Research Article

Transmission Opportunities: A New Approach to Improve Quality in V2V Networks

Table 2

Summary of forwarding protocols’ performance evaluation metrics.

MetricDescriptionBenchmark unit

Created messages (CM)Total number of created messages. Do not include replication.Number
Relayed messages (RM)Total number of successful transmissions between nodes.Number
Aborted messages (AM) and packet lossTotal number of transmissions messages that fail before finished. Aborted messages occur due to disconnection during the transmission between nodes.Number
Started messages (SM)Total number of transmissions started. SM = (RM) + (AM).Number
Dropped messagesTotal number of dropped messages from nodes buffers before delivery to final destination.Number
Delivered messages (DM) or number of messagesTotal number of successful delivered messages in final target.Number
Messages delivery ratio (MDR)Messages delivery probability. MDR = ((1.0  DM)/CM).Percentage (%)
Overhead ratio (OR)An assessment of bandwidth efficiency. It is the number of created copies per delivered message. It amounts the number of replicas necessary to perform a successful delivery.Percentage (%) number
Latency averageLatency average messages delay from creation to delivery.Seconds
Hop count averageAverage number of hops between source and destination.Number
Buffer time averageAverage time that messages stay in the buffer at each node.Number
Buffer size occupancyBuffer size occupancy average at each node.Bytes
RTT averageRound-trip time average. Average time from creation to confirmation of delivery.Seconds
End-to-end delayTime taken for a message transmission across a network from source to destination.Seconds
ThroughputThe number of transactions per second an application can handle, the amount of transactions produced over time during a test.Transactions per second
Link failureThe period of consecutive packet loss that can last for many seconds, followed by a change in delay after the link is reestablished.Seconds
Transmission opportunity (TOpp)The ratio between the total amounts of resources that a protocol could have to the actual number of resources used by this protocol. This metric can evaluate the resource consumption such as the number of transmission opportunities, contact time duration, or data transfer in the network.Percentage (%) time (seconds); data stream (Mbps)