|Asia-Pacific II 2003
|‘Real’ Teledensity Solution Based on WLL
|Raghu Rao and R Balajee
|Vice-president, Business Development and Manager, Telecom & Software Group
|Midas Communication Technologies
Raghu Rao is the Vice-president of Business Development at Midas Communication Technologies and is also responsible for the Sales & Marketing of corDECT and optiMA worldwide. Before joining Midas, Raghu served as the General Manager, Business Development of Sierra Optima Ltd and led its entry into the European markets through an office in the UK. Mr Rao was also the founder of Merlinhawk Associates Ltd, a pioneer in fibre optic networking in India and Merlinhawk Communications Ltd, which manufactured custom-built repeaters and multiplexers. Mr Rao holds a Bachelors Degree in Electrical Engineering from REC, Kurukshetra, He earned his MBA at the University of Nottingham’s School of Management and Finance, in the United Kingdom. R Balajee is the Manager of the Telecom & Software Group at Midas. He worked in the Development and Engineering department at W.S. Telesystems, before his involvement with corDECT. He has been involved in the development of corDECT, India’s first indigenous Wireless Access System from its conception. Mr Balajee received his Engineering degree in Electronics and Communication Engineering from Madras University.
Communication technology and ICT penetration in countries such as India is far below international standards. This has a devastating impact upon these countries’ socio-economic development. The cost and difficulty of providing ‘Last mile’ access to rural users is one of the major reasons that communications services do not reach these areas. Wireless Local Loop (WLL) networks replace costly wired connections with more cost-effective wireless links. DECT technology provides flexible, low-cost, easily deployed, WLL last mile voice and data access.
The Growing Markets – the Poor and Needy The potential for Information and Communication Technologies (ICTs) to enhance socio-economic development is recognised worldwide. To bridge the digital divide, national governments, NGOs, corporations and global organisations such as the UN and the G8 are all marshalling resources to use ICTs for regional development. Telecoms infrastructure is a basic precursor to the effective use of ICTs, which are seen as an enabling tool that can cut costs and improve the quality and delivery of a wide variety of basic infrastructure and services. This prospect of economic growth would, it is hoped, stimulate the financing for government programmes. Teledensity is a measure of the penetration of telecom use and an indicator of a region’s telecommunications infrastructure. Teledensity is not an exact measure of household telecom penetration so other parameters are needed to understand the contribution of the telecom sector to socio-economic integration. In India, teledensity — telephone lines per 100 persons — reached five, by March 31, 2003. Nevertheless, there were wide disparities in the penetration between rural and urban areas shown by Department of Telecommunications’ (DoT) statistics. The penetration in urban areas of 15.16, but only 1.49 in rural regions indicates that the current teledensity will not be sufficient to usher in the ICT (information and communication technology) revolution. In India, according to the 2001 census, only 28 per cent of the population live in urban areas, the remainder live in rural regions with minimal telecom penetration. Teledensity – A Multi-dimensional Problem The obstacles to increasing teledensity are financial, technological, political and geographical. Liberalisation of the telecommunications sector is generally seen as the key to improving teledensity since this will stimulate investment in the sector. Local investors have been overlooked, but they have substantial potential to provide financing if an appropriate investment climate can be established. This is particularly true in the rural areas of the country. Since in most of the developing countries across the world, the teledensity initiatives have been based upon initiatives by developed countries, the approaches to dealing with the complex range of issues tend to be superficial. Often, external pressure to liberalise a country’s telecom sector is mainly aimed at helping the large multinational companies gain access to their markets. To solve the problem of teledensity, technology that meets local needs, is simple enough to be managed by the local populace and could be financed locally if needed. The technology should really help integrate the population into the information society and the ICT revolution. The investment that the local operator makes in technology and infrastructure should meet both current and future needs of the sector and should, in short, be ‘future-proof’. Generally, solutions for long-term needs require heavy investment, but for the operator the problem is, precisely, the amount of investment required. Despite the low initial costs, operators cannot afford cheap technologies that will not meet future needs. Conversely, they cannot afford higher costs for technologies likely to meet long-term future needs. This is the investment paradox operators face when attempting to solve the teledensity problem. Why DECT? Wireless Local Loop (WLL) technology is a relatively inexpensive way to build fixed networks. WLL services must provide good voice and data capabilities to be effective. Hence, WLL that is simply a modification of mobile technology has, for the most part, not proved to be effective in the long run. Unlike primary mobile technologies, DECT evolved as a landline cordless communication system. DECT is a generic radio access system that interfaces with local and/or public networks (POTS, ISDN, GSM or LAN). Mobile telephony systems such as GSM, on the other hand, are complete public network telephony systems providing specific services. The DECT interface unit translates signals between the systems, thus allowing the DECT terminal to work in the same way as the host system – a GSM phone, for example, if the DECT base station is linked to a GSM network. When the base station instead is connected to an ordinary fixed telephone system (POTS), the terminal will act as a conventional wired phone; DECT provides perfect access to any sort of system. DECT, at the systems level, offers versatile WLL solutions. By design, it requires minimal radio planning. This is due to the Multi-Carrier Multi-TDMA radio access method, combined with Dynamic Channel Selection (DCS) enabling high capacity and robust operations in difficult radio environments. This method also enables DECT to support a wide range of users. The DACES capability ensures that DECT can coexist with other DECT applications and systems in the same frequency band, whilst still maintaining high-quality, robust and secure communications for end-users. DECT is able to offer a range of bandwidths by combining multiple channels into a single carrier. For data transmission, channels can be combined to provide up to 552 kbps with full security. DECT also offers asymmetric connections, often used for home Internet access, so that large amount of data can be downloaded at high speed and a slower channel used in the other direction. Standardised or proprietary ‘profiles’ permit DECT systems to cater to a wide variety of applications DECT’s Radio Interface design results in simpler transceiver designs and need minimal radio planning. This results in low cost – as low as $30 – DECT ‘air’ interface products. Further enhancements of the air interface are planned which will, in the first phase, increase transmission rates to 7Mbps and, in the second phase by the end of 2003, will boost DECT broadband transmission rates to 20Mbps. Frequency bands have been made available for DECT in more than 100 countries in five continents. Can DECT Serve as a WLL Solution? The low transmission power of DECT systems limits the distances it can cover in WLL applications. Normally, this means that a clear line-of-sight between the user terminal and the base station is needed. Since WLL requirements vary greatly according to the terrain, the surrounding buildings and the like, this is frequently a problem. Often, it is the engineering of the DECT WLL solution that has failed rather than the technology. DECT – properly engineered and deployed to suit the local topology and conditions and taking its low power into account – can be a good solution for WLL. WLL systems are used as a low cost option to leverage the existing infrastructure of incumbents and minimise the total cost of ownership (TCO) of the last mile network. The dimensioning and scalability of these systems, so they are financially viable with limited numbers of subscribers, is an important issue. WLL systems, unlike ordinary wired telephone systems, use intelligent subscriber terminals. With intelligent terminals, deployment of such cannot be handled by the work force that carries out wire line deployment. Good Operational Support Systems (OSS) can economically handle many such problems remotely, but complex problems that are difficult to resolve at a distance, can be costly and easily result in dissatisfied customers. WLL Solutions The range, the distance over which a WLL solution is employed varies greatly from application to application, so coverage must be carefully planned to avoid the failure of DECT based WLL solutions. Propagation delay compensation can extend the range of the base station to 10 kilometres and low-cost DECT-based repeaters can extend the range to 25 kilometres. Dedicated Internet access equivalent to, or better than that of the public switched telephone network is another important feature. Some DECT systems can offer Internet access at 70Kbps. Line-of-sight is another important problem. External antennas in common DECT systems should be no further than a few hundred metres from and with a direct line-of-sight to, the subscriber’s indoor unit. To simplify system deployment and keep costs low, it should also be possible for several subscriber terminals to share a single outdoor unit. By using the existing infrastructure – copper cables, E1 data lines, towers and the like – incumbent operators can expand more rapidly and economically. Base stations and subscriber terminals should, if needed, be able to operate on batteries or solar panels. Competitive carriers can maximise coverage, with minimum infrastructure, by using versions of DECT that provide high capacity coverage and a several kilometre range, from one base station. Both capital and operating expenses must be low enough that the WLL/DECT system will be financially viable with as few as 50 subscribers. An OSS with continuous testing and debugging features, that can give operators early warnings of subscriber problems, is an important feature that helps minimise operating expenses. DECT in the Future In the future, DECT will have to offer data rates of 1-2 Mbps for long-term viability. Each subscriber should be able to obtain dedicated use of, at least, several hundred kbps both upstream and downstream to support applications such as video conferencing, distance learning, telemedicine and e-governance. Applications such as these would improve the standard of living for inhabitants of rural communities. The technology will have to be spectrally efficient, maximise the use of the communications channel by providing services such as VOIP, be simple to deploy, operate and effectively manage and minimise the total cost of ownership.