In this correspondence, we investigate the performance of a multi-cell multiple-input multiple-output downlink (DL) system aided by base station (BS) cooperation, relay cooperation, and polarization-multiplexing (PM). Triply-polarized antennas that are employed at the BSs, relays, and mobile stations (MSs) to conceive PM serve as an replacement for multiple uni-polarized antennas that inflict space limitation. In a multi-user multi-cell relay-aided scenario, MSs and relays conflict multi-user interference (MUI) as well as inter-cell or co-channel interference (CCI). Furthermore, the MSs experience intra-relay interference and inter-relay interference. In this paper, both the MUI and CCI at the relays are completely removed by the combined preprocessing operated at the BS. Similarly, the intra-relay and inter-relay interference are eliminated with the aid of the joint preprocessing operated at the relays. Specifically, in this contribution, the performance of the considered system is investigated when the channel state information (CSI) required at the BSs to implement the joint preprocessing suffers from feedback and back-haul delays. In our contribution, feedback channels that convey the CSI to the BSs endure noise and fading as well. Our simulation study demonstrates that the use of triply polarized antennas in combination with joint preprocessing at the BSs and relays can be regarded as an efficient technique for the cooperative multi-cell DL system to deal with the space constraints and the aforementioned interferences. Furthermore, the considered preprocessing results in superior symbol-error-rate performance compared with other preprocessing approaches.

Performance of Cooperative Multi-Cell Downlink Communication Aided by Polarization-Multiplexing Under Limited Feedback Constraints

Next generation of 5G mobile communications heavily relies on exploiting the spatial degrees of freedom of the radio channels. For this reason, the idea of having base stations (BSs) with a large number of antennas is currently one of the main research topics in the wireless communications field.

Performance analysis of the Singular Value Decomposition with block-diagonalization precoding in Multi-User Massive MIMO systems

Studies on a massive Multiple-Input Multiple-Output (MIMO) system have been studied in recent years. In a massive MIMO system, antenna elements are arranged not in one dimension but in two dimensions because very large number of antenna elements are used, and the system is called a full-dimension MIMO. In this paper, we generate channel matrices between a transmitter at a base station and user equipments by using a ray tracing technique and evaluate the channel capacity with different places of a transmit antenna array in an indoor environment. In addition, we introduce block SNR maximization and compare the performance with that of block diagonalization. Sum capacity in the case when the BS is placed at the ceiling is larger than one in the case of placing at the wall.

Performance comparison of full-dimension MIMO systems with different base station places

In this paper, we consider the performance of leakage based linear precoding scheme in downlink multiuser MIMO. This work focuses on minimizing the interference to improve the performance system. The proposed leakage based linear precoding will be investigated in term of bit error rate (BER), sum rate capacity and outage. Simulation results show that the leakage based linear precoding scheme (MMSE SLNR and BD SLNR) achieved better BER, higher sum rate capacity, and lower outage than non-leakage precoding scheme (BD). At specific 10 dB SNR, there are 2.3 10 and 1.8 10 of target BER for MMSE SLNR and BD SLNR, respectively. Furthermore, the MMSE SLNR yields a lower outage than BD SLNR, at specific 2 dB SINR, the probability of an outage is 0.65 for MMSE SLNR and 0.86 for BD SLNR. Overall, the MMSE has better performance than BD SLNR because it has capabilities to eliminate the IUI and ISI. 

/pdf/performance-of-leakage-based-precoding-scheme-for-minimizing-5bynx54ofk.pdf

Performance of Leakage Based Precoding Scheme for Minimizing Interference

Large Scale Multiuser multiple input multiple output (LS-MU-MIMO) communication system is considered as an encouraging solution to attain greater spectral efficiency for the next-generation wireless communication system. In this paper, we propose an improved design of a precoding algorithm for LS-MU-MIMO communication system. The proposed precoding algorithm is based on Block diagonalization (BD) precoding which is a combination of QR decomposition and Zero forcing channel inversion (ZF-CI) operation named as QR-ZF-BD precoding algorithm. To enhance the performance of LS-MU-MIMO system, the proposed precoding algorithm utilizes ZF method and QR decomposition operation instead of more complex Singular value decomposition (SVD) operation as compared to the conventional Block diagonalization (BD) precoding technique. The proposed precoding algorithm is designed in two stages. In the first stage, the proposed QR-ZF-BD precoding algorithm first utilizes QR decomposition to diminish multiuser interference (MUI), the second stage utilizes ZF based channel inversion (ZFCI) and QR decomposition operation again to further enhance the spectral efficiency of a single cell downlink LSMU-MIMO system. The enhanced spectral efficiencies of values 334 bit/s/Hz and 388 bit/s/Hz are obtained with our proposed precoding algorithm design when LS-MU-MIMO system having 100 and 200 base station antennas respectively. The numerical results indicate that the proposed QR-ZF-BD precoding algorithm achieves the best spectral efficiency as compared to current LTE-A standard and other recently used conventional linear precoding algorithms.

