=Paper=
{{Paper
|id=Vol-2647/paper13
|storemode=property
|title=Prospects for the Development of e-Health in Africa through the Iintegration of Optical Networks
|pdfUrl=https://ceur-ws.org/Vol-2647/paper13.pdf
|volume=Vol-2647
|authors=Boubacar Issoufou Djibo,Ahmed Kora
|dblpUrl=https://dblp.org/rec/conf/irehi/DjiboK19
}}
==Prospects for the Development of e-Health in Africa through the Iintegration of Optical Networks==
https://ceur-ws.org/Vol-2647/paper13.pdf
Prospects for the development of e-Health in Africa
through the integration of optical networks
Boubacar Issoufou DJIBO and Ahmed KORA
EST Niger, Niamey Plateau BP 307, Niger
ESMT Dakar, Dakar Liberté BP 10 000, Senegal
bidjibo@gmail.com, ahmed.kora@esmt.sn
Abstract. Telemedicine is a field that will be increasingly developed in African countries south
of the Sahara. These countries are generally characterised by low health coverage and a lack of
financial resources. The maturity of the optical transmission and access networks associated with
the development of connected objects in the field of health suggests the achievement of the goal
n°3 relating to health for all by 2030 defined by the United Nations Organization. Today, the
telemedicine model adopted in the developed countries cannot meet the African context de-
scribed above, as it requires fairly complex solutions not yet mastered by the Internet of Things
and a content-centric network approach (CCN). In this paper, we propose an integrated optical
transport and distribution solution based on Wave Length Multiplexing (WDM) and Passive Op-
tical Networks (PON) technologies to deliver health services to rural centres from urban referral
centres. We will use simulation to evaluate the performance of our proposal taking into account
the requirements of telemedicine.
Keywords: WDM (Wave Length Multiplexing), PON (and Passive Optical Networks),
ICT4SDG Information and Communication Technologies Four Achieving the Sustain-
able Development Goals), EKG (Electrocardiogram), EEG Electroencephalogram).
1. INTRODUCTION
In developing countries, particularly those south of the Sahara, access to health care is
a major issue. This situation is lived with acquittal and is manifested by a very high
infant mortality rate and the lowest life expectancy compared to other regions of the
world. This situation is due to the lack of specialist doctors in the villages and the in-
adequacy of medical devices (equipment) in the secondary health centers.
According to a study by the World Health Organization (WHO), in 2020, most of the
diseases in the world will be chronic, hypertension or cardiovascular diseases that re-
quire costly care and permanent medical monitoring by health specialists.
The evolution of information and communication technologies, in particular the emer-
gence of optical systems in telecommunication access networks, allows us today to face
these problems in the concept of telemedicine such as Internet of Things and a content-
centric network approach (CCN)[1][2].
Copyright © 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0
International (CC BY 4.0). IREHI-2019: International Conference on rural and elderly health Informatics,
Dakar, Sénégal, December 04-06, 2019
2
In this study, we will explore the levels of data quality inherent in transmission media,
particularly in optical networks, which are the best candidates for telemedicine data
transport.
In any case, the use of a full-scale test involving all dimensions would be necessary to
finalize the deployment of a new telemedicine infrastructure or its integration into an
existing infrastructure [3].
Thus, we propose at this level, a hybrid integration of the Wavelength Division Multi-
plexing (WDM) system and the Passive Optical Access Network (PON) capable of
containing the requirements of medical applications such as medical imaging and radi-
ology, demanding in terms of throughput, bandwidth and quality of service for the col-
lection of parameters from patients in rural areas for care by specialists [4][5].
The performance of the proposed solution will be evaluated using the parameters of
distance, signal throughput, transmitter power and the possibility of combining differ-
ent types of signals on the same medium. The bit-rate error rate (BER), the quality
factor (Q) and the aperture level of the signal eye diagram will be the elements of anal-
ysis.
2. WDM-PON ARCHITECTURE
This part of the document describes the technologies to be integrated for the transmis-
sion network and the access network for telemedicine applications.
2.1 WDM-PON Concept
Today, the extension of optical solutions in telecommunication access networks such
as WDM-PON and the use of advanced body sensor technologies (heart rate, body tem-
perature, electrocardiogram (EKG), electroencephalography (EEG), monitoring and as-
sistance to patients with chronic diseases, etc.) is a major challenge.), using wired and
wireless infrastructures, real-time data processing, interactive interfaces, allows the in-
terconnection of rural health points with the support of connected medical equipment
(connected objects) ranging from simple thermometers, scales, blood pressure monitors
for primary parameters to medical imaging equipment such as scanners, microscopes,
X-rays, magnetic resonance imaging (MRI), etc... It is therefore necessary to insist on
high quality, security and confidentiality of data to ensure correct interpretation of in-
formation and appropriate intervention by remote experts.
