Airgain claims their compact, low cost smart antennas deliver the flexibility of an omni-antenna with the enhanced performance of a directional antenna, providing dramatic improvements in range that increase coverage up to four times that of premium omni-directional antennas.
Based on phased array techniques, Airgain s smart antenna directs a WiFi beam towards any active wireless device. Each smart antenna is capable of continuously monitoring network signal strength, dynamically shifting between 11, 5, and 2 mbps network speeds for maximum availability and reliability.
Perhaps a bridge with a switchable directive element would be good for mobile police or transit use. The Cerritos trial may provide some answers.
Other “smart antenna” startups are trying variations on phased arrays:
- Motia uses analog processing techniques to derive four signals from an 802.11 transmission. It uses a weighted combination of the four to determine where the sender was, then uses the same set of weights to transmit signals back. The process gets repeated for every packet, so the antenna can track a moving user. Antennas using the technology should be available next year (see Motia Launches Javelin).
- Bandspeed Inc. disclosed its Gypsy antenna in April (see Bandspeed’s Six-Eyed Gypsy ). Not NIMO, Gypsy uses a directional approach, making antennas more efficient by narrowing their focus. The system splits the 360-degree universe into six 60-degree sectors, with antennas tracking each sector rather than a full circle. Customers using Bandspeed’s technology are expected to ship at the end of next quarter.
- ZeeWaves Systems Inc. is another advocate of the directional approach. The company’s antenna can broadcast in 360 degress as a normal antenna does, but it can also narrow the angle to as little as 10 degrees. ZeeWaves’ products are in beta trials.
- Wi-Fi Plus exploits polarization to grab signals thrown away by other antennas. It does not use special signal processing. The company’s antenna is designed to pick up polarized signals usually lost. Wi-Fi Plus is shipping antennas but would like to get its product embedded into other companies’ cards.
“Smart Antennas” can take many forms. Multiple-Input-Multiple-Output (MIMO) antennas combine the signals of multiple antennas electronically for added gain and multipath rejection. Airgo Networks, named by EE Times as “the most influential radio technology of the next few years, uses a MIMO chipset said to take advantage of multipath. Airgo claims they got a coverage area three to ten times that of competing WLAN chipsets, (in high multipath areas).
MIMO antennas will be used in the IEEE 802.11n standard which plans WLAN throughput above 100 Mbits/second and above while maintaining backward compatibility with existing 802.11a/b/g. MIMO has been incorporated into the 802.16(d) standard that’s going out the door later this year.
How does MIMO work? EE Times explains.
.gif)
