3.3 Frequency Planning Principle
Generally, when planning the frequency for the network, you will divide the geographic area into smaller slices, but you must reserve a certain amount of channel number at the intersection area between slices if the frequency resource is adequate.
The intersection area must be far away from the areas where the traffic is great and the areas where the networking is complex. Generally, you should begin the planning with the area where base stations are intensively distributed. If there are rivers or big lakes in the planning area, you must consider the refection effect of the surface.
Generally, base stations irregularly distributed, so you cannot perform the frequency planning completely according to 4 x 3 frequency reuse pattern or 3 x 3 frequency reuse pattern. Instead, you must make flexible adjustment according to actual conditions.
No matter which reuse pattern you take, you must obey the following principles:
- Generally, the intra-frequencies and adjacent cannel numbers are allowed to appear within a base station.
- The frequency spacing between the BCCH and TCH must be greater than 400 KHz within a cell.
- The frequency spacing between the TCHs must be greater than 400 KHz within a cell. (When frequency hopping is used, you can meet this by properly setting the mobile allocation index offset.)
- The adjacent base stations cannot use the same frequency.
- Considering the complexity of the antenna height and radio propagation environment, the base stations near each other cannot use the same frequency.
- Generally, if using the 1 x 3 frequency reuse pattern, you must ensure that the number of frequency hopping channel numbers is at least twice that of the frequency hoping carriers.
- Pay special attention to the intra-frequency reuse. The adjacent areas are not allowed to share the BCCH and the BSIC.

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