February 15, 2003

As emerging technologies are making mobile computing as easy as working from our office, many aspects of the wireless internet are constantly changing. Several different protocols are attempting to standardize the means through which server-based software applications communicate with mobile phones and PDAs to carry out administrative and service-related tasks. The two main protocols competing for the large market of 3rd generation appliances are WAP and I-mode.

In this discussion we compare the two protocols, outlining their differences as well as their respective advantages and disadvantages.

I-mode is a wireless technology that was launched in February 1999 by a Japanese company NTT DoCoMo that enables users to access internet services via their wireless phones. I-mode (I stands for information) is based on packet data transmission technology. This means that I-mode is always online, and therefore users are charged only for how much information they retrieve, not how many minutes they are using it for.

I-mode can be used to receive email, exchange photographs, receive news and stock quotes, shop online, receive weather forecasts, balance checking/fund transfers from your bank account, retrieval of restaurant/town information, play online games and access music files online.

Instant access to websites compatible with I-mode can be achieved at touch of a button. Let’s say if this service was offered in Pakistan, every subscriber would get an email id, such as <@docomo.ne.pk>. This would work as your cellular phone number. This would enable you to send and receive mail of up to 250 full-size characters for about Rs4 to send mail, and approximately Rs2 to receive mail. Your mobile phone number is initially set as your email address. Of course, amidst all this excitement of being able to access the internet on the go, one tend to forget that you can also make and receive phone calls on an I-mode enabled phone.

This I-mode technology, when first offered in Japan, obtained over six million subscribers only fourteen months later. At present, there are more than 30 million subscribers in Japan. The user needs an I-mode enabled device, such as a Smart Phone in order to use the service. The transmission of the information utilizes the Code Division Multiple Access (CDMA) protocol. Since the transfer rates for data is still significantly lower than the average modem, I-mode is insufficient for videos and large images; it is mainly appropriate for email and simple graphics.

Components required for I-mode services are:

— I-mode cellular phone: a phone capable of voice and packet transmission along with a browser installed

— Packet network: an I-mode server for communication purpose.

— C-HTML: compact mark up language is used for writing contents. It works in the same way as HTML work for web pages to display data.

How it works

I-mode uses a PDC-P (Personal Digital Cellular-Packet) method of data transmission over the existing PDC network used for ordinary voice traffic. This is a packet switched network that is well suited for wireless communication. In a packet switched network, data is broken into small units called packets and routed over the net. This mode of transmission where communication is broken into packets allows the same data path to be shared among many users in the network.

The markup language that I-mode uses is cHTML or compact HTML which is a subset of HTML and very similar to it. It is designed for devices with slower connecting speed. One main difference between the two languages is that some of the more resource intensive areas of the code such as tables and frames have been bypassed in cHTML. This is understandably to reduce the download time to mobile devices. So an I-mode enabled website utilizes pages written in cHTML and being similar to HTML, it is easy for web designers to create. This cHTML content needs to pass through a cHTML gateway before users can access it on their mobile phones using the I-mode browser.

When an I-mode compatible wireless device makes a wireless request, the gateway translates this to the server and back from the server to the wireless device. Thus, users can stay online throughout and yet not be charged for the time spent online. Rather, they only pay for the amount of data that they retrieve. This is in contrast to the circuit switched network such as the regular voice telephone network where the communication path is dedicated to the callers thus blocking that path to other users for that period of time.

Differences

As the Japanese giant NTT DoCoMo recently expanded their services into the European market we may witness a convergence of the two global standards in Mobile Internet technology, Wireless Application Protocol (WAP) and I-mode. They are essentially similar technologies allowing the user to access web-based information with transactional capabilities from a mobile phone. However, there are some major differences. The first basic difference between WAP and I-mode is in the level of graphics supported by the two and this is where I-mode scores over WAP. Although WAP supports some amount of graphics, it doesn’t match the capabilities of I-mode. This was made evident in the latest tie-up between NTT DoCoMo and SEGA to provide online gaming through I-mode phones.

The reason for I-mode’s superiority over WAP is due to difference in the network structure. WAP uses circuit switched network while I-mode uses packet switched data network, which is more suited to transferring data than circuit switched networks. Also, the packet-based network contributes to the “always on” nature of the I-mode service where the user is always logged on to the internet. This is another aspect, which goes in favour of I-mode because the users only pays for the data that they retrieve and not for the time that they consume on the net.

But, then again as much as this goes in favour of I-mode, this could also be the hindrance in expanding I-mode services to other parts of the world. Japan uses the PDC-P network, which is really not a world standard while other parts of the world, such as Asia and Europe have circuit switched networks in place. This means, even if I-mode were to expand its services it would still have to depend on the existing network in that country so the major drawback of circuit switched networks still remains.

Another difference is in the markup languages the two use, I-mode uses c-HTML which is a subset of HTML while WAP uses WML which is a subset of XML. Although c-HTML is similar to HTML and easier for web designers to use, XML is considered to be the internet language of the future as HTML has limited capabilities. Just like the browsers, Internet Explorer or Netscape, used on a PC seek an HTML page, the micro-browser in an I-mode phone is software designed to run on a hand held device and used to access a cHTML page. As of now, the rate at which data is being transmitted is 9.6kbps but with DoCoMo going all out to develop the W-CDMA or Wideband-Code Division Multiple Access technology, a third generation mobile communication system, speeds of 384kbps or more could be in the offing. The W-CDMA allows high-speed data transmission of video and large-volume data.

Although I-mode services are restricted to Japan, expectations are high that their services will be further expanded to Europe, the UK, Asia and the US. It remains to be seen whether NTT is successful in making inroads into other parts of the world.

The writer is a young scholar of MCS at SZABIST, Karachi

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