performance evaluation of health monitoring network ...

PERFORMANCE EVALUATION OF HEALTH MONITORING NETWORK FOR ELDERLY PATIENT IN HOME MUNEER BANI YASSEIN1*, MOHAMMAD HAMDAN2,3 AND HISHAM A. SHEHADEH1 1

Department of Computer Science, Jordan University of Science and Technology, Irbid, Jordan 2 Department of Computer Science, Yarmouk University, Irbid, Jordan 3 MACS, Heriot-Watt University, Dubai, UAE

AUTHORS’ CONTRIBUTIONS This work was carried out in collaboration between all authors. All authors have read and approved the final manuscript.

Original Research Article

ABSTRACT Health care is very expensive for some countries that suffer from increase in population. In the last decade, health monitoring at home comes to solve this problem especially for elderly people. There are many types of wireless IEEE 802.15.4 sensors that are used for monitoring the health status for patients at home such as ECG sensor, blood pressure sensor, heart sensor and temperature sensor. From previous works in this field, there are some works deal with star topology and other works deal with mesh topology to monitor patients' health status in home environment. In this paper, we present the wireless sensor networks for health monitoring at home using star and mesh topologies. We compare between them by changing the distance between sensor nodes and coordinator node to determine the best network for monitoring patients' health status in home. The constructed system is used to monitor the electrocardiogram health status especially for elderly, Alzheimer's patients and physically disabled people. The results show an improvement for star topology over mesh topology in total packets received and is equal to 64%, 21.4% for energy consumption and 21.2% for average of end to end delay when the distance between sensors nodes and coordinator node equal 6 meters. Keywords: Wireless sensor network; health monitoring; electrocardiogram; IEEE 802.15.4; mesh topology; star topology; Force Sensitive Resistors (FSR) sensors.

1 Introduction In the last decade, health monitoring at home come to solve the problem of increase in population and in the treatment costs in hospitals. Health monitoring at home offers many benefits especially for elderly people and disabled patients to monitor their health status without going to hospitals [1].

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*Corresponding author: Email: [email protected];

Actually there are many types of wireless body sensors which have been created for healthcare systems [2] such as bed sensor, heart rate sensor and infrared heat sensors. These sensors produce vital signals about patients' health state such as blood pressure and heart rate within home area. These vital signals are sent via Ethernet to hospital server and viewed on it to be checked by a nurse or a doctor [3]. Zigbee \IEEE 802.15.4 wireless communication protocol has a set of characteristics and benefits that makes it appropriate to use with biomedical and health monitoring system. This protocol works on 2.4GHz free license band with low complexity, low power consumption and low data rate. Zigbee protocol can support and work on 16 channels with data transmission rate equal to 250 kbps. Zigbee supports access medium with no collision by using Carrier Sense Multiple Access (CSMA) [4, 5, 6]. In this paper we compared between mesh topology and star topology in Wireless Body Area Network (WBAN) by changing the distance between health sensors and coordinator as follows 10 meters, 8 meters and 6 meters. We organized the paper as follows: section 2 presents related work. Section 3 presents health monitoring system in home. Section 4 presents methodology. Section 5 presents simulation parameters. Section 6 presents result. We conclude in Section 7.

2 Related Work In this section we have introduced a comprehensive study on health monitoring network in home health care. Some of the work dealt with star topology. On other hand, other work dealt with mesh topology. Next we summarize few of them. Julong Pan, et al. [1] proposed a new architecture of health care system for elderly patient in home. The system consists of many types of wearable health sensors such as Pulse-Oximeters sensor, electrocardiogram (ECG) sensor and blood pressure sensor. These sensors deployed in patient home by using mesh topology to collect patient health status data after that send two copy of these data to the different devices. The first copy to patient Personal Digital Assistant (PDA) and the second copy to hospital server via Ethernet. Mari Zakrzewski, et al. [3] proposed wireless sensor network for healthcare system at home area. In their study they used Zigbee /IEEE 802.15.4 communication protocol network to send patient health data that taken by a set of health care sensors such as electrocardiography. The system they used in test contains various types of health body sensors at patient’s home such as Electrocardiography (ECG) sensors, HR sensor, bed sensor and infrared heat sensor that collect data about patient health status such as heart rate and send it to server in hospital that save and receive patient data. There are special health applications run on server that viewed patient data to a nurse or a doctor. Juho Merilahti, et al. [7] proposed health monitoring system for the elderly patients at home. They deployed a set of health sensor types using star topology in home area. They used a blood pressure sensor, bed sensor and IR sensor. These sensors used IEEE802.15.4/Zigbee communication technology to send health status data to PC because it can support a wide area network consumes less power and its structure is very simple. The PC retransmitted the data after it has been received to a server in hospital ward. They made 2 tests on this system, the first test one on 71female and its period was 6 weeks and the second test on rehabilitation patient for 2 weeks. The results showed that the system is working well for two tests. Sanjay Sharma, et al. [8] proposed a health monitoring system to monitor ECG, body temperature and respiration rate for patients in hospital. They used wireless communication devices that operated on free license band 2.4 GHz such as nRF24L01 Nordic because it consume less power than wireless standard communication sensors such as Zigbee. They used a star topology to deploy a health sensors in hospital ward in which each three health sensors transferred health data for patients (parameter) to coordinator node. After the patients' health data is aggregated in coordinator node, it retransmit collected data to LCD device to display theses data and send a copy of these aggregated data via Bluetooth to doctors Personal Digital Assistant (PDAs).

