¶ … Wireless LANs Replace Wired LANs?
The convenience of wireless communication is so overwhelmingly obvious that given a choice, and provided there are no price constraints, almost everyone would prefer wireless instead of wired communication. This is reflected in the widespread use of devices such as remote control for TV, cellular telephones, pagers, and remote garage openers. The flexibility, mobility, and convenience that such 'wire-less' devices bring to our lives are simply magical. Who wouldn't like to extend such convenience to their working lives by, e.g., being able to access the Internet from almost anywhere? Or to be able to access their company's data from, say the cab downstairs? Such convenience is possible through the technology known as Wireless Local Are Networks (WLANs), which is an on-premise data communication system that reduces the need for wired connections besides making new applications possible. The technology has made its presence felt in 'vertical' markets and is poised to find wider applicability in a wide range of businesses and office settings. This research paper discusses what the technology is about, and describes its benefits and applications. It looks at some of the constraints that are holding the technology back and their solutions. Finally, it discusses the important question of whether Wireless LANs can replace Wired LANs or if the technology is another 'flash in the pan' that is destined to fizzle out like certain other seemingly promising communication technologies that failed to deliver.
What is a Local Area Network?
We have already seen that WLAN is a Wireless Local Area Network -- so before describing WLAN, let us look at what network and Local Area Network (LAN) mean? A network is defined as any conglomeration of parts working together in a predictable order; in computer terms a group of computers connected by a common topology that enables data to be transmitted.
The primary purpose of a network being to link similar items together to ensure reliable service. (Hayden, 1988 p. 4). In a computer network, information must be delivered reliably and consistently, with a common standard to enable the computers to identify and name each other, and parts of the network. Taking our definition of Network further, a Local Area Network (LAN) is a group of computers linked through a network at a single site. Besides being located at a single physical location LANs are characterized by data transfer at very high speeds (Hayden, 1998, p. 11).
What is Wireless LAN?
A wireless LAN (WLAN) is a data communication system that may be an extension to, or an alternative for, a wired LAN installed within a building or in an area such as a campus. In WLANs data is transmitted or received 'on air' through electromagnetic waves, minimizing the need for wired connections. WLANs are thus flexible communication systems that combine data connectivity with user mobility and are characterized by simplified configuration. ("What is a Wireless LAN?" 2001)
Applications for Wireless LANs
WLAN is particularly useful for mobile users and enables them to access information and network resources while attending meetings, moving between other locations, or while collaborating with other users. Benefits of WLANs are not limited to mobility of the users only, since the WLAN network is itself movable. (Ibid. 2001. "Overview"). We had noted in the "Introduction" to this paper that WLANs have already made their presence felt in the 'vertical' markets, which refer to the health-care, retail, manufacturing, warehousing, and academic services. These particular markets had a more pronounced need for mobile data transfer and were, therefore, early users of WLAN. They have benefited by the increasing use of hand-held devices and notebook computers for transmitting real-time data to centralized hosts for processing made possible by Wireless LANs. WLANs are now poised to move out of these markets and are increasingly recognized "as a general-purpose connectivity alternative for a broad range of business customers." (Ibid.) According to IDC research projections the worldwide LAN market is expected to grow from $1.45 billion by end of 2001 to $3.72 billion by 2006. ("Wireless LANs to Make Mark." 2002).
Who can Benefit from WLANs?
Doctors and nurses in hospitals can increase their productivity because hand-held or notebook computers with wireless LAN capability can deliver patient information instantly.
Consulting or accounting audit engagement teams as well as small workgroups can increase productivity with LAN due to its quick network setup capability.
Network managers in dynamic environments minimize the overhead of moves, add-ons, and changes with wireless LANs, reducing the cost of LAN ownership.
Training sites at corporations and students at universities can use wireless connectivity for easy access to information, information exchanges, and learning.
