Wireless Local Area Networks

1. Executive Summary

 

2. Terms of Reference

 

3. Findings

This Paper deals with Wireless LANs as a technology and tool explaining it’s power to extend benefits of network connectivity to mobile users. Setting aside all the technical jargon it has what it takes to take Information Superhighway to the twenty first century. Imagine you being able to check mail while you are having a pizza at your faviourite deli! Well, that’s Wireless LAN for you at ground level.

The paper broches with a bird’s eye view of Wireless LANs. The wireless LANs are used as suppliment to or as option for conventional wired LANs. They are quite transperant in operation as they do not need any different Operting System. The major vantagepoint being wirelessness and hence freedom of movement. This can be used as augment to wired LAN in an enviornment where user mobility is highly desirable. As medium for data transfer is air, which obviously does not require any maintainance wireless LANs come out as winner in this respect too. The major apprehension that is widely felt about such networks is their vulnerabilty againest miscreants and security issues. But contrary to this view, wireless LANs can be easily managed safely and securely. Maybe better than wired LANs as more control data and encryption methods are used.

Thw working of WLANs is similar to that of radio station, with a difference that every client is able to transmit as well as receive the signals. The electromagnatic waves that are usd for data tranfer are of much higher frequency than those used in radio stations.

This paper also dwells upon various performance criteria that one should take into account while evaluating WLANs. Entire gamut of these, like area of coverage, interoperability, security, reliability actually strengthen the fact that wireless LANs have added advantages over conventional LANs.The WLAN can be configured as per network enviornment and also can be customised to the needs of individual clients.

Further it takes you on a brief ride through the technology that makes this possible. The technical paraphrenalia is simplified and explained as much as possible. This explains various technologies such as narrowband technology, spread spectrum and infranred technology are available as options.

This paper incarporate tables that serve to present relevent information at one go. The table

about various products available and their respective prices has been used from the results published by firm Frost and Sullivan. There is also a table that shows various regional standards for power parameters of WLANs. Finally a table about products offered by various companies are listed at the end.

As with any developing technology with many market players, it is very necessary to regularise and set industry standards in WLANs. IEEE 802.11 is answer to this question.

These are the standards which are curruntly used and are in process of being finalised. This paper lists these standards in brief. These standards are used as backbone and are very important for sake of interoperability between various networks developed by different companies.

Finally it hints at nature of things to come. The new standard backed by Lucent Technologies and Aeronet among other companies aims at making WLANs more user friendly. This is known as Internet-Access Point Protocol (IAPP). With that the future certainly looks promising!

This paper is an effort to introduce the reader to a nescent and briskly expanding world of wireless local area networks. It also serves to give brief idea about underlying techonology and various performance parameters. It may be noted that this work is culmination of going through various sources of information on specifed topic which are listed in bibliography.

The purpose of this paper is to define wireless LANs, to introduce the basics behind wireless LANs and to give an overview of how they work. Already market serveys have predicted whopping six-fold increase in WLAN business, reaching more than $2 billion in revenues. With that much money at consideration there is already lot of activity generated in this area of business. Cost of installing and maintaining a wireless LAN generally is lower than the cost of installing and maintaining a traditional wired LAN hence more and more companies are implementing this new LAN configuration.

A wireless LAN (WLAN) is a networking method that delivers all benefits of a local area network (LAN) with one very important advantage - no wires. A wireless local area network (WLAN) is a flexible data communications system implemented as an extension to or as an alternative for, a wired LAN. Using radio frequency (RF) technology, wireless LANs transmit and receive data over the air, minimizing the need for wired connections. Thus, wireless LANs combine data connectivity with user mobility. Wireless LANs have gained strong popularity in a number of vertical markets, including the health-care, retail, manufacturing, warehousing, and academia. These industries have profited from the productivity gains of using hand-held terminals and notebook computers to transmit real-time information to centralized hosts for processing. Today wireless LANs are becoming more widely recognized as a general-purpose connectivity alternative for a broad range of business customers.

No wires means that you now have the flexibility to immediately deploy workgroups wherever and whenever needed. Wireless LANs allow different workstations to communicate and to access a network using radio propagation as a transmission medium. The WLAN can then be connected to an existing wired LAN as an extension or it can act as a standalone network.

The advent of internet and it’s exponential growth in all areas of our lives prove the advantages of shared data systems and networking. Imagine consumer being able to check prices in K-mart while shopping in Sears. Well, that’s wireless LAN for you at ground level! With wireless LANs, users can access shared information without looking for a place to plug in, and network managers can set up or augment networks without installing or moving wires.

