detecon technical final report part1-1

Member of

Final Report

Part 1: Technical

Study on Low Cost VSAT Technologies and Licensing Regimes

for

The World Bank

and

African Virtual University

Detecon International GmbH

Oberkasseler Straße 2

53227 Bonn, Germany

Study on Low Cost VSAT Technologies: Final Report

Detecon International GmbH, March 2003 - i - (Final Report Technical Part)

Table of Content

1 Executive Summary 1

2 AVU Communication System Requirements (initial) 3 2.1 AVU Service Requirements 3 2.2 AVU Network Topology 4

3 Review of Ku-Band Satellites 6 3.1 General Remarks 6 3.2 Identification of suitable Ku-Band Satellites 7 3.2.1 Existing Ku-Band Satellites 7 3.2.2 Planned Satellites 11 3.2.3 Two Overlapping Coverages 12 3.3 Conclusion 14

4 Feasibility of the Ku-Band 15 4.1 Use of the Ku-Band 15 4.2 Comparison of Link Efficiencies 19 4.3 Availability and Costing of Ku-Band Space Segment over Africa 20 4.3.1 Availability 20 4.4 Costing of Space Segment 20 4.4.1 General Situation 20 4.4.2 Actual Pricing for Ku-Band Transponders 22

5 Revised AVU Requirements 23 5.0 Detailed Traffic and Service Requirements 23 5.1 23 5.1.1 Learning Center Requirements (LC) 23 5.1.2 Center of Excellence requirements 24 5.1.3 Houses of Parliaments 25 5.1.4 Service descriptions 26 5.1.4.1 Internet Access 26 5.1.4.2 Video on-line courses 27 5.1.4.3 Video feeding from CE 27 5.1.4.4 Video conference 28 5.2 Analysis and Synthesis of AVU Traffic Requirements 28 5.2.1 Traffic Flow Requirements 28 5.2.2 Traffic bandwidth requirements 30 5.2.3 Requirements for the Space Segment 32 5.3 First Design of a AVU Network 36


©Detecon International GmbH, March 2003 - ii - (Final Report Technical Part)

5.3.1 General Remarks 36 5.3.2 Baselines for the Network Design 40 5.3.3 Generic network design 42 5.3.4 Outbound System 43 5.3.5 Inbound System 45 5.3.6 Video Conference Network 52

6 Optimisation of the VSAT Network Error! Bookmark not defined.53 6.1 General Remarks Error! Bookmark not defined.53 6.2 Full Deployment Error! Bookmark not defined.53 6.3 Partial Deployment Error! Bookmark not defined.60

7 AVU Network Design Error! Bookmark not defined.70 7.1 Technical specification of the AVU VSAT systemError! Bookmark not defined.78 7.1.1 Hub system Error! Bookmark not defined.79 7.1.2 LC terminal Error! Bookmark not defined.80 7.1.3 CE Terminal Error! Bookmark not defined.80 7.1.4 PA terminal Error! Bookmark not defined.81

8 Cost Assessment Error! Bookmark not defined.83 8.1 Estimated Hardware Cost Error! Bookmark not defined.83 8.2 Cost Assessment for the Spacesegment.Error! Bookmark not defined.86

9 Sensitivity Analysis Error! Bookmark not defined.87 9.1 General Remarks Error! Bookmark not defined.87 9.2 VSAT´s with 1.8m Antenna Error! Bookmark not defined.87 9.3 VSAT´s with 2.4m Antenna Error! Bookmark not defined.91 9.4 Cost Assessment for the 2.4m AntennaError! Bookmark not defined.94

10 Recommendations Error! Bookmark not defined.98


Detecon International GmbH, March 2003 - 1 - (Final Report Technical Part)

1 Executive Summary

The African Virtual University (AVU) aims to become a reputable and internationally recognized African Institution for tertiary education contributing to the continents capacity building efforts.

The development strategy of AVU encompass three phases:

- Phase one (1997-1999) The “proof of concept” stage using the expertise and facilities of the World Bank with the support of various African Universities

- Phase two (1999-2002) Establishment of 31 AVU Learning Centers at partner universities in 17 countries

- Phase three (2002-2007) To extend to 150 Learning Centers in all 53 African countries To establish AVU´s own communications infrastructure i.e. hub, studio and VSAT at its headquarters in Nairobi or elsewhere in Africa.

To analyze the feasibility of the required satellite based network the World Bank awarded a study to Detecon International GmbH with regard to the technical and regulatory aspects of a low cost VSAT network for AVU.

The study was initially just limited to the conditions of phase two (31 LC´s in 17/22 countries), but during extensive discussions with the AVU management it turned out that the conditions for phase three should apply. In addition AVU intends to introduce beside the intellectual (university) program a so called partnership program with the parliaments in all African countries.

The enlargement from a sub Saharan coverage to a pan African coverage and the interconnectivity requirements calls for a solution based on single wide beam coverage of total Africa including the islands. Whereas the technical part of the study could be adopted to the new requirements the regulatory part had to be limited to the original list of 22 countries.

The results of the study are contained in a two part document one dealing with the technical feasibility analysis and the other one with the regulatory/licensing regimes.


©Detecon International GmbH, March 2003 - 2 - (Final Report Technical Part)

The technical approach selected for AVU is based on existing C-band satellites and the use of VSAT´s with 2.4m antenna. The optimization has shown that a hub of about 6.5m would be sufficient to handle the traffic. Within a sensitivity analysis the cost of the spacesegment has been investigated as a function of the number of active PC´s in the network. The Internet access traffic is the main cost driver for the spacesegment in all analyzed network configurations.

The technical feasibility of the envisaged VSAT network has been proven. The availability of sufficient spacesegment capacity could not be verified due to the actual political situation resulting in a very poor responsiveness of most of the satellite operators.



2 AVU Communication System Requirements (initial)

2.1 AVU Service Requirements

AVU desires to upgrade its broadcast network to feature rich interactive network.

The satellite-based network should support at least the following services:

Video Broadcasting (DVB/MPEG2/4 or other)

Video Streaming (DVB-IP)

High Speed Internet Access (two-way)

Multicast Data Downloads

The following services are considered as optional but highly desirable:

Voice/telephony (VoIP)

Videoconferencing (also Web based)

These services should be handled in the Hub and connection to the public networks is desirable.

