Location and Presence in Mobile Data Services

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“Mobile technology is expanding our design toolkit beyond the desktop, and those who embrace this technology to enhance the core functions of their products will offer their users a superior experience.”The emergence of a handful of popular mobile data services has changed the way we interact with our phones. Now, several technologies on the immediate horizon are about to change the way we (and our phones) interact with the world. Imagine…

  • You’re about to call your friend, but when you highlight her name in your address book, you see that she’s driving in the city. Since it’s just a social call, you decide to leave her a voicemail instead.
  • Your phone rings while you’re in a crowded movie theater. You automatically know the call is urgent; otherwise, your phone would have automatically silenced itself.
  • You’re wandering through the Paul Klee exhibit at the MOMA, enjoying the audio tour—and enjoying the fact that you didn’t need to borrow a special audio player; a hidden transmitter next to each painting delivers the content to your phone.
  • You’re out and about, and your phone beeps to tell you there’s an open house nearby that meets the requirements you specified through an online real estate service. You don’t have time to tour the house, but you do have time to drive by. You stop in front of the For Sale sign, which contains a transmitter that delivers detailed information about the house to your phone.

All of these scenarios are made possible by location-awareness and presence—two concepts now making their way into mobile devices and promising to enhance everything from social networking to marketing and advertising. Location-awareness enables a device (and the person carrying it) to be geographically located, while presence allows a user to know the status of another user.

Gartner predicts that the number of American businesses and consumers using location-aware computing will skyrocket from 150,000 in 2002 to 42 million in 2005. One reason for such lofty expectations is a 1996 FCC mandate requiring that by December 2005 all mobile carriers be able to locate any subscriber making an emergency 911 call to within an accuracy of 50 to 100 meters.

Even if these projections are overly optimistic, location-awareness and presence will surely change the way people use networked services. We, as designers, need to start thinking about the ways that mobility and location-awareness could enhance each service and application we design. Mobile technology is expanding our design toolkit beyond the desktop, and those who embrace this technology to enhance the core functions of their products will offer their users a superior experience. It’s time to take the Internet out of the office and into the streets.

A Brief History of Mobile Data Services
A mobile data service is any service on a mobile device other than voice calling. It’s worthwhile to present a brief history of mobile data as a backdrop to our discussion of location and presence because of the role these concepts will surely play in the mobile data services of the future. It’s also helpful to provide a sense of the overall market for mobile data.

The first mobile data service of any significance was SMS (Short Message Service) which was originally developed by carriers as a way to send up to 160 bytes of data (including emergency alerts, special promotions, and even software upgrades) from a central point directly to their customers’ handsets. Carriers soon recognized the potential of SMS as an alternative mobile-to-mobile communication protocol, and they began to aggressively market the service toward business professionals–but it didn’t sell.

As it happened, however, limitations in their billing systems made it impossible for carriers to charge their prepaid customers—mostly teenagers and young people—for text messages. As soon as these users discovered they could send text messages for free, the volume of text messages increased quickly enough to threaten the network’s capacity to handle them. (Interestingly, for the youth segment, the usability barriers inherent in mobile message composition became a selling point, since these difficulties meant that the adults in their lives were largely unable and unwilling to use the service.)

If the popularity of prepaid plans—especially among youth—was the key driver for the success of SMS in Europe, then the lack of carrier interoperability was the key roadblock in the United States. US carriers have since resolved this issue, and the text messaging gap has closed quite a bit. The latest statistics show that US mobile users sent 2 billion text messages in April of this year, surpassing the UK for the first time.

After SMS text messaging came a series of SMS-based services, including ringtones, subscription-based information alerts, and SMS-based m-commerce (for example, purchasing items from a vending machine by sending text messages to a special number).

Shortly thereafter, WAP (Wireless Application Protocol) came along, with lots of hype and high expectations, but it was terribly slow and difficult to use. Most users were unwilling to wait several minutes to access a few lines of text displayed on a monochrome screen. In attempting to adapt desktop applications for wireless, carriers and content providers failed to offer any compelling services at all. WAP soon earned the nickname, “Wait And Pay.”

