26-04-2012, 11:42 AM
A Smart Gateway Design for WSN Health Care System
A Smart Gateway Design for WSN Health.pdf (Size: 1.12 MB / Downloads: 77)
Abstract
Using Wireless Sensor Networks (WSNs) in health care system has yielded a
tremendous effort in recent years. However, in most of these researches tasks
like sensor data processing, health states decision making and emergency
messages sending are done by a remote server. Numbers of patient with large
scale of sensor data consume a lot of communication resource, bring a burden
to the remote server and delay the decision time and notification time. In this
paper, we present a prototype of a smart gateway that we have implemented.
This gateway is an interconnection and services management platform
especially for WSN health care systems at home environments, by building a
bridge between WSN and public communication networks, compatible with an
on-board data decision system (DDS) and a lightweight database, which enable
to make the patient’s health states decision in the gateway in order to get faster
response time to the emergencies. We have also designed the communication
protocols between WSN, gateway and remote servers. Additionally Ethernet,
Wi-Fi and GSM/GPRS communication module are integrated into the smart
gateway in order to report and notify information to care-givers. We have
conducted experiments on the proposed smart gateway by performing it
together with a wireless home e-health care sensor network. The results show
that it is reliable and has low latency and low power consumption.
Acknowledgement
First of all, I would like to thank my supervisor Professor Youzhi Xu, who
concerns for me so much during my entire master study and provided me with
many opportunities to participate in international seminars. He is erudite and
lenient. His great ability in grasping the research direction of wireless sensor
network deeply inspired and educated me.
I would like to thank master program coordinator Alf Johansson for being
always helpful and give me a chance to start working on my thesis in this year.
I would like to thank guest researcher Dr. Wei Shen and Dr. Hongwei Huo who
give me so much good ideas in this thesis study and lead me the way to finish
it. I would like to thank Dr. DongYang, who gave me a lot of help in the
research works.
I would like to thank all my teachers and classmates who help me during my
finial thesis study.
1 Introduction
Because of the numerous advantages of Wireless Sensor Networks (WSNs),
include wide coverage, low cost, low power, self-configuration and real-time
data access, WSNs have been used in various areas such as military, health
care, agriculture, environmental monitoring , industry, natural disaster
prevention, wildlife tracking system, intelligent transportation, building
monitoring, space exploration and other fields. It is considered to be one of the
top ten technologies which will change the world in the future.
In this paper, we examine on of these research hot spots, which is using WSNs
in health care system. Using WSNs in health care system which integrates
wireless communications, health care and sensor network, have attracted a lot
of research efforts in recent years.
We are going to discuss how a smart gateway will be used in a health care
system, as well as how to design this smart gateway following the processes of
embedded system development.
1.1 Background
Home health care
Home health care is the largest part of the Swedish elderly care. According to
the statistics on October 1, 2008 around 140000 older persons received old age
care and health care in theirs homes. In many municipalities, home care is the
largest “enterprise”. This type of care is of utmost importance for old people to
be able to live a relatively independent life. Most elderly also prefer to get help
at home instead of at an institution. One of the main reasons why people cannot
stay at theirs home is fear that they may have sudden illness or fall down and
not able to get up. Therefore, they have to move to an old age care institution
that they think would be safer. Many older people, especially in the higher ages
live alone and their children and other relative might not live close to them.
Today, relatively crude alarm systems are available but there is a great need of
more sophisticated system that can monitor, support and alarm when needed.[3]
1.2 Purpose and aims
The goal of this master thesis is to develop and evaluate a gateway for WSN
home healthcare system in order to establish communication between WSN
and Health Care Center (HCC), and meet the requirement of providing caregivers
(home assistant /nurse /HCC /relative) with health state of the elderly.
In a health care system, time required to detect old people’s health state and
time to send message to care givers are very important.
Introduction
2
In the services view, requirements from smart gateway are defined as below:
1. For the elderly, any emergency situation happen to him or her should be
detected and handled immediately.
2. For WSN, sensor nodes are initialized into an efficiency working mode
and less interfere channel. Data from WSN is store and analysis in a
proper way (by gateway or central server).
3. For HCC, it can get the elder’s health state data on time. It should also
have ability to maintenance the health state of sensor nodes in WSN.
4. For care-givers, they can get notice immediate when the elderly is in
danger.
In order to achieve these requirements, these functional requirements are
necessary for smart gateway:
Requirements functions of smart gateway:
Smart gateway is divided into two models: simple model and intelligent model.
In simple model, smart gateway has to:
1. Build up connection between WSN and smart gateway, between smart
gateway and HCC.
2. Transform communication protocol between WSN and PCN (Public
communication Network) in transport layer, also between WSN and HCC
in application layer.
3. Receive data from WSN, and then transmit it to central server in HCC.
4. Implement commands coming from HCC.
In smart model, the smart gateway has to do these tasks:
1. Providing interconnection between WSN and smart gateway, and between
smart gateway and remote server via public communication network
(such as Ethernet, Wi-Fi, and GSM/GPRS).
2. Providing communication protocol transformation between WSN and
various public communication networks.
3. Receiving sensor data from WSN, updating and storing them into onboard
database
4. Providing a DDS to detect the real-time health state (normal,
questionable, dangerous or oncoming dangerous) of the elderly base on
the current received data and the historical data stored in the database.
5. When a dangerous or an oncoming dangerous state of the elderly health is
detected, the gateway sends notifications to the remote server.
Meanwhile, the gateway also sends an emergence SMS to all care-givers.
Introduction
3
6. Providing a wireless access interface for care-givers to check the health
states of the elderly on-site or for the system maintainers to check the
system operating state with laptop or PDA.
7. Implementing response messages for the request requests from remote
servers, such as health data report, sensor network and gateway
configuration commands, etc.
8. Reporting various statistics of the elder’s health state (like average body
temperature, blood pressure) to remote server periodically.
9. Sending short and regular reports in a higher frequency to remote server
with the main purpose to show both the elderly and the system in the
normal state without any problems.
1.3 Delimits
This smart gateway research is part of the WSN healthcare system project from
the research group of Jönköping University. This research is still in the
prototype stage, all data are obtained only through laboratory experiments, did
not use the actual data.
The smart gateway is designed on the assumption that only one elder live in
that house.
Size, price and level of integration of the modules are less considered.
1.4 Outline
The rest of this article is structured as follows.
Followed by Introduction, we will in section 2 focuses on the theoretical
background related to of the smart gateway. Chapter 2 also includes a universal
health care system for wireless sensor networks design presentation, and related
works of embedded gateway design.
Chapter 3 describes the detailed design of the gateway. This chapter contains
the hardware and software design of the gateway, as well as two modes of the
working pattern design.
Chapter 4 describes the process and results of the experiment. We designed
various experiment to test the features of the smart gateway. These features
include wireless sensor networks and wireless network compatibility issues,
system data acquisition and storage experiments, as well as the gateway to send
data packets and emergency messaging latency test.
Introduction
4
In Chapter 5, we have summarized this smart gateway design, and pointed out
the direction for future research work.