Skip to content

WSN

Metrics

Energy consumption metrics

  • Duty Cycle: The ratio of time a node is active versus the time it is in sleep mode.
  • Average Energy Consumption: The total energy consumed by all nodes divided by the number of nodes over a specific period.
  • Energy per Successful Data Packet: The total energy spent (including overhead, retransmissions, and idle listening) to deliver one unit of payload.
  • Residual Energy: The remaining battery power in each node. This helps identify "hotspots" where nodes are dying faster than others.

Network lifetime metrics

  • First Node Dead (FND): The time elapsed until the first sensor node runs out of energy.
  • Half of Nodes Alive (HNA): The time until 50% of the nodes have depleted their batteries.
  • Last Node Dead (LND): The time until the entire network becomes non-functional.
  • Sensing Coverage Lifetime: The duration for which the network can monitor a specific percentage of the target area.

Reliability and Quality of Service (QoS)

  • Packet Delivery Ratio (PDR): The ratio of packets successfully received by the sink (gateway) to the total packets sent by the source nodes.
  • Packet Loss Rate: The percentage of packets dropped due to collisions, interference, or buffer overflows.
  • Bit Error Rate (BER): The number of bit errors divided by the total number of transferred bits during a studied time interval.
  • Throughput: The amount of data successfully moved from source to destination in a given time, usually measured in bits per second (bps).

Temporal Metrics (Latency)

  • End-to-End (E2E) Delay: The time taken for a packet to travel from the sensing node to the sink. This includes queuing, processing, and transmission delays.
  • Jitter: The variation in the delay of received packets. High jitter can be problematic for real-time monitoring.
  • Settling Time: The time required for the network to become fully operational after deployment or a major topology change.
  • Age of Information (AoI): This is currently a high-impact metric in research. It measures the "freshness" of the data at the receiver. Unlike delay, which starts when a packet is sent, AoI increases until a new update is received.

Topological and Spatial Metrics

  • Sensing Coverage: The fraction of the target area monitored by at least one sensor node.
  • Connectivity: The ability of nodes to reach the sink through single or multi-hop paths.
  • Node Density: The number of nodes per unit area. Higher density can improve reliability but increases the risk of signal collisions.
  • Network Scalability: A measure of how the PDR and Latency are affected as the number of nodes increases from tens to thousands.