The choice of Wavelength Division Multiplexing (WDM) technology is based on the
possibility of simultaneously collecting the different parameters on the same medium
without the risk of interference between the different wavelengths dedicated to the dif-
ferent medical devices. This ensures greater dedicated bandwidth, quality of service
and security. Its association with the Passive Fiber Access Network (PON), which is a
"last mile" technology, is perfectly suited to the context of developing countries char-
acterized by recurrent disruptions in electrical power. However, it should be noted that
this solution requires transmitters and receivers for each of the medical equipment to
3
be connected, which will make the solution relatively expensive compared to traditional
PON solutions (EPON, GPON, 10GPON); however, the sensitivity to public health is-
sues in this part of the world sufficiently justifies these costs [6].
Fig 1: WDM-PON Network
2.2 Principle of WDM
Wavelength Division Multiplexing (WDM) is a technique that involves multiplexing
and transmitting multiple signals of different wavelengths over an optical fibre. Multi-
plexing takes place at the time of transmission through the multiplexer, while at the
receiving end it is up to the demultiplexer to decouple the signals through multi-band
filtering. The technique therefore consists of simultaneously transmitting several light
beams at different wavelengths, each of which represents a signal from the point of
view of the final equipment using it.
Thus, in order to multiplex several optical sources, it is necessary to modify their wave-
lengths using transponders. Each information stream is transposed onto a carrier by
amplitude or phase modulation. Multiplying equipment is usually passive equipment,
acting as multi-band filters that select signals in the corresponding wavelength regions.
This multiplexing technique further optimizes the bandwidth of the optical fibres [6].
The identification of the different channels is done using the carrier frequencies or as-
sociated wavelengths. The two are associated by the following empirical formula:
λ = C/F: (with λ; wavelength, C: velocity (or speed of light in a vacuum) and F: fre-
quency of the transmission channel).
There are two types of wavelength division multiplexing. When the wavelength spacing
is 20 nm, it is called CWDM. The advantage of CWDM is its cost. Indeed, because of
the large spacing left for each channel, it is not necessary to regulate the emission laser
in temperature. On the other hand, the limit is set at 18 unallocated channels where only
8 wavelengths at 10 GB/s are used in practice (1471 to 1611 nm). The second consists
of a densification of the wavelengths then called dense WDM (DWDM), more than 32
wavelengths are multiplied by a spacing of about 0.8 nm (100 GHz) or 0.4 nm (50 GHz)
or even 0.1 nm (12.5 GHz). It is therefore possible to combine up to 160 wavelengths
[7].
4
Six bands have been standardized by ITU-T, including C-band (conventional); 191.560
to 195.942THz (1 565 to 1 530 nm), a bandwidth close to 4 THz. It has the advantage
of being the least attenuated by the 0.2 dB/Km slope absorption and also the one whose
spectrum is amplified by EDFA (erbium doped Fiber Amplifiers. This makes this band
the most widely used over long distances [8].
For FTTH access links using GPON and WDM-PON technology, the O-band (1290
nm - 1130 nm) is used for uplink TDM streams with a linear attenuation of 0.3dB/Km.
It should be noted that the latest generation of "peak less" fibers has a slope linearity
over the entire spectrum from 1330 to 1530 nm with a linear attenuation of 0.2 dB/Km.
This results in a bandwidth greater than 35 THz [9]. Due to the increased bandwidth
requirements, L-band as well as Raman scattering amplifiers are also used [10].
Fig 2: WDM Multiplexing
3. THE SIMULATION
3.1 OptiSystem 7
The main simulation resource at our disposal for the evaluation of the proposed solution
is OptiSystem7, a software developed by a Canadian company Optiwave; Optical Com-
munication System Design Software, it allows engineers and researchers to design, sim-
ulate and analyze optical transmission systems. It is in fact a software that is based on
the principle of simulation in order to realistically order fiber optic communication sys-
tems. The simulation spectrum of OptiSystem can be extended by the possibility of
inserting user-made function blocks that can be easily integrated into the simulated sys-
tems. The virtual components in the library are capable of reproducing the same behav-
ior and effect as the real components. It should be noted that OptiSystem is currently at
version 16 [11].
3.2 Network requirement
After an in-depth analysis of the network requirements for telemedicine applications,
we have identified the critical conditions to simulate the solution to be proposed. Thus,
based on Table 1, we have a bit rate requirement for digital medical imaging "MRI"
5
applications at a distance of at least 1 Gbit/s, a bit error rate (BER) generally less than
1.10-10, a latency of less than 100 ms and an allowable packet loss rate of 0.1%.
