Pervasive Learning with Wireless and the P-Reference Implementation

Transcription

1 Pervasive Learning with Wireless and the P-Reference Implementation Abstract In this report, Pervasive learning is proposed and one of the key technologies, wireless networks, is surveyed. Two currently commercially available wireless data networks are detailed and evaluated for P-learning. To cater the large population of Palm OS PDA users, a P-learning service, P-Reference, is proposed and detailed. The first version of P-Ref, Princeton P-Ref 1.0, is implemented for Palm VII(x). Users can download P-Ref 1.0 from our project web site and install it into their Palm VII(x) to access 6 different on-line dictionaries wirelessly. 1. Introduction E-learning has been successful both commercially and educationally. As the Internet, the enabling technology for e-learning, are getting pervasive, it s a natural to think about the Pervasive learning, P-learning, which enables users to access instructional information anytime and hopefully anywhere. What s the virtue of pervasive learning? Learning itself is pervasive and continuous. People take in input from the outside world every second they are sane. They process such information every second they are not obsessed. Normally they run into questions from time to time. How do people get questions answered? They can experiment/observe or refer to some knowledge base. The later one is of our interest. People ask other people for answers. People get questions answered while attending class, reading books, watching TV programs, and most recently, browsing the Internet. Another question is, where do people do so? Classroom, library, office, computer cluster and etc. In one word, people do not get questions answered real timely and in field in most cases. The virtue of P-learning is that it is to enable people get as many questions as possible answered real timely and in field. Wireless network is one of the choices to enable P-learning. More exactly, it is one of the important enabling technologies for learning to become pervasive. Like the Internet changed people s experience with computers, we believe wireless technologies will change people s experience with the Internet. In section 2, we surveyed and analyzed currently available/promising wireless data networks which is going to enable the concept of P-learning in our belief. As an example, we proposed a service, P-Reference, for wireless handheld users in section 3. The P-Ref is implemented for Palm VII(x) and users can download it from our project web site. Section 4 offers an overview of future works and our conclusion for P-learning.

2 2.Wireless Resources and Evaluation There are basically two types of wireless data network now available, i.e., Wireless LAN and cellular wireless data network, which is based on the wireless voice communication networks. For pervasive learning, we will have to rely on them at least for some time. Therefore, it s important for us to first examine the currently available wireless resources and see what kind of services for pervasive learning they can support. The difference between WLAN and PalmNet is highlighted by Table 2.1. We ll examine them for bandwidth, latency, availability and price etc, which we are concerned with. Palm Ricochet Bandwith (kbps) <=28.8 (in the following several years) Download 128 Upload 64 Latency Relative ly high Relative ly low Price for unlimited access about $50/month about $75/month Availability Widely available Around major metro areas, expanding now Handheld device Palm OS PDAs and other handhelds Any devices installed with a proper modem Applications Not communication intensive such as query Almost all the applications Internet supports 2.1 Wireless LAN Table 2.1 Difference between PalmNet and Ricochet WLAN A lot of communication companies are ambitiously planning to deploy the wireless LAN across US as they did in the past for the telephone lines and cellular systems for mobile phones. Ricochet is one of the first that really have done something. Table 2.2 shows several Wireless LAN(WLAN) technologies currently under development. Technology Rated Typical TCP Bandwidth Throughput IBM Infrared 1 Mbps Kbps Lucent WaveLAN 2 Mbps 50 Kbps -1.5 Mbps Metricom Ricochet 100 Kbps* Kbps Hybrid wireless cable 10 Mbps Mbps Table 2.2 According to Hari Balakrishnan with the Daedalus Group in UC Berkeley *Metricom now claims the bandwidth is 128kbps for downloading and 64kpbs for uploading

