Monday, March 24, 2014

Explanation of the 802.11 Wireless Technology Standard

Whether you are shopping for a replacement internal wireless network interface card (NIC), an add-on NIC for a desktop computer, a new device with an integrated wireless NIC, or a wireless radio, you may find yourself wondering what the differences are for the 802.11 standard listed on each device.  Currently, there are four common and one new version of the standard.  Often times laptops are for sale for $300, but you will find they are using older processors, port connections like USB 2.0 instead of 3.0, or older wireless standards, which is why the device is so cheap.  Being informed and knowing what the differences are for each of these versions can help you decide which device will best meet your needs and if you are paying an appropriate price for what you are getting.  Luckily, the 802.11 standard is maintained and overseen by the Institute of Electrical and Electronics Engineers, or IEEE, which means any device labeled with a certain 802.11 version will have similar results across brands.

Some important definitions:

Mbps - Megabits per second, or 1,000,000 bits of data.

MB - Megabytes, or 8,000,000 bits of data.  One byte is equal to eight bits.  Anytime you see a capital B, as in MB, or GB, the B is in bytes.  A lower case b, as in Mb or Gb, the b is in bits.  In general, transmission speeds are expressed in bits, while storage sizes are expressed in bytes.

Wireless Access Point / Wireless Radios / Wireless Router - a physical piece of hardware that connects to a network and acts as the communication hub for all wireless traffic on the network.  This device must have a wired connection to the network which it uses to broadcast a wireless signal transmitting wireless data as well as communicating with other devices beyond the network.

Antennas - a physical piece of hardware connected to a wireless access point to transmit data.  Also used on wireless NIC's for desktop computers to connect to the network wirelessly rather than using a data cable.

MIMO - Multiple Input and Multiple Output, uses multiple antennas on wireless access points to transmit and receive data rather than a traditional single antenna, exponentially increasing the maximum data transmit speeds.

Frequency Band - A collection of sequential channels.

Channels - A predefined radio frequency range available for use.  In the United States, channels are established by the FCC, who defines and standardizes frequency ranges based on usage types.  

Streams - The individual radio transmissions between devices such as between a laptop NIC and an access point.  The antennas on the access point is the physical medium that transports the data to and from all the devices on the network.  The stream is the actual data being communicated.

The table listed below shows each of the 802.11 standards listed in chronological order based on when they were first introduced.  

Wireless Standard Max Data Speed Frequency Band Maximum Antennas / Streams
802.11b 11Mbps 2.4Ghz 1
802.11a 54Mbps 5GHz 1
802.11g 54Mbps 2.4GHz 1
802.11n 54 - 600Mbps 2.4GHz / 5GHz 4 - added MIMO
802.11ac 466 - 1300Mbps 5GHz 8 - using MIMO

As you can see, the speeds relative to each version of the wireless standard can vary greatly.  Additionally, wireless data transfer rates within versions are affected by many things.  Some of the things that affect signal strength, and therefore data transfer speeds, are:

  • Other devices using the same frequency bands - there are many household items that utilize the 2.4GHz frequency band.  Some of these common items are microwaves, baby monitors, and cordless phone handsets.  There are far fewer items competing with the 5GHz frequency band.
  • Physical obstructions - walls, especially concrete walls, can greatly reduce the reliability of a wireless network.  In some situations, connecting to an access point on another floor in your house can be near impossible without adding additional equipment like wireless repeaters which will repeat the wireless signal to add distance to the wireless network range.
  • The distance between the device and the access point - the higher the frequency the lower the signal strength.  This means that the 2.4GHz standards are able to send their signal much further than the 5GHz standards and may be an important thing to consider depending upon how far your devices will be from the access point.
  • Versions supported by each device - devices on your network will be restricted by the speeds provided by the access point and vice versa.  In other words, if you have a wireless access point operating on the 802.11g wireless standard and purchase a laptop with a NIC operating on the 802.11n wireless standard, the laptop will not be able to take full advantage of the benefits of the 802.11n data speeds because the access point will not be able to provide those speeds.  The wireless speeds your devices will operate at will always be based on the lower of the two, either the NIC used by the device or the access point passing the traffic.
Each day we find more and more ways to use our technology devices.  Increased usage typically means larger data transfer needs.  In response to our increased needs and data consumption, the 802.11 standard is continually being updated.  Equipment utilizing the newer standards continues to be developed and provided to those who are willing to pay the price for the latest and greatest.  As with anything technology based, the longer the equipment has been available, the lower the cost will be to the consumer.  If you are replacing a device, whether it is a laptop or wireless access point, you should consider upgrading to a newer version of the wireless standard to increase your data transfer speeds.

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