Mobile email and instant messaging had more success, since it was fairly easy to view mobility as an enhancement to these services. Also, the time-based content and flat structure of these services happened to work well on WAP. Mobile instant messaging introduced the concept of mobile presence and pioneered the connection between the desktop and the mobile in a single, continuous user experience. Users who are signed in to a mobile messenger client can communicate just like their buddies on a PC; the core messaging functionality is basically the same on any device.

Other mobile data services of note include mobile games and picture messaging (also known as multimedia messaging or MMS). These have become highly successful, vindicating carriers and analysts who have stood firmly by their belief in the future of mobile data—WAP notwithstanding.

The bottom line is that with an industry as young as mobile data, we can’t always predict what will fly and what will flop. What little data there is suggests that communication-based services are generally more successful than content-based ones.

One thing we know for sure is that users will continually surprise us by reinventing what vendors and designers produce, and it is this unpredictability that makes the mobile design space so exciting. The ubiquity of mobile devices and the willingness of early adopters to experiment means that any flexibility added by designers will be noticed by users.

The Introduction of Location and Presence
Presence management will change the way we use all person-to-person communication media and will affect almost every network service. Knowing a friend’s location and status in advance eliminates the need for a voice call when the only reason for calling is to find out that very information. Additionally, knowing a friend’s mood and activity helps determine which method of communication, if any, is most appropriate. For example, if I’m calling a friend just to chat, it would be useful to know she isn’t busy or in a bad mood. On the other hand, if I’m calling an associate with an urgent business question, I’d like to be able to convey this urgency, to encourage him to answer. More information about all parties in a communication is certain to enhance the communication itself.

Instant messaging introduced us to this concept of “pushed” presence—that is, the ability to see (without specifically requesting) the status of one’s friends. Since its introduction, presence data has become more accurate and more specific. In the beginning, we could merely see whether our buddies were online, offline or away. Later, we could see whether they were active or idle, and for how long. Then came a whole bunch of user-set choices (for example, out to lunch, in a meeting). Now we get real-time feedback, telling us for example when a user is typing. The introduction of location-awareness enables even richer presence data.

When designing presence into applications, designers need to understand the two basic types of presence: system-generated status and user-set status. “Online” and “idle” are examples of system-generated status. Location is another. “Busy,” “bored,” and “invisible” are examples of user-set status. System-generated status is important because it ‘s accurate, reliable, and objective, but it risks revealing things the user does not want to reveal. Therefore, the system, should give the user the ability to suspend, change, or override system-generated status unless there’s a compelling reason not to do so.

In general, systems should not use presence data to set limits that second-guess the user. Rather, systems should use the data to enable the user to make informed choices. For example, even if a user has set her status to “EXTREMELY BUSY,” the system should not prevent someone from calling her.

Designing for presence in general makes for an interesting discussion, but presence has especially profound implications for the design of mobile data services.

The Location Detection Infrastructure
A mix of technologies will make up the location and tracking infrastructure of the future:

  • Cellular triangulation — A mobile phone communicates with the closest cell (cellular antenna or tower). In an urban environment, one’s phone likely to be within range of several other cells as well. Using triangulation, these cells can locate a device indoors or outdoors to within about 120 meters. The precision decreases in rural areas, where a device is often within range of just a single cell. However, in a setting like this, a cell can be modified to detect the angle of transmission-reception in order to locate a device to within a mile or so.
  • Global Positioning System (GPS) — A few manufacturers have begun to sell mobile phones with built-in GPS, which uses a satellite grid to locate a device outdoors to within 3-15 meters.
  • WiFi (Wireless Fidelity) Networks — Several companies have begun to test prototypes of mobile phones outfitted with WiFi (the technology used in home wireless networks), which could be used to locate people indoors or outdoors to within 1-20 meters.
  • Ultrawideband — A few researchers and small companies (as well as the US military) are looking at ultrawideband as a promising location detection technology. It’s extremely accurate (to within centimeters) and requires very little power, but the technology is not very far along in development.

A Design Philosophy for Mobile Data
When thinking about designing the user experience for the next generation of mobile services, it is extremely important to recognize that WAP failed because it attempted to cram desktop computing into tiny devices. So first and foremost, designers need to move away from the WAP legacy and start thinking about mobile devices not as limited desktop PCs, but as versatile, connected, multi-modal devices.

