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    Wireless Technologies: An Overview


    Karen D. King, RDH, MHeD


    Roz Seymour, EdD, RN, CS


During the past 10 years, cellular telephones (wireless devices that can access networks and inter\intra nets) have evolved from a rarity  to an everyday accessory  These and other wireless devices prompted the International Telecommunications Union, the Institute of Electrical and Electronics Engineers, and the European Telecommunications Standards Institutes to develop standards for wireless communications.  

Users of such devices  have the flexibility, convenience, and canaccess information from any location.  Other wireless technologies include the microwave, satellite, radio frequency transmission, and various cellular services.  .  Examples of approaches to wireless activities include Wireless Local Area Networks (LANs), Infrared and Spread Spectrum Technologies, Wider Area Wireless Networking, Specialized Mobile Radio, Cellular Digital Packet Data, Microwave Technology, Satellite Technology, and Personal Communications Services (Littman, 1998). 

Wireless products are deployed in schools K Ė12, colleges, and universities where there use is  providing campus-wide connectivity for students, teachers, and administrators.  Wireless LANs  offer a lowcost solution to high speed Internet access with the flexibility to meet the needs of an everchanging educational landscape (www.aironet.com).  The integration of technology with education is rapidly changing  teaching/learning paradigms and environments.  

 Wireless technology, provides its users with access to information without looking for a place to plug in, and network managers  with the capability to  set up or augment networks without installing or moving wires.  The advantages of being wireless  include mobility, installation speed and simplicity, installation flexibility, reduced cost of ownership, and scalability.  Consequently, wireless communications are connecting more people and information, faster, and more cost effectively than ever before.   

Technical Fundamentals 

        All wireless communication, whether analog, voice, or digital data consists of electromagnetic waves traveling through the air.  These waves determine the frequency  (number) of crests that move past a point in one second.  The shortest waves have the highest frequency (number of cycles per second); the longest have the lowest frequency.  One cycle per second is called a hertz (Hz).  One kilohertz (kHz) is 1,000 cycles per second; one megahertz (MHz is a million cycles per second; and one gigahertz (GHz) is a billion cycles per second.  Wavelengths range from a high of100,000 meters (270,000 feet) to a low of 1 mm (.004 inch) and frequencies range from 3 kHz to 300 GHz.  The full range of wavelengths and frequencies is  called the spectrum.  The frequency and wavelength of different parts of the spectrum  determine how it is used.  Generally, the shorter the wave and the higher the frequency, the more limited the range (Stalling, 1998).  In the U.S., the Federal Communications Commission (FCC) regulates the spectrum; assigns frequencies and operating power and  both inspects  and regulates the use of transmitting equipment (www.fcc.gov).  Wireless telecommunications networks have been deployed in growing numbers throughout North America and elsewhere in the world.  These wireless networks evolved from early microwave and satellite forms to cellular, personal communications systems (PCS) and enhanced specialized mobile radio systems (SMR).

         Microwaves are very short waves in the upper range of the radio spectrum used mostly for point-to-point communications systems.  Microwave transmission can handle all types of information, such as voice, data, facsimiles, and video, in either an analog or digital format.  As the nation's cellular and personal communications systems grow, point-to-point microwave facilities enable these wireless systems to serve the country less populated areas on an economical basis (Gold, 2000).  Early technology limited the operations of these systems to radio spectrum in the 1 GHz range; but due to improvements in solid state technology, commercial systems are transmitting in the 40 GHz region.  This spectrum offers a variety of possibilities, such as use in, short-range, high capacity wireless systems that support educational and medical applications, and wireless access to libraries or other information databases (www.fcc.gov).  Satellite technology is another form of wireless technology, which uses microwave technology at high frequencies and is for wide area communications.  Its major advantage is that it can deliver services to remote locations which cannot be easily accessed through traditional communication methods (Littman, 1998). 

            As defined by Littman (1998), ďa wireless LAN (WLAN), is a communications network capable of supporting wire-free interconnectivity for mobile users within an office, a building, or a group of buildings in a confined geographical location such as on a university campusĒ.  A typical WLAN configuration is a backbone wired LAN that supports servers, workstations, and one or more bridges or routers to link with other networks.  A control module acts as an interface to a wireless LAN.  The control module includes either a bridge or router which then link the WLAN to the backbone. 

