The purpose of this chapter is to briefly introduce all of the background technologies which are related with our research. Many related works and some real products of the market will also be presented and described in this chapter. The mentioned technologies include GSM cellular phones, the Internet solutions for mobile phones (WAP, GPRS, 3G, i-Mode…, etc.), the PDA and desktop PC, MExE, information retrieval, and mobile agents.
The related works and real products include AGORA services, Info-On-Demand, AvantGo, iSMS, semi-automatic wrapper generator, …, etc. Some references about mobile agent runtime environment technologies will also be described in this chapter.
3.1 Background and terminologies
This section will survey and explain many related internetworking devices, terminologies, technologies of the market, and then describe the possibility for operating mobile agent by mobile devices. Some important technologies and researches will be explained more detail in the following chapters.
3.1.1 Mobile cellular phone
According to the survey of the International Telecommunication Union (ITU) in 2003, the penetration ratio of mobile phone in Taiwan is 106.15%, which is the 1st all over the world.
Needless to say, the applications of mobile phones are more and more popular and fantasy.
Now, connecting the mobile phone into the Internet, and utilizing the great amount information and applications on the Internet is the great ambition for most mobile phone service providers. The research [44] estimates the following statistics about the mobile phone users all over the world:
z 540 million roaming cells were made in February 2000
z 750 million cells were predicted in June, July and Augusts 2000
2004
z 8 billion short messages were sent in May 2000 z 10 billion short messages were sent in December 2000
z One billion short messages were sent per month in Europe alone in 2001
z GSM (Global System for Mobile Communication) grew at 80 percent in 1999:
PC grew at 22 percent
z More GSM terminals will be connected to the Internet than PCs by 2005 z Wireless devices will access 30 percent of all Internet traffic by 2005
According to the previous listed information, it can conclude that utilizing mobile devices to surf the Internet is more and more important and popular activities on the Internet. If there is an easy and cheap way for mobile users with mobile phones to interact to the Internet, the mobile user's vision will be dramatically expanded. However, before the 3G era coming, use the small screen size, very limited computing power, short battery duration, and the expensive and low bandwidth network mobile phones to connect to the Internet and retrieve the information from it is very difficult. All the solutions on the desktop are no more applicable on the mobile phones. For instance, in PC, if we want to search something on the Internet, we only have to connect to the network, and then install any WWW browser. Consequently, we may view any documents and information available on the Internet via the browser.
However, the same works can't be easily applied into mobile phones. It is impossible for most mobile cellular phones to install any full function WWW browser, and the very limited size display is not suitable for reading the common WWW pages on the Internet.
Furthermore, most current mobile phones of the market have no any ability to expand their function. So we only have to use the built-in components of the mobile phones to operate the remote mobile agents and applications. The well known built-in messaging functions are SMS (Short Message Service)/EMS (Enhanced Message Service) /MMS (Multimedia Message Service), WAP (Wireless Application Protocol), or E-MAIL. We have to choose one of the messaging functions as the media for operating to the mobile agents on the remote hosts. We will describe the related technologies of WAP, SMS/EMS/MMS, in later of this section.
First of all, the type of technologies for the networking connection between GSM mobile
phones and the Internet are shown as follows:
Wireless MODEM: Wireless MODEM is a traditional and the most common equipment for GSM mobile phone to connect to the Internet.
Actually, the function of wireless MODEM is almost the same as the wired MODEM of the traditional wired home network. Nowadays, almost current modern mobile phones are equipped the wireless MODEM. As long as the GSM mobile phone service provider provides the data transmission service, the mobile users can treat the wireless MODEM of the mobile phones just as the normal PC MODEM.
That is, when the mobile phone has connected to the computer by transmission cable, IrDA, or even BlueTooth, the operating system of computer will recognize the wireless MODEM as a normal general MODEM. The user may setup the MODEM and dial up to the Internet Service Provider. Just as a normal wired MODEM does. Thus, if the user has enabled the data transmission functionality to his GSM service provider, he can connect his computer via his mobile phone as well as the wired network connection. Of course, those mobile phones with embedded WML (Wireless Markup Language) browser can direct connect to WAP sites on the Internet, but the bad news is that the network speed now in Taiwan is only 9600 bps, it is very limit for most Internet application services. Moreover, the connection cost is very expensive in Taiwan too.
GPRS (General Packet Radio Service): Work on GPRS started in 1994, and a standardization of the GPRS had been frozen by ETSI (European Telecommunications Standard Institute) in 1999. It is a packet-based data bearer service for GSM networks, which provides both standards with a way to handle higher-data speeds. It will make mobile data faster, cheaper and user-friendlier than wireless MODEM solution. By introducing packet switching and Internet Protocol (IP) to mobile networks, GPRS gives mobile user faster data speeds, and particularly suits bursting the Internet and intranet traffic. Connection setup is almost instantaneous, and users can have always-on connectivity to the
mobile Internet, enjoying high-speed delivery of e-mails with large file attachment, Web surfing, and access to corporate LANs. This technology is treated as the temporary phase before the arriving of 3G mobile phones. In the past, there were more than 6.4 million GPRS users worldwide by end 2002, and it was approximately 150 GPRS networks operational in 58 countries. Also, there were more than 50 million GRPS terminal devices delivered worldwide.[52] These numbers are all increasing in a very great pace currently.
3G (3rd