vsat

VSAT

Subject : SAK 5306Advanced Computer Network

Project 1

Satellite CommunicationVERY SMALL APERTURE TERMINAL (VSAT)

Prepared for : En. Fahrul Hakim AyobPrepared by : Amaruddin Isa GS12350

Zulkeflee Kusin GS12317Siti Istianah Mahdzur GS12287

VSAT

Date : 22nd July 2003

Program Master of Science (Computer Science)Faculty of Science Computer and Information TechnologyUniversiti Putra Malaysia43400 Serdang Selangor

CONTENTS

1.0. INTRODUCTION 1

2.0. OVERVIEW OF SATELLITE COMMUNICATION 12.1. Satellite Communication 12.2 Type of Satellite Service 1

3.0. VSAT (VERY SMALL APERTURE TERMINAL) 23.1. Specification 33.2. VSAT Service 53.3. VSAT Topology 53.4. How VSAT Work 73.5. Multiple Accessing Schemes 7

4.0. VSAT NETWORK CHARACTERICTICS 12

5.0 IMPLEMENTATION OF VSAT TECHNOLOGY IN MALAYSIA 145.1. E-BARIO Synthesis 14 5.2. Opportunities in VSAT Technology 17

6.0. TELEKOM MALAYSIA VSAT – TM VSAT 186.1. TM VSAT 186.2. TM VSAT Architecture 196.3. TM VSAT Reachability 20

7.0. MAXIS VSAT 217.1. Type of Maxis VSAT Services 217.2. Benefit of MAXIS VSAT Services 23

8.0 EVOLUTION OF MALAYSIA MEASAT 258.1. MEASAT 258.2. Ground Segment 25

9.0 CONCLUSION 27

VSAT

References 28

Appendices

i. Telekom Malaysia VSAT Services rate 29

ii. Measat-1, C Band Coverage 30

iii. High Speed VSAT 31

iv. Evolution of VSAT System 32

v. Broadband Access via Satellite 33

1.0. INTRODUCTION

Satellite Communication using VSAT (Very Small Aperture Terminal) since the science fiction on radio transmission through space using geo-synchronous earth satellite, provider has progressed significantly in the field of satellite communications. The early earth stations were large and expensive. The reason for the size and complexity of the early stations was not related to inadequate performance. In fact, the antennas had very high efficiency and the noise temperatures of their receivers were low. However, the satellites at that time had a relatively poor performance providing considerably low RF (radio frequency) power per transponder and a rather high noise temperature for the on-board receivers. Additionally, satellites were then considered suitable only for very long distance communication. Gradually, satellite communications have appeared as regional systems requiring smaller coverage on the earth’s surface enabling higher gain antennas. Subsequently, increase in transponder out-put power, introduction of systems having several spot beams, development of field-effect transistor amplifier for low noise receivers as well as its availability as power amplifier have changed the satellite communication scenario. Once it was possible to envisage an all solid-state transmit and receive earth station even with a rather low power output, low price, large quantity, VSAT-based earth station design could be conceived.

2.0. OVERVIEW OF SATELLITE COMMUNICATION

2.1. Satellite Communication

Satellite Communication is a technology of data transmission whether one-way data broadcasting or two-way interactive using radio frequency as a medium.

It consists of:i. Space Segment or Satellite ( eg. Measat, Intelsat and Inmarsat)

VSAT

ii. Ground Segment or earth station which includes Antenna, Outdoor Unit, Inter Facility Link, Indoor Unit and Customer Premises Equipment.

2.2. Type of Satellite Service

Satellite communication provides services;

i. International Telephony – using Public Switched Telephone Network (PSTN)– Intermediate Data Rate (IDR)– Time Division Multiple Access (TDMA)

ii. Broadcasting– TV Uplink– Television Receive Only (TVRO)– Digital Satellite News Gathering (DSNG)

iii. VSAT- Very Small Aperture Terminal– Personal Earth Station (PES-TDMA)– Telephony Earth Station (TES-TDMA)– Domestic IDR/Single Channel Per Carrier (SCPC)– VSAT Dialaway– VSAT SkyStar Advantage– VSAT Faraway

Note :HPA – High Power Amplifier, LNA- Low Noise Amplifier (Earth station equipment that amplifies the transmit RF signal. ) CPE – customer premises equipment ( eg. Telephone, PABX, Ethernet hub, host server, etc)

Satellite Communication Concept

Transmitting Earth Station

Receiving Earth Station

Uplink 6 GHz

Downlink 4 GHz

HPA

Up Converter

Satellite ModemCPE

PSTN

LNA

Down ConverterSatellite ModemCPE

PSTN

C Band – 6/4GHzKu Band -14/12GHzKa Band – 30/20GHz

VSAT

3.0. VSAT (VERY SMALL APERTURE TERMINAL)

VSAT( Very Small Aperture Terminal) is a satellite-based communications service that offers businesses and government agencies flexible and reliable communications solutions, both nationally and internationally, on land and at sea.

