Wireless
Messaging
Interoperability Matrix
by Bern Elliot, eCommunications
Corp.,
and Andrew M. Seybold, Andy Seybold Computing
(Originally published in Messaging Magazine, May/June 1999)
About EMA's Wireless Messaging Group
This article presents a model that outlines the five core components required to implement a complete end-to-end wireless messaging solution. These components are presented in a form that roughly parallels the flow of wireless messaging information between enterprise servers and wireless devices.
This introduction provides a high level overview of each component. These components are then discussed in more detail. Note that specific standards and formats need not be discussed in order to understand these core components. Regardless of how specific issues are solved for each of the components, the basic model remains the same.
The components in the wireless messaging model shown in Figure 1 are:
Servers
A wide range of enterprise servers, including e-mail systems, unified messaging systems,
voice mail systems, and communication servers may be configured to interact with wireless
devices. Matching the right server application to the device is simply a matter of work
productivity. For example, some individuals may find it productive to use an intelligent
e-mail filtering system, which would forward specific e-mail messages from the desktop to
the user’s wireless device. Other individuals may find value in receiving
event-triggered wireless alerts, such as a stock alert or a critical security alarm alert.
Still other individuals may want to receive a text alert indicating an urgent voicemail
awaits. These examples are already happening today on a wide scale. In each of these
examples, the goal is the same: release the employee from the desktop, thereby enabling
greater mobility and productivity.
Enterprise Firewall
When a message leaves an Enterprise server it must first traverse the Enterprise firewall
and cross the Internet in a secure manner. There are typically two secure ways to reach an
Internet-based server or a wireless service. The first is via a dialed up telephone line.
While using IP over a dialed up line on the PSTN (Public Switched Telephone Network) is
generally considered quite secure, there are additional mechanisms that can be implemented
to enhance the point-to-point security. The second method is to use one of the Internet
Mail security protocols such as S/MIME. These approaches typically encrypt the data
exchanged between the two communicating servers, thus making the message content secure.
In some cases, this encryption is performed at the firewall, while at other times it is
performed at the server.
Internet-Based Wireless Services
Once a message leaves the Enterprise, it can travel directly to the appropriate airtime
carrier via Internet, private network or dial-up connection. This is the simplest and most
direct route to a carrier. Internet-based services, however, increasingly are being used
to extend the reach and flexibility of the wireless solution. A wireless network
operations center (WNOC), for example, can help solve three critical wireless messaging
problems:
This "packaged" model provides your enterprise access to a range of wireless solutions.
Wireless Network
Wireless carriers provide the communications infrastructure needed to reach mobile
devices, and thus mobile users. Each carrier operates its own licensed coverage areas. In
many cases, there are agreements between carriers to allow "roaming" or movement
of devices between coverage areas. Carriers typically support only one protocol and in a
specific frequency range. For these reasons, coverage is a factor in the wireless
messaging model of today.
Wireless Device/Form Factor
The wireless messaging device is the component most visible to the end user. These devices
come in a wide range of sizes and weights (form factor) and also support different
features and protocols. Some devices are as small as a pager and carry only text and
numeric information. A pager is quite suitable for receiving e-mail information. Wireless
phones are also capable of sending and receiving messaging using a technology known as SMS
(Short Message Service). Other devices similar in size may be capable of storing only
voice messages. Larger wireless messaging devices may be extensions of palmtop PDAs or
wireless modems.
The Server
Typical enterprise servers include e-mail systems, unified messaging systems, voice mail
systems, database systems, and communication servers. It is here where many wireless
messaging actions are initiated. For instance, an individual may wish to have all e-mail
subjects and the first 100 characters of the text forwarded to their wireless device.
Messages received for their account by the e-mail server are appropriately formatted and
forwarded to the indicated address of the wireless device. Another example is a
communication server that monitors critical events such as stock movement or security
alarms. In these cases, end-users customize thresholds which trigger event or alert-based
messaging. Critical to alert messaging is the ability to set profiles and the reliability
of delivery.
The wireless server can be owned and operated either by the enterprise or by a service provider. In-house servers allow more control over actions such as integration, log-on, and security. This greater control, however, can also increase the administrative and operational burdens of the company support staff.
