[Getting to Know Wi-Fi 01] The Evolution of the Wi-Fi standards

萌妹子
萌妹子  Junior  (1)
8 months 18 days ago  View: 4278  Reply: 1

The Wi-Fi standards are the key to understand Wi-Fi. Devices at both ends must use the same/compatible protocols and standards to communicate with each other. Learning the evolution of Wi-Fi standards helps you better understand Wi-Fi.


Wi-Fi is the name of a certification and we can see it on certified products. Its core is the IEEE 802.11 series standards of Wireless Local Area Networks (WLAN).


112901zxzm4cnu3euqznxq.png?image.png


Now, let's learn about the milestone IEEE 802.11-1997, IEEE 802.11a, 802.11b, 802.11g, 802.11n and 802.11ac protocols in the IEEE 802.1 series and see how Wi-Fi rates have increased from megabit/s to gigabit/s.


112919sgb1i0avhbqz2dvp.png?image.png



1. IEEE 802.11-1997 - foundation

In 1990, the IEEE 802 Standardization Committee established the IEEE 802.11 standard working group, which released the IEEE 802.11-1997 standard in 1997. The physical layer works at the 2.4 GHz frequency band and the designed total data transmission rate is 2 Mbit/s. IEEE 802.11 defines the WLAN communication protocol from the physical layer to the MAC layer in detail, laying a foundation for subsequent protocols.



2. IEEE 802.11b: Works at 2.4 GHz and increases the rate to 11 Mbit/s

In 1999, IEEE launched the IEEE 802.11a and IEEE 802.11b protocols.


Based on IEEE 802.11-1997, IEEE 802.11b still works at the 2.4 GHz frequency band and increases the rate to 11 Mbit/s using improved technology. At that time, the 2.4 GHz frequency band can be used in most countries, and IEEE 802.11b is widely used.


To ensure the compatibility of WLAN products from different vendors, some WLAN device manufacturers set up an industrial consortium – Wireless Ethernet Compatibility Alliance (WECA) and renamed it as the well-known Wi-Fi Alliance. Wi-Fi Alliance set up a test program to verify the compatibility of 802.11b products, which is called Wi-Fi certification. The products certified by this program can use the Wi-Fi Certified label. Later, the scope of Wi-Fi certification gradually extended to the entire IEEE 802.11 series standards. The Wi-Fi Alliance promotes the compatibility certification of Wi-Fi products worldwide and develops WLAN technologies under the IEEE802.11 standards.


Currently, the IEEE 802.11 series standards have become the most popular WLAN standards in the world. Wi-Fi is widely used to replace the entire IEEE 802.11 series standards. This is why Wi-Fi and WLAN are often used interchangeably.


3. IEEE 802.11a: Works at 5 GHz and introduces the OFDM technology

IEEE 802.11a works at the 5 GHz frequency band and uses the Orthogonal Frequency Division Multiplexing (OFDM) technology at the physical layer, which effectively reduces the impact of multipath attenuation and improves spectrum utilization, increasing the IEEE 802.11a rate to 54 Mbit/s.

However, because of the high cost due to slow 5 GHz component development and the limited 5 GHz channels, the IEEE 802.11a has not been put into large-scale commercial use despite the higher rate.


 

4. IEEE 802.11g: Uses the OFDM technology at the 2.4 GHz frequency band

In 2001, United States lifted the restriction that the OFDM technology should not be used at 2.4 GHz frequency bands. Therefore, in the IEEE 802.11g standard released in 2003, the 2.4 GHz frequency band uses the OFDM technology and increases the rate of the 2.4 GHz frequency band to 54 Mbit/s, and is backward compatible with IEEE 802.11b. The launch of IEEE 802.11g met the bandwidth requirements of people at that time and greatly promoted the development of WLAN.


 

5. IEEE 802.11n: Works in dual-band mode and introduces MIMO and channel binding

The IEEE 802.11n protocol launched in 2009 works at the 2.4 GHz and 5 GHz frequency bands. It uses technologies such as MIMO and 40 MHz bandwidth to increase the rate of 2.4 GHz and 5 GHz to 600 Mbit/s and is backward compatible with IEEE 802.11a, IEEE 802.11b, and IEEE 802.11g.


 

6. IEEE 802.11ac: Works at the 5 GHz frequency band with further improvement

After the IEEE 802.11n protocol was launched, IEEE began to develop the next-generation WLAN standard protocol, IEEE 802.11ac. The IEEE 802.11ac standard was officially released in 2013 and was improved on the basis of IEEE 802.11n. Its operating frequency band is 5 GHz, the theoretical rate reaches 6.933 Gbit/s, and it is downward compatible with IEEE 802.11a and IEEE 802.11n.



7. EEE 802.11ax: next generation protocol in development

The pursuit of high bandwidth has never stopped. Currently, the WLAN standard in development is IEEE 802.11ax, which is expected to be officially released in 2019. IEEE 802.11ax works at the 2.4 GHz and 5 GHz frequency bands and is downward compatible with IEEE 802.11a/b/g/n/ac. Devices presented at CES 2018 showed a top speed of 11 Gbit/s.



The following table lists the technical specifications of the IEEE 802.11 series standards:

Time

Standard

Frequency Band

Channel Bandwidth

Theoretical Maximum Rate

Physical Layer Technology

Antenna Structure

Compatibility with Other 802.11 Standards

1997

802.11-1997

2.4 GHz

22 MHz

2 Mbit/s

FHSS/

DSSS

1×1 SISO

Incompatible

1999

802.11a

5 GHz

20 MHz

54 Mbit/s

DSSS

1×1 SISO

Incompatible

1999

802.11b

2.4 GHz

22 MHz

11 Mbit/s

OFDM

1×1 SISO

Incompatible

2003

802.11g

2.4 GHz

22 MHz

54 Mbit/s

OFDM/DSSS

1×1 SISO

Compatible with 802.11b

2009

802.11n

2.4&5 GHz

20/40 MHz

600 Mbit/s

MIMOOFDM

4×4 MIMO

Compatible with 802.11a/b/g

2013

802.11ac

5 GHz

20/40/80/160 MHz

6.933 Gbit/s

MIMOOFDM

8×8 MIMO

Compatible with 802.11a/n


Huawei single-band ONTs support IEEE 802.11 b/g/n (2.4 GHz) and dual-band ONTs support IEEE 802.11 b/g/n (2.4 GHz) and IEEE 802.11 a/n/ac (5 GHz).

113120zz98a33srz9sar2a.png?image.png

user_3301521
user_3301521  Jackeroo 
8 months 10 days ago
Thanks alot, This is a helpful topic