3 Architecture According to Metricom, Ricochet is a high-speed, high-bandwidth wireless network covering major metropolitan areas in the USA that delivers high-speed mobile access and remote access. The overall architecture of Ricochet network is showed in Figure 2.1 Mo Internet and Corporate Networks 900 MHz Poletop Radio 2.3 GHz 2.4 GHz High-speed dedicated wired connections Wired Access Point Network Interface Figure 2.1 Ricochet Network Architecture Users access the networks through the radio devices installed on the top of street light poles. Ricochet uses both unlicensed and licensed spectrum. Unlicensed, regulated 900 MHz bands are used to communicate to end-user devices. The radio power is less than 1 watt, which is of no harm to health. They are excellent for in-building coverage. The 2.4 GHz band for higher speeds is used in the rest of the network Availability Today, Ricochet is available at 128 kbps in the following markets: Atlanta, Baltimore, Dallas/Ft Worth, Denver, Detroit, Houston, Los Angeles, Minneapolis-St Paul, New York City, Philadelphia, Phoenix, San Diego, and the San Francisco Bay Area. These areas join the Washington, D.C. and Seattle 28.8 kbps service areas, allowing Ricochet users to take advantage of the freedom of wireless mobility on a nationwide basis. Ricochet 128 kbps service is also planned for the following markets: Albany, Albuquerque, Austin, Boston, Buffalo, Charlotte, Chicago, Cincinnati, Cleveland, Colorado Springs, Columbus, Indianapolis, Kansas City, Las Vegas, Memphis, Miami, Milwaukee, Omaha, Orlando, Pittsburgh, Portland, Providence, Raleigh /Durham, Richmond /Petersburg, Rochester, Sacramento, Salt Lake City, Santa Fe, Seattle, St Louis, Tulsa, Virginia Beach and Washington, D.C. Figure 2.2 shows the national coverage.

4 Figure 2.2 Ricochet Network Coverage Map According to Metricom claims that Ricochet is available for customers when they travel within any covered metro area in motion up to 70 MPH. Price Ricochet technology is not compatible with the IEEE standard for Wireless LAN. Users must purchase special modems to access the Ricochet WLAN. Table 2.3 shows the service price and modem price for different Ricochet subscriptions. Ricochet Reseller PartnersService price (monthly) Modem price GS $49.95 $74.95 GS $99 $74.95 $825(annually) $79.95 GS $99 Merlin $299 AirCard $299 $59.95 GS $100 $79.95 $74.95 Merlin $ Merlin w/pcmcia jacket for the ipaq Pocket PC $ Table 2.3 According to Client Hardware Any handheld devices (including Palm OS PDAs) and PCs can access the WLAN after modem installation and service subscription.

5 2.2 Palm Net Before the pervasive Wireless LAN becomes real, Palm tried hard to augment its handheld devices with the wireless capability. It chose the cellular data networks of the BellSouth, which were originally for wireless telephony. The bandwidth for such networks is at most 28.8kpbs at the time being. In most cases, it is between 8kbps and 19.2 kbps. 3G wireless network is now evolving and promising a data rate of 386kbps. However, 3G wireless network is expected to take years to become true in US. Before the high data rate wireless LAN become pervasive, Palm.com s choice of cellular network will be desirable for some years. Architecture Figure 2.3 shows the overall network architecture for PalmNet. Web Clipping Proxy server Figure 2.3 PalmNet Architecture, according to The BellSouth Wireless Data Network is evolved from the cellular network for mobile telephony. Due to the limited bandwidth and the low display power of Palm PDAs, Palm.com developed the technology called web clipping, which is basically a reduced version of web browsing and html standard. A key component of making the system work is the Palm Computing Web Clipping Proxy server that resides in 3Com Corporation s data center. The Web Clipping Proxy server is responsible for converting the standard Internet protocols and content from a web page into a form that s tuned for transmission across a wireless network and for display on a small device. The Web Clipping Proxy server uses standard Internet and security protocols (TCP, HTTP, and SSL) to HTML servers to ensure compatibility. However, on the wireless side, it must adjust everything to support extremely low bandwidth and latency. Note that all data on the left side of the Web Clipping Proxy server in the illustration is compressed to ensure maximum efficiency in the wireless environment.

