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Transmitter (TX) cooperation at various levels has been shown to increase the sum throughput of multiuser multiple-input multiple-output (MIMO) systems. In this paper we consider a k-user MIMO system where TXs have only global channel state knowledge. It has been theoretically shown that interference alignment (IA) achieves the K/2 degrees of freedom of this K-user MIMO interference channel. However,...
In this paper, we propose two complexity reduction techniques for blind adaptive beamforming in orthogonal frequency division multiplexing (OFDM) antenna array systems. For each sub-carrier, a beamformer with generalized sidelobe canceller (GSC) structure is designed according to the constrained constant modulus (CCM) criterion with weight vectors adaptation based on the recursive least squares (RLS)...
Adaptive array signal processing is widely used to improve anti-jamming capability for satellite navigation receivers. Robust beamforming approaches based on steering vector uncertainties, which have been proposed in recent years, have better performance than standard minimum variance distortionless response (MVDR) beamformer in space adaptive processing (SAP). In some practice applications, the attitude...
In this paper, we study bit allocation and pairing methods based on zero forcing beamforming for downlink multiuser distributed antenna systems with limited feedback. Before assigning the feedback bit for each distributed antenna (DA) port, we need to solve the pairing issue which determines the set of DA ports to support a user. To this end, we first analyze an upper bound of a mean rate loss between...
Smart antenna is a system based on the antenna elements which are distributed uniformly as array and on the beamformig (BF) algorithm. Each element in the array receives the wave plane signals individually, and then, the beamformer tries to produce the optimum weight for each element with respect to the reference element in the array. This technique is called beamformig. MVDR is one of the most important...
In order to solve the problem that most of the directions-of-arrival (DOA) algorithms are based on the prior knowledge of source number and the estimation error of source number leads to the degradation of DOA algorithm performance, a conformal array DOA algorithm with unknown source number is proposed. This method is realized by introducing the pseudo expected signal. The optimum weight deduced by...
This paper presents the theoretical capacity performance of different linear multi-user MIMO (MU-MIMO) pre-coding algorithms for a millimeter wave communication system using hybrid beam-forming. Hybrid beam-forming uses both RF and digital beam-forming and is a practical way to achieve the required array gains when the high bandwidths available at millimeter wave frequencies are utilized. The performances...
In this paper, we address the effects of radio frequency (RF) transceiver in-phase/quadrature-phase (I/Q) imbalance in transmission systems which are utilizing orthogonal frequency-division multiplexing (OFDM) waveforms. Special emphasis is on the analysis of external interference sources and their mitigation with receiver antenna array processing, assuming independent fading for the antenna elements...
In this paper, an adaptive antenna arrays processing based on Sample Matrix Inversion (SMI) algorithm with a novel training scheme is presented. The training scheme used is known as distributed training scheme [1]. The scheme uses distributed placement of the training symbols throughout the packet. The channel estimation, along with this particular training scheme, is designed to track intermittent...
Power consumption and costs of the analog front-end (AFE) chains are often not negligible for large-scale antenna array systems. A low-complexity hardware architecture is to use a number of AFE chains that is less than the number of the antennas. Beamforming for this low-complexity hardware architecture involves both digital and analog beamforming, which is termed hybrid analog/digital beamforming...
The downlink of a coordinated multi-cell distributed antenna system is considered. In [1], coordinated port selection was shown to achieve significant performance gains. However, in the system considered therein, the ports in each cell were constrained to transmit only to user terminals (UTs) in that cell. In this work, we consider a generalization of the problem considered in [1] by alleviating this...
Recently, a technique entitled “Blind Interference Alignment (BIA)” was proposed, which allows interference to be aligned within a reduced subspace without knowledge of the channel state information at the transmitter. The key to realizing the BIA scheme is the use of a receive antenna that is capable of switching among multiple channel-states (with channel diversity) in a pre-determined way. In this...
Herein, we study transmit beamforming techniques in an underlay cognitive mode for the coexistence of satellite and terrestrial networks with the satellite forward link as primary and the terrestrial downlink as secondary. Since geostationary satellite terminals have predetermined propagation characteristics so that they always point towards the geostationary satellite, the interference received by...
Conventional spatial-based array processing technique requires a lot of large storage space and costly hardware implementations in an antenna array-based global navigation satellite system (GNSS) receivers. In this paper, the compressive sensing (CS)-based antenna array processing scheme is proposed to apply in anti-jamming GNSS receivers. The design criteria of CS matrix is to meet the restricted...
This paper investigates the performance of spacedivision multiple access (SDMA) schemes in cognitive radio systems (CR) with multiple primary users (PUs) and secondary users (SUs) sharing the same spectrum. By adding more constraints to the conventional SDMA schemes and using the optimization of the Lagrange multipliers we developed an iterative weights calculating method to determine the new cognitive...
We consider downlink cellular multi-user communication between a base station (BS) having N antennas and M single-antenna users, i.e., an N × M Gaussian Broadcast Channel (GBC). Under an average only total transmit power constraint (APC), large antenna arrays at the BS (having tens to a few hundred antennas) have been recently shown to achieve remarkable multi-user interference (MUI) suppression with...
This paper investigates a hybrid analog/digital beam former (ADBF). Traditional analog beam formers (ABF) steer a single beam using a single transceiver, power splitter/combiner, and electronically controlled analog phase shifters. In contrast modern digital beam formed arrays (DBF) or ‘smart antennas’ use separate transceiver chains, A/D and D/A converters, and DSPs. This enables direct digital control...
This paper proposed a measurement method of interferences suppression for on-site radiation emission test. This method firstly acquires the multi-channel receiving data, then the DOA of EUT radiated signal and other interference signals can be achieved by MUSIC spatial spectrum estimation technique. And MVDR beam-forming algorithm was taken to form the beam pattern nulls in the direction of the interference...
In this paper, we address the problem of severe performance degradation of cell-edge users in conventional cellular networks via multicell processing with improved spectral efficiency. Using uplink-downlink duality, we propose an iterative multicell beamforming algorithm that minimises the total transmit power within a virtual cell of 3 adjacent sectors of 3 neighbouring BSs. We derive and employ...
This paper presents and describes a low-cost hardware implementation of smart antenna based on FPGA. Unlike systems using high-cost devices, the case herein uses a low-end FPGA for beamforming algorithm implementation, enabling smart antenna applications in practical and commercial problems, as for instance interference mitigation. The low-cost smart antenna array underwent two different types of...
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