Wireless Local Area Networks

Wireless Local Area Networks

The establishment of home and business networks desirous of upgrading to Wireless Local Area Network- WLAN confront with the problems of choosing from available alternatives. The vendors offer several products for sale that hovers around different wireless standards like 802.11a, 802.11b, 802.11g and Bluetooth. During the year 1997, the Institute of Electrical and Electronics Engineers -- IEEE developed the first WLAN standard. They termed it 802.11 in line with the name given to the group appointed for supervising its development. However, to our misfortune the 802.11 could support only a maximum bandwidth of 2 Mbps -- too slow for most applications. Due to these ordinary 802.11 wireless products could not be manufactured further. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?)

The IEEE standard is an extension of the original 802.11 standard devised during July, 1999 generating 802.11b specification. While 802.11b was devised the IEEE generated a second extension to the original 802.11 standard regarded as 802.11a. Since the 802.11b was become much popular and become much faster than 802.11a, some took it for granted that 802.11a was devised only after the 802.11b. However, in reality the 802.11a was developed at a similar period. As a result of its higher costs, 802.11a was adopted widely in the business market while the 802.11b provided better services at the home market. During the period 2002 and 2003, the WLAN products supporting a new standard known as 802.11g started emerge in the scenario. The Bluetooth emerged to be an alternative wireless network technology that went through different developmental path in comparison to the 802.11 family. So as to make an educated network building decision, one is required to be aware of the comparative pros and cons of each of such technologies. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?) This paper shall thus deal with a comparison of the standards of 802.11a, 802.11b, 802.11g and Bluetooth, analyzing each of their merits and demerits and arrive at a conclusion as to which is the best technology.

Discussion:

The mobile users enabled to receive Ethernet levels of performance, throughput, and availability with the application of 802.11b WLANs. The fundamental features, designing and services of 802.11b are indicated to be the original 802.11 standard. The original 802.11 DSSS standard spells out an 11-bit chipping called a Barker sequence to code all the transmitted data over the air. Each of the 11-chip sequence indicates a single data bit which is 1 or 0, and is transformed to a waveform known as a symbol that can be sent over the air. Such symbols are sent at a speed of 1 MSps or 1 million symbols per second in terms of the symbol rate measured through the technique of Binary Phase Shift Keying -- BPSK. In case of 2 Mbps, a more refined implementation known as Quadrature Phase Shift Keying -- QPSK is applied; it enhances the data rate available in BPSK to the extent of almost double through the developed efficiency in the utilization of bandwidth. (Wireless LAN (Wifi) Tutorial)

To enhance the data rate in the 802.11b standard, advanced coding techniques are employed. The 802.11b specification influences only the physical layer, supplementing higher data rates and more strong connectivity. The crucial involvement of the 802.11b supplementation to the wireless LAN standard was to regulate the physical layer support of two new speeds 5.5 Mbps and 11 Mbps. To attain this DSSS was required to be chosen as the sole physical layer technique for the standard since, as the frequency leaping cannot safeguard the higher speeds without violating current FCC stipulations. The implication is that 802.11b systems will operate internally along with the 1 Mbps and 2 Mbps 802.11 FHSS systems. (Wireless LAN (Wifi) Tutorial)

IEEE 802.11b transmits data at 1, 2, 5.5 or 11 Megabits per second -- Mbps applying the 2.4-2.5 gigahertz -- GHz S-Band Industrial, Scientific, and Medical -- ISM frequency range. To attain optimum conditions the close proximity and no sources of attenuation or interference, IEEE 802.11b seems to operate at 11 Mbps, considered to be of higher bit rate in comparison to the 10 Mbps wired Ethernet. In less than optimal conditions the slower speeds of 5.5 Mbps, 2 Mbps, and 1 Mbps are used. The 802.11b applies the same radio signaling frequency -- 2.4 GHz -- as the original 802.11 standard. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?) Its operation is comparable with 802.11a and necessitates fewer access points than 802.11a for exposure of large areas. It offers high-speed access to data up to 300 feet from the base station and 14 channels are available in the 2.4GHz band with only three non-overlapping channels. (Wireless LAN Standards) The Vendors some time select application of uncontrolled frequencies to reduce their production costs. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?)