6 Availability According Palm.Net, The Palm.Net Wireless Communication Service works in over 260 of the most populated areas in the U.S. The same rates apply everywhere, and there are no roaming charges. Figure 2.4 shows the national map for the coverage. Figure 2.4 PalmNet Coverage Map According to Price The Palm.Net Service Plan (Up to April 21, 2001) is showed in Table 2.4. BASIC PLAN EXPANDED PLAN UNLIMITED VOLUME PLAN Monthly service fee $9.99 $24.99 $44.99 Kilobytes included in monthly service fee 50KB* 150KB** Unlimited 30 messages 90 messages Sample monthly 20 stock quotes 60 stock quotes 10 sports scores 30 sports scores usage*** 10 traffic reports 30 traffic reports N/A 10 weather rpts 30 weather rpts Each additional kilobyte $.20 $.20 N/A One-time set-up fee $9.99 $9.99 $9.99 *Approx. 50 screen views **Approx. 450 screen views ***Individual usage in each category may vary Table 2.4 PalmNet Service Plan According to

7 Client Hardware The web clipping technology is supported only by the Palm OS. Only Palm OS PDAs can use the PalmNet. However, More than 70% of PDA users both worldwide and US nationally are using Palm OS as illustrated in Figure 2.5. This will justify any service proposed ad hoc for Palm OS PDA users. 2.3 Evaluation Worldwide 70% US 79% Figure 2.5 Palm OS PDAs Market share According to Palm.com Internet experience is very much relied on the bandwidth of the connection between the users and the Internet. Table 2.5 shows the research by Aberdeen Group Bandwidth Requirements for Personal and Enterprise Applications Bandwidth Text Web Browsing Rich Messaging File-and-Print Enterprise Apps 14.4 kbps X 28.8 kbps X X 64 kbps X X X X 128 kbps X X X X X Table 2.5 Research by Aberdeen Group, Nov. 2000

8 Table 2.4 shows the different services supported by different network bandwidths. Obviously, it is only marginally possible for PalmNet to support web browsing, let alone multimedia/interactive e-learning services. On the other hand, Ricochet WLAN will be suitable for any current wired e-learning services as long as the client devices have the computation and display power, which is true for most laptop and pocket PCs. We can expect PDAs in the near future will be capable enough to support all the wired on-line e-learning services. Therefore, once WLAN becomes pervasive, the on-line e-learning will naturally become Pervasive learning with proper handheld devices. The problem at this time being is what service we can provide for Palm OS PDA users with limited bandwidth and computation/display power. 3. Pervasive Reference and Implementation Palm Net has wider coverage and Palm OS PDAs have the lion s share for the PDA market. This motivates us to propose a Pervasive Learning service for the Palm OS PDA users. 3.1 E-Dictionaries to P-Dictionaries Electronic Dictionaries have been integrated into many PDAs and are very popular. Users can look up the dictionary whenever they have their PDAs with them. On the other hand, many dictionary publishers have made their dictionaries available on line, e.g., Merriam-Webster ( Compared with the e-dictionaries stored locally in the PDAs, the Internet has many advantages. First, materials on the Internet are maintained and updated by the content provider. Second, there is almost no storage limit for the Internet but the PalmVII still has to do everything within its less than 8M ROM. Last but not the least, the Internet is far more versatile than any e-dictionaries. PDAs are being augmented the ability to access the Internet. For Palm OS PDAs, Palm proposed the web clipping technology, which will accommodate the html web pages with Palm PDAs small screen and limited wireless internet access bandwidth. Now, Palm users can search the Yahoo! database and find people using the Yahoo! PeopleSearch web clipping program. They can find the area code information through Com s database using the web clipping program. Such applications are quite successful today. Therefore, why not enable Palm users to access all sorts of on-line dictionaries wirelessly? 3.2 Pervasive Reference Things are not limited to dictionaries. There are a lot of people on the go and keep on learning like professionals and students. They refer to a lot of handbooks, manuals and tutorials for the definition of terms, brief explanation of concepts and instructions for certain operations etc. Why not enable Palm users to access such kind of instructional information wirelessly? We define Pervasive Reference as something people can use to access certain brief and usually one-timeuse instructional information like what we aforementioned. Dictionaries, manuals, tutorials and handbooks are very suitable for wireless access from handheld devices. First, every time the user only needs one or two items from the database instead of the whole. However, since what the user needs is very diversified and not well predictable, it will not be wise/possible to store all the stuffs in the limited storage of the handheld. Moreover, using pervasive reference, the user can choose to save locally certain information got wirelessly if she finds it may be useful for her frequently. Second, such referred information such as definitions, brief explanations and

