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You are here:     Home Magazine Asia-Pacific Asia-Pacific II 1999 The Next Generation of Satellite Communications for Asia Pacific

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The Next Generation of Satellite Communications for Asia Pacific

Written by  Ming Louie
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Ming LouieIssue:Asia-Pacific II 1999
Article no.:10
Topic:The Next Generation of Satellite Communications for Asia Pacific
Author:Ming Louie
Title:VP Asia Pacific Business Development
Organisation:Globalstar
PDF size:24KB

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Article abstract

The introduction of Global Mobile Personal Communications by Satellite (GMPCS) systems, which promise to radically advance basic telecommunications services throughout the world, is being closely watched - particularly in countries where the demand for basic communications can only be met through mobile satellite services offered by GMPCS.

 

Full Article

Currently, more than three billion people around the world lack basic phone service. And, according to the International Telecommunications Union, nearly 50 million people are on registered waiting lists for basic telephone service, something many of us take for granted. In China, for example, telephone service is available to less than 5% of the countrys population of 1.2 billion. Given the capital investment and infrastructure additions required to extend the nation-wide land line network, the prospects for extending current phone services are painfully bleak. Rather than wait for fixed-line service, many have signed up for cellular service. The countrys Ministry of Posts and Telecommunications (MPT) currently serves more than 10 million cellular subscribers, and that number is expected to double every four years. But cellular is not a viable option for everyone. Cellular services are concentrated in metropolitan areas and are not being extended to rural communities because of the difficulty in finding investment capital for deserts of low telecommunications capabilities where many companies believe profitable returns can not be achieved. Faced with these challenges, several companies are leveraging satellite technology to develop systems that can efficiently extend terrestrial cellular telephone service and achieve full coverage not only in major metropolitan areas, but also in remote areas. And it can be done without the costs involved in extending the countrys existing wire line infrastructure. GMPCS The installation of cellular systems and satellite-based Very Small Aperture Terminal (VSAT) equipment has increased rapidly as a consequence of the urgent need for telecommunications services in the Asia Pacific region. With such a large base of cellular users, Asia-Pacific nations represent some of the primary target markets for GMPCS systems. Many Asia-Pacific corporations, such as China Telecom and Kyocera, are heavily involved in these ventures as strategic partners and manufacturers with a common goal of universal communications. The first generation of GMPCS systems will aim to provide Plain Old Telephony Services (POTS) on a global basis, with some additional features such as data transmission and short message services. GMPCS providers currently offer a range of cellular phone-style services such as voice mail, conferencing and messaging nearly anywhere in the world. These services enable consumers to access a variety of voice telephony services. Big LEO Systems Big LEOs is the name often applied to global voice and data systems which use low earth orbit (LEO) and/or medium earth orbit (MEO) satellite constellations to deliver low-cost, high quality services such as voice, data transmission, messaging, facsimile and position location. Globalstars service will be delivered through a 48-satellite LEO constellation and is expected to provide wireless telephone services to virtually every populated area of the world. Users will be able to make or receive calls by using hand-held or vehicle-mounted terminals similar to todays cellular telephones (see Figure 1). The system will be fully integrated with existing fixed and cellular telephone networks, enabling the dual-mode handset units to switch from conventional cellular telephony to satellite telephony as required. In remote areas with little or no existing wire line telephony, users will make or receive calls through fixed-site telephones, similar to phone booths or ordinary wire line telephones. Each subscriber terminal will communicate through a satellite to a ground-based interconnection point (a gateway), which will in turn connect into existing telecommunications networks. Business Strategy for a Global Market GMPCS providers follow different business models in setting up service across the globe. Some have chosen a highly centralised approach, setting up operating companies or affiliates inside the various countries they plan to operate. Globalstar has chosen a more de-centralised approach, selecting local service providers and strategic partners in the Asia-Pacific region, in order to bring valuable resources and expertise to the Globalstar team. China Telecom, for example, is the foremost provider of telecommunications services in China, and will act as Globalstars exclusive service provider in China. Globalstar will sell access to its satellite system to a world-wide network of regional and local telecommunications service providers. Each service provider will have the exclusive right to offer Globalstar services in its area of operation and accept responsibility for the marketing and distribution of services. This responsibility carries the need to obtain regulatory approvals as owners and operators of the gateways serving their respective markets. Regardless of their business model, GMPCS providers face many regulatory and licensing issues when trying to operate throughout the world. Fortunately, providers, government agencies and local service providers have worked together under the auspices of the International Telecommunications Union (ITU). In the ITU Memorandum of Understanding (MoU) developed in February 1997, the GMPCS industry and many governments and regulators agreed on the need to reach regional, and preferably global, arrangements on issues related to facilitating the introduction of GMPCS services