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In a GSM system, 8 channels can coexist in 200 kHz bandwidth using TDMA. A GSM-based cellular operator is allocated 5 MHz bandwidth. Assuming a frequency reuse factor of \(1/5\), i.e. a five-cell repeat pattern, the maximum number of simultaneous channels that can exist in one cell is

1. 200
2. 40
3. 25
4. 5

Correct answer: 40

Solution

A 5 MHz allocation contains \(5\text{ MHz}/200\text{ kHz}=25\) GSM carriers. Since each carrier supports 8 channels, the total is \(25\times 8=200\) channels over the whole cluster. With reuse factor \(1/5\), one cell gets \(200/5=40\) channels.

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