9 operational instructions are usually short and do not demand high bandwidth or large display. They are good for the Palm Net users. Industries have been providing similar services. For example, Atomica Corporation provides knowledge retrieval and delivery services ( Its services are available to Palm users through its web clipping program which is downloadable from Atomica and Palm s homepages. One thing worth mentioning is that although we proposed this service for Palm Net users, it is readily applicable for other handheld device users who have access to Internet through wireless LANs. 3.3 System Architecture The system architecture for the Pervasive Reference is showed as follows. Handheld using WLAN WLAN CGI Contracted Databases Handheld using PalmNet PalmNet CGI Princeton Pervasive Reference Servers/Databases Figure 3.1 Handheld devices, WLAN and PalmNet have been detailed in the previous section. The databases could be proprietary or contracted with other content providers. The web pages are processed by CGI (Common Gateway Interface) scripts, which transform them into desired forms. For users using different network and handheld devices, the CGI is different. For example, when a Palm user is requesting data, features not supported by Palm OS such as flash animation and video are got rid of and new features like advertising banners are added. The CGI scripts will run on the Princeton Pervasive Reference servers. 3.4 Context Augmented Search The searching engine and database organization nowadays are based on matching, i.e., matching the user input with the database. Advanced searching may add some constraints like different ways of keyword combinations and where the keyword appears. However, as people know, as there are a lot of ways to use a same word (almost in any language), once we find the word in the database, the context where the word shows up is most important to determine which meaning is applied here. Unfortunately, the context information is most ignored by nowadays searching engines. For example, if a kid runs into the word operation when she is reading an article on the grass in the sun. If she uses the and Palm to look up the meaning wirelessly, the result will be

10 1 : performance of a practical work or of something involving the practical application of principles or processes 2 a : an exertion of power or influence <the operation of a drug> b : the quality or state of being functional or operative <the plant is now in operation> c : a method or manner of functioning <a machine of very simple operation> 3 : EFFICACY, POTENCY -- archaic except in legal usage 4 : a procedure carried out on a living body usually with instruments especially for the repair of damage or the restoration of health 5 : any of various mathematical or logical processes (as addition) of deriving one entity from others according to a rule 6 a : a usually military action, mission, or maneuver including its planning and execution b plural : the office on the flight line of an airfield where pilots file clearance for flights and where flying from the field is controlled c plural : the agency of an organization charged with carrying on the principal planning and operating functions of a headquarters and its subordinate units 7 : a business transaction especially when speculative 8 : a single step performed by a computer in the execution of a program Only one of the three will answer the kid s question. However, the other 7 waste the precious display, power and communication resources. Moreover, different. We proposed to augment the search engine with the context information. The user can specify the scenario in which she runs into the problem. If she likes, she can also specify the field the word is from by guessing. For example, if she runs into operation while reading one paragraph about things in a hospital, she could specify the scenario as medical. Then the search engine will look it up in a medical dictionary and come up with the exact meaning. Otherwise, if she is reading a computer textbook, she may specify the scenario as computing. Then the search engine will look it up in a computing dictionary instead. This is possible because there are a lot of domain specific dictionaries or database available. There is a table on the server/web clipping program which map different user specification of context to different database. When there is only one specification from the user, the table looks what showed as follows. Scenario Computing Hi-Tech Medical Mental Default Dictionary FOLDOC online ComputerUser Hi-Tech CancerWeb on-line Human- Nature Merriam- Webster Dictionary Dictionary Medical dictionary of Dictionary mental health Table 3.1

