Research Description

The POWDER over-the-air (OTA) test bed will eventually be equipped with 3 massive MIMO base stations, which will provide an excellent opportunity to obtain OTA test results at sub-6GHz frequencies.  The following area will be pursued:

• Detection and Precoding for Single Carrier Modulation (SCM) waveforms with a Cyclic Prefix:  Our intention is to perform over the air testing with POWDER to validate our simulation results.  Specifically, we will perform channel estimation using uplink pilots from the UEs and perform multi-user detection on the uplink transmissions that follow at the massive MIMO base station (BS).  The detection and precoding techniques that we plan to implement require a matrix inverse calculation for each frequency bin.  Fortunately, the same matrix inverses used for the detection process is reused for the precoding, so we intend to perform the downlink precoding within the same 1 ms frame as the UL time slots in time domain duplexed fashion.
• Channel Estimation and Channel Equalization of Filter Bank Multicarrier-based (FBMC-based) Massive MIMO Systems: We proposed a multi-user channel estimation and pilot design technique that jointly estimates all users’ channels with interleaved pilots. For the channel equalization problem in FBMC-based massive MIMO, we designed two-stage approaches that improve SINR at the receiver output. We used conventional linear combiners followed by a multi-tap fractionally spaced equalizer. Our latest paper is on the practical FBMC receivers for massive MIMO FBMC, and the algorithms and results in that paper can be tested and verified through POWDER/RENEW.

Researchers

• Hamed Hosseiny
• Brent Kenney