document)2. Measurement campaign
Outcome: (TN1.2a=Zip-file)3. Test report and analyses
Outcome: (TN1.2= > update of TN1.1) 2 versions: with and without confidential
informationThis presentation reports on TN1.2
2
© IMEC 2011 3
OUTLINE OF THE DOCUMENT
1 Introduction ................................................................................. 1
2 IEEE802.15.4a UWB air interface........................................... 3
3 Top-level description of IMEC UWB transceivers..... ......... 11
4 Methodology................................................................................ 27
5 Venus express Mock-up description ......................................29
6 Channel Measurements and Modelling ................................. 33
7 Simulation framework and results ......................................... 67
8 Conclusions and recommendations....................................... 73
9 Bibliography................................................................................... 75
© IMEC 2011 4
802.15.4A STANDARD
▸ 3 modes => mean Pulse repetition freq- 15.6 MHz- 3.9 MHz- 62.4 MHz
▸ 4 submodes => PHY bitrate- 27Mb/s- 6.8 Mb/s- 850 kb/s- 110 kb/s
▸ Off standard modes allow for other data rates as well- Use of ASIP/ASIC combination makes TX/RX
flexible! - Unique to IMEC technology
© IMEC 2011 5
METHODOLOGY
© IMEC 2011 6
ENVIRONMENT & MEASUREMENTS Parameters:▸ Satellite:
- Highly reflective environment- Significant reflection up to one microseconds
▸ BW:- 1-11 GHz (covers much communication
standards)- Time resolution => 100 picoseconds
▸ #FreqPoint > 1microsec/100picosec(=10k)▸ Nearest power of 2 => 16384 (DFT =>
FFT )▸ FreqStep = 610 kHz.
Result: H[f] => H(f)
Channel measurements showed the validity of these assumption
© IMEC 2011 7
FREQ TO DELAY
Freq domain DFT Delay domain H[f,t] (=S21) <=> H[tau,t]Only valid if channel is constant
• True if doors are closed• Not guaranteed if doors are opened
© IMEC 2011 8
MEASUREMENT REQUIREMENT
Measurement of H(f,t) takes approx 2 sec!Nothing may move more than 0.5cm over 2 seconds in relevant area!Relevant area = area relevant paths act. Do relevant paths exit & return from Mock-Up?
True if doors are closed False if doors are opened!
© IMEC 2011 9
MEASUREMENT SETUP
=keyhole
Type amount
remark
Closed doors 36 6 intra cavity, 28 inter cavity, pathOpen doors 61 41*(5->6) + 20*(2->5)Antenna position
21 8*(5->5) + 5*(6->5) + 7*(2->5)
© IMEC 2011
CHANNEL MEASUREMENT RESULTSPATH LOSS
3 4 5 6 7 8 9 10-70
-60
-50
-40
-30
-20
-10
0
Frequency [GHz]
Cha
nnel
Gai
n [d
B]
UWB [500 MHz]WLAN [20 MHz]Raw Data [610kHz]
1/f2
Channel gain as a function of carrier frequency with a sliding window.
© IMEC 2011
0 0.5 1 1.5 2 2.5 3-60
-55
-50
-45
-40
-35
-30
-25
-20
#Keyholes
Cha
nnel
Los
s[dB
]
CHANNEL MEASUREMENT RESULTSPATH LOSS
Cavity 1 2 3 4 5 6
Path loss(dB)
-26 -25 -27 -25 -27 -27
Cavity Rx in 1
Rx in 2
Rx in 3
Rx in 4
Rx in 5
Rx in 6
Tx in 1 X -34 -41 -49 -50 -58
Tx in 2 -34 X -47 -42 -56 -53
Tx in 3 -41 -47 X -54 -41 -52
Tx in 4 -48 -41 -54 X -52 -42
Tx in 5 -50 -56 -41 -52 X -39
Tx in 6 -56 -52 -52 -42 -39 X
Channel gain as a function of the number of keyholes
Path losses (units in dB) for inter cavity measurements.
Large scale path loss
© IMEC 2011
CHANNEL MEASUREMENT RESULTSIMPACT OF ANTENNA POSITION
3 4 5 6 7 8 9 10-100
-80
-60
-40
-20
0
Frequency [GHz]
Cha
nnel
Gai
n [d
B]
Measurement 1Measurement 2Measurement 3Measurement 4Measurement 5Measurement 6Measurement 7Measurement 8
Intra cavity measurements VNA channel 1 (Tx) and VNA channel 2 (Rx) in cavity 5 with 8 different antenna position configurations.
