How the interference area and site area calculated out in WinProp?
Answers
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I'm attaching an example project and two images.
The site area is the area served by one base-station site. It is the combination of the areas served by the transmitters on that site. Each transmitter serves one cell, so a site area may be the sum of two or three cell areas.
Each cell area is computed according to settings under the menu Project > Edit Project Parameter --> Air Interface tab. See the two images for the options.
For the interference, two things are considered. One is the thermal noise kTB times noise factor. This is usually low. The other is the received power from other base-station transmitters that operate on the same frequency. If they operate on another carrier frequency, they will not interfere.
Finally, after the cell assignment, the maximum data rate is determined from (1) received power from the transmitter that serves the cell, and (2) the signal-to-noise-and-inteference ratio (SNIR). Both have to be high enough to enable a certain data rate.
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mvogel said:
I'm attaching an example project and two images.
The site area is the area served by one base-station site. It is the combination of the areas served by the transmitters on that site. Each transmitter serves one cell, so a site area may be the sum of two or three cell areas.
Each cell area is computed according to settings under the menu Project > Edit Project Parameter --> Air Interface tab. See the two images for the options.
For the interference, two things are considered. One is the thermal noise kTB times noise factor. This is usually low. The other is the received power from other base-station transmitters that operate on the same frequency. If they operate on another carrier frequency, they will not interfere.
Finally, after the cell assignment, the maximum data rate is determined from (1) received power from the transmitter that serves the cell, and (2) the signal-to-noise-and-inteference ratio (SNIR). Both have to be high enough to enable a certain data rate.
Thank you very much for your reply!
May I ask for more details about how the interference is calculated about the "received power from other base-station transmitters that operate on the same frequency"? So if I understand correctly, the received powers from different BSs will be compared at one location point, the largest one will be from the main receiving BS, and the power from others will be seen as interference. And in the final calculation for the interference map, this power from others will be with some weight? If the calculation is only about power distribution, may I ask why it can not be calculated if I only set BS without setting Air Interface? Since the power distribution can be obtained without setting Air Interface. Thank you in advance!
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From the propagation results and the criteria for cell assignment, you know for every location which transmitter serves that location. Suppose the received power from that transmitter, at that location, is -35 dBm and the power from other transmitters that operate on the same frequency is -60 dBm. Then the signal-to-noise ratio is 25 dB.
You asked why this result is not available simply from the propagation results. (1) Depending on the cell assignment criteria, maybe in rare locations the strongest base station is not the serving base station. The cell-assignment calculation has been placed under network planning. (2) When you have multiple antennas on the same frequency, they can also be set up in such a way in WinProp that they help each other instead of interfere. This would be called a distributed antenna system (DAS), and the specifications are done as part of network-planning setup.
You asked about weights assigned to interfering stations. Good question. In the simplest approach, like in my calculation with -35 dBm and -60 dBm, all stations have the same weight. However, in LTE each carrier has many sub-carriers, and maybe not all carriers are used. Therefore, the Air Interface tab has a button for OFDM settings, and there a percentage overlap can be specified. Unfortunately, I don't see an effect of this setting on the results in my example project. Maybe I'm overlooking something.
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mvogel said:
From the propagation results and the criteria for cell assignment, you know for every location which transmitter serves that location. Suppose the received power from that transmitter, at that location, is -35 dBm and the power from other transmitters that operate on the same frequency is -60 dBm. Then the signal-to-noise ratio is 25 dB.
You asked why this result is not available simply from the propagation results. (1) Depending on the cell assignment criteria, maybe in rare locations the strongest base station is not the serving base station. The cell-assignment calculation has been placed under network planning. (2) When you have multiple antennas on the same frequency, they can also be set up in such a way in WinProp that they help each other instead of interfere. This would be called a distributed antenna system (DAS), and the specifications are done as part of network-planning setup.
You asked about weights assigned to interfering stations. Good question. In the simplest approach, like in my calculation with -35 dBm and -60 dBm, all stations have the same weight. However, in LTE each carrier has many sub-carriers, and maybe not all carriers are used. Therefore, the Air Interface tab has a button for OFDM settings, and there a percentage overlap can be specified. Unfortunately, I don't see an effect of this setting on the results in my example project. Maybe I'm overlooking something.
Thank you very much for your reply! I'm clear now.
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