around the world. To that end, the participants agreed on the need to standardise regulations and work together to harmonise certain technologies, network components and frequency spectrums. Data privacy is another thorny issue toward which the ITU has made significant strides. The participants in the Memorandum agreed to release, to recognised national authorities, all requested data traffic originating in or routed to the national territory, provided this release of data does not interfere with customer confidentiality. While this may seem like a fancy legal dance around the issue of privacy, without this simple understanding satellite service providers would not even be able to take the first steps towards setting up business. While the ITU has made it far easier for GMPCS providers to establish service around the world, it has not resolved every issue. Some of the more perplexing questions facing GMPCS providers as they enter various countries are related to the umbrella issue of licensing between the satellite service provider and the national and local companies that provide telecommunications service in the host country. Ultimately, satellite service providers find they resolve this problem themselves when they define their international business model. Setting up Shop in Asia Globalstar projects that as much as one fifth of its overall subscriber base will be located in the Asia-Pacific region, and expects approximately 600,000 subscribers in the region by the year 2002. The company will install and operate a dozen gateways, or satellite earth stations, in the Asia-Pacific region. These gateways, owned and operated by Globalstars strategic and/or local partners, are the interconnect points between the satellite system, and the land-based network. Gateways are the key to enabling any GMPCS provider to function as a cellular extension or to serve broader functions that may be required in countries with a sparse communications infrastructure. They contain all of the functionality necessary to support local telephony, fax and low-rate data communications as well as a facility for roaming and universal signalling translation and transmission. The gateway is designed in a modular manner to provide flexibility so the system can grow in step with market demand. Gateways can be shared by multiple service providers that benefit from a group investment in common start-up equipment. The gateway interconnects the satellite-based wireless network and the Public Land Mobile Network (PLMN), or links directly into the Public Switched Telephone Network (PSTN). As such, it is a termination point for network transmission and network signalling. The gateway can be connected to the existing PSTN using standard E1/T1 trunk supporting a variety of signalling protocols. In all cases, interoperability between the GMPCS provider and telephone/cellular companies is assured and the subscriber maintains a convenient single point for billing. To connect satellites with terrestrial switching equipment, Globalstar plans to build up to 60 gateways, or satellite earth stations, around the world. The first five gateways have been completed in Aussaguel, France; Yeuoju, South Korea; Dubbo, Australia; Clifton, Texas, United States; and Bosque Allegre, Argentina. Construction and site work is underway at 20 more sites around the world. Globalstar Advantages Local Service Providers Maintain Control: Globalstars architecture is designed to enable all calls to enter into the service providers existing land-based network from the local gateway. This gives the Globalstar service providers additional revenue opportunities and permits local regulatory authorities to exercise their accustomed degree of regulatory control, thereby strengthening Globalstars service provider support and facilitating local regulatory approval. This approach also enables Globalstar to leverage its in-country partners demonstrated marketing strength and experience and access to an established customer base. Minimising Cost and Risk In order to minimise the cost and accelerate deployment, the Globalstar system consists of small satellites incorporating an established repeater design that acts as a simple bent pipe, relaying signals received directly to the ground. The call processing and switching operations take place at ground level, where they are accessible for maintenance and can be easily updated to benefit from continuing technological advances. Path Diversity and Soft Hand-off The Globalstar system will be able to provide services to a wide variety of locations by combining Code Division Multiple Access (CDMA) with the continuous multiple satellite coverage and path diversity. Globalstar utilises a version of CDMA technology based upon the IS-95 CDMA standard for efficient use of satellite resources. This standard utilises QUALCOMMs patented digital transmission methods in which users share time and frequency allocations, each assigned by unique codes. The signals are separated at the receiver by using a correlator that accepts only signal energy from the desired circuit. Undesired signals are ignored. This technology allows a large number of wireless users to simultaneously access a single radio frequency channel, thereby reducing interference and resulting in a many-fold increase in capacity when compared to analogue systems such as Frequency Division Multiple Access (FDMA). Globalstar has adapted a combination of FDMA with CDMA and spread spectrum modulation that enables it to support multiple users simultaneously and to share its allocated frequencies with other CDMA systems. CDMA, combined with the path diversity offered by multiple satellites, can result in higher call quality and fewer dropped calls when handing off between satellites, while minimising interference with other users sharing the same spectrum allocation. Conclusion Handsets will potentially be able to operate with a single satellite in view, although typically two to four satellites will be overhead. Each mobile handset will communicate with as many as three satellites simultaneously, combining the signals received to ensure maximum service quality. As satellites are constantly moving in and out of view, they will be seamlessly added to and removed from the calls in progress, thereby reducing the risk of call interruption.

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