        Another use of WLAN technology is to connect LANs in nearby buildings.   A wireless link can be point to point between two buildings using  bridges or routers.  A wireless link can also be between a LAN hub and a mobile data terminal such as a laptop computer.   Anyone with a wireless laptop can communicate with students and colleagues and transfer data from the laptop to a desktop computer on campus  A WLAN must meet the same requirement of any typical LAN which include high capacity, ability to cover short distances, full connectivity among attached stations, and broadcast capability (Stalling, 1998). Ad Hoc Networking is a temporary network set up to meet an immediate need.  For example, a faculty group could meet in a conference room and wirelessly connect their computers in a temporary network for the duration of the meeting.

Wireless Implementation Standards

Designing network protocols and interfaces to support ubiquitous information access for mobile and wireless hosts so that computing sessions initiated in one location can continue without disruption when the user moves to a different location are under investigation (Littman, 1998).  The Wireless Application Protocol (WAP) is an emerging standard for the presentation and delivery of wireless information and telephony services on mobile phones and other wireless terminals.  WAP uses existing industry standards as the basis for its own architecture and design.  For example, a WAP gateway is required to communicate with other Internet nodes using the standard HTTP protocol.  Furthermore, the specification calls for wireless handsets to use the standard URL addressing scheme to request services.  The WAP specification is an open standard that enables public content, corporate Intranet and operator specific solutions to reach wireless subscribers.  It extends existing Internet standards, enabling application developers to tailor their content to the special needs of wireless users (www.wapforum.org). 

Third generation (3G) mobile devices and services are transforming wireless communications into on-line, real-time connectivity.  It will allow users to have immediate access to location specific services that offer information on demand.  The rapid and efficient deployment of new wireless data and Internet services has emerged as a critical priority for communications equipment manufacturers.  Network components that enable wireless data services are fundamental to the next generation network infrastructure.  The recently adopted global 3G wireless standard will address emerging user demands and provide new services.  The concept of 3G wireless technology represents a shift from voice-centric services to multimedia oriented services.  In addition, heavy demand for remote access to personalized data is fueling the development of applications such as SAP and multimedia management to complement the 3G protocols.  Complementary standards, such as Bluetooth, will enable interoperability between a mobile terminal and other electronic devices such as a laptop, desktop, and peripherals, providing added convenience to the consumer and allowing for the synchronization and uploading of information at all times (www.trillium.com).

            Bluetooth wireless technology is a standard, as well as a specification for short-range radio links between mobile computers, mobile phones, and other portable devices.  The Bluetooth Special Interest Group is an industry group consisting of leaders in the telecommunications, computing, and network industries that are driving development of the technology and bringing it to the public.  These companies consist of Intel, 3COM, Ericsson, IBM, Motorola, Nokia, and Toshiba (www.bluetooth.com).  Bluetooth technology was developed to provide a wireless connection between small mobile devices and their peripherals.  The targets were mobile computers, the mobile phones, small personal digital assistants, and peripherals.  It allows for the replacement of cables that connect one device to another with one universal radio link.  It also provides a universal bridge to existing networks, a peripheral interface, and a mechanism to form small private groupings called piconets of connected devices away from a fixed network infrastructure.  The goal of Bluetooth is to emulate the cost, security, and capabilities of the cables carried by mobile travelers.  The Bluetooth usage model is based on connecting devices, and is focused on three broad categories.  They are voice/data access points, peripheral interconnects, and Personal Area Networking (PAN).  The voice/data access points involves connecting a computing device to a communicating device by a secure wireless link.  For example, a mobile computer could establish a wireless link to a mobile phone and connect to the Internet for e-mail access.  The mobile phone acts as an access point.  Bluetooth envisions public data access points such as pay phones equipped with Bluetooth modems.  Peripheral interconnects involve attaching devices together.  Keyboards, mice, scanners, printers, and other peripherals work over a wireless link.  Additionally many of these devices can be used in multiple markets.  For example, a Bluetooth enabled headset could be used in the office or when mobile the same headset could be used to interface with a cellular telephone. Quick secure document exchange can be accomplished on a private piconet (Kardach, 2000).   