Wireless LANs offer the following productivity, convenience, and cost advantages over traditional wired networks:

• Mobility: Wireless LAN systems can provide LAN users with access to real-time information anywhere in their organization. This mobility supports productivity and service opportunities not possible with wired networks.
• Installation Speed and Simplicity: Installing a wireless LAN system can be fast and easy and can eliminate the need to pull cable through walls and ceilings.
• Installation Flexibility: Wireless technology allows the network to go where wire cannot go.
• Reduced Cost-of-Ownership: While the initial investment required for wireless LAN hardware can be higher than the cost of wired LAN hardware, overall installation expenses and life-cycle costs can be significantly lower. Long-term cost benefits are greatest in dynamic environments requiring frequent moves and changes.
• Scalability: Wireless LAN systems can be configured in a variety of topologies to meet the needs of specific applications and installations. Configurations are easily changed and range from peer-to-peer networks suitable for a small number of users to full infrastructure networks of thousands of users that enable roaming over a broad area.

How Wireless LANs Work:

Wireless LANs use electromagnetic airwaves (radio or infrared) to communicate information from one point to another without relying on any physical connection. Radio waves are often referred to as radio carriers because they simply perform the function of delivering energy to a remote receiver. The data being transmitted is superimposed on the radio carrier so that it can be accurately extracted at the receiving end. This is generally referred to as modulation of the carrier by the information being transmitted. Once data is superimposed (modulated) onto the radio carrier, the radio signal occupies more than a single frequency, since the frequency or bit rate of the modulating information adds to the carrier.

Multiple radio carriers can exist in the same space at the same time without interfering with each other if the radio waves are transmitted on different radio frequencies. To extract data, a radio receiver tunes in one radio frequency while rejecting all other frequencies.

In a typical wireless LAN configuration, a transmitter/receiver (transceiver) device, called an access point, connects to the wired network from a fixed location using standard cabling. At a minimum, the access point receives, buffers, and transmits data between the wireless LAN and the wired network infrastructure. A single access point can support a small group of users and can function within a range of less than one hundred to several hundred feet. The access point (or the antenna attached to the access point) is usually mounted high but may be mounted essentially anywhere that is practical as long as the desired radio coverage is obtained.

End users access the wireless LAN through wireless-LAN adapters, which are implemented as PC cards in notebook or palmtop computers, as cards in desktop computers, or integrated within hand-held computers. Wireless LAN adapters provide an interface between the client network operating system (NOS) and the airwaves via an antenna. The nature of the wireless connection is transparent to the NOS.

Wireless LANs can be simple or complex. At its most basic, two PCs equipped with wireless adapter cards can set up an independent network whenever they are within range of one another. This is called a peer-to-peer network. On-demand networks such as in this example require no administration or pre configuration. In this case each client would only have access to the resources of the other client and not to a central server.

Installing an access point can extend the range of an ad hoc network, effectively doubling the range at which the devices can communicate. Since the access point is connected to the wired network each client would have access to server resources as well as to other clients. Each access point can accommodate many clients; the specific number depends on the number and nature of the transmissions involved. Many real-world applications exist where a single access point services from 15-50 client devices.

Access points have a finite range, on the order of 500 feet indoor and 1000 feet outdoors. In a very large facility such as a warehouse, or on a college campus it will probably be necessary to install more than one access point. Access point positioning is accomplished by means of a site survey. The goal is to blanket the coverage area with overlapping coverage cells so that client might range throughout the area without ever losing network contact. The ability of clients to move seamlessly among a cluster of access points is called roaming. Access points hand the client off from one to another in a way that is invisible to the client, ensuring unbroken connectivity.

To solve particular problems of topology, the network designer might choose to use Extension Points to augment the network of access points. Extension Points look and function like access points, but they are not tethered to the wired network, as are APs. EPs function just as their name implies, they extend the range of the network by relaying signals from a client to an AP or another EP. EPs may be strung together in order to pass along messaging from an AP to far-flung clients, just as humans in a bucket brigade pass pails of water hand-to-hand from a water source to a fire.

One last item of wireless LAN equipment to consider is the directional antenna. Let’s suppose you had a wireless LAN in your building A and wanted to extend it to a leased building, B, one mile away. One solution might be to install a directional antenna on each building, each antenna targeting the other. The antenna on A is connected to your wired network via an access point. The antenna on B is similarly connected to an access point in that building, which enables wireless LAN connectivity in that facility.

