10-10-2012, 05:32 PM
An Implementation of Wireless Sensor Network for Security System using Bluetooth
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Abstract
In recent years, the advances in wireless
communication and electronics have accelerated to develop
many wireless network solutions to replace existing wired
networks. A wireless network solution can support mobility
and flexibility of nodes in a network. Especially in sensor
networks, it has many advantages to replace cables with
wireless logical links. On the other hand, Bluetooth is
generally considered as a promising short-range wireless
technology because of its inexpensive cost, low power and
small size, and thus Bluetooth has been gaining increasing
interest from various industries. For the above reasons, we
adopt Bluetooth technology for a wireless sensor network
which is designed for security systems. Since Bluetooth will
continue to be a feature found in many devices, it is
worthwhile to investigate its use in wireless sensor networks.
In this paper, we describe a Bluetooth wireless sensor network
for security systems, which includes the implementation issues
about system architecture, power management, selfconfiguration
of network, and routing. We think that the
methods or algorithms described in this paper can be easily
applied to other embedded Bluetooth applications for wireless
networks.
INTRODUCTION
Bluetooth uses short-range radio links, intended to
replace the cables connecting portable and/or fixed electronic
devices [1]. It is envisaged that it will allow for the
replacement of many propriety cables that connect one device
to another with one universal radio link. Its key features are
robustness, low complexity, low power and low cost.
Designed to operate in noisy frequency environments, the
Bluetooth radio uses a fast acknowledgement and frequency
hopping scheme to make the link robust. Bluetooth radio
modules operate in the unlicensed ISM (Industrial, Scientific
and Medical) frequency band at 2.4GHz, and avoid
interference from other signals by hopping to a new frequency
after transmitting or receiving a packet. Compared with other
systems in the same frequency band, the Bluetooth radio hops
faster and uses shorter packets. In this paper, we introduce a
system implementation of a wireless sensor network for
security systems using Bluetooth.
THE PROPOSED SYSTEM ARCHITECTURE
In this section, we give a full explanation about the
proposed system. To help understand the system operation, we
first introduce an overall working flow of the system and then
explain the initialization procedure for network configuration
and routing. Finally, we introduce the operation of each node
in the system in more detail.
System Overview
The purpose of the proposed system is for detecting an
invasion in a building that needs security service, and it
consists of lots of sensor and relay nodes and a control node.
Figure 5 illustrates the communication environment of the
system. Sensor nodes are placed in each room in the building
and logically connected to the control node, which is located
at a certain place in the building and can be reached via relay
nodes.
Network Configuration
It is common that sensor and relay nodes are not able to
directly communicate with the control node. Thus network
configuration is required for routing packets over the multihop
route and maintenance of nodes, but which is performed
not by a manual setting but by a self-configuration. As
previously explained in Section 1, the tree topology as shown
in Fig. 7 is used for network configuration in the proposed
system. The tree topology has many advantages in that it is
easy to find a multi-hop route to the control node or a specific
node, to maintain network structure, and to control medium
access and transmission timing.
On the other hand, each Bluetooth device is allocated a
unique 48-bit Bluetooth device address (BD_ADDR). This
address is derived from the IEEE802 standard. With this
address, Bluetooth transceivers can communicate with each
other in only one hop range. In addition to the BD_ADDR, we
define a logical address such as IP address for finding multihop
routes easily in networks with tree topology.
CONCLUSION AND FURTHER WORK
We have proposed a wireless sensor network for security
systems using Bluetooth technology. We have introduced its
system architecture, power management, self-configuration of
network and routing. In this paper, the tree topology has been
used for network configuration and routing since it can be
considered as a natural and appropriate choice for Bluetooth
networks. Thus routing is an easy matter in the proposed
network. Also, it can give many advantages from the
viewpoint of network maintenance, controlling medium access.
Also, we have developed application programs for the nodes
which can directly drive their Bluetooth module through the
HCI interface without the help of the upper layer protocols.
Instead, the basic functions of the eliminated upper layer
protocols are implemented in the application program. By
doing so, we can fully use the limited processing power and
memory of the ARM CPU core in the Bluetooth Host
Controller.