Sample Exams Questions and Answers on Computer Networks
CCM 4300 Lecture
Computer Networks, Wireless and Mobile Communication Systems
SAMPLE EXAM QUESTIONS
Dr P. Shah
1
Show that, according to the Shannon-Hartley law, if the signal power (S) is equal to the noise power (N), the channel capacity (C) in b/s is equal to the bandwidth B Hz. (6 marks)
C= B log2 (1+S/N) If S=N C=B log2 (1+1) C=B log2 (1+1) C= B log2 (2) C=B
2
What are the purposes of the following GSM networks? VLR HLR MSC (home and visited) (6 marks) VLR: it is a database maintained by the visited network that contains an entry for each mobile user that is currently in the portion of the network served by VLR. HLR: a database that is maintained by the home network which contains permanent cell phone number and subscriber profile information for each of its subscribers. It also contains information about the current location of those mobile nodes under its care. Home MSc: point of contact to obtain routable address of mobile users. Visited MSC: is responsible for setting up calls to/from mobile nodes in cells associated with MSC.
For Bluetooth based networking, state the three power saving mechanisms and discuss their negative effects on the transmission QoS. (8 marks) Active Mode, Sniff mode, Hold mode, and Park mode. All systems save power by periodic sleep functions. In particular Bluetooth systems, which offer several low power modes, as they are typically, battery operated. Negative effects of power saving are the increased latency for spontaneous transmission – the devices have to wakeup first. Thus, the shorter access delay should be less power a device can save. Furthermore, high data rates require high power. If the periodic sleep function is not synchronised with i.e., periodic data transfer, heavy jitter will result
What are the different types of cells in a GSM cell structure and where are they used? (7marks)
Different types of cells in a GSM cell structure and their specific uses are as below: 1. Hot spots – Cell within
Computer Networks, Wireless and Mobile Communication Systems
SAMPLE EXAM QUESTIONS
Dr P. Shah
1
Show that, according to the Shannon-Hartley law, if the signal power (S) is equal to the noise power (N), the channel capacity (C) in b/s is equal to the bandwidth B Hz. (6 marks)
C= B log2 (1+S/N) If S=N C=B log2 (1+1) C=B log2 (1+1) C= B log2 (2) C=B
2
What are the purposes of the following GSM networks? VLR HLR MSC (home and visited) (6 marks) VLR: it is a database maintained by the visited network that contains an entry for each mobile user that is currently in the portion of the network served by VLR. HLR: a database that is maintained by the home network which contains permanent cell phone number and subscriber profile information for each of its subscribers. It also contains information about the current location of those mobile nodes under its care. Home MSc: point of contact to obtain routable address of mobile users. Visited MSC: is responsible for setting up calls to/from mobile nodes in cells associated with MSC.
For Bluetooth based networking, state the three power saving mechanisms and discuss their negative effects on the transmission QoS. (8 marks) Active Mode, Sniff mode, Hold mode, and Park mode. All systems save power by periodic sleep functions. In particular Bluetooth systems, which offer several low power modes, as they are typically, battery operated. Negative effects of power saving are the increased latency for spontaneous transmission – the devices have to wakeup first. Thus, the shorter access delay should be less power a device can save. Furthermore, high data rates require high power. If the periodic sleep function is not synchronised with i.e., periodic data transfer, heavy jitter will result
What are the different types of cells in a GSM cell structure and where are they used? (7marks)
Different types of cells in a GSM cell structure and their specific uses are as below: 1. Hot spots – Cell within