Antenna height calculation
Click the Antenna heights button on the Link design dialog. The hub sight antenna height must be set in point to multipoint applications.
If the operation is to create PTMP links and determine their feasibility, the antenna height calculation method will depend on the rejection criteria.
If the rejection criteria is antenna height, then do not check the "Limit remote antenna heights to the maximum specified value".
If the rejection criteria is diffraction loss, the "Limit remote antenna heights to the maximum specified value" must be checked and this maximum value specified.
The remote antenna heights will be calculated using the specified clearance criteria, unless a remote fixed height has been specified.
Transmission line length
Several options are provided to specify the transmission line length, The transmission line unit loss is specified under the equipment specifications section
Antenna coupling unit
Click the Antenna coupling unit button in the Link design dialog. The specific format of the data entry form will depend on the application (microwave, adaptive modulation or land mobile.
Point to multipoint equipment specifications
Click the Equipment specifications button in the Link design dialog. The equipment specifications in point to multipoint systems are part of the base station. This data is saved with the base station in the gr5 file. Note that in the case of point to point equipment specifications, the data is saved in the link design ld5 file. The point to multipoint dialog is organized into the following sections:
Hub (base station) sector antenna - radio data
Always do the data entry for sector 1. When sector 2 is initially selected, the data from sector 1 will be copied into sector 2. Manual data entry can be used for single sector omnidirectional antenna. In this case there will be no adjustment for vertical angles. Click the blue button for the base antenna code to access the antenna index. An antenna code is required for interference calculations and for multi sector antenna arrangements.
Manual data entry is adequate for coverage analysis. A radio code is required for interference analysis. Click the blue button for the base radio code to access the radio index.
Set the polarization and the channel id for an interference analysis.
Sector definition
A maximum of 8 sectors can be specified. The specific sector number to be displayed is set here.
symmetrical sectors - if this selection is checked, only the azimuth of sector 1 can be edited. The program will calculate the azimuth for the other sectors. If this is unchecked all sectors azimuths can be edited
Provision is made to set the same antenna and radio data and polarization in all sectors. Click the click the corresponding blue button
For interference analysis, click the blue button to load the frequency plan and identify the base station or remote site as the high frequency site.
Mobile (remote) antenna - radio data
Manual data entry can be used for the remote antenna. In this case there will be no adjustment for vertical angles. Click the blue button for the remote code to access the antenna index. An antenna code is required for interference calculations.
Manual data entry is adequate for coverage analysis. A radio code is required for interference analysis. Click the blue button for the remote radio code to access the radio index.
Transmission lines
If transmission line lengths have been specified for the base or remote antenna in the Antenna heights and transmission line lengths section, then click the blue button corresponding to that transmission line and select the transmission line. The transmission line data can also be entered manually.
Duplex and multiple access technology
The calculation of the composite interfering signal depends on the duplex and multiple access technology used in the radios. The duplex technology can be frequency or time division duplex - synchronized or non synchronized.
There are three options for duplex technology, and five options for multiple access technology. The technology is applied to every sector in the base station. There is currently no way to apply different technologies in different sectors of the same base station. The effect of each technology is explained below
Duplex technologies
Frequency Division Duplex (FDD)
Both the hub and the remotes transmit at the same time over different frequencies. All transmitters are considered in interference studies.
Time Division Duplex (TDD non synchronized)
With this technology only one of either the hub site or the remote sites in a sector are transmitting at a time. Therefore, in an interference study, only the worst case (between the hub and the combination of remotes) is taken in each sector. This would generally mean that only one frequency is being used for outgoing and incoming signals - and should be set as such in the channel plan.
Time Division Duplex (TDD synchronized)
This is a specialized form of duplexing between separate base stations. Hubs using this technology are synchronized with one another so that corresponding sectors will not be transmitting at the same time. There will be no interference cases between same numbered sectors of base stations using this technology.
Multiple access technology
Time Division Multiple Access (TDMA)
Only one remote per sector is transmitting at any time. Only one remote per sector is considered in interference cases. This will be the remote causing the worst interference.
Frequency Division Multiple Access (FDMA)
All remotes are transmitting simultaneously. All Interference cases are considered.
Code Division Multiple Access (CDMA)
All remotes are transmitting simultaneously. All Interference cases are considered. Power levels for remotes are adjusted so that the receive signal power at the hub from each remote is equal.
Orthogonal Frequency Division Multiple Access (OFDMA)
All remotes are transmitting simultaneously. All interference cases are considered.
Carrier Sense Multiple Access (CSMA)
This is also referred to as contention. This is form of TDMA where transmission inhibitted when the ransmitters have the ability to detect if another remote is transmitting and resolve the collision. In the program it is handled identically to TDMA..
Reliability parameters
The format will depend on the current multipath fade probability algorithm. Remember that this can be changed by selecting the Set PL50L options menu item. The dialog for each algorithm is shown below. The data entry requirements are self explanatory and are described in the transmission analysis section.
Rain parameters The format will depend on the current rain algorithm setting - Crane or ITU530. Remember that this can be changed by selecting the Set PL50L options menu item. The dialog for each algorithm is shown below.
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