WiFi is a mostly known type of wireless network technology used these days. Actually WiFi is the trademark of the WiFi Alliance, which is a trade association established to promote wireless LAN technologies, as well as to provide interoperability standards and testing. WiFi operates on the unlicensed ISM spectrum. The standard for WiFi is IEEE 802.11 which was derived from the 802.3, Ethernet. But WiFi became popular with the introduction of 802.11b. There are few reasons, why WiFi become popular. Among that the ability to easily provide a wireless extension to their existing local area network is the major concern.
WiFi operates on the Data Link layer of the OSI architecture.
In Ethernet, when we want to transmit data, we have to consider some points.
- Check whether anyone else is transmitting.
- If the channel is busy, listen until it is free.
- When the channel is free, transmit data immediately.
Also it added a Collision Detection (CSMA/CD) mechanism as well. But with the WiFi, due to hardware limitations of the radio, it cannot detect collisions while sending data. So instead of using a CSMA/CD, WiFi uses a Collision Avoidance (CSMA/CA) method. Where each sender attempts to avoid collisions by transmitting only when the channel is sensed to be idle, and then sends its full message frame in its entirety. Once a packet is transmitted, it waits for a acknowledgment to send the next packet.
As we talked IEEE 802.11 is the standard for WiFi, but there are more upgrades to the standard as well. There are addressed with a letter at the end of the 802.11 general standard.
These variations come with higher throughput, better modulation techniques, multi streaming, and many other new features. Today, the “b” and “g” standards are the most widely deployed and supported. Both utilize the unlicensed 2.4 GHz ISM band, use 20 MHz of bandwidth, and support at most one radio data stream. Depending on your local regulations, the transmit power is also likely fixed at a maximum of 200 mW. Some routers will allow you to adjust this value but will likely override it with a regional maximum.
When talking about the WiFi performance, WiFi networks also created one of its
biggest performance challenges: inter and intra cell interference. The WiFi standard
does not have any central scheduler, which also means that there are no guarantees on
throughput or latency for any client. All traffic both within your own network, and in nearby WiFi networks must compete for access for the same shared radio resource. Let’s see some of the characteristics,
- WiFi provides no bandwidth or latency guarantees or assignment to its users.
- WiFi provides variable bandwidth based on signal-to-noise in its environment.
- WiFi transmit power is limited to 200 mW, and likely less in your region.
- WiFi has a limited amount of spectrum in 2.4 GHz and the newer 5 GHz bands.
- WiFi access points overlap in their channel assignment by design.
- WiFi access points and peers compete for access to the same radio channel.
When talking about the performance optimizations for WiFi, we can do nothing much. Because of WiFi provides no bandwidth or latency guarantee, we have to strict to some basic optimizations as below,
- Leverage un metered Bandwidth.
- Adapt to variable Bandwidth.
- Adapt to variable Latency.
Hope now you have an idea about WiFi and optimizations. See you soon with another important topic. Thank You!