Information Technology Reference
In-Depth Information
Synchronisation: It is in charge of asynchronous information retrieval from
different sources. One of the principal problems lies in synchronising asyn-
chronous information. For this the mechanism known as “time window” is used
which establishes a time margin for retrieving the information before it is pro-
cessed. In these time windows “time baskets” are in turn established where the
labelled Events are stored with the same timestamp. A time window may have
two or more time baskets. Both the time window time space and the number
of time baskets are determined by the system requirements. Figure 4 shows an
example of the time windows N and N+1. In the time window N, two time
baskets are established for timestamps t and t+1. The events that arrive in the
time window N are automatically classified into each of the time baskets with
the timestamp that each of the received events has. When the time window N
finishes, the time window N+1 is created and the timestamp t time basket is
processed.
This process is necessary because the events with different timestamps are
interspersed when they are received. This is due to communication and time
delay factors in the information processing in each of the Remote Nodes. For
example, the system can receive the following sequence of events in the time
window N:
Fig. 4. Time windows and time baskets
The time space of the time window has to be wide enough to retrieve all
the events with the same timestamp. As shown in the Formula (formula) this
process is done considering the maximum processing time of a Remote Node, the
communication delay and adding a security margin. This mechanism guarantees
the reception of all the events with the same timestamp before they are processed.
TimeWindow
(
ms
)=
MaximumProcessingT imeOfARemoteNode
(
ms
)+
EstimatedMaximumComunicationDelay
(
ms
)+
SecurityMargin
(
ms
)
Standardisation: The identification process of each of the Remote Nodes pro-
vides different labels for each of the scene objects. This generates inconsistent
names for the same objects perceived by different Remote Nodes. To solve this
 
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