Hoondong Noh

A practical MMSE-ML detector for a MIMO SC-FDMA system

We propose a new minimum mean square error (MMSE) based maximum likelihood (ML) detector for a single carrier frequency division multiple access system. By utilizing the distance between decision line and MMSE soft-output, the proposed detector reduces the resources required to check superfluously accurate reliability of received symbol. The proposed detector provides almost same bit error rate with the conventional MMSE-ML detector while requiring significantly low computational complexity (below 10%) as SNR varies.

Codebook Design of Generalized Space Shift Keying for FDD Massive MIMO Systems in Spatially Correlated Channels

The massive multiple-input multiple-output (MIMO) system is one of the most promising techniques for beyond fourth-generation (B4G) wireless communication systems. However, supporting a downlink (DL) frequency-division duplex (FDD) massive MIMO system for backward compatibility might be a bottleneck problem because the number of feedback bits for the FDD system is proportionate to the number of transmit antennas. In this perspective, the well-known generalized space-shift keying (GSSK) can be a suitable candidate to support the DL FDD massive MIMO system. In this paper, the GSSK activating all transmit antennas at once is named as port modulation (PM). PM has enormous potential to utilize the spatial resources of the massive MIMO system by linking precoding and the well-known spatial modulation (SM). In this paper, we propose a codebook design for PM, which makes it possible to improve the average bit error probability (ABEP) of PM without instantaneous channel state information (CSI) at the transmitter (CSIT) or additional efforts to design shaping filters. Simulation results show that when the base station consists of a large number of spatially correlated transmit antennas, the proposed codebook design offers lower ABEP than other limited feedback or open-loop systems, such as spacen-time-block-coded SM (STBC-SM).

A Covariance Approximation Method for Near-Field Coherent Sources Localization Using Uniform Linear Array

The covariance approximation (CA) multiple signal classification (MUSIC) is a novel near-field direction-of-arrival (DoA) estimation method for uniform linear array. In this paper, we show that the CA-MUSIC suffers from significant performance degeneration caused by coherent sources. The CA-MUSIC with coherent sources generates the image sources (IS), which cannot be distinguished from the real sources. To solve this problem, we propose a CA-based near-field coherent sources localization algorithm, which is robust to the IS effect. The proposed CA algorithm avoids errors caused by coherence between sources using searching radius restriction and zero-forcing MUSIC. Simulation results shows that the proposed CA algorithm offers superior root mean square error (RMSE) performances for near-field coherent sources.

An iterative MMSE-ML detector for MIMO SC-FDMA system

This paper proposes a new iterative minimum mean square error(MMSE) based maximum likelihood(ML) detector for a single carrier frequency division multiple access(SC-FDMA) system. In this scheme, conventional non-iterative ML post-detection process(ML-PDP) is modified to have an iterative structure. Modified iterative ML-PDP with reliability check enhances the system bit error rate(BER) performance about 1∼2dB per iteration at the BER of 10−. Additionally computational complexity caused by each iteration can be suppressed efficiently by adopting radius update process.

Modular and High-Resolution Channel State Information and Beam Management for 5G New Radio

This article provides an overview of key features pertaining to CSI reporting and beam management for the 5G New Radio (NR) currently being standardized in 3GPP. For CSI reporting, the modular design framework and high-resolution spatial information feedback offer not only flexibility in a host of use cases and deployment scenarios, but also improved average user throughput over state-of-the-art 4G LTE. To accommodate cellular communications in the milimeter-wave regime where a combination of analog and digital beamforming is typically used at both a base station and user equipment, beam management procedures such as measurement, reporting, and recovery are introduced. The utility and joint usage of these two features are demonstrated along with some potential upgrades for the next phase of 5G NR. Introduction

A Differential Trellis-Coded Quantization for FDD Massive MIMO Systems in a Spatially Correlated Channel

To obtain the beamforming gain of a frequency-division duplex massive multiple-input multiple-output system, extensive channel state information (CSI) should be accurately quantized and fed back to the base station. Trellis-coded quantization (TCQ) can reduce codebook size and codebook-searching complexity that are the main drawbacks of vector-quantization-based CSI feedback schemes. However, the beamforming gain of the conventional TCQ cannot be fully obtained in a spatially correlated channel that is inevitably involved in massive transmit arrays. In this letter, we propose a differential TCQ that exploits the channel correlation by using a compressive constellation and phase difference quantization. We present an algorithm for generating a phase difference constellation and a decoding process for the proposed differential TCQ. The proposed scheme can reduce the overhead of the codebook size problem by trellis decoding and improve the quantization performance at the same feedback rate compared to the conventional TCQ scheme.

3D beamforming for capacity boosting in LTE-advanced system

LTE-Advanced system has been deployed with 2 and 4 transmission antennas (Tx) while the specification supports up to 8Tx. Due to deployment space, antenna dimension and complexity, operators have not been interested in the deployment of 8Tx systems. Recently, three dimensional (3D) beamforming using 2D active antenna array has attracted significant attention in the wireless industry. By incorporating 2D active array into LTE-A systems, the system offers freedom in controlling radiation on elevation and horizontal dimension. In addition, 2D array antenna increases the number of antennas without exceeding form-factor where the conventional antennas are deployed. When the number of antennas increases in the form of 2D arrangement, spatial separation can be realized simultaneously in horizontal and elevation domain and vertical beam-steering can increase SINR of UEs in high floors. In this paper, we study the system operations and implementations for supporting 3D beamforming with 8Tx antennas. In our schemes, by reusing the conventional CSI feedback framework, the system can operate 2D active array without harming the backward compatibility. Evaluation results show that 3D beamforming provides capacity boosting over the conventional 2D beamforming systems while keeping same antenna structure.

A Spatial Modulation With Space-Phase Constellation for Spatially Correlated Channels

We design a spatial modulation (SM) scheme for spatially correlated channels under the constraints of a single radio frequency chain transmitter and open-loop transmission. To alleviate the performance degradation of the conventional SM in highly correlated channels, the proposed SM scheme adopts the antenna grouping and a new space-phase constellation, which is designed by considering the phase-only constraint and received symbol distance in fully correlated channels. In the simulation results, the proposed scheme achieves about 2.5-dB gain at bit error rate of

Channel Magnifying Limited Feedback Technique for FDD Massive MIMO Systems

10^{-3}

METHOD AND APPARATUS FOR SELECTING DEDICATED CORE NETWORK

compared with the conventional SM in highly correlated channels.