WIRELESS LAN
Introduction
Maintain a constant affiliation hard-to-reach
This paper is about the emerging technology of Wireless LANs that are being used in many businesses today. A historical overview will start the discussion as it moves on to the discussion of its application and technology. Wireless LANs will be defined and describes in details in the following sections.
Historical Overview
They say that back in 1971, at the University of Hawaii, researchers developed ALOHAnet, the world’s first ever wireless local area network. The system was a bi-directional star topology that included seven computers. These computers were deployed over four islands. The central computer was deployed at Oahu island without using any phone lines.
Back then, wireless LAN hardware were so expensive. Due to this, WLAN was only used as an alternative for cabled LAN. Ultimately, it was used for places that were only difficult or impossible for cabling.
Moreover, according to Wikipedia, “early innovations included industry-specified solutions and propriety protocols.” But as 1990s ended, these solutions and protocols were swapped by standards, mainly the many diversified versions of IEEE 8012.11 (Wi-Fi). There has been an alternative developed like the ATM-like HIPERLAN. But it did not succeed in the market. Apparently, it never will, especially when the faster 54 Mbit/s 802.111 (5 GHz) and 802.11g (2.4GHz) standards were released.
As of last year, The Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) have been in battle with other software and hardware giants for royalties on the patents that are allegedly held by CSIRO regarding these technologies. CSIRO claims to have been the first to develop wireless networking.
Application/Technology
Wireless networks include several technologies, each with its own optimal use. Wireless LAN technology, mainly the 802.11 set of standards, helps create wireless networks similar to organization-wired Ethernet networks.
Wireless LANs also can provide a cost benefit. Installing and configuring wired communications can be costly, especially in those hard-to-reach areas. Ladders, drop ceilings, heavy furniture, kneepads, and a lot of time are often necessary to get all components installed and connected properly. By comparison, wireless LAN installations are a breeze. Plug in the access point, install a wireless network interface card (NIC), and you are all set.
An access point is the device that acts as a gateway for wireless devices (Andress, 2003). Through this gateway, wireless devices access the network, as shown in Figure 1.
Stations – are referred to as all components that can connect into wireless medium in a network. All stations have wireless network interface cards (WNICS). Wireless stations fall into one of two categories: access points and clients.
Clients – can be mobile devices such as personal digital assistants (PDAs), laptops, fixed devices such as desktops and workstations, or IP phones. All which are equipped with WNICs.
Basic service set – or BSS is a set of all stations who communicate with each other. Two types of BSS are: infrastructure BSS and independent BSS. BSS has an identification called the BSID. The BSID is the MAC address of the access point in service of BSS.
Extended service set – or ESS is a set of all connected BSSes. ESS also has an identification called the SSID. The SSID is a 32-byte (maximum) character string. All access points in an ESS are connected by a distribution system.
Distribution system – as mentioned above, the distribution system connects all access points in an ESS. Usually, a distribution system is a wired LAN but can also be a wireless LAN.
What Is It, Including Technology Overview
A wireless local area network (WLAN) is said to be a set of network components. These network components are connected by electromagnetic (radio) waves instead of the more commonly used wires. WLANs are used as a substitute for wired computer networks. It adds freedom of movement and flexibility within the workplace. Oftentimes, it is also used in combination with wired computer networks. Clients who use WLANs enjoy the easy access on their respective company networks and even the Internet from almost anywhere within and throughout the boardroom, campus or store. They do this without relying on any wired cables and connections available.
There are two modes that the proposed standard 802.11 works on: (1) in the absence of base station and, (2) in the presence of base station. In the first case, computers that communicate with each other through this mode is called ad hoc networking. The latter case on the other hand is called the infrastructure mode. All communication goes through the base station, which is the access point in 802.11 terminologies.
IEEE (working committee) 802.11 indicates set of wireless WLAN/LAN standards. Some challenges that they met as they developed these standards were: “dealing with the fact that radio signals have a finite range; building a system with enough bandwidth to be economically feasible; ensuring users privacy and security; finding a suitable frequency band that was available, preferably worldwide; and finally, worrying about human safety.”
During the standardization process, 802.11 was decided to be made compatible with Ethernet above data link layer. Inherent differences existed eventually which had to be taken care of by the standard.
Foremost, before transmitting, a computer on Ethernet always listens to the ether. This is not possible in case of WLANs. Collision may take place as the range of a station may not be able to detect transmission that is taking place between two other stations.
Another problem that were to be solved was the interference resulting in what we call Multipath fading. This was a result of radio signals being received a multiple times because they can be reflected off solid objects.
The last dilemma was is a notebook computer were to be moved away from the base station to another, a way of handing it off must be done.
