A2Z Computer Solutions --- Wireless Internet Overview

There are a number of different variations on the basic concept of 802.11 (wireless) networking. The most common is 802.11g - sometimes called 'Wi-Fi'. A faster version is 802.11n. Older versions have a different letter after the 802.11 for example 802.11a and 802.11b The “a” and “b” networks are becoming less and less common with g and n taking over.

The wireless networking is usually very short range - commonly the maximum range is somewhere between 100 ft and 100 yds from the wireless hub depending on obstructions. Computers use a wireless modem which connects via a radio signal to a wireless network hub. Desktop computers either have a card that fits into a spare slot in the computer or perhaps an accessory connection that plugs into a USB slot. Laptop computers typically use a PC-card (PC-MCIA) card device. This means multiple computers can connect to the web and download files, communicate via email and even play online bingo without the need for Ethernet cables or sometimes inconvenient proximity to the router or a telephone line. The wireless hub looks just like a normal hub, except for one or two short antennas.

A, B, G, N Explained

A
The 802.11a amendment to the original B created in 1999. The 802.11a standard uses the same core with a maximum raw data rate of 54 Mbit/s, which yields realistic net achievable throughput in the mid-20 Mbit/s. The data rate is reduced to 48, 36, 24, 18, 12, 9 then 6 Mbit/s if required. 802.11a has 12 channels, 8 dedicated to indoor and 4 to point to point. It is not interoperable with 802.11b, except if using equipment that implements both. Since the 2.4 GHz band is heavily used, using the 5 GHz band gives 802.11a the advantage of less interference. However, this high carrier frequency also brings disadvantages. It restricts the use of 802.11a to almost line of sight, necessitating the use of more access points; it also means that 802.11a cannot penetrate as far as 802.11b since it is absorbed more readily.

B
The 802.11b has a maximum raw data rate of 11 Mbit/s. 802.11b is usually used in a point-to-multipoint configuration, wherein an access point communicates via an Omni-directional antenna with one or more clients that are located in a coverage area around the access point. Typical indoor range is 30 m (100 ft) at 11 Mbit/s and 90 m (300 ft) at 1 Mbit/s. With high-gain external antennas, the protocol can also be used in fixed point-to-point arrangements, typically at ranges up to 8 kilometers (5 miles) although some report success at ranges up to 80–120 km (50–75 miles) where line of sight can be established. 802.11b cards can operate at 11 Mbit/s, but will scale back to 5.5, then 2, then 1 Mbit/s if signal quality becomes an issue. Since the lower data rates use less complex and more redundant methods of encoding the data, they are less susceptible to corruption due to interference.

G
In June 2003, a third modulation standard was ratified: 802.11g. This works in the 2.4 GHz band (like 802.11b) but operates at a maximum raw data rate of 54 Mbit/s. 802.11g hardware is compatible with 802.11b hardware. In older networks, however, the presence of an 802.11b participant significantly reduces the speed of an 802.11g network. Even though 802.11g operates in the same frequency band as 802.11b, it can achieve higher data rates because of its similarities to 802.11a. The maximum range of 802.11g devices is slightly greater than that of 802.11b devices, but the range in which a client can achieve the full 54 Mbit/s data rate is much shorter than that of 802.11b. Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include microwave ovens, Bluetooth devices, and cordless telephones.

N
In January 2004, IEEE announced that it had formed a new 802.11 amendment to the 802.11 standard for wireless local-area networks. The real data throughput is 100Mbit/s, and is up to 50 times faster than 802.11b, and up to 10 times faster than 802.11a or 802.11g. 802.11n builds upon previous 802.11 standards by adding MIMO (multiple-input multiple-output). MIMO uses multiple transmitter and receiver antennas to allow for increased data throughput.

Satellite
Satellite Internet access may be worth considering. It's ideal for rural Internet users who want broadband access. Satellite Internet does not use telephone lines or cable systems but instead uses a satellite dish for two-way (upload and download) data communication. Upload speed is usually considerably less than download speeds. Cable and DSL have higher download speeds, but satellite systems are about 10 times faster than a normal modem. Satellite Internet consists of:
• Approximately a two-foot by three-foot dish
• Two modems (uplink and downlink)
• Coaxial cables between dish and modem
The key installation planning requirement is a clear view to the south (when in the northern hemisphere) or the north (when positioned on the southern hemisphere), since the orbiting satellites are over the equator area. And, like satellite TV, trees and heavy rains can affect reception of the Internet signals. Some satellite-Internet service still requires you to have a dial-up or cable modem connection for the data you send to the Internet. The satellite transmits the data to your computer from the same type dish that would allow you to receive a television program.

Cellular
Now 2G and 3G cellular services are available. 3G speeds are usually 100 kbps. All the major providers offer PCMCIA cellular cards for laptops, most phones have fairly inexpensive connectivity kits ($50 or less), and some phones even include built-in Bluetooth support for cable-less connection to Bluetooth-enabled computers. Cellular internet access uses the cell phone network to connect. The performance could range anywhere from 14.4 kbps to 300+ kbps, but typical digital speeds are 50-120 kbps up/down. 300+ kbps is just starting to arrive in very few cities, but it is expected to continue replacing existing networks. Wherever you can get a cellular signal, you can get cellular internet access. Faster speeds are only available when you have a digital signal. If the signal drops, your connection will drop as well, just like any other phone call.

Sources - Wikipedia