OFDM WLAN system utilizing smart antenna DBF-IC for mobile terminal

The work presents a high throughput (over 20 Mbps) IEEE 802.11a wireless local area network (WLAN) system applicable to wireless TV and AV (audio-video). Multipath fading deteriorates the system throughput and its service area. A popular measure to overcome multipath fading has been a smart antenna at an access point (AP). However, this measure does not work well for the IEEE standard. The MAC layer standard requires every mobile terminal (MT) to receive all signals from the AP, and every MT cannot necessarily receive them from an AP with a smart antenna. We have developed a high throughput IEEE 802.11a WLAN system which provides each MT with a smart antenna, instead. This system makes it possible for each MT to listen to all signals from the AP and not to suffer from multipath fading. The digital beam forming IC (DBF-IC) we have developed for the system improves the received signal SNR and compensates the distortion due to frequency-selective fading. Actual system measurements with this IC show that the service area expands to double that of the conventional system with omni antenna.