JOURNAL OF ELECTRONIC SCIENCE AND TECHNOLOGY, VOL. 11, NO. 3, SEPTEMBER 2013 241

Performance Evaluation of IPv4/IPv6 Networks for Ubiquitous Home-Care Service

Cheng-Chan Hung and Shiow-Yuan Huang

Abstract⎯ Because of rapid development in network the Bluetooth (IEEE 802.15.1), Zigbee (IEEE 802.15.4), technology, Internet usage has become widespread. It wireless fidelity (Wi-Fi), 3G or 3.5G (high speed downlink allows users with sensing devices to obtain medical data packet access, HSDPA) generation universal mobile for healthcare, such as physiological signals, voice, and telecommunications system (3G[2] or 3.5G[3] UMTS), and video streams from telemedicine systems, and to send WiMax[4],[5] networking technologies. However, all of these the healthcare data to back-end database systems, wireless technologies are connected to the Internet via a creating a ubiquitous healthcare environment. However, mobile sensor gateway that connects the this environment requires a widespread and suitable to the backbone network by establishing an IPv6 tunnel and network. IPv6 ( version 6) is the translating IPv4 to IPv6. General gateways, such as the next-generation Internet protocol that will be the ADSL (asymmetric digital subscriber line) modem, cable protocol of future networks; it improves many modem, and FTTH (fiber to the home) or FTTB (fiber to shortcomings of IPv4. In this paper, we propose an the building) by VDSL (very high data rate digital IPv6/IPv4 U-home-care test system and analyze the subscriber line), connect LANs (local area network) to ISPs network’s parameters though a series of tests by (Internet service provider), serving as transmission media adjusting network parameters to find the optimal design gateways associated with different transmission media. The for applications in the IPv6/IPv4 U-home-care service so introduction of high-speed data rates, wide bandwidth, and as to assure good performance and high quality. digital and encrypted communication technologies enable

Index Terms⎯Healthcare, Internet protocol version the delivery of audio, video, and medical data everywhere. 6, performance, telemedicine, ubiquity. All of above improve on some of the limitations existing m-health technologies[6] and provide a better platform for U-care services. 1. Introduction Most current home networks are asymmetrical networks[7] where the uplink bandwidth is smaller than the As a consequence of development in science and downlink bandwidth. This asymmetry is because more data technology, the medical sensing technology is evolving is downloaded than uploaded in general Internet use. This, from the previous electronic care (e-care) and mobile health however, may cause some problems for telemedicine data (m-health) to ubiquitous care (U-care). What is meant by transmission because sensing data must be uploaded. ubiquity? It means that it covers mobility of sensor Furthermore, the common Internet protocol of networks is networks, security, standards, integration (health system, service model), CAD (computer-assisted decision), and IPv4 (Internet Protocol version 4). IPv6 (Internet Protocol U-home-care (U-healthcare at home). Ubiquitous version 6) is the next generation Internet protocol and has computing[1], also called pervasive computing, describes many new features, such as large address space, Internet environments where a user is surrounded by numerous operations support, an extension of the encrypted special-purpose applications running on networked authentication mechanism, enhanced addressing information appliances. It is characterized by physically capabilities, an automatic addressing mechanism, embedded sensor systems, a ubiquitous network, and simplification of the header format, etc. Therefore, using application-specific devices. IPv6 is an asset for U-care networks, and the requirements of U-care networks are listed in Table 1. But, recently, in Recently, there has been an increase in research focused [8] on the production of commercial U-care systems based on the mostly performance evaluation of telemedicine , IPv4 networks are usually used. In our research, we analyze the performance of IPv6 Manuscript received February 17, 2013; revised April 2, 2013. C.-C. Hung is with the Department of Computer Science & Information and IPv4, which transmit UDP () Engineering, Asia University, Taichung 41354 (e-mail: cctks.hung@ and TCP (transmission control protocol) packets in msa.hinet.net). U-home-care systems. The TCP is a connection-oriented S.-Y. Huang is with the Department of Photonics and Communication protocol in which the TCP packets are transmitted before it Engineering, Asia University, Taichung 41354 (Corresponding author e-mail: [email protected]). establishes a connection. It is a reliable delivery mechanism Digital Object Identifier: 10.3969/j.issn.1674-862X.2013.03.001 for data transmission. On the other hand, UDP is a 242 JOURNAL OF ELECTRONIC SCIENCE AND TECHNOLOGY, VOL. 11, NO. 3, SEPTEMBER 2013 connection-less protocol and is unreliable, but it has the 2.1 Transmission Parameters and Category of advantage of high transmission efficiency. Thus, UDP is Networks in U-Healthcare Networks often used to transmit real-time voice and video data on The U-home-care service has three parts: physiology networks, but it needs to meet a higher QoS (quality of data (vital signals), voice, and video streams[9]. In this paper, service) requirement for telemedicine data transmission. we discuss the buffer size needed to support medical For these reasons, we decide to evaluate the network services to assure that no packets are dropped during protocols that are most suitable for U-home-care in the transmission. A buffer size of 12 packets for audio service, future. four packets for medical data, and 25 packets for video This paper is organized as follows: Section 2 focuses on service are required. But in the case of [9], an IPv4 medical the U-healthcare requirements of the project and the service network was used. Therefore, in this paper, we will description of the QoS requirements in U-healthcare evaluate the requirements for medical data, voice, and networks. Section 3 describes the scenarios of U-home-care video streams, and measure the value of delay, jitter, and in two types of networks. Section 4 illustrates the packet loss, and try to find the differences between measurement models that we use to test the application U-healthcare networks using IPv6 and IPv4. Most current networks in Taiwan access the Internet via platforms of the U-home-care environment. Section 5 [7] focuses on the performance requirements of medical video ADSL (79.2%) , Fiber (8.8%), and Cable Modem (7.2%) networks are also used[7]. The characteristics of ADSL data, voice data, and data used in U-home-care. Section 6 networks are that the uplink and downlink bandwidths are concludes with a summary and areas for future research. asymmetrical, and the uplink bandwidth is relatively small.

