29 Compare the characteristics of wireless communication standards (802.1 1 a/b/g/n- Speeds, Distance, Channels and Frequency)
There are many wireless networking specifications that exist under the umbrella, 802.11. These standards though implemented in the same way have different characteristics in terms of speed, transmission ranges and others. The main standards to be considered are:
- IEEE 802.11: This is the initial wireless standard. Two variations of the standard were implemented. In terms of transmission speeds and the radio frequency, the systems were identical, the difference was in the way data traveled through the RF media. FHSS (Frequency Hopping Spread Spectrum) was used by one and DSSS (Direct Sequence Spread Spectrum) by the other. Modern networks which are always challenging networks for speed displaced them soon. The characteristics of 802.11 are:
|
Frequency /Media |
2.4GHz RF |
|---|---|
|
Speed |
1 to 2 Mbps |
|
Topology |
Ad hoc/Infrastructure |
|
Transmission Range |
20 feet indoors |
|
Access Method |
CSMA/CA |
- IEEE 802.11a: When it comes to rate of transfer of data, this standard has left the 802.11 standards much behind. The shortcoming of this system is that it not compatible with other wireless standards 802.11b and 802.11g. The characteristics of 802.11a are:
|
Frequency /Media |
5 GHz RF |
|---|---|
|
Speed |
Up to 54 Mbps |
|
Topology |
Ad hoc/Infrastructure |
|
Transmission Range |
25 to 75 feet indoors; building materials can affect the range |
|
Access Method |
CSMA/CA |
- IEEE 802.11b: This is compatible with 802.11g and devices with earlier standards. It provides for a maximum transmission data rate of 11Mbps. The characteristics of 802.11b are:
|
Frequency /Media |
2.4GHz RF |
|---|---|
|
Speed |
Up to 11 Mbps |
|
Topology |
Ad hoc/Infrastructure |
|
Transmission Range |
Up to 150 meters indoors; the range can be influenced by the building materials that have been used. |
|
Access Method |
CSMA/CA |
- IEEE 802.11g: It is one of the most popular wireless standard adhered to these days. It is compatible with 802.11b. The characteristics of 802.11g are:
|
Frequency /Media |
2.4 GHz RF |
|---|---|
|
Speed |
Up to 54 Mbps |
|
Topology |
Ad hoc/Infrastructure |
|
Transmission Range |
Up to 150 feet indoors; building materials can affect the range |
|
Access Method |
CSMA/CA |
- IEEE 802.11n: It is the most recent to be added to the league of standards pertaining to wireless networking. It concentrates on throughput. The base is taken to be 100 Mbps and with the right conditions, it is expected to reach a level of 600 Mbps. The characteristics of 802.11n are:
|
Frequency /Media |
2.4GHZ/5 GHz RF |
|---|---|
|
Speed |
Up to 600 Mbps |
|
Topology |
Ad hoc/Infrastructure |
|
Transmission Range |
175+ feet indoors; building materials can affect the range |
|
Access Method |
CSMA/CA |
802.11n is directed towards bringing major changes in the wireless networking environment. It holds promises of greater speeds and distance. It uses a mixture of all the standards of 802.11 to enhance wireless networking to the next level. The technologies that have played an important role are:
- MIMO: It uses the technology Multiple Input Multiple Output (MIMO) which is considered as the best technology for 802.11n. MIMO uses the technique of multiplexing which raises its speed and the range that a network can cover. Multiple signals are combined and transmitted over a single line or media.
- Channel Bonding: The next factor that has played an important role is Channel Bonding. This allows channels to bond allowing for data rate to be nearly doubled. 802.11b and 802.11g standards use single channels and when channel bonding is incorporated, using two channels at one point of time becomes possible and hence transmission rates are increased.