Eventually, the committee came up with a standard to finally address these concerns. The amendment 802.11i also enhanced the security. Among the most popular of amendments are 802.11a, 802.11b and 802.11g to original standard. Service enhancements and extensions are in other specifications from (c-f, h, j).
Who Does/Might Use It
Basically almost every establishment and organization that is spread over an area uses WAN. WLAN however are more for the persons on the go.
Outline of Development/Uptake Challenges
Before we move on, let us discuss the standards that are the basis for communication. In June 1997, the IEEE (Institute of Electrical and Electronics Engineers) finalized IEEE 802.11, the initial standard for wireless LANs. This standard specifies a 2.4GHz operating frequency with data rates of 1Mbps to 2Mbps and the capability to choose between using frequency hopping or using direct sequence, two incompatible forms of spread-spectrum modulation. In late 1999, the IEEE published two supplements to the initial 802.11 standard: 802.11a and 802.11b.
Like the initial standard, 802.11b operates in the 2.4GHz band, but data rates can be as high as 11Mbps, and only direct-sequence modulation is specified. The 802.1 la standard specifies operation in the 5GHz band using orthogonal frequency division multiplexing (OFDM) with data rates up to 54Mbps. The advantages of this standard include higher capacity and less radio frequency (RF) interference than with other types of devices.
802.1 la and 802.11b operate in different frequencies, so they are not interoperable. They can coexist on one network, though, because no signal overlap exists. Some vendors provide a dual-radio system with 802.11a and 802.11b.
The latest wireless standard is 802.11g, and (like 802.1 la) it provides data rates of 54Mbps, but (like 802.11b) it operates in the 2.4GHz range. The 802.11g standard is also backward compatible with 802.11b networks, providing a more cost-effective upgrade and rollout plan for organizations.
To complicate issues, Europe has developed the HiperLAN/2 standard, led by the European Telecommunications Standards Institute (ETSI). HiperLAN/2 and 802.1 la share some similarities: both use OFDM technology to achieve their data rates in the 5GHz range, but they are not interoperable.
Anyway, before the discussion goes further, the approval of the initial IEEE 802.11 standard back in 1997 spurred rapid growth in WLANs beyond the traditional, low-bandwidth vertical applications and into mission-critical general-office applications. In September 1999, however, 11-Mbps 802.11b standard was approved and the horizontal WLAN market achieved some impression of legitimacy, followed by rapid acceleration.
Analysts have long anticipated the fever that surrounded WLAN. Yet with the success, according to Mathias (2003), WLANs are still not immune to the rip currents that pervade essentially ever high-technology market. He states the following observations:
(a) There is a constant demand in price and performance. (b) There is a need to deal with rapid technological change and continuing 802.11 evolutions. (c) Security. And, (d) there is a requirement to lower operational and other recurring expenses.
It comes as no surprise, then, that wireless-LAN vendors have been sparing little effort in building additional tools and now entirely new architectures to address the above needs. The primary goals today are to improve manageability, security and the costs of both equipment and operations. In short, what we are seeing is the result of a very natural evolutionary process, which is endemic to high technology.
Current Technical/Business Status (where relevant)
Wexler (2006) observed that the subject of 802.11 has created a controversy during the past year. Choices of controversy from whether municipalities which organize mesh networks have advantage over competing service providers, which are to them is unfair, to whether strangers who take undue credit on unsecured networks at home are assisting terrorists.
However, although WiFi has been phenomenal, market analysts feel a recognizable stillness before the storm. Wexler states the following reasons:
(a) The current Wi-Fi base installed includes the older Aironet equipment of Cisco Systems. This equipment has individually managed, intelligent access points (APs) which are also called “traditional” or “thick” APs. A majority of the customers using these systems are just starting to learn the newer, centrally run (“thin” or “dependent”) APs, and the supplementary changed Wi-Fi architecture.
(b) Dual-mode handsets that support both Wi-Fi and cellular voice calls before they make commitments to deploying voice over IP (VOIP) over Wi-Fi networks have been waited by mainstream enterprises.
(c) Recognized enterprise WLAN services are still catching up to technology advances of Wi-Fi, mainly in the security area.
(2006) explains that despite the continuous development in the standards and product features, especially in the area of detecting intruders and prevention, that the WiFi industry makes, projects “can only move so fast”. She says that the mobility in wireless services have always been a must. This need for wireless mobility have set up trends in accordance to the voice over Wi-Fi. On the contrary, there has been sprouting security measures with regards to this uprising technology. Thereby, it makes it difficult for some to even avail of the said services. This is most accordingly hard for client with small handheld devices. All because of 802.11. There are no supplicants available for them yet.
