Packet Switching Types: ATM, Frame Relay, TCP/IP, X.25

Transmission: SONET T-Carrier

Services: [3G] [4G] [Bluetooth] [I-Mode] [WAP] [Wireless and packet switching]

From the Agilent web site: http://www.agilent.com (external link):

UMTS: Farther along the road to the wireless Internet

The first wave of third-generation (3G) wireless services is due to be deployed in Japan during the summer of 2001. For the rest of the world, evolutionary technologies such as General Packet Radio Service (GRPS) are filling the gap between second- and third-generation services (see the GPRS article, "A stepping stone to the wireless Internet" (external link, was here, probably dead now: http://www.agilent.com/Feature/English/archive/C015.html)). It will take time to achieve the visionary 3G future featuring mobile phones as multifunction, multimedia devices that deliver the Internet anytime, anywhere.

But even as the mobile phone industry works hard to roll out gap-filling GPRS solutions, it's keeping an eye on the real goal: Universal Mobile Telecommunications Service (UMTS). Conceptually, UMTS represents a grand promise to deliver all kinds of multimedia content anywhere, anytime, and to any device. No one can predict the precise form of future mobile applications, services, and devices. However, everyone agrees that the communication networks carrying UMTS will need to be vastly expanded and improved versions of today's infrastructure. System creators know which key parts of present and future mobile networks will need to be strengthened to increase the flexibility -- and simplify the future enhancement -- of the whole system.

Looking behind the scenes

Concepts abound for amazing new mobile devices that combine the capabilities of mobile phones, PDAs, digital cameras and more. However, little attention has been paid to the other crucial element of this two-way radio system: the cellular base station. In a box that's somewhere between the size of a filing cabinet and a refrigerator, the base transceiver station (BTS) provides the critical connection between mobile devices and the wired network that connects them to the rest of the world.

First and foremost, the BTS must be both an extraordinarily good multichannel radio and a powerful, high-capacity interface to the phone network. To enhance the BTS for the transition to UMTS, designers will need to substantially improve both its radio and its network functions.

On the radio side, new designs will improve BTS power efficiency and signal quality, reducing interference with other radios. Digital technologies -- powerful microprocessors and signal-processing techniques -- promise to radically simplify future enhancements by allowing the functions of the radio to be changed in the programming instructions that control the microchips. Such a "software-defined radio" would eliminate the need to change the costly two-way radio hardware for the transition to a UMTS system.

Improving BTS network functionality is equally critical to the future success of UMTS. The BTS of tomorrow will need to handle tremendous capacity -- a two-way torrent of information that will be a mix of voice, data, video and other media. For optimal performance, the BTS will need to handle the different media types in different ways. For example, wireless data services require high speed, error-free transmission, but are tolerant of the ever-changing time delays (variable latency) inherent in mobile, wireless communications; that is, whenever the distance between a moving two-way radio and the nearest (cellular) antenna is constantly changing. On the other hand, voice services tolerate only short, consistent time delays (low latency) but are somewhat more tolerant of transmission errors; that is, when people are talking, the human brain can fill in the lost pieces of a sentence (transmission errors), but inconsistent time lags, even short ones, cause people to constantly interrupt each other, effectively ruining their conversation.

Beefing up the rest of the network

The challenges of improving network functionality in base stations are extended and amplified when trying to improve functionality in the rest of the network. Meeting latency and capacity requirements is increasingly difficult, especially in an environment of mixed media types. Third-generation networks must be able to adapt themselves to the changing traffic they'll carry, optimizing their performance to meet the needs of both users and system operators.

One important network operation is getting serious attention and goes by a colorful name: Backhaul is the process of routing the combined data traffic of a base station to a mobile switching center, where it is then connected to the public telephone network. Improving backhaul capacity is a critical task to support UMTS services, and it's being addressed with technologies as diverse as copper wire, fiber optic cable, point-to-point microwave systems, and free-space optical (laser) techniques. Tomorrow's networks must be flexible enough to operate effectively with such a mix of backhaul technologies and capacities.

Coping with a mixed world of 2G and 3G

A final challenge to system flexibility arises from the fact that many of the world's regions won't complete the migration to 3G or UMTS any time soon, nor will they do so at the same time. Second-generation and enhanced second-generation wireless systems like GPRS will probably be dominant for the next several years, and probably won't be phased out for at least a few years after that. In many locations, the second- and third-generation networks will operate together, or in adjacent areas. Once again, technologies such as the software-defined radio may be the most effective way to meet this challenge so that radios will evolve as the system changes, without the need to constantly upgrade hardware.

Wireless solutions from Agilent Technologies

Helping create and support this evolving, heterogeneous environment is a huge test-and-measurement challenge. Fortunately, Agilent solutions are available for virtually every part of the transition to UMTS, including networks, base stations and user terminals. Agilent products cover optical, wired and wireless network technologies, from instruments that analyze individual components to system products such as Agilent acceSS7 that monitor and analyze entire networks.

For more information

Several parts of the Agilent Web site present information relevant to the creation of present and future communication networks. The best general starting point is the Communications Solutions section, which provides links to additional information for people working with wireless networks, optical networks, the core network, and more.

Feature Stories Archive

The Feature Stories Archive is a collection of the general-interest articles that have appeared on the Agilent homepage. These stories cover a wide range of topics in our four business areas: communications, electronics, healthcare and life sciences. Please visit the Archive index page (external link, now dead) to scan the headlines and summaries, and to link to the past stories.

[Editor's note. Don't forget to download and read Agilent's excellent report on 3G:]

3GPP & cdma2000 Basics by Agilent Technologies (external link below, may now be dead)

http://www.agilent.com/cm/wireless/pdf/3G-Seminar2001_02.pdf (32 pages, 1.5 megs)

Packet Switching Types: ATM, Frame Relay, TCP/IP, X.25

Transmission: SONET T-Carrier

Services: [3G] [4G] [Bluetooth] [I-Mode] [WAP] [Wireless and packet switching]