/pdf/improved-precoding-algorithm-design-for-downlink-large-scale-zrlucl8hq4.pdf

Improved Precoding Algorithm Design for Downlink Large Scale MU-MIMO System

The block diagonalization (BD) is a linear precoding technique for multi-user multi-input multi-output (MIMO) broadcast channels, which is able to completely eliminate the multi-user interference (MUI), but it is not computationally efficient. In this paper, we propose the block diagonal Jacket matrix decomposition, which is able not only to extend the conventional block diagonal channel decomposition but also to achieve the MIMO broadcast channel capacity. We also prove that the QR algorithm achieves the same sum rate as that of the conventional BD scheme. The complexity analysis shows that our proposal is more efficient than the conventional BD method in terms of the number of the required computation.

/pdf/a-simple-block-diagonal-precoding-for-multi-user-mimo-3lbuihpqdt.pdf

A simple block diagonal precoding for multi-user MIMO broadcast channels

Multi-input multi-output (MIMO) precoding is developed for time division duplex (TDD) systems with block diagonalization (BD) relies on the channel state information (CSI) at the transmitter. Multi-cell BD algorithm is used to coordinate the transmissions across multiple evolved base stations (BSs) for downlink. In this paper, we apply BD to the downlink transmission in a cooperative multi-cell system, where the signals from different BSs to all the mobile stations (MSs) are jointly designed with the perfect knowledge of the downlink channels and transmit messages. The optimal form of BD with per-antenna power constraints and sum rate capacity are derived. Based on convex optimization techniques, this paper designs an efficient algorithm to solve this problem, and derives the structure of the corresponding optimal BD precoding matrix. The numerical results show that the proposed scheme is better performance than conventional scheme.

Multi-Cell block diagonalization precoding for multiuser MIMO broadcast channel

In this paper, we investigate the optimization problem of joint source and relay beamforming matrices for a two-way amplify-and-forward (AF) multi-input multi-output (MIMO) relay system. The system, consisting of two source nodes and two relay nodes, is considered, and the linear minimum mean-square-error (MMSE) is employed at both receivers. We assume individual relay power constraints and study an important design problem, a so-called determinant maximization (DM) problem. Since this DM problem is nonconvex, we consider an efficient iterative algorithm by using an MSE balancing result to obtain at least a locally optimal solution. The proposed algorithm is developed based on QL, QR, and Choleskey decompositions which differ in complexity and performance. Analytical and simulation results show that the proposed algorithm can significantly reduce computational complexity compared with their existing two-way relay systems and have equivalent bit-error-rate (BER) performance to the singular value decomposition (SVD) based on a regular block diagonal (RBD) scheme.

/pdf/low-complexity-ql-qr-decomposition-based-beamforming-design-1sunii4mcw.pdf

Low-complexity QL-QR decomposition- based beamforming design for two-way MIMO relay networks

In this letter, in order to reduce the inter-channel interference at the transmitted side, we design the precoder based on Tomlinson-Harashima coding, which is well know for one kind of non-linear precoding schemes, for 3-user MIMO wireless systems. And its performance is also analyzed in comparison with that of the Dirty Paper Coding based precoder.

3 User Non-Linear Tomlinson-Harashima Precoding

We present a DNA-RNA genetic code with their base complementarity, i.e., A = T (or U in RNA) = 30%, C = G = 20%, and C + U = G + A stemming from the fact that Erwin Chargaff discovered from his experimental results in 1950. These results strongly hinted that A and T are complementary base pairs, and C and G are also complementary base pairs, although he had no idea of them at that time. However, it has not been proved in a mathematically analytical point of view yet. In this paper, we have straightforward proof of this problem based on life ecosystem management by applying the doubly stochastic matrix to the Shannon entropy of the symmetric channel capacity.

Kye-Mun Cho

Papers

A simple block diagonal precoding for multi-user MIMO broadcast channels

Multi-Cell block diagonalization precoding for multiuser MIMO broadcast channel

Low-complexity QL-QR decomposition- based beamforming design for two-way MIMO relay networks

3 User Non-Linear Tomlinson-Harashima Precoding

A Life Ecosystem Management with DNA Base Complementarity