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In a MIMO wireless communications system, a space-time block code specifies how the data symbols are transmitted over different antennas at different time instants. A hybrid space-time code attempts to obtain some of the available diversity and multiplexing gains, achieving low error probability and high data rate. The LD StBc-VBLAST hybrid code layers one spatial-multiplexing antenna (to increase...
By combining the polarized modulation and the spatial modulation technique, dual-polarized spatial modulation (DPSM) has been recently proposed for MIMO transmission to improve the spectral efficiency and reduce the space occupancy. The performance of DPSM over correlated Rayleigh and Rice fading channels has been studied, showing that DPSM technique outperforms uni-polarized SM technique. For a general...
In this paper, an antenna grouping assisted spatial modulation scheme is proposed for massive MIMO systems. Massive multiple-input-multiple-output (MIMO) systems are capable of offering abundant spatial capacity by deploying hundreds of antennas at the base station (BS). Spatial modulation (SM) is one of the key technologies in exploiting spatial capacity, which maps the information bits to the active...
In this paper, we describe a modified signal design for Multistream Spatial Modulation (MSM). The fundamental idea behind MSM is to activate multiple antennas and transmit complex symbols along with active antenna indices. Here, a modified MSM technique explicitly designed to combat the effect of spatial correlation in realistic channel scenarios is proposed. In this MSM scheme, two antennas are made...
In this paper, the measurement results of field experiments for correlation reduction precoding with a repetition code in an overloaded MIMO systems are presented. Measurements are conducted in three propagation conditions that are line-of-sight (LOS), non-line-of- sight (NLOS), and a mobile environment. Numerical results obtained through the measurements show that amplitude shift and phase rotation...
This paper proposes an efficient ordering calculation method employing frequency correlation in multiuser multiple-input multiple-output orthogonal frequency division multiplexing (MU-MIMO-OFDM) Tomlinson Harashima Precoding (THP). Although the ordering process is effective to improve the transmission performance of THP, it requires a large amount of computational effort due to sub-carrier-based operation...
Recently, massive multiple-input multiple-output (MIMO) systems have attracted considerable research interest and have been regarded as a candidate technology for the 5th generation (5G) cellular networks. In massive MIMO systems, a base station (BS) is equipped with a large number of antennas which are serving several simultaneous single antenna users. An increasing number of antennas is difficult...
Antenna correlation is prevalent in higher frequencies as well as in massive MIMO, thus the study of correlated MIMO broadcast channels is becoming a subject of increasing interest. This paper explores the fundamental limits of such systems, focusing on cases where correlation eigenspaces are neither independent nor identical, so that known beam-space division techniques do not directly apply. We...
In this paper, an effective low complexity generalized spatial modulation (GenSM) scheme with transmit antenna grouping is proposed for massive multi-input multi-output (MIMO) system to deal with the channel correlation among transmit antennas. In the proposed scheme, all transmit antennas are divided into several equal-sized groups, and spatial modulation (SM) is carried out to select one active...
Transmit antenna selection (TAS) schemes have been adopted in various communication systems to provide improved performance with relatively reduced complexity. The quality-of-service (QoS) in these systems depends on the availability of perfect channel state information (CSI). In practice, it is difficult to acquire perfect CSI, since it may get outdated due to feedback process. In this paper, we...
Radio environment maps are geographical maps with overlaid performance information of radio communication systems, that can be considered as one of the key enablers for self-organizing networks. After the introduction of Minimization of Drive Tests (MDT) to the standards, operators are interested to generate radio environment maps based on sparse sets of MDT measurements gathered from user equipment...
In this paper, we shall develop a generic channel estimation framework based on the convex formulation for dense cloud radio access networks (Cloud-RAN). Due to the training resource constraint and the large number of transmit antennas, the pilot length is smaller than the antenna number, and thus channel estimation becomes an ill-posed inverse problem. By observing that the wireless channel possesses...
Massive Multiple-Input Multiple-Output (MIMO) is an emerging technology for the future 5G wireless communication systems and has been expected to dramatically improve the performance over the years. The main aim of this paper is to investigate the ergodic capacity of the downlink massive Multi-User (MU-MIMO) system under spatially correlated Rayleigh fading channels using two correlative models, namely...
A realistic stochastic multiple-input multiple-output (MIMO) channel is presented in this paper. It is shown that the spatial correlation depends on the statistical properties of the channel, the antenna pattern, the inter-element spacing and the array configuration. Furthermore, the total spatial correlation matrix is equal to the Kronecker product of the transmit and receive correlation matrices...
This paper describes a novel method for the measurement of the frequency response of the indoor RF propagation channel utilizing an HP network analyzer. Preliminary measurements of the frequency response of the channel in the frequency bands 900–1000MHz and 1.6–1.8GHz are reported. These measurements determine the dependence of the rms excess delay time on the separation between the transmitting and...
The authors have proposed a method of estimating the location of the receiving terminal by a triangulation technique using DOD information from the multiple transmitters, which is calculated only from the Received Signal Strength Indicator (RSSI). In our previous study, DODs are calculated using four beacon signals, but the number of the antennas for each array is limited to two, which offers insufficient...
Multiuser multiple-input multiple-output (MU-MIMO) has been much attracted much attention for improving the spectral efficiency within a limited frequency band. However, it is not possible to communicate with the users that exceed the number of base station (BS) antennas in the MU-MIMO transmission. We have proposed a method by using non orthogonal multiple access (NOMA) and Zero Forcing (ZF) at the...
We examine for the first time the impact of transmitter-side correlation on the secure transmission with artificial noise (AN), based on which a new power allocation strategy for AN is devised for physical layer security enhancement. Specifically, we design a correlation-based power allocation (CPA) for AN, of which the optimality in terms of achieving the minimum secrecy outage probability is analytically...
Channel estimation is a major overhead factor in large-scale multiple-input multiple-output \mbox{(MIMO)} systems, especially under the high- speed railway scenarios. This paper proposes a position-aided channel estimation scheme for high- speed railway communication systems, where both the transmitter and the receiver are equipped with large-scale antenna linear arrays. By joint spatio- temporal...
This paper presents an optimal transmit antenna selection technique to enhance the channel capacity in the case of high signal-to-noise ratio (SNR) multiple-input and multiple-output (MIMO) downlink correlated channel. Most related work has thus far considered optimal antenna selection technique with uncorrelated MIMO channel to reduce radio frequency (RF) module cost. Thus, we propose an optimal...
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