The keystone to a wireless LAN is the cell. The cell is the area where all wireless communication takes place. In general a cell covers a more-or-less circular area. Within each cell there are radio traffic management units also known as Access Points (repeaters) as explained above. The Access Point in turn interconnects cells of a wireless LAN and also connects to a wired Ethernet LAN through some sort of cable connection.

The number of wireless stations per cell is dependent on the amount of data traffic (and the type of data traffic). Each cell can carry anywhere from 50 to 200 stations depending on how busy the cell is. To allow continuous communication between cells, individual cells overlap. Cells can also be used in a stand-alone environment to accommodate traffic needs for a small to medium sized LAN between workstations and/or workgroups. A stand-alone cell would require no cabling. Another option is wired bridging. In a wired bridging configuration each access point is wired to the backbone of a wired Ethernet LAN (see figure 1). Once connected to a wired LAN, network management functions of the wired and the wireless LANs can be controlled. Wireless bridging is also an option, which allows cells to be connected to remote wireless LANs. In this situation networking can stretch for miles if it were linked successively and effectively from access point to access point. Finally by connecting several Access Points to external directional antennas instead of their built-in omni-directional antennas access points can provide multi-cells. This is useful for areas of heavy network traffic since with this configuration they are able to automatically "choose" the best Access Point to communicate with. Roaming can also be provided for portable stations. Roaming is seamless, and it allows a work session to be maintained when moving from a cell to a cell (there is a momentary break in data flow).

Range/Coverage: The distance over which RF and IR waves can communicate is a function of product design (including transmitted power and receiver design) and the propagation path, especially in indoor environments. Interactions with typical building objects, including walls, metal, and even people, can affect how energy propagates, and thus what range and coverage a particular system achieves. Solid objects block infrared signals, which imposes additional limitations. Most wireless LANs use radio frequencies (RF) to function (normally in the range of 2.4GHz). RF is used because of its ability to propagate through objects. In wireless LAN objects blocking the path of communication between access points limit the range that a wireless LAN can cover. Typically the radius of coverage is anywhere from 100 feet to more than 300ft. Coverage can be extended via roaming which was defined above.
Throughput: Airwave congestion contributes to data rates for a wireless LAN. Typical rates range from 1 to 10Mbps. Just like in wired Ethernet LANs, wireless LANs slow down as traffic intensifies. Traditional Ethernet LANs users though experience minimal difference in performance when going from wired to wireless LANs.
Integrity and Reliability: Radio interference can cause degradation in throughput. Such interference is rare in the workplace and existing robust designs of WLAN prove that such problems are nothing compared to similar problems in existence with cellular phone connections. After all wireless data technology has been used by the military for more than fifty years.
Interoperability: Wireless and wired infrastructures are interoperable yet dependent on technology choice and vendor implementation. Currently vendors make only their products be interchangeable (adapters access points etc.). Wireless networks pose a set of interoperability challenges that do not apply to hard-wired, infrastructure network products. With client units that are mobile more often than not, the fluid, ever-changing state of the network requires detailed definitions of interoperability.

The IEEE 802.11 standard is an important step towards the development of interoperable products, but it is no panacea or silver bullet. The practical evolution of the standard to the point that compliance to the standard is a guarantor of interoperability may take a significant amount of time. In the meantime, the OpenAir standard offers a means to build a wireless LAN that supports products from a variety of vendors, with the clear advantage of proven interoperability.

Simplicity: Wireless LANs due to their nature are transparent to user’s networking operating systems (OS). This allows excellent compatibility to existing OS and minimizes having to use any type of new OS. Also since only the access points of wireless LANs require cabling, moving, adding and setting up is much easier. Finally the portable nature of wireless LANs allows networking managers to setup systems at remote locations.
Security: The military has been using wireless technology for a long time, hence security has been a strong design criterion when designing anything that is wireless. Components are built so that it is extremely difficult for "eavesdroppers" to listen in on wireless LAN traffic. Complex encryption makes unauthorized access to network traffic virtually impossible. As this is a very important issue it is delt separately further.
Cost: Infrastructure costs are dependent on the number of access points, and the number of wireless LAN adapters. Typically access points range anywhere from $1,000 to $2,000. Wireless LAN adapters for standard computer platform range anywhere from $300 to $1,000. Installation and maintenance costs vary depending on the size of the LAN. Installation costs of installing and maintaining a wireless LAN is lower in general compared to costs of installing and maintaining a traditional wired LAN.

