Mobile web for under-privileged in developing countries
Introduction
Like any other part of the world, majority of people in developing countries need access to information that matter for their daily life and livelihood. Access to information is critical to reduce digital divide, create jobs, and stay ahead in the competitive world. Cost of computers is quite high; infrastructure for running computers with stable electricity is not widely available; also, availability of high bandwidth data is not widespread at many places of developing countries. These constraints make it difficult for common people to access Web or the Internet using computers. One of the major options for under-privileged people in developing countries therefore is to access information through mobile web.
Following its commercial launch in 1992, GSM (Global System for Mobile Communications) became the most popular technology in mobile communications. It took 12 years for GSM to reach the first billion subscribers; second billion was achieved in just 2.5 years and out of this second billion 82% subscribers are from the emerging markets like China, India, Africa, and Latin America (World Bank Report). Majority of these subscribers are prepaid subscribers (from 75% to 97% with respect to different countries).
In 1991 WWW (World Wide Web) was invented, which became the major vehicle for information exchange. Soon in advanced economies, GSM and Internet converged into GPRS (General Packet Radio Service) and 3G to offer Web over cellular networks (Fig. 1). However, in many developing countries, cellular networks are still using GSM technology. In some developing countries where GPRS networks are available, due to challenges in real time IP (Internet Protocol) billing, wireless Internet or data over TCP/IP is generally not available to prepaid subscribers. Moreover, majority of phones sold in developing countries are mainly budget phones (GSM Association). These phones support only voice and SMS (Short Message Service). This has been acknowledged by W3C (World Wide Consortium) as a real challenge for mobile web – W3C therefore proposed SMS as the transport bearer (SMS-data) for mobile web for under-privileged in developing nations (W3C International Workshop).
In advance economies like the US or Europe, mobile web may mean browsing Internet or accessing actionable information through an Internet browser using a mobile device over wireless TCP/IP. Definition of mobile web in developing countries that contributes to 60% of the total mobile phones population could be accessing the same actionable information on the Web through mobile phone – but not necessarily over TCP/IP or an Internet browser. According to W3C definition (W3C International Workshop), mobile web for developing nation is “not at all to connect people to the Web but to provide services (health, banking, government services, education, business) which would improve the life of the most under-privileged population”.
Researches to study the traffic behaviour on GPRS so far include three basic Internet applications, viz., FTP (File Transfer Protocol), email (Electronic mail), and WWW (World Wide Web). In these applications traffic is asymmetric; small amount of data is sent from client to the server as request (in order of tens of bytes), and a large amount of data sometime in kilobytes or megabytes are received from the server. In case of actionable information through online transaction, the client to server traffic could be in order of tens of bytes; the response from server to the client will also be of similar order. Actionable information are these information that will influence the course of the action. Examples could be when is the next train expected, or what is the price of wheat in the nearest market, or job alert for a daily-waged person.
SMS can be used as SMS point-to-point and SMS-data. In case of SMS point-to-point a user sends a short message to another user. In case of SMS-data (SMS as transport bearer), one endpoint will be a mobile phone whereas the other endpoint will be an application or a service in the Web that is connected through SMS gateway (Fig. 2). An SMS gateway is connected to the home SMSC (SMS Centre) of a mobile operator and accessed through a short-code like 333, 10816 etc. (see Section 4, for detail explanation). This short-code is the SDSI (SMS Data Service Identifier) and configured as the port address on the SMSC (Fig. 2) where the SMS gateway is connected. In the USA there is a service called Common Short Code Administration (Common Short Code Administration), where the availability of a short-code can be checked and reserved. Reservation of a short-code does not imply that the code will be available. Through separate agencies, this common short-code needs to be activated within each operator’s network and there are cases where due to commercial reasons an operator may not activate this code. Such facilities are not generally available in rest of the world; therefore, in other countries subscribers of different operators access the same service through different SDSI.
The message exchange between an MS (Mobile Station or the mobile phone) and an SME (Short Message Entity – an SMS Application Server or an SMS Gateway) is illustrated in figure 03.40/4 in GSM standards 03.40 (GSM 03.40). GSM originally defined specification for SMSC and SME communication through GSM 03.39 (GSM 03.39); however, this standard has been withdrawn and made SMS to SME interfaces out of GSM scope (GSM 03.40). This imposes a major constraint on SMS-data – it is home network centric and does not interoperate. A subscriber of mobile network “A” can make a voice call to any subscriber in another network. A subscriber of mobile network “A” can send an SMS message to any mobile phone from any network. A subscriber of ISP (Internet Service Provider) network “A”, can access any data service hosted on another ISP. However, a subscriber from mobile network “A” cannot access an SMS-based data service that is offered by some other network (i.e., not home network of the mobile operator).
