Sunday, August 8, 2010

The IEEE 802.11x


  • A. The IEEE 802.11x
    The IEEE (Institute of Electrical and Electronics Engineers) is the standardization of technology standards used in computer science. He sleeps on paper all their characteristics such as Ethernet, USB, etc.. However, the WECA (Wireless Ethernet Compatibility Alliance), better known as the WiFi Alliance (association of more than 200 players in the wireless market ), which guarantees a set of quality control and interoperability testing that a product matches the features standardized. This product then receives the label Wi-Fi, ensures quality and interoperability.
    A network WiFi is a network conforming to the IEEE 802.11x (where x is replaced by a letter). In other countries, it is called WLAN (real name of the standard), which is more correct.
     
  • B. 802.11a other WiFi5 called because it operates on frequency bands of 5 GHz, achieves a maximum throughput of 54 Mbps (30 Mbps actual) over a distance of 10 meters. She was reserved in Europe for military use. It uses OFDM modulation radio.  
  • C. 802.11b
    It is the first standard to the widespread use of wireless transmissions, while experiencing a great commercial success. It provides theoretical speeds of 11 Mbps (6 Mbps actual) on the frequency band 2.4 GHz. The maximum signal range is 100 meters indoor and 300 meters outdoors, its scope is much smaller in practice (30 and 100 meters actual). It uses radio modulation DSSS DSSS and HR.
    Eager as the standard 802.11g soon arrived, manufacturers have created an evolution of that standard, 802.11b +, which can increase the flows 22 and 44 Mbit / s (11-20 Mbps real). These materials were compatible with 802.11b, but holding off their speed to 11 Mbps
     
  • D. 802.11g
    Always based on radio transmissions of 2.4 GHz and the same ranges as 802.11b, this standard can reach theoretical speeds of 54 Mbps (26 Mbps actual). This is the most common material on the market today. It is compatible with previous 802.11a and b. It uses DSSS modulation radio, HR-DSSS and OFDM.
    Always so impatient, manufacturers have developed proprietary standards (compatible only with material from the same brand and same type), the 802.11g + 802.11g SuperG turbo, changes to achieve speeds of 108 Mbps.
     
  • E. MIMO Pre-N or Draft-N Warning! It is not a true standard! It is (such as changes in other standards) the result of competition between manufacturers to start before other materials always more technologically advanced, although for this he must sell hardware without Standard Common and therefore no guarantee of interoperability (or operation), all supported by the WiFi Alliance. MIMO has been developed to overcome the weak point of the wi-fi: the decrease in signal strength (ie flow and maintaining a stable connection) from the transmitter and receiver are far away or it takes over obstacles or operate in an environment with areas of interference. It provides better speeds and more stable by distance and works much better indoors. Equipment for Multi Input Multi MIMO Output is equipped with multiple antennas (3-9 according to manufacturers) who receive or transmit simultaneously. According to the manufacturer, the material is called Pre-N, Draft-N, Range-Max, SRX. We can not achieve the maximum flows, advertised 300 Mbps, with materials of the same brand or type. For the most part, they are compatible with 802.11a/b/g (price reduction of flow velocity with the standard) and should also be forthcoming with the 802.11n standard, but nothing is certain yet.
  • F. 802.11n eagerly awaited and repeatedly delayed (which has prompted manufacturers to create the standard Draft [draft] or Pre-N), this standard is very promising. It is expected to reach speeds of wired networks, with a throughput of 540 Mbit / s (100 Mbit / s real) and a range of 100 meters real. It will integrate MIMO technology and should be compatible with older standards for operation in mixed mode. This will have heterogeneous operating speed transmissions in 802.11a, b or g with the old equipment and with the new 802.11n. It uses radio modulation MIMO-OFDM. The 802.11n uses frequencies of 2.4 and 5 GHz and only works in infrastructure mode with a central access point to which all clients connect. It should be finally ratified by IEEE in April 2007.
  • G. 802.11s is the future of wi-fi in the coming months or years. This standard will be based on the principle of mesh internet. Any point in the network receives the data and sends them back if they did not serve. Compatible with older standards, scope and transmission speeds are obviously improved.  
  • H. Complementary Standards
    802.11i
    This standard ensures that the equipment may use an encryption data with enhanced security through encryption of AES, the most powerful used in wi-fi. It is usable on all products 802.11.
    802.11e
    It ensures that the hardware can use the system QoS (Quality of Service) that allow parties to reserve the desired bandwidth flows. For example, providing 50% of the bandwidth to stream Internet, ensures that all networked computers can surf without a proper software peer-to-peer comes to appropriate the full capacity of the line.


1 comment:

  1. There is no single 802.11x standard. The term IEEE 802.11 is also used to refer to the original 802.11, which is now sometimes called "802.11legacy".

    ReplyDelete