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Ka Lun Lam , et al. [9] proposed a novel health monitoring system for patient in home by using two communication protocols IEEE 802.14\Zigbee and WiMAX to send patient health parameters to hospital server. They deployed a set of ECG/IEEE 802.15.4 health sensors in home are by using mesh topology to collect patient Electrocardiography (ECG) vital signals and send it via WiMAX to hospital server to be monitored by a doctor or a nurse. The results after tested the system showed that the system work well with security because ECG/IEEE 802.15.4 sensors encrypt patient data before sends it to hospital server by using ASE algorithm. Sakari Junnila et al. [10] proposed cardiac patients and wheelchair health monitoring remotely in home. They used a set of Zigbee health sensor to measure health status for patients such as weight scale sensor, bed sensor, Heart rate/ECG sensor and blood pressure sensor. These sensors deployed in home area by using star topology to send patient data directly to a laptop. Laptop receives patient data using coordinator node connected with it directly by using USB port after that view patient data on screen by using especial software. Shahram Nourizadeh, et al. [11] proposed a health monitoring system and video call communication with hospital side. The system consists of biomedical sensors fixed in kitchen, WC and bed room in home area. Theses sensors measure the health data for patient after that send it to home gateway (laptop). Laptop is used to save a copy of patient data before send it to hospital server. Hospital server is used to view patient data by using health application. They fixed a camera in home to allow patient make a direct communication with a doctor in hospital side. The system has a set of characteristics (1) a patient can make direct consulting from his/her doctor. (2) Reduced traffic by saving a copy of patient data on a laptop. Reza S. Dilmaghani, et al. [12] proposed a health care in home area. They deployed a set of Electrocardiogram (ECG) sensor regularly in home rooms. These sensors are used to measure a real ECG and heart rate for patient and send it to Internet Connection Board. Internet Connection Board is used to send health parameter that measured by health ECG sensors to hospital server via Internet. Hospital server is used to view patient data by using C# application to allow a doctor or a nurse makes diagnosis on patient health status after that save these data on SQL database for subsequent review. Norman A. Benjamin, et al. [13] proposed a health monitoring in hospital ward for multiple patents. They used Opnet modeller V15.0 to represent their system. They deployed health sensors regularly by using a mesh topology. Each patient in hospital ward has five sensors. Theses sensors are used to measure a health status for all patients and send these data to department building to be reviewed by a doctor. They tested their system by varying the number of patients 5, 10, 20, 25. The results showed that throughput and end-toend delay are decreased when increase the number of patients.

3 Health Monitoring System in Home Health monitoring system is collection of IEEE 802.15.4 health sensors [14, 2] distributed and fixed in rooms. These sensors are used to measure health status for patient such as heart rate, blood pressure rate, electrocardiogram (ECG). These parameters are sent to hospital server by Ethernet for monitoring by doctor or nurse [10]. There are many cases that require monitoring patients continually for a long time. These diseases do not have a cure like Alzheimer and physically disabled status. So, patients can be hospitalized in home under the supervision of a nurse or a doctor. The healthcare providers can be lived with patients at the same home to take care about them. Health monitoring system is depicted in Fig. 1. Zigbee\IEEE 802.15.4 wireless communication protocol has a set of characteristics and benefits that makes it appropriate to use with biomedical and health monitoring system such as low complexity, low power consumption, low data rate and Zigbee supports access medium with no collision by using Carrier Sense Multiple Access (CSMA). This protocol can be operated on different unlicensed frequency bands, data transmission rate, number of channels, and on different frequency ranges. The available radio frequency bands for IEEE 802.15.4 standard along with their characteristics are summarized in Table 1. We have

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chosen the 2.4 GHz band because it's available in Asia and it can support and work on 16 channels with higher data transmission rate equal and up to 250 kbps [4, 5, 6, 15, 16].

