wiki:Manual/Scenario/CDMA
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CDMA System tab

Whether you want to simulate CDMA UL (uplink) or CDMA DL (downlink), the upper part of the workspace display will allow you to select the system you want.


It is used to define the necessary parameters for the modeling of CDMA systems. The CDMA interface has been split into 2 tabs (when victim) or 3 tabs (when interferer):

Please consult the CDMA/OFDMA commonalities in terms of cellular topology, Pathloss and Effective Pathloss, Reference Cell etc...

General settings

6 panels characterised the CDMA system. The below graphic represent the CDMA UL when a victim.


The only difference with CDMA DL are the following 2 panels.


Identification

  • Library: allows to import/export the receiver characteristics from/to the library to/from the workspace.
  • name and description: You can name and write some description of the victim system you want to simulate.

CDMA general settings

Parameter Description

CDMA Link component

The type of CDMA System. There are considerable differences between modeling of uplink and a downlink in CDMA system.

Please consult the page on CDMA algorithms for a more detailed explanation of differences.

Receiver Noise Figure (dB)

Equipment-specific noise figure of receiver. It is used to calculate the thermal noise.

noise = -173.977 + 10*log10(systemBandwidth (MHz)) + receiverNoiseFigure (dB)

Handover margin (dB) Specifies the maximum difference between the links in users active list. The actual active-list selection is based on pathloss calculations.
Call drop threshold (dB) Used by power control to determine if a user should be dropped when not meeting exact target requirement.

Voice bit rate(kbps)

it is used to calculate the processing gain.

processingGain = 10*log10(systemBandwidth (MHz) / voiceBitRate (kbps) * 1000);

Reference bandwith (MHz) Bandwidth of the system. It is the same for either UL or DL.
Voice activity factor It is set to 1, i.e. 100% (all voice users that are generated are active). Contributions are invited to present algorithm where the percentage of voice active users in a system can be simulated
Minimum Coupling Loss (dB) The minimum path loss. It is used in the calculation of the effective path loss
Link Level Data Drop-down selection of Link level data look-up functions from Library. It is user's responsibility to choose an appropriate set of data. General workspace consistency check will check for Link direction and check if frequency difference between operating frequency and the nominal frequency of Link level data set is within 100 MHz

Receiver settings

This content of this panel depends whether CDMA system is a victim or an interfering system.

  • CDMA is a victim, you will have to set the blocking mask.

Transmitter settings

This content of this panel depends whether CDMA system is a victim or an interfering system.

This is only available if CDMA UL selected. Note that the number of optimised users is being re-calculated for each event. It is recommended to run the "simulate non-interfered capacity" so that SEAMCAT can provide a "best" optimised value, this will optimise the computation time afterwards. If you are using another number you risk to create an overhead in your computation time without any change in the output results.

Parameter Description
Target network noise rise Specific level of noise that the network is willing to handle, when this level is reached it starts removing UEs to reduce its noise level
cell noise rise selection Select the algorithm that allow the cell selection based on a noise rise increased. It is recommended to select it, when there is a single source/cluster of interferers geograhical located in a cell of the CDMA network. When the interferer is a network, it is recommended not use this option. The detail of the algoritm is available here.
Target cell noise rise (Available when Cell noise rise selection is active)If the cell noise rise is high, then it is difficult to find many cells with such situation (i.e. not all cells can experience a large increase of their noise) hence only a few, even only one will be selected. While if you set the threshold to a very low value, then you are allowing any new noise rise to be higher than the initial noise rise, hence you are considering all the cells (in an extreme case). The algorithm, recursively, try to identify the number of affected cells due to the a single source/cluster of interferers. It is set to 0.1 dB by default. There is an output in the CDMA UL that allow you to see per event how many cell are being affected
MS maximum transmit power Maximum transmit power of the MS (i.e. the UE)
MS power control range Span of the fluctuation of the power
PC convergence precision In the uplink, each mobile station perfectly achieves the target C/I, Eb/N0_target, during the power control loop convergence, assuming that the maximum transmit (TX) power, max_MS_Tx_Pw, is not exceeded. Those mobile stations not able to achieve Eb/N0_target after convergence of the power control loop are considered in outage (i.e. they are dropped). The power control loop is considered to converge when all mobile stations are within the max_MS_Tx_Pw and their Tx power is adjusted by less than the “PC convergence precision” value for the last power balancing iteration.

This panel is available only if CDMA DL selected.

Capacity for CDMA system

The capacity of the simulated system (i.e. how many mobiles per cell should be generated in the system) is dependent on all other settings and cannot always be easily deducted from these. Therefore SEAMCAT has a feature that allows for automatic determination of capacity. This is also known as simulation of non interfered capacity and is enabled by default.

