WAP enabled phones allow to access the WWW through mobile phones. While this
sounds good, it is currently not that good in reality.
WAP (Wireless Application Protocol) is a protocol similar to HTTP, which is
used to transfer data from a host to cellular phones. As the bandwidth available
is rather limited (usually 9600 bps), compression is an important issue. Also
the connection is much more unreliable than in the Internet and it must also
cope with problems like changing the sender of the information if the user moves
from one cell to another.
While WAP is the equivalent of HTTP, WML (Wireless Markup Language) replaces
HTML for the description of the information, which is sent over WAP. WML is
based on XML, so conventional XML-Browsers should also be able to display WML
pages. The introduction of WML was necessary, as handy suffer from a special
problem (see also below), the small display size.
Because of the different protocols used, cellular phones cannot access a
webpage directly. They need a transformation from HTML to WML, which is done by
the network provider of the phone. As this change of format will usually be of
rather low quality if it is done automatically, it is necessary to provide
important information in native WML format, which will be much more suitable to
the display of the phone.
The problems of WAP phones are numerous:
|Display size: The most significant problem is the display size (e. g.
96x65 pixels). If assuming a text-only interface, this accommodates
approximately 8 lines with 12 characters each in good quality letters. It is
obvious, that not much information can be displayed on such a small screen.
Compare this with an very old-fashioned computer, who has at least 25 lines
of text a 80 characters. Working on them was possible, although a graphical
UI was not used. Because of this small amount of information on display at
once, there are severe consequences: If the information is presented as a
tree, the user has to go to a very high depth, to reach the actual
information. If it is organized like a list, a large number of pages must be
scrolled away. Both modes take a heavy toll with them: The user will
probably often not know, where he actually is and restart from the top.
Moreover, navigation is time-consuming.|
|User interface: Cellular phones have (out of necessity of being small and
lightweight) few and small buttons. This is a severe restriction to the user
interface. While this might be no problem for only passive communication
(the user looks at predefined WML-pages), it is probably next to impossible
to enter a text in a form with a handy. In this way, a very important part
of the WWW, the ability to interact and participate, is cut off. Some might
say, but this won't be needed in the future, we will just use voice-input!
But this will not work in many cases: Suppose you are sitting in a bus: What
will happen if both you and your neighbor try to tell your/his handy, what
to do. The sound-level will rise, and all phones will be confused by the
mass of input they receive. This is because writing a text has no ambient
property, it is a strict one-on-one relationship, while voice is inherently
a one-to-many relationship. Therefore I don't think, that voice-input will
be a really viable solution.|
|Control of content: Currently, your provider for the cellular phone
controls only when and where you communicate, but he cannot control the
content of your communication. In contrast to this, with WAP he also
provides the transformation of the WWW-pages to WML pages or the pages
itself. This is not an optimal solution, if access and content provider
merge to a single instance. However, this problem might disappear over time,
as more and more Pages in the Internet directly provide WML pages. In these
cases, the phone-provider moves back to a simple access provider.|
|What is important enough, to be needed on the phone: Only few information
will be necessary to be accessible through a mobile phone. The information
should be mostly independent from user input and rather small. These
restrictions reduce the amount considerably. Only quickly changing
information, which might be needed either on the spot or only in special
cases (but then immediately) is useful for WML representation. In connection
with this it is necessary to mention, that WML pages are the same for other
WAP-enabled devices, which offer e. g. larger screens and more buttons.|
Usability for mobile work:
Because of the problems mentioned above, I don't think these phones are of
real use for mobile work. They might help in certain cases but generally this technique
will be used by consumers or as a status symbol. Because most work is
interactive, the mainly unidirectional WAP-phones will not be suitable for
carrying it out.
Use for mobile work might be in the area of delivering short information to
mobile workers from a central bureau: The timetable or customers to visit could
be published on private WML-pages, which the employees can look up from wherever
they are. But as those workers will usually carry also a laptop, this is not a
necessity: They could also access them through a conventional webbrowser using
the phone only for the data transfer (but in this case without the help of
compression and reduced information).
Last modified: 13 August, 2002
, by MVS