June 1999

The Network Frontier: Wireless Technologies And The Imagination

BY JEFF LAWRENCE

People generally refuse to stay in one place. In the course of a single day, they may spend their time moving within a building or even from one country to another country. To provide truly universal access to people and information this mobility must be supported.

The development and deployment of terrestrial and space-based wireless technologies is a step toward supporting this type of mobility. Combining various wireless and wireline technologies will enable both personal and terminal mobility.

Personal mobility means that the network can locate an individual regardless of where they access the network. Personal mobility is possible when a user "registers" his or her current location with the network by means of either a login, personal id/smart card (similar to what is used in GSM phones) or by carrying their own personal communications device.

Terminal mobility means that a particular appliance, communications device, or terminal can access the network from any geographic location. This terminal may be owned by one person or shared by many people. Terminal mobility is possible if all access points into the network use the same access technology, or if the terminal is able to support and switch between the different access technologies.

CONSTRAINTS AND CATEGORIES
Before we consider how wireless may support mobility (and universal access), we should briefly review some of the constraints unique to wireless. For example, the constraints that apply to wireless devices pose unavoidable difficulties simply because of the physics of radio transmission.

Noise, interference, fading, and power considerations all have an impact on whether a particular technology will be effective for a particular application. The choice of a wireless technology for a particular application depends on factors such as the range over which the device is expected to operate, the number of other wireless devices that are expected to operate within the same area, and the velocity of the device (that is, whether it is being used by someone sitting in a home or someone in a car traveling down a highway).

Wireless technologies tend to be categorized based on the range in which they operate:

1. within a building such as a home or business (pico cell);
2. within a neighborhood (micro cell);
3. within a suburban area (macro cell);
4. across the globe.

As a practical matter, the telecommunications industry has focused on the development of technologies and standards for three areas: homes and businesses (pico cells), cellular (micro and macro cells), and satellite. Home and business wireless technologies have a very small range and are typically connected to the wireline infrastructure via a base station connected to the electric power, phone, cable, or wireless network. Cellular technologies are connected to the wireline infrastructure via base stations and access points. Satellites connect to the wireline infrastructure via ground stations.

PRESENT AND FUTURE WIRELESS TECHNOLOGIES
Today's wireless networks, which are based on second-generation (2G) wireless standards, primarily support voice transmissions. Further, the telephony network connecting the wireless networks is based primarily on circuit-switching technology, which reflects the traditional preoccupation with transmitting voice.

It is generally understood, however, that data - not voice - will soon be the significant driver for increasing bandwidth. As the demand for data bandwidth eclipses the demand for voice bandwidth within the network, the infrastructure will move towards packet- and cell-based technologies. As a result, the wireless infrastructure is evolving to support not only voice but also high-speed packetized data.

For example, General Packet Radio Service (GPRS) technology uses some of the existing telephony, wireless, and Internet infrastructure to provide high-speed data services to wireless users by allowing data from Internet, frame relay, and X.25 networks to be transported over existing 2G wireless networks. GPRS is an important evolutionary step along the path to supporting broadband voice, data, and video services defined by the third-generation (3G) wireless standards.

MARKET OPPORTUNITIES
Two fundamentally different markets are driving wireless opportunities. The first of these markets is defined by developed countries; the second, by developing countries. In developed countries, the basic wireless service is terrestrial, fairly ubiquitous, and offers a fairly high degree of mobility through cellular telephony and paging services. These networks typically support voice services and are starting to develop and deploy data services.

In developing countries the basic telephony infrastructure is not ubiquitous, and penetration rates into the population are low. How low? Consider these figures: Sweden currently has a cellular phone penetration rate of about 160 subscribers per 1000 people. China and India have a combined population of 2.2 billion people, and currently have a cellular phone penetration rate of less than 1 subscriber per 1000 people.

Developing countries are realizing that burying copper wire in the ground or stringing it over telephone poles to offer basic telephony service is time consuming and expensive. So, many developing countries are looking instead towards deploying wireless local loop (WLL) technologies to provide basic telephony services. WLL technologies are much quicker and less expensive to deploy than traditional means.

Together, the developed and developing countries account for the following trends: the increasing ability of the network to support personal and terminal mobility; the increasing demand for information; and the increasing number of people that can or will be able to access the network through wireless technologies. These trends will create many opportunities to offer new applications and services (Table 1).

CHALLENGES
Many advanced wireless applications and services have experienced growing pains. Nevertheless, there is much opportunity for growth. For example, market opportunities for wireless data service providers and users have greatly expanded, thanks to the Internet. The Internet offers easy access to a mass of information and services that didn't even exist a few years ago.

To date, wireless data services have been used primarily for text-based messaging. (The most successful of these services is the Short Messaging Service offered on the GSM network in Europe.) Future services will utilize a combination of voice, paging, e-mail, Web browsing, e-commerce, environmental monitoring and control, and video and multimedia capabilities.

