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HUAWEI TECHNOLOGIES Co., Ltd. HUAWEI Confidential Page 2

Microwave Frequency Planning

Purpose of frequency planning:

Make reasonable use of the frequency resources

so that the new microwave links and existing onesdo not interfere with each other and the system

availability of the microwave network can be

ensured. In the process of planning for the

microwave network, appropriate frequency bands

and channels should be selected and interference

avoidance should also be taken into account.


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Microwave frequency bands suggested by ITU-R for common use:

Frequency

Band

4 GHz L6 GHz U6 GHz 7 GHz 8 GHz 11 GHz 13 GHz 15 GHz 18 GHz 23 GHz 26 GHz 38 GHz

Range 3.6-4.2 5.9-6.4 6.4-7.1 7.1-7.7 7.7-8.5 10.7-11.7 12.7-13.2 14.5-15.3 17.7-19.7 21.1-23.6 24.5-26.5 37.0-39.5


Division of microwave frequency bands:

LF MF HF VHF UHF SHF EHF

Microwave

10 Km 1 Km 100 m 10 m 1 m 10 cm 1 cm 1 mm

f 30 KHz 300 KHz 3 MHz 30 MHz 300 MHz 3 GHz 30 GHz 300 GHz

Infrared

rays

Visible

light


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Microwave Frequency PlanningPrinciples of selecting proper frequency bands:

1. Select proper frequency bands according to the frequency resources (licenses) owned by

the carriers and the stipulations of local radio management committees.

2. Select proper frequency bands according to the characteristics of the designed networks

and routes. For example, high-frequency bands are generally used for mobile networks

and MANs because quite a few channels available at high-frequency bands.

3. Select proper frequency bands according to their characteristics.

Low-frequency bands (L6G/U6G/7G/8G/11G) are suitable for long-distance links and

high-frequency bands (13G/15G/18G/23G/26G/38G) are suitable for short-distance

links.

Due to the limited number of channels existing at low-frequency bands, interference

tends to arise in the long-distance transmission.

High-frequency bands are suitable for high-speed data transmission and interference

sustainable because there are many channels with broad bandwidth.

High-frequency antennas feature high gains. Compared with low-frequency bands, high-

frequency bands require small clearance. Towers with these antennas properly used can

be lower than others.


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Illustration of the selection of microwave frequency bands:

85432 10 201 30 40 50

1.5 2.5LAN/PCS

Long-distancebackbone networks

Area, local, and edge networks

28

34Mbit/s

34140155

Mbit/s28

34140155

Mbit/s

3.3

11 GHz

GHz


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Division of microwave frequency bands:

Frequency Shift Frequencies (MHz) (T-R Spacing) Use

4-7 GHz 161, 154, 245 Long-distance network

backbones

8 GHz 126, 161, 154. 199, 266, 311 Long-distance network

backbones

11-13 GHz 266 Short and medium distance

15 GHz 308, 420, 490, 315. 720, 728 Short and medium distance

18 GHz 340, 1092.5, 1008, 1010, 1560 Short and medium distance

23 GHz 600, 1050, 1232, 1008, 1200, Short distance in urban areas

26 GHz 855, 1008 Short distance in urban areas

28 GHz 1008 Short distance in urban areas

32 GHz 812 Short distance in urban areas

38 GHz 700, 1260 Short distance in urban areas


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Figure 1 for configuring microwave radio frequency channels:

Channel number

Frequency

F3

F1F2

Fo

1 2 n 1' n'

Lower half band Upper half band

Center frequencyFo: center frequency

2'


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Figure 2 for configuring microwave radio frequency channels:

Each channel consists of a pair of transmission and receiving frequencies.

TxRxTxRx

Channel Channel11'nn'

11'nn'

High site Low siteThe site which the receiving frequency higher than

transmitting frequency is called a high site.The site which the receiving frequency is lower than

the transmitting frequency is called a low site.


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Principles of selecting proper bandwidth of microwave channels:

The bandwidth of a microwave channel is decided by the signal rate and radio

modulation scheme.

The most commonly used ways are the quadrature phase shift keying (QPSK) and

quadrature amplitude modulation (QAM).

2 x E1 requires 3.5 MHz (QPSK) 4 x E1 requires 7 MHZ (QPSK)

8 x E1 requires 14 MHz (QPSK)

16 x E1 requires 28 MHz (QPSK)

STM-1 requires 28 MHz (128QAM)

The more advanced modulation is, the smaller the bandwidth is required.

The 16E1 signal subject to QPSK requires the same bandwidth (28 MHz) as the STM-1

signal subject to 128 QAM does.


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Principles of selecting proper microwave channels:

1. Try not to select the special frequency resources (licensed) used by other carriers even if

these frequency bands are not used in some areas (in case they may be used in the future).

