Product category:
Communications ICs (Wired)
News Release from: IMEC
Edited by the Electronicstalk Editorial
Team on 14 July 2004
MIMO system uses SDMA for IEEE802.11n
IMEC is claiming a milestone in research on smart MIMO (multiple input/multiple output) systems, which will enable optimal use of resources in wireless networks.
IMEC is claiming a milestone in research on smart MIMO (multiple input/multiple output) systems, which will enable optimal use of resources in wireless networks IMEC's solution distinguishes itself from current multiple antenna techniques by optimising multimode operation, including spatial transmission preprocessing
This article was originally published on Electronicstalk on 20 Feb 2002 at 8.00am (UK)
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IMEC's prototype shows how the cell capacity can be radically improved to more than 100Mbit/s thanks to spatial processing.
The proof-of-concept demonstrator comprises a two-antenna access point, a dedicated MIMO front-end operating at 5GHz, and two single-antenna user terminals or one single two-antenna terminal.
The solution is unique because it performs the upgrade through spatial division multiple access (SDMA) processing at the transmitter only, allowing several users with single antenna (legacy) terminals to communicate simultaneously in the same frequency band.
With this solution, the multi-user capacity is effectively doubled without upgrading the user terminals.
The flexible scheme also accomplishes transmission up to 108Mbit/s to one (multiple antenna) terminal and can increase the coverage range by a factor two to five thanks to spatial diversity.
The transmitter first executes digital signal processing based on channel knowledge that a specific combination of the multiple signals from each antenna can be sent.
Each antenna at the terminal side receives one distinct stream, free from interference from the other stream(s).
This scheme was conceived as an access point processing but it can also be used at the terminal side.
The channel information is achieved based on channel estimation on the reverse link, as such minimising the elapsed time between the estimate and the actual precompensation.
A special calibration procedure compensates for nonreciprocity in the front ends.
The concept is demonstrated on IMEC's proprietary Picard (platform for integrated communication applications, research and demonstration) prototyping platform.
The baseband and MAC processor are implemented in FPGAs.
The 5GHz front end, which is tailored for MIMO operations, will be further integrated in a system-in-a-package.
Currently, the prototype also incorporates space-time block coding (STBC) and spatial multiplexing employing receive processing.
The cross-layer resource controller guarantees an optimal mode selection, trading off cost (power consumption) and performances (rate, latency).
Further research investigates the combined transmit-receive processing, and SDMA separation of MIMO terminals in which a multiple-antenna transmitter sends to several multiple-antenna receivers.
This smart MIMO technology is a building block in IMEC's multimode terminal programme.
The combination of the smart MIMO technology with a flexible air interface will enable multimode terminals that can seamlessly switch between different communication types, such as WLAN and cellular communications.
Ultimately, this will lead to the development of a multi-hop network in which each device can be used as a terminal or access point, depending on the availability of power.
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