Co-existence of MP- MP and PMP Systems

BFWAtg(00)30

Co-existence of MP- MP and PMP Systems

Philip Whitehead

Radiant Networks PLC

BFWAtg(00)30

Coexistence

• Definition:– The ability of two (or more) systems to operate in the

presence of mutual interference with acceptable degradation of performance

• Two main scenarios– Systems operating on the same channels in adjacent or

nearby areas.– Systems operating in overlapping areas and using adjacent

or near- adjacent channels.

BFWAtg(00)30

• No base stations• Short paths• All antennas are directional• Low antenna heights• Low transmitter power• Very good frequency re-use• Detect and avoid interference

Improved co-existence

General Characteristics of Mesh Systems

BFWAtg(00)30

Main conclusions from the study

• Mesh and PMP systems can easily co-exist• Guard bands can be reduced or even zero• Co-channel systems can be very close together

(closer than PMP – PMP)• Rain fading has negligible impact

BFWAtg(00)30

Methodology

• Simulation of (random) mesh with large number of subscribers

• 20GHz - 43.5GHz considered – results presented for 28GHz band

• Multiple interferers • 3-D geometry • Effects of buildings (LOS probability calculated)• Atmospheric attenuation and rain fading according to

ITU-R

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Geometry

CL

mesh X-dim

mes

h to

t Y

-di

m

Base Station Receivercell radius

90

Meshm

esh

boun

dar

y

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3D Geometry

Mesh rx

hub

sub

Mesh tx

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Link Length Distribution

Length distribution of mesh links

0.0%

5.0%

10.0%

15.0%

20.0%

1 2 3 4 5 6 7 8 9 10

Max range (100s of m)

Fra

ctio

n o

f to

tal

220-link

140-link

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Horn Antenna RPE

90 60 30 0 30 60 9040

30

20

10

0

Relative Power (dB)

Bearing (degrees)Azimuth Elevation

SLLSLLP e HPBW

28.2)1()(

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28GHz Antenna RPE

0 20 40 60 80 100 120 140 160 18040

30

20

10

00

40

dBsubs a( )

dBmesh b( )

1800 a b

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Main lobe Characteristics

0 2 4 6 8 10 12 1418

15

12

9

6

3

00

18

dBsubs a( )

dBmesh b( )

150 a b

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BS Interference (dBm) as a function of BS distance (km) and height (m)

BS distance (km)

BS

hei

ght a

bove

gro

und

(m)

Notes: Rayleigh parameter = 20m

System Spacing vs. BS Antenna Height

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MP-MP to PMP Subscriber Co-channel

heig

ht a

bove

gro

und

(m)

Distance from mesh (km)

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MP-MP to PMP Subscriber Co-channel (BS 12km from mesh edge)

Distance past BS from mesh (km)

He

igh

t a

bo

ve

gro

un

d

(m)

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Co-channel conclusions

• A mesh can be placed close to a PMP system, with negligible interference

• Spacing can be even less when the mesh uses “self adaptation” (down to zero?)

• Mesh antenna RPEs are not critical (low cost antennas can be used)

• Rain fading effects are negligible.

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Mesh to PMP hub (50m elevation) dry weather, adjacent channel

Interference power profile

0

0.5

1

1.5

2

2.5

3

3.5

4

-200 -150 -100 -50 0

Rx power (dBm)

Rel

ativ

e p

rob

abil

ity

0.0001

0.001

0.01

0.1

1

Cu

mu

lati

ve p

rob

abili

tyInterference

CDF

Threshold

BFWAtg(00)30

Mesh to PMP hub (50m elevation) dry weather, adjacent channel

Weather Max. interference power

Probability of exceeding threshold

Dry -82.2 dBm 37.4% Random rain front

-78.5 dBm 31.9%

Random rain storm

-79.4 dBm 36.0%

Uniform rain -78.7 dBm 28.2%

Mesh to PMP hub (50m elevation) dry weather, adjacent channel

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Mesh to 50m PMP hub: uniformly wet weather, single-channel guard band

Interference power profile

0

0.5

1

1.5

2

2.5

3

3.5

4

-200 -150 -100 -50 0Rx power (dBm)

Rel

ativ

e p

rob

abil

ity

0.0001

0.001

0.01

0.1

1

Cu

mu

lati

ve p

rob

abili

tyInterference

CDF

Threshold

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Mesh to PMP hub (50m elevation) one guard channel

Weather Max. interference

power Probability of exceeding threshold

Dry -103.2 dBm 0.00% Random rain front

-99.7 dBm 0.02%

Random rain storm

-100.4 dBm 0.00%

Uniform rain -99.7 dBm 0.02%

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Mesh to 25m PMP hub: uniformly wet weather, single-channel guard band

Interference power profile

00.5

11.5

2

2.53

3.54

-200 -150 -100 -50 0

Rx power (dBm)

Rel

ativ

e p

rob

abil

ity

0.0001

0.001

0.01

0.1

1

Cu

mu

lati

ve p

rob

abili

tyInterference

CDF

Threshold

BFWAtg(00)30

Mesh to PMP subscriber, adjacent channel

Interference power profile

0

0.51

1.52

2.5

33.5

4

-200 -150 -100 -50 0

Rx power (dBm)

Rel

ativ

e p

rob

abil

ity

0.0001

0.001

0.01

0.1

1

Cu

mu

lati

ve p

rob

abili

tyInterference

CDF

Threshold

BFWAtg(00)30

Weather Max. interference power

Probability of exceeding threshold

Dry -66.5 dBm 11.2% Random rain front

-70.0 dBm 12.1%

Random rain storm

-70.9 dBm 11.9%

Uniform rain -64.7 dBm 12.3%

Mesh to PMP subscriber, adjacent channel

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Mesh to cell-edge PMP subscriber, single-channel guard

band

Interference power profile

00.5

11.5

22.5

33.5

4

-200 -150 -100 -50 0

Rx power (dBm)

Rel

ativ

e p

rob

abil

ity

0.0001

0.001

0.01

0.1

1

Cu

mu

lati

ve p

rob

abili

tyInterference

CDF

Threshold

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Conclusions for Overlapping systems

• Guard band of zero to one channel is sufficient for a “random” mesh

• Self- adapting mesh can work with zero guard band• Antenna RPEs not critical (low cost antennas

possible)• Rain fading effects are negligible