For some Learning Centers and the NCC the possibility for a single hop interconnectivity should be provided


©Detecon International GmbH, March 2003 - 4 – (Final Report Technical Part)

ForwardLink

DVB-S

Return Link

DVB Modulator Demodulator

DVB MUX Router

HUB

InternetBackbone

DVB In

LearningCenter

LearningCenter

NCC Nairobi

LAN

LAN

LAN

Network Control Center

PSTN

Forward Link (Broadcasting)

Returnlink LC to Hub

Interconnectivity (LC to LC)

Connectivity: LC to Hub

Connectivity: LC to HubandLC to LC or NCC

Possible Hub Locations:

South AfricaSenegalGhanaNigeriaMaroccoorEurope

LearningCenter

ForwardLink

DVB-S

Return Link

DVB Modulator Demodulator

DVB MUX Router

HUB

InternetBackbone

DVB In

LearningCenter

LearningCenter

NCC Nairobi

LAN

LAN

LAN


PSTN


Returnlink LC to Hub

Interconnectivity (LC to LC)

Connectivity: LC to Hub

Connectivity: LC to HubandLC to LC or NCC

Possible Hub Locations:


LearningCenter

2.2 AVU Network Topology




Return Link (LC to Hub)

Interconnectivity: LC to LC or NCC Possible HUB Locations:


Connection to SAT 2/3

Topology cont.


Return Link (LC to Hub)

Interconnectivity: LC to LC or NCC Possible HUB Locations:


Connection to SAT 2/3

Topology cont.



3 Review of Ku-Band Satellites

3.1 General Remarks

The availability of high power Ku-band satellites in Europe, the Americas and Asia has triggered the development of low cost ground equipment. Specifically the mass market for DTH receiving equipment has resulted in extreme low prices even for the relative new digital receivers. But also the VSAT market for interactive two-way communication has benefited from the powerful Ku-band satellites. These satellites can be characterized by a high EIRP (typically > 48 dBW) and still acceptable G/T’s ( > 6 dB/K) This performance could only be achieved by the limitation to relative small coverage zones compared to the initial global or hemispheric coverages realized by the early C-band satellites. The restriction to much smaller service areas resulted in significantly higher antenna gains onboard the satellites.

Furthermore the restrictions of the Radio Regulations as applicable to the C-band have been lowered for the Ku-band to allow the realization of the DTH or BSS services.

However the Ku-band has also a serious disadvantage compared to the C-band as it is more affected by rain attenuation. That is why for long the C-band was the preferred solution for the tropical and sub-tropical regions.

The availability of more efficient transmission principles and compression techniques made the Ku-band also for rainy regions attractive. But still it took some time that the major satellite operators started serving the tropical rain belts like Central Africa with Ku-band satellite capacity.

To serve the whole African continent with a single wide beam seems not to be feasible as the antenna gain of the satellite would be too low to provide a sufficient high EIRP and G/T. In addition the rainy areas are further degrading the overall budget.

So it is no surprise that a lot satellite operators concentrated their engagement to relative small areas by using high gain spot antennas (e.g. South Africa or West Africa). Only a few satellite operators decided to provide some coverage areas, which serve or will serve a major part of the sub-Saharan community of countries.



The review of the existing and the planned Ku-band satellite capacity for the sub-Saharan counties is summarized in the following section.

3.2 Identification of suitable Ku-Band Satellites

All existing satellites of the major satellite operators have been analyzed with regard to a single widebeam covering those sub-Saharan countries being of interest for AVU. The first analysis of the retrieved data is not very encouraging. None of the existing satellites will provide a single widebeam coverage. There are two satellites one from EUTELSAT (W4) and the other one from PANAMSAT (PAS10) providing service areas which cover the major part of the sub Saharan countries. There is another satellite planned by EUTELSAT (W3A), which would provide some better coverage as compared to the two existing ones. Several satellite operators however are providing spotbeam coverages of several African regions or countries like South Africa or West Africa.

A more detailed analysis of the different satellite opportunities is given in the following section.

3.2.1 Existing Ku-Band Satellites

PAS 10 (PANAMSAT)

The coverage of PAS 10 shows a relative good coverage of the sub Saharan countries, but due to the orbital position of PAS 10 (68.5° E) the north west part of Africa is out of the visibility of the satellite (Senegal and part of Mauritania). For other regions the coverage does not provide sufficient power or G/T (parts of Mali and Niger).

The available the EIRP in the rainy areas reaches 44 to 45 dBW and the G/T could be between –1 dB/K to –2 dB/K. In the north west corner of the coverage the situation is worse but the attenuation by rain is not so high.



PAS 10 Coverage Source: Panamsat



EUTELSAT W4

W4 satellite of EUTELSAT shows also a relative good coverage of the sub Saharan countries except for South Africa, Namibia and major parts of Ethiopia, Niger, Mali and Mauritania.

In the central part of the coverage including the rainy zones the EIRP reaches about 44 dBW. The shown edge of coverage EIRP of 36 dBW is quite low and would not allow efficient use of the satellite resources.

The G/T performance as shown on the next page is also critical at the edge of coverage (about – 5 dB/K). In the central part of the coverage the G/T of 2dB/K is sufficient.

Source: EUTELSAT



EUTELSAT W4 Spotbeam The spotbeam shown below is typical for the performance of regional spotbeams. The power is relative high (>50 dBW) and also the G/T is excellent. The drawbacks are the small regions covered and the need to use several satellites and transponders to serve the envisaged coverage zone. It seems more than doubtful that the use of multiple spotbeams would fit in a low cost scenario.

3.2.2

Source: EUTELSAT



Planned Satellites

EUTELSAT W3A

EUTELSAT plans to launch the W 3A by mid 2003 (?). The expected coverage seems to be the best of all reviewed so far. But also this satellite will not cover all the countries of interest for AVU. Again the northwest region with Mauritania, Senegal and Mali are not covered or are at the extreme edge of coverage. The same is valid for Ethiopia. The EIRP in the central rainy regions is not very high (only 44 to 45 dBW) and in some parts of DRC even worse. The G/T is generally

relative low due to the large coverage area (between –1 and –6 dB/K).

Source: EUTELSAT



3.2.3 Two Overlapping Coverages

The most efficient possibility to cover the full sub Saharan region with Ku-band satellite capacity would be the use of two coverages overlapping such that with only two satellites the region can be covered. The perfect match with PAS 10 would be the use of PAS 1R. The Ku-band coverage serves exactly that part of the sub Sahara that is not covered by PAS 10. In addition the relative low elevation angles in the northwestern region could be avoided. The RF-performance of PAS 1R is similar to that of PAS 10. The orbital position of PAS 1R is 45° W. The combined coverage is shown on the next page.