The 802.11b standard in wireless technology was regarded as the most crucial wave to hit large in wireless development which is in major part to Lucent and Apple's adoption. Lucent and Apple developed 802.11b base stations or access points based on a reference design by AMD during 1999. Ever since that moment the adoption has been extensive. The wireless bases have been installed all over, ranging from corporate environments to homes to coffee shops. Now, we all understand that 802.11b is applicable in the 2.4 GHz range simultaneously with cordless phones, microwaves, and Bluetooth. Prior to a couple of years when people started to looking forward to 'the Next Big Thing' we turned to 802.11a as the path forward. (The 802.11g standard -- IEEE) One of the prominent drawbacks of 802.11b is that the frequency band is crowded and subject to interference from other networking technologies, microwave ovens, 2.4 GHz cordless phones and Bluetooth. The weaknesses of 802.11b include lack of compatibility with voice devices and no QoS provisions for multimedia content. (Wireless LAN (Wifi) Tutorial) Being an uncontrolled frequency, 802.11b gear can incur interference from microwave ovens, cordless phones, and other appliances operating in the similar 2.4 GHz range. However, by installing 802.11b gear a normal differentiation from other appliances, interference can easily be avoided. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?)

The IEEE 802.11a standard has an optimum bit rate of about 54 Mbps and applies frequencies in the 5 GHz range incorporating the 5.725-5.875 GHz C-Band ISM frequency band. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?) The 802.11a applied Orthogonal Frequency Division Multiplexing -- OFDM, an emerging encoding scheme that extends advantages over the extension of channel availability and data rate. Channel availability is important since the more independent are the available channels the more scalable the wireless network becomes. The 802.11a involves the application of OFDM to indicate a total of 8 non-overlapping 20 MHz channels over the 2 lower bands. Comparatively, 802.11b applies 3 non-overlapping channels. (Wireless LAN (Wifi) Tutorial)

The advantages of 802.11a are fastest maximum speed, supports more simultaneous users; controlled frequency avoids signal interference from other devices. The Higher and more data rates are not the only benefit 802.11a's. It also utilizes the higher frequency band, 5 GHz, which is both wider and less crowded than the 2.4 GHz band that 802.11b shares with cordless phones, microwave ovens, and Bluetooth devices. (Wireless LAN (Wifi) Tutorial) The enhanced speed technology permits the wireless LAN networking to ensure better performance in respect of the video and conferencing applications. Since they are not on the same frequencies as Bluetooth or microwave ovens, IEEE 802.11a entails both a higher data rate and a cleaner signal. (Configuring Windows XP IEEE 802.11 Wireless Networks for the Home and Small Business) It is better than 802.11b at sustaining multimedia voice, video and large-image applications in densely populated user environments. (Wireless LAN Standards)

The disadvantages of 802.11a involve highest costs simultaneously having shorter range signal that is more prominently obstructed. It is less potential for RF interference than 802.11b and 802.11g. It is comparatively of low range than 802.11b and is not compatible with 802.11b. (Wireless LAN Standards) Compared to 802.11b, this enhanced frequency confines the range of 802.11a. The higher frequency also implies 802.11a signals those have more problems piercing walls and other obstructions. Since 802.11a signals apply different frequencies, the two technologies re not compatible with each other and entail new bridging products that can support both types of networks. Some vendors offer hybrid 802.11a/b network gear since such products simply entail the two standards simultaneously. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?) The explanation for 802.11a so as to be compatible to the abilities of 802.11g is for manufacturers to generate client and access point equipment involving 802.11a and 802.11b. In absence of its cost effectiveness and competitive price or of greater usability range it is not possible to visualize as to how it could succeed in the market. This hypothesis is exploited to take the most out of this technology 802.11a visualized to be a certainty. (The 802.11g standard -- IEEE)