To move these opportunities from the realm of possibility to reality, several things must happen. First, some of the protocol standards that will support the new requirements related to performance, connectivity, mobility, reliability, security, and openness of new applications and services must be completed, deployed, and utilized. Second, and even more important, people with knowledge and some imagination of what the network can do must develop the applications and services that offer something truly useful and valuable to end users.

The current technical and regulatory challenges for the global wireless infrastructure are most apparent at the boundary between the appliances, devices, and terminals and the access infrastructure. There are additional challenges related to the integration of the access infrastructure with the core infrastructure for location management, handoff, and addressing, but these are not as difficult to solve as those related to integrating appliances, devices, and terminals with the access infrastructure.

The various demands related to voice, paging, data, graphics, video, multimedia, and other enhanced services generate a number of difficult challenges for the wireless infrastructure. Compared to data, voice is relatively simple to transmit over a radio link. Non-voice content typically has more stringent throughput, delay, jitter, and privacy requirements which are difficult to provide consistently in a noisy, shared, and congested radio frequency environment.

SOLUTIONS
The challenges of transmitting non-voice content via wireless have been taken up by various industry bodies (Table 2). Several bodies, for example, have interested themselves in challenges related to the access infrastructure.

The successful and widespread deployment of wireless network technologies and services is also dependent on radio interface standards, signaling protocol standards, the transport protocol standards of the core infrastructure, operating environments for service platforms within the network, and (finally) on devices that allow the easy development of applications and services.

Radio Interface Standards
Recently, there has been some industry progress towards agreement on a single flexible standard offering multiple access methods for the radio interface of 3G wireless networks. Satellite constellations operating at different altitudes above earth and within different frequency bands are designed to act as an alternative to the terrestrial wireless network. Some constellations are designed to provide voice services. Others are specifically designed to provide broadband data services such as the Internet.

Signaling Protocol Standards
The signaling protocols for location management and handoff are based on SS7 and its appropriate user and application part protocols. The architecture for 3G wireless will continue to make use of SS7 and anticipates the migration of the core network infrastructure towards packet- and cell-based technologies.

Transport Protocol Standards
At present, protocols such as ATM an IP are being extended to support mobility. Efforts include work on Wireless ATM (by the ATM Forum) and Mobile IP (by the IETF).

Operating Environments
The elements comprising the network side of access infrastructure are complex. They have full-featured, real-time operating systems, deliver high availability and high performance, and have applications for information manipulation and transformation. Appliances, devices, and terminals are typically small and simple. Also, they must use very little power (to ensure battery life is reasonably long). They depend extensively on DSPs and ASICs to provide functionality for low power and cost. This means they don't have a lot of memory. As a result, they must use simple operating systems and communications protocols. Some operating systems used in wireless devices include Microsoft's Windows CE, Symbian's EPOC and Sun's Java.

Application Development Environments
The quick and cost-effective development of new applications and services also demands that the application development environments for both the devices and the network are simple to use, flexible, scaleable, and open. It is important to keep in mind that all of these technologies, standards, and the resulting infrastructure buildup are simply enabling the development and deployment of wireless services. In the end, it is still up to developers and service providers to develop and provide services.

CONCLUSION
The global wireless network infrastructure is poised for significant growth in the coming years. To get an idea of how much growth we may expect, it may help if we attempted to take in a broad view of a technological history, in which the telecommunications era would reveal itself as following a path very similar to that taken during the development and use of the interstate highway system.

The interstate highway system is designed to move goods and people. The telecommunications infrastructure is designed to move information. The existing 2G wireless infrastructure represents the state of roads in the-mid 1950's. During the end of that decade, the design and construction of the interstate highway system started.

The building of the interstate highway system resembles the evolution of the 3G wireless infrastructure. The first step was to decide the destination of the highway. Then the highway was designed. The number of lanes was specified, the speed limit was decided upon, and the building materials were selected. The details of how the highway was going to be used to transport goods and people, how cities and towns would grow to depend on it and its impact on the economy, could not be clearly imagined early on.

The asphalt and concrete were laid, and the highway was built with a gas station, rest area, or access ramp every so often. It was up to the people following the road builders to imagine and then build upon the possibilities it presented. In conclusion, the current 3G wireless infrastructure is similar to the early interstate highway system - filled with immense possibilities and subject only to the limits of our imaginations.

Jeff Lawrence is president and CEO of Trillium Digital Systems, Inc., a leading provider of communications software solutions for computer and communications equipment manufacturers. Trillium develops, licenses, and supports standards-based communications software solutions for SS7, ATM, ISDN, frame relay, V5, IP, and X.25/X.75 technologies. For more information, visit the company's Web site at www.trillium.com.

aThe ETSI has submitted UMTS to the ITU for incorporation into IMT-2000. The IMT-2000 standards are intended to provide a model and framework that describes how all of the various pieces of the wireless network go together.