wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

11-10 Industrial Communication Systems
11.6 WMSNs’ Technical Challenges
WMSN is a cross-disciplinary research area that involves communication, signal processing, embedded
computing, and control theory. Since most of the information in WMSNs is related to multimedia, there
are a number of factors that influence the design of WMSN and are described in this section.
11.6.1 WMSN Application-Specific QoS Requirement
WMSNs must support application-specific QoS requirements. WMSNs are designed to address a range
of applications from simple data transfer as in case of scalar networks to multimedia communication.
The multimedia information may be a snapshot of an event or a streaming multimedia content. The
streaming multimedia content communication requires high bandwidth and is delay sensitive. Also,
the streaming multimedia information is generated over longer time periods, as opposed to snapshot
multimedia information that contains event-triggered observations obtained over a short period of
time, and is to be conveyed reliably. So the high-level WMSN multimedia algorithms and underlying
WMSN hardware should have strong linkage so as to support application-specific QoS requirements,
keeping in view the delay, energy consumption, reliability, and network lifetime constraints of WMSNs.
11.6.2 Scalable and Flexible Architectures and Protocols
to Support Heterogeneous Applications
The WMSN design should be flexible enough for the network expansion and support various independent
and heterogeneous applications. So while designing WMSN, it is of key importance that the underlying
WMSN-embedded design and protocol suite must support the heterogeneous applications up to
their required QoS specifications while ensuring the reliability, privacy, delay, and energy constraints
as well.
11.6.3 High Bandwidth
Existing WSN architecture that supports scalar data communication requires less bandwidth as compared
to WMSN architecture, where the data is video stream by nature requiring large bandwidth and is
highly delay sensitive. In WMSN, hop-by-hop routing nature, the node not only sends its own multimedia
information (either snapshot of an event or streaming multimedia contents) but also the multimedia
and scalar data information from the child nodes as well. So the parent node must have large throughput
to support the large bandwidth requirement of multimedia information. The existing WSN nodes that
support 802.15.4 standard (MICAz, TelosB, etc.) have maximum capability of 250 kbps, but in the case
of WMSN application, we may require a bandwidth order of magnitude higher than this ultra-wideband
(UWB), or impulse radio technologies are considered as promising communication technologies to provide
high bandwidth capacity to existing WMSN applications.
11.6.4 Localized Processing and Data Fusion
In WMSN, each node gathers information (multimedia by nature) from surroundings and from child
nodes (hop-by-hop network topology). Most of the data are unprocessed or raw in nature [GGC01], carrying
too much redundant information, which requires high bandwidth. So the concept of in-network
or localized processing was introduced to overcome the effects of raw data transmission. In case of innetwork
processing, the gathered information is processed locally at the node side prior to transmission
to the parent node, e.g., data of the same event taken by multiple video sensors may need to be filtered
to reduce the repeated information; in video security application, the information from the interesting
scenes can be compressed to a simple scalar value; and so on. However, the traditional video/audio
© 2011 by Taylor and Francis Group, LLC