Consider two different cellular systems that share the following characteristics
ID: 3710164 • Letter: C
Question
Consider two different cellular systems that share the following characteristics. The frequency bands are 825 to 845MHz for mobile unit transmission and 870 to 890 MHz for base station transmission. A duplex circuit consists of one 30 - kHz channel in each direction. The systems are distinguished by the reuse factor, which is 4 and 12 respectively.
a) Find the number of simultaneous communications that can be supported by a single cell in each system.
b) Suppose the cell size is the same in both systems and a fixed area of 100 cells is covered by each system. What is the number of simultaneous communication that can be supported by each system?
Explanation / Answer
(a)
Bandwidth assigned to the cluster
Bcl=(845-825)-(890-870)
= 20 + 20
= 40MHz
Required bandwidth for each one-way direction of channel = 30 kHz
Required bandwidth for each two-way direction of channel
Bch=2×30
= 60 kHz
Total number of simultaneous calls thats supports 4 system
Ksys=MBcl/Bch
=4×40/60
=2.66 channels
Total number of simultaneous calls thats supports 12 system
Ksys=MBcl/Bch
=12×40/60
=8 channels
(B)
system with n=4
channels=2.66 channels
number of simultaneous calls=2.66 x 100
=266
system with n=12
channels=8 channels
number of simultaneous calls=8 x 100
=800