Scalability: Complexity of each network configuration varies depending on the number of nodes and access points. The ability of wireless LANs to be used simple or complex is what makes them so influencial to current offices hospitals and universities.
Power Consumption: Power consumption of a wireless LAN is very low compared to that of a hand-held cellular phone. Wireless LANs must meet greatly strict standards posed by government and industry regulations hence making them a safe device to have around you at a workplace. Finally no health affects have ever been attributed to wireless LANs.

There is a range of available technologies out there for manufacturers to select from. For each individual technology there are individual advantages and limitations. Narrowband Technology

This technology uses narrow frequency on the radio signal. Communications channels are apportioned to this signal each with different channel frequencies. Undesirable crosstalk between communications channels is avoided by carefully coordinating different users on different channel frequencies. A private telephone line is much like a radio frequency. When each home in a neighborhood has its own private telephone line, people in one home cannot listen to calls made to other homes. This technology works just like a radio station. Each channel in this technology could be similar to a radio station on your FM stereo. Except the frequencies used in narrowband technology are much higher (in the GHz range). In a radio system, 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.

Most wireless LAN systems use spread-spectrum technology, a wideband radio frequency technique developed by the military for use in reliable, secure, mission-critical communications systems. Spread-spectrum is designed to trade off bandwidth efficiency for reliability, integrity, and security. In other words, more bandwidth is consumed than in the case of narrowband transmission, but the tradeoff produces a signal that is, in effect, louder and thus easier to detect, provided that the receiver knows the parameters of the spread-spectrum signal being broadcast. If a receiver is not tuned to the right frequency, a spread-spectrum signal looks like background noise. There are two types of spread spectrum radio: frequency hopping and direct sequence.

1)Frequency Hopping Spread Spectrum Technology (FHSS) uses frequency diversity to combat interference. Basically, what happens is that the incoming digital stream gets shifted in frequency a certain amount (determined by a code that spreads the signal power over a wide bandwidth). If an unintended receiver sees the signal it will appear as a short duration impulse noise.

2) Direct-Sequence Spread Spectrum Technology (DSSS) generates a chipping code, which encodes each data bit. Effectively this produces a low power wideband noise in the frequency domain (thus rejected by narrowband receivers). The greater the number of chips in the chipping code the less likely it will be that the original data will be lost. This is the most commonly used among Spread Spectrum technology. To an unintended receiver, DSSS appears as low-power wideband noise and is rejected (ignored) by most narrowband receivers.

Infrared (IR) systems are another option to the available technologies for wireless LANs. 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; it is either directed (line-of-sight) or diffuse technology. Inexpensive directed systems provide very limited range (3 ft) and typically are used for PANs but occasionally are used in specific WLAN applications. High performance directed IR is impractical for mobile users and is therefore used only to implement fixed subnetworks. Diffuse (or reflective) IR WLAN systems do not require line-of-sight, but cells are limited to individual rooms.

The IEEE 802.11 defines physical layer options for wireless transmission and MAC layer protocol.The IEEE 802.11 represents the first standard for WLAN products from an internationally recognized, independent organization. The IEEE manages most of the standards for wired LANs. It represents an important milestone in WLAN systems since customers can now have multiple sources for the components of their WLAN systems. There are still applications where the existing proprietary data communications are a good fit because they may optimize some aspect of the network performance. However, 802.11 compliant products expand the users' options.

The majority of the WLAN products available in the marketplace today are proprietary spread spectrum solutions targeting vertical applications operating in the 900MHz and 2.4GHz ISM frequency bands. These products include wireless adapters and access points in PCMCIA, ISA and custom PC board platforms. Proprietary solutions for some applications are beneficial, especially for those requiring market differentiation or customization of a wireless LAN network. Proprietary solutions are typically customized and constrain the end users into purchasing products from a single equipment supplier. However, as products are introduced compliant to the standard, users can choose from a number of vendors that provide compatible products. This increases competition and provides the potential for lower cost products.

The Standards Committee

The IEEE 802 standards committee formed the 802.11 Wireless Local Area Networks Standards Working Group in 1990. The 802.11 working group took on the task of developing a global standard for radio equipment and networks operating in the 2.4GHz unlicensed

frequency band for data rates of 1 and 2Mbps. The 802.11 working group has recently completed the standard. The standard does not specify technology or implementation but simply specifications for the physical layer and Media Access Control (MAC) layer. The standard allows for manufacturers of wireless LAN radio equipment to build interoperable network equipment.