Rather than thinking about the differences between a PC and a mobile phone, think about the difference between someone with a mobile phone and someone without one. Imagine yourself standing on a corner in a bustling neighborhood, and think about what a mobile phone adds to your capabilities (also, imagine standing there and trying to operate a desktop computer, or even a laptop).

Interpolation: On Terminology
As user experience designers, let’s use the term “mobile device” instead of “wireless device” or “mobile phone.”

“Mobile” speaks to the very nature of the device and its advantages over other devices, whereas “wireless” binds it to its relationship with other, older technologies. Mobile tells me what a device is, while wireless tells me what it is not.

“Device” doesn’t denote a particular technology or use, whereas “phone” carries with it many decades of expectations.

That said, “mobile phone” just sounds better in certain contexts, and we shouldn’t expect the mass market to use our preferred designer terminology.

The Multi-Modal User Experience (or, The UX Designer’s Toolkit)
In their latest generation, many mobile devices combine:

  • An audio interface (microphone and speaker)
  • A graphical interface (screen)
  • A physical/tactile interface (keypad)
  • Signal reception and location-detection (cellular, GPS, WiFi, etc.)
  • Connectivity (cellular, Bluetooth, IP)
  • Memory for storage of contacts, messages, photos, etc.
  • A camera
  • A variety of built-in applications (such as a contacts list, calendar, calculator)

This makes for an amazingly rich user experience designer’s toolkit. Right now, as user experience designers, we’re still largely at the mercy of the device manufacturers, but before long we’ll be able to define how these various interfaces and components can be leveraged and combined in a given application.

The Multi-Client User Experience
Beyond this designer’s toolkit, consider the fact that many services will have a user experience that is not confined to a single device. PCs will always have their strengths–a large display, a full QWERTY keyboard and mouse, a fast processor, lots of storage–but we must also recognize the strengths of mobile devices. The most obvious strengths are that they’re mobile and connected. They’re also locatable, and above all, they are designed for communication.

From a user experience design perspective, it’s exciting to think about how a user’s interaction with a particular service can be initiated from one client to another. With PCs, the user typically initiates the interaction and the PC demands her full, undivided attention throughout the process. With mobile devices, however, the application itself often initiates the interaction (for example, by ringing or beeping). This, combined with location-awareness and presence, gives user experience designers an extremely powerful opportunity to deliver the information and functionality best suited to the immediate situation.

The best services will leverage the advantages of each client.

A popular Japanese “item hunt” game called Mogi provides a good illustration of the potential for multi-client location-aware services. In the game, players organized into teams acquire currency by collecting items around the city of Tokyo – the actual city, not a virtual reality simulation of the city. Players using mobile phones are able to see a limited “radar” view of their immediate surroundings. They can see nearby players, and they can collect nearby items. Players using PCs get a macro view of the game. Using various full-city map views and a powerful interface, they can direct the efforts of their team. So mobile players can see less at one time, but they can move about the city, collecting items and engaging each other. PC players, on the other hand, can see much more, but they’re bound to one location, and they can’t collect anything.

Mogi is a good model because it effectively breaks large tasks into parts and assigns these parts to users with the most appropriate devices, leveraging the strengths of each device in a way consistent with how we generally use the devices. The game could easily be re-skinned as a system to dispatch taxis, monitor a truck fleet, manage emergency services or provide commuters with a view of public transit.

The upshot of all this is that it illustrates how designers will need to think about which components in the designer’s toolkit would best enhance the service they’re designing, and which aspects of the user experience are right for which type of client. With such a rich toolkit, mobile applications should offer users as many communication channels, device modes and client interfaces as possible. Applications should also provide enough information to enable users to make highly informed choices and reach their communication goals effectively.

The true promise of presence is that it will enable users to pay less attention to the system and give user experience designers more opportunities to design the interfaces out of the process. Presence will also enable designers to tailor the user experience more than ever before. It’s exciting to imagine a generation of services in which the user experience moves from a computer screen to phone speaker and back, based on the user’s location, situation, and step in a process, and it’s exciting to imagine being able to design for such immediacy and relevance.