PAS 1R coverge Source: Panamsat



The combined coverages of PAS 10 and PAS 1R show an excellent service area over nearly the full African continent. The major disadvantage of such a two-satellite solution would be the double cost of the spacesegment (for the forward link) and the double cost for the hub function (at least for the RF part).

Source Panamsat



3.3 Conclusion

The actually existing Ku-band satellites do not provide a single widebeam coverage of the sub Saharan region. Also the planned satellites will not provide the necessary coverage with a single wide beam. In case the Ku-band should be used for the AVU VSAT network more than one satellite has to be used. The combination of PAS 1R and PAS 10 would provide an excellent coverage of the total sub Saharan region. The major disadvantage of such a solution would be the additional costs of the spacesegment and the higher costs of the hub functions if two satellites have to be used.

Another possibility would be to use one of the best suitable satellites like EUTELSAT W3A and to serve those countries not placed well within the coverage by other means as for instance by terrestrial links.



4 Feasibility of the Ku-Band

4.1 Use of the Ku-Band

The configuration of the existing as well as the planned Ku-band satellites constitute a major problem for any cost efficient use of this frequency band. That what makes the use of the Ku-band so attractive namely the high power (EIRP) and the good G/T are missing for the satellites covering large areas such as the sub Saharan region. In addition the link degradation by the heavy rain is further contributing to the negative impacts.

The classification of the rain climatic zones is done by the ITU and is shown in the next Figure.



The rain intensity is classified by the ITU into the following zones:

A, B, C, D, E, F, G, H, J, K, L, N, P, Q

A is the lowest and P is the highest rain rate.

It can be seen from this map that several countries in the sub Saharan region are belonging either to rain zone N or P.

For the link budgets the rain zone P will be used.

Another important factor in the link budgets is the required availability. In the diagram the attenuation vs. availability is given. Typically the availability is given in % for the average year. 99% availability means a downtime of 87.66 hours per year. The 99% for the average year corresponds to about 97.1 % for the worst month corresponding to 20.8 hours downtime.

Rain Attenuation vs AvailabilityFor Rain Zone P at 12.6 GHz

0

2

4

6

8

10

94,0 95,0 96,0 97,0 98,0 99,0 100,0

Availability in % (average year)

Rai

n A

ttenu

atio

n in

dB



The attenuation by the precipitation is not the only effect. The attenuation of the electromagnetic waves by the raindrops increases also the noise floor of the receiver. In the next two Figures the total effect is shown for the C-band and the Ku-band. The noise figure of the receiver is assumed to be 1 dB.

The comparison of the rain effect for the two frequency bands shows a

Rain AttenuationC-Band (4GHz)

0,000,05

0,100,15

0,200,25

0,300,35

A C E K N P

Rain Zones

Atte

nuat

ion

in d

B

98%99%99,50%

Availability

Rain AttenuationKu-Band (12.6 GHz)

0123

4567

A C E K N P

Rain Zones

Att

enua

tion

in d

B

98%99%99.5%

Availability



significant degradation for the Ku-band at the higher rain rates (Zones N and P).



4.2 Comparison of Link Efficiencies

For the C-band and the Ku-band the link efficiencies can be compared without taking into account any real traffic. The comparison below takes into account some realistic figures for the EIRP, G/T and the VSAT antenna diameter. The comparison is done for rain zone P and a typical noise temperature of 60° K. The antenna diameters of the VSAT’s reflect the figures, which could still be considered as low cost versions. It can be clearly seen that in the forward link the Ku-band with an EIRP of 8 dB higher than the C-band shows at the end 3 dB lower efficiency. The situation is similar for the return link.

Band Link EIRP sat G/T sat Loss Atm. Loss Rain att G/T degr. E/S antenna Gain Rx Gain Tx Link balance

dBW dB/K dB dB dB dB m dBi dBi dB

C Forward 38 196,30 0,44 0,03 0,05 2,4 38,07 -120,75

Ku Forward 46 206,56 1,78 3,52 3,77 1,8 45,65 -123,98

C Return -5 200,14 0,57 0,16 2,4 41,92 -163,95

Ku Return 1 207,63 2,06 4,31 1,8 46,72 -166,28

Link balance forward link: EIRP sat - Loss - a tm.loss - rainatt - G/Tdegr + GainRx

Link balance return link: G/ sat - Loss - atm.loss - rainatt + Gain Tx

Study on Low Cost VSAT Technologies:Final Report


4.3 Availability and Costing of Ku-Band Space Segment over Africa

4.3.1 Availability

The availability of Ku-band capacity over Africa seems to be no major problem at the time being. Several satellite operators are providing capacity with spotbeams over several regions in Africa. The demand for single widebeam capacity seems not to be as high as that for the spotbeams due to the drawbacks mentioned earlier. For the most promising satellites (PAS10 and PAS1R) sufficient capacity would be available just now and in the near future. There are additional satellites planned providing either additional spotbeams or larger coverages. Examples are:

EUTELSAT W3A

Hellassat (spotbeam)

Rascom (several spotbeams)

Other satellite operators may decide to point their spots in case of sufficient demand to Africa.

4.4 Costing of Space Segment

4.4.1 General Situation

The London satellite exchange compiled since mid 2001 the prices of transponder fractions in the Ku-band and the C-band. This survey is also done for the different regions of the world. A summary is given below.

The e-sax index is compiled on the basis that:

- The lease is of one (1) MHz with an initial contractual commitment of 3 years (Prices shown in US$ / MHz / month).

- The capacity is non-preemptible and non-restorable. Pricing information is wholesale. The index presents a weighted average of the different

operator prices on a transponder per transponder basis in function of the main continental cross connection. Even partial coverage by a given transponder of a continent is considered as a possible connection for the designated zone. Today the table takes into account 76% of the world geo fleet. Only commercial



operational satellites have been considered. Satellites in inclined orbit are not included in the index. The tables use abscissa axis as downlink locations and ordinate



4.4.2 Actual Pricing for Ku-Band Transponders

The price quotation of Panamsat is as follows:

10 MHz capacity

Leasing period 3 years

non-preemptible

4000 U$/MHz/months (standard commercial conditions)

There may be a chance to get a 20% reduction for the specific application but this would be subject to contract negotiations.

