May 1999

The Impact Of CTI On Wireless Communications

BY BROUGH TURNER

Wireless communications now grows faster than wireline communications, and it will continue to do so indefinitely. There are two reasons. The first is Moore's law. It happens that this law, which calls for continuous, exponential growth in the performance of electronics circuits, helps wireless more than wireline communications. It costs money to install cable, and Moore's law does not apply to the cable, let alone to its installation cost. True, many wireless solutions are more expensive today, but long-term cost trends favor wireless.

The second reason is convenience. The convenience of not being tethered - indeed, of not even having to plug in a cable - is significant for telecommunications, and even for appliances that seldom need to move.

RELEVANCE OF CTI
But how is the growth of wireless helped by CTI? CTI hastens the transition of telecommunications from proprietary to mass market information technology, to platforms that present a richer and most flexible software development environment. Today, software is the dominant cost in developing and deploying new products and services. Yet it is possible to reduce this cost by relying on mass market information technology, that is, on PCs and the Internet.

When PC technology can meet cost and reliability targets, it is the best basis for new telecommunications products and services. And the range of applications for which mass market computing technology applies is expanding. One driver is CompactPCI, which is helping to build robust systems. Another is embedded PC technology, which is being deployed in cost-sensitive applications.

CTI, with its open telecommunications components and approaches, has been widely adopted for voice mail, voice response, and other applications in the corporate enterprise. And it has made substantial inroads in enhanced services in the public telephone network. Now, with the explosive growth of the Internet, the promise of voice over IP (VoIP) and the emergence of CompactPCI, the pressures on traditional telecommunications equipment vendors are mounting. As a result, we're beginning to see open telecommunications technology carrying live voice traffic in the telecommunications infrastructure as well. Wireless is now fertile ground for open telecommunications approaches.

IN-BUILDING WIRELESS SYSTEMS
There are several reasons for the growth of in-building and campus-scale wireless systems. There are real applications where mobility is key, in warehouse operations, for example. In addition, there are applications that offer such convenience that users may find them irresistible. For example, an application may let you use your cellular or PCS handset while in your office. This application would be especially attractive if it allowed your handset to function as part of your office PBX, without the charges that would apply if you were to use the handset when you were away from your office.

There is even a significant incentive for your cellular service provider to subsidize such in-building systems - it reduces "churn," that is, turnover in their customer base. When you have an in-building system that works with a particular wide area mobile phone service, there's a strong incentive to stay with that mobile service provider. If, for example, your office has an in-building wireless system that works with phones from AT&T Wireless, you are not likely to buy PCS service from Sprint. If you did, you would need two handsets, one for calls outside your building, and one for calls while in the office.

Why Now?
Some wireless service providers began introducing compatible in-building wireless systems a few years ago. These solutions involve the installation of low-power base stations in a corporate office building. The base stations use the same licensed RF frequencies as the wide area portion of their wireless network. Wires are run from the in-building base stations back to a special-purpose controller that is interfaced to the PBX. Until recently, the equipment for these in-building wireless systems has been completely custom designed. But open telecommunications technology is entering the picture.

First, integrating these in-building wireless systems with the existing PBXs requires exactly the same kinds of hardware and software interfaces as are needed for voice mail - basic CTI. Second, it's more efficient to transport the compressed speech frames of a digital wireless system over a high-speed, packet-based media such as Ethernet than over ISDN or proprietary digital telephony - and virtually all office buildings are wired for Ethernet. So Ethernet makes sense for transporting speech between base stations and the PBX room. Indeed, new base station systems are emerging today, from Nokia, Ericsson and others, that provide the same over-the-air interface to the wireless phones, but use 100 Base-T for in-building connections. These base stations simply take the coded speech off the air interface, wrap it in IP packets, and ship those packets over the Ethernet LAN anywhere within the corporate enterprise.

The gateway used to connect an in-building wireless system to the legacy telephone network, either the PBX and/or public telephone trunks, is a natural for open telecommunications technology. Integration with the PBX is a business already dominated by CTI component solutions. The job of transcoding from the wireless speech compression used with the chosen handsets to standard 64 Kbps speech used in the traditional telephone network is a task for low-latency DSP functions - the same kind of function performed by DSPs in a VoIP gateway. The rest of this system is made up of software that can run on the CPU within the gateway box or on a Windows NT or UNIX server elsewhere on the LAN - all open telecommunications components.

Impact Of Using IP In The LAN
Integrating in-building wireless with VoIP systems becomes a natural. In fact, one of the speech coders supported in Microsoft's NetMeeting product is the same GSM speech coder used in most of the digital cellular networks outside of North America and in some North American PCS systems. If your in-building wireless system is GSM-based, then you are potentially able to communicate between a NetMeeting client and a wireless handset with no transcoding.

