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Massive-Multi Input and Multi Output (MIMO) antenna system is considered as the key technology to improve both spectral efficiency (SE) and energy efficiency (EE) for 5G systems. Where pilot contamination and inter-cell interference have been considered as basic limiting factors to achieve high data rate. These parameters will saturate the SE and truncate to a constant value. In this work, we explore...
Filterbank Multicarrier (FBMC) has been proposed as an alternative to Orthogonal Frequency Division Multiplexing (OFDM) in the multicarrier modulation scenario. One of the many advantages of OFDM is its compatibility with Multi-Input Multi-Output (MIMO) systems. One disadvantage of using FBMC is the need for multi-tap per subcarrier equalization, unlike the single tap equalization in OFDM. There has...
We present a composite suite of technologies for spectral coexistence of existing communication and radar systems using the Xampling framework. For a stand-alone communication system, we consider a cognitive radio (CRo) that receives multiband signals with unknown carrier frequencies and directions of arrival, and demonstrate joint spectrum sensing via CompreSsed CArrier and Direction-ofarrival Estimation...
The increase in the number of degrees of freedoms (DoF) that is afforded by multiple-input-multiple-output (MIMO) phased arrays is accompanied by an increase in hardware and computational costs. We mitigate this problem in a collocated MIMO phased array system by employing a selection strategy where a subset of K transmitter-receiver (Tx-Rx) pairs is chosen from the availableN pairs. We formulate...
Next-generation wireless networks are expected to support exponentially increasing number of users and demands of data, which all rely on the essential media: spectrum. Notice that the 5G networks are featured either by wide bandwidth like mmWave systems, or by large-scale antennas like massive MIMO. We find those two trends, together with waveforming or beamforming, can lead to a common phenomenon:...
Performance of OFDM (Orthogonal Frequency Division Multiplexing) systems is limited by inter carrier interference (ICI) under high Doppler scenarios such as that encountered in high speed trains like TGV. The use of multiple receive antennas is known to be a very effective way to combat ICI. In a recent publication, the authors explored the use of transmit (Tx) antennas for ICI mitigation. It considered...
We consider the problem of designing hybrid analog-digital beamformers in a downlink multi-user large-scale MIMO system. The objective is to minimize the total transmit power, while fulfilling SINR targets of all users. A dual virtual uplink problem is formulated for the original downlink problem based on the uplink-downlink duality theory, in order to decouple the digital beamformers in the constraints...
In this paper, the self-interference mitigation performance of in-band full-duplex multiple-input multiple-output (MIMO) nodes is considered in the context of models for realistic hardware characteristics in which antennas are reused to transmit and receive simultaneously. The use of MIMO indicates a self-interference channel with spatially diverse inputs and outputs. Consequently, there are both...
We design jamming resistant receivers to enhance the robustness of a massive MIMO uplink channel against jamming. In the pilot phase, we estimate not only the desired channel, but also the jamming channel by exploiting purposely unused pilot sequences. The jamming channel estimate is used to construct the linear receive filter to reduce impact that jamming has on the achievable rates. The performance...
In this paper, we consider a decode-and-forward (DF) full-duplex relay (FDR)-aided downlink wireless communication system consisting of one base station (BS) equipped with large scale antennas and multiple MIMO FDRs, which have been recognized as essential techniques in the fifth generation (5G) wireless communications. In view of the system performance not only limited by self-interference (SI) and...
This paper considers practical deployment issues of a multi-user MIMO system with full-duplex (FD) base station and half-duplex (HD) user equipment. The aim is to select a set of uplink (UL) and downlink (DL) users at any instant that will provide a satisfactory performance in system resource allocation. Furthermore, it is also necessary to deal with the interference created by the UL users to the...
The achievable degree of freedom (DoF) boosting has been demonstrated on a single-input single-output (SISO) X channel by using outdated and instantaneous channel state information at transmitter (CSIT) synergistically, in contrast to that of using completely outdated CSIT. However, the means by which the DoF gain can be obtained in a multiple-input multiple-output (MIMO) system remains unclear. This...
In massive multiple-input multiple-output (MIMO) systems, superimposed (SP) and time-multiplexed (TM) pilots exhibit a complementary behavior, with the former and latter schemes offering a higher throughput in high and low inter-cell interference scenarios, respectively. Based on this observation, in this paper, we propose an algorithm for partitioning users into two disjoint sets comprising users...
This paper investigates the problem of interference among the simultaneous multiuser transmissions in the downlink of multiple antennas systems. Symbol-level precoding (SLP) is a promising technique which has recently demonstrated large performance gains over the conventional block-level techniques. These gains can be translated in lower power requirements, improved energy efficiency, lower peak to...
This paper presents an FPGA-based prototype of the dual link algorithm that maximize the achievable weighted sum rate for MIMO interference network. The iterative algorithm is fast monotone convergent but it must be completed quickly through pilot signaling. Therefore we propose an FPGA-based implementation, targeting software defined radio (SDR) platforms, that is designed to rapidly process the...
We propose an architecture that incorporates a robust and agile primary user (PU) detection, accompanied by a dynamic OFDM spectrum allocation scheme. By exploiting the capabilities of a 2×2 MIMO PCIe SDR device we are able to maximize the usage of the available spectrum with the minimal PU disturbance.
The performance of multiuser multiple input multiple output (MIMO) downlink communication system is degraded under the assumption of rapid movement of user terminals with a certain speed. Though several methods have been proposed to improve this situation, they consume extra-degrees of freedom for the extension of the zero forcing (ZF) area and/or heavy computational load for the frequent update of...
In recent years, several progresses have been made in belief propagation (BP) based signal detection with large scale factor graphs. When we apply the BP algorithm to equalization in a SIMO multipath channel, the factor graph has many short loops where the edge strengths have a fixed pattern. Thus, the proper convergence is not always expected. In general, the LLR oscillates in ill-converged cases...
Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is known as a high capacity system for data transmission over broadband wireless communication channels. However, the time-varying fading and Doppler effect of the underwater acoustic channel can destroy the orthogonality of subcarriers, causing intercarrier interference (ICI). In this paper, we proposed a combined...
In this paper, we propose the new scheme, multi-user full-duplex MIMO (Multiple-Input and Multiple-Output) system, which performs uplink and downlink signal transmissions at the same frequency and time between the base station and multiple terminals. We show the characteristics of the transmission capacity of the proposed full duplex MIMO system by use of the channel information measured in an actual...
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