For less than 10 MHz the price would be slightly higher (~10%) and for more capacity the price would further decrease.

In case AVU would accept a preemtible condition the price would drop to about 2800 U$/MHz/month.

Prices for the future W3A is not yet released, but it can be expected that EUTELSAT will not deviate significantly from those of its competitors.



5 Revised AVU Requirements

The following traffic and service requirements were collected during the workshop with AVU after the interim presentation on 14.3.03 in Nairobi.

These requirements have been agreed and confirmed by AVU during a meeting on 17.3.03 and further detailed during the final presentation on 21.3.03 in Nairobi.

5.1 Detailed Traffic and Service Requirements

The AVU network can be divided into two different networks:

the e-learning “intellectual” network and the Houses-of-Parliaments network.

All planned AVU sites can be divided into the following three groups:

LC Learning Center

CE Center of Excellence

PA Houses of Parliaments

The e-Learning network of AVU consists of the LC and CE type of sites. During the next three years the AVU plans to establish 100 LC´s and CE´s.

LC´s and CE´s will be established on the campus and under the umbrella of local Universities as member institutes of the AVU organization. The university staff will be responsible to manage and operate the LC´s and CE´s.

The Parliament network shall be established during the next 18 month and shall include the parliament sites of all 53 African countries.

5.1.1 Learning Center Requirements (LC)

Each learning center shall be able to receive video transmission streams

(broadcast of learning content):

12 hours during day-time for on-line viewing:

1 channel (French & English) for degree courses

1 channel for short curses



from year 3 additional channels may be required

12 hours during night time for off-line viewing:

1 channel for off-line video content degree courses

1 channel short courses

At each LC site a WEB-CT learning content server will be installed (by AVU). All WEB-CT content needed for the interactive computer assisted learning will be mirrored (“content synchronization”) to that server from the central WEB-CT AVU content server, located either at the AVU hub or at any other site connected to the Internet backbone. The amount of data for one semester and one course is about 150 MByte. These data can be delivered before the beginning of each semester to each of the appropriate WEB-CT servers by a special “synchronization” process.

Organisation:

8 degree courses at first year, 24 at year 2 and 48 at year 3

4h per student&week&course are spend in the LC (1h live content, 2h WEB-CT local work, 1h Internet Access)

10 Short courses (4h per student&week)

Internet Access

At each learning center up to 100 PC will be available in an “Internet cafe” like environment with direct access to the Internet. Due to poor Internet access in most of the African countries these PC´s will be heavily used by Internet users (WEB browsing, e-mail. Chat, file transfer). Together with the e-Learning PC’s within the other LC classrooms there may probably be 100 PC’s per LC continuously attached to the Internet with active sessions. One PC will require in average 8kbps downstream and 2 kbps upstream for the Internet access.

5.1.2 Center of Excellence requirements

A “Center of Excellence” is an AVU member university, operating an AVU Learning Centre and in addition producing and providing learning content to the AVU organization.

It is planed to establish 8 CE. The CE should be located at the universities

of:



Dar Es Salaam, Tanzania

Addis Ababa, Ethiopia

Dakar & St.Louis, Senegal

Marrakech, Morocco

Kigali, Uganda

Cotonou, Benin

Nouakchott

The AVU HQ in Nairobi will also get the status of a CE

The CE member list may be modified in the future, but with very high probability the following countries will not be included in the CE list: Congo, DRC-Congo, Cameroon, Somalia and Sudan.

The basic traffic and service requirements of each CE are the same as of an usual AVU LC (see above)

Additionally to the usual LC a CE has to meet the following traffic and service requirements:

Each CE shall be able to provide live video feeds to the AVU network, but only one CE will transmit a video stream at a time.

As option the CE should be able to establish videoconferences directly between each other. The network should provide transmission capacity for four videoconference simplex channels, so that videoconferences of up to four sites as 1:1, 1:2, 1:3 ore 2 times 1:1 sessions could be established. During a live video content transmission the CE will not participate in a videoconference.

5.1.3 Houses of Parliaments

All African Houses of Parliaments (53 sites, including the African Islands) should be connected by a special AVU sub network. At each PA site communication and learning centers similar to small AVU LC at the AVU partner universities shall be installed. The Parliament LCs (PA) will contain 50 PC´s in a network together with WEB-CT content server and live video content display (and storage) equipment.



Especially for the PA the AVU will provide a number of so called “short courses” and other special courses. The full courses program for all PA will contain a total of about 10h per week live video content, transmitted in parallel to the other AVU live video learning content, mostly during the usual working hours.

30% of the PC’s at the PA LC sites will require Internet Access at the same time, mostly during working hours. Requirements per PC will be about 8kbps downstream and 2kbps upstream.

The Parliaments shall be able to establish videoconferences directly between each other. The network should provide transmission capacity for four videoconference simplex channels, so that videoconferences of up to four sites could be established as 1:1, 1:2, 1:3 ore 2 times 1:1 sessions.

In addition it should be possible to connect up to 10 additional sites by audio conference into a videoconference.

5.1.4 Service descriptions

5.1.4.1 Internet Access

The Internet access is a straight star topology: all Internet user of the AVU network will use either Internet services of the hub servers or services attached to the Internet backbone. There is no requirement for any interconnection between the AVU sites.

Each PC attached to the internet requires a datarate of 8kbs downstream and 2kbps upstream.

The LC’s/CE’s shall be able to handle the required Internet access capacity for 100 PC’s used in parallel. So each LC/CE requires from the network a downstream capacity of 800 kbps and an upstream capacity of 200 kbps.

As the LAN of each LC/CE is already acting as traffic concentrator it can be assumed, that no further concentration of traffic within the VSAT network could be realized. Thus the required network capacity for the LC/CE Internet access of the whole network will be about 80 Mbps downstream and 20 Mbps upstream for all 100 LC’s and CE’s.



The Internet access requirements of a PA site are considerably lower and will only be 120 kbps downstream and 30 kbps upstream. The total required Internet access capacity of all PA’s is 6,4 Mbps downstream and 1,6 Mbps upstream.

The overall required network capacity for Internet Access will directly depend on the number of LC/CE sites in operation and on the number of attached PC’s.

5.1.4.2 Video on-line courses

The learning content will be delivered partially as live video streams. The video streams are delivered as IP multicast video streams with 1Mbps data rate from the AVU hub to the LC, CE and PA.

