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ver. 08-02-05 Alvarion Training Services

1

2/12/2008

Radio Planning and Systems CollocationRadio Planning and Systems Collocation

22

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In This Chapter

Collocation effects of adjacent / overlapped cells

Frequency and power considerations

Radio Planning Tools and Calculations

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Chapter Objectives

This chapter enables you to:

Identify the problem effects between adjacent cells

Name the minimum physical separation between cells

Describe the relevant radio planning considerations and identify somepower budget calculationsList some radio planning tools (NIR, limitation of the automatic

channel

selection).

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In This Chapter




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Adjacent Cells

Each cell - 6 SectorsFrequency effects

10

9

2

1

5

6

10

92

1

5

6

10

9

2

1

5

6

Adjacent Cells

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Adjacent and Overlapped Sectors

10

92

1

5

6

10

9

2

1

5

6

Overlapped Sectors

Adjacent Sectors

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Collocation Cells Frequencies SeparationCollocation is achieved by operating collocated systemson different channels

Channel Band-Width: 10, 20 or (in BreezeNET-B) 40 MHz

5730 MHz

1 3 5 7

2 4 6

9

8 10

U-

NII

110 MHz (ISM)

5840 MHz

Adjacent channels

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Collocation Cells Frequencies SeparationMechanically adjacent or overlapped sectors can not usefrequency adjacent channels

At least one operating channel should be kept as guard

channel. Doing otherwise may cause Adjacent ChannelInterference (ACI) and reduce the performance of both

systems

Is not recommended reusing the same frequencychannel in back to back configuration

3

54

Adjacent ChannelsPartial

Overlapping Sectors

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Collocation Cells Frequencies SeparationIn back-to-back installation a separation of 1 channel isrecommended

Back-to-Back Sectors

3

5

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U-

NII7

53

Collocation Dos and Donts

1

59

1 3 5 7

2 4 6

9

8 10

5740 MHz 5760 MHz 5780 MHz 5800 MHz 5820 MHz

5750 MHz 5770 MHz 5790 MHz 5810 MHz 5830 MHz

1

73

9

10

9

2

1

5

6

Possible cell configuration when

using 10 MHz channels

Possible cell configuration when

using 20 MHz channels

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In most cases of elevated noise floor the cause is other

equipment, co-located on the same tower or rooftop.

Co-channel InterferenceWhen the noise floor is elevated by a signal that is on the

same frequency as your radio

Adjacent Channel Interference

When the noise floor is elevated by a signal that is not on

the same frequency as your radio but rather an adjacent

channel.

Adjacent & Co-channel Interference

Co channel and adjacent channel interference may be caused by:

Wrong frequency allocation

Wrong transmit power configuration

Low antennas physical separation or faulty antennas

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Typical 3 Sector Site

1

23

Collocated Noise Sources

When 1 transmits, 2 & 3

also receive energy fromthe back of the antenna.

If radio 2 or 3 are on or

near the same frequency

as 1, then the resultwould be co-channel

interference.

Co-channel interference

is the most destructive

type of interference.

Green arrow indicates

desired direction of

transmission

Red arrow indicates

energy is released

from the back and

sides of the antenna

as well.

S t A t Ph i l S ti

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Sector Antennas Physical Separation - Installation GuidelinesAntennas Installed at the Same Height

Recommended distance between sector antennas:

Adjacent/Overlapped sectors: 2 meters

Back-to-Back sectors: 5 meters

Shift Angle Between Antennas Back to Back

S t A t Ph i l S ti

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Sector Antennas Physical Separation - Installation GuidelinesFor installation where the recommended physical

separation cant be met, it is recommended to mix the

horizontal and vertical separation as follows:

Overlapped Sectors Adjacent Sectors

< 2m

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OMNI antennas transmit energy in all directions

Energy may be high enough to raise the noise floor on nearby sectoral

antennas.Is recommended a 2m separation between sectorial antennas and other

equipments installed on the same pipe/tower

Collocated Non BA-VL Noise Sources

2m

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In This Chapter




Adjacent Sectors

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Adjacent Sectors- General ConsiderationsA very close to the center => Signal could saturate AU Sector #2A and B transmit on different (but close) frequencies

The AU Sector #2 couldnt receive B

Solution -

ATPC (Automatic Transmit Power Control)

B

Adjacent Cells / Sectors

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Adjacent Cells / Sectors- Frequency ConsiderationsSmall CellsC transmissions to AU Sector #2 reach AU Sector #1 causinginterference to AU Sector #1

Solutions

- ATPC-

Rotate the cell frequency pattern -

Avoid using same sequence in

sectors illuminating the same direction

Base Station #1 Base Station #2

C

Adjacent Cells / Sectors

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Adjacent Cells / Sectors- Frequency Considerations

Cell #1 Cell #2

Sectors #2 in cells #1 and #2 use same frequencySignal from sector #2 (cell #1) can reach C and cause interference

Solutions

-

Rotate the cell frequency pattern -

Avoid using same sequence in sectors

illuminating the same direction-

If the previous solution cant be applied, reduce the transmit power of

sector #2 (Cell #1)

