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

Industrial Strength Wireless Multimedia Sensor Network Technology 11-7
transfer, a complex programmable logic device (CPLD) is used to provide access to the high-speed
clock. However, it can be better addressed by using single FPGA.
Researchers at Carnegie Mellon University are developing the CMUcam 3 [CMU08], which is an
embedded camera endowed with a CIF Resolution (352 × 288) red green blue (RGB) color sensor that
can load images into memory at 26 frames per second. The CMUcam 3 is not equipped with onboard
networking capabilities, but an external mote can be attached via a serial communication channel.
CMUcam 3 has software JPEG compression and has a basic image manipulation library, and can be
interfaced with an 802.15.4 compliant TelosB mote [TB08].
Another integrated imaging mote was proposed [DRA06] that comprised ARM7 32 bit CPU clocked
at 48.MHz with external flash storage, 802.15.4 complaint CC2420 radio chip, ADCM-1670 (CMOS sensor),
and CIF (low-resolution 30 × 30 pixel optical sensor). The 32 bit ARM7 is used in this case for reasons
of energy constrain as it would take a shorter time to process various image processing algorithms
as compared to the traditionally used 8 bit architecture (Atmel’s ATmega128 in WSN).
11.4.2 Medium-Resolution WMSN Motes
The Stargate board [SP08], designed by Intel and produced by Crossbow, is an example of mediumresolution
imaging (WMSN) mote when combined with a Logitech webcam. The Stargate board is a
high-performance processing platform despite being designed for sensor, signal processing, control,
robotics, etc. and can also be used in sensor network applications as an independent mote (WMSN
mote when combined with webcam). Stargate is based on Intel’s PXA-255 XScale 400.MHz RISC processor.
It has 32.MB of Flash memory, 64.MB of SDRAM, and an onboard connector for Crossbow’s
MICA2 or MICAz motes as well as PCMCIA Bluetooth or IEEE 802.11 cards. Hence, it can work as a
wireless gateway and as a computational hub for in-network processing algorithms. WMSN mote based
on Stargate platform consumes more energy and is not good from the energy consumption point of
view [MPOM06]. Besides, it has high energy consumption; another drawback of the PXA-255 XScale
processor is that it supports fixed-point computations only. But since the video application demands
floating-point operations, we can use efficient software implementations needed to efficiently perform
multimedia processing algorithms.
Intel has also developed two prototypal generations of wireless sensors, known as Imote and Imote2.
Imote is built around an integrated wireless microcontroller consisting of an 8 bit 12.MHz ARM7 processor,
a Bluetooth radio, 64.KB RAM, and 32.KB FLASH memory, as well as several I/O options. The
software architecture is based on an ARM port of TinyOS. The second generation of Intel motes has a
common core to the next-generation Stargate 2 platform and is built around a new low-power 32 bit
PXA271 XScale processor at 320/416/520.MHz, which enables performing DSP operations for storage
or compression, and an IEEE 802.15.4 ChipCon CC2420 radio. It has a large onboard RAM and Flash
memories (32.MB), additional support for alternate radios, and a variety of high-speed I/O to connect
digital sensors or cameras. Its size is also very limited, 48 × 33.mm, and it can run the Linux operating
system and Java applications.
11.4.3 High-Resolution WMSN Motes
Researchers at BWN laboratory have deployed.an experimental testbed [GT08] based on currently-offthe-shelf
advanced devices to demonstrate the efficiency of their newly developed algorithms and protocols
for multimedia communications through wireless sensor networks. The testbed includes three
different types of multimedia sensors support, i.e., low-end imaging sensors, medium-quality webcambased
multimedia sensors, and high-end pan-tilt cameras. The high-resolution WMSN motes consist
of pan-tilt cameras installed on a robotic platform. The objective is to develop a high-quality mobile
platform that can perform adaptive sampling based on event features detected by low-end motes. The
mobile actor can then redirect high-resolution cameras to a region of interest when events are detected
© 2011 by Taylor and Francis Group, LLC