However, most U-healthcare data are uplink and 2. U-Healthcare Requirements transmitted from a client to a back-end server. Therefore, to structure a U-healthcare environment for the future, we Along with social and economic developments, medical must consider the issue of ADSL in IPv4 and IPv6 advances have enabled people to increase their life U-healthcare networks. expectancy with the consequent gradual aging of the population. The problem of an aging population needs 2.2 Data Rate and QoS Requirements of U-Healthcare urgent attention in the 21st century. Most healthcare applications can be divided into three The increasing demands of healthcare for the elderly are kinds: 1) medical data transmission, mainly ECG the most pressing current need and will continue to grow in (electrocardiogram), EEG (electroencephalography), and the future. Therefore, as we consider the increasing blood pressure, etc.; 2) audio from a stethoscope or VoIP demands for healthcare for the elderly that may include communication applications; and 3) motion video and mobile care (m-care), it is necessary to establish a new type endoscopic video transmission. Each has different data rate of healthcare system that uses the network technology to transmission requirements and QoS () requirements. provide U-care services. When a person urgently needs Problems with network QoS can be recognized by the healthcare, the U-healthcare system can issue an immediate packet loss, jitter, and delay. These can be further divided warning through the network so to enable healthcare into two categories: their affect on medical multimedia and workers to locate the person quickly and efficiently and medical data. Regarding medical multimedia, the human provide the necessary emergency treatment. ear cannot detect delay below 150 ms of end-to-end delay, Table 1 shows the requirements of a U-healthcare so voice jitter or delay cannot be more than 150 ms for the network and the solutions IPv6 provides. digital audio stethoscope. We refer to [10], where the acceptable delay was about 400 ms. But [11] mentioned that Table 1: Requirements of U-care and characteristics in IPv4/v6 networks a reasonable delay goal was 250 ms, and for private networks it was 200 ms. For this reason, we chose a delay Requirements of Feature of IPv6 Feature of IPv4 goal for our network of less than 250 ms as a standard U-care network requirement. Large number of Large IP space Will be exhausting Medical data also can be divided into two types: medical sensors real-time and non-real-time. The real-time data is used for Sensor’s IP Stateless auto-configuration Provided by a monitoring daily life of patients with chronic conditions automatically (unnecessary server) dedicated DHCP server and providing emergency notification when the system Real-time More QoS support (ex. Limited QoS-functions transmission traffic class, flow label) relays abnormal physiological data. Non-real-time medical Sensors hand off data is mainly used for the data transmission of routine Mobile IPv6 (improved) Mobile IP and roaming information, such as demographic data, laboratory and Security issue of Additional and no real clinical data, medical history, electromyograms, magnetic Integrated security (IPSec private medical standard encryption resonance images, and digital radiography. Medical encryption, AH, ESP) data on internet methods exist multimedia streams are often used in medical diagnosis (e.g. IPv6 and IPv4 Dual stack, tunneling, Dual stack, tunneling, colonoscopy) so that biomedical data must be transmitted translation translator translator along with telemedicine streams. Therefore, we focus on HUNG et al.: Performance Evaluation of IPv4/IPv6 Networks for Ubiquitous Home-Care Service 243 the QoS requirements for our network for telemedicine networking technologies, it is possible to develop a streams and provide a variety of requirements for QoS in ubiquitous healthcare system using a suitable network the healthcare appliances referenced in Section 5. We refer platform. Furthermore, the number of 3G mobile users is to the parameters of the data rates used in our system and in over 55.8% of all mobile users in Taiwan[13]. Therefore, to [3] and consolidate them in Table 2. test our U-home-care system, we chose the three currently 2.3 Advantage of QoS in IPv6 Networks pervasive wireless networking technologies in Taiwan, namely Bluetooth, Wi-Fi, and 3.5G (HSDPA). In a U-healthcare environment, different data traffics First, in our U-home-care scenarios, the front-sensor with different classes of QoS requirements have to be uses the personal area network (PAN) of the Bluetooth transmitted simultaneously. The header in an IPv6 packet is device to obtain the healthcare data (e.g. biomedical data, different from that in an IPv4 packet. The IPv6 header has voice, and video stream). Then, the healthcare data are two fields, namely the traffic class and flow label. The moved through an intermediate network gateway device priority level of the traffic class is divided into two main (e.g. Notebook, PDA, or mobile phone with Wi-Fi and categories, congestion-controlled and the non-congestion- 3.5G) to transfer information to the Internet. controlled. Congestion control and non-congestion-control In the current design, the mobile U-homecare device priorities are divided into eight grades. Therefore, in an will choose a suitable gateway (Wi-Fi or 3.5G) in IPv6 network, the information can be divided into two accordance with the available network. The choice will be types for QoS; one packet is emergency information and [12] handled by the USIM (universal subscriber identity module) the other is sensor measurement information . This card, which gives a high priority to Wi-Fi or 3.5G designation will protect the transmission of emergency depending on which one has a stronger signal. When the information packets during IPv6 . This transmission network is selected, the healthcare data will be is an additional advantage of IPv6 over IPv4. transferred to the back-end system and recorded for use by various healthcare applications. 3. U-Home-Care Scenarios 3.1 Proposed U-Home-Care Scenario The advent of a large number of wireless networking To create a ubiquitous healthcare environment, the technologies allows a mobile host to be equipped with system must consider the attributes of the different multiple wireless interfaces (e.g. Bluetooth, Wi-Fi, and environments. To do this, we will divide the front-sensors 3.5G, etc.), each providing access to different wireless into two types: (1) the indoor area of care center or home, networks. Because of the emergence of these wireless (2) outdoors in an emergency condition.

