Specifications

Interface Protocols
Operating Characteristics
3-12 68P81095E55-E August 08, 2000
Frequency Re-use
The system designer selects the reuse pattern during the design process to address
traffic, coverage and frequency requirements.
The iDEN system supports 12-cell/omni re-use pattern or a 7-cell, 3-sector frequency
re-use pattern.
System design goals may be specified as a ratio of carrier energy to interference and
noise energy. Optimal Dispatch call performance is obtained when the Carrier to
Noise plus Interference ratio over 90% of the coverage area is:
For Interconnect calls the ratio over 90% of the coverage area should be:
This ratio is a prime factor in RF design and frequency reuse planning. If there is 1
Base Radio per cell:
• a 12 cell/omni pattern requires 12 channel sets of frequencies
• a 7 cell/3 sector pattern requires 21 channel sets of frequencies.
Frequency distribution maps uses 16 color codes to distinguish between frequency
re-use sites. (Refer Appendix A Planning)
The two patterns are graphically depicted in Figure 3-10 and Figure 3-11.
Figure 3-10 12 Cell Omni Re-use Pattern
CNI+()⁄ 18db≥
CNI+()⁄ 20db≥
11
b
2
a
1
a
5
a
4
a
3
a
12
a
11
a
6
b
8
b
7
b
1
b
2
b
N
R
D
×= 3
D = distance
R= radius of contour
N = Number of cells in reuse pattern (12)
Frequencies used in a cell (pattern-a) can be
used in patterns-b & c if distance formula is met.
6
a
7
a
8
a
9
a
10
a
9
b
10
b
3
b
4
b
5
b
12
b
11
c
6
c
7
c
5
c
2
c
1
c
4
c
3
c
8
c
9
c
10
c
12
c