11 For more complicated context specification, the database/dictionaries will be further divided and the mapping between specification combinations and databases/dictionaries will be more complicated too. The augmented search engine will significantly increase the hit-rate, reduce communication and power consumption. It will also make the pervasive reference wireless access more comfortable. 3.5 Web Clipping Program We implement the P-Reference using 6 different on-line dictionaries. A Palm VII(x) user can load our web clipping program into her handheld device from our project homepage ( The web clipping program was developed with the Palm Web Clipping Application Builder which is downloadable from The Palm OS Emulator(POSE) is used to emulate our programs and the wireless access. POSE is downloadable from Lin Zhong joined the Palm Alliance Program and obtained the ROM Image Files for Palm VIIx, which is necessary for emulation. The P-Ref Web Clipping a Figure 3.2 b

12 a Figure 3.3 b Scenario Domain Show images? How many to show? a Figure 3.4 b

13 Figure 3.2 a shows our Princeton P-Reference web clipping program has been installed on the Palm. Figure 3.2 b shows the interface for Princeton P-Ref 1.0. The user will select one from the 6 scenarios. If the user chooses the general, figure3.3 a shows up and ask for an input. Up to now, there is no wireless transmission. Everything is done locally. If the user inputs Operation and clicks search button, the request will be sent wirelessly to the Merriam-Webster database. Figure 3.3b shows the returned searching results for the word Operation. As there is no CGI to filter all the undesirable html features for Palms, all the html file is force into the small screen of the Palm VII. Figure 3.4a illustrates the awkwardness resulting from the absence of the CGI in the system architecture. The absence of CGI filter also significantly increases the wireless traffic as all the pictures are sent back to the user while it is of no use for her. Figure 3.4b shows the interface for the Princeton P-Ref Version 2.0, which is under development. In P-Ref 2.0, besides scenario, the user can specify the domain where the term comes from. She can specify whether the database should send back her the images in the searching results and specify the maximal number of entries to be sent back her every time. 3.6 Other implementation issues For practical or commercial use, there are a lot of other considerations for the P-Reference because of the limitation for the battery life, wireless communication bandwidth and display ability. Power efficiency for communication and computation Reducing the whole communication and computation of the palm devices during the searching process, will definitely reduce the latency and power consumption. In the P-Ref, there are several implementation choices, which reduces the wireless traffic and local display. For example, we chose to asked the user specify the scenario locally. The user does not need to get online to fill in the searching request forms, which is the normal way to do in "Yahoo" and "Google" nowadays. After the user filled in the searching terms and pushed the "Submit" button, the wireless connection is beginning to build up. There are other implementation issues concerned with the database. In the first version, we actually did nothing about the optimization of the database and CGI scripts. However, there are a bunch of good ideas. The pages sent back after a query can be split into several contiguous blocks, if they are too big. Usually the first part will be downloaded from the server, and users can decide whether to keep going on, just end the searching or skip a few pages. This service can be done by the CGI scripts, which reside on the database server. Users can even ask for any part without going through previous parts. The size of each part is supposed to fit a whole display screen of the palm. Advertisements problems To put on advertisements along with the searching process for business purpose, we can put attractive advertisement banners in the web clipping program. When a user is using the P-Ref, the advertising banners are showed from the local memory, instead of downloaded from the

14 website. As the databases are updated from time to time, the free web clipping programs are updated periodically, so are the advertisements in it. When users update their P-Ref web clipping program, the advertisements are updated without user notice. 4. Future work and conclusion The most direct future work will be to implement the CGI scripts, which optimize the html web pages for Palm users. In P-Ref 1.0, we used several on-line dictionaries for demonstration. However, they do not work ideally for Palm users. Works can be done to optimize the database, or contract with those ICPs for collaboration. Moreover, as mentioned in section 2, the context augmented search engine demands further studies for better implementation and real advantages over traditional search engines. As to P-learning, we should conclude that it doesn t come easily from e-learning. There are a lot of places to invest researches and engineering ideas. Wireless data networks, compared with the wired ones, are always short of bandwidth. Handheld devices, compared with the wired ones, are always short of power supply. It will be interesting to investigate the ways to benefit users from the pervasiveness of the wireless data networks while hiding the disadvantages from them. Our course project is just one small step in such investigation. Another thing worth mentioning is the increasing capability of handheld devices and the wireless networks. A lot of issues, which troubled us in implementing P-Ref 1.0, may not even exist after some months. In identifying the P-learning services, we should design for the future technologies and we should make scalable designs.