Jonathan Grubb designs mobile software applications in hopes of making phones a little more fun and useful. He is currently designing Yahoo!’s new line of downloadable Java applications, which aim to extend Yahoo!’s services beyond the desktop. He was previously with Vodafone in the Bay Area and in Düsseldorf, Germany, where he designed mobile sites and applications for consumer audiences in the U.S., Western Europe, Australia, Africa, and Greece. He is also an artist, showing regularly in San Francisco galleries.

Shawn Smith is a Senior Information Architect at Avenue A | Razorfish. Previously, he managed a User Experience design team at Vodafone, where he was part of the team that created the first prototypes for Vodafone’s mobile data services portal (Vodafone Live!). He also co-managed the development of Vodafone’s first set of mobile interaction design guidelines for developers. Fun fact: He is Shawn Smith VII in the Internet Movie Database.

Mobile: The State of the Art

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“…it will certainly become more and more commonplace to see people transacting with their phones at arm’s length instead of speaking into them.”A few months ago, I was on my way home from the San Francisco Airport in one of those door-to-door shuttle vans. At some point I casually noticed the woman beside me thumbing the keys of her mobile phone. Dialing a number, I assumed—a common enough sight. But then she kept dialing and dialing and dialing.

I had just spent the previous three months in Germany working on a mobile messaging application. While there, I had seen many a teenager and young professional similarly engaged with a “handy” and I had become savvy enough about these things to know that the Germans were sending text messages to each other, whereas my neighbor on the shuttle van was surely just having some kind of problem with her phone. Short Message Service (SMS) is so popular in Europe, they’ve turned the acronym into a verb, but on this side of the Atlantic, our “cell phones” are for talking.

To make a long story short, my professional curiosity got the better of me. I asked, and it turned out she was indeed composing a text message to send to her friend. SMS had apparently hit the States while I was away.

In Europe, non-voice (mostly messaging-related) services account for around 10% of mobile operator revenue. The figure is much higher in Japan, where many mobile phones are full-fledged multimedia devices, featuring color displays, integrated digital cameras, and stereophonic ringtones. The U.S. market is a different story, but things are changing.

The popularity of SMS is not likely to explode here like it did in Europe and Asia. But as more powerful devices and better services become available, it will certainly become more and more commonplace to see people transacting with their phones at arm’s length instead of speaking into them. Mobile devices already represent a significant channel—and they will no doubt become the primary channel—for a number of common human-computer interactions. These interactions often take place during brief pauses in transit, in distracting environments, on devices that are difficult to use, and where mistakes can be expensive. Obviously, a highly usable interface is key, and there is a growing demand for IAs who specialize in mobile.

But try to find a good book on the subject.

The world of mobile phones is a jungle of proprietary technologies with few established standards that, in some ways, resembles the early days of personal computing. I intend in this article to paint a kind of impressionistic landscape of this world; to present a survey of the markets, technologies, devices, and key applications, along with some examples of successes and failures, a glimpse of the near future, and some thoughts on what all of this might mean for IAs.

Key markets

Nowhere has the mobile phone industry burgeoned like it has in Japan. With mobile phones, as with other things electronic, the Japanese have lived up to their reputation for embracing new gadgets as quickly as manufacturers can conceive of them. It remains to be seen whether Japan is a year ahead of the rest of the world or simply a unique market. For the moment, it is safe to assume both are true. The proven success of Japan’s most popular mobile services seems to promise their broader appeal, but the multitude of niche offerings is largely ignored by the rest of the world.

It is worth noting that in their latest generation, Japanese phones are actually a little bit bigger than their predecessors, marking the first reversal of what has been a steady trend toward smallness. The demand for processing power seems to have subjugated the demand for shirt-pocket-sized convenience. Japanese mobile phones double as portable game consoles, music players, and cameras, among other things. They employ an always-on network connection, with data speeds roughly equivalent to dialup modems, so users can download small pictures, sound files, applets, and games cheaply, quickly, and easily.