Installing networked computers in older buildings or temporary facilities is more cost-effective, using wireless LANs as it does not involve installing wires and damage to buildings.
Retail store owners can use wireless networks...
("Wireless Local Area Networks -- For Homes & Offices" 2002)
Benefits of Wireless LANs
The benefits of quick and easy data sharing are reflected in the burgeoning growth of the Internet, computer networking in businesses and offices, and other online resources. Wireless LANs are just another option for users to get prompt access to shared data without having to arrange or look for places to plug-in. It also provides the Network Managers the option to install or expand an existing network without having to install wires. As compared to the traditional wired LANs systems, wireless LANs provide the following benefits:
Mobility: It is the most important advantage of Wireless LAN systems as it provides users with access to real-time information from anywhere. The boost that mobility gives to productivity and service in an organization is just not possible with wired networks.
Installation Speed and Simplicity: Wireless LAN systems can be installed very promptly and easily, as it does not involve pulling cable through walls and ceilings.
Installation Flexibility: Wireless technology takes the network to places where wire cannot go.
Reduced Cost-of-Ownership: Although initial investment costs for wireless LAN hardware is usually higher than the cost of wired LAN hardware, overall expenses in terms of life-time costs is often significantly lower, especially in dynamic organizations that require frequent re-location, add-ons, and changes.
Flexibility of Configuration: This is also an important characteristic of Wireless LAN systems. They can be configured in a variety of topologies to meet the needs of specific applications and installations. Configurations can be easily changed in Wireless LANs as compared to Wired LANs. (Ibid. 2002-Why Wireless?)
WLAN Technology Options
There are a number of technology options available to manufacturers of wireless LANs while designing a wireless LAN solution, each technology having its pros and cons.
Spread Spectrum
Most wireless LAN systems are based on the spread-spectrum technology. It is a wide-band radio frequency technique that was developed by the military for use in reliable, secure, mission-critical communications systems. Spread-spectrum consumes more bandwidth than transmission but the trade off increases reliability, integrity, and security of the transmission. The wider bandwidth produces a louder signal that is easier to detect. If a receiver is not tuned to the right frequency, a spread-spectrum signal sounds like background noise.
Narrow-band Technology
In the narrow-band technology the radio signal frequency is kept as narrow as possible to just pass the information. Undesirable cross talk between communications channels is avoided by carefully coordinating different users on different channel frequencies.
Privacy and noninterference are accomplished by the use of separate radio frequencies. The radio receiver filters out all radio signals except the ones on its designated frequency.
Frequency-Hopping Spread Spectrum Technology
Frequency-hopping spread-spectrum (FHSS) employs a narrow-band carrier that changes frequency in a pattern recognized by the transmitter and receiver. It maintains a single logical channel when properly synchronized. FHSS appears to be short-duration impulse noise to all receivers except to those who know its frequency pattern.
Direct-Sequence Spread Spectrum Technology
Direct-sequence spread-spectrum (DSSS) transmits the information in 'bit patterns' that is also called a chip or chipping code. DSSS transmission has the advantage that even if one or more bits in the chip are damaged during transmission, the original data can be recovered without the need for retransmission. Its disadvantage is that it uses more bandwidth. DSSS appears as low-power wide-band noise to receivers other than for which it is intended.
Infrared Technology
Infrared (IR) systems use very high frequencies, just below visible light in the electromagnetic spectrum, to carry data. Like light, IR cannot penetrate opaque objects and has very limited range (3 ft). This technology is, therefore, only occasionally used in specific WLAN systems. Its advantage is that it is inexpensive but is impractical for mobile users. It is used only to implement fixed sub-networks.
Security Concern: Major Drawback
Since Wireless Local Area Networks (WLANs) employ data transfer 'over the air' via electromagnetic waves security of the data transfer has always been the number one concern among its users and perhaps the biggest stumbling block in its unfettered adoption by businesses.
As explained under the "WLAN technology Options"…