The bandwidth requirement of 1Mbps is based on the use of state of the art video compression techniques, supporting MPEG4 and/or WindowsMedia9 codecs. Appropriate systems are already on the market (WM9) or will be available within the next month (MPEG4).

During the first year two video channels: one for each language should be provided. The channel capacity is sufficient to transmit all required content. From the third year six video streaming channels are needed to broadcast all live degree and short course content of the LC/CE.

For the PA´s an additional live video channel may be needed.

The total amount of required datarates from AVU hub to the remote sites is in the first year 3 Mbps and from the third year onward 7 Mbps.

5.1.4.3 Video feeding from CE

Each CE should be able to transmit to all other LC/CE within the AVU network one live video stream with 1Mbps.

The live video stream will be transmitted from the CE to the hub and from the hub as one of the 2…7 live video streams to all other LC´s/CE´s.

Only one CE at a time will send a live video stream to the hub.



5.1.4.4 Video conference

The subnetwork of the Houses of Parliaments should provide videoconference services for up to 4 participants (as 1:3, 1:2, 1:1, 2x 1:1 VC) with 256kbps per video stream. In addition up to 10 PA sites should be able to participate by Chairman enabled audio channels in the video conference (for these sites the following is required: video: receive only, return channel: audio)

5.2 Analysis and Synthesis of AVU Traffic Requirements

In the following chapter the traffic requirements of the AVU will be analysed to get information about the quantitative and qualitative traffic flow in the network. Based on this analysis a draft network design can be done.

5.2.1 Traffic Flow Requirements

The traffic flow scheme shows the summarized AVU traffic requirements as traffic directions of different AVU services between the hub and the terminals.

As it can be seen from this scheme, AVU requires dedicated hub to/from terminal traffic (Internet Access and Video streaming) but also requires inter terminal (meshed) traffic (Video conference between CE’s and PA’s and Video feeds from CE’s to all LC’S/CE’s.

The inter terminal traffic requirement (any-to-any video conference) is a very strong (killer) requirement for selection of an appropriate satellite platform. As the PA and CE are spread across the whole African continent a fully meshed traffic flow can only be assured in case of using an all-African satellite coverage. Such coverage can be provided only with a C-band hemi beam or a C-band global beam. All other available satellite beams on the market actually and in the near future) will not provide an all African coverage.



5.2.2 Traffic bandwidth requirements

The table below shows the traffic requirements for each type of AVU site and each type of service, used by or provided to the site or terminal:

AVU traffic requirements per terminal type

Terminal type

Service Number of Terminals

Receive (Mbps)

Transmit (Mbps)

Remarks

LC Internet 0,8 0,2 100 PCs per LC for Internet with 8kbps down and 2kbps up

Courses (streaming)

2 1x degree courses and 1x short course with 1Mbps

Total 100 2,8 0,2 CE Internet 0,8 0,2 Courses 2 1 Videoconf. 0,768 0,256 1 TC and up to 3 RX Total 9 3,568 1,2 VC and VideoFeed

could not be at the same time

Parl. Internet 0,12 0,03 30 PC per Parl. Courses 1 Videocon 0,768 0,256 One VC transmission

and up to 3 receives Audio 0,02 Or instead of VC one

Audio transmission Total Internet&Audio 53 1,888 0,286

The “Total” lines indicate the required maximum receive and transmit capacity of the given terminal type.



The router of the given terminal type should at least be able to handle the required traffic volume. The carrier system of the AVU network should at least be able to transport the required transmit capacity from each terminal.



The following table classifieds the different traffic flows by traffic type and traffic direction and gives a first rough total network traffic estimation:

Total AVU traffic requirements per network

Service Traffic direction

Traffic type

Traffic amount within the network in MBps

Remarks

Internet Downlink

Hub>LC/CE PtP 80 800 kbps per terminal, 100 terminals

Internet Downlink

Hub>PA PtP 6,4 120 kbps per terminal, 53 terminals

Internet uplink LC/CE>Hub PtP 20 200 kbps per terminal Internet uplink PA>Hub PtP 1,6 30 kbps per terminal Live Video streams

Hub>LC/CE PtMP 4 2 streams at each language per 1MBps

Live Video streams feeding

CE>LC/CE PtMP 1 One stream

Video conference

CE>CE PtMP 1 Up to 4 VC streams per 256kbps

Video conference

PA>PA PtMP 1 Up to 4 VC streams per 256 kbps

Total traffic Whole network 115 Hub>

Terminals 90,4

Terminals>Hub 21,6 Inter Terminals 3

5.2.3 Requirements for the Space Segment

The requirements as presented above need some careful analysis with regard to the proper selection of the space segment. As already presented above the available as well as the planned Ku-band satellites do not provide any pan-



African coverage. The specific interconnectivity needs of the parliament houses require single hop connections between the involved earth stations. Any double hop would seriously affect the acceptance of the envisaged videoconference service due to the additional latency.

A realization with two or even more spotbeams would also significantly increase the cost the hub function as most spotbeams can be found on different satellites at different orbital locations.

Based on the above requirements only satellites providing a single beam coverage of the African continent are considered in the further analysis.

A careful analysis of available and planned satellites indicate that there are only some C-band satellites, which meet the requirements.

Suitable satellites seem to be the following:

Newskies: NSS-7(21.5°W) or NSS-703(57°E)

Intelsat 905 (24.5°W)

901 (18°W)

904 (60°E)

907 (27.5°W)

10-02 (1°W) planned

As we were unable to receive some quotation from Intelsat or Newskies we have taken NSS-7 and IS 901 as possible candidates. The family of IS satellites is very similar in the C-band hemispherical performance. The coverages are shown on the next pages.



Transmit Coverage

Contours Shown dBW

40.0

39.0

38.0

37.0

36.0

35.0

Remarks

The 37 dBW contour line represents the nominal edge of coverage. For operation beyond this contour, co-channel interference levels should be assessed on a case by case basis.