The Generations of Wireless

1(st) G(eneration): The analog radio cellular phones that first appeared in the 1970s

2G: Digital voice encoding introduced

2.5G: Increased bandwidth; packet routing

3G: Broadband data speeds; global roaming; enhanced multimedia

Europe has the highest average mobile phone penetration rate in the world, and it’s not uncommon for Europeans to own more than one mobile. European mobiles use removable SIM cards – the small chips inside the phones that store the subscribers’ personal information (phone number, contacts, saved text messages, etc.) and identify the subscribers on the network. The European SIM card is universal, meaning it’s easy to remove a SIM from one phone and insert it into another. Therefore, it’s easy for Europeans to upgrade to a new phone or own a whole drawer full of them.

With non-voice services, Europe is following Japan’s example. Operators are scrambling to introduce new color devices and accompanying services to run on their relatively new 2.5G infrastructures. “i-Mode,” the packet-based service for mobile phones offered by Japan’s leader in wireless technology, NTT DoCoMo, has had recent launches in Germany, the Netherlands, and Spain, and European operators are touting Multimedia Messaging Service (MMS) as the next big thing.

The United States
The United States has lagged behind, but the latest service offerings from the biggest American providers suggest the gap is closing—the technology gap, that is. Adoption rates in the U.S. are a different story. The mobile phone penetration rate here is about 45% (compared to about 75% in Europe and 65% in Japan). American consumers have not embraced mobile like their Japanese or European counterparts for a variety of reasons.

U.S. providers, however, are boldly charging forward. AT&T will reportedly offer i-Mode to its customers this year (NTT DoCoMo holds a 15% stake in AT&T wireless), and Sprint recently launched their “PCS Vision” service, which includes color browsing, downloadable stereophonic ringtones, and MMS.

Mobile technologies

This is where things get messy. There is little in the way of consistency at any level. Developers are faced with a huge number of unique client devices running any of the huge number of proprietary operating systems and integrated browsers, supporting any of a handful of development technologies and markup languages, and communicating with the network via any of several digital data transmission standards.

From the bottom up then…

Transmission standards
The selection of transmission technologies has been somewhat regional. The actual mess of acronyms doesn’t warrant a detailed discussion here, but suffice it to say that when it was time to migrate from analog to digital, Europe took a consensus approach. They chose a standard called Global System for Mobile Communication (GSM) to cover the continent. Japan too, allowing politics to intervene, chose a national standard.

In typical fashion, however, the United States decided to let the market drive the decision, resulting here in the deployment of a mishmash of semi-compatible standards. For voice calling, this is not an issue, but transmission of other data across the various standards has been hindered by a number of roadblocks.

Application development technologies and markup languages
With the exception of DoCoMo’s i-Mode, which uses a language called CHTML (Compact HTML—essentially just what it sounds like), WML is the markup language of choice for the wireless web. WML is simply an XML Document Type specific to mobile devices. HDML, the predecessor of WML, is still mentioned occasionally, but for all intents and purposes it is obsolete. The version history of WML can be a little confusing, especially since WML (the language) and WAP (the protocol) are often used interchangeably in the context of version support (e.g., “device A supports WAP/WML version x.x”).

Significantly, XHTML, XSLT, and even Flash have been gaining support (although Flash more slowly), and many new devices will render a familiar range of image formats. This means that from a technical standpoint, developing for mobile phones will become more and more like any other web development, so the burden will be on IAs to design channel-appropriate interfaces.

One other mobile development technology bears mentioning: Java. Sun created a slimmed-down version of its language and called it J2ME. It is designed to accommodate the limited computing power of mobile devices and allow them to run small, self-contained applications. Computing power isn’t always the only limitation to be accommodated, however. Bandwidth, as well, is an issue for applications that are to be delivered for over-the-air downloading.

Operating systems and browsers
The mobile world is in the midst of its own browser wars, and most often a device’s built-in browser is tightly integrated with its operating system. The biggest players are Nokia/Symbian, Ericsson and Openwave, although Microsoft has recently begun to move into the wireless space.

