Silex Unwired

Missions for Wireless LAN (1)

Posted by Y. S. on January 3, 2012

IEEE802.11b was first introduced in September, 1999.  IEEE802.11b is now recognized as the first wireless LAN standard.  Over ten years later, IEEE802.11n is now the latest standard.  The transfer speed which used to be 12Mbps is now 600Mbps (theoretical maximum value).  WEP was the first encryption technology but has been replaced by WPA/WPA2.  For initial setup, WPS is getting popular, which enables users to connect devices by just pushing a button.

In this series of articles, I would like to share my view of the future trends for Wireless LAN’s.  The first subject is about people's unstoppable thirst: "to be faster".

To Be Faster – 1:  Multi-Streaming

802.11n uses MIMO technology (see note below), to allow multiple antennas to distribute separate communication channels (streams) at both the transmitter and receiver to improve communication performance.  Put simply, as the number of streams increase, the transfer speed should be faster (Multi-streaming).  802.11n is designed to offer up to 600Mbps (theoretical value) and 4 streams (each stream offers up to 150Mbps).  Conventional 802.11n products mainly offer 1 to 2 streams although recently, 3-stream products have entered the market.

(Note) MIMO stands for Multi-Input /Multi-Output.

I'm not sure yet if 3 or 4-stream products will become common because MIMO requires multiple antennas (one per stream).  MIMO's antennas need to be installed apart (e.g. about 6cm apart for 1/2 wave/2.4GHz band), so a multi-stream MIMO device would end up with many antennas projecting from every direction.  Sheet-type or chip-type internal antennas are available for PCs and tablets so they could be kept inside the enclosures.  But smaller portable devices including Smart Phones don't have an enough space on the PCB to install antennas for multi-stream MIMO.

Summary

Multi-streaming is capable of achieving higher speed transfer without dramatic improvement of current technology.  However, it has difficulties for smaller/cheaper/low-power products. Multi-stream technology may be popular for PCs and built-in TVs.  It isn't good for small portable devices due to mechanical challenges supporting MIMO with more than 2 streams (antennas).

Tags: AR6003, Wireless Module