Wi-Fi continued..

Lets continue with the discussions about WiFi.

3 Key enabling technologies in 802.11n and 802.11ac

Why are 802.11n and 802.11ac drastically better than the previous versions/standards? As we disucssed in LTE, there are certain key enabling technologies. Lets discuss some of these here.

a. Extended channel binding
The bandwidths in ac are 80/160MHz facilitating higher data rates.

b. MIMO spatial streams
In case of 802.11ac upto 8 MIMO streams are supported.

c. Multi-user MIMO
I really find the concept of multi-user MIMO very exciting. Here in case of WiFi, multiple stations can receive and transmit data streams simultaneously.

d. Higher Modulation techniques 
Upto 256 QAM is supported in 802.11ac.

4. A peek into future

I was reading more about the future of WiFi, I came across an interesting presentation related to something called WiFi 3!! This is a technology developed by Edgewater Wireless.  Do read more on their website, I will just give a brief introduction to the same.

WiFi3 provides 50X performance improvement. They are using a multi channel (3) approach for the same. They are providing three channels on a chipset hence  giving higher throughput. They are promising better QoS and security as well.

WiGiG is an alliance for Gigabit WiFi, to support the increasing data rates, it is necessary to implement Gigabit WiFi.  The whitepaper on their website is a must read.
Here are some f the specifications they have metioned

1. Data transmission rates upto 7Gbps are supported.
2. Designed to support low power mobile devices.
3. Supports beamforming, maximizing signal strength.
4. Also supports high performance implementations like HDMI, DisplayPort, USB.

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Wi-Fi : The standard of Past, Present , Future

It is really tough to imagine life without WiFi. GSM/CDMA/LTE everything is great but when it comes to home/office internets no one can beat WiFi. There is no work around for this standard. Understanding WiFi and the related technicalities is my task for the month!! Have you ever tried downloading IEEE standards? The 802.11 comprises of 2793 pages..Lets start understanding WiFi from scratch.
Lets begin with the origin of WiFi..Well the story behind the name is not interesting as bluetooth. It all started around early 1980s and now we are talking about Gigabit speeds!! IEEE started standardization with 802.11 - 1997.  
The 802.11 -1997 or also known as 802.11 legacy mode is rarely used. The data  rates then were upto 2 Mbps. Now we are moving towards 802.11ac that theoretically enables a speed of 1Gbps. This technology has seen a huge increase in the data rates. Although the ranges have not changed much (well it depends on what does 2.5 times increase means to you!!) May be in the coming month we can talk about FiWi.Yes FiWi and not WiFi. 
WiFi networks or WLAN (Wireless Local Area Networks) are based on this IEEE 802.11 standard or what is popularly known as WiFi. 

Lets divide the WiFi discussion into these parts.
1. Architecture and terminology
2. An overview of 802.11 from a to ac.
3. 802.11 Protocol
4. Key enabling technologies in 802.11n and 802.11ac
5. A peek into future

PS : I am reading some of these topics for the first time so please do correct me if I am wrong. As I have already said, I am no expert!!

1. Architecture and terminology

WiFi has a super simple architecture, Remember the LTE networks (by the way which are simpler than the previous generations) even that network is way complex than the WiFi network. 

Yes it is this simple, it has the distribution system, access point and base station. That is it. Lets look at each of these.

A. Distribution system
This is the communication system between access points. It is the backbone network and 802.11 does not have any specifications for this.

B. Access Points 
These are the points that convert whatever 802.11 data frames to other.

C. Stations
These are our devices. Tablets/phones/laptops/desktops/ebook readers etc.

There are two different types of WiFi networks. 
Independent and Infrastructure networks. There are some definitions one should know to be more comfortable while reading the literature.
Like
Basic Service Set (BSS) : stations which communicate with each other and form a service area.
Extended service Set (ESS) : Extended service area by linking BSS.

2. An overview of 802.11 from a to ac.
Lets skip the Legacy mode for now. Detailed description can be found on IEEE website. Wikipedia also has a good page dedicated for the same.

A. 802.11 a : It was designed for 3.7Ghz and 5Ghz frequency. Uses OFDM scheme and has 52 channels. modulation upto 64QAM. Range is 120m outdoor.
Surprisingly with higher power range upto 5km can be obtained. Data rates upto 54Mbps are supported.

B. 802.11 b : Designed for 2.4 GHz, 20 MHz bandwidth, Data rates upto 11 Mbps are supported. DSSS technique was used. Outdoor range of 140m.

C. 802.11 g : Operating frequency and bandwidth and range is same as b, but supports higher data rates (upto 54Mbps). Uses OFDM and DSSS.


D. 802.11 n : Supports operating frequencies 2.4 and 5 GHz. Bandwidth can be 20 or 40 MHz and hence supported data rates are upto 72.2 or 150 Mbps. OFDM scheme is used. 4 stream MIMO can be used.

E. 802.11 ac : Designed 5GHz, supports bandwidth from 20 to 160 MHz and hence data rates upto 866.7. MIMO techniques have been used upto 8 streams. 

Exact information about timlines of these standards can be found at


http://grouper.ieee.org/groups/802/11/Reports/802.11_Timelines.htm


In the next blog, Lets discuss the remaining topics.

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