© 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)