VSAT networks provide:

i. Rapid, reliable satellite transmission of data, voice and video and an ability to allocate resources (bandwidth and amplification power) to different users over the coverage region as needed.

ii. VSAT industry is offering fixed network solutions that can provide a full suite of services at reasonable price. eg: a toll quality voice channel via VSAT is available between 3-15 cents/minute today.

iii. Easy to provide point-to-multipoint (broadcast), multipoint-to-point (data collection), point-to-point communications and broadband multimedia services.

iv. VSATs are serviced not only in cases where the land areas are difficult to install, say in the case of remote locations, water areas, and large volumes of air space.

v. An ability to have direct access to users and user premises.

3.1. Specification

VSAT is a term widely used in the satellite industry to describe an earth station that is installed on the ground to receive communications from a satellite or to communicate with other ground stations by transmitting to and receiving from satellite spacecraft. The ground station may be used only for reception, but is typically capable of both receiving and transmitting. Major components of a VSAT are generally grouped in two categories, ODU (outdoor unit) and IDU (indoor unit).

3.1.1. Out Door Unit The ODU, so named because the components reside outdoors, includes; the antenna (typically ranging in size from 3.8 meters down to as small as 0.6m in diameter), equipped with a feed system capable of receiving and transmitting, a microwave radio, also known as a HPA High Power Amplifier, and an LNA (low noise amplifier) used to convert the signal gathered by the feed.

VSAT

Frequency Bands are available for use in C, Ku, or Ka frequency bands and are sold by wattage capability. A complicated calculation called a "Link Budget" is performed by the satellite operator to determine both the size of the antenna and how much power (wattage) will be required to complete the transmission link between the ground station and the satellite. Frequency Bands are sometimes combined with the LNA's which are used as part of the receiving operation. The resulting combination is called a "transceiver" and saves some integration time during the installation process.

3.1.2. IDU Indoor Unit The indoor unit is typically composed of a single unit called a modem. A satellite modem is different than a telephone modem, and is used to convert the data, video, or voice generated by the customer application for transmission over satellite. The modem takes the signals from your computer, phone or other device and changes them so they can be sent to the ODU which transmits them out to the satellite and eventually to other ground stations.

Antenna diameter : 0.6m – 3.8m Traffic Capacity : 9.6kbps – 2MbpsFrequency Bands : C-band (4-6Ghz) or

Ku-Band (12-14Ghz)Ka-Band (30/20Ghz)

Use of satellite : Geo-stationary satellite (36,000km above equator)

Network : Point-to-pointConfiguration: Point-to-multipoint

Equipment List : – Antenna;– Outdoor Unit (High Power Amplifier (HPA), Low Noise Amplifier (LNA),

Solid-State Power Amplifier (SSPA))– Indoor Unit (chassis)

Note: - Antenna size is used to describe the ability of the antenna to amplify the signal strength; - Outdoor unit (ODU) is connected through a low-loss coaxial cable to the indoor unit (IDU) called IFL (Inter facility Link).

VSAT

VSAT Configuration

3.2. VSAT Services

i. Interactive real time application:- Point of Sale/retail/Banking (eg. ATM)- Corporate data

ii. Telephony- Rural: individual subscribers- Corporate Telephony

iii. Intranet, Internet and IP infrastructure- Multimedia delivery (eg. video streaming)- Interactive distance learning/ training

iv. Direct-to-home- Broadband Internet access for consumers and businesses

3.3. VSAT Topology

3.3.1. Star

The hub station controls and monitors can communicate with a large number of dispersed VSATs. Generally, the Data Terminal Equipment and 3 hub antenna is in the range of 6-11m in diameter. Since all VSATs communicate with the central hub station only, this network is more suitable for centralized data applications.

VSAT

3.3.2. Mesh

A group of VSATs communicate directly with any other VSAT in the network without going through a central hub. A hub station in a mesh network performs only the monitoring and control functions. These networks are more suitable for telephony applications. 3.3.3 Hybrid Network

In practice usually using hybrid networks, where a part of the network operates on a star topology while some sites operate on a mesh topology, thereby accruing benefits of both topologies.

Star Topology by Maxis

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Mesh Topology by Maxis

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3.4 How VSAT Work

i. The size of a VSAT antenna varies. The feed-horn directs the transmitted power towards the antenna dish or collects the received power from it.

ii. It consists of an array of microwave passive components. Antenna size is used to describe the ability of the antenna to amplify the signal strength.

iii. The Radio Frequency Terminal (RFT) is mounted on the antenna frame and interconnected to the feed-horn (outdoor electronics) includes Low Noise Amplifiers (LNA) and down-converters for amplification and down conversion of the received signal respectively.

iv. LNAs are designed to minimize the noise added to the signal during this first stage of the converter as the noise performance of this stage determines the overall noise performance of the converter unit. The noise temperature is the parameter used to describe the performance of an LNA.

v. Up- converters and High Powered Amplifiers (HPA) are also part of the RFT and are used for up converting and amplifying the signal before transmitting to the feed-horn. The Up/Down converters convert frequencies between intermediate frequency (IF level 70 MHz) and radio frequency.

vi. Extended C band, the down converter receives the signal at 4.500 to 4.800 GHz and the up converter converts it to 6.725 to 7.025 GHz. The HPA ratings for VSATs range between 1 to 40 watts.

vii. The outdoor unit (ODU) is connected through a low-loss coaxial cable to the indoor unit (IDU). The typical limit of an (Interfacility Link) IFL cable is about 300 feet. The IDU consists of modulators that superimpose the user traffic signal on a carrier signal. This is then sent to the RFT for up conversion, amplification and transmission.

