Mobile and Pervasive Computing in Construction: an Introduction - Mobile and Pervasive Computing in Construction - page 6

Models (BIM) have much potential to be located in file servers to be downloadable.
The client sends an inquiry to the server and then waits for responses. Then
the server sends the requested data as a response to the client. In this process,
apparently both the computing power and the wireless bandwidth are
consumed. More resources will be occupied and consumed if a large number of
clients access the server and the size of data transferred is large as well. This is a
very typical phenomenon in a construction site, where you have many different
types of mobile personnel working on different activities. All have to access
different types of information from the server and usually the information
needed is large.
1.2.4 Sensor networks
Wireless networks of smart sensors have become feasible for many applications
because of technological advances in semiconductors, energy efficient wireless
communication and reduced power budgets for computational devices, as well as
the development of novel sensing materials (Akyildiz et al., 2002). The following are
the common properties of the sensor networks:
* Sensor nodes are usually designed to directly interact with the physical world
and to perform computational tasks based on the confirmation gathered from
the surrounding environment (Estrin et al., 2001).
* Usually they are special purpose devices, such as biological sensors, thermal
sensors, acoustic sensors vibration sensors, light sensors, chemical sensors and
magnetic sensors.
* It becomes a special challenge that there usually are very limited resources in
wireless computing which have limited communication bandwidth. These
resources have to be shared among numerous sensors.
* There needs to be a specialized routing pattern to enable the communication
to occur between sensors at adjacent levels.
1.2.5 Security
Security is a critical issue in mobile computing as it concerns the interested parties
using the technology. There are different aspects of security in mobile computing.
There are four common security issues (Schneier, 1996):
(i) System integrity or data integrity: a systemprovides integrity if it performs its
intended function in an unimpaired manner, free from deliberate or
inadvertent unauthorized manipulation of the system.
(ii) Confidentiality: data are provided when only intended recipients can read
the data.
(iii) Nonrepudiation: it is a property of data and means that the sender should
not be able to falsely deny sending the data. This property is important for
e-bidding in construction procurement, because owners do not want con-
tractors or subcontractors to be able to deny that they had bid with a price.