Example Uplink Cell Loading for Voice Service

In this
example, we calculate the cell loading as a function of the number of users
assuming that all users are using standard voice service.
Assumptions
aj  0.65
Rj  12.2 Kbps
Eb/No  4 dB( 2.512) for all users (because all users are voice-only in
this example).
i  50% (that is, of the total interference at the base station, one third is
being received from other cells).
Using Equation 12-10, we calculate the uplink load factor for a single
user.
Load factor for one voice user  0.00774  0.774%
Thus, for a load factor of 50 percent, we can accommodate approximately
65 simultaneous voice users. For a load factor of 60 percent, we can accommodate
approximately 76 simultaneous voice users, and so on. The number
of users as a function of load factor (and required interference margin) is
shown in Figure 12-4.
Given that the required interference margin (that is, noise rise) means a
smaller allowable path loss, it is clear that the cell footprint reduces as the
number of users increases. If we consider the link budget shown in Table
12-1 and consider the required interference margin as a function of the
number of users, the allowable path loss (which determines the cell size) is
as shown in Figure 12-5.We should also note that the maximum path loss
shown does not consider building or vehicle penetration losses, which would
need to be subtracted from the figures shown.
The calculation we have performed previously provides the loading in
terms of number of users. We could easily present the loading results in
terms of Kbps. In fact, if we consider that there will be both data and voice
usage, then presenting the information in terms of Kbps can be useful as
that term will apply both to voice and data.