2. If the planned microwave link features the same routing or parallel routing as another

microwave link, it is recommended that the frequency band/channels different from those of

the existing link are used. A different polarization mode should be configured even if the

same channel is adopted as a result of the little interference and big margin proved by the

calculation and analysis.

3. If the angle between two interleaving routes is comparatively small (for example, smaller

than 30 degrees), a different channel should be selected. If the angle is quite large (for

example, larger than 60 degrees), the same channel can be used provided a different

polarization mode is configured. The same channel with the same polarization mode can be

used only when the angle is larger than 90 degrees. This is a generally adopted principle for

microwave frequency planning. For different equipment, antenna configuration, or capacity,

analysis should be made on the link accordingly.

4. In the design, the microwave link should be as far from the scatter communication station

and the satellite communications earth station as possible. When the antenna of the

microwave station is directed to the satellite orbit with a tolerance of2 degrees, thefrequency band of the communication satellite cannot be used.


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Example for the microwave frequency planning:

In frequency planning, reusing of frequency resources should be taken

into account, the internal and external interference should be avoided,and the link quality should be enhanced.

Polarization should alternate every other hop for the decrease of

overreach interference. The polarization configured alternate every hop

is conducive to the decrease of front-back interference upon the

antenna.

1H 1H 1V

1V

2H

1H


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Two-frequency system and quadruple-frequency system used

in microwave frequency planning:

For the 1+1 system or 2+0 system of the frequency diversity, the use of the two-

frequency system can save the frequency resources, while the use of the quadruple-

frequency system can decrease the internal and external interference and enhance the

link quality. Whether to select the two-frequency system or the quadruple-frequency

system depends on the interference within the planned microwave network system and

the mutual interference between the microwave links to be established and the linksexisting in the system.

Case 1: When the link to be

established interleaves with an

existing one, the two-frequency

system can be used for the

former provided the samesystem is used for the existing

link, and a different channel

should be selected in this case.Existing link

Link to be established


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Two-frequency system and quadruple-frequency system used in

microwave frequency planning:


established interleaves with an

existing one, the quadruple-

frequency system can be used

for the former provided the

same system is used for the

existing link. In this case, the

neighboring links should have

different channels.

Existing link

Link to be established


established has a branch,the quadruple-frequency

system should also be

used for this branch.

2,4


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Two-frequency system and quadruple-frequency system

used in microwave frequency planning:

Case 4: When the link to be established

forms a loop-line with quite small angles,

the quadruple-frequency system should

be selected.

Case 5: When the routing deflection angles

are too great, but the angles of La and Lb are

quite small, for example, smaller than 15

degrees, comparatively great overreach

interference may occur if the two-frequency

system is selected for Site A and Site D.

Therefore, the quadruple-frequency system

should also be used in this case.

1,3AB

C

D

2,4La

Lb

Case 6: The quadruple-frequency system should also be selected in such circumstances as the

front-back ratio difference of the antenna is smaller than 60dB, the SWR(Standing Wave Ratio) of

the antenna feeder is large, and the equipment has weak immunity to interference.


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Selection of proper frequency diversity channels:

When the microwave link is designed to adopt the frequency diversity protection,attention should be paid to the selection of channel spacing between the master

channel and diversity channel. The formula to calculate the improvement in the

frequency diversity is as follows:

d/1080 210/ ffI CFM

FD

where

FDI : frequency diversity improvement

f : frequency spacing between the master channel and diversity channel

f : Radio center frequency

CFM : flat fade margin

d : transmission section length

From the formula, we can find that the improvement in the frequency diversity is proportional to the

channel spacing. Generally, the channel spacing should be at least 2 times of the radio frequency

bandwidth. For a greater improvement in the diversity, the channel spacing should be as large as

possible.


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Case Study for Microwave Frequency Planning

Case study purpose: to be familiar with the preceding rules for microwave frequencyplanning and apply them to practice.

Project area: Mauritius in the Eastern Hemisphere and Southern Hemisphere

Requirement of the longitude

and latitude of the site:

Frequency resource: assigned by the user, 7G/28M: 2 chs; 8G/7M: 4 chs

Contents of planning:

Channel planning

High and low sites configuration

Configuration of the polarization mode for the channel

GSM Network frequency planning in Mauritius:


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Legend:

Complete the routing and capacity planning by referring to the

right map:

STM-1

8E1

4E1

New relay stations

Service hub

BTS


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Proper channels of different bandwidths should be selected according to the capacity ofthe microwave link and frequency resource the user owns.

Frequency resource owned by the user:

Channel selection 1:

Channel No. Frequency Channel No. Frequency

1h 7610 1l 7442

3h 7666 3l 7498

7G: 7.4-7.7; number of channels: 2; channel spacing: 28 MHz


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Proper channels of different bandwidths should be selected according to the capacity

of the microwave link and frequency resource the user owns.