Table 2: Detailed table of the medical service’s requirements with QoS and data rate QoS requirements Appliances Real time Data rate Delay Jitter Packet loss service Medical

VoIP with hospital experts Yes < 250 ms < 250 ms <10% 40 Kbps–64 Kbps Telemedicine video Yes < 250 ms < 250 ms <15% 160 Kbps–384 Kbps Medical video for

teleconsulation Medical Yes < 250 ms < 250 ms <15% 1.544 Mbps

multimedia (ophthalmoscope, proctoscope, etc.) Patient’s RFID authentication No < 1 s–2 s — 0% 1 KB (text size) Laboratory and clinical data, No < 1 s–2 s — 0% 1 KB (text size) medical history <1 s (Sampling Digital sphygmomanometer Yes — 0% < 4 Kbps frequency 2 h) <1 s (Sampling Digital thermometer Yes — 0% < 4 Kbps frequency 1 s) <1 s (Sampling Respiration Yes — 0% < 4 Kbps frequency 1 s)

<1 s (Sampling Heart rate Yes — 0% < 4 Kbps

Medical data Medical frequency 1 s) Electroencephalogram (EEG) Yes <1 s — 0% < 10 Kbps Electrocardiogram (ECG) Yes <1 s — 0% < 15 Kbps Ultrasound, cardiology, No < 1 s–2 s — 0% 256 KB (image size) radiology Magnetic resonance image No < 1 s–2 s — 0% 384 KB (image size) Digital radiography No < 1 s–2 s — 0% 6 MB (image size)