Irrespective of the fact that 5 GHz has many benefits it also has several inherent difficulties. The most significant of these is compatibility: The different frequencies imply that 802.11a-based devices are not compatible with 802.11b base. To overcome this the IEEE devised 802.11g that is required to extend the speed and range of 802.11b so as to ensure its fully compatibility with the older systems. The standard functions entirely in the 2.4 GHz frequency but applies a minimum of two modes which are both compulsory with two optional modes. The mandatory modulation/access modes are the similar CCK -- Complementary Code Keying mode applied in 802.11b applications therefore, ensure compatibility and the OFDM or Orthogonal Frequency Division Multiplexing mode applied in 802.11a however, in this case only in the 2.4 GHz frequency band. (Wireless LAN (Wifi) Tutorial)

The compulsory CCK form supports 11 Mpbs and the OFDM form has a highest of 54 Mbps.Two forms are present which employs various means to achieve a 22 Mbps data rates PBCC-22 -- Packet Binary Convolutional Coding, graded for 6 to 54 Mbps and CCK-OFDM form having a graded maximum of 33 Mbps. (Wireless LAN (Wifi) Tutorial) Besides 802.11g widens the OSI Model Physical Layer -- PHY of 802.211b from 11 Mbps employing DSSS modulation to 54 Mbps employing OFDM modulation. (802.11g Approved by IEEE Working Group) The IEEE 802.1g norm possess a topmost bit rate if 54 Mbps and employs the S-Band ISM. (Configuring Windows XP IEEE 802.11 Wireless Networks for the Home and Small Business) The accessibility of channels in the 2.4 GHz band is 14 with non-overlapping channels being limited to just three. As compared to 802.11, this is more secured. 802.11g tries to blend the best feature of 802.11a as well as 802.11b. (Wireless LAN Standards) The evident benefit of 802.11g is that it keeps up consistency with the 802.11b and also gives speedier data transmission rates analogous with 802.11a. (Wireless LAN (Wifi) Tutorial)

802.11g works with and utilizes the 2.4 GHz frequency for broader range. To mean that 802.11g maintains backward compatibility with 802.11b, it implies that 802.11g access points will operate with 802.11b wireless network adaptors and the reverse is also true. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?) The arguments in favor of 802.11g are that it possess the greatest top speed; is able to take more users who are using it all at the same time; the signal range is the most excellent and does not get intercepted so easily. 802.11g is a trouble-free choice for corporate sites as well as home users to assume as it doesn't need an improvement to equipment of client. Those who use 802.11g will be enjoying backward compatibility with the present deployed base of 802.11b products, though at 802.11b's sluggish data rate. (802.11g Approved by IEEE Working Group) The downside of 802.11g is that the expenses are higher compared to 802.11b and equipments might suffer interference on the unsynchronized signal frequency. (802.11 Standards - 802.11b 802.11a 802.11g: Which one is right for You?) A last demerit of 802.11g is that is even functions in the 2.4GHz band and as such because of interference it is not going to be as rapid as 802.11a. (Wireless LAN (Wifi) Tutorial)

Bluetooth

A very recent technology norm employing short-range radio linkages is known as Bluetooth, with the objective of replacing the wires linking the portable and/or fixed electronic gadgets. (Wireless LAN (Wifi) Tutorial) The norm describes a homogenous structure for a broad assortment of equipments for inter-communications with the least effort by the user. The important characteristics are strength, simplicity, energy efficient, and cost effectiveness. The technology also gives wireless access to LAN, PSTN, the cellular telephone network and the Internet for a lot of domestic appliances and also portable handheld interfaces. The urgent necessity for Bluetooth emanated from the yearning to link peripherals and gadgets without wires. The existent technology IrDA OBEX -- IR Data Association Object Exchange Protocol is set up in IR connections, which are restricted to connections in a straight manner. Bluetooth integration is more instigated by the want for mobile and wireless access to LANs, access to Internet through the mobile network and other available networks in which case the main structure is linked through wires; however the interface has a freedom of movement. Through this arrangement, the network becomes hassle free for use as also the range is expanded. (Wireless LAN (Wifi) Tutorial)