3.5. Multiple Accessing Schemes

The primary objective of the VSAT networks is to maximize the use of common satellite and other resources amongst all VSAT sites. The methods by which these networks optimize the use of satellite capacity, and spectrum utilization in a flexible and cost-effective manner are referred to as satellite access schemes. Each of the above topologies is associated with an appropriate satellite access scheme. Good network efficiency depends very much on the multiple accessing schemes. There are many

VSAT

different access techniques tailored to match customer applications. Access techniques including stream, transaction reservation, slotted Aloha and hybrid mechanisms are used and are configurable on a per-port basis, enabling customers to run multiple applications simultaneously. Voice of 5.6 kbit/s Hughes-proprietary CELP compression as well as voice of 8/16 kbit/s ADPCM compression schemes, synchronous data of 1.2 to 64 kbit/s, asynchronous data of up to 19.2 kbit/s and G3 fax relay are some of the applications.

The satellite links are often referred to as long fat pipes – they represent paths with high bandwidth-delay product. Moreover, since they typically provide a broadcast channel, media sharing methods are needed at the MAC sublayer of the data link control layer. The traditional CSMA/CD schemes typically used in LANs can not be used with satellite channels since it is not possible for earth stations to do carrier sense on the up-link due to the point-to-point nature of the link. A carrier-sense at the downlink informs the earth stations about potential collisions that may have occurred 270 ms ago (for GEO). Such delays are not practical for implementing CSMA/CD protocols. Most satellite MAC schemes usually assign dedicated channels in time and/or frequency for each user. This is due to the fact that the delay associated in detecting and resolving multiple collisions on a satellite link is usually unacceptable for most applications.

The VSAT services are primarily based on one of two technologies: i. Single-carrier per channel (SCPC) and ii. Time-division multiple access (TDMA).

3.5.1. SCPC (Single-Carrier Per Channel)

SCPC-based design provides a point-to-point technology, making it the VSAT equivalent to conventional leased lines.

VSAT

3.5.2 TDMA (Time-division multiple access)

With TDMA networks, numerous remote sites communicate with one central hub – a design that is similar to packet-switched networks. As a leased-line equivalent, SCPC can deliver dedicated bandwidth of up to 2 Mbit/s. Remote sites in a TDMA network compete with one another for access to the central hub, restricting the maximum band-.4 – DE width in most cases to 19.2 kbit/s. Almost all international VSAT services in Asia-Pacific are based on SCPC. Most domestic offerings are based on TDMA, although some domestic operators offer point-to-point SCPC links as well. Here, we will discuss briefly TDMA, pre-assigned or demand-assigned FDMA, CDMA and other accessing techniques featuring merits and demerits of these schemes.

In a TDMA network, all VSATs share satellite resource on a time-slot basis. Remote VSATs use TDMA channels or inroutes for communicating with the hub. There could be several inroutes associated with one outroute. Several VSATs share one inroute hence sharing the bandwidth. Typical inroutes operate at 64 or 128 Kbit/s. Generally systems with star topology use a TDMA transmission technique. Critical to all TDMA schemes is the function of clock synchronization what is performed by the TDMA hub or master earth station. The VSATs may also access the inroute on a fixed assigned TDMA mode, wherein each VSAT is allocated a specific time slot or slots.

VSAT

3.5.3 FDMA (Frequency Division Multiple Access)

It is the oldest and still one of the most common methods for channel allocation. In this scheme, the available satellite channel bandwidth is broken into frequency bands for different earth stations. This means that guard bands are needed to provide separation between the bands. Also, the earth stations must be carefully power-controlled to prevent the microwave power spilling into the bands for the other channels. Here, all VSATs share the satellite resource on the frequency domain only. Typically implemented in a mesh or single satellite hop topology, FDMA has the following variants:

i. PAMA (Pre-Assigned Multiple Acceess)

It implies that the VSATs are pre-allocated a designated frequency. Equivalent of the terrestrial leased line solutions, PAMA solutions use the satellite resources constantly. Consequently, there is no call-up delay what makes them most suited for interactive data applications or high traffic volumes. As such, PAMA connects high data traffic sites within an organization.