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We assume that patients with chronic conditions are (Wi-Fi or 3.5G) is used, (5) it is via physical media (802.11, normally at a care center or at home. In normal HSDPA, Ethernet, Fiber), and (6) it is transmitted to the circumstances, the biomedical data is captured by a back-end server’s receiving program. Bluetooth-enabled device and transmitted via Wi-Fi to the According to the foregoing description, we have drawn healthcare center. Monitoring items include routine the U-home-care system as a layered architecture, as shown biomedical data such as ECG, EEG, blood pressure, and in Fig. 2. blood glucose. Long-term monitoring and recording is helpful for tracking and treating patients with chronic 4. Measurement Model conditions. Regarding an outdoor emergency notification and 4.1 Measurement of the Network Platform rescue, when patients are outdoors and an emergency arises, From Fig. 1, we constructed the U-home-care network the U-home-system will use the same Bluetooth sensors to on four different networks: 3.5G HSDPA, ADSL, optical capture their biomedical data. However, the gateway fiber, and Ethernet (802.3ab). Table 3 shows the difference service is replaced by a 3.5G mobile phone that can provide in bandwidth for the ISPs (Internet services providers) of real-time communication to a first-aid unit via a 3.5G base the four network standards. station. If the first-aid unit cannot reach the individual 4.2 Measurement Model quickly, hospital experts can provide the necessary first-aid guidance through an informant, and via connection with the To understand the transmission performance under informant, and they can diagnose the vital signals. All various parameters of IPv4/v6, we designed a measurement mentioned above are important factors need to increase the model as shown in Fig. 3 for the U-home-care network success rate of rescue operations. The foregoing scenarios transmission of biomedical data (TCP), voice, and video of the U-home-care are shown in Fig. 1. (UDP) streams, respectively. We adjusted the four kinds of The transmission system at the frontend of the entire transmission parameters, the buffer size, packet size, UDP system is constructed with a wireless overlay network data rate, and TCP data rate in order to measure packet loss, (WON) as shown in Fig. 1. All of the U-home-care delay, and jitter, and to identify the parameters that provide networks are connected through the Internet to the relevant both performance and QoS in the U-home-care service. care service center, which provides electronic health records (EHRs), U-healthcare web monitoring services, and a hospital backend, regardless of whether information comes from an indoor Wi-Fi system or an outdoor 3.5G system. 3.2 Layered Architecture of U-Home-Care System The U-home-care network gateway is over IP networks so we must take into account the transmission performance issues of IPv4 and IPv6 networks. The transmission layers of the system are in the following: (1) delivery starts with Fig. 2. Layered architecture of U-home-care system. Bluetooth sensors that capture healthcare data (e.g. biomedical data, voice, and video), (2) healthcare data are Table 3: Bandwidth of network services in measurement platform transmitted via TCP or UDP transmission protocols, (3) of U-home-care Network Bandwidth IPv6/IPv4 network protocols are used, (4) the base station ISP standards Downlink Uplink 3.5G (HSDPA) Chunghwa Telecom 3.6 Mbps 384 Kbps ADSL Chunghwa Telecom 2 Mbps 256 Kbps Fiber TWAREN 1 Gbps 1 Gbps Ethernet(802.3ab) ASIA University 1 Gbps 1 Gbps

Fig. 1. U-home-care system scenarios. Fig. 3. Measurement model. HUNG et al.: Performance Evaluation of IPv4/IPv6 Networks for Ubiquitous Home-Care Service 245 In this measurement scenario, as shown in Fig. 4, point Table 4: Actual bandwidth & delay in our U-home-care networks A is an immobile U-home-care back-end system to which Actual Point A (back-end server) Point B (Gateway) all of the healthcare data will be transmitted. Point B is a bandwidth & mobile node with Wi-Fi and 3.5G. The purpose is to delay Fiber (Campus network) ADSL 3.5G* measure the performance of our U-home-care system and Downlink 24.44 Mbps 1.74 Mbps 1.02 Mbps improve the quality of services offered by dimensioning the Uplink 24.44 Mbps 242 Kbps 232 Kbps buffer size, packet size, UDP data rates, and TCP data rates. IPv4 delay 46 ms 46 ms 100 ms –300 ms