Wireless Broadband access technology has the capabilities to deliver service to the markets not served by other technologies and compete on reliability and price.  Broadband digital wireless systems operate in the microwave regions above 1 GHz.  They can be delivered through multi channel multipoint distributions system (MMDS), and local multipoint distribution services (LMDS).  The LMDS are the newest type of broadband wireless network, and is set up on the hub and spoke model with a base station antenna transmitting and receiving to and from individual subscribers.  Most LMDS systems use the asynchronous transfer mode (ATM) protocol at the core of the network.  This allows services to be provided on a bandwidth on demand basis, which accommodates the need for multimedia applications and differences in user traffic patterns.  MMDS has been historically used to deliver one-way TV cable broadcasts to homes.  It can now provide two-way digital broadband access after the FCC revised its one-way restriction on the frequency band in 1998.  MMDS is delivered via a rooftop antenna to a box in the userís location.  Its signal can travel up to 30 miles, and can be deployed in metro areas with only a few base stations.  Fading and line-of-sight concerns remain a consideration with the implementation of this technology (Smith, 2000). 

No current satellite data service has the speed or return path capabilities to compete with cable, DSL, or LMDS in the larger broadband marketplace.  Satellite systems are costly to launch, but  Satellite do offer high bandwidth, a high degree of frequency reuse, and unrivaled geographical coverage.  Although expensive, the amount of infrastructure required to provide a satellite service is much less than in terrestrial networks.  As the market moves more and more toward global services, satellite technologies will likely become a much bigger contender for a share of the wireless technology marketplace (Fowler, 1998).   

Wireless Applications and Providers

Transmission. Infrared electromagnetic waves have frequencies higher than microwaves but lower than the visible spectrum.  Infrared transmission is used for wireless LANs, as well as for point-to-point communications with portable devices.  Infrared limitations include signal fading and line-of-sight requirements.  Spread spectrum is a wireless communication in which the frequency of the transmitted signal is deliberately varied according to a specific mathematical function.  The signal is spread over a large segment of the electromagnetic radiation spectrum to prevent it from being intercepted.  Although it uses much more bandwidth than a constant signal a major advantage is that the signals produced can penetrate walls and other obstructions (Littman, 1998).  Specialized Mobile Radios (SMRs) are primarily used for voice communications, but systems are also being developed for data and facsimile services.  Additionally, the development of a digital, rather than analog, SMR marketplace is allowing new features and services, such as two-way acknowledgment paging and inventory tracking, credit card authorization, automatic vehicle location, fleet management, inventory tracking, remote database access, and voicemail.

        Wireless communication companies have multiplied quickly.  There are more than 50 million wireless telephone users in the US.  Satellite systems, such as Iridium and Teledesic are developing worldwide data and communications services.  As the technology  is more reasonably priced, wireless could  replace wired telephones as the medium of choice in America.   Wireless technology uses in education can now offer  low-cost solutions to high-speed information access with the flexibility to meet the needs of the ever-changing educational landscape.  A growing number of applications required by businesses and educational institutions require mobility and simultaneous access to a network.  Until recently, if an application required information from a central database, it had to be connected to a wired network.  Wireless LAN enables mobile computers to be in constant contact with servers and each other.  This section  describes some wireless applications in current use in the corporate  as well as the education arenas.  

        The mobility of wirelessness is needed and could be  used in health care facilities, warehouses, restaurants, and in real estate and sales.  Having the flexibility and freedom to move laptop computers anywhere in any  environment, enhances productivity.  The transportation industry requires mobility and real time connectivity over large areas.  Retail businesses require flexible networking, fast reconfiguration and redeployment of resources.  Health care providers need to have easy  access to many types of medical records and  to  specialists for assistance as well as to computer-controlled medical equipment, from the point of care.  Wireless access can also be effective in manufacturing facilities where robots and other mobile automated equipment are already used. 

            In January 2000, IBM and Motorola announced a partnership under which the two companies will  develop wireless Internet technology for cars.  Users will be able to send email, check on stocks, or engage in impulse buying while they drive.  The first  of these  devices could appear in cars as early as 2002 (www.wirelesstcp.net). 

            Personal Digital Assistant (PDA) development is advancing rapidly because of advances in wireless technology.  Using a PDA with a wireless Internet connection, one can check e-mail, access web channels, browse web sites, or synchronize the PDA with a host computer or server.  The range of PDA task capabilities is increasing quickly as software innovations for such assistants blossoms with access and use.  Bluetooth technology, for example,  enables PDAs to exchange information, connect to the Internet or LANs, or conduct e-commerce. Cellular Digital Packet Data (CDPD) is a packet data protocol designed to work over the original cellular network or as a protocol for a digital air interface technology used in cellular and personal communications services. The wireless mobile technology with the fastest data rate used in the United States at this time is the Cellular Digital Packet Data (CDPD), which has a top rate of 19,200 bps.  At this time, CDPD coverage is limited to major cities. 