SCPC (Single Channel Per Carrier) refers to the usage of a single satellite carrier for carrying a single channel of user traffic. The frequency is allocated on a pre-assigned basis in case of SCPC VSAT which is also synonymously known as PAMA VSAT.

ii. DAMA (Demand Assigned Multiple Access)

The network uses a pool of satellite channels, which are available for use by any station in that network. On demand, a pair of available channels is assigned so that a call can be established. Once the call is completed, the channels are returned to the pool for an assignment to another call. Since the satellite resource is used only in pro-portion to the active circuits and their holding times, this is ideally suited for voice traffic and data traffic in batch mode. DAMA offers point-to-point voice, fax, and data requirements and supports video-conferencing. The ability to use on-board signal processing and multiple spot beams will enable future satellites to reuse the frequencies many times more than today’s’ system. In general, channel allocation may be static or dynamic, with the latter becoming. DE – 5 increasingly popular. DAMA systems allow the number of channels at any time be less than the number of potential users. Satellite connections are established and dropped only when traffic demands them.

VSAT

iii. CDMA (Code Division Multiple Access)Under this, a central network monitoring system allocates a unique code to each of the VSATs enabling multiple VSATs to transmit simultaneously and share a common frequency band. The data signal is combined with a high bit rate code signal which is independent of the data. Reception at the end of the link is accomplished by mixing the incoming composite data/code signal with a locally generated and correctly synchronized replica of the code. Since this network requires that the central network management system co-ordinates code management and clock synchronization of all remote VSATs, star topology is, by default, the best one. Although this is best applicable for very large networks with low data requirements, there are practical restrictions in the use of spread spectrum. It is employed mainly for interference rejection or for security reasons in military systems.

VSAT Accessing Schemes

TDMATime-

division Multiple Access

TDMATime-

division Multiple Access

FDMAFrequencFrequenc

y y Division Division Multiple Multiple AccessAccess

FDMAFrequencFrequenc

y y Division Division Multiple Multiple AccessAccess

SCPCSingle-Single-carrier carrier

per per ChannelChannel

SCPCSingle-Single-carrier carrier

per per ChannelChannel

VSAT TECHNOL

-0GY

VSAT TECHNOL

-0GY

DAMDAMAA

CDMCDMAA

PAMAPAMA

FDMA

VSAT

4.0. VSAT NETWORK CHARACTERISTICS

Modern satellites are often equipped with multiple transponders. The area of the earth’s surface covered by a satellite’s transmission beam is referred to as the “footprint” of the satellite transponders. The up-link is a highly directional, point-to-point link using a high-gain dish antenna at the ground station. The down-link can have a large footprint providing coverage for a substantial area or a “spot beam” can be used to focus high power on a small region thus requiring cheaper and smaller ground stations. Moreover, some satellites can dynamically redirect their beams and thus change their coverage area. The received microwave power involved in satellite links is typically very small (of the order of 100 picowatts). This means that specially designed earth stations that keep carrier-to-noise ratio to a minimum are used to transmit/receive satellite communications. The front-end receiver is the most crucial part of a transceiver and contributes to the overall cost of the satellite earth station in a significant way. Here, we describe some of the characteristics of a VSAT network:

4.1. Flexibility

The VSAT networks offer enormous expansion capabilities; it factors in changes in the business environment and traffic loads that can be easily accommodated on a technology migration path. There are limitations faced by terrestrial lines in reaching remote and other difficult locations. On the other hand, VSATs offer unrestricted and unlimited reach. Additional VSATs can be rapidly installed to support the network expansion to any site, no matter however remote.

4.2. Network Management

Network monitoring and control of the entire VSAT network is much simpler than a network of leased lines, involving multiple carriers at multiple locations. A much smaller number of elements need to be monitored in case of a VSAT network and also the number of vendors and carriers involved in between any two user terminals in a VSAT network is typically one. This results in a single point of contact for resolving all your VSAT networking issues. A VSAT network management system easily integrates end-to-end monitoring and configuration control for all network subsystems.

4.3. Reliability

A single-point contact for operation, maintenance, rapid fault isolation and trouble-shooting makes things very simple for a client, using VSAT services. VSATs also enjoy a low mean-time to repair (MTTR) of a few hours, which extends up to a few days in the case of leased lines. Essentially, lesser elements imply lower MTTR. Uptime of up to 99.5

VSAT

percent is achievable on a VSAT network. This is significantly higher than the typical leased line uptime of approximately 80-85%.

4.4. Cost

A comparison of costs between a VSAT network and a leased line network shows that a VSAT network offers significant savings over 2-3 years timeframe. This does not take into account the cost of downtime, inclusion of which would result in the VSAT network being much more cost-effective. Pay-by-mile concept in case of leased line sends the cost spiraling upwards. More, so if the locations to be linked are dispersed all over the country. In case of VSATs, the service charges depend on the bandwidth which is allocated to the network in line with customer requirements. With a leased line, a dedicated circuit in multiples of 64 kbit/s is available whether the customer needs that amount of bandwidth or not.