Several tests were conducted using the system over IPv4/v6 IPv6 delay 4 ms 46 ms 100 ms –300 ms 3.5G UMTS and ADSL in urban areas (Taichung). *A condition of full signal in Taichung. However, after the 3.5G test we found that 3.5G signals are only prevalent in the city area. In our test area (Taichung), Prior to this evaluation, we measured the traffic using 3.5G does not have a widespread penetration. For this samples of medical streams (voice and video) in the reason, in subsequent tests, we used only the ADSL U-home-care environment. We compared this with a network to do the measurements because ADSL has a telemedicine system developed by [14] that uses MPEG-2 bandwidth similar to 3.5G. for its video CODEC (coder-decoder) standard. The The measurement scenario we designed is shown in Fig. CODEC standard of our U-home-care system is more 4. First, we tested the biomedical data transmission without efficient. At present, many HD (high definition) video, UDP streams and transmitted simultaneously 256 Kbps telecommunication, and telemedicine devices are using the video streams and 64 Kbps voice streams. We obtained the H.264 CODEC video standard. It has a higher compression jitter and packet loss measurements of the ADSL network, ratio and a higher quality CODEC than the MPEG-2 which were caused by the UDP streams. CODEC; it is recommended by ITU-T as a video standard. Second, to measure the influence of UDP in biomedical Therefore, we used H.264 in our U-home-care system as data (TCP) transmission, we selected four types of vital the video CODEC standard. In addition, we used G.711, physiological data, digital sphygmomanometer, digital also known as pulse code modulation (PCM). It is a thermometer, respiration, and heart rate, which were sorted commonly used waveform CODEC with a sampling rate of and shown in Table 2. These represent the medical data that are most commonly used in indoor monitoring. It is totally 8 k samples per second, resulting in a 64 Kbps bit rate. This about 16 Kbps. In addition, we also select non-real time standard is required by many technologies (e.g. H.320 and appliances (bandwidth limits with 64 Kbps/120 Kbps) to H.323 specifications). The medical stream traffic of facilitate understanding the influence of biomedical data CODEC is shown in Table 5. (TCP) transmission. The measurement results are described 5.1 UDP Jitter Results in Section 5.2. First, at point B, we injected a fixed bit rate of UDP Fig. 4 shows the network layout. We take streams at 320 Kbps (VoIP at 64 Kbps and video at 256 measurements for QoS at point A, and we measure traffic flow at point B. Kbps). Next, we changed the buffer size in a geometric progression from 1 Kb to 8192 Kb in order to measure the 5. Measurement Results influence of these changes. From the measured results in Fig. 5, there is no obvious variation in jitter for the different To impartially measure the impartial values on Internet, buffer sizes; the measured values are within the error range we chose four different test times (off-peak, peak, off-peak, of ±1 ms, and the packet loss rate is 0%. However, we can and peak) in a day and take the average test values to record. clearly see that the jitter is less at about 4 ms in IPv4 versus The actual values of measured environment results are IPv6, because the IPv6 network needs tunneling technology shown in Table 4. to be compatible in IPv4 network. In Taiwan, the 3.5G bandwidth is shared, which is To test the limitations of ADSL transmission by UDP allocated according to the number of users. As a result, the streams, we simultaneously transmitted two streams at actual bandwidth is not fixed and the network delay is 256 Kbps from point B. The results are shown in Fig. 6. unstable. For this reason, in the following measurement, we (The buffer size is same as in the previous test.) The results used the ADSL network platform that is in common use by show that by increasing the buffer size it can reduce the the population and care centers. jitter from 50 ms to 40 ms, but it cannot reduce the packet loss rate (average packet loss rate was 56.14%). Furthermore, we find the effect of buffer size using IPv4 is smaller than that using IPv6. When the buffer size is set to Table 5: Medical stream traffic of CODEC in the evaluation test

