Multiple-input Multiple-output Nodes Research Articles

Joint Analog and Digital Transceiver Design for Wideband Full Duplex MIMO Systems

In this paper, we propose a wideband Full Duplex (FD) Multiple-Input Multiple-Output (MIMO) communication system comprising of an FD MIMO node simultaneously communicating with two multi-antenna UpLink (UL) and DownLink (DL) nodes utilizing the same time and frequency resources. To suppress the strong Self-Interference (SI) signal due to simultaneous transmission and reception in FD MIMO systems, we propose a joint design of Analog and Digital (A/D) cancellation as well as transmit and receive beamforming capitalizing on baseband Orthogonal Frequency-Division Multiplexing (OFDM) signal modeling. Considering practical transmitter impairments, we present a multi-tap wideband analog canceller architecture whose number of taps does not scale with the number of transceiver antennas and multipath SI components. We also propose a novel adaptive digital cancellation based on truncated singular value decomposition that reduces the residual SI signal estimation parameters. To maximize the FD sum rate, a joint optimization framework is presented for A/D cancellation and digital beamforming. Finally, our extensive waveform simulation results demonstrate that the proposed wideband FD MIMO design exhibits higher SI cancellation capability with reduced complexity compared to existing cancellation techniques, resulting in improved achievable rate performance.

Route Discovery Protocol for Energy Efficient Networks With MIMO Links

We propose a reactive route discovery protocol for energy efficient transmission in a wireless multihop network with multiple input multiple output (MIMO) channels. We focus on networks consisting of MIMO nodes that use time division scheduling where the source needs to transmit a certain amount of data to the destination in a fixed amount of time. We show how the intermediate nodes find the route distributively. This protocol takes into account the quality of the MIMO channels and allocates power to them so that the end-to-end transmission energy is minimized. The resulting protocol is easy to implement and provides the most energy efficient route and the power allocation for the data transmission. We perform simulations on Rayleigh-fading channels to show the significant energy benefits of the proposed route discovery protocol against a dynamic source routing (DSR)-based routing protocol with optimal power allocation.

Power allocation for two different traffics in layered MIMO systems

In multiple input multiple output (MIMO) relay networks, an MIMO node can relay different traffics from multiple MIMO source nodes. Thus, an MIMO relay node has to allocate the power across multiple channels to relay different traffics. In this paper, we consider the power allocation across multiple layers of MIMO channel when two different traffics, real-time and best-effort traffics, are presented. Generally, realtime traffics have stringent delay constraints and their data streams could not be multiplexed with the data streams from best-effort traffics due to different quality of service (QoS). Since MIMO channels can provide multiple parallel channels, we are able to transmit both different traffics separately (and simultaneously). For efficient power use, we investigate the power allocation across multiple parallel channels in presence of two different traffics with different performance index for each traffic. Performance analysis is carried out for uncorrelated Rayleigh-fading MIMO channels.