In this routing switching process, routing information interaction among sensor nodes is unnecessary since each sensor node can choose the efficient dissemination direction independently according to the beacon signal from mobile gateway.
Using the conversion algorithm, routing table of node #0 is calculated and shown in Figure 4. From the new routing table, each sensor node can decide the dissemination direction according to the priority and set of beacon cluster activated by the UE.
To quantify the correlation between wind direction and cholera spatial dissemination pattern for Vibrio cholerae dissemination in Africa during 1970 1971, we used the formula for circular correlation (ρ circ) of Jammalamadaka and SenGupta (2001): This formula denotes the sample pairs of directions (wind direction and the cholera spatial dissemination direction).
Store-carry-forward: to cope with disconnected sparse networks, vehicles that are furthest away in one of the dissemination directions assume the responsibility of carrying, storing, and rebroadcasting the messages received forward to new vehicles that are encountered.
With these measures, we guarantee the message dissemination in each possible direction while minimizing the delay and number of transmissions.
To achieve this goal, we focus on the following aspects: Adaptive multi-directional dissemination: to achieve an efficient wide-spreading data dissemination, each data message is simultaneously disseminated to multiple directions that are adaptively adjusted according to the local map of the road provided, for example, by a GPS navigation system.
On one hand, highways are most commonly addressed with a single directional dissemination, as the data generated is assumed to only affect vehicles in one road direction, e.g., upon the event of an accident.
Adaptive multi-directional dissemination: to achieve an efficient wide-spreading data dissemination, each data message is simultaneously disseminated to multiple directions that are adaptively adjusted according to the local map of the road provided, for example, by a GPS navigation system.
This paper brings out current research efforts on information management techniques employed for safety related applications in VANETs, which includes gathering, aggregation, validation and dissemination, and also provide directions for future research and development.
In order to accurately define the directions of dissemination, we assume that a vehicle is equipped with a device that provides road mapping information, such as a GPS navigation system.
On the other hand, choosing an excessive low number of sectors may lead to the suppression of transmissions of vehicles driving in potential road directions of dissemination, thereby causing higher delays and lower delivery ratio.
