Estimating number of base stations based upon handsets
The following requirements must be considered when estimating how many base stations are needed and deciding where they should be placed:
- DECT radio coverage of the entire site.
- Number of connection channels to avoid capacity bottlenecks.
- Base station overlap for synchronization to guarantee roaming and handover.
The following table shows the maximum number of connection channels and handsets that can be handled in relation to the number of FON-D72-B base stations:
|
FON-D72-B |
Connection channels |
Active handsets |
|---|---|---|
|
1 |
8 |
8 |
|
2 |
16 |
16 |
|
3 |
24 |
24 |
|
4 |
32 |
32 |
|
5 |
40 |
40 |
|
6 |
48 |
48 |
|
7 |
50 |
50 |
|
8 |
50 |
50 |
|
9 |
50 |
50 |
|
10 |
50 |
50 |
|
11 |
88 |
88 |
|
12 |
96 |
96 |
|
13 |
100 |
100 |
|
14 |
100 |
100 |
The capacity of the multi-cell system must be high enough to guarantee that subscribers can be reached in high-density traffic. The capacity of the multi-cell system is determined by the following:
- Number of connection channels available. Connection channels are used for phone calls and for list access actions (when the handset accesses the History or Directory).
- Grade of service (GoS) determines the number of connections that may not be achieved due to the system being at full capacity. With a grade of service of 5%, it is permissible for 5% of 300 calls (15 connections) not to be established. This means that only 285 connections have to be achieved.
To calculate the number of connection channels required, use the following formula:
(<Number of calls per hour> – (<Number of calls per hour> x <GoS%>)) x <Average length of call per hour> / 60 min.
As an example, you set the GoS at 5% and you require 300 calls per hour at an average length of 5 minutes each. The equation would be: (300 – (300 x 5%)) x 5/60 = 23.75. This means that 24 connection channels would be required, and you would need 3 base stations.
Since the traffic volume is not normally evenly distributed over the site to be covered, the traffic volume must be calculated for each area (offices, hotspots, stairwells) to determine the number of base stations that need to be installed.