8th SADC SUPERVISORY BOARD MEETING Cape Town, South Africa WP-1.1 (Agenda Item... · 2012. 3....

Date: 22 - 23 March 2011

WP1.1 : Agenda Item 7.1 : Report

of AFI VSAT Managers Meeting

8th SADC SUPERVISORY BOARD MEETING

Cape Town, South Africa

Summary of Presentation

This presentation covers the following tasks conducted by the

Technical Group of the AFI Aeronautical VSAT Managers Meeting:

• Summary of the GAP analysis conducted

• Design philosophy and revision of the ATN connectivity diagramme

• Utilization of existing infrastructure

• Technical solutions considered

• Spectrum requirements

• Costing of various solutions

• Spares options

• Projected Life-cycle costing

• Recommendations

• Proposed technical solution for the AFI Region

Summary of GAP Analysis/1

• In accordance with the Best Practices established at the AFI

VSAT/1 meeting, an in depth GAP analysis was conducted by the

Technical Team

• A copy of the complete GAP analysis will be published on the ESAF

ICAO website and the following is a brief summary of the most

important GAPs found:

− Basically two access satellite methods are utilized in the four

relevant VSAT networks i.e. FDMA and TDMA. Operation on a

single access method is essential to ensure seamless operation

− Three out of the four networks operate on the same satellite – it

is therefore important to establish operation on the fourth

network on the same satellite, or to establish an alternative

solution to ensure cost effective interconnectivity

− An NCC is not available for all networks and efficient

management is lacking in some of the networks and must be

addressed effectively in a new solution.

Summary of GAP Analysis/1

− Maintenance philosophies, fault reporting procedures and

management of spares differs significantly – this must still be

addressed by the Technical Team

− All services are dependent on a single satellite and a cost

effective solution must be investigated together with

discussions with Intelsat to ensure continuity of services in

case of disruption or failure of IS10-02

− Availability of sufficient spectrum could become a problem in

future that will have to be addressed effectively by the VSAT

Managers in cooperation with Intelsat

• The deficiencies as listed above and others must be address in the

technical solution proposed by the Technical Group.

Original ATN BB Connectivity

as proposed by ATN Task Force

ATN Task Force

Regional Connectivity

Design Philosophy: From original to

New AFI ATN Network Design/1

• The objectives established by the First AFI Aeronautical VSAT

Managers meeting (AFI VSAT/1) in Durban, KwaZulu-Natal as

applicable to the Technical Group are listed below:

− Develop a sustainable and integrated/interoperable VSAT

network to provide aviation communications services in the AFI

Region.

− Upgrade the technical capabilities of the networks to comply

with the global best practice, user requirements and ICAO’s

requirement

− Achieve the ATN concept for AFI

− Apply appropriate cost-effective technologies.



Together with the objectives of the AFI VSAT/1 the inter-regional

connectivity of the original ATN BB Router connectivity design by the

ATN Task Force was studied and the following criteria were applied to

identify the shortcomings:

• Any two regions must be connected by at least two circuits; and

• The two circuits must be independent

The following changes were therefore proposed:

• The interconnection between AFISNET and NAFISAT contained

effectively only one circuit i.e. N'Djamena /Khartoum. It was

therefore necessary to add the Brazzaville/Nairobi circuit.



• Similarly there was also only one connection between SADC2 and

CAFSAT. A node was therefore added at Luanda as well as a

circuit between Luanda and Recife. It must also be noted that

Luanda is part of CAFSAT although the site has not yet been

implemented.

• In the case of SADC and NAFISAT there were two connections,

however both are connected to Nairobi and the two connections

are therefore not independent. It was therefore proposed to add

another circuit between Khartoum and Kinshasa to resolve this.

• The same argument also apply to SADC/AFISNET, albeit to a

lessor extend and a Brazzaville/Luanda circuit is therefore

included.