4.5. Link Budgets

It ascertains that the RF equipment would cater to the requirements of the network topology and satellite modems in use. The link Budget estimates the ground station and satellite EIRP required. Equivalent isotropically radiated power (EIRP) is the power transmitted from a transmitting object. Satellite ERP can be defined as the sum of output power from the satellite’s amplifier, satellite antenna gain and losses. Calculations of signal levels through the system (from originatin earth station to satellite to receiving earth station) to ensure the quality of service should normally be done prior to the establishment of a satellite link. This calculation of the link budget highlights the various aspects. Apart from the known losses due to various cables and inter-connecting devices, it is advisable to keep sufficient link margin for various extraneous noise which may effect the performance. It is also a safeguard to meet eventualities of signal attenuation due to rain/snow. As mentioned earlier a satellite provides two resources, bandwidth and amplification power. In most VSAT networks, the limiting resource in satellite trans-ponder is power rather than bandwidth.

VSAT

5.0 IMPLEMENTATION OF VSAT TECNOLOGY IN MALAYSIA

Many projects had started and implemented by provider such as Telekom and Maxis.

• Rural Communities (E-Bario, schools) –telephone and internet

• Esso Malaysia, Shell Trading, Caltex – data application

• Bernama

• Felda Palm and Transport

• Petronas Carigali & Dagangan

• Ericsson, Motorola

• Standard & Chartered Bank

• Min. of Education and Min. of Health

5.1. E-BARIO Synthesis

The project objective was to define the opportunities for social development which are available from the deployment of Information and Communication Technologies (ICTs) within remote rural communities in Sarawak, using the Smart School as a demonstrator application. To identify further needs and opportunities within such communities that can be satisfied by the innovative use of contemporary ICTs and, through action-oriented measures, to demonstrate how significant and sustainable development can be achieved by remote communities through such implementations.

The project was undertaken against the background of the Government of Malaysia’s aggressive adoption of ICTs for national development and the underdeveloped infrastructure and scattered population of the Nation’s largest state, Sarawak, on the island of Borneo. It has as its rationale the delivery of equal access to ICTs for those remote and marginalised communities that characterise rural life in Sarawak, and which contain more than half of the State’s population. Many such communities are un-served by road and have access to meagre or non-existent telecommunications services. The objectives were to demonstrate that access to ICTs, specifically the Internet, could precipitate significant improvements in the lives of such communities.

The methodological approach was to conduct a pilot telecentre implementation within one remote community. The remote highland community of Bario in northern Sarawak was selected. It has a population of around 1,000 people and is the traditional centre of the Kelabit ethnic group of Borneo, which consists of around 5,000 people. Baseline studies were conducted in order to understand the conditions of life in the chosen

VSAT

community and computers were progressively introduced, beginning with the school. A community telecentre was established with the intention of providing community access to computers and to the Internet. It is also intended to provide the school with access to the Internet. Owing to a variety of circumstances, access to the Internet will not be achieved until after the end of the IDRC project funding period. Nevertheless, as additional funds have been obtained, the project will continue with the same objectives beyond the initial IDRC-funded period.

The project has shown the following results and impacts:

Within the target community of Bario:

A computer laboratory with 10 computers has been established at the junior-secondary school.

An IT Literacy Programme is in operation in conjunction with a local company.

A community telecentre has been established with four computers. Internet access is to be provided by the national

telecommunications carrier, Telekom Malaysia, who have installed satellite dishes and VSAT equipment for the connections to the telecentre and the school.

The community has been sensitised to the capability of the technology and an agenda for development activity based on improved and technology-driven information delivery has been agreed.

Within the wider community of Sarawak and beyond:

The Federal and State governments have been stimulated towards wider deployments of ICTs within rural communities both within Sarawak and the rest of Malaysia.

The project has attracted further funding from the Government of Malaysia.

Public awareness of the potential for ICT-induced rural development has increased.

Universiti Malaysia Sarawak has developed considerable capacity for research into rural development with ICTs, having assembled a vibrant cross-disciplinary team capable of extending their activities beyond the immediate project. The Faculty of Information Technology ran a successful international symposium on rural ICTs and has declared its intention to establish a research centre in rural ICTs.

Methodological aspects of research and advocacy for rural ICTs in developing countries have been advanced.

VSAT

E-Bario Network Diagram

Dialaway VSAT

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5.2. Opportunities in VSAT Technology

For the future technology with the abroad services VSAT many opportunities can be achieved such as;

i. Voice over IP (VoIP) via satellite

ii. Frame Relay via satellite

iii. ATM via satellite

iv. Video-on-demand via satellite

v. Multimedia application– Internet/e-mail connection– Telemedicine– Distance learning

VSAT

6.0 TELEKOM MALAYSIA VSAT – TM VSAT

6.1. TM VSAT

TM VSAT offers highly reliable, flexible support of integrated multimedia communications. Compared to alternative technologies, TM VSAT offers customers the following features and benefits:

i. Star network topology - offers end-to-end shared hub services for network requirements that cannot economically support a dedicated hub and operated by experienced staff to ensure optimum service levels.

ii. Full mesh connectivity - provides a hubless network using only one satellite hop, offers lower delay and better response times. Smaller networks can be implemented at lower costs than traditional hub-based systems.

iii. Bandwidth-on-Demand - architecture automatically allocates a pool of bandwidth to meet customer requirements of any site. The customer can move or add host computers and PABX's without having to re-engineer or re-size the network. Servers may be centralized or distributed. The bandwidth automatically "follows" the new traffic patterns.

iv. Scalability of network capacity - The aggregate network capacity can be increase from time to time as the number of sites and volume per site grows.

v. Modularity and open system architecture - supports modular and open system architecture. The customer can expand the number of interfaces at the indoor unit as he requires.

vi. Economics of statistical multiplexing - Multiple applications share the same bandwidth. The customer uses and pays for less total bandwidth than with the more traditional multiple dedicated network approaches.

vii. Network Management and Control - operating on global standards and operational 24 hours a day, 7 days a week for some of major Earth Stations.

viii.Cost effective solution - provides cot-effective communication solutions with high level functionality and performance since the pricing is distance independent. It offers a competitive alternative even for countries, which have a high degree of communication infrastructure.

