International Roaming Research Articles

GSM Security

From the early days of mobile phone communications, modern mobile networks offer impressive features and capabilities that were only dreamt about 15 years ago. Mobile phones, once considered a luxury, are now owned by millions worldwide. Through technology improvements and new, advanced protocols, modern cell phones offer international roaming, data connectivity, instant messaging, and emergency services.

Roaming free?: Roaming network selection and inter-operator tariffs

International roaming – the ability to use one's mobile phone on foreign networks – has contributed to the success of GSM services in Europe, but has also been a constant concern for competition authorities. Whilst competition for subscribers has driven down the cost of owning and using mobile phones, roaming charges have remained high, and have been the subject of investigation for example by the European Commission. However, in order to see whether high roaming charges are indeed the result of failing competition, and in order to identify appropriate remedies, one needs to understand how technological constraints impact on competition in the provision of roaming services. In particular, the limited ability to direct roaming traffic onto a particular network implies that price competition at the level of inter-operator tariffs (IOTs) is muted. In this paper, we model competition in the provision of-wholesale roaming services, and its implications for retail offers, depending on the ability to direct roaming traffic onto particular partner networks. We examine the impact of cross-border mergers which are often seen to improve an operator's ability to offer seamless roaming service across an increasing number of countries as a result of an enlarged footprint.

Performance improvement of international roaming service ‐ A benchmarking study

This paper discusses some concepts between quality performance and benchmarking. It explains the conduct of a benchmarking study in international roaming service of the telecommunications industry, and illustrates the benchmarking process in a telecommunication service provider – Cable & Wireless HKT based in Hong Kong. By comparing the service provisioning and fault handling processes with two best‐in‐class companies, the collected data was manipulated in order to position the current performance gaps and project the future performance level. The results suggest that the roaming service providers should establish a service level agreement with their partners and customers, and develop facilities of test activity list and customer acceptance test. In addition, they should employ appropriate performance indicators and measurements, establish direct communications with partners and customers, and monitor the market trend and responses of the roaming technologies and services.

International roaming charges: over-charging and competition law

International roaming is a major technical achievement of the GSM standard. Initially, users were impressed by the technical facility that a mobile phone would work initially across the European Union (EU) and in many other countries, and with a tri-band phone, in North America. Estimates of the market size at the end of 1999 were in the range of US$ 1000 million, with continuing rapid growth. However, users quickly realized that the costs of international roaming were far higher than could be justified. At a time when fixed telecommunications costs and prices were falling, the prices for mobile roaming were spiralling out of control. The response from user organizations has been to withdraw phones, to forbid their use abroad and to encourage alternatives, such as phone-cards and visits to local offices. A series of surveys by INTUG in 1999 and 2000 gathered comparative data on international roaming charges in Europe. The results showed price variances of 2–10 times for the same or a similar call. These data have attracted the interest of the Competition Directorate-General of the European Commission and a formal investigation has been initiated. A decision is expected in late-2000, which could have influence outside the EU, since the principles of competition law, and the terms of international roaming agreements are similar around the world. The indications are that the complexity of the charges, the backroom negotiations and other factors demonstrate that this is very far from being a competitive market. As the GSM Association begins to create a Global Roaming Forum to prepare for 3G (UMTS) roaming, it is clear that a more open and competitive regime is essential if the prices are to be driven down to reasonable levels. That in turn is necessary if we are to see the innovations in uses necessary for the next stage of the development of the mobile telecommunications industry and mobile–Internet convergence.

The making of global standards in the GIS of the 21st century

The global information society has undergone dramatic development in the 90s. The rapid growth in mobile telecommunications and internet business is living proof of a radical change in today's information society and infrastructure. The next emerging phases in this development chain are the continued increase in total mobility with wideband data services. For fixed networks, capacity increase is essential; the new broadband ATM network will be needed to meet bandwidth-hungry end-user applications. In this rapidly changing development phase, traditional standardization organizations and bodies are facing new challenges and increasing demands from both society and industry. Initiatives for new systems and solutions are today specified and agreed upon in market driven cooperation bodies such as the IETF (Internet Engineering Task Force), ATM Forum, DVB, etc. The role of standardization organisations has developed primarily into the provision of documentation, maintenance and version updates. A large number of ad hoc forums present a risk however. It may be problematic for these different bodies to understand the whole picture of interfaces to other existing standards. Another equally important issue for them is the overall understanding of end-user needs. Business opportunities and market development on the other hand, are demanding fast and practical solutions with equal access to all market players. The main challenge in the future development of next generation mobile standard lies in the question: are we able to create and agree upon a global standard? The Global System for Mobile Communication, GSM, is a good example of an excellent cooperation in standardization work. Many strengths—open interfaces, true international roaming with a well-developed terminal market—have made GSM the most successful communications system in the world. This will enable a natural migration path towards next generation mobile technology. To fulfil the subscriber needs, GSM today offers the widest range and variety of services. Currently, (June 97) more than 44 million people use GSM phones with services offered by more than 230 operators in well over 100 countries in all continents, increasing by 2 million users each month at present. By the year 2000, there will be more than 200 million GSM subscribers. New business opportunities and markets will open when customer-driven applications in the networks are growing. Enhancement of new services such as electronic payment systems and personalized multimedia are crucial in building the next generation global information society.