Medical UDP Bit rate CODEC Resolution stream traffics Busy Idle Voice G.711 8 kHz 64 Kbps 40 Kbps Fig. 4. Measurement scenario of IPv6/IPv4 U-home-care test Video H.264 352×288@15 256 Kbps 160 Kbps system. 246 JOURNAL OF ELECTRONIC SCIENCE AND TECHNOLOGY, VOL. 11, NO. 3, SEPTEMBER 2013 1024 Kb, the jitter in IPv4 can only be reduced about 5 ms. 80 70 Using IPv6, the jitter can be reduced about 10 ms. As a 60 result, we see that when the buffer size is greater than, or 50 40 IPv6 equals to 1024 Kb, it can improve the jitter caused by 30 network bandwidth constraints in the IPv6 network; and if 20 IPv4 10

Packet loss rate (%) the buffer size is higher than 1 Mb, the jitter will not affect 0

performance. 64

128 256 512 To understand the effect of packet size, we changed the 1024 2048 4096 Packet size (bits) packet size in the setup; the parameters of packet size were Fig. 8. UDP packet size affects packet loss rate in IPv4/v6 increased from 64 bits to 4096 bits, by geometric (ADSL). progression. We discovered that the relative effects of jitter and packet loss were dependent on the packet size in 5.2 Effects of the Interaction of UDP Streams and TCP IPv4/v6, which are obvious as shown in Fig. 7 and Fig. 8, Biomedical Data respectively. We also find that the best packet size is 1024 The measurements of section 5.1 are all of UDP stream transmission tests. However, in the U-home-care service, it bits, because a higher packet size results in a substantial is necessary to regularly transmit the biomedical data of increase in jitter. When the packet size is less than 1024 bits, patients with chronic conditions to the back-end server. The it increases the packet loss rate. purpose of this section is to understand the effects of UDP Finally, we also attempted to transmit two 256 Kbps streams for biomedical data transmission. As listed in Table streams by changing the packet size at point B and 2, U-home-care applications require a delay of less than obtaining the packet loss rate at point A. The results were a 250 ms. Therefore, we chose 250 ms as the limit of delay. packet loss rate of over than 50%. We do not provide the Jitter is technically the measurement of the variability over results. time of the across a network. It should be less than 100 ms. If the value of jitter is smaller than 100 ms, it can 19 be corrected. However, to maintain a jitter of less than 100 18 17 ms, medical data stream transmission must be reduced in 16 this network. 15 14 IPv6 A. Effects of Jitter Jitter (ms) 13 12 IPv4 We tested three speeds of TCP data rates: 120 Kbps, 11 64 Kbps, and 16 Kbps in an IPv4/v6 network. In total, there 10 1 2 4 8 16 32 64 128 235 512 are six test samples. The buffer size is set at 1024 KB as the Buffer size (Kb) test standard (refer to Section 5.1). We changed the UDP Fig. 5. UDP transmission jitter with different buffer sizes in data rate and observed the effect on UDP stream biomedical IPv4/v6 (ADSL). data transmission. We observed, as shown in Fig. 9, that the TCP 16 Kbps transmission in IPv4/v6 has low jitter and the 60 difference in jitter is small in both. This is consistent with 56 the expected results. 52 In addition, the results for jitter at TCP 64 Kbps and 48 TCP 120 Kbps transmission in IPv4/v6 show that jitter in 44 IPv6 IPv6 are lower than that in IPv4. For this reason, we find Jitter (ms) 40 IPv4 that high TCP data rate transmission has advantages in IPv6 36 32 over IPv4. Furthermore, when the UDP data rate is over

1 2 4 8 16 32 64 256 Kbps, the jitter will be somewhat lower than at the 128 256 512 1025 2048 4096 8192 other, smaller UDP data rate. We will discuss the reason for Buffer size (Kb) this result in Section C. Fig. 6. Two parallel streams transmission jitter with different 35 buffer sizes in IPv4/v6 (ADSL). 30 40 25 35 IPv6 TCP 120 Kbps 20 IPv6 TCP 64 Kbps 30 15 IPv6 TCP 16 Kbps 25 Jitter (ms) IPv4 TCP120 Kbps 20 10 IPv4 TCP 64 Kbps 15 IPv6

Jitter (ms) 5 IPv4 TCP 16 Kbps 10 IPv4 5 0

0 16 32 64

128 192 256 320 384 448 512 64

128 256 512 UDP data rate (Kbps)

1024 2048 4096 Packet size (bits) Fig. 9. Effect of jitter in both UDP streams and TCP medical data Fig. 7. UDP packet size affects jitter in IPv4/v6 (ADSL). transmits (ADSL). HUNG et al.: Performance Evaluation of IPv4/IPv6 Networks for Ubiquitous Home-Care Service 247