SMS gateway (technically called SME in GSM standards) converts an SMS PDU (Protocol Data Unit) into an Internet PDU where it connects to a Web site through HTTP URL (Hyper Text Transport Protocol Unified Resource Locator). In addition to converting the PDU, the gateway also functions like a proxy. However, there is a major difference between a proxy for Internet in an enterprise or ISP and a proxy in mobile operator. For an Internet, one proxy handles all traffic from a subnet and basically does network address translation. The filtering process for an Internet proxy is driven by security and privacy policies of the enterprise facilitated through blacklisted sites. In case of an ISP, the proxy does only the address translation. In case of SMS-data however, this is different. There are multiple gateways in an operator – one gateway for one content provider – the proxy here is logically designed to work only for content provider’s URLs. These services are generally called Value Added Services (VAS). The flow is – when a user sends a request to a short-code, the SMS is routed by the SMSC (SMC Controller or SMS Centre) to the port with ID as the short-code where a SMS gateway is configured; the SMS gateway does a filtering based on a whitelist (GSM 03.40). Unlike the normal Web, where a user can access any service in the Internet, a subscriber of a mobile operator cannot access a service unless the operator carries it. Also, if a social organization or an NGO (Non Government Organization) wants to offer a service to people, they cannot do so without entering a commercial agreement with the operator. Moreover, if that service needs to be offered to a larger cross section, all operators need to be tied up with – this is an impossible task and a major roadblock for mobile web.
As discussed above, it is clear that Web-based actionable services over cellular network at emerging market in developing countries need an alternative bearer. According to the authors and W3C (W3C International Workshop), SMS-data is one of the strongest contenders for above scenarios. However, with respect to above discussions, SMS-data is not interoperable, stateful and needs a web-based architecture. To the best of authors’ knowledge, this paper carries for first time the combination of an architecture referred as USRS (Ubiquitous/Universal SMS Routing Service) technologies that solve interoperability challenges as identified by W3C in W3C International Workshop and stateful as well as secure mobile web, to provide Web-based services over the SMS-data transport in an interoperable and stateful manner. Furthermore, the authors have carried out a comparative study of GPRS and SMS-data based mobile web performance by simulation. It has been observed that, SMS-data based actionable web-services shows considerable performance improvement over GPRS.
The paper has been structured as following. Section 2 defines actionable information that forms the basis for wireless web for under-privileged. Section 3 illustrates the challenges in TCP/IP and actionable information over GPRS network. Section 4 presents the proposed architectures to support Web over cellular network by SMS-data. Section 5 presents simulation results and discussion for actionable information in SMS and TCP/IP. We conclude this paper in Section 6.
Section snippets
Web browsing versus actionable information
By definition, Web is a procedure for accessing services deployed on the Internet using HTTP (Hyper Text Transport Protocol). In Web, users use the browser to access the Web that works in client server mode for facilities like FTP (File Transfer Protocol), Internet email, and WWW (World Wide Web). Actionable information on the other hand relates to lifestyle specific contents that could be business, exchange, banking, or e-commerce related service. Actionable information service may also be
Challenges with actionable information over GPRS (using TCP/IP)
Actionable information systems are interactive in nature where the user requests for an actionable information and receives the result through stateful dialogues in a series of complex processing at the server end. These dialogues between the user and the services can be work, or business, or lifestyle related, e.g., enquiring the end-of-day sales figure, e-trading, tele-banking etc. MVC systems simplify and abstracts such complex business processes distributed over multiple systems by
Integration of proposed architectures to support Web by SMS-data
SMS has certain other advantages – it being auto-configurable, it supports seamless mobility from one network to another. Also, SMS works in a vehicular state. However, available technologies for accessing applications over SMS have two major constraints that prohibit SMS to be used as a transport bearer. These are:
- 1.
SMS-data is operator proprietary and does not interoperate. We proposed USRS (Ubiquitous SMS Routing Service) technology to overcome this challenge (the detail architecture with
Results and discussion: actionable information over GPRS and SMS
This section presents simulation results of GPRS and SMS-data for supporting mobile web for actionable information. There is a perception that SMS is not reliable and SMS suffers from quality of service problems. In this section we present simulation results for SMS as a transport bearer and compare it against TCP/IP. We looked at the work done by Benko et al. (2004) where authors have studies 12,587,056 TCP packets over multiple live networks in Europe and Asia. We also looked at (Chakravorty
Conclusion
In this paper we presented the architecture and technology suitable for mobile web for the under-privileged. Mobile web will bridge the gap between have and have-nots and will help eradicate digital divide. We presented how SMS can be used as a transport bearer for mobile web. We presented routing algorithm for SMS-data in mobile number portability scenario. We have also evaluated the SMS-data performance to show how it performs against TCP/IP. SMS works well at low signal strength. SMS offers
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