Coordinated Multi-point Transmission And Reception Research Articles

Energy-Efficient Resources Allocation With Millimeter-Wave Massive MIMO in Ultra Dense HetNets by SWIPT and CoMP

Ultra-dense HetNets (UDN)-based Millimeter-Wave (mmWave) massive MIMO is considered a promising technology for 5th generation (5G) wireless communications systems since it can offer massively available bandwidth and improve energy efficiency (EE) substantially. However, in UDN, the power consumption of the system increases sharply with the increase of network density. In this paper, we investigate the optimization of the EE in the mmWave massive MIMO systems with UDN. To develop the functions of massive MIMO, we first propose a system model where the massive MIMO harvests electromagnetic energy from the environment employing simultaneous wireless information and power transfer (SWIPT) technology, implemented at the base station (BS). Then, the EE optimization problem is formulated for 5G mmWave massive MIMO systems within the UDN. Considering the nonconcave feature of the objective function, an iterative EE algorithm is developed, based on Dinkelbach method. To utilize the role of coordinated multi-point transmission and reception (CoMP) for improving the EE, a coordinated user(UE)-BS association algorithm-based CoMP with maximum energy efficiency (MaxEE) is proposed. The simulation results demonstrate that the proposed algorithm has a substantially faster convergence rate and is very effective, compared with existing methods.

Comparative Analysis of Intercell Interference Mitigation Techniques in LTE-A Network

The performance of long term evolution-advance (LTE-A) depends on different factors such as spectral efficiency, throughput and signal interference to noise ratio (SINR). Interference causes the performance of a network to be grassed to very low level, it directly affects the parameters such as noise interference, receiving diversity and system receiving gain so to mitigate the interference in LTE-A network is very important. Interference occurs in two forms, intra-cell interference and inter-cell interference. Intra-cell interference is removed by orthogonal frequency division multiple access, but the problem of inter-cell interference still exists due to reception of signals from two adjacent base stations at same frequency on user equipment, so coordination is applied between the cells to reduce the interference between the cells. This paper focuses on coordination between the base stations using dynamic cooperative Base Station selection (DCBS). In this paper, SINR, system capacity, minimum and maximum rates of the system are analyzed when coordination is applied between the cells. Three different scenarios are discussed in this paper, which includes coordinated multipoint transmission and reception (COMP), non-COMP and DCBS and then the results of these scenarios are compared.

A Novel Network Architecture for C/U-Plane Staggered Handover in 5G Decoupled Heterogeneous Railway Wireless Systems

Previously, we proposed a broadband fifth-generation (5G) control/user (C/U)-plane decoupled heterogeneous railway wireless system to meet the exponentially increasing capacity demands in railway. Nevertheless, service interruptions due to the handovers in overlapping registration areas are still challenging in railway wireless systems. How to achieve soft and fast handovers to overcome these challenges attracts intensive attention finally. In this paper, we propose a novel network architecture for 5G C/U-plane decoupled heterogeneous railway wireless systems to physically separate and stagger the C-plane and U-plane handovers. During the C-plane handover process that occurs between the macro-cells, the U-plane is always kept connected without any handover, which achieves non-interruptible soft handover. Moreover, since there are no handovers in the U-plane, the handover procedure is significantly simplified, thereby accelerating the handover process. Similarly, during the U-plane handover process, which happens between the small cells, the C-plane is kept connected all the time, saving the otherwise intensive C-plane handover signaling. Besides, the coordinated multi-point transmission and reception (CoMP) and bi-casting technologies are applied to establish the target U-plane connection ahead of cutting off the old one, so that no interruption occurs during the U-plane handover process. This paper demonstrates that the proposed handover schemes can greatly improve the handover performance.

Linear transceiver design in uplink coordinated multipoint multiple‐input multiple‐output systems

The authors investigate linear transceiver design in uplink (UL) coordinated multipoint transmission and reception (CoMP) multiple-input multiple-output (MIMO) systems with joint detections. A two-stage design algorithm is proposed by exploiting the technique of interference alignment, optimising the structure of the effective channel and employing power loading, with the goal to achieve high throughput and convergence performance. In contrast to conventional CoMP transceiver design, which is investigated under a predefined number of data streams transmitted by each user, the authors further investigate the selection of the number of data streams, called the configuration selection, and propose a corresponding low-complexity algorithm. By combining the proposed linear transceiver algorithm and low-complexity configuration selection algorithm, this work presents a new practical framework for linear transceiver design in UL CoMP MIMO systems. The simulation results confirm that the proposed algorithms achieve higher sum-rate performance than prior linear transceivers used in UL CoMP MIMO systems. Furthermore, the proposed transceiver offers comparable performance to existing IA-aided transceivers with significantly faster convergence.

