NTT Research and Development 2011 Review of Activities

Overview

The wireless home network is desirable as a means of connecting various individual terminals to an optical fiber that run into the subscriber's home. Home networks require stable transmission of high-volume video traffic, etc. To meet this requirement, NTT Laboratories developed a multi-user MIMO^*1 transmission prototype that enable simultaneous transmission of data to multiple destination terminals at the same time and on the same radio frequency without cross-interference (SDMA^*2) for the next-generation high-speed wireless LAN (IEEE 802.11ac). The prototype employs a recursive weight calculation algorithm and a compressed CSI^*3 feedback technique. Thus we achieved real-time multi-user MIMO transmission at over 1 Gbit/s for the first time in the world.

Features

• A maximum total of 1.62 Gbit/s real-time wireless transmission to 6 terminals multiplexed by SDMA with multi-user MIMO technique.
• Recursive weight calculation algorithm that reduces circuit scale to about 1/6 in order to implement beam-forming control that has the accuracy needed for multi-user MIMO in an FPGA^*4.
• Compressed CSI feedback technique capable of reducing CSI data volume to about 2/3 when a terminal sends the CSI to an access point for beam-forming control, thus shortening the overhead time.

Application scenarios

• Simultaneously video viewing of high-definition contents of IPTV distributed over the optical fiber network and for HD video players by family members in different rooms on wireless TV sets and computers.
• Networking by wireless connection of diverse types of terminals in the home, ranging from high-speed high-volume communication devices such as high-definition TVs to relatively low-speed devices such as sensors.

• *1 MU-MIMO: Multi-user, Multiple Input, Multiple Output
• *2 SDMA: Space Division Multiple Access
• *3 CSI: Channel State Information
• *4 FPGA: Field Programmable Gate Array