Fig. 1. Health monitoring system. Table 1. The available radio frequency bands IEEE 802.15.4 standard Frequency bands 2.4 GHz 868 MHz 915 MHz

Area Asia, Worldwide Europe Australia, America

Frequency range 2405-2480 868.3 902-928

Data rate 250 20 40

Channel number(s) 16 channels 1 channels 10 channels

There are many of types of health sensors that are used to monitor health status for patients in home area [2]: (1) Pulse Rate Sensor: is used to measure a heart rate for a person. (2) ECG Sensor: is used to measure electrocardiography especially for heart rhythms patients. (3) Temperature Sensor: is used to measure and sense temperature of the person body. (4) Force Sensitive Resistors (FSR) sensors: if the patient sits or lays part of body on these sensors, then the sensors generate the health parameter. Fig. 2 and Fig. 3 present an example of bed, chair, toilet, pillow sensors [17, 20].

Fig. 2. Bed, chair and toilet sensors.

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Fig. 3. Pillow sensors.

4 Methodology From literature review, we can percept that some of works monitor patients' health status by using star topology and other works used mesh topology [1, 3, 7, 8, 9, 10, 11, 12, 13]. In this paper, we judge between these topologies to determine the best network for monitoring patients' health status in home environment. Real time applications such as health monitoring systems are affected by changing the topology and the distance between sensors nodes and coordinator node. In this paper we will design two different types of network topologies (mesh and star), compare between them by changing the distance between health sensors and coordinator as follows 10 meters, 8 meters and 6 meters to show which is the best. Until we can estimate the performance of Wireless Body Area Network (WBAN) in home we need designing a Zigbee network by using standard health parameter with deferent network topologies (Mesh and Star). Finally, we will compare between them in terms of: 1. 2. 3. 4. 5.

Total Packets Received. Energy consumed: it contains four modes (Transmit mode, idle mode, Receive mode and Sleep mode). Average Jitter. Number of data packet sent. Number of data packet received

5 Simulation Parameters We assumed patient home area equal 20m×20m. We distributed 6 health sensors nodes in 6 rooms as follows: bed room, living room, dining room, kitchen, bathroom and office room. Also, we have assumed that the patient has a bed sensor, ECG Force Sensitive Resistors (FSR) sensors to measure the electrocardiogram continually. These sensors are fixed in patient home rooms to send patient data to the sink. The sink node is connected directly with a small PC. The proposed patient home and health network are depicted in Fig. 4. We used a standard health Parameters in the simulations. These simulation parameters are listed in Table 2. We have used the 6, 8, 10 meters to build the network, because the average of rooms' dimensions in Asians homes do not exceed (10×10) meters. Also, the averages of dimensions for these rooms do not reduce than

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(6 × 4) meters. To make real time detection of Electrocardiogram (ECG) for patient the transmission rate must equal 10 packets/sec with packet size equal 50 [3,17, 18, 19].

Fig. 4. Proposed patient home and health network. Table 2. List of simulation parameters Parameter Simulator Patient Home Simulation time Radio type Frequency Band The distance between health sensors and coordinator Antenna height Energy model Topology types Item to send Item size Transmission rate Start time End time

Values QualNet v5.2 20× 20 1000 sec 802.15.4 2.4 GHz 10 meters, 8 meters, 6 meters 0.08 MicaZ Star, Mesh 0 50 bytes 10 packets/sec 15 sec 1000 sec

6 Results In this section we compare between mesh topology and star topology in Wireless Body Area Network (WBAN) by changing the distance between health sensors and coordinator as follows 10 meters, 8 meters and 6 meters. We have used an efficient network simulator program to implement our work (QualNet v5.2). Also, we have made over 10 runs for each topology to extract the results.

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Fig. 5. provides a comparison between mesh and star topology in terms of Total Packets Received at different distances 10 meters, 8 meters and 6 meters. The results show that the total packets received are increased slightly in both star and mesh topologies when the distances are decreased between sensors nodes and the sink. We can notice that star topology outperforms the mesh topology in term of Total Packets Received at different distances 10 meters, 8 meters and 6 meters.