She explains further that time will tell before masses who currently use Cisco customary dispersed APs go along with the trends, although the direction of Wi-Fi provisioning, administration and RF management is toward centralization. Also, she sees that not until devices that are converged supporting both cellular voice capabilities and Wi-Fi are available widely, mainstream enterprises will seem to be putting off huge promises to voice over Wi-Fi.
Moreover, (2006) says the general enterprise WLAN is in a bit being held until full 802.11e QOS-enabled implementations are available and Wi-Fi-certified, dual-mode phones are available in the market, deployment issues and interoperability associated with 802.11i security components get cleared up. It also becomes obvious if 802.11a is going to be a real network player ever, or will just be leapfrogged by 802.11n.
Technical Details In Depth Explaining Total Value Chain
Benefits of wireless LANs include:
Convenience
The particular benefit is relevant as there has been an increase in the use of laptops. Such networks whose wireless nature makes it easy for users at office or at home access network resources. Basically almost any location that is convenient within any an environment of networking that is primary.
Mobility
There has been an emerging business in wireless networks in public internet cafes. Users may have access to the internet through this publiclly accessed networks. Nowadayas, many coffee shops-chain, offer customers with internet connection at a small or no cost.
Productivity
Users who are out from work could still connect to a wireless network. This way, they can maintain a mainly constant association with the network they wanted even though they are moving from one place to another. An employee could still do his work even though he is not physically present at work.
Deployment
Wired networks are more costly and complex of real physical cables that are connected to various areas. Sometimes, these places could even be remote areas or are even impossible to reach. Wireless networks however, need little more than a single access point during Initial setup.
Expandability
Wired networks need additional wiring in case there is a sudden increase in clients. With a wireless network however, a sudden increase in the number of client could be served with the existing equipment.
Cost
Needless to saym wired and wireless networks alike are both costly. However, weighing the circumstances or other benefits onme would get from a wireless network, additional cost is as justifiable compared to physical components from a wired network.
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Disadvantages on the other hand include: additional
Security
Radio frequencies are used by WLAN transceivers to serve computers in a network with undisturbed service. Actually, antennas that are there on wireless networking cards are nothing. It actually is more naive than most of receiving units. To correctly obtain signals using antennas, WLAN transceiver utilizes generous amount of power. This means that wireless packets can be disturbed and accessed by a nearby computer, and that a user could receive packets at a distance; maybe many times the radius as the usual user. There are wardrivers who dedicate themselves to locate and even hack wireless networks. With wireless packets, no one has to beat the physical restriction of tapping the wires. To fight this dilemma, wireless networks will have to use other encryption technolog in the market. However, there are encryption methods that have weaknesses only a dedicated enemy can compromise.
Range
An ordinary 802.11g network has a typical range of many meters. That order is, if it has standard equipment. This is appropriate for home, but how about in the office? Added access points or repeaters has to be purchased to obtain additional ranges. These items may add up in costs quickly. Fortunately, some items are being developed to void this disadvantage.
Reliability
The network administrator has little control for some inteferences that happens in a wireless network. These includes complicated propagation effects in this case, especially the Rician fading or multipath. Modulation is achieved in typical networks through complicated forms of quadrature amplitude modulation (QAM) or phase-shift keying (PSK). This makes more disturbing propagation effects and interference. Because of this, network resources that are important such as servers are connected wirelessl rarely.
Speed
Ordinary wired networks are even faster than most wireless networks. Its built-in congestion avoidance and TCP also causes some performance issues. But with most users, this is not important because the speed bottleneck is outside network connectivity itself and not within the wireless routing. For example, telecommunications companies that offer maximum ADSL services for their general-purpose customers is slower than the slowest wireless network. This is in which the network is typically connected. That means, in many environments, a wireless network that runs at its slowest is actually faster than internet connection that serves it. In special environments on the other hand, the throughput of a wired network is necessary.
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Any Other Relevant Topics
(2004) seems to agree that WLANs still needs improvement. She states that:
“WLAN adopters are clearly committed to the technology, as evidenced by their plans to deploy to more end users and to add functionality. But what about the suppliers? Will the areas that need improvement be addressed?
There is plenty of reason to conclude that the answer is yes. Products from wireless specialist companies like Reefedge and Trapeze Networks are aimed at helping enterprises design and manage increasingly complex WLAN deployments, while industry leaders like Cisco and 3Com continue to introduce enhancements to their products. Since so many industry players see wireless as one of the few shining spots in the industry, you can be certain that R & D investments will continue.”
Credit:ivythesis.typepad.com
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