Traffic Capacity Of The Base Stations - Avaya DECT R4 Installation And Administration Manual

Planning an IP-DECT system
mE
50
100
150
200
Example:
A customer ordering a system with 55 cordless phones, generating 200 mE each in average,
requires a system with a traffic capacity of 11 E. With an accepted GOS of 0.5% the number of
base stations is found as follows:
The total traffic is 11 E. In the column of 0.5% GOS, the next higher value of 11 E is 14.2 E,
resulting in 3 base stations. The system shall be equipped with 3 base stations, offering the
client 14.4 E instead of 11. This means that the system has an over-capacity 3.2 E, which allows
expansion of the system with 16 cordless phones without reducing the grade of service or the
need of more base stations.

Traffic capacity of the base stations

The total traffic that all cordless phones on a system generate must comply with the capacity of
the cordless network. A base station with 8 channels has an erlang value of 2.7 and a GOS of
0.5%. See the table to read the value. This means that each base station can serve 18 cordless
phones, assuming that each cordless phones generates 150 mE during busy hours and 13.5
cordless phones if each phone generates 200 mE.
Example:
Referring to the building of the customer in the example
page 55, you can achieve full coverage by 4 base stations. This means that all cordless phones
generate together 55 x 0.200 = 11 E, while the base stations traffic capacity is only 4 x 2.7 =
10.8 erlang. The erlang value falls below requirement. This discrepancy can be solved by
adding another base station nearby the busiest part of the company.
From an average usage point of view, the total capacity that the cordless network offers might
be adequate. In certain locations in a building however, traffic demands may vary at different
times of the day. At such times, users experience network blocking, or the network has a lower
GOS than required. For instance, a purchase department might generate 300 mE per cordless
phone during peak hour, when usage by six personnel generates a high load on the closest
base station. You must add a base station in this area to provide adequate capacity for calls by
other personnel. Also factor in the fluctuation in traffic generated in specific areas during
specific time of the day, for example, a canteen during lunch time.
56
Avaya DECT R4 - Installation and Maintenance Guide
Figure 5.
Minutes per hour
3
6
9
12
mE Minutes per hour
250 15
300 18
500 30
750 45
Traffic capacity of the system on
02/2016