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In this paper we present a joint precoded and windowed OFDM system. This new hybrid method provides flexibility to suppress the out-of band (OOB) emission in non-contiguous OFDM systems used in cognitive radio. This method also provides the possibility of shortening the cyclic prefix without sacrificing the OOB emission or increasing the additional interference which is the case in low-latency future...
In cellular mobile communication systems, the co- channel inter-cell interference (ICI) remains as a critical barrier to achieving further improvement in spectrum efficiency. As an approach to controlling downlink ICI, multi-cell coordinated MU-MIMO has been actively discussed in many papers. In multi-cell coordinated MU-MIMO, the simultaneous transmission for multiple mobile stations is made possible...
Linear index coding can be formulated as an interference alignment problem, in which precoding vectors of the minimum possible length are to be assigned to the messages in such a way that the precoding vector of a demand (at some receiver) is independent of the space of the interference (non side-information) precoding vectors. An index code has rate 1/l if the assigned vectors are of length l. In...
This work1 analyzes the Generalized Degrees-of-Freedom (GDoF) of the 2-User Multiple-Input Single-Output (MISO) Broadcast Channel (BC) in the so-called Distributed CSIT regime, with application to decentralized wireless networks. This regime differs from the classical limited CSIT one in that the CSIT is not just noisy but also imperfectly shared across the transmitters (TXs). Hence, each TX precodes...
Recent advances in interference exploitation showed that exploiting knowledge of interference constructively can improve the receive signal-to-interference and noise ratio (SINR) at the destination. This paper exploits this concept to design artificial noise (AN) beamformers constructive to the intended receiver (IR) yet keeping AN disruptive to possible eavesdroppers (Eves). A multiple-input single-output...
In this paper, we consider precoder design for multiuser multiple-input-multiple-output (MIMO) Gaussian broadcast (BC) channels and propose a generalized zero-forcing (GZF) precoder based on successive dirty-paper coding (DPC), i.e., the GZF-DP precoder. The GZF-DP precoder is an extension of the GZF-DP precoder designed earlier for multi-input-single-output broadcast (MISO-BC) channels, and also...
This paper presents an application-specific instruction-set processor (ASIP) for multiuser multiple-input multiple-output (MU-MIMO) broadcast precoding. The ASIP is designed for a base station (BS) with four antennas to perform user scheduling and precoding. Transport triggered architecture (TTA) is used as the processor template and high level language is used to program the ASIP. Several special...
Dynamic time-division duplexing (TDD) is considered a promising solution to deal with fast-varying traffic often found in ultra-densely deployed networks. At the same time, it generates more interference which may degrade the performance of some user equipment (UE). When base station (BS) utilization is low, some BSs may not have an UE to serve. Rather than going into sleep mode, the idle BSs can...
Spectrally precoded OFDM is a recent approach that aims for the suppression of the OOB, as well as the in-band gap, emissions in OFDM systems. Theoretically, the technique shows High suppression of the OOB and the in-band gap emissions. Although, practically hardware impairments may limit the precoder's performance. Yet, this demonstration shows that despite the hardware impairments, implemented spectrally...
Despite the promising benefits of the cloud-radio access network (C-RAN), the fronthaul (FH) imposes stringent requirements in terms of data rate, latency, jitter and synchronisation. In the classical C-RAN, the FH capacity scales linearly with the number of the transmitting antennas, which has posed severe demands on the FH capacity, especially due to emerging 5G technologies such as massive MIMO...
Nonlinear power amplifiers distort the transmitted signal and out-of-band (OOB) radiation becomes a source of interference for users operating in adjacent channels. This paper studies the effect of Massive Multiple Input Multiple Output (MIMO) system on the OOB interference. Massive MIMO relies on channel based precoding which ensures the signal is added constructively at the receiver user equipment...
Vehicles are the third fastest growing connected device type after smart phones and tablets. Also, automotive industry is interested to get more vehicles connected to the internet to improve traffic safety and efficiency. This creates a need for Vehicle-to-Everything (V2X) communications. In this work, the possibility of exploiting beamforming in LTE-V2X is considered. Singular value decomposition...
Multi-User Multiple Input Multiple Output (MU-MIMO) enables a multi-antenna access point (AP) to serve multiple users simultaneously, and has been adopted as the IEEE 802.11ac standard. While several PHY-MAC designs have recently been proposed to improve the throughput performance of a MU-MIMO WLAN, they, however, usually assume that all the concurrent streams are of roughly equal length. In reality,...
In this paper, we study the power allocation and power splitting problem for simultaneous wireless information and power transfer (SWIPT) in a multi-user MISO broadcast system, in which there are two types of single-antenna users: traditional users that only receive information and modern users that receive information and energy simultaneously from a multi-antenna base station via power splitting...
We derive the asymptotic secrecy sum-rate of block diagonalization (BD) precoding for physical layer security in downlink multi-user wireless networks using artificial noise (AN). We first derive the secrecy sum-rate assuming that the channel of the eavesdropper is not known at the transmitter and then the asymptotic secrecy sum-rate is derived. The optimum power allocation for asymptotic secrecy...
Real interference alignment is efficient in breaking-up a one-dimensional space over time-invariant channels into fractional dimensions. As such, multiple symbols can be simultaneously transmitted with fractional degrees-of-freedom (DoF). Of particular interest is when the one dimensional space is partitioned into two fractional dimensions. In such scenario, the interfering signals are confined to...
This paper examines design of mixed-timescale hybrid precoding with vector perturbation (VP) to achieve minimum mean square errors (MMSE) for multi-user massive multiple-input multiple-output (MIMO) systems. In particular, equipped with the perfect effective channel state information (CSI)-based MMSE-VP solution at the baseband, we derive partial CSI-based linear radio frequency (RF) precoding as...
Visible light communication (VLC) is an emerging technique that uses light-emitting diodes (LED) to combine communication and illumination. It is considered as a promising scheme for indoor wireless communication that can be deployed at reduced costs while offering high data rate performance. In this paper, we focus on the design of the downlink of a multi-user VLC system. Inherent to multi-user systems...
We consider nonlinear transceiver design for downlink multiuser multi-antenna secure communications with an external multi-antenna eavesdropper. The multi-antenna transmitter simultaneously transmits confidential-message-bearing signals and artificial noise (AN) using nonlinear Tomlinson Harashima precoding based on the limited channel state information feedback. For the proposed nonlinear secure...
We consider a hybrid eavesdropping wireless system, where the locations of the eavesdroppers are drawn from Poisson point process (PPP). The eavesdroppers work in a half-duplex mode with a certain probability to transfer from eavesdropping mode to jamming mode. Based on the stochastic geometry (SG) and the random matrix theory (RMT), we derive the analytic results for the secrecy outage probability...
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