Table 1: e-health network requirement
Service Type Functions Applications Rate BER La- Packet
tency loss
Digital Medicine Remote expertise Imaging trans- 1Gbps ‹10-10 100ms 0.1%
Imaging fer
Medical remote as- Remote radiol- 10Mbps ‹10-10 100ms 0.1%
sistance ogy
Visual Relation Remote consulting Web conference 10Mbps ‹10-10 100ms 0.1%
Remote expertise Visio confer- 1Mbps ‹10-10 100ms 0.1%
ence
Remote follow- Telemedicine Pulse, Temper- 1Mbps ‹10-3 ‹300m ‹0.5%
up ature, blood s
pressure
Medical Applica- EKG, EEG Data recording 2 Mbps ‹10-5 100ms ‹0.5%
tions
3.3 Network configuration
Despite the lack of infrastructure in sub-Saharan Africa, it is worth noting the countries'
efforts to develop optical backbones at the national level, which has facilitated the con-
nection of transport in the largest cities. The current problem is the connection of sec-
ondary towns and villages to broadband infrastructure. In the Republic of Niger, the
majority of these localities are located between 20 and 120 km from the national fibre
optic network, which is why we opted for WDM with PON at the end; this solves both
the problem of broadband service with WDM, but also the problem of energy that lives
with the acquittals in these areas with PON.
The choice also takes into account the need to optimize costs given the financing diffi-
culties in the areas to be served. We opted for low-power transmitters (CW-Laser at
0dBm) and 4 wavelength multiplexing in WDM to establish several simultaneous links
on the same medium (Digital Medical Imaging, visual link, Patient Monitoring, EKG,
EEG, etc...). In the remote health center to be served, we have selected devices con-
nected in GE, FE wired mode on the Optical Network Unit (ONU) and in wireless mode
via the IEEE WiGig 802.11ad standard [12].
Four 1Gbit/s streams each modulating a CW laser at 1550, 1551, 1552 and 1553 nm
respectively with 0 dBm power. The four signals are multiplexed and transmitted over
a 120 km long single-mode optical fiber. Reception takes place without amplification
after demultiplexing. Figure 1.3 shows the synoptic configuration of the solution.
6
Fig 3: WDM 4 waves block diagram
3.4 Simulation and results
Figure 4 shows the general architecture of our simulated connection with the OptiSys-
tem 7 software. Like any communication architecture, we can easily identify the trans-
mission part characterized by laser diodes, modulators and WDM multiplexer, the
transmission channel which is represented by a single-mode optical fiber and the recep-
tion part consisting of a set of receivers and optical amplifiers.
Fig 4: Four channels WDM Multiplexing
Once the assembly has been completed and recorded, the simulator must be started.
Once the compilation is complete, double-click on the spectrum analyzer at the output
of the multiplexer to observe the presence of the four carriers as shown in Figure 4.1.
7
Fig 4.1: Spectral representation of 4 channels WDM Mux out put
Figure 4.2 shows the state of the relative eye diagram. The associated table shows that
the quality Q-factor is only 5.01, the bit error rate (BER) is 2.10 -7 and the eye aperture
(height) is 15.10-7.
The optical power received before detection for each channel is of the order of -28 dBm.
Fig 4.2: Outflow eye diagram at 1550 nm
These characteristics do not guarantee efficient transmission in a telemedicine environ-
ment which is characterized by bit error rate requirements (10 -10) and a latency of less
than 100 ms. There is also a collapse of the 2U eye diagram and a signal shift over at
least 3 divisions.
8
Table 2: Eye Diagram Analysis without Amplifier at 1550 nm
In view of the requirements of telemedicine networks described above, such a link can-
not guarantee the efficiency of the services. Targeted possibilities include reducing the
distance from 120 to 100 km or adding an amplifier in the receiving chain. In view of
the infrastructure coverage constraint in the study area, we opted instead for maintain-
ing the distance and adding a 5 dB gain amplifier.
Figure 4.3 reflects the improvement induced by the addition of this amplifier. The im-
provement in Q-factor at 15.59, bit error rate at 4.10-55 (al-most zero) and eye height at
1.10-5 can be observed.
Fig 4.3: Outflow eye diagram at 1550 nm with 5dB amplifier.
The addition of a 5 dB amplifier in the receiving chain shows in Fig. 4.3 a maximum
eye aperture of more than 10U, the signal slip is reduced to less than one division and
the related Table 1.4 shows a bit error rate of the order of 10-55 (almost zero). These
parameters meet the requirements of telemedicine perfectly.