Wearable wireless computer devices have been developed and tested at Carnegie Mellon University.  The military, business, and industry have used these 2-pound devices for a variety of purposes.    To accommodate  workers, who need their hands free Carnegie Mellon designed wearable computer devices that operate by voice or handwriting recognition.  Head-mounted  computer monitors work like a miniature dashboard, allowing users to obtain information without blocking their vision.  Current users of wearable devices include the National Science Foundation, the Defense Advanced Research Project Agency, Intel, AT&T and IBM.  One  disadvantage to the use of  wearable computers is the current lack of access to high-speed wireless bandwidth (www.wirelesstcp.net). 

There are many more uses of wireless technology in academe than can be described here. A few  examples will be provided. The Florida State University College of Law in Tallahassee has installed a wireless LAN to give its students wireless computer connectivity on its campus.  Professors can download casework directly to students through the college's Intranet.  In the classroom, professors can send real time handouts directly to student laptops.  The wireless connection offers  total freedom and access to the network  from anywhere on campus, from classroom to courtyard to law library.  The school is also doing a pilot  distance learning experiment.  Students are connected via  wireless devices to an ISDN line and are taught remotely by a Chicago Kent College Law professor.  With the wireless infrastructure, the curriculum and support material can be delivered real-time via the Internet.  Aironet and the Florida State College of Law are also developing a joint pilot project to test the efficacy of wireless LAN devices in the  Tallahassee municipal court system.

        When students at Greenville College in Greenville, Illinois need to access the Internet, they simply turn on their computers-anytime, anywhere on campus.  The wireless network technology allows students, teachers and college administrators to roam freely around campus using their laptop computers in any classroom, campus dorm room, or sitting on a park benche in the middle of a campus lawn.  Students  have instant access to information, and  take tests and quizzes on line, attend classes outdoors, or in  venues other than the traditional classroom setting. Princeton's Computer Science Department decided to test the efficacy of wireless connections to the Local Area Network (LAN) linking departmental offices and conference facilities on several floors.  Whether engaged in research or involved in other departmental activities, faculty and students can carry laptop computers equipped with wireless LAN adapters from room to room and floor to floor while staying wirelessly connected to the network.  Because of the pilot study's success, the department has begun to expand the wireless network.  Plans are being developed to design a wireless Wide Area Network (WAN) that will reach from the department server to remote sites, including faculty members' homes.

         A partnership between East Carolina University and Ericsson Wireless Internet Solutions is targeting geographically displaced learners and mobile professionals.  This project develops a high-speed wireless Internet system and an intelligent instructional tool set for providing courses worldwide.  It will minimize learnerís need for a hardwire internet connection,  provide an intelligent instructional tool set and student assessment system for pacing coursework to each studentís ability, and deliver multimedia content without internet bandwidth limitations.  Within three years, nine universities  plan to  implement  wireless solutions  to  deliver up to 40 credited hours. 

         Virginia Tech purchased four A-block Local Multipoint Distribution Services (LMDS) licenses covering 16,500 square miles of rural Southwest Virginia and portions of Tennessee and North Carolina to create a regional test bed for broadband wireless technology.  The licenses give faculty and students the unique opportunity to do applied research in areas such as LMDS signal propagation, systems and components, and antenna design. 

         Students can insert a wireless card into a laptop, turn on the machine, and instantly connect to a network or the Internet.  This ease of access to the network encourages greater use of laptops and greater integration of the technology into the curriculum.  Faculty members who have hesitated due to the physical effort of getting a room of students online are more likely to consider assignments to use the Internet.  Ease of use also encourages spontaneity in or out of the classroom.  Students and faculty can turn to their laptops to collaborate or answer questions as soon as the need arises.  Easy and fast access and set up is valuable for groups of students.  Wireless technology can free up as much as an hour a day for students who are using laptops at several different times each day.  Students and faculty can move from classroom to office or conference room as they choose without logging on or off and rebooting their machines  A major goal of the research is to work with industry to accelerate the development of the technology toward lower-cost components and to  support the technical and financial viability of LMDS in the rural market.  In addition to the research value from the licenses, the University is supporting economic development by providing its citizens and communities with early access to the emerging technologies of LMDS. 

            In addition the system will be used to extend the stateís public ATM network, so that broadband connectivity may be brought to more locations, especially as a way to provide economical access to new network-based learning (www.aironet.com).