Elevation Angles Shown at 0, 5 and 10 Degrees

NSS-7 (21.5°W)

Transmit Coverage

Contours Shown dBW

40.0

39.0

38.0

37.0

36.0

35.0

Remarks



Transmit Coverage

Contours Shown dBW

40.0

39.0

38.0

37.0

36.0

35.0

Remarks



NSS-7 (21.5°W)



Total TranspondersC-Band: 72 (in equiv. 36 MHz units)PolarizationC-Band: Circular – Right Hand or Left Hande.i.r.p.Global Beam: 31.0 up to 35.9 dBWHemi Beam: 36.0 up to 41.0 dBWZone Beam: 36.0 up to 44.1 dBWUplink FrequencyC-Band: 5850 to 6425 MHzDownlink FrequencyC-Band: 3625 to 4200 MHzG/T (C-Band)Global Beam: -11.2 up to -5.6 dB/KHemi Beam: -8.0 up to -1.6 dB/KZone Beam: -7.4 up to +5.9 dB/KSFD RangeC-Band: -89.0 to -67.0 dBW/m²

Intelsat 901 (18°W)

Total TranspondersC-Band: 72 (in equiv. 36 MHz units)PolarizationC-Band: Circular – Right Hand or Left Hande.i.r.p.Global Beam: 31.0 up to 35.9 dBWHemi Beam: 36.0 up to 41.0 dBWZone Beam: 36.0 up to 44.1 dBWUplink FrequencyC-Band: 5850 to 6425 MHzDownlink FrequencyC-Band: 3625 to 4200 MHzG/T (C-Band)Global Beam: -11.2 up to -5.6 dB/KHemi Beam: -8.0 up to -1.6 dB/KZone Beam: -7.4 up to +5.9 dB/KSFD RangeC-Band: -89.0 to -67.0 dBW/m²

Intelsat 901 (18°W)



5.3 First Design of a AVU Network

5.3.1 General Remarks

The business objectives of AVU related to the network were indicated by the AVU

as:

Cost effectiveness:

The biggest cost element of the AVU network is recently the (satellite) bandwidth cost. The network related costs per learning unit should be decreased significantly to achieve the AVU goals.

Low entry barrier:

The most important barrier to expand its Learning Center network is today for AVU the relatively high cost of the required LC equipment.

Scalability and flexibility:

The network should be easily expandable introducing additional sites and services.

The network design process is based on following assumptions:

1. The whole network traffic is IP traffic only

2. The live video content will be transmitted as “IP streaming video” with 1

Mbps data rate

3. The videoconferences will be understood as “video over IP” with a data

transmission rate of 256kbps inclusive of IP overhead.

4. The network interface to the other AVU equipment/services is the LAN

interface at each site between the VSAT station and the LC/CE/PA or

AVU-hub site.

Starting from the above assumptions, the AVU traffic and service requirements, descried in the preceding chapters, we will develop in a step-by-step procedure the most suitable AVU network solution. We will describe and analyse the network elements, provide at the end a cost comparison of different network designs and give a recommendation for a “best solution”.



Low Cost VSAT Technologies

The table below shows nearly all VSAT systems on the market today, which might be considered as a return channel system for the AVU network. Not included in the table are systems, not yet on the market (under development), as for instance several DVB-RCS systems and all DOCSIS systems, or VSAT systems with return channel rates lower than 200 kbps and also several specialized VSAT systems not available for free trading on the market, as e.g. military systems and proprietary systems of specialized service providers (e.g. Intelsat DAMA, Tachyon and others)



Overview VSAT systems

No Suplier Inbound Type

Product-name

inbound rate

Price* per hub

Price* per terminal

1 IPRICOT CDMA ? 2 Mbps 5.000 (with Transceiver)

2 Aloha Networks CRMA SkyDsl

3 ViaSat CRMA ArcLight 512 kbps

4 Gilat SCPC DAMA

DialAway 132 kbps

5 Radyne Comstream

SCPC IPsat 2 Mbps

6 ComtechEfData SCPC DAMA

MIDAS 5 Mbps

7 Shiron SCPC DAMA

InterSky 2 Mbps 380.000 (100 inroutes and DVB uplink system)

1.600 (additional inroute)

3.400 (384kbps inroute)

8 Gilat TDMA SkyStar 320 kbps

9 Hughes network systems

TDMA Direcway 512kbps 250.000 (with one inroute)

1.000

10 IDIRECT TDMA NetModem II

718 kbps 270.000 (NMS and three inroutes)

5.000



11 NDsatcom TDMA SkyWAN 2 Mbps Hubless system

Ca. 50.000 for NMS and 2 IDU

11.000

12 Radyne Comstream

TDMA IPsat+ 512k

13 STM TDMA Olante 192kbps

14 Viasat TDMA LinkStar 1.15 Mbps

150.000 (with 10 inroutes)

8.000 (additional inroute)

250.000 (DVB-S uplink system)

1.600

15 ViaSat TDMA LinkWay 2 Mbps Hubless system (ca. 50.000 for NMS)

10.000 (Link-way IP)

16 EMS TDMA (DVB-RCS)

OEM, Known as 9780 from Alcatel and SkyArcs from NDsatcom

2 Mbps 500.000 – 750.000

2.000 – 2.500

17 NDsatcom TDMA (DVB-RCS)

SkyARCS 2 Mbps 750.000 (incl. DVB uplink, but without ODU, with 4 inroutes)

50.000 for each 4 additional inroutes

1.600 (incl. 1.3W ODU, for small lots e.g. 50 pieces)

18 Newtec TDMA (DVB-RCS)

2 Mbps 500.000 – 800.000

2.000 – 2.500 (with ODU and POP)

* price in Euro for terminal indoor unit and hub return channel system only. Antenna, transmitter and hub uplink system at extra costs



The term “Low Cost VSAT System” is not without any ambiguity. Different VSAT systems were designed for different traffic flows and services. From the point of view of system costs different systems under different circumstances will deliver a cost optimum for different criteria.

Especially the DVB-RCS systems were designed for a very large number of terminals; up to 10.000 and more. Thus the hub costs are relatively high, but the terminal-IDU costs will drop over the next years down to 1.000 USD and lower.

VSAT systems like Gilat SkyStar and Hughes DirecWay were designed for terminals with relatively low average inroute traffic up to several kbps per terminal. In principle these systems could carry inroute traffic of more than 100 kbps per terminal, but in that case the hub costs will rise up dramatically. Additionally these systems have very low bandwidth efficiency on the inroute, which causes significantly higher space segment costs per transmitted bit compared with other systems.

Thus the approach of this study is to find on the basic of the analysis of the AVU traffic requirements the “optimum” VSAT system solution for the AVU network. As the main optimisation criterion the overall system costs should be minimized. In parallel the remote terminal costs should also be minimized to keep the “Entry level” for the LC’s as low as possible.