VSAT

The dish is small, easily transportable and installation lead-time is much shorter if compared to terrestrial links. In addition, VSAT network allows rapid, low-cost network re-configuration and expansion to meet new or unexpected business requirements. Cost effective transmission and network operations are made possible by use of the C-band satellite frequency and frequency times division multiple access (FTDMA), Frequency division multiple access (FDMA) or Time division multiple access (TDMA) transmission techniques. VSAT offers a wide of protocols and features, providing extraordinary flexibility and virtually unlimited expansion capabilities. In addition, VSAT network is typically engineered to achieve a minimum of 99.5% end-to-end availability for all locations.

6.2. TM VSAT Architecture.

VSAT can customize and implement select topology of network that is best suited to the customers' requirement.

i. Hub type (VSAT HubStar with Star network topology)

ii. Hubless type (VSAT DialNet and VSAT Direct with point-to-point or meshed network topology)

6.2.1. Hub type (VSAT HubStar)

VSAT HubStar is a private network designed for data, multimedia and voice applications, providing highly reliable communications between a central hub and almost any number of geographically dispersed sites. It integrates both high-speed Internet access and video multicasting capabilities. The network is suitable for point to multi-point communication for customers having a single data center requiring connectivity to its branches in geographically dispersed locations. This service supports transmission bandwidth ranging from 9.6 kbps to 128 kbps duplex. One of the advantages of Star topologies is that the hub can maintain effective control of the network through centralized processing. It is well suited for business traffic from the hub at the company headquarters and individual VSATs located at field offices, retail outlets or branches.

6.2.2. Hubless type (VSAT DialNet and VSAT Direct)

VSAT DialNet is a low cost rural telephony and Internet solutions that provides voice, fax and Internet service via satellite. It delivers toll-quality voice and IP transmission and represents the most cost-effective solutions. VSAT Direct is a communication network that provides on-demand data, voice and fax to remote locations via satellite with a flexible multi-channel communications for public, corporate and government applications. The available bandwidth is ranging from 9.6 kbps up to 2048 kbps duplex. Its point-to-point or mesh architecture is useful for providing

VSAT

inter-connectivity amongst relatively high volume VSATs utilization. It supports connection on demand between any pairs or terminals in the system.

6.3. TM VSAT Reachability.

VSAT is a satellite-based service covering national and regional telecommunication needs. The service is served from small parabolic dishes (1.8m/2.4m/3.8m) accessing to the satellite directly from the customer premises. That explains the capability of the service reaching out to challenging areas of the country and region. This means of communication can also serve as part of company's network diversity. Value added services that TM VSAT can offer is as follows:

6.3.1. Gyro Stabilized System

Practical to cater for offshore communication especially for rough and choppy sea condition. A total service package that VSAT can offer to oil and gas customer. Typical applications are data transfer, voice communication and facsimile during oil exploration or drilling activities.

6.3.2. Potential back-up service

Inmarsat as a back up to the existing VSAT service for offshore industry.

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7.0. MAXIS VSAT

VSATs are an ideal means of communication in areas where terrestrial infrastructure is unavailable or unreliable. As such VSAT services are able to bring distant or remote business communities closer by eliminating geographical barriers and challenges that previously existed. This in turn transfers to an increase in productivity and overall cost efficiency for such communities.

In addition to providing communication to remote areas, VSATs are also suitable in providing private networks in urban areas for organisations with many geographically dispersed branches that require connectivity to their Headquarters.

VSAT services generally offer service reliability and availability that is equal to or higher than terrestrial services.

7.1. Type of Maxis VSAT Services

7.1.1. SkyNet (TDM/TDMA) Services

SkyNet service provides a private data network connectivity from the customer's HQ via leased lines to a central earth station (or the VSAT hub) to clusters/ groups of VSATs located at the customer's distant branch offices.

SkyNet service which is based on another well-proven TDM/ TDMA (Time Division Multiplexed/Time Division Multiple Access) VSAT technology, is most suitable for organisations that need to transfer time critical, interactive applications that are "bursty" in nature between a head office or central data processing facility, and many outstation branch offices nationwide or regionally.

The TDM/ TDMA network architecture is deployed as such that a single (or multiple) outgoing (TDM) broadcasting channel carries all the data destined for each of the distant VSAT. The outgoing channel is simultaneously received by all of the distant outstation VSAT terminals whereby each individual terminal will then "extract" the data addressed to them and discards the rest.