Nokia, the leading handset manufacturer, has recently begun to peddle a productized version of its software to other device manufacturers. Alternatively, Openwave, whose main business is software, has seen their Phone.com browser installed in a wide range of handsets. That, however, has far from guaranteed any kind of consistency. Openwave’s software has been deeply customized for certain manufacturers, and there are even different customizations of the software for different handsets by the same manufacturer.

This means the same markup is rendered differently on different devices. It also means the interaction between the hardware, the software, and the remote application—the physical mapping of the phone’s keys to the application’s functions—cannot easily be predicted or specified.

The range of devices on the market continues to expand, with new devices being introduced much more rapidly than old devices are being retired. The best way to make some sense of it all is to take a zoological approach, to impose a classification system on the multitude of species.

There are two useful facets of such a system: degree of mobility and amount of computing power. Focusing on mobile phones, I divide these into two classes. The more common, and therefore more familiar, of these is the set of monochrome data-capable phones. The other class is the set of more powerful phones with large, full-color displays. My chosen differentiators in this case are rendering capability and navigation method (as expressions of computing power).

This classification system obviously has its limitations. Some monochrome phones, for example, support Java, and some don’t. Some color-capable phones don’t support four-way scrolling. And there are always anomalous devices that defy easy classification altogether, like the Handspring Treo 180—a powerful “Smartphone” that happens to have a large monochrome screen.

Key applications

At the moment, a common perception is that mobile computing is little more than a poor imitation of desktop computing. Critics wonder why anyone who has access to a computer would bother to agonize their way though an m-commerce (ecommerce on a mobile device) transaction. The simple answer is: they wouldn’t.

The mobile applications most likely to succeed will be those that take advantage of their mobile-ness. I have mentioned i-Mode as an example of an application that has succeeded, but it’s useful to focus on the broader categories that this example and others represent.

By far, the most successful non-voice application in the mobile world is SMS. Remarkably, it was originally conceived not as a consumer product but as a way for mobile service providers to send data—anything from promotional messages to technology upgrades and patches—to their subscribers. These subscribers quickly embraced it as an inexpensive way to send short messages (originally 160 bytes maximum, at about 15 to 25 cents each) from mobile to mobile. According to the GSM Foundation, Europeans send as many as a billion text messages every day (compared to 12 million in the United States).

More recently, various enhanced messaging services are gaining popularity, including different mobile implementations of popular Instant Messaging services like Yahoo! Messenger and AOL Instant Messenger, and Multimedia Messaging services.

Outside Japan, browsing content via the wireless Web has arguably flopped. “WAP is crap” goes the saying. However, the introduction of new color devices and the rollout of higher-speed networks have brought renewed hope for the future of mobile browsing in general. Most people believe that the browsing applications most likely to succeed are those that provide targeted, on-demand information (e.g., sports scores, stock quotes, and weather reports) quickly and easily, and obvious and immediate utility (e.g., travel and event booking, auction bidding, and gambling).

Research has shown that people who use their phones for non-voice applications often do so as a way of killing time while commuting, for example, or waiting in line. Games provide an ideal distraction. Some amazingly simple games have been a hit with mobile phone users, demonstrating that people who expect their PCs to immerse them in minutely-rendered 3D worlds are nonetheless willing to spend 15 minutes a day playing “Snake” while they ride the bus.

Games can be delivered in several ways. They can ship with the phone as built-in applications; they can reside on the network to be played during active sessions; or they can be delivered as complete applications via one-time over-the-air downloads.

Personal information management (PIM)
Most phones on the market today include a suite of built-in PIM applications such as an address book and calendar. Some phones also include email and synchronization support for Outlook or other PC clients, and WAP (Wireless Application Protocol) portals like Yahoo! and MSN provide mobile support for their popular Webmail clients, as well as POP support. Mobile PIM applications show special promise for enterprises looking to support a mobile workforce, and PIM applications are primary candidates for full, frequent multichannel use.

Location awareness
Location awareness is an application enhancement, not an application category. The architecture of the mobile telecom environment makes subscribers locatable geographically, though not with GPS-like precision. Operators are adding location features to messaging services and games, as well as to more utilitarian applications like restaurant and club finders. Obviously, privacy protection is a key concern for services that incorporate locatability.

