3,842 research outputs found
PAR-Aware Large-Scale Multi-User MIMO-OFDM Downlink
We investigate an orthogonal frequency-division multiplexing (OFDM)-based
downlink transmission scheme for large-scale multi-user (MU) multiple-input
multiple-output (MIMO) wireless systems. The use of OFDM causes a high
peak-to-average (power) ratio (PAR), which necessitates expensive and
power-inefficient radio-frequency (RF) components at the base station. In this
paper, we present a novel downlink transmission scheme, which exploits the
massive degrees-of-freedom available in large-scale MU-MIMO-OFDM systems to
achieve low PAR. Specifically, we propose to jointly perform MU precoding, OFDM
modulation, and PAR reduction by solving a convex optimization problem. We
develop a corresponding fast iterative truncation algorithm (FITRA) and show
numerical results to demonstrate tremendous PAR-reduction capabilities. The
significantly reduced linearity requirements eventually enable the use of
low-cost RF components for the large-scale MU-MIMO-OFDM downlink.Comment: To appear in IEEE Journal on Selected Areas in Communication
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Spatial data stream multiplexing scheme for high-throughput WLANs
A novel scheme using spatial data stream multiplexing (SDSM) in the upcoming multiple-input multipleoutput (MIMO)-based IEEE 802.11n physical layer is proposed. It is shown that with SDSM, the same data rate can be achieved by using less number of transmit and receive antennas and therefore this scheme can reduce the number of antennas which results in reducing mutual coupling effects, hardware costs and implementation complexities. The maximum data rates that can be achieved using a 2 * 2 MIMO system is 270 Mbps and for a 4 * 4 MIMO system is 540 Mbps. The same data rates can be achieved using the SDSM technique which reduces the 2 * 2 MIMO system to 1 * 1 SISO system and the 4 * 4 MIMO system to a 2 * 2 MIMO system
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Future transmitter/receiver diversity schemes in broadcast wireless networks
An open diversity architecture for a cooperating broadcast wireless network is presented that exploits the strengths of the existing digital broadcast standards. Different diversity techniques for broadcast networks that will minimize the complexity of broadcast systems and improve received SNR of broadcast signals are described. Resulting digital broadcast networks could require fewer transmitter sites and thus be more cost-effective with less environmental impact. Transmit diversity is particularly investigated since it obviates the major disadvantage of receive diversity being the difficulty of locating two receive antennas far enough apart in a small mobile device. The schemes examined here are compatible with existing broadcast and cellular telecom standards and can be incorporated into existing systems without change
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