In some cases, servers interact with external services. For example:
When interaction is required, administrators should be aware of the external system’s format requirements.
Most wireless server applications base their activities on a user profile. Each user profile defines and controls the type of information that is received on their wireless device. In the case of e-mail, this may include only messages of high priority or from specific people. With alerts, the profile may define stock price/volume levels and trigger messages according to these thresholds. For voice messages, each user typically defines the call forwarding number and/or alert e-mail address.
The Firewall
Perhaps the piece of the matrix puzzle that has been hardest to put into place are methods
of penetrating "firewalls" designed to protect corporate data from outside
access (Ref. Figure 2). These firewalls are installed by
corporations and since they prevent outsiders from accessing corporate data, they also
keep authorized users out of the corporate messaging centers.
Several companies, including Research-in-Motion, InfoWave and Wireless Knowledge have developed secure means of providing access between wireless networks and the corporate LAN. Microsoft, Lotus and others are also working on secure methods to permit corporate LANs to be connected to wireless data networks so that messaging services can be offered the mobile work force and provide a high level of security for the corporations.
This is the hardest part of the matrix to put into place at the moment. On-going work will continue to make secure access to corporate servers possible. Until we have solved this problem on a broad scale the market for wireless messaging will remain smaller than the demand for these products.
Internet-Based Services
The base function of the Internet is to provide transport service between the enterprise
and the service provider servers. Value added wireless services, however, increasingly are
being provided in the form of Internet-based applications.
One such entity which uses Internet-based applications is the wireless network operations center (WNOC). As shown in Figure 3, this type of center solves three critical problems:
A WNOC allows your enterprise to access a range of wireless solutions from a single source.
The Wireless Carrier
Wireless Carriers, also known as wireless network operators, that are located in the
United States and Canada can be divided into two basic classifications: Voice and Data
capable networks and Data-only networks. The term Voice and Data capable means that the
wireless operators have configured their networks to handle both voice and data.
The Voice and Data carriers make use of one of three different digital standards: CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), or GSM (Global System for Mobile Communications). All of these technologies are presently deployed in North America. Figure 4A provides information on Voice and Data Wireless Carriers in North America. TDMA and CDMA technologies are used on both the existing cellular channels (800 MHz) and in the new PCS spectrum (1.9 Ghz). GSM has only been deployed in the PCS spectrum.
At present, the GSM networks are the only networks that support voice, short messaging, and dial-up data. The dial-up data rate over GSM is 9.6 Kbps. CDMA networks today offer voice and short messaging and by the end of this year many of them will also be offering dial-up data connections at a data rate of 14.4 Kbps. The TDMA systems, most notably, those operated by AT&T, SBC, and Bell South, support both voice and short messaging, but for the foreseeable future will not be offering any form of dial-up or packet data capabilities.
In addition, Nextel offers voice, short messaging and now dial-up data at a rate of 9.6 Kbps using a Motorola technology referred to as iDEN. iDEN is a digital technology based upon the TDMA standard, but proprietary to Motorola.
A new wireless voice messaging service uses Motorola’s InFLEXion protocol, which allows for the transmission and storage of voice messages. This protocol uses a combination of simulcast transmission, as found in one-way paging networks, and frequency reuse, as used by cellular radio networks. Through system technology improvements and digital voice compression techniques, tremendous gains in spectrum efficiency and capacity have been made to make voice messaging applications possible.
Data-Only Networks
There are a number of data only networks operating in North America. As shown in Figure 4B, in the United States there are three networks: American
Mobile, based upon a digital technology call DataTac developed by Motorola; Bell South
Wireless Data using a digital technology developed by Ericsson called Mobitex; and
Cellular Digital Packet Data or CDPD (sometimes called wireless IP) which has been
deployed by cellular carriers including AT&T, Ameritech, GTE, and Bell Atlantic/NYNEX.
Each of these networks has different data characteristics and throughput. American Mobile’s systems provides excellent in-building coverage, is nationwide, and today covers approximately 90% of the U.S. business population. A sister network run by Bell Mobility in Canada covers that country.
The BellSouth Wireless Data network operates at a data rate of 8 Kbps and it too, is designed to provide in building coverage. This network is also nationwide and covers in excess of 90% of the US business population. There is a sister network operated in Canada operated by CanTel.