Numbers and identities for emerging wireless/PCS networks

In order to support mobility management functions in wireless/PCS networks and provide national and international roaming, well defined, standardized subscriber/terminal numbers and identities are required. Some form of station equipment identities are also needed to ensure that service is denied to non-type-approved or stolen terminals. The article provides an overview of existing standards and current usage of numbers and identities in mobile networks, and their application and planned evolution to support a range of terminal and personal mobility services as PCS networks and services are introduced.

Traffic impacts of international roaming on mobile and personal communications with distributed data management

In this paper, we propose four network interconnection scenarios and the related signaling aspects for the international roaming traffic in mobile and personal communications. With or without international gateway relay nodes summarized from the proposed scenarios, we also derive three international roaming network sets {IR1, IR2, IR3} for the observed signaling traffic model with two-level databases. Based on the proposed performance metrics, analysis results show that under some reasonable assumptions the signaling traffic of international roaming is significantly impacted by the related gateway relay nodes and databases. In addition, the studied cache data management strategy at VLR can reduce the impacts of the signaling traffic of query operation, but the caching approach cannot improve the performance of update operation. Furthermore, the performance of proposed standalone STP scenario is better than that of integrated STP scenario for the international network connection.

Mobile secure telephones

Describes GSM, a TMDA digital radio system which has more than 120 operators in over 60 countries and allows international roaming with only a contract between operators to initiate the agreement. Details the security services provided for the protection of legitimate users, the measures taken to exclude unauthorized users and the procedures implemented to minimize international roaming problems.

The pan‐European mobile radio system: Part II

AbstractHaving considered the mapping of logical traffic and control channels onto physical channels, speech and error correction coding, interleaving as well as the TDMA hierarchy and synchronisation problems in Part I of this contribution, here mainly transmission issues are addressed [1–6] and some performance figures are provided. Constant envelope partial response Gaussian Minimum Shift Keying (GMSK) with a channel spacing of 200 kHz is deployed to support 125 duplex channels in the 890 ‐ 915MHz uplink and 935 ‐ 960 MHz downlink bands, respectively. At a transmission rate of 271 kbit/s 1.35 bit/s/Hz spectral efficiency is achieved. The controlled GMSK‐induced and un‐controlled channel‐induced inter‐symbol interferences are removed by the channel equaliser. The set of standardised wide‐band GSM channels is introduced in order to provide bench‐markers for performance comparisons. Efficient power budgeting and minimum co‐channel interferences are ensured by the combination of adaptive power‐ and handover‐control based on weighted averaging of up to eight uplink and downlink system parameters. Discontinuous transmissions (DTX) assisted by reliable spectral‐domain voice activity detection (VAD) and comfort‐noise insertion further reduce interferences and power consumption. Due to ciphering, no unprotected information is sent via the radio link. As a result, spectrally efficient, high‐quality mobile communications with a variety of services and international roaming is possible in cells of up to 35km radius for signal to noise‐ and interference‐ratios in excess of 10 ‐ 12 dBs.

C 900—An advanced mobile radio telephone system with optimum frequency utilization

The paper presents a survey of a new approach to advanced system solutions for mobile radio telephone systems. It is shown that, by the combination of both radio techniques and microprocessor data capabilities, improved means are available for controlling the specific multiple propagation and interference influences within the mobile radio environment. The aim of the system structure is to achieve the best possible frequency channel utilization, system availability, and cost benefits for deployment and users if traffic demand grows. The paper shows the different types of switching functions in public land mobile networks. Problems, as caused purely by radio conditions, are controlled within a defined radio exchange function, allowing the optimization of individual cell parameters. It is shown that distance measurement is the most reliable means of detecting cell boundaries. New approaches for system control channels lead to synchronous operation of base stations. The system operates with off-air call setup and queueing to improve channel utilization. Full national and international roaming capabilities are provided. During all calls, continuous digital link control is maintained to allow the radio exchange function in call condition. This new approach leads to different types of handoff to suit specific situations. Speech scrambling provides subscriber privacy.

C 900 - An Advanced Mobile Radio Telephone System with Optimum Frequency Utilization

The paper presents a survey of a new approach to advanced system solutions for mobile radio telephone systems. It is shown that, by the combination of both radio techniques and microprocessor data capabilities, improved means are available for controlling the specific multiple propagation and interference influences within the mobile radio environment. The aim of the system structure is to achieve the best possible frequency channel utilization, system availability, and cost benefits for deployment and users if traffic demand grows. The paper shows the different types of switching functions in public land mobile networks. Problems, as caused purely by radio conditions, are controlled within a defined radio exchange function, allowing the optimization of individual cell parameters. It is shown that distance measurement is the most reliable means of detecting cell boundaries. New approaches for system control channels lead to synchronous operation of base stations. The system operates with off-air call setup and queueing to improve channel utilization. Full national and international roaming capabilities are provided. During all calls, continuous digital link control is maintained to allow the radio exchange function in call condition. This new approach leads to different types of handoff to suit specific situations. Speech scrambling provides subscriber privacy.