An urban area has a population of two million residents. Three competing trunked mobile network (systems A, B and C) provide cellular service in this area. System A has 394 cells with 19 channels each. System B has 98 cells with 57 channels each; and system C has 49 cells each with 100 channels. Find the number of users that can be supported at 2% blocking if each user averages two calls per hour at an average call duration of 3 minutes. Assuming that all three trunked systems are operating at maximum capacity, compute the percentage market penetration of each cellular service provided (Data: GOS = 0.02 Number Of Channels Total Traffic Intensity (Erlangs) 57 45 19 12 100 88

Subject: Mobile Communication

Topic: Cellular Communication System

Difficulty: High

System A

Given: Probability of blocking= 2% = 0.02

Number of channels per cell used in the system, C = 19 Traffic intensity per user, = = 2 × (3/60) = 0.1 .

For = 0.02 and = 19, from the chart, the total carried traffic, A, is obtained as 12 Erlangs.

Therefore, the number of users that can be supported per cell is = / = 12/0.1 = 120

Since there are 394 cells, the total number of subscribers that can be supported by System A is equal to 120 × 394 = 47280.

System B

Given: Probability of blocking= 2% = 0.02.

No. of channels per cell used in the system, = 57. Traffic intensity per user,

= = 2 × (3/60) = 0.1 .

For = 0.02 and = 57, from the chart the total earned traffic, , is obtained as 45 Erlangs.

Therefore, the number of users that can be supported per cell is = / = 45/0.1 = 450

Since there are 98 cells, the total number of subscribers that can be supported by System B is equal to 450 × 98 = 44100

System C Given: Probability of blocking = 2% = 0.02

No. of channels per cell used in the system, C = 100. Traffic intensity per user,

= = 2 × (3/60) = 0.1

For = 0.02 and = 100, from the chart, the total carried traffic, A, is obtained as 88 Erlangs. Therefore, the number of users that can be supported per cell is

= / = 88/0.1 = 880

Since there are 49 cells, the total number of subscribers that can be supported by System is equal to 880 × 49 = 43120

Therefore, total number of cellular subscribers that can be supported by these three systems are 47280 + 44100 + 43120 = 134500 .

Since there are 2 million residents in the given urban area and the total number of cellular subscribers in System A is equal to 47280, the percentage market penetration is equal to: 47280/2000000 = 2.36%

Similarly, market penetration of System B is equal to

44100/2000000 = 2.205%

And the market penetration of System C is equal to

43120/2000000 = 2.156%

The market penetration of the three systems combined is equal to 134500/2000000 = 6.725%.