Going Wireless: Advantages and Disadvantages  

            As with any technology, there are both benefits and limitations.  Wireless communication  is not exception. Like many technological innovations before it  has rapidly  advanced to the point of users not questioning what can be done with wireless technology, but rather what method to use and then how best to use the method chosen.    There are no wires  from or to any machine from anywhere, which is an advantage in  any environment. Wireless systems are commonly thought to be more expensive initially than wired systems, but may actually be less expensive when setting up a new system in an existing facility.  For example, in older buildings where cable access is not possible or is to costly the relocation of wireless devices is simple and there are no additional  rewiring costs or downtime with such a move.  With wireless  access new devices can be added or removed without disruption to the remaining system.  After the initial financial expenditure of setting up a wireless system, the cost of running and maintaining a wireless communications solution is minimal  One problem with the technology itself is the limited spectrum available for communications.  Splitting-up the environment into a number of small cells increases overall accessible bandwidth of the communication system, but also increases the cost as more cell sites are required.  

        Disadvantages of wireless systems are that they  slower than existing wireless technology which does not offer the performance of wired systems. The generate sizeable radio waves, and can be disrupted by interference. How much slower can depend on the tasks being done.  There is little difference in simple tasks such as checking e-mail and browsing the web.  The more complex tasks of downloading large files and using multimedia software, or multi-tasking  require more time on wireless systems.  While wireless technology eliminates the need for a cord connecting the user to the network, users still need to plug their laptops into an electrical outlet unless their batteries are charged.  Without charged batteries, electrical wires remain (www.ccds.cincinnati.oh.us). 

        When a large number of devices are transmitting, a sizable amount of radio power is  generated.  The effects of radio communication on human health are being examined, but much more research is needed is this area.  Interfering signals generated by other devices in a business or education environment, which can temporarily disrupt a communication link through the noise generated. 

        Finally, the unconstrained nature of the communication medium of radio requires the issue of network security to be addressed.  Verification of communication entities must  be performed to ensure that only registered devices may communicate using the network, and that only registered devices receive the data.  Some form of encryption may be required for communications to avoid interception of data transmitted by devices not officially taking part in the communications (www.wirelesstcp.net).

Security Considerations in Wireless Technology

         Being unwired offers easy access to  data, information, and to the conducting of transactions.  Being unwired also presents  greater security risks than the wired world.  The WAP gateway is  open to security breaches.  In other words,  a breakpoint in the security of such a system occurs where the wireless transport layer  changes to a secure socket layer to secure the connection between the WAP gateway and the server.  Verisign has deployed a mini-certificate issuance service for WAP gateways.  The certificates will support gateway assisted SSL and gateway assisted object signing. 

Digital signatures can also be used in wireless devices.  The wireless client contains a private key and digital signing logic, but does not need to store or process a certificate for the corresponding public key.  The certificate can be stored in a directory within the wired infrastructure, and be picked up and used by application servers whenever a userís digital signature needs to be verified.  This enables servers to use the same functions to verify digital signatures from wireless clients as they use for verifying digital signatures from wired clients (www.wapforum.org). 

A wireless public  infrastructure of key pairs provides four requirements of electronic security (using cryptography, digital signatures, and digital certificates): confidentiality, authentication, integrity, and non-repudiation.  These key pairs are linked mathematically using asymmetric cryptography and each key pair is unique.  The originator of a message uses the private key to digitally sign the message.  The digital signature is proof of that userís identity, the equivalent of a legal, handwritten signature.  The recipient of the message  verifies the signature using the corresponding public key.  Because it is the only matching key, only it can verify the signature and establish that the originator is authentic and the data is not altered (Sing, 2000).  This technology enables secure mobile transactions to all wireless applications. 

        Wireless communications are open to other potential security risks. An intruder does not need physical access to the traditional wired network in order to gain access to data communications.  To protect against any potential security issues, 802.11 wireless communications have a function called WEP (Wired Equivalent Privacy), a form of encryption providing privacy comparable to that of a traditional wired network.  If the wireless network has information that needs to be secure then WEP needs to be used to ensure the data is protected at least at traditional wired network levels.  In addition, it should be noted that traditional Virtual Private Networking (VPN) techniques will work over wireless networks in the same way as they do over traditional wired networks (Sing, 2000).

            In summary, wireless technology has advanced rapidly  since its inception.   this innovationís uses have expanded  communication systems producing exciting possibilities for applications and implementations in  corporate, academic, and many other environments.  It will continue to be  a challenge for potentials users to remain current  during  such rapid technological expansion.