• A similar problem exists between CAFSAT and AFISNET where

there are not two independent circuits. It is however difficult to

resolve this in a cost effective manner and will have to be

addressed at a later stage.

• The following additional circuits were also added:

− Jeddah/Khartoum and Jeddah/Addis Ababa to address

connectivity with the Middle East region.

− Conakry/ Dakar and Conakry/Niamey

− Accra/Dakar and Accra/Niamey

− Kano/Niamey and Kano/N'Djamena

• These circuits were added basically because the nodes are not

operated and maintained by ASECNA although they are part of

AFISNET.



• The circuit Dakar/Alger was removed (to reduce the number of

circuits operating from/to Dakar (8 in total) and to get a more

balanced distribution)

Considering the above rational, the following Regional connectivity

was developed.

New Revised Regional AFI ATN

Connectivity

Revised AFI ATN Network/1

Using the new revised connectivity of the ATN a new connectivity

diagram was developed. The proposed solution of the Technical

Group is based on the following fundamental assumptions:

• All four networks i.e. AFISNET, SADC2, NAFISAT and CAFSAT

have made substantial investment in their existing infrastructure,

which have not yet reached the end of operational life

• Three of the networks operate on the same satellite i.e. IS 10-02.

The exception is CAFSAT, however connectivity can be establish

between this network and the AFI Region by obtaining spectrum on

the Global beam of IS 10-02

• It will be endeavored to establish a single satellite access method

for the proposed technical solution to provide the most cost

effective solution, while taking into account operational and

financial aspects


• Existing infrastructure will be utilized where possible to reduce the

cost of implementing the AFI ATN network.

• Although the new solution will mainly support IP based

applications, provision must still be made for services based on

legacy protocols for the foreseeable future.

• The overlay network must be secure and not dependent on

terrestrial services located outside the security areas of the

ANSP's, in other words where the ANSP does not have any control

over its availability, management, etc.


It was envisaged by the Technical Team that by implementing the

revised ATN connectivity requirements as an “overlay” on top of the

existing networks the above fundamental assumption will be

complied with i.e.

• The investment in all four networks will be retained in the

short/medium term. The services from the lower networks can be

transferred to the upper layer as and when required

• It is the intention to operate all four networks on the same

satellite thereby ensuring interoperability

• Establishing the same satellite access method will ensure

seamless operation


• The implementation of the ATN overlay will be cost-effective as

existing infrastructure will be utilized

• The bottom layers (existing networks) will continue to support

applications based on legacy protocols, while the new upper

(overlay) network will support all IP based applications

• ANSP will have full control over the ATN Network availability,

management, etc.

The result is shown in the following slide and is the revised ATN

Overlay that will be proposed to APIRG/18 for approval:

ATN Overlay Connectivity as

Proposed by Technical Group/1

ATN Overlay Connectivity as

Proposed by Technical Group/2AFI ATN OVERLAY

CAFSAT

AFISNET

NAFISAT

SADC/2

IP6

IP4

IP6

IP4

IP6

IP4

IP6

IP4

IP6

IP4

IP6

IP4IP6

IP4

IP6

IP4IP6

IP4

IP6

IP4IP6

IP4

IP6

IP4

Utilising Existing Infrastructure/1

Active

Co

mb

ine

r

RFT

Radio

Frequency

Transmitter

Active

Sp

litte

r

LNB

IDU5000

Indoor Unit

FRAD

Frame Relay

Access device

User

application:

ATS/DS

User

application:

AFTN

New Equipment

Option A : TDMA - IDU7000 1+0 IDU

(Typical NAFISAT/SADC2 VSAT Terminal)

RFT

Radio

Frequency

Transmitter

LNB

Sw

itch

Existing Equipment

CPE

AMHS

AIDC

CAD

TBD...

