JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV WIRELESS SENSOR NETWORKS Previous Question Paper (July/August - 2022 - R18)

A Wireless Sensor Network (WSN) is a spatially distributed network of autonomous, low-power sensor nodes that cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, or motion. These nodes collect data, process it locally, and transmit it wirelessly to a base station or sink node for further analysis.

WSNs differ from conventional wireless networks (like Wi-Fi or Cellular networks) in the following ways:

• Resource Constraints: WSN nodes have limited battery power, memory, and processing capability, whereas conventional nodes are typically mains-powered with significant computational resources.
• Network Topology: WSNs often utilize ad-hoc, multi-hop mesh topologies to conserve energy, while conventional networks usually rely on fixed infrastructure (access points or base stations).
• Data Traffic Pattern: WSNs are data-centric, where nodes report sensed information to a sink. Conventional networks are address-centric, focusing on point-to-point communication between identified users.
• Scalability and Deployment: WSNs often involve thousands of densely deployed nodes in harsh environments, whereas conventional networks involve fewer, more robust devices in controlled settings.

In military applications, WSNs are deployed for battlefield surveillance, target tracking, and perimeter security. The architecture consists of sensor nodes deployed across a region, which communicate via a multi-hop wireless link to a local cluster head, which then forwards data to a command center via satellite or long-range radio.

The architectural flow is represented as: [Sensor Nodes] → [Cluster Head] → [Gateway/Sink] → [Command & Control Center].

Key military use cases include:

• Battlefield Surveillance: Deploying acoustic and seismic sensors to detect enemy troop movements or vehicle activity in real-time.
• Nuclear, Biological, and Chemical (NBC) Detection: Rapidly deploying sensors to identify hazardous materials in an area before sending personnel.
• Intrusion Detection: Monitoring perimeters or borders for unauthorized access, providing early warning systems that are difficult for adversaries to detect or jam compared to traditional surveillance.