5.3.2 Baselines for the Network Design

As shown by the table “Total AVU traffic requirements per network” (see chapter “Revised AVU Traffic Requirements”) 98% of the whole network traffic is dedicated to a hub<>terminal star subnetwork. The Outbound/Inbound traffic ratio is about 4:1. For this traffic type the “classical” scheme could be used: large hub antenna and relatively small terminal antennas. The advantage of such a scheme is the fact, that the remote terminals require relatively low powered transmitters to transmit to the hub. This decreases the terminal price and the inroute space segment costs significantly.

The inter terminal traffic (meshed traffic) is only required by the video conferencing services between the CE’s and the PA’s and by the live video feeds from the CE’s to all other CE’s/LC’s.

The live video feeds from the CE’s are transmitted only from one of the CE’s at a time. In this case the CE should be equipped with the appropriate transmission



capacity (transmitter power), which could increase the costs of the CE terminals significantly.

As the provided service is video broadcast, the time delay within the transmission path CE>terminal is not really significant. The CE could send the live video feed to the hub station, and the hub station could then broadcast the live feed within the hub outbound carrier(s).

The video conferencing service has to be provided to two different and not associated user groups: all CE’s in one group and all PA’s in the other group.

Videoconferencing as a real time service is very sensitive to the time delay on the transmission path. The QoS (Quality of service) drops significantly if the delay exceeds 150ms per direction. In case of satellite transmission the delay due to the transmission path length of more than 70.000 km in one direction is already at least 0,25 seconds. In case of a double hop: CE > Hub > CE the delay increases to 0,5 seconds. Such delay would require a very high discipline from the participants, which usually is unacceptable.

As a basis it will be assumed that all traffic within the network is IP traffic only.



5.3.3 Generic network design

The generic network consists of a hub system, providing all AVU local services and the interconnection to the Internet Backbone. The hub transmits an outbound carrier as a broadcast carrier. This outbound carrier will be received by all terminals (LC, CE, PA) within the AVU network. An Inbound carrier system provides to the terminals the capability to transmit data to the hub and further to the Internet or to the hub servers.

The single-hop videoconference subnetworks are implemented as additional network structures on its own satellite carrier system.



5.3.4 Outbound System

As shown by the table “Total AVU traffic Requirements per Network” (see above) 80% of the total network traffic is directed from the hub to the remote terminals. This traffic is mostly Internet downlink traffic and partially (5%) video broadcast traffic.

As assumed in the “baselines” all traffic within the network is IP traffic. As IP is a connectionless protocol and each satellite carrier is a broadcast carrier within the related transponder coverage the IP packets could be send directly as a usual SCPC simplex carrier, received by all terminals of the AVU network.

In this case no special equipment at the hub site is needed.

Unfortunately this approach requires expensive SCPC demodulators and also high performance routers at each terminal station. As the AVU network consists of 150 stations, this would significantly increase the terminal costs in comparison to a DVB-S solution.

For IP data broadcasting and multicasting the well-proven and introduced DVB technology is widely used und became more and more the technology of choice for such kind off applications. The DVB technology, originally designed for transmission of streaming digital media, was adapted during the last years to IP data transmission.

A DVB stream consists of an endless chain of 188 Byte MPEG-2 packages. The first 4 bytes of each package contain system information; the remaining 184 bytes are used for content data transportation. Each package is labelled with a so-called PID (Program Identifier), assigning each MPEG package to a defined content stream.

The DVB-Decoders receives the aggregated DVB stream. Each DVB decoder contains a PID table with those PIDs, related to the given DVB decoder. The DVB decoder filters the incoming MPEG-packet stream and directs only those packets to the user, which belongs to him.

In case of IP traffic the DVB decoder also fulfils demultiplexer function, composing the original IP packets in case they are spread about two or more MPEG packets.

As the DVB decoders are mass products, the decoders by itself are relatively low priced devices (ca. 100 USD). Due to the fact, that the very processing power



intense traffic filtering function is provided by the DVB decoders, the local IP routers at each AVU site could be in that case usual medium and low power office routers.



5.3.5 Inbound System

The Inbound system has to carry traffic of 200 kbps for each LC, up to 1.2 Mbps for a CE and 30kbps for each PA terminal. This traffic requirement is a raw estimation. Unfortunately there is not any experience or statistical data about the real return channel traffic of the AVU network.

The inbound system has the most influence on the costs of the remote terminals.

If one assumes terminal costs in the range of 10.000…15.000 $US the overall terminal costs of the AVU network will be ca. 2 Mio $US. This is much more than the estimated hub CAPEX. Thus the terminal costs have a major influence on the overall AVU network CAPEX and the inbound system should be chosen very carefully.

The AVU inbound system could be designed as:

1. SCPC fixed rate inbound channel to each terminal

2. SCPC flexible rate inbound channel to each terminal (so called BoD

system)

3. Shared inbound channels (a group of terminals shares one inbound

channel)

SCPC fixed rate systems requires at each terminal an SCPC-modulator and at the hub site a SCPC demodulator for each site.



SCPC return channel system

Forward Link

IP over DVB

Return Link

Internet Backbone

Learning Center

Learning Center

NCC Nairobi

LAN

LAN

LAN



Returnlink LC to Hub: SCPC fixed rate, fixed frequency

Learning Center

DVB-Modulator

DemodDemodEach Demod Assigned toOne remote terminal

LAN

Server

IP-DVB-Encapsulator

Forward Link

IP over DVB

Return Link

Internet Backbone

Learning Center

Learning Center

NCC Nairobi

LAN

LAN

LAN



Returnlink LC to Hub: SCPC fixed rate, fixed frequency

Learning Center

DVB-Modulator


LAN

Server

IP-DVB-Encapsulator



The advantages of this solution are:

- The possibility to use a broad spectrum of modulation and error correction

methods, implemented in a wide range of products on the market.

- The link is fully transparent to the transmitted data

- No additional system overhead

The disadvantages are:

- it is not possible to change dynamically data rate and/or frequency of the

carrier

- standard SCPC Modem systems are relatively expansive

The fixed rate SCPC solution is a good approach in case the inbound traffic from each station is relatively stable or in other words, the average required inbound bandwidth is close to the maximum needed inbound bandwidth. In that case it makes no or only little sense to optimise bandwidth usage by sharing the inbound capacity within groups or all remote terminals.

In case of the AVU network we have no exact data or at least imagination about the real inbound traffic – not by average and not by statistical variation.