Each distant VSAT terminal communicates with the HQ by requesting a (TDMA) return channel (one of many) to close out the transaction. On completion, the TDMA return channel is then relinquished to a common resource pool awaiting the next requests from other VSAT terminals.

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7.1.2. SkyLine (SCPC) Services

SkyLine is a VSAT service that provides a dedicated point-to-point/ multipoint connectivity between any two sites within the coverage or footprint of communication satellites including MEASAT satellites. It uses the well-proven SCPC (Single Channel Per Carrier) VSAT technology whereby one frequency channel on the satellite transponder is dedicated to a single link between two locations. SkyLine service transmits data continuously between two locations via the satellite at a high rate of up to 8.192Mbps in multiples of n x 64Kbps.

There are two types of configurations for a SkyLine VSAT link:

i. Hub-to-Remote ConfigurationIn the Hub-to-Remote configuration, one end of the VSAT link (normally the customer's HQ) is connected to the Maxis' 11-meter VSAT Hub (Earth Station) via a terrestrial leased line. A VSAT antenna at the remote end or the distant end (normally the branch office) of the VSAT link is then interconnected to the VSAT hub via the satellite.

ii. Remote-to-Remote ConfigurationVSAT links with a Remote-to-Remote configuration bypass the Maxis VSAT Hub and has a stand-alone VSAT antenna at both ends of the link. Typical VSAT antenna size ranges from 1.8m to 2.4m.

7.1.3. SkyLine-Plus (SCPC) Services

SkyLine-Plus is an extension of the SkyLine service using the well-proven SCPC (Single Channel Per Carrier) VSAT technology. The extended features that SkyLine-Plus has over SkyLine is that it allows the following network flexibility:

Dedicated bandwidths in a point-to-multipoint configuration (i.e. one to many);

Asymmetrical transmission between one-to-many locations or one-to-one location;

Allows partial or full mesh configuration (any-to-any locations) depending on user needs; and

Effective bandwidth utilisation by way of transmitting integrated voice, data, video and multimedia applications over each dedicated bandwidth

The key feature of SkyLine-Plus service is that dedicated bandwidths can be configured in an asymmetrical manner with high data rates of up to 8.129Mbps and in multiples of n x 64Kbps

7.1.4. Gyro-Stabilised VSAT Services

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Specialised VSAT service called Gyro-stabilised VSAT is particularly suitable for maritime communications, enabling ship-to-ship and ship-to-shore communications, and communications to and from offshore oil platforms. The Gyro-stabiliser is equipped with an automatic antenna stabiliser and satellite tracking features to provide dependable communications in hostile weather conditions such as high seas (e.g. offshore oil rigs), and vibration typically from the ship turbines (e.g. oil tankers, cruise ships, work barges).

Organisations operating in such unpredictable maritime environment can use the Gyro-stabiliser terminal to support the SkyNet, SkyLine or SkyLine-Plus VSAT services.

7.2. Benefit of MAXIS VSAT Services

7.2.1. Rapid Deployment

Companies wishing to expand their branch operations can do so quickly anywhere within the MEASAT-1 or MEASAT-2 satellites' coverage areas or footprints. VSAT can be rapidly deployed to geographically dispersed sites within weeks compared to months or years with traditional communication infrastructure. VSAT enables you to:

i. Serve your customers in markets you are unable to traditionally serve, such as areas lacking in terrestrial communications infrastructure, which can be sub-urban or rural.

ii. Operate branches nationally or in other countries without being concerned with the number of telecommunications providers you are dealing with.

7.2.2. Competitive Costs

Unlike traditional terrestrial services, the monthly charge for VSAT services is distant independent. Whether sites are 50km or 1000km away, you pay the same for VSAT services. The fixed and competitive pricing ensures that there is no annual budget overruns.

7.2.3. Flexible Network Expansion and Configuration

The size of VSAT networks can be readily expanded or reduced depending on business operations needs, with an end-to-end control.

7.2.4. High Reliability and Availability

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VSAT networks offer high reliability since the points of failure is limited to just two points, i.e. any two locations in a communication link. Least points of failure ensures minimal downtime and the service availability for VSAT networks averages at 99.85%

7.2.5. Centralised Network Management

Overall network management at the central hub keeps track of the status of all network elements, with single point of contact for all network issues. Hence, any outages can be detected early and faults proactively and promptly rectified.

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8.0. EVOLUTION OF MALAYSIA MEASAT

8.1. MEASAT

As Malaysia's first satellite system, the Measat system is specifically designed for both broadcasting and communications services. The system is enhancing Malaysia's ability to acquire many new voice, data and video services. Very Small Aperture Terminal (VSAT) technology, for example, is opening the door to simultaneous transmission of video, data and voice over a single line.

In December 1997, Binariang Satellite Systems Sdn Bhd - the Binariang Bhd subsidiary that owns and operates Measa t- was conferred with Multimedia Super Corridor (MSC) status by the Multimedia Development Corporation (MDC).