9
Table 3: Eye Diagram Analysis with 5 dB Amplifier at 1550 nm
Table 4: BER as a function of power with 5 dB amplifier
TX FIBER LENGTH Bit Error Rate
POWER (Km)
(dBm)
-20 10-1
-10 10-1
-5 120 10-1
-3 1,721.10-7
0 4.24.10.-55
Figure 4.4 shows the variation in bit error rates in relation to the variation in power. We
find relatively high bit error rates of the order of 10 -1 to 10-6 for transmit powers between
-20 and 0 dBm, but when the transmit power reaches +5 dBm, the bit error rate falls to
about 10-10, hence the need for a good choice of transmitters in such a system.
10
4. CONCLUSION AND PERSPECTIVES
The sensitivity and demand for telemedicine applications make fiber optics in transport
and access networks the best candidate in terms of transport infrastructure. Analysis of
Figures 4.3, 4.4 and associated tables clearly indicates the impact of optoelectronic
links on the rate, range, dispersion and quality of service of telemedicine applications.
Indeed, the association of WDM with the PON makes it possible to have optimized and
robust infrastructures in the context of the financial difficulties that characterize the
developing countries south of the Sahara. The optimization of these resources will
therefore provide an opportunity to extend broadband with a view to achieving sustain-
able development objectives through the use of ICTs (ICT4SDG), including objective
number 3, which concerns health for all issues.
Indeed, this integrated solution makes it possible not only to immediately initiate tele-
medicine practices in this disadvantaged region of the planet, but also to continue the
development of telemedicine through progressive extensions of connected health
equipment according to the availability of financial resources and existing infrastruc-
tures.
In terms of perspective, it would also be possible to experiment with dual-source laser
transmitters coupled to graded index multimode fibers, which will reduce investment
costs by eliminating multiplexers and the use of multimode fibers, whose costs are rel-
atively low compared with the single-mode fibers currently in use.
REFERENCES
[1] Daphné Guibert ; Jun Wu ; Shan He ; Meng Wang, CC-fog: Toward content-centric fog
networks for E-health Published in: 2017 IEEE 19th International Conference on e-Health
Networking, Applications and Services (Healthcom).
[2] Thierry O. C. Edoh Technical University of Munich Chair of Applied Software Engineer-
ing, Evaluation of a Multi-Tier Heterogeneous Sensor Network for Patient Monitoring –
The Case of Benin October 2016.
[3] National Plan of telemedicine deployment in France form GTT/SI edition Mars 2012
[4] J. Kani, "Enabling technologies for future scalable and flexible WDM-PON and WDM-
TDM-PON systems", to appear in IEEE Journal of Selected Topics in Quantum Electron-
ics", 2010 access: a review," J.Opt. Netw.
[5] A. Banerjee, Y. Park, F. Clarke, H. Song, S. Yang, G. Kramer, K. Kim, and B. Mukherjee,
"Wavelength division-multiplexed passive optical network (WDM-PON) technologies for
broadband/2012
[6] A.S.Samra H.H.Soliman Hanan Mohamed Ali Khatab Analysis of WDM Passive Optical
Network (WDM-PON) Performance using CWDM. International Journal of Electronics
and Communications, ISSN: 2051-5219, Vol.14, Issue.1 stage 2 (NG-PON2),”J. Lightw.
Technol., vol. 31, no. 4, pp. 587–593, 2/2013.
[7] O S Sunish Kumar D. Meena A novel analytical study of different channel allocations and
FWM efficiencies in optical WDM systems 9-12 dec 2012 IEEE int. conf on fiber and
photonics
[8] ITU-T Recommendation on CWDM G.695 2015-01-13 15 11.1002/1000/12362 edition6
11
[9] P. P. Iannone et al., "A 40Gb/s CWDM-TDM PON with a cyclic CWDM Multiplexer /de-
multiplexer", ECOC, Sep. 2009 (2002) The IEEE website. [Online]. Available:
http://www.ieee.org/
[10] Y. Yamamoto Water-free pure silice core fiber and its stability against hydrogen ageing;
Electronics letters volume 46, issue 22, sept 2016
[11] Paula Pamavolala Latapou, Bridging the digital divide in Tonga through a sustainable
multi-tenancy broadband infrastructure: Are we ready? IEEE Conference 12-14 March
2018 Milan, Italy.
[12] Frederic Surre ; T. Binh Pham ; Han Cheng Seat ; Olivier D Bernal 2015 IEEE SENSORS