A. Opportunistic Wi-Fi through vehicular node
First, we study the raw throughput gains that can be achieved by vehicular nodes when they opportunistically use Wi-Fi hotspots while already being connected to an LTE
network.
In the simulation, a multihomed mobile client moves along a straight road at varying speeds, with access points deployed along the road at random inter-AP distances d.
The values for d are chosen from a uniform distribution between 300-500 meters, and thus, the mobile node experiences varying connectivity, as well as temporary disconnections through Wi-Fi.
The LTE connection is simulated to have a stable coverage but with lower achievable data rate, as is prevalent in typical vehicular scenarios.
The number of hops from the server to the client is kept at 4, however, the link delay
from the core to the edge is set to 10ms to have a realistic network model.
Fig. 4 shows the aggregate throughput at the client, when it receives a continuous stream of data for the entire simulation, along with the transfer completion times
when the client requests a single file of random size between 60-80 MBytes.
Three sets of experiments were performed:single-homed over Wi-Fi, single-homed over LTE, and dualhomed with simultaneous transfer over both the interfaces.
Each set was averaged over 10 runs. As the figures indicate,the in-network data-striping algorithm fully utilizes the WiFi interface whenever it becomes available.
This is indicated by the multihoming throughput being close to the sum of the
throughputs achievable through individual interfaces.