The development and future of Wi-Fi - Part 1

Network Administration - Wi-Fi technology first appeared in 1997. Today the technology has been developed very strongly and is currently in 802.11n standard. In this series, I will show you some basic knowledge about this technology, along with a brief outline of its development .

Introduce

The 802.11 standard is the standard used for Wi-Fi technology started in 1997 published by the Institute for Electrical and Electronics Engineers (IEEE). Over time this standard has been released and today we have the 802.11n version.

Institute for Electrical and Electronics Engineers (IEEE)

Let's start with a brief introduction about what IEEE is. IEEE is a professional science organization built to support scientific research activities and promote the development of science and technology in the fields of electronics, telecommunications, information technology, and science. study computer. The institute consists of many electrical and electronic engineers (many advanced degree holders are working at prestigious universities around the world), it can be said that they are experts in each field. The organization of these standards comes from the need to have widely accepted standards to ensure compatibility between devices worldwide. This is one of IEEE's most difficult tasks, ensuring widespread acceptance; a task that they do not always perform. The standards published by IEEE cover all areas of electronic engineering related to computer networks. When someone analyzes standards, it is important to remember that performance is often not the design goal of standards. In fact, the standard may not be perfect. However, as we suggested above, a standard is only valid if it is widely accepted; This goal is the red thread throughout the process of designing standards.

The IEEE subcommittee that this series introduces is the LAN / MAN subcommittee. This subcommittee has been assigned 802 identifiers, so each standard determined by this committee will start with the 802 identifier. Indicator 11 in 802.11 is related to internal modulation. space; so all 802.11 standards will be published by 802 subcommittee and use spatial modulation. You will often see the 802.11 index and many other standards for the topic written along with the time behind the designator, such as 802.11-1997. This recorded time is the time of standard announcement. When making a standard, the subcommittee will publish the latest updates and this time will change according to the latest announcement. In addition, you will often find identifiers that are described along with a lowercase letter, such as 802.11b. Here printed letters often indicate modifications to the originally published standard. In the case of 802.11, print letters are often assigned to approved modifications for 802.11 technology support for greater speed, wider range, better reliability, or a combination of all three. above element.

802.11-1997

The first published standard for Wi-Fi was 802.11-1997, which was published in 1997. You need to remember that when we said IEEE was not always successful in the goal of widespread adoption. ? This is such a case. The original standard received very little recognition. Partly because its low bit rate is only about 1 or 2MB / s. The actual bit rate depends on the physical link used to transmit the data. The 802.11-1997 standard has allowed three different technologies to be used:

The low approval rate for this technology standard is due to a low bit rate, but it is also partly due to the cost of technology. In 1997, the design of receivers and transmitters required to use the 802.11-1997 standard was quite expensive at the top of computers, especially laptop computers, because of their mobility required. Wi-Fi technology). Later, however, the 802.11 standard was updated in 1999 with 'a' and 'b' identifiers getting more consensus. Although 802.11a and 802.11b were released simultaneously in 1999, only 802.11b was widely accepted.

802.11a and 802.11b

802.11a is an improved standard from 802.11-1997. While 802.11-1997 can only transfer data at 2MB / s, 802.11a can transmit data at 54 MB / s. This increase in data transfer rate is due to the use of a 5GHz frequency instead of the 2.4GHz frequency used in 802.11-1997 (the frequency used for the Frequency Hoping Spread Spectrum and the Direct Sequence Spread Spectrum options; No infrared options). In addition to increasing speed, another advantage in using 5GHz frequency is that there are not many devices that use this frequency, so the ability to cross noise between devices will decrease. However, using 5GHz band also has a big disadvantage. Since the 5GHz frequency uses shortwave (the frequency is inversely proportional to the wavelength; therefore, the higher the frequency, the shorter the wavelength), so this technique has a poorer coverage and the signal is hampered. more by obstacles like walls; there are not even many walls but if the signal is transmitted in space with many objects (tables and chairs, .) the signal strength is greatly reduced.

802.11b inherits Direct Sequence Spread Spectrum from the original 802.11-1997 standard, along with the 2.4 GHz operating frequency. Continued use of the 2.4 GHz frequency has both advantages and disadvantages. The advantage here is that this frequency is not adjusted and so the cost of production will be cheaper. However, the drawback is that there are many devices that use this frequency (extended phones, child checkers), all of which can interfere with each other.

The major change in 802.11b is the maximum data rate. The maximum data rate of 802.11b is about 11MB / s, the number can compare with the traditional Ethernet speed in 1999 and 2000. With this speed, many customers can use Wi-Fi, inherited all the advantages of mobility without the disadvantages of speed. Along with the reduction in the cost of technology has made 802.11b technology widely accepted.

802.11g

As the Ethernet speed increases, this has affected the 802.11 standard. In 2003, IEEE approved 802.11g. This 802.11g standard operates at 2.4 GHz, like 802.11b and 802.11-1997, but it uses the Orthogonal Frequency Division Multiplexing (OFDM) technique used by 802.11a. This OFDM technique allows 802.11g to operate at 54 MB / s; a significant increase in speed compared to 802.11b is 11 MB / s. Like 802.11b, 802.11g is also widely accepted for both customers and businesses.

802.11n

802.11n is the latest standard today, this standard has just been approved in September. 802.11n uses a new technology to increase the data rate: Multiple Input / Multiple Output (MI-MO). We will introduce you to the 802.11n standard in the next part of this series, but you can guess right from MI-MO that 802.11n will work with multiple transceivers and this has given allow it to increase data rate.