The membership of the committee consists of individuals from a number of companies and universities, who research, manufacturer, install and use products in wireless LAN network applications. Manufacturers of semiconductors, computers, radio equipment, WLAN systems solution providers, University research labs and end-users make up the core group. The working group is globally represented by companies from the United States, Canada, Europe, Israel and the Pacific Rim.

Physical Layer Implementation Choices

The Physical Layer in any network defines the modulation and signaling characteristics for the transmission of data. At the physical layer, two RF transmission methods and one infrared are defined. Operation of the WLAN in unlicensed RF bands requires the of spread spectrum modulation to meet the requirements for operation in most countries. The RF transmission standards in the standard are Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS). Both architectures are defined for operation in the 2.4GHz frequency band typically occupying the 83 MHz of bandwidth from 2.400 GHz to 2.483 GHz. Differential BPSK (DBPSK) and DQPSK is the modulation for the direct sequence. Frequency hopping uses 2-4 level Gaussian FSK as the modulation signaling method. The radiated RF power at the antenna is set by the rules governed by FCC part 15 for operation in the United States. Antenna gain is also limited to 6 dBi maximum. The radiated power is limited to 1W for the United States, 10mW per 1Mhz in Europe and 10mW for Japan. There are different frequencies approved for use in Japan, United States and Europe and any WLAN product must meet the requirements for the country where it is sold. See the appendix for details of the different frequency allocations for unlicensed operation in US, Europe and Japan. The physical layer data rate for FHSS system is 1 Mbps. For DSSS both 1 Mbps and 2 Mbps data rates are supported. The choice between FHSS and DSSS will depend on a number of factors related to the user application and the environment that the system will be operating.

Infra-Red Physical Layer

One infrared standard is supported which operates in the 850-to-950nM band with peak power of 2 W. The modulation for infrared is accomplished using either 4 or 16-level pulse-positioning modulation. The physical layer supports two data rates, 1 and 2Mbps.

Direct Sequencing Spread Spectrum (DSSS) Physical Layer

The DSSS physical layer uses an 11-bit Barker Sequence to spread the data before it is transmitted. Each bit transmitted is modulated by the 11-bit sequence. This process spreads the RF energy across a wider bandwidth than would be required to transmit the raw data. The processing gain of the system is defined as 10x the log of the ratio of spreading rate (also know as the chip rate) to the data. The receiver despreads the RF input to recover the original data. The advantage of this technique is that it reduces the effect of narrowband sources of interference. This sequence provides 10.4dB of processing gain which meets the minimum requirements for the rules set forth by the FCC. The spreading architecture used in the direct sequence physical layer is not to be confused with CDMA. All 802.11 compliant products utilize the same PN code and therefore do not have a set of codes available as is required for CDMA operation.

Frequency Hopping Spread Spectrum (FHSS) Physical Layer

The FHSS physical layer has 22 hop patterns to choose from. The frequency hop physical layer is required to hop across the 2.4GHz ISM band covering 79 channels. Each channel occupies 1Mhz of bandwidth and must hop at the minimum rate specified by the regulatory bodies of the intended country. A minimum hop rate of 2.5 hops per second is specified for the United States.

Each of the physical layers use their own unique header to synchronize the receiver and to determine signal modulation format.