IP

Mo

de

m

RO

UT

ER

IDU7000

Utilising Existing Infrastructure/2

Co

mb

ine

rS

plit

ter

Modem

FADFrame Relay

Access

device

User

application:

ATS/DS

User

application:

AFTN

Option C - FDMA Comtech: 1 + 0 IDU

(Typical AFISNET VSAT Terminal)

TWT/SSPA

LNB

TWT/SSPA

LNBCPE

AMHS

AIDC

CAD

TBD...

New Equipment

Existing Equipment

Number of modems

depends on number

of circuits

Modem

Contech CDM570L

Modem

Contech CDM570L

Technical Solutions Considered

The following solutions were considered:

• A TDMA solution using NDSatcom Skywan IDU 7000 equipment

• An FDMA solution using Datum PSM500 modems, SDM9220

FRAD equipment and Cisco router equipment

• An FDMA solution using Comtech modems and Cisco router

equipment

The following configurations for each of the above options were

costed:

• Indoor equipment in 1 + 0 configuration (i.e. Main equipment only)

• Indoor equipment in 1 + 1 configuration (i.e. Main and Standby

equipment)

Spares Options Considered

The following spares options were considered and costed for

comparison purposes:

• Option 1: Provision of one set of spare equipment for each of the

4 regions. This is typical of what will be required if each region has

its own centralised maintenance centre.

• Option 2: Provision of one set of spares for each VSAT node.

This is typically of what will be required for decentralised

maintenance for 25 nodes.

• Option 3: A hybrid maintenance setup which is a combination of

the above options. In this case AFISNET & CAFSAT will have

decentralised- and SADC & NAFISAT centralised maintenance

Spectrum Requirements

• A network sizing was completed for both network access

techniques and the required carrier traffic and satellite bandwidth

calculated for both FDMA and TDMA.

• The carrier sizes as calculated and its associated parameters were

entered into the INTELSAT Transmission software program (LST)

to calculate the required occupied bandwidth.

• The occupied satellite bandwidth for both the FDMA and TDMA is

given in the table below:

− FDMA - 4.4620 MHz

− TDMA - 4.4828 MHz

• The calculations are based on certain assumptions for comparison

purposes and the final values may be different

Cost Comparisons of VSAT Solutions

NAFISAT Region SADC Region AFISNET Region CAFSAT RegionTotal Cost for AFI ATN

Network

435,623.78$ 569,582.30$ 859,220.50$ 670,638.85$ 2,535,065.43$

17.2% 22.5% 33.9% 26.5%

647,318.76$ 825,295.67$ 1,233,755.10$ 847,466.41$ 3,553,835.94$

18.2% 23.2% 34.7% 23.8%

587,432.36$ 749,136.43$ 1,133,398.20$ 802,618.95$ 3,272,585.94$

18.0% 22.9% 34.6% 24.5%

593,215.91$ 662,071.82$ 1,016,313.03$ 767,026.50$ 3,038,627.26$

19.5% 21.8% 33.4% 25.2%

995,816.44$ 1,266,047.46$ 1,782,694.96$ 1,125,783.44$ 5,170,342.30$

19.3% 24.5% 34.5% 21.8%

814,269.38$ 1,035,956.97$ 1,483,426.64$ 992,031.38$ 4,325,684.37$

18.8% 23.9% 34.3% 22.9%

Option E (FDMA)

Datum PSM500 Modem & SDM9220

Option F (FDMA)

Comtech CDM570L

Cost Comparison of VSAT Solutions for an AFI ATN Network (including Option 3 Spares)

Region -->

Option A (TDMA)

IDU7000

Option B (FDMA)

Datum PSM500 Modem & SDM9220

Option C (FDMA)

Comtech CDM 570 L

IDU

in 1

+ 1

Co

nfi

gura

tio

nID

U in

1 +

0 C

on

figu

rati

on

Percentage of Total cost




Option D (TDMA)

IDU7000



The costs are for comparison purposes and may differ for the

final solution

Life-Cycle Cost Comparison:

