Endsem (Units 3-6)

Endsem Examination Bank: Unit 3 Section A: GSM Signaling and MAP Outline the layers of the Signaling System No. 7 (SS7) protocol stack used in GSM. Explain the specific role of the Signaling Connection Control Part (SCCP) and Global Title Translation (GTT) when an MSC queries an unknown HLR. The Signaling System No. 7 (SS7) is the critical, out-of-band signaling backbone that governs all call setup, mobility management, and billing in GSM networks. It is physically and logically separated from the voice bearers. ...

Endsem Examination Bank: Unit 4 Section A: Network Layer Mobility (Mobile IP) Explain why traditional IPv4 fails when a mobile node moves to a new subnet. Why does dynamically assigning a new IP address via DHCP break existing TCP connections? Traditional Internet Protocol (IPv4) architecture operates under a fundamental, inflexible assumption: an IP address serves dual, inseparable purposes. First, it acts as a unique endpoint identifier for the device. Second, it acts as a rigid topological locator dictating exactly where that device resides within the global network tree. The network prefix of the IP address must mathematically match the physical subnet where the router is attempting to deliver the packet. If a mobile node physically moves to a new foreign subnet but retains its original Home IP address, the local routers in the foreign network will inspect the packet, realize the network prefix is entirely invalid for their local routing tables, and immediately drop the packet. The node is physically connected, but topologically exiled. ...

Endsem Examination Bank: Unit 5 Section A: Mobile Transport Layer (TCP) Explain why traditional TCP’s congestion control mechanisms (Slow Start, Congestion Avoidance) fail catastrophically in wireless environments. How does a high Bit Error Rate (BER) mimic network congestion to the TCP sender? The Transmission Control Protocol (TCP) was architected in the 1970s for highly reliable, wired fiber-optic and copper networks. In these pristine environments, the physical Bit Error Rate (BER) is infinitesimally small (often less than 10^-9). Consequently, the original designers of TCP made a hardcoded, fundamental assumption: if a packet is lost in transit and fails to generate an Acknowledgment (ACK), it is almost certainly because an intermediate router became overloaded and its memory buffer overflowed. This is the definition of Network Congestion. ...

Endsem Examination Bank: Unit 6 Section A: Multipath Fading Channels Fundamentally contrast the Rayleigh fading model with the Rician fading model regarding the presence of a Line-of-Sight (LOS) path. If the Rician K-factor $K = 0$, what does the Rician Probability Density Function (PDF) reduce to? The fundamental distinction between Rayleigh and Rician fading models lies entirely in the presence or absence of a deterministic, dominant Line-of-Sight (LOS) signal path between the transmitter and the receiver. ...