Of course, there are call control issues. The VoIP market is focused on H.323 call control, while wireless systems use more arcane wireless standards. However, software to adapt differing call control protocols is another strong point for the CTI industry. With voice over IP growing and IP-based telephone systems emerging from companies like Selsius (now part of Cisco), NBX (now part of 3Com), and others, the outlines of a new form of business telephony are becoming visible.

With IP backhaul, wireless handset-to-handset connections are made without transcoding, unlike traditional wireless systems, which convert the voice data to 64 Kbps for switching and then recode it for connection to the second handset. Eliminating these conversions, whether going from handset-to-handset in a building or handset-to-handset between buildings, avoids transcoding steps which can degrade the voice quality, and the same intranet can connect VoIP gateways and individual wireless handsets between separate corporate sites. Indeed, IP back haul for in-building wireless systems has extra advantages for corporations with multiple sites. Most large corporations have a private corporate IP intranet or are able to acquire a Virtual Private Network (VPN), a piece of the public Internet provided by an Internet backbone provider, with a service level that is good enough for voice connectivity between sites. Voice over IP between buildings saves money.

Wireless IP LANS, Too?
While voice is the bulk of the in-building wireless business, there are data-related wireless applications that can't be ignored. With an in-building wireless data network, you can connect your laptop computer to the corporate network via a wireless link. Then you can move from your office to a conference room with your laptop constantly connected to the network - maybe not at 10 or 100 Mbps, but at least at 1 to 2 Mbps.

Right now data is a small piece of the in-building wireless business, but it is IP-based, which leads to the next logical question: When will voice over IP over wireless data networks emerge? While that prospect may seem fairly remote right now (since most in-building wireless voice systems use traditional cellular or PCS air interfaces), there is already at least one company providing voice-over-IP over wireless data LANs - Symbol Technologies. Symbol Technologies got into the wireless data LAN business to support mobile barcode readers in supermarkets and warehouses. Their VoIP over wireless Ethernet solution is on the market today.

CTI FOR PUBLIC WIRELESS NETWORKS
So mass-market computer technology is helping to bring cost-effective wireless solutions into the enterprise. But what about public networks? Specifically, what about the wide area public telephone network, including cellular and PCS? What about wireless in the local loop?

Wide Area Wireless Service
Can we expect CTI-based wireless solutions? There are examples here as well, but until recently they have all been from second- and third-tier vendors. However, with the advent of CompactPCI, this is changing. Over the past year, the buzz among CompactPCI chassis vendors has been about RFQs from major wireless infrastructure equipment vendors, who appear to be designing their next-generation wireless systems on CompactPCI. It's early days, but the time-to-market advantages of open systems are compelling.

Meanwhile, the combination of CompactPCI for robust systems and open telecommunications platforms for flexibility means that PC technology is finding its way into myriad niches, such as protocol gateways (SS7 to V5.2, V5.2 to V5.1, and others too esoteric to name). But, beyond CompactPCI, won't the other forces at work in the enterprise apply just as well to wide area wireless service? IP back haul is appearing in in-building systems in large part because the wiring - Ethernet - is already in place. The wide area world is mostly wired with traditional telephone trunks, but the Internet is growing very rapidly.

The first signs of IP in the wide area will be the widespread use of IP to carry the signaling messages that today are transported by SS7. Since IP is so pervasive, it costs less and offers more flexibility than is ever possible from a specialty technology like SS7. Standards for SS7-IP gateways are in development within the Internet Engineering Task Force (IETF), but pre-standard deployments are already happening.

Prospects For The Wireless Local Loop
More dramatic are the possibilities for IP and mass market computers in wireless local loop (WLL) systems for developing countries. Why vocode the speech to 64 kbps and switch it with an expensive central office switch? Instead, connect the wireless base stations to an IP cloud. Replace the central office switch with a cluster of computer servers running the call processing software and IP routers routing the actual voice data streams through the IP cloud.

Of course, this approach requires million lines of software before a highly available server cluster can replace today's central office switch. But, much of the special software for wireless systems already resides in directories called the home location register (HLR) and visitor location register (VLR), and these directories are running on, or can easily be ported to, mass market computers. And much of the rest of the needed voice-over-IP infrastructure is being developed today for deployment in large landline telecommunications systems.

OPEN TELECOMMUNICATIONS AND WIRELESS
Traditional telecommunications carriers, both wireline and wireless, are under pressure from the growth of Internet and the threat of VoIP. Computer telephony components are already accelerating the growth of in-building wireless systems. All the signs are there. Open telecommunications is penetrating the wireless market and fostering the growth of wireless systems and services.

Brough Turner is senior vice president of technology at Natural MicroSystems, a leading provider of hardware and software technologies for developers of high-value telecommunications solutions. For more information, call Natural MicroSystems at 508-620-9300 or visit the company's Web site at www.nmss.com. E-mail to the author (rbt@nmss.com) is also welcome.