Tip: The simulation of non-interferred capacity is a lengthy process. Therefore if you run multiple simulations with the same CDMA system (e.g. victim CDMA system unchanged and only interfering system is varied), then it would be sufficient to do the finding of non-interferred capacity in the first run. Then, having noted the result of non-interferred capacity finding exercise (may be seen by consulting the CDMA system view screen available after completion of simulations), in the following runs you may just set the obtained value as the constant user-defined value (i.e. option unchecked). Note: This assumes that you do not make any changes to the internal settings of the given CDMA system, that would otherwise have impact on loading capacity of the system.


ID Parameter Description
1 Simulate non interfered capacity Toggles automatic capacity finding. If the option Simulate non-interfered capacity is checked, then the system will automatically simulate the 'optimal' number of the mobiles for given system configuration (type of system, bandwidth, cell sizes, etc). The optimum finding algorithm is developed to establish the loading that would correspond to approx. 80% of maximum system capacity. If this option is unchecked, you are free to set a constant user-defined average number of mobile users per cell especially if the optimal capacity for the current scenario is known (this is often the case when running consecutive simulations with the same system) there is no need to simulate – as the simulation process can be quite lengthy. When this checkbox is disabled SEAMCAT uses the value entered in 2 – “Users per cell” as the capacity per cell.

2

Users per cell

If capacity simulation is enabled this indicates the starting point of the simulation. Selecting the right starting point can speed up the capacity finding. If capacity simulation is disabled the value in this field is the actual value used by SEAMCAT. Note:

  • SEAMCAT does NOT change this input value into the result of the simulation!
  • Users per cell is equal to UE per Base Station. SEAMCAT consider each Base station as its own cell.
3 Delta users per cell When SEAMCAT tries to find the optimal capacity it adjust the number of UEs per cell starting with this value. A proper value here can speed up capacity finding.
4 Number of trials When finding the optimal capacity SEAMCAT runs this (i.e. Number of trials) many snapshots of every value of UEs per cell before deciding whether or not the current value is the optimal capacity. Generally larger numbers mean greater precision but also longer time needed by the algorithm.
5 Tolerance of initial outage Downlink only – The tolerance of initial outage is the percentage of UEs that can be dropped before SEAMCAT determines that the tested number of UEs cannot fit into the system (i.e. 20 user_per_cell * 19 BS = 380 UEs, if 5% or less of 380 UEs are dropped, the system is considered able to handle/service 20 UEs per cell). SEAMCAT will adjust the value of UEs per cell untill a value is found which in 80% of the specified number of trials is able to handle the tested number of UEs per cell.This parameter allows for UEs in “extreme” pathloss situations to be “ignored” from the optimal capacity finding.
6 Target noise rise precision Uplink only – the precision used when comparing the noise rise of the filled system with target noise rise set under the “CDMA Uplink” panel

Propagation Model

This tab contains settings for the choice of propagation model to be applied when evaluating path losses in the internal links of the modeled CDMA system. Please see the guidance regarding separate information the choice and settings of the propagation models.

Positioning

5 panels characterised the positioning of a cellular system. Note that this panel is the same either a CDMA (UL/DL) or OFDMA (UL/DL) is simulated.


System

The celular topology in SEAMCAT is composed of the following:

  • Cell Layout: Selection between Omni dieectional and Tri-Sector antennas. SEAMCAT uses so called "non-cloverleaf" Tri-Sector cell layout. You can also select 2 tiers, 1tier or single cell layout
  • Cell Radius (km): this parameter is used to determine inte-rcell distance.

System layout

You can select where you want to position the reference cell in the cellular network.

System layout preview

You have the possibility to see a preview of the network you are simulating.

Mobile

Parameter Description
Antenna height (m) Height of user terminal in meters. Note that the assumed antenna height definition (above ground, above local clutter, effective antenna height) should correspond to the selected propagation model
Antenna gain (dB) An omni directional antenna is assumed
Mobility (km/h) Distribution used to specify simulated speed of users. Note that theese speeds have to conform to the speed options in the selected Link Level Data. For simplicity SEAMCAT assumes four different speeds, assigned to mobile users with uniform probability: 0 km/h - No movement, 3 km/h - Walking, 30 km/h - Urban driving, 100 km/h - Motorway driving

Base station

Parameter Description
Antenna height (m) Distribution used to determine height of BS. Note that the assumed antenna height definition (above ground, above local clutter, effective antenna height) should correspond to the selected propagation model
Antenna tilt (deg) equivalent to a physical tilt of an antenna on a mast, (-) sign is a downtilt, (+) sign is an uptilt

antenna pattern (see more details)

  • Library: allows to import/export the receiver characteristics from/to the library to/from the workspace.
  • name and description: You can name and write some description of the victim system you want to simulate.
  • Antenna peak gain (dBi)
  • Horizontal radiation pattern
  • Vertical radiation pattern
  • Spherical radiation pattern

Transmitter to Victim Link Receiver Path

When CDMA is an interferer an extra tab is accessible to set the characteristic of the path between the interferig transmitter (UE for UL or BS for DL) and the victim system.

Attachments