CDPD (Cellular Digital Packet Data) is provided by various cellular network providers and today covers approximately 50% of the US business population. There is also a CDPD network running in Canada. The data rate of the network is 19.2 Kbps.
Metricom runs the Richochet network in three major metro areas in the United States: San Francisco Bay Area, Seattle, and Washington, DC. This network, while appearing to a user as a dial-up network with data speeds up to 33 Kbps is also based upon packet radio technology. It was not designed as a mobile network but rather as a portable network, the present network does not support use while in motion.
Other networks which should also be considered for mobile e-mail include the two-way paging networks operated by SkyTel, PageNet, and PageMart. These networks cover varying degrees of the United States and provide e-mail services to and from two-way paging devices.
All of these carriers are ready and willing to provide data services to the mobile worker and, depending upon the carrier and the technology, can provide short messaging to full e-mail capabilities.
The Wireless Device
Devices capable of wireless messaging are available today in many shapes and sizes, with
many more device emerging over the next year. Devices range from "smart-phones"
equipped with a microbrowser to computer devices with built-in wireless modem. Generally
these devices can be placed into four broad categories:
In addition, many standard wireless phones can be plugged into a standard notebook or handheld computer and act as a wireless modem if the network they are on support data. Palm Corporation has just announced a version of their Palm product that includes a built-in wireless modem. We expect to see numerous other products enter the market based upon the Windows CE operating system and others.
Computer and wireless device manufactures have all indicated their continued interest in building new and different end-user devices. The task for the end-user will be to determine which device, running across which of the available networks, is best suited for their messaging requirements.
Conclusion
Wireless messaging is not new. Over the years a multitude of both public and private
standards and models have been defined. However, a major change is propelling wireless
applications into the mainstream of Enterprise communications. The key factor underlying
this change is the shift towards TCP/IP and Internet based standards in the wireless
industry. As this shift occurs, applications are becoming increasingly independent of
underlying "airlink" protocols. This is often coupled with better carrier
coverage and improved device reception. Together, these factors have radically altered the
face of wireless messaging.
Today, enterprise messaging managers should include IP-based standards in their wireless decision process, but the most critical requirement will remain—whether the application delivers the required functionality. Simply looking for wireless IP networking is insufficient for most applications. This is in large part because TCP/IP-based interaction, as it is today, does not operate well over the variable speeds and interrupted communication sessions common to wireless links. To solve this problem, Enterprise managers should ensure that they have end-to-end application continuity for the specific applications that they wish to deliver to their users. The matrix outlined in this article should assist in this process. MM
About EMA's Wireless Messaging Group
The Wireless Messaging Group is focused on promoting wireless messaging technologies and solutions into the mainstream of enterprise messaging.
EMA WMG Charter: "The EMA Wireless Messaging Group (WMG) promotes the current and emerging role of wireless technologies as it applies electronic messaging. It facilitates the development and interoperability of wireless messaging by promoting discussion, education and critical review."
Participation: Participation in the EMA WMG is open to any EMA company. For more information on the EMA see www.ema.org. A WMG list server has been established to facilitate the distribution of information in this group: wmg-l@ema.org. To subscribe to this list server, send a message with the message body containing "subscribe WMG-L" to address "requests@ema.org" (no quotations).
General Goals: The WMG will focus on tasks that work towards the goals outlined below. The group will decide how to best achieve these objectives.
1. Educate users, vendors, and service providers about wireless messaging.
- Arrange speaking tracks at committee meetings, EMA events and other forums.
- Implement a demonstration showcase at EMA events and other forums.
- Plan and run tutorials that assist in advancing Wireless Messaging as a mainstream Enterprise solution.
2. Provide a forum for discussion of wireless messaging solutions.
- Liase with other EMA groups, with other industry groups, and with standards groups to promote understanding and consensus.
- Provide a method for exchange of needs and requirements between users, vendors, and service providers.
WMG Co-Chairs:
Bern Elliot, eCommunications Corp.
215-985-2292. elliot@acm.orgPhil McRoberts, Research in Motion
519-888-7465 X543. pmcroberts@rim.net
EMA Contact:
Lauren Haywood
Vice President, Member Services and Administration
Electronic Messaging Association