B. Effects of Delay 100 Next, we measured the effects of TCP delay in 90 80 biomedical data transmission caused by UDP streams. 70 From Fig. 10, we can see that the maximum value for the 60 IPv6 TCP 120 Kbps IPv6 TCP 64 Kbps 50 stable transmission at TCP 16 Kbps (i.e., TCP delay<250 40 IPv6 TCP 16 Kbps ms) is around the UDP stream of 192 Kbps; however, the 30 IPv4 TCP120 Kbps IPv4 TCP 64 Kbps 20 maximum value of the stable transmission at TCP 64 Kbps Packet loss rate (%) IPv4 TCP 16 Kbps 10 is around the UDP stream of 128 Kbps; and in TCP 0

120 Kbps, it is around the UDP stream of 64 Kbps. In this 16 32 64 128 192 256 320 384 448 512 case, the TCP delay, measured by UDP streams at a higher UDP data rate (Kbps) data rate (over 192 Kbps), will significantly increase the rate of delay. In summary, the delay in IPv6 is less than that Fig. 11. Packet loss rate in both UDP streams and TCP medical data transmission (ADSL). in IPv4. Furthermore, it is more apparent in the TCP data rates, especially at 120 Kbps. In summary, from the previous tests, we see that in IPv6 C. Effects of Packet Loss Rate networks, the jitter, delay, and packet loss rates are a little Finally, we discuss packet loss rates. From Fig. 11, we better than those in IPv4 networks. Our tests also illustrate observe the following: (1) in both IPv4 and IPv6 at TCP 16 that there is no difference in IPv4/v6 network performance Kbps, when the UDP stream of data rate is 256 Kbps, the when the transmission of UDP data rates is less than packet loss is 0%; (2) in IPv4 at TCP 64 Kbps and at UDP 64 Kbps. At present, our U-home-care applications use a

192 Kbps, there is a 1% to 3% packet loss, but in IPv6, a TCP data rate at about 16 Kbps for real-time transmission,

41% packet loss is introduced at UDP 320 Kbps; and (3) in and the UDP data rate for telemedicine is about 256 Kbps. IPv4 at TCP 120 Kbps and UDP 64 Kbps, a packet loss rate In the future, with a wider application of U-healthcare, of 2.5% or 64% is produced, but in IPv6, a UDP data rate there will be a need for higher transmission rates for data higher than 256 Kbps results in a packet loss of 17% or and a higher mobility. Based on the needs of our system, 65%. From these tests, we find that, under the same and the results of our tests, IPv6 networks will be a better conditions, the packet loss rate in IPv6 is lower than that in choice for U-healthcare in the future. IPv4. Regarding the discussions in Section A, we find that 6. Conclusions with a UDP data rate of over 256 Kbps, the jitter is lower than that at other relatively smaller UDP data rates. By Most home networks in Taiwan have an uplink comparison with Fig. 9 to Fig. 11, we find that when the bandwidth of 242 Kbps of ADSL or 232 Kbps of 3.5G, UDP data rate is at 256 Kbps, because of the limitations of separately. Due to the U-healthcare requirements given in ADSL uplink bandwidth, there is transmission congestion Section 2, and the measurement results of Section 5, we see at point B which produces a packet loss. Because the UDP the effects of different data rates for TCP and UDP data packet is dropped by the network (i.e., packet loss), the transmission in U-homecare networks. If the buffer size is TCP delay is significantly increased. By contrast, the jitter set to 1024 Kb, and the packet size is set to 1024 bits, then in UDP packets is reduced at point A. However, it may be the transmission of medical data at 256 Kbps UDP stream possible to use packet loss as a compromise to attain a and 16 Kbps TCP is possible. This rate is sufficient to lower jitter in the less sensitive multi-media transmission. provide for critical medical data transmission in the For use in medical data transmission, however, it is U-home-care network. However, transmission of data rate inappropriate. at 272 Kbps over the ADSL uplink with a limit of 256 Kbps will cause the network to become congested and packet loss 2250 will occur. We must assume the use of different networks 2000 (IPv4/v6) for U-healthcare services. Doing so will not only 1750 1500 enhance the efficacy of telemedicine but also allow for the IPv6 TCP 120 Kbps Internet-based service of U-healthcare to reach most 1250 IPv6 TCP 64 Kbps 1000 IPv6 TCP 16 Kbps families with an inexpensive, widespread, and pervasive Delay (ms) 750 IPv4 TCP120 Kbps broadband network (ADSL). Unfortunately, when it is