SCPC flexible rate inbound systems are provided by a few of vendors only as specialized DAMA-like systems.

The inbound from each terminal is a usual SCPC carrier, but the data rate and frequency of that carrier could be changed dynamically within seconds according to the requested inbound capacity.



SCPC DAMA (Bandwidth on Demand) return channel system

Forward Link

IP over DVB

Return Link

Internet Backbone

Learning Center

Learning Center

NCC Nairobi

LAN

LAN

LAN



Returnlink LC to Hub: SCPC variable rate, variable frequency

Learning Center

DVB-Modulator


LAN

Server VoIPGateway

IP-DVB-Encapsulator

Carrier Management

Subsystem

Controls theLocal demodsAnd theRemoteModulators

Forward Link

IP over DVB

Return Link

Internet Backbone

Learning Center

Learning Center

NCC Nairobi

LAN

LAN

LAN



Returnlink LC to Hub: SCPC variable rate, variable frequency

Learning Center

DVB-Modulator


LAN

Server VoIPGateway

IP-DVB-Encapsulator

Carrier Management

Subsystem

Controls theLocal demodsAnd theRemoteModulators



The main advantage of such a system is the possibility to re-assign the bandwidth of a given bandwidth pool to different inbound channels as needed.

This approach makes the inbound system very scalable: at the beginning of the network rollout it is possible to start with a relatively low inbound bandwidth pool. If during the network expansion the average inbound bandwidth requirement of the system exceeds the existing bandwidth pool, additional space segment could be purchased and assigned to the bandwidth pool.

The main disadvantage of such systems is the fact, that all systems available on the market do not support sophisticated modulation and error correction methods. As in those hub based return channel systems usually the hub antenna is relatively big and thus the inbound channels are usually satellite bandwidth limited and not satellite power limited, in the most cases sophisticated inbound channel modulation technologies do not bring really a big effect in terms of bandwidth efficiency.

Shared inbound channel systems are implemented by several vendors with several technologies.



Shared Inbound return channel system

Forward Link

IP over DVB

Return Link

Internet Backbone

Learning Center

Learning Center

NCC Nairobi

LAN

LAN

LAN



Returnlink LC to Hub: several terminals using the same inroute carrier

Learning Center

DVB-ModulatorInrouteSubsystem

One inrouteSubsystem To each Inroute carrier

LAN

RCS-NMS

IP-DVB-Encapsulator

InrouteSubsystem

NMS andTMSSystem

Forward Link

IP over DVB

Return Link

Internet Backbone

Learning Center

Learning Center

NCC Nairobi

LAN

LAN

LAN



Returnlink LC to Hub: several terminals using the same inroute carrier

Learning Center

DVB-ModulatorInrouteSubsystem

One inrouteSubsystem To each Inroute carrier

LAN

RCS-NMS

IP-DVB-Encapsulator

InrouteSubsystem

NMS andTMSSystem



Most of these systems are designed as access systems for terminals with very pronounced burst-like traffic but with relatively low average traffic, e.g. of some kbps during the day or even the “Busy Hour”. In that case the inbound channel acts as a traffic concentrator, so that the inbound channel capacity should only be slightly higher than the total of the average transmission requirements of all connected terminals. This results in a very high bandwidth saving in the inbound system in relation to a SCPC fixed rate inbound system.

Most of these systems available on the market use some kind of TDMA technology. However, TDMA techniques require high system overhead (up to 30% on the inbound).

In addition any terminal must be able to transmit at the full inbound data rate, regardless of the required peak data rate of the given terminal. Not to drive the cost of the terminals by the costs for high power transmitter amplifiers, the bandwidth of the inbounds should be as low as possible.

In case of the AVU network the inbound requirement for the LC is 200 kbps. As the LC LAN already acts as traffic concentrator for the attached Internet PC’s any further concentration can be excluded. Even under the assumption that the average required inbound datarate of a LC could be as low as 50 kbps, most of the inbound systems on the market could not bew used in an efficient manner for the AVU network as will be shown below:

Well known and established systems like the Gilat SkyStar, the Hughes Directway or the ViaSat LinkWay support inbound carriers of up to 350 kbps. Taking in account the system overhead the theoretically usable inbound transmissionrate of those systems is 300 kbps maximum. (Note: as these systems are using slotted aloha it is not recommended to use more than 40% of the inbound capacity, otherwise the collision rate on the inbound increases rapidly and the usable transmissionrate will drop instead of increase). This means, that no more than 6 LC’s could be assigned to one inbound system and consequently the cost of one hub inbound subsystem would have to be shared among only 6 terminals.

Such “low bandwidth” inbound systems could be a good solution for the PA (Houses of Parliaments) network. However, it would not be feasible from an economic point of view to introduce such a system for only some 50 VSAT sites.

Six terminals is a too low number to reach a significant multiplexing effect. At least 20..30 terminals per inbound should share a common inbound carrier. This



would be possible with inbound carriers of 2 Mbps or even higher. Such inbound capacity could be provided by systems like IDIRECT NetModem, NDsatcom SkyWAN, ViaSat Linkway and also by the new DVB-RCS-systems.

Unfortunately, indoor terminals of these systems are much more expensive than those of the systems mentioned above.

In addition the following drawback has to be taken into consideration: to transmit a 2Mbps carrier the VSAT´s would have to be equipped with much higher transmitting power, which would increase the overall costs of the terminals significantly. To keep the overall terminal costs low, the inbound carrier transmissionrate should be selected very carefully and should not be oversized.

5.3.6 Video Conference Network

Within the PA subnetwork additional four 256kbps SCPC simplex carriers will be implemented. Each PA site will be equipped with a modulator capable of transmitting on any of four predefined frequencies and will also be equipped with four demodulators receiving any of the four frequencies. A videoconference will be established by the hub operator on demand. The hub operator can control with a special management PC the videoconference modulators and demodulators of each terminal and assign on demand one out of the four SCPC carriers to one out of four active videoconference sites.

The outdoor units of all PA terminals have to be designed in such a way, that the videoconference carriers could be transmitted directly to all other participating (PA-) terminals. This requires relatively powerful transmitters at each PA terminal, but assures single hop videoconferences.

As videoconference system any IP-based system can be used (e.g. from Polycom and Picturetel) or any PC-based systems can be used (e.g. Netmeeting).

The hub operator workstation should be equipped with specially designed management software, e.g. based on an easy to handle touch screen interface.

detecon technical final report part1-1

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