Total Packets Received 50000 40000 30000 star Topology

20000

Mesh topology

10000 0 10

8 Distances (in meters)

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Fig. 5. The Total Packets Received between mesh and star topology at different distances10 meters, 8 meters and 6 meters Fig. 6. provides a comparison between star and mesh topology in terms of Average End-to-End Delay (s) at different distances 10 meters, 8 meters and 6 meters. The results show that Average End-to-End Delay (s) are decreased slightly in both star and mesh topologies when the distances are 10 meters and 8 meters between sensors nodes and the sink. While in the distance of 6 meters the Average End-to-End Delay (s) in mesh topology is return to increased sharply. We can notice that mesh topology outperforms the star topology in term of Average of end to end delay at distances 10 meters and 8 meters.

Average End-to-End Delay (sec) 1 0.8 0.6 Star Topology

0.4

Mesh Topology

0.2 0 10

8

6

Distances (in meters)

Fig. 6. Average of end to end delay between mesh and star topology at different distances 10 meters, 8 meters and 6 meters.

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Fig. 7. shows a comparison between mesh and star topology in terms of Energy consumed by taking the summation for the four energy consumption modes (Receive mode, Transmit mode, Sleep mode and idle mode) at different distances 10 meters, 8 meters and 6 meters. The chart shows that the Energy consumed in four models are decreased slightly in star topology, while it increased slightly in mesh topology when the distances are 10 meters and 8 meters and 6 meters between sensors nodes and the sink. Star topology outperforms the mesh topology in terms of The Energy consumed at different distances 10 meters, 8 meters and 6 meters.

Energy Consumed in mWh 3 2 Star Topology

1

Mesh Topology 0 10


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Fig. 7. The Energy consumed between mesh and star topology at different distances10 meters, 8 meters and 6 meters. Fig. 8. provides a comparison between mesh and star topology in terms of Average Jitter (s) at different distances 10 meters, 8 meters and 6 meters. The chart shows that the Average Jitter (s) are decreased slightly in star topology, while it approximately maintain stable in mesh topology when the distances are 10 meters and 8 meters and 6 meters between sensors nodes and the sink. Mesh topology outperforms the star topology in terms of Average Jitter (s) at distances 10 meters, 8 meters and 6 meters.

Average Jitter (sec) 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0

Star Topology Mesh Topology

10


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Fig. 8. The Average Jitter (s) between mesh and star topology at different distances 10 meters, 8 meters and 6 meters. Fig. 9. provides a comparison between mesh and star topology in terms of Number of data packets sent at different distances 10 meters, 8 meters and 6 meters. The results show that the Number of data packets sent

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are increased dramatically in mesh topology, while it approximately maintain stable in star topology when the distances are 10 meters and 8 meters and 6 meters between sensors nodes and the sink. Mesh topology outperforms the star topology in term of The Number of data packets sent in MAC-802.15.4 at different distances 10 meters, 8 meters and 6 meters.

Number of Data Packets Sent 9400 9200 9000 Star Topology

8800

Mesh Topology

8600 8400 10


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Fig. 9. The number of data packets sent in MAC-802.15.4 between mesh and star topology at different distances 10 meters, 8 meters and 6 meters. Fig. 10. provides a comparison between mesh and star topology in terms of Number of data packets received at different distances 10 meters, 8 meters and 6 meters. The results show that the Number of data packets received are increased slightly in both star and mesh topologies when the distances are decreased between sensors nodes and the sink. Mesh topology outperforms the star topology in term of The Number of data packets received in MAC-802.15.4 at different distances 10 meters, 8 meters and 6 meters.

Number of Data Packets Received 10000 8000 6000 Star Topology

4000

Mesh Topology

2000 0 10


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Fig. 10. The number of data packets received in MAC-802.15.4 between mesh and star topology at different distances 10 meters, 8 meters and 6 meters.

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7 Conclusions and Future Work In this paper we used QualNet V5.2 simulator to design wireless sensor network at home. We compared between mesh topology and star topology by using standard health parameter and changing the distance between health sensors and coordinator as follows 10 meters, 8 meters and 6 meters. The experimental results showed Star topology is the best at the different distances because it has the lowest energy consumption and highest average value for total packets received and throughput. The percentage of improvement for star topology over mesh topology in total packets received equal 64%, 21.4% for energy consumed and 21.2% for average of end to end delay when the distance between sensors nodes and coordinator node equal 6 meters. In future we will focus on the following aspects: 1) Estimate the performance of the health network by varying number of health sensor in each room in patient home. 2) Using deferent types of communication protocol network in study and compare between them like WiFi/IEEE802.11, WiMAX and Zigbee/IEEE802.15.4. 3) Make hybrid network consists of mesh, star and tree cluster topologies and compare it with star topology and mesh topology.

Competing Interests Authors have declared that no competing interests exist.

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