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7.5.1
7.5.1
Initialy macro-cellular environment was implemented in SEAMCAT, but with time more flexibility was given to the tool to reproduce various topology options in cellular network (Figure 180). Cell sites are laid out in a hexagonal grid. Sites with omni-directional antennas are placed in the middle of the cells as depicted in Figure 176 and sites with tri-sector antennas are placed at the edge of the cells, where each site covers three cells. Figure 177 shows one of these cell sites (small hexagons in dashed lines) and that the arrows demonstrate the antenna orientation of each cell. The BS to BS distance (also refered as inter-site distance in the literature) is D. The cell radius R is equal to D/sqrt(3) in the omni-antenna case and is equal to D/3  in the tri-sector antenna case. Both suburban scenario and urban scenario can be modeled with this cell configuration. The scenarios differ only in propagation conditions and in the cell radius.

A wrap around cluster is used to reduce the number of cells required in the simulations and consequently to enable faster simulation run times. The number of cell sites in the cluster is assumed to be 19 (19 cells in the case of omnia-antenna and 57 cells in the case of tri-sector antenna), which appears to be appropriate for SEAMCAT simulation (see Section ‎7.6.3 for further details on wrap-around technique). 

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Figure 176: Macro-Cellular CDMA Network Deployment with Omni Antenna

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Figure 177: Macro-Cellular CDMA Network Deployment with Tri-Sector Antenna

Therefore SEAMCAT supplements a single considered CDMA / OFDMA cell with its Base Station (BS) two tiers of virtual cells to form a 19 cell (57 cell for tri-sector deployment) cluster, which is then populated with a certain number of mobile stations (MS) and a power control algorithm is then applied for balancing overall system, see Figure below: 

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Figure 178: 19 cells omni setup

CDMA and OFDMA module shares common platform like the positioning of the cellular layout. The celular topology in SEAMCAT is composed of the “Cell layout” and the “Cell radius”a shown in Figure 180.

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Figure 179: Cellular network positioning GUI

 

 

In the “Cell Layout” you can select 2 tiers, 1 tier or single cell layout. In addition, you can select between Omni dieectional (single sector),  tri-Sector (3GPP) and tri-Sector (3GPP2).

 The “Cell Radius” (km) is the size of the cell and defines also the BS to BS distance (i.e. inter-site distance). 

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Figure 180: Overview of the topology options in cellular network

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Figure 181 presents an example of the 3GPP approach:

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Figure 181: 3GPP illustration of the Cell Radius, Cell Range and BS to BS distance.

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Figure 182 (a) and (b) illustrate the 3GPP2 approach for tri-sector and omni-sector respectively

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Figure 182: 3GPP2 illustration of the Cell Radius, Cell Range and BS to BS distance for (a) tri-sector case and (b) omni-sector case

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From there it is possible to extract the cell radius in SEAMCAT.

 Table  

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Table 21: Example of the distances relationship between 3GPP and SEAMCAT

 

 

Urban Case

Rural Case

SEAMCAT cell radius (R)=

433 m

4330 m

SEAMCAT cell range (h)=

375 m

3750 m

Distance BS to BS (2h = 3 R1) =

750 m

7500 m

3GPP cell range (2R1) =

500 m

5000 m

3GPP cell radius (R1) =

250 m

2500 m

 

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