1 + 0 Configuration

Option A (TDMA: 1 + 0) USD Interest Rate = 9%

Capex (including Spares Option 3) 2,535,065.00 Period (years) = 6

Operational cost/month:

a) Spectrum Cost 15,689.80

b) Maintenance TBD

Life-cycle cost Year 1 Year 2 Year 3 Year 4 Year 5 Year 6 Total for 5 Years

Cost of capital (9%, 6 years) 565,116.14 565,116.14 565,116.14 565,116.14 565,116.14 565,116.14 3,390,696.84

Operational cost 188,277.60 188,277.60 188,277.60 188,277.60 188,277.60 188277.6 941,388.00

Grand Total 4,332,084.84 Option C (FDMA Comtech: 1 + 0) USD

Capex (including Spares Option 3) 3,272,586.00



b) Maintenance TBD



Operational cost 187,404.00 187,404.00 187,404.00 187,404.00 187,404.00 187404 937,020.00

Grand Total 5,314,164.97

Life-Cycle Cost Comparison:

1 + 1 ConfigurationOption D (TDMA: 1 + 1) USD




b) Maintenance TBD



Operational cost 188,277.60 188,277.60 188,277.60 188,277.60 188,277.60 188277.6 941,388.00

Grand Total 5,005,608.43 Option F (FDMA: Comtech 1 + 1) USD




b) Maintenance TBD



Operational cost 187,404.00 187,404.00 187,404.00 187,404.00 187,404.00 187404 937,020.00

Grand Total 6,722,703.24

Recommendations

Considering the calculated cost options, it was recommended that

the Option D, i.e. the TDMA solution (satellite access method) be

accepted as the preferred technical solution. This decision is

proposed for the following reasons:

• Of the options considered both TDMA solutions are lower in cost than the FDMA

solutions in 1+0 and 1+1 configurations.

Subsequently one has to consider which of the TDMA

configurations to recommend:

• Although Option D (TDMA 1+0) has a lower Life-Cycle cost than Option F (TDMA

1+1), the proposed ATN solution will form the backbone network structure for the

AFI Region and availability must be maximised This can be done by using the

TDMA 1+1 solution.

• It must also be noted that Option F also includes the spares Option 3 i.e. a hybrid

maintenance setup. This is the maintenance philosophies presently supported by

the AFISNET/CAFSAT and SADC/NAFISAT Regions.

• If the 1 + 0 is recommended the maintenance philosophies have to be

reconsidered thus reducing the cost advantage of the 1+0 over 1+1 solution.

• The 1 + 1 configuration was therefore recommended by the Technical Group

Final Proposed Solution/1

Act

ive

Co

mb

ine

rA

ctiv

e S

plit

ter

IDU5000

Indoor Unit

FRAD

Frame Relay

Access device

User

application:

ATS/DS

User

application:

AFTN

Option D-1 : TDMA - IDU7000 1 + 1 IDU

(Typical NAFISAT/SADC2 VSAT Terminal)

RFT

Radio

Frequency

Transmitter

LNB

RFT

Radio

Frequency

Transmitter

LNB

Sw

itch

CPE

AMHS

AIDC

CAD

TBD...

IP

Mo

de

m

RO

UT

ER

IDU7000M

od

em

RO

UT

ER

IDU7000 New Equipment

Existing Equipment

Final Proposed Solution/1

Co

mb

ine

rS

plit

ter

Modem

FADFrame Relay

Access

device

User

application:

ATS/DS

User

application:

AFTN

Option D-2: FDMA + TDMA Overlay: IDU7000 1+1 IDU

(Typical AFISNET VSAT Terminal)

TWT/SSPA

LNB

TWT/SSPA

LNB

Sw

itch

CPE

AMHS

AIDC

CAD

TBD...

IPM

od

em

RO

UT

ER

IDU7000M

od

em

RO

UT

ER

IDU7000

New Equipment

Existing Equipment

Number of modems

depends on number

of circuits

User

application:

VHF

Thank You

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