Link Budget Design with Pathloss 4.0

LINK BUDGET DESIGN WITH PATHLOSS 4.0

Jonnathan Romero Nov 2006

1

Link Budget Design with Pathloss 4.0

INTRODUCTION The following document has been created to establish standards on design criteria for Point to Point radiolink system PDH and SDH with the software PATHLOSS 4.0, module Worksheet. This method will be used as an initial guideline. It can be modify according to the designer experience. Recommendations from International Telecommunication Union (ITU) to use: Unavailability and Outage Calculation according to ITU-R: 530-7. The SDH and PDH links will be defined as Long Haul y Short Haul respectively in the National Portion (ITU-T G-826) STEP 1: Verify that you are using the same Datum that your maps and/or GPS; i.e. Datum WGS84. You can find it at Configure –> Geographic Default

STEP 2: Input the coordinates in the Summary Module. It’s recommended to put the operation frequency. Here, it also can be input the antenna heights, if they are known. STEP 3: Go to Terrain Data Module. Input the terrain data. This data can be taken from cartographical or digital maps. Note: This is useful for evaluating terrain type according to 530-7 classification: Plain, Hills or Mountains. STEP 4:Set the antenna heights directly in the Summary Module or using the Antenna Heights Module. It is necessary to set if it is a space diversity link or not. This can be done clicking at Configure –> Antenna Configuration:

2

Link Budget Design with Pathloss 4.0

STEP 5: WORKSHEET MODULE In this module is highly recommended to have a procedure for filling up the values. Here is presented a small routine:

A. Channels (Optional) B. Radios C. Main Antennas D. Waveguides (Main) E. Branching and Circulators Loss (Main) F. Diversity Antennas G. Waveguides (Diversity) H. Branching and Circulators Loss (Diversity) I. Menu: Operations –> Reliability Methods J. Menu: Operations –> Diversity Calculation K. Menu: Operations –> Options L. Rain M. Path/Terrain Description N. Menu: Report –>Full Report

Description:

Without Space Div With Space Div

A

B

C

D

E

F G

I-J-K N

L

MH

3

Link Budget Design with Pathloss 4.0

A. Channels (Optional)

you put channel frequencies, the program can calculate frequency spacing when you

B. Radios

adios must be chosen with: Use 10-3 Parameters. It’s necessary that the radio data

C. Main Antennas.

Use the normal selection procedure

D. Waveguide (Main)

se the normal selection procedure. It’s necessary to take in account the antenna height,

E. Branching and Circulators Loss (Main)

ome databases include these values in the Power Output and the Receive Threshold. If

F. Diversity Antenna

ame procedure done for Main Antennas

G. Waveguide (Diversity)

ame procedure done for Main Antennas waveguides

H. Branching and Circulator Loss (Diversity)

ame procedure done for Main. Remember that this value can be different from Main. It

I. Menu: Operations –> Reliability Methods

Ifhave frequency diversity, and calculate frequency improvement. Also, for advance users, it’s necessary for interference calculation.

Rcomes with Signature information.

Uthe distance shelter-tower, distance inside the shelter, distance from the vertical ladder to the antenna position.

Sthis is happens, the Tx and Rx levels are obtained in the waveguide port (C-C’). The fade margin would be the same if we consider B-B’ or C-C’ (with all losses)

S

S

Sdepends of the type of radio. For example: In a 1+1 HSB the asymmetrical splitter separate 1.5dB for Main and 3.5dB for Space or protection.

4

Link Budget Design with Pathloss 4.0

Reliability Method: ITU-R P.530-7/8. This will calculate the Flat Fading Margin accordingly to this recommendation Calculation Method: Select ITU-G.821 for only to obtain: Worst Month SES and Unavailability for a 10-3 Fade margin. Note: This is for SDH and PDH. This option set the calculation accordingly to Rec ITU-R P. 530-7. Regional Standards: ITU-R P.530 strict – equipment signature. Type: SDH or PDH. This doesn’t affect the calculation is only for information Treat multipath as: SES only. Time percentages: Select 0.0001%.

J. Menu: Operations –> Diversity Calculation

5

Link Budget Design with Pathloss 4.0

Space Diversity Operation: Select Baseband Switching if the diversity radio doesn’t have IF combiner. This value this value should be in the radio data file. If Pathloss can not find it, it set a value of 2.6dB for the diversity Improvement factor on the radio with combiner. Frequency Diversity: This value can be calculated with the frequency channel automatically. It’s recommended to put here the worst case: Adjacent channel distance. If the radio comes Co-channel (XPIC functionality) this value is zero. Maximum Diversity Improvement: Leave empty.

K. Menu: Operations –> Options

Assign a water vapour value according to the country and the region (23-30 gr/m3). A typical value for coastal region or islands is 30 gr/m3. This value does not affect to much the calculation (±0.05 dB some cases).

L. Rain

Method: ITU-R P.530-7/8. Select 110 mm/hr Polarization: This value determinate the polarization used for the calculation. Changing this value does not affect the polarization of the channel assignment. If the link has vertical and horizontal channels it’s recommended to set this value to Horizontal. If the link works in horizontal, it will do it in vertical.

M. Terrain Data

In the first screen, Path Profile Data, only modify Diffraction Loss value, if it exists. Select in this window menu: Geo Clim. A new form will appear as follows:

Latitude, Longitude: These values are calculated automatically with the link coordinates. Path Classification: It’s Surveyor responsibility to determine the path classification according to the profile and antenna height (above sea level). It will be Plain, Hills or

6

Link Budget Design with Pathloss 4.0

Mountains as per Rec. 530-7 definition. The interval heights (0-400m, 400-700m, >700m) must be selected. This is not automatically calculated. Probability dN/dh < -100 Nunits / km (%): PL = 20% (Caribbean Countries). Small islands it should be considered to use 30% Use over water modifications: Select this option if this is a coastal link (see 530-7 definition). Rc (0 to 1): Indicate what is the percentage of the link that is coastal. If it is 60%, set this value to 0.6

N. Menu: Report –>Full Report

COMPARISON: The outage value defines the comparison criteria. In Digicel we use SDH links for Backbone and PDH for last mile links. In ITU-T G.826 they are defined as Long Haul and Short Haul. When ITU-T recommends some values to be accomplished by the operators, DIGICEL has chosen to customize the requirements. The ITU-T has changed those requirements and today they depend on the link distance and its classification. DIGICEL has kept the customized requirements, and they are as follows: I. - PDH LINK (SHORT HAUL): RAIN/MULTIPATH: Only the links over 10 GHz are considered affected by rain. The fade margin should be:

• For links ≤ 10GHz: Fade Margin > 30 dB • For links > 10GHz: Fade Margin ≥ 35 dB • For links > 13GHz: Fade Margin ≥ 39 dB

All of them must have less than 0.01% of outage or unavailability (99.99% time available) II. - SDH LINK (LONG HAUL): RAIN/MULTIPATH: Only the links over 10 GHz are considered affected by rain. The fade margin should be:

• For links ≤ 10GHz: Fade Margin > 32 dB • For links > 10GHz: Fade Margin ≥ 37 dB • For links > 13GHz: Fade Margin ≥ 40 dB

All of them must have less than 0.001% of outage or unavailability (99.999% time available)

7