The MAC Layer

The MAC layer specification for 802.11 has similarities to the 802.3 Ethernet wired line standard. The protocol for 802.11 uses a protocol scheme know as carrier-sense, multiple access, collision avoidance (CSMA/CA). This protocol avoids collisions instead of detecting a collision like the algorithm used in 802.3. It is difficult to detect collisions in a RF transmission network and it is for this reason that collision avoidance is used. The MAC layer operates together with the physical layer by sampling the energy over the medium transmitting data. The physical layer uses a clear channel assessment (CCA) algorithm to determine if the channel is clear. This is accomplished by measuring the RF energy at the antenna and determining the strength of the received signal. This measured signal is commonly known as RSSI. If the received signal strength is below a specified threshold the channel is declared clear and the MAC layer is given the clear channel status for data transmission. If the RF energy is above the threshold, data transmissions are deferred in accordance with the protocol rules. The standard provides another option for CCA that can be alone or with the RSSI measurement. Carrier sense can be used to determine if the channel is available. This technique is more selective sense since it verifies that the signal is the same carrier type as 802.11 transmitters. The best method to use depends upon the levels of interference in the operating environment. The CSMA/CA protocol allows for options the can minimize collisions by using request to send (RTS), clear-to-send (CTS), data and acknowledge (ACK) transmission frames, in a sequential fashion. Communications is established when one of the wireless nodes sends a short message RTS frame. The RTS frame includes the destination and the length of message. The message duration is known as the network allocation vector (NAV). The NAV alerts all others in the medium, to back off for the duration of the transmission. The receiving station issues a CTS frame which echoes the sender's address and the NAV. If the CTS frame is not received, it is assumed that a collision occurred and the RTS process starts over. After the data frame is received, an ACK frame is sent back verifying a successful data transmission. A common limitation with wireless LAN systems is the "hidden node" problem. This can disrupt 40% or more of the communications in a highly loaded LAN environment. It occurs when there is a station in a service set that cannot detect the transmission of another station to detect that the media is busy. In figure 1 stations A and B can communicate. However an obstruction prevents station C from receiving station A and it cannot determine when the channel is busy. Therefore both stations A and C could try to transmit at the same time to station B. The use of RTS, CTS, Data and ACK sequences helps the prevent the disruptions caused by this problem.

Security provisions are addressed in the standard as an optional feature for those concerned about eaves dropping. The data security is accomplished by a complex encryption technique know as the Wired Equivalent Privacy Algorithm (WEP). WEP is based on protecting the transmitted data over the RF medium using a 64-bit seed key and the RC4 encryption algorithm. WEP, when enabled, only protects the data packet information and does not protect the physical layer header so that other stations on the network can listen to the control data needed to manage the network. However, the other stations cannot decrypt the data portions of the packet.

Power management is supported at the MAC level for those applications requiring mobility under battery operation. Provisions are made in the protocol for the portable stations to go to low power "sleep" mode during a time interval defined by the base station.

data packet length. The physical layer headers are always transmitted at 1Mbps. Predefined fields in the headers provide the option to increase the data rate to 2 Mbps for the actual data packet

IEEE 802.11 Future Development
A new specification has been proposed called Internet-Access Point Protocol (IAPP). This is intended to go beyond the work that has been done by the IEEE 802.11 at the MAC and PHY (physical-layer specification) layers. This new proposed standard works at higher OSI (Open Systems Interconnection) layers to establish the way access points communicate across cells in the wired backbone. This new proposal is backed by Aironet, Lucent Technologies, and Digital Ocean Inc.

Wireless LANs are making inroads in plathora of applications and making networking experince mobile and dynamic.

Wireless LANs in Your Industry
Below are listed some of the ubiquotous examples, the list is sure to grow by leaps and bounds in years to come!

• Corporate
  With a wireless LAN, corporate employees can take advantage of
  mobile networking for e-mail, file sharing, and web browsing
  regardless of where they are in the office.

• Education
  Academic institutions leverage the benefits of mobile connectivity
  be enabling users with notebook computers to connect to the
  university network for collaborative class discussions and to the
  Internet for e-mail and web browsing.
• Finance
  By carrying a handheld PC with a wireless LAN adapter, financial
  traders can receive pricing information from a database in real-time
  and improve the speed and quality of trades. Accounting audit teams increase productivity with quick network setup.
• Healthcare
  Using wireless handheld computers to access real-time information,
  healthcare providers increase productivity and quality of patient care
  by eliminating patient treatment delays, redundant paperwork,
  potential transcription errors, and billing cycle delays.
• Hospitality and Retail
  Hospitality services can use wireless LANs to directly enter and
  send food orders from the table. Retail stores can use wireless
  LANs to set up temporary registers for special events.
• Manufacturing
  Wireless networking helps link factory floor workstations and data
  collection devices to a company's network.
• Warehousing
  In warehouses, handheld and forklift-mounted data terminals with
  barcode readers and wireless data links are used to enter and
  maintain the location of pallets and boxes. Wireless improves
  inventory tracking and reduces the costs of physical inventory
  counts.

In conclusion we see that wireless LAN can be very usefull and is still only in a developmental stage. To connect to a traditional wired LAN a user must plug his or her computer into a wall or a floor LAN outlet. Wireless LANs' portability and compatibility with all operating systems make it an ideal choice for office intranets. We believe that with the new standard 802.11 that is being introduced by IEEE more control will be available over wireless infrastructures, and more and more wireless LANs will start blossoming in many offices.