MIMO-OFDM High Speed Wireless Communication from NASA

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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.


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.


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

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