1h 8178 1l 7912

2h 8192 2l 7926


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1h 8178 1l 7912

2h 8185 2l 7919

3h 8192 3l 79264h 8199 4l 7933


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The following channels are selected according to the capacity of the link:


For STM-1, select f1 and f3 channels (7425-7725) with 28 MHz bandwidth.

For 8E1 PDH, select f1 and f2 channels (7900-8400) with 14 MHz bandwidth.

For 4E1 PDH, select f1, f2, f3, and f4 channels (7900-8400) with 7MHz bandwidth.


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Implement the frequency planning in Pathloss by using the preceding rules flexibly.

Points to be noted in frequency planning:

Frequency planning in Pathloss:

1. All microwave sites must clearly mark the CALL SIGN, which cannot be the

same and will be used in the later interference calculation.

2. Two-frequency system. To prevent the co-channel interference, a site should

use different channels for multi-directions.

3. Deploy the sites in such a way as high sites and low ones alternate. Check the

interference calculation report to see whether this principle is observed.

4. Configure the sites with two polarization modes as required.


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Example for frequency planning in Pathloss:


1. Access the PL4.0 program.

2. Log in to the network module.

3. Open the completed routing file.

4. Take the link between Site 5 and Site 21 for instance. Set the CH parameters

after setting the parameters for Radio and Antennas.

5. Click CH. The TX Channelsdialog box is displayed, as shown in the next page.


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Click CH. The TX

Channelsdialog box

is displayed, as

shown in the figure

on the right side :



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Click Lookup. In

the Filedialog box

that is displayed,

click Openand

select the

corresponding

frequency planning

file from Freqplan,

as shown in the

figure on the right

side.



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Open the target

frequency planning

file, as shown in

the figure on the

right side :


C St d f Mi F Pl i


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SDH adopts the hotbackup system. Select

f1 channel with 7 GHz

bandwidth as required,

and then select the

proper frequency for

use, site 1 as the high

site, and the vertical

polarization mode

before returning to the

previous page and

finally click OK, as

shown in the figure on

the right side:


C St d f Mi F Pl i


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According to the

two-frequency

system, the

frequency planning

for the SDH

backbone ring is

completed, as

shown in the figureon the right side:


C St d f Mi F Pl i


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According to the two-frequency

system, the frequency

planning for the SDH

backbone ring is completed, as

shown in the figure on the right

side.

Note that a site (Site 5) in the

ring has both high and low

stations due to the odd number

of the BTSs. In frequencyplanning processes, this

should be avoided.


Site 5/2

Site 21/1

Site 25/1

Site 44/1

Site 35/1

ADD1

ADD2

C St d f Mi F Pl i


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Statistics about the

frequency planning

for the SDH

backbone ring:


Site Name 1 Site Name 2Frequency/Polarization

Mode

Site 5 (high) Site 21 (low) 1/V

Site 21 (low) Site 35 (high) 3/V

Site 35 (high) Site 44 (low) 1/H

Site 44 (low) Site 25 (high) 3/H

Site 25 (high) ADD 2 (low) 1/V

ADD 2 (low) ADD 1 (high) 3/V

ADD 1 (high) Site 5 (low) 3/H

Case St d for Micro a e Freq enc Planning


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Take Site 21 for

instance. In Pathloss,

implement the

frequency planning forthe link of 8E1. Select

the 1+1 hot backup

mode, f1 channel in 8

GHz bandwidth, and

vertical polarization,

as shown in the figure

on the right side:




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Take Site 21 for

instance. The result

of the frequency

planning for the link

of 8E1 is shown in

the figure on the

right side:


8E1

frequencyconfiguration



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Take Site 21 for

instance. The result

of the frequency

planning for the link

of 4E1 is shown in

the figure on the

right side:




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The 2-hop SDH link, 1-hop 8E1 link,

and 3-hop 4E1 link converge at Site

21. As 4E1 has quite a few links, try

to select different channels in the

direction of 8E1 links to reduce the

interference. In this case, f1, f3, and

f4 channels with 8 GHz bandwidth

are selected and a different

polarization mode is adopted. The

statistics about the frequency

planning for Site 21 are listed in the

table on the right side:


Site

Names 1

Site

Names 2

Equipment Planned

Frequency

T R

Site 21

(low)

Site 8

(high)

4E1 4H 7933 8199

Site 21

(low)

Site 38

(high)

4E1 3V 7926 8192

Site 21

(low)

Site 39

(high)

4E1 1H 7912 8178



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The result of the

frequency

planning for Site

21 is shown in

the figure on the

right side:


Site 5

Site 21

Site 35

Site 8

Site 38

Site 39


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Complete all frequency planning for the microwave network according to

the relevant principles and output the design result. The frequency

configuration in the software will be used for the future interference analysis.



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Microwave Network Planning and Design - Frequency Planning

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