The Role of the IA

All the basic tenets of our profession certainly apply to the discipline of mobile user interface design, but these underlie a number of unique considerations.

Mobile usage patterns are distinctly different from what we associate with the desktop PC. Mobile sessions often occur in public places, during brief pauses. Unless the user is idly browsing or playing a game to pass the time, she is probably seeking a piece of very specific information or trying to accomplish a single very specific task. Time is often—literally—money, so there is effectively no margin of error. If the user navigates down the wrong path or downloads the wrong file, she pays for the mistake.

IAs obviously need to understand the contexts within which a given application will be used, to understand the physical environments, the motives and circumstances, and the target devices. There are many questions that apply especially to mobiles: Will the user be moving or standing still? Will he be operating the device with one hand or two? What are the most likely distractions or obstacles? What if the connection is dropped?

It is important to remember that in many cases, users’ attention will be divided. They will interact with an application while walking down a flight of stairs or while half listening for their flight number to be called.

Because of the variety of device capabilities currently in use, IAs must frequently decide whether to exploit the advantages of a given device or to design something more generic to accommodate a broader range of devices. Screen sizes on mobile phones range from the tiny to the miniscule, so IAs must abandon notions of point-and-click in favor of click-and-flow.

Since users are presented with so little information at any given point, it becomes especially important for them to know where they are within the system (and where they were, and where they can go). Wireless data speeds are usually equivalent to a dialup connection or slower, and devices have very little storage capacity or processing power. Finally, users don’t have the luxury of familiar input devices like a mouse or alphabetical keyboard, and many users are only roughly familiar with the behavioral quirks of their chosen clients.

Most mobile phones currently in use support only one-color graphics. This severely limits visual branding opportunities, and while it may be possible to an extent to brand interaction design, it is more important to stick to familiar user interface conventions and metaphors as much as possible. Users are likely to encounter more than enough uncertainty without our help. We don’t need to create more uncertainty in the pursuit of distinctiveness or innovation.

We declare all the time that less is more. With mobile phones, one would think perhaps we don’t have a choice. Even so, the maxim applies. The simplest interfaces are the most successful. Wizards, for example, generally work better than forms because of their one-step-at-a-time simplicity. A login process requiring a username and password, then, should be a three-step, three-screen process (1. username 2. password 3. submit). On the other hand, perhaps such extreme simplification would be maddening to power users. There’s only one way to find out…

Test. Conducting usability tests on mobile applications is difficult. There are few software or hardware tools designed for testing mobile phones, and there are few documented guidelines or best practices. But that’s also part of what makes it exciting. As with all frontiers, we are required to imagine, to innovate. I worked quite a bit with a firm that used an awkward-looking setup involving a miniature spy camera and duct tape, but it gave us exactly what we needed.

Any of the points above could of course warrant at least an article all its own. I look forward to the opportunity to discuss in much greater detail some of the particulars of mobile user interface design.Acronym Soup

ARPU Average Revenue Per User
CDMA Code Division Multiple Access (a digital voice encoding format)
CDMA-2000 The broadband CDMA standard developed by Quaalcom and Lucent for 3G
GPRS General Packet Radio Service (a packet-switching protocol designed to improve data speeds on GSM networks)
GSM Global System for Mobile (the most common worldwide mobile communications standard)
HDML Handheld Device Markup Language
J2ME Java 2, Micro Edition
LBS Location Based Services
MMS Multimedia Messaging Service (mobile-to-mobile transmission of images, video, sound)
OTA Over-the-air
PCS Personal Communications Services
SIM Subscriber Identity Module (a sometimes removable microchip that stores a subscriber’s personal data and the information necessary to identify the subscriber on the mobile network)
SMS Short Message Service
T9 Text input on nine keys (a text-input helper application that employs a database of commonly-used words)
UMTS Universal Mobile Telecommunications System (a 3G transmission standard)
WAP Wireless Application Protocol
W-CDMA Wideband CDMA (a 3G standard)
WML Wireless Markup Language

Standards organizations

Developer sites

Other resources

Shawn Smith has worked as an IA and user experience designer since 1996. Currently he develops applications and UI standards for Vodafone, the world’s largest mobile operating company.