Retrospective Interference Alignment for Two-Cell Uplink MIMO Cellular Networks with Delayed CSIT

In this paper, we propose a new retrospective interference alignment for two-cell multiple-input multiple-output (MIMO) interfering multiple access channels (IMAC) with the delayed channel state information at the transmitters (CSIT). It is shown that having delayed CSIT can strictly increase the sum-DoF compared to the case of no CSIT. The key idea is to align multiple interfering signals from adjacent cells onto a small dimensional subspace over time by fully exploiting the previously received signals as side information with outdated CSIT in a distributed manner. Remarkably, we show that the retrospective interference alignment can achieve the optimal sum-DoF in the context of two-cell two-user scenario by providing a new outer bound.Comment: 7 pages, 2 figures, to appear in IEEE ICC 201

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Estimation of Maximum Speed-Up in Multicore-Based Mobile Devices

This letter proposes an effective speed-up estimation method for modern mobile devices. Unlike existing approaches, the proposed method uses a task graph to extract multiple parallelizable fractions of real-world mobile scenarios. Then, it uses the extracted parallelizable fractions to estimate the theoretical maximum speed-up of mobile devices. In experiments, the proposed method estimated the maximum speed-up of mobile devices more accurately than the state-of-the-art speed-up estimation method.11Nsciescopu

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Joint Modulation and Beamforming for MIMO Systems with 1-bit DACs

International audienceTo realize multiple-input multiple-output (MIMO)with low cost and power consumption, the use of low-resolutiondigital-to-analog converters (DAC) is drawing significant interest.While previous studies on massive MIMO systems with low resolutionDACs have focused on optimizing precoding, thisapproach faces the limitation that the coarse resolution at thetransmitter makes it difficult to generate the transmit signal closeenough to the desired one when a small scale MIMO transmitteris considered as in IoT networks. To address this problem, wepropose a new transmission framework that jointly performsmodulation and beamforming. With the proposed scheme, themessage symbol is directly mapped into a feasible transmit vector.We also develop a channel-adaptive mapping function for theproposed framework that minimizes error probability. Simulationresults show that the proposed scheme can improve the errorperformanc

Retrospective Interference Alignment for MIMO Cellular Networks with Delayed CSIT

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