LOS, Close proximity
NLOS,Antennae at oppositeKey holes
© IMEC 2011
CHANNEL MEASUREMENT RESULTSIMPACT OF OPEN DOORS
3 4 5 6 7 8 9 10-75
-70
-65
-60
-55
-50
000000000001000010000100001000010000100000000101001001001100010010100001100100101000001101100101101001101100101101111111
Effect of opening and closing of doors on the link-budget for inter cavity measurements VNA channel 1 (Tx) in cavity 2 and VNA channel 2 (Rx) in cavity 5 with many different door configuration. Doors 2 and 5 have the biggest impact.
• The opening of doors may lead to a channel gain loss up to 18 dB
© IMEC 2011
CHANNEL MEASUREMENT RESULTSDELAY DOMAIN
0 200 400 600 800 1000 1200 1400 1600-160
-140
-120
-100
-80
-60
-40
time [ns]
S21
[dB
] Ban
dwid
th [1
0 G
Hz]
Real MeasurementSynthetic data
Real measured data for inter cavity measurement of cavity 1 to cavity 3, and synthetically generated data with the aid of two exponential functions and a noise floor describing the envelope.
Cavity 1 2 3 4 5 6
RMS delay
spread (ns)
40.7 37.5 34.6 16.0 35.8 34.9
Cavity Rx in 1 Rx in 2 Rx in 3 Rx in 4 Rx in 5 Rx in 6
Tx in 1 X 57.2 59.3 67.2 77.2 118.6
Tx in 2 56.3 X 73.2 46.6 109.5 80.0
Tx in 3 59.7 74.5 X 81.8 53.8 82.1
Tx in 4 69.0 47.5 82.6 X 77.9 44.6
Tx in 5 77.4 109.4 55.6 78.0 X 54.1
Tx in 6 110.6 75.8 81.4 44.1 52.3 X
RMS delay spread (units in ns) for inter cavity measurements.
© IMEC 2011
CHANNEL MEASUREMENT RESULTSDELAY DOMAIN
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.160
2
4
6
8
10
12
14
16
Amplitude [V]
Den
sity
Raw dataRicean fitRayleigh fit
Histogram of received signal voltage from 4 - 5 GHz and the estimated Ricean and Rayleigh distribution for both VNA channel 1 (Tx) and VNA channel 2 (Rx) in cavity 2.
Cavity 1 2 3 4 5 6
-17 -16 -14 -12 -18 -20
Cavity Rx in 1 Rx in 2 Rx in 3 Rx in 4 Rx in 5 Rx in 6
Tx in 1 X -23 -22 -22 -22 -24
Tx in 2 -22 X -24 -21 -24 -24
Tx in 3 -23 -22 X -23 -22 -24
Tx in 4 -22 -22 -22 X -22 -22
Tx in 5 -23 -24 -22 -23 X -23
Tx in 6 -24 -22 -24 -21 -23 X
Ricean factors (units in dB) for inter cavity measurements.
Small scale fading is Rayleigh distributed
© IMEC 2011
CHANNEL MEASUREMENT RESULTSMINIMUM AND MAXIMUM PATH LOSSES
3 4 5 6 7 8 9 10-70
-60
-50
-40
-30
-20
-10
0
Frequency [GHz]
Cha
nnel
Gai
n [d
B]
UWB [500 MHz]WLAN [20 MHz]Raw Data [610kHz]
Intra cavity measurement in cavity 3 with 2σ confidence intervals over 1GHz windows. Solid line, UWB, striped line, WLAN, dotted line, Raw Data.
0 0.5 1 1.5 2 2.5 30
2
4
6
8
10
12
14
16
18
20
#Keyholes2
in
terv
al c
orre
spon
ding
to C
hann
el G
ain
[dB
]
UWB [500 MHz]WLAN [20 MHz]
The 2σ confidence intervals corresponding to the channel gain for the seven 1GHz windows for both intra and inter cavity measurements as a function of the number of 12 x 12 cm keyholes, i.e. hops.
• 2σ 5 dB mean power gain variation due to small scale fading. • Mean power mainly depends on cavity not on position
© IMEC 2011 17
SIMULATION RESULTS
Flexible 802.15.4a simulation environment▸ Matlab
Complex-valued BB equiv. system model
non-coherent reception
Flexible PSDUsize
Added CRC16
Noise equal to measuredRXFE noise-figure
Iff CRC passes
Flexible Data rate/Modulation scheme
© IMEC 2011 18
0 0.5 1 1.5 2 2.5 3 3.5 4
x 105
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1x 10
-3
Time
Ampl
itude
SHR preamble PHY header and Datapreamble
Preamble tracking and SFD Detection Payload decodingFine acquizition
SFD
SIMULATION RESULTS PER as measure for performance:▸ most honest but worse-case performance
criteria
Fine acquisition SFD
detection
PHY HDRdecoding
CRC check
Only successful reception if everything goes well.
