Wireless Networks

Wireless LANs (WLANs) enable users to establish and maintain a wireless network connection throughout or between buildings, without the limitations of wires or cables. Using radio frequency technology, WLANs increase productivity among mobile employees through network access to email, the Internet, or corporate networks. In-the-office productivity is available anywhere the worker has WLAN access, such as a corporate building or campus, in airports, hotels, or other public wireless “hot” spots.

WLANs also offer users increased bandwidth with no recurring costs, which most often results in a solid return on investment within 12-18 months. Diltronix ’s networking engineers can assist you in determining if a WLAN is the right technology to move your business ahead.

Wireless Network standards

1 . 802.11a Wireless LAN
The first wireless LAN (WLAN) standard was created by the IEEE committee in 1997, and was called 802.11. However, 802.11 standard supported only up to 2 Mbps of bandwidth, and quickly became obsolete. Subsequently, IEEE created the 802.11a, and 802.11b standards. The following are the advantages of the IEEE 802.11a standard compared to 802.11b:

• 802.11a uses 5GHz frequency band which is less crowded and hence has relatively smaller interference problem.
• 802.11a supports up to 54Mbps of bandwidth, which is much faster than the 11Mbps bandwidth provided by 802.11b standard devices.
• 802.11a offers as many as 12 non-overlapping channels. With more channels, larger number of users can be accommodated with no performance degradation.

Some of the disadvantages of using the 802.11a standard are:

• Not many client devices such as note book computers, PDAs support 802.11a standard. Most of these support either 802.11b or Bluetooth standards.
• It is more expensive compared to other contemporary technologies like 802.11b and Bluetooth.
• 802.11a standards are not compatible with 802.11b. Hence, devices manufactured complying with 802.11a and 802.11b respectively, are not interoperable.
• The distance covered will be slightly less compared to 802.11b due to higher operating frequency (5 GHz). Note that, higher the radio frequency, lower the propagation distance for a given output power.

You may consider using 802.11g in place of 802.11a for reasons of cross compatibility.

2 . 802.11b Wireless LAN (Also known as Wi-Fi)
The following are the advantages of the IEEE 802.11b standard compared to 802.11a and Bluetooth wireless LAN :

• The 802.11b WLAN standard is widely supported by manufacturers, and very cost effective.
• Easy to set-up and maintain.
• Suits well for home segment due to lower costs and simple set-up.

The following are some of the disadvantages:

• Supports only up to 11Mbps bandwidth. Though the speed is sufficient for most applications, it limits the number of simultaneous users to a far less number compared to 802.11a.
• It operates in 2.4GHz frequency band, which is normally used by many appliances. Hence, it is more interference prone compared to 802.11a.
• Doesn't provide suitable scalability required in business environment.
  

3. 802.11g Wireless LAN
The IEEE's 802.11g standard is a higher-bandwidth successor to the popular 802.11b, or Wi-Fi standard. 802.11g operates at a maximum speed of 54Mbps whereas 802.11b has a maximum speed of 11Mbps (Megabits/sec). An 802.11g access point compatible with both 802.11b and 802.11g clients. As a result, a laptop computer with an 802.11g card will be able to access existing 802.11b access points as well as new 802.11g access points.
The following are the main advantages of 802.11g over 802.11b:

• Higher bandwidth at 54 Mbps
• Cheaper than 802.11a, and costs close to 802.11b. 802.11g uses 2.4GHz frequency band, just like 802.11b.
• Backward compatible with 802.11b standard
  

The main disadvantages are:

• Higher cost compared to 802.11b (at least by 50%)
• Not yet widely supported by the client machines such as laptops, and PDAs.

Consider the availability of dual band devices while making any procurements. Devices compatible with both 802.11a and 802.11g (inherently compatible with 802.11b) are a good buy considering future expansion and compatibility in diverse network environments.

4. Wireless LANs: Bluetooth
Bluetooth is an alternative wireless network technology that followed a different development path than the 802.11 family of standards. Bluetooth offers more flexibility than 802.11b but on a smaller range and speed. Its bandwidth is only 500Kbps, and its range is only 10 meters (30 feet). Devices with a Bluetooth radio and an antenna can speak to each other with little or no preparation. For example, conference attendees can readily transfer files across a table using their Bluetooth-enabled notebooks. You can also send a file to a Bluetooth-enabled printer without downloading drivers. Bluetooth may soon be a standard interface on many cell phones, handheld computers, and even home appliances. However, it is going to take sometime before the hardware and software issues are resolved completely. Bluetooth operates at 2.4GHz, and is subject to the same interference problems as 802.11b and 802.11g.