1. 1. Lost-Call System Objective of simulation will be to process given number of call to determine processed, completed, blocked and busy call. Simulation of Telephone System
2. 2. 1 2 3 4 5 6 7 8 0 1 0 1 1 0 1 0 LINES MAX No. IN USE 3 2 LINK S 102 7 CLOCK 1 7 20 FRO M TO LENGT H 1057 ARRIVAL TIME NEX T CALL 4 7 1075 2 5 1053 FRO M TO END CALLS IN PROGRESS 131 98 5 28 PROCESS ED COMPLETE D BLOCKED BUSY CALL COUNTERS Fig (a) : - System State - 1
3. 3. Fig (a), records the state of the system at time 1027 There are two activities causing events: New calls can arrive Existing calls can finish
4. 4. As shown in fig(a), there are 3 future events: The call between lines 2 and 5 is due to finish at time 1053 The call between lines 4 and 7 is due to finish at time 1075 New call is due to arrive at time 1057
5. 5. First step= scan the next potential event In this case, the next potential event is 1053. The clock is updated. Second step= Select the Activity that is to cause event In this case, the activity is to disconnect the call. Third step= Test whether the potential event can be executed Fourth step= Change records to reflect the effects of the event The call is shown to be disconnected by setting 0 for lines 2 and 5, reducing the number of links in use by 1, and removing the finished call from the call-in-progress table
6. 6. Fifth and final step= Gather statistics of simulation output Counters are set aside to record the number of processed, completed, blocked and busy calls. With the disconnection of a call processed and completed call counts are increased by 1 The state of the system then appears as shown in fig(b)
7. 7. 1 2 3 4 5 6 7 8 0 0 0 1 0 0 1 0 LINES MAX No. IN USE 3 1 LINK S 105 3 CLOCK 1 7 20 FRO M TO LENGT H 1057 ARRIVAL TIME NEX T CALL 4 7 1075 FRO M TO END CALLS IN PROGRESS 132 99 5 28 PROCESS ED COMPLETE D BLOCKED BUSY CALL COUNTERS Fig (b) : - System State - 2
8. 8. 1 2 3 4 5 6 7 8 0 0 0 1 0 0 1 0 LINES MAX No. IN USE 3 1 LINK S 105 7 CLOCK 3 6 98 FRO M TO LENGT H 1063 ARRIVAL TIME NEX T CALL 4 7 1075 FRO M TO END CALLS IN PROGRESS 133 99 5 29 PROCESS ED COMPLETE D BLOCKED BUSY CALL COUNTERS Fig (c) : - System State - 3
9. 9. 1 2 3 4 5 6 7 8 0 0 1 1 0 1 1 0 LINES MAX No. IN USE 3 2 LINK S 106 3 CLOCK 1 5 132 FRO M TO LENGT H 1082 ARRIVAL TIME NEX T CALL 3 6 1161 4 7 1075 FRO M TO END CALLS IN PROGRESS 133 99 5 29 PROCESS ED COMPLETE D BLOCKED BUSY CALL COUNTERS Fig (d) : - System State - 4
10. 10. Typically, the simulation will run until a given number of calls has been processed or certain time has elapsed
11. 11. Delayed Calls Telephone system modified so that call which is not connected are not lost Instead they wait until they are connected Happens to messages in switching system that has store and forward capability
12. 12. 1 2 3 4 5 6 7 8 0 0 0 1 0 0 1 0 LINES MAX No. IN USE 3 1 LINK S 105 7 CLOCK 3 6 98 FRO M TO LENGT H 1063 ARRIVAL TIME NEX T CALL 4 7 1075 FRO M TO END CALLS IN PROGRESS 132 99 5 29 PROCESS ED COMPLETE D BLOCKED BUSY CALL COUNTERS Fig (e) : - System State 3A 1 7 20 FRO M TO LENGT H DELAYED CALLS
13. 13. System moves through the first 2 states exactly as before State of the system at time 1057, when the call from line 1 has arrived, now appears as shown in fig(e), which is labelled as system state-3A Same as state 3, shown in fig(c), except that it now shows the delayed call When a call is completed, it is necessary to check the delayed call list to see if a waiting call can be connected The next event, however is arrival of call from line 3 at time 1063 which is going to line 6. The
14. 14. 1 2 3 4 5 6 7 8 0 0 1 1 0 1 1 0 LINES MAX No. IN USE 3 2 LINK S 106 3 CLOCK 1 5 132 FRO M TO LENGT H 1082 ARRIVAL TIME NEX T CALL 3 6 1161 4 7 1075 FRO M TO END CALLS IN PROGRESS 132 99 5 29 PROCESS ED COMPLETE D BLOCKED BUSY CALL COUNTERS Fig (f) : - System State 4A 1 7 20 FRO M TO LENGT H DELAYED CALLS
15. 15. 1 2 3 4 5 6 7 8 1 0 1 0 0 1 1 0 LINES MAX No. IN USE 3 2 LINK S 107 5 CLOCK 1 5 132 FRO M TO LENGT H 1082 ARRIVAL TIME NEX T CALL 3 6 1161 1 7 1097 FRO M TO END CALLS IN PROGRESS 133 100 5 29 PROCESS ED COMPLETE D BLOCKED BUSY CALL COUNTERS Fig (g) : - System State 5A FRO M TO LENGT H DELAYED CALLS
16. 16. Thankyou!