C

C

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In This Chapter




P B d t C l l ti

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Power Budget Calculation

PR

= PT LT + GT LFS + GR LR FM

While

P

T

LT

+ GT

EIRP

Our Goal PR SRAU-IDU

AU-ODU

C

AT-5Cable

SU-IDU

SU-ODUCAT-5Cab

le

PT

LT

GT

LFS

GR

LR

PR

PR = Received Power [dBm]

SR = Receiver Sensitivity [dBm]

PT = Transmit Power [dBm]LT = Cable Loss at the transmitter side [dBm]

GT = Gain of transmitter Antenna [dBi]

LFS = Loss of Free Space [dBm]

GR = Gain of the Receiver Antenna [dBi]LR = Cable Loss at the Receiver side [dBm]

FM = Required Fade Margin

S t S iti it

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System Sensitivity

Modulation

Level

Sensitivity

(H/W Rev. B and Higher)Minimum

SNR

1 -89 dBm 6 dB

2 -88 dBm 7 dB

3 -86 dBm 9 dB

4 -84 dBm 11 dB

5 -81 dBm 14 dB

6 -77 dBm 18 dB

7 -73 dBm 22 dB

8 -71 dBm 23 dB

P B d t C l l ti E l

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Power Budget Calculation - Example

AU-IDU

AU-ODU

C

AT-5Cable

SU-IDU

SU-ODUCAT-5Cab

le

PT

LT

GT

LFS

GR

LR

PR

Note

LFS

= 92.5 + 20 Log + 20 Log

PR = Received Power [dBm]???

PT = Maximum PowerLT = 0.25 dB per meter (Length of 2m)

GT = 17 dBi (90

Antenna)

LFS = Frequency 5.8 GHz; Distance of 10 Km

GR = 21 dBiLR = Attached Antenna

FM = Rural environment / obstacle LoS (Typically 10 dB)

EIRP

= 36 dBm (FCC 5.8 GHz)

Po er B dget Calc lation E ample

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Power Budget Calculation - Example

PR

= 19.5 0.5 + 17 127.67 + 21 0 10While

19.5

0.5

+ 17

36

Our Goal -80.67 SRAU-IDU

AU-ODU

C

AT-5Cable

SU-IDU

SU-ODUCAT-5Cab

le

19.5

0.5

17

127.67

21

0

PR

PR = Received Power [dBm] -81.67 dBm

PT = Maximum Power+19.5 dBmLT = 0.25 dB per meter (Length of 2m)

GT = 17 dBi (90

Antenna)

LFS = Frequency 5.8 GHz; Distance of 10 Km

GR = 21 dBi

LR = Attached Antenna

FM = Rural environment / obstacle LoS (Typically 10 dB)

EIRP

= 36 dBm (FCC 5.8 GHz)

The system will work at leastin modulation level 5

Radio Planning Tool (NIR)

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Radio Planning Tool (NIR)

Runs on Win95, Win98 orWinNT

Inputs from user

3D geographical mapsRadio parameters

Antenna parameters

Site parameters

Capacity requirements

Output of the Radio

Planning Tool

Power coverage => availablecapacity

User affiliation to Base StationsNIR application

Note: For limited size cells (micro cells) the AU transmit power may be required to be reduced

according to the desired covered area and modulation level in order to allow a betterfrequency reuse

26Spectrum Analyzer Feature

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p y Channel Selection

In this mode the AU only listens and does not operateas normalWhen The feature is turned on, the AU:

ResetsScans the spectrum for as long as configured

When Automatic channel selection option is enabled,

Automatically selects the clearest

channel upon scanning

completion (Disabled by default)

Resets and goes back to its normal mode (After completion)

The results may be viewed (During this period)

The feature exists both in AU and SUThe AU automatic channel selection feature does not

take in account the OFDM interference (OFDM Frames

from the spectrum analyzer table)

27Spectrum Analyzer Feature

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p y Channel Selection

Spectrum Analysis Status : Active

Spectrum Scan Channel Period : 5

Spectrum Scan Cycles : 2

Automatic Channel Selection : Disable

Channel SignalCount

SignalSNR

SignalWidth

OFDMFrames

5725 115 4 7 0

5730 10 4 22 0

5735 0 0 0 0

5740 6 7 14 211

5745 451 13 14 65

5750 256 20 220 0

5755 15 6 56 0

5780 0 0 0 0

5785 0 0 0 0

5790 0 0 0 05795 0 0 0 0

28 Frequency Allocation Case Study

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Frequency Allocation Case Study

Is there a mistake in

this Radio Planning?

5,500 MHz

5,700 MHz

5,520 MHz

5,540 MHz

5,560 MHz

5,580 MHz

5,600 MHz

5,620 MHz

5,640 MHz

5,660 MHz

5,680 MHz

29 Summary

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Summary

The main problems due to Collocation of Cells

Main radio planning considerations

Radio planning tools to optimize the situation

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