© IMEC 2011 19
PER WITH CLOSED DOORS
Many things can go wrong, but it does not;-) Reasons: ▸ Low average pathloss,
▸ highly reflective environment
▸ Keyholes are larger enough
▸ Hardly no small-scale fading▸ UWB is able to resolve
many multipath components
© IMEC 2011 20
PER WITH OPEN DOORS Many things can go wrong, and here it does;-( With 1 hop everything is fine 3 hops is too much Reason: • Energy leaks into environment,
lowering RX powerBut:• ‘only’ 10 dB improvement needed• Link improvement are possible
• ↑TX power, ↓noise figure• Tailor BB processing• Network layer
© IMEC 2011
CONCLUSION
The satellite’s radio channel is a high reflective/multipath-rich environment in which radio signal are able to propagate from one cavity to the next.
The large scale path loss of the channel for a frequency range of 3-10 GHz varies between -25dB (intra-cavity) to-58dB (cavity 1 to cavity 6) with closed doors.
The RMS delay spread varies between 40.7 ns (intra-cavity) and 118.6 ns (cavity 1 to cavity 6).
The small-scale-fading for narrowband systems is Rayleigh distributed even in LOS conditions. An example of such a narrowband system is 802.15.4. To obtain robust communication links, some form of diversity will be needed.
UWB systems experience a mean power gain variation of at most 5 dB due to small-scale-fading, due to its inherent frequency diversity.
The mean power gain of the channel depends mainly on the cavities of TX and RX, i.e. the exact position of the TX/RX within these cavities has little impact.
© IMEC 2011 22
CONCLUSION
Opening of the satellite doors may lead to a decrease of the channel gain in the order of 15-18 dB for intra cavity channel and 10-13 dBs for inter cavity channels; depending on the contribution of the door as reflective object to the overall channel transfer function.
The most difficult channels are measured from cavity 1 to cavity 6 with open doors at high frequencies (6-10 GHz), where a mean power gain of -70 dB was recorded.
Imec’s current 802.15.4a-compliantUWB radio technology is able to provide for robust communication links at 600 kb/s netto data rate without packet loss:▸ from each cavity to every other cavity, if the doors are closed.▸ Very likely from each cavity to adjacent cavities with open doors.
Imec’s current 802.15.4a-compliant UWB radio technology is not able to provide for robust communication links from each cavity to every other cavity at 600 kb/s netto data rate without packet loss, if all doors are open and the cavity distance (hops) is larger than 1.
© IMEC 2011
CHANNEL MEASUREMENT RESULTS
The satellite’s radio channel is a high reflective/multipath-rich environment in which radio signal are able to propagate from one cavity to the next.
The large scale path loss of the channel for a frequency range of 3-10 GHz varies between -25dB (intra-cavity) to-58dB (cavity 1 to cavity 6) with closed doors.
The RMS delay spread varies between 40.7 ns (intra-cavity) and 118.6 ns (cavity 1 to cavity 6).
The small-scale-fading for narrowband systems is Rayleigh distributed even in LOS conditions. An example of such a narrowband system is 802.15.4. To obtain robust communication links, some form of diversity will be needed.
UWB systems experience a mean power gain variation of at most 5 dB due to small-scale-fading, due to its inherent frequency diversity.
The mean power gain of the channel depends mainly on the cavities of TX and RX, i.e. the exact position of the TX/RX within these cavities has little impact.
Opening of the satellite doors may lead to a decrease of the channel gain in the order of 15-18 dB for intra cavity channel and 10-13 dBs for inter cavity channels; depending on the contribution of the door as reflective object to the overall channel transfer function.
© IMEC 2011 24
RECOMMENDATIONS
EMC▸ Study ESA’s EMC requirement wrt FCC part
15 regulation for intentional radiators▸ EMC center Eindhoven could play a role!
© IMEC 2011 25
RECOMMENDATIONS
Centralized network topology▸ Only intra-cavity communication,▸ Inter cavity communication via wired bus
system▸ Increased system capacity▸ Beneficial if one of few data-sink can be
identified Ad-hoc network topology▸ Each sensor/tag may communicate to any
other sensor/tag▸ More complicated MAC (assuming no fixed
addressing)