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In this paper, a secure communication system model for massive multiple-input multiple-output (MIMO) relay networks is investigated. Specifically, physical layer secure transmission is provisioned in multi-user relay networks by employing massive MIMO, linear precoder/detectors and artificial noise generation in the presence of a passive multi-antenna eavesdropper. In particular, the achievable asymptotic...
The Licensed Shared Access (LSA) approach has emerged as a viable solution to provide dynamic spectrum access by allowing the primary users (incumbents) to temporarily lease the access to their spectrum to third parties (licensees). Recently, there have been proposals in Europe and USA to share radar bands (2.3 GHz in Europe, 3.5 GHz in USA) for commercial broadband use. This paper studies the problem...
For single-cell multi-user massive multi-input-multi-output (MIMO) system downlink, we consider the per-antenna power constraint and propose a modified maximum-ratio-transmission (MRT) precoding scheme. The outage probability performance of the scheme are analyzed. To enable the analysis, we study the random behaviour of the signal-to-interference-plus-noise-ratio (SINR) and derive an approximation...
In this paper, the energy harvesting (EH) technique is investigated by designing transceivers for a K link multiple-input multiple-output (MIMO) interference channel. Each link consists of two full-duplex (FD) nodes exchanging information simultaneously in a bi-directional communication technique. All the nodes suffer interference, such as strong self-interference because of operating the FD mode...
This paper investigates user throughput improvement by transmitter-side three-dimensional (3D) beamforming, which operates in both azimuth and elevation antenna domains. Focusing on user-specific elevation beamforming, we describe the user throughput by means of system-level computer simulation using typical LTE/LTE-Advanced system parameters. Preliminary simulation results for average and 5-percentile...
We present a new multiple-input-multiple-output (MIMO) transmission scheme for generic phase-shift-keying (PSK) modulations in the multi-user (MU) downlink channel, where Constant Envelope Precoding (CEP) is combined with concepts of interference exploitation. In the proposed approach, multi-user-interference (MUI) is treated as a resource for increasing the signal-to-interference-and-noise-ratio...
The 2 user MIMO interference channel with arbitrary antenna configurations is studied under arbitrary levels of partial CSIT for each of the channels, to find the degrees of freedom (DoF) achievable by User 2 while User 1 achieves his full interference-free DoF. The goal is to gain new insights due to the inclusion of MIMO (multiple antennas at both transmitters and receivers) into the signal space...
In this article, we propose a receiver chain alignment (RCA) method to evaluate the degrees of freedom (DoF) of symmetric three-user multiple input multiple output (MIMO) interference channel (IC). The interference observed at the adjacent receivers is represented in a chain of optimal overlap subspaces, the dimension of which is determined merely by the topological information (antennas sharing)...
Single-User Multiple-Input Multiple-Output (MIMO) transmissions are possible since Rel. 10 of 3GPP LTE-A. The Closed Loop Spatial Multiplexing (CLSM) transmission mode enables up to a four fold increase in spectral efficiency compared to Rel. 8, yet it requires complex User Equipment (UE) hardware supporting more than one transmit antenna. The closed loop spatial multiplexing transmission mode enables...
Relaying is one of the promising approaches for extending service coverage and improving quality of service. The self-backhauling of relays towards a serving (donor) eNode B provides cost-effective solution for deployment scenarios where conventional backhauling is either costly or unavailable. The end-to-end throughputs achievable by users served by relays are dependent on achievable throughputs...
We introduce the concept of Polarimetrie interference-alignment (PIA) beamforming for multiuser MIMO channels. By using vector antennas, we harness the orthogonal polarization components of electromagnetic waves to provide a signal space for the interference-alignment technique proposed by Cadambe and Jafar. We show that such beamformer exists and provide preliminary comments regarding its operation...
While spectrum at millimeter wave (mmWave) frequencies is less scarce than at traditional frequencies below 6 GHz, still it is not unlimited, in particular if we consider the requirements from other services using the same band and the need to license mmWave bands to multiple mobile operators. Therefore, an efficient spectrum access scheme is critical to harvest the maximum benefit from emerging mmWave...
Self-Organizing Networks (SON) is an advancing technology in wireless communication systems, which employs various algorithms to improve the network performance and reduce the network maintenance cost. The SON is an integral part of the Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) standard. The SON processing can be centralized, distributed or a hybrid of these two schemes...
We consider a two-user multiple-input multiple-output (MIMO) multiple access wiretap channel with N antennas at each transmitter, N antennas at the legitimate receiver, and K antennas at the eavesdropper. We determine the optimal sum secure degrees of freedom (s.d.o.f.) when the channel gains are fixed for the duration of the communication. We provide optimal achievable schemes based on a combination...
In this paper, we analyze the spectral efficiency (SE) and energy efficiency (EE) of multi-user (MU) multiple-input and multiple-output (MIMO) in multi-cell downlink networks. We first analyze the achievable sum-rate, i.e., the SE, of MU-MIMO systems with maximal ratio transmission (MRT) and zero-forcing (ZF) precoders in downlink cellular networks. Different from the conventional analysis, we derive...
We consider the physical layer security for the downlink system, where the confidential messages can be wiretapped by both the intended users (IUs) and the external eavesdroppers (EEs). Regularized channel inversion (RCI) precoding is adopted for multiuser communication because it can control the mutual information leakage among users. And, to enhance the secrecy performance, artificial noise (AN)...
In this paper, a new cooperative spectrum sharing protocol which avoids mutual interference between primary and secondary users by employing spatial modulation (SM) at the secondary transmitter (ST), is proposed for overlay cognitive radio networks. In the proposed protocol, ST cooperates with selective decode-and-forward (DF) relaying strategy to prevent error propagation. Primary transmitter (PT)...
We consider Mx2 X channels with M+1 antennas at each node. The proposed scheme achieves both the optimal degrees of freedom (DoF) of 2M for the considered channel and the diversity order of 2 simultaneously. The key to achieving them is to design beamformers using interference alignment (IA) scheme with Alamouti codes. Furthermore, the proposed scheme requires 2 symbol extensions. We assume that each...
In this paper, downlink transmission schemes that are able to improve the energy efficiency of multi-cell massive distributed antenna systems (DAS) are investigated. We employ a power consumption model by considering the transmit power, the backhaul power, the uplink pilot transmit power and the circuit power, in contrast to existing works which focus on co-located antenna systems where the backhaul...
The Multiuser Multiple-Input Multiple-Output (MU-MIMO) has been much attracted much attention for improving the spectral efficiency within a limited frequency band. The MU-MIMO techniques have been introduced in the standardization of IEEE802.11ac and LTE-Advanced. However, it is not possible to communicate with the users that exceed the number of base station (BS) antennas in the MU-MIMO transmission...
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