8.2. Ground Segment

The Measat system comprises a satellite control centre located at Gunung Raya, Pulau Langkawi Kedah, in Malaysia. The centre is equipped with two 11-metre (m), two 8m, and one 7m antenna. Measat space operations include:

• Operation of the spacecraft;

• Control of the communications equipment configuration;

• Maintenance of the satellite ground equipment;

• Maintenance of the spacecraft's orbit and altitude within the specified limits; and

• Maintaining a posture suitable for timely response to spacecraft and ground equipment anomalies.

The heart of Binariang Communications Services is located at the Subang Hi-Tech facility in the Subang Hi-Tech Industrial Park, Shah Alam.

i. Measat-1An Ariane-4 launched Measat-1 on 13 January 1996 from Kourou, French Guyana. The spacecraft, the first Malaysian-owned satellite, was deployed at 91.5 degrees East. Measat-1 is a BSS-376, built by Boeing Satellite Systems (previously known as Hughes Space and Communications) and has a design lifespan of 12 years. The payload is equipped with 12 36MHz transponders that operate in the C-band. The satellite covers Malaysia, Central and Southern Asia.

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ii. Measat-2 The second spacecraft of the Measat fleet is a BSS-376 satellite launched from Kourou, French Guyana on 14 November 1996 by Ariane-4. The satellite, with a lifespan of 12 years, provides service throughout Southeast Asia from the orbital slot 148 degrees East. Measat-2 carries 12 72MHz C-band transponders.

In October 2001, Transvision International Teleport of Hawaii signed an agreement with Binariang Satellite Systems to provide teleport and Internet services to the Malaysian satellite carrier. Transvision will provide Measat-2 with Internet access to the West Coast and the North American Internet backbone at rates up to 155Mbit/s.

iii. Measat-3Binariang plans to launch the Measat-3 satellite sometime in Q4 2002, using an Ariane-4 or Ariane-5 launch vehicle. An orbital slot of 91.5 degrees East has been allocated.The satellite has a lifespan of 15 years and the payload will comprise of C-, Ku- and Ka-band transponders. The Measat-3 C-Band payload will cover Africa, the Middle East, Eastern Europe, Asia and Australia.

The Satellite will be used for Digital Data Terminal Unit (DDTU) broadcast, analogue TV, Digital Audio Broadcast (DAB), VSAT, telephony, Satellite News Gathering (SNG), trunking, data broadcasting, business network, Internet services, high-speed data rate and multimedia applications.

The Measat-3 Ku Band payload has been designed to provide high-powered flexible service options for the development of direct-to-home applications in China and India and supplement Measat-1 and Measat-2 Ku band capacity over Malaysia, Indonesia, India, the Philippines, Vietnam, Taiwan and Australia.

iv. Africa-Mea SatIn August 2001, Malaysia offered African countries the use the Africa-Mea satellite (A-M Sat) due to be launched in 2004. The total cost of the satellite is around US$200 million. A-M Sat will employ a payload of 24 C-Band and 12 Ku-Band transponders, each providing 36Mhz of bandwidth over its 15-year operational life. A-M Sat will be designed to interconnect with the existing Measat network through Measat-3.

v. India-Mea Sat Plans are underway for another satellite, which is to be called India-Mea Sat.

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9.0. CONCLUSION

The network of VSATs at different locations adopts different topologies depending on the end applications traffic flow requirements. These topologies could be star, mesh or hybrid networks.

The primary objective of the VSAT networks is to maximize the use of common satellite and other resources amongst all VSAT sites. The methods by which these networks optimize the use of satellite capacity, and spectrum utilization in a flexible and cost-effective manner are referred to as satellite access schemes. Each topology in VSAT is associated with an appropriate satellite access scheme. Good network efficiency depends very much on the multiple accessing schemes. There are many different access techniques tailored to match customer applications.

The evolution in satellite communication will be affected to VSAT services.Satellite technology improvements give longer life, greater flexibility, higher performance and higher reliability overall and new on-board technology implementations. While in the ground station developments for improving satellite access technologies will make lower space segment utilization and lower operational costs. The smaller and highly integrated terminals provide more opportunity for mass deployment. Volume production and lower costs will make satellite alternative for multimedia services.

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References

1. http://www.tmdata.com.my/BANDWIDTH-vsat.htm, Communication Without Limits, Telekom Data services, 2002

2. http://www.maxis.com.my/corporate/satellite/gyro.asp, VSAT Services, July 2003

3. Internet Access by Remote Communities in Sarawak: The Smart School as a Demonstrator Application, A Research Project: Universiti Malaysia Sarawak, May 2001

4. http://www.marketinfo4me.com/Satellite%20Evolution%202003/ Section_1/s1_Binariang.htm, Binariang Satellite System – Measat, Satellite Evolution Asia, 2003

5. Presentation on Telekom Malaysia, Satellite Network, August 2001

http://www.marketinfo4me.com/Satellite%20Evolution%202003/

http://www.maxis.com.my/corporate/satellite/gyro.asp

http://www.tmdata.com.my/BANDWIDTH-vsat.htm

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