Wireless LAN White Papers
Spherical Linear Interpolation for Transmit Beamforming in MIMO-OFDM Systems With Limited Feedback
Overview Transmit beamforming and receive combining can be simply implemented over frequency selective channels by using Multiple-Input Multiple-Output (MIMO) technology combined with Orthogonal Frequency Division Multiplexing (OFDM) in what is known as MIMO-OFDM. Generally this requires knowledge of the transmit beamforming vectors for every tone at the transmitter. In systems without reciprocity between the uplink and the downlink channels, this requires informing the transmitter about all the beamforming vectors through a feedback control channel. To reduce the feedback required, this paper proposes to exploit channel coherence to send back only a fraction of the beamforming vectors. The coherence of the transmit beamforming vectors is established. A new spherical interpolator, with an additional parameter for phase rotation, is proposed to fill in the gaps between known vectors.
| Publisher | University of Texas | File Format | |
|---|---|---|---|
| Date Published | December 2004 | ||
| Format | White Papers | ||
| Topics | |||
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