WaveRider LMS4000, User Manual

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5 Radio Network Planning
68 APCD-LM043-4.0
information). Throughout this manual, however, WaveRider has referred to the standard
frequency set shown in
Table 11 .
Table 11 Standard Frequency Set
The standard frequency set represents a convenient and safe set of frequency assignments.
The frequencies are orthogonal in that they do not overlap, and they provide enough
separation between the frequencies so that one channel does not interfere with either of the
other channels, even if they are installed at the same CAP site with appropriate filters. Using
the standard frequency set, you can implement small systems without much concern for self-
generated interference.
In the case of a multi-CAP network, however, the standard frequency set may not be
inadequate. Instead, you must use other sets of frequencies at neighboring CAP sites. The
selection of these other frequency sets is governed largely by the minimum C/I requirement for
the CCU and EUM radio; i.e., the amount of interference, from within or from outside the
system, that the LMS4000 radio equipment can tolerate.
5.3.3 C/I Requirements
The CCU/EUM C/I requirements are outlined in Table 12 .
Table 12 Required C/I Ratio for Multi-CAP Design
As shown in Table 12 , as the frequency separation between the desired LMS4000 signal and
an interfering LMS4000 signal increases, the level of an interfering signal that can be tolerated
also increases. Consider the case where the frequency separation between the desired
channel and an interfering channel from a remote site is 0.2 MHz. To maintain a packet error
rate of 1% in the local cell, you would need to ensure that the EUMs in the local cell are
receiving the desired CCU signal at a level which is at least 22 dB higher than the interfering
CCU signal, 0.2MHz away.
Using this information, and information about the number and location of the required CAP
sites, your RF designer should be able to define a frequency plan for your system.
905.0MHz
915.0MHz
925.0MHz
C/I Ratio Frequency Separation PER
22 dB 0.2 MHz < 1%
19 dB 1.6 MHz < 1%
11 dB 3.4 MHz < 1%