MIMO-OFDM High Speed Wireless Communication from NASA

http://www.nexttechs.com/highlights/tech.asp?id=3135


ID: COM-WIR-00009

Title: MIMO-OFDM High Speed Wireless Communication


Technology Business Brief:

MIMO-OFDM is proven technology to improve signal quality and data rate for
wireless communications. The global growth of interest in the wireless
Internet and digitized audio and video, coupled with a growing wireless
high-bandwidth infrastructure leads to a rapidly expanding market for
wireless multimedia services. To cope with the growth, wireless services
providers today are faced with a number of challenges, which include the
limited availability of the radio frequency spectrum and a complex
time-varying wireless environment. In near future, wireless devices will
have features for always-available connection, higher data rate, longer
distance, low-power consumption, better quality of service (QoS), fewer
dropped packets, and higher network capacity in order to improve service
quality for rapid service expansion and configurations. Combining OFDM with
Multiple Input and Multiple Output (MIMO) equipment, wireless local access
networks (WLANs) is the most promising technology for delivering high data
rates and robust performance.

Using IEEE 802.11n as a standard, this MIMO technology is focusing on a
Digital Signal Processing (DSP) based Space-Time-Frequency (STF)
coding/decoding along with OFDM modulation. This MIMO technology can deliver
a high-speed wireless transmission rate up to 600 Mbps and three times more
transmission distances than IEEE 802.11g. The current IEEE802.11n can
achieve 300 Mbps. Ultra-wideband (UWB) is another high-speed wireless
technology but UWB is limited to a range of 10's meters. MIMO-OFDM has the
ability to reach 500 meters indoors.

Use of multiple antennas in the wireless link with appropriate
space-time-frequency (STF) coding/OFDM modulation and demodulation/decoding
is the key technology that makes MIMO-OFDM superior. The difference between
a MIMO-OFDM system and a conventional system comes from the use of multiple
antennas, STF-coding/interleaving, STF pre-filtering, and post-filtering and
STF decoding/deinterleaving.

Advantages:

MIMO-OFDM wireless system has the following advantages over a conventional
system:

Higher transmission rate (Spatial multiplexing)
Longer distance (coverage)
Diversity Gain
Reduced interference
MIMO can combine with Code Division Multiple Access (MIMO-CDMA) to achieve
the same benefit as WLAN's to Cellular products. MIMO-OFDM DSP can speed up
the production time and hence lower the cost to produce. MIMO-OFDM is more
reliable than conventional communication devices.

Applications:

Wireless LAN (WLAN)
Wireless USB (WiMedia)
Wireless multimedia entertainment
Voice over WLAN