500 IPv4 TCP 64 Kbps necessary to send high-definition, real-time medical IPv4 TCP 16 Kbps 250 streams (above 1544 bps uplink bandwidth), it cannot be 0 done using 3.5G or ADSL networks. There is an option of

16 32 64 128 192 256 320 384 448 512 using fiber, but using fiber has high monthly fees and it UDP data rate (Kbps) cannot be installed everywhere due to capacity issues. Fig. 10. Effect of delay in both UDP streams and TCP medical In addition, from the results in Section 5, we find that data transmission (ADSL). the values of IPv4/v6 which deal with the large traffic of 248 JOURNAL OF ELECTRONIC SCIENCE AND TECHNOLOGY, VOL. 11, NO. 3, SEPTEMBER 2013 medical data transmission are nearly in between. However, Household Indicators in Taiwan. [Online]. Available: the performance of IPv6 is still relatively good. Although http://www.find.org.tw/find/home.aspx?page=many&id=214 the majority of the current IPv6 is via IPv4 networks, and [8] H. Y. Yun, S. K. Yoo, D. K. Kim, and S. R. Kim, establishing a tunnel, dual stack routers or a translator leads “Performance evaluation of telemedicine system based on to increased overhead for the network, it does improve the multicasting over heterogeneous network,” in Proc. of the advantages of IPv6 that cannot be fully utilized (e.g. 27th IEEE Annual Conf. on Engineering in Medicine and simplifying header and route optimization). With the Biology, Shanghai, 2005, pp. 2175–2177. increasing usage in the All-IP age in the future, the [9] E. A. V. Navarro, J. R. Mas, and J. F. Navajas, “Analysis and U-home-care service built on the IPv6 network will have measurement of a wireless telemedicine system,” in Proc. of Pervasive Health Conf. and Workshops, Innsbruck, 2006, pp. advantages and will be established as an effective system 1–6. for a better class of U-home-care services. [10] J. F. Kurose and K. W. 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Konstantas, “Goodput Cheng-Chan Hung was born in Taichung in analysis of 3G wireless networks supporting m-health 1981. He received the B.S. degree from the services,” in Proc. of the 8th Int. Conf. on Department of Finance of Asia University in Telecommunications, Croatia, 2005, pp. 99–106. 2003 and the M.S. degree from the Asia [3] D. Komnakos, D. Vouyioukas, I. Maglogiannis, and P. University in 2006, both in computer & Constantinou1, “Performance evaluation of an enhanced communication engineering. He is currently uplink 3.5G system for mobile healthcare applications,” Int. pursuing the Ph.D. degree with the Department Journal of Telemedicine and Applications, doi: of Computer Science & Information Engineering, Asia University. 10.1155/2008/417870. His research interests include performance of computer networks, [4] R. S. H. Istepanian and N. Y. Philip, “Provisioning of QoS, and ubiquitous health-care system. medical quality of services for HSDPA and mobile WiMax in healthcare applications,” in Proc. of IEEE Annual Int. Shiow-Yuan Huang was born in Changhua in Conf. of on Engineering in Medicine and Biology Society, 1948. He received the B.S. degree from the Minneapolis, 2009, pp. 717–720. Department of Electrical Engineering, National [5] R. S. H. Istepanian, “WiMax for mobile healthcare Taiwan University (NTU) in 1969, the M.S. applications,” in Proc. of WiMax London 2007, London, degree in 1972, and the Ph.D. degree in 1984 2007, pp. 1–43. both from the Department of Electrical [6] R. S. H. Istepanian, E. Jovanov, and Y. T. Zhang, “Guest Engineering, NTU. Currently, he is a professor editorial introduction to the special section on m-health: with the Department of Photonics and Communication beyond seamless mobility and global wireless healthcare Engineering, Asia University. His research interests include connectivity,” IEEE Trans. on Information Technology in intelligent senseless-sensor monitoring infrastructure for Biomedicine, vol. 8, no. 4, pp. 405–414, 2004. healthcare, computer networks, web technology, fiber [7] Focus on Internet news and data. Investigation of Family communications, waveguide photoelectric, and information Broadband, Mobile and Wireless Applications and Demand - security.