Design and Performance Enhancements in Communication-Based Train Control Systems With Coordinated Multipoint Transmission and Reception

A communication-based train control (CBTC) system is an automated train control system that uses bidirectional train–ground communications to ensure the safe operation of rail vehicles. CBTC systems have stringent requirements for communication availability and latency. Due to unreliable wireless communications and frequent handoffs, existing CBTC systems can severely affect train control performance, train operation efficiency, and the utility of railways. In this paper, we use recent advances in coordinated multipoint transmission and reception (CoMP) to enhance the train control performance of CBTC systems. With CoMP, a train can communicate with a cluster of base stations (BSs) simultaneously, which is different from the current CBTC systems, where a train can only communicate with a single BS at any given time. In addition, unlike the existing works on CoMP, in this paper, the linear quadratic cost for the train control performance in CBTC systems is considered the performance measure. We jointly consider the BS cluster selection and handoff decision issues in CBTC systems. Moreover, in order to mitigate the impacts of communication latency on train control performance, we propose an optimal guidance trajectory calculation scheme in the train control procedure that takes full consideration of the tracking error caused by handoff latency. Simulation results show that train control performance can be substantially improved in our proposed CBTC system with CoMP.

셀 경계 단말의 성능 향상을 위한 회전성 빔 방향 패턴의 활용

셀룰러 이동통신 시스템의 용량과 커버리지를 향상시키기 위한 많은 연구 결과들이 시스템에 적용되었지만, 셀 경계에서의 심각한 성능 열화는 여전히 단말 전송률의 더 나은 향상을 가로막는 주요한 요인으로 남아있다. 3GPP (Third Generation Partnership Project)의 LTE-A (Long Term Evolution-Advanced) 표준에서는 협력적 전송 (CoMP, coordinated-multipoint transmission reception)과 ICIC (inter-cell interference coordination)와 같은 진보된 기술들이 셀 경계 성능 열화 문제를 해결하기 위해 소개되었다. 본 논문에서는 다수개의 빔 방향 패턴 (BDP, beam direction pattern)을 활용하여 셀 경계 단말들의 성능을 향상시킬 수 있는 방안을 제안한다. 다수개의 빔 방향 패턴은 기지국에 설치된 복수 계층 안테나 어레이를 사용해 구현될 수 있다. 고정된 빔 패턴을 갖는 기존의 3섹터 안테나와 비교해서, 제안하는 방식은 다수개의 BDP들이 시간상에서 회전하면서 신호를 전송하게 된다. 이를 통해 셀 또는 섹터 경계에 위치하는 특정 단말들이 기지국으로부터 전체 전송 시간에 걸쳐 나쁜 성능의 신호를 수신하게 되는 상황을 억제함으로써, 해당 단말들의 수신 신호 품질을 향상시킬 수 있다. 성능 평가 결과는 제안하는 방식이 기존 3섹터 전송 방식에 비해 평균 단말 전송률 측면에서 하위 5% 단말에서 약 171% 향상된 성능을 나타냄을 보여준다.

Performance Evaluation of Coordinated Multi-Point Transmission and Reception in Indoor Mobile Communication Systems

Recently, mobile communication systems are suffering from exponentially increasing data traffic. As a promising solution to the increase in data traffic, a coordinated multi-point transmission and reception (CoMP) scheme has been proposed. Although a great deal of research has been done on this new technology, the performance of mobile communication systems with CoMP has not been evaluated properly in a typical indoor environment. To address this, we have developed a system-level simulator and evaluated the performance of mobile communication systems with CoMP. Unlike previous works, we have used an actual antenna pattern in our simulator and link-level results are properly taken into account through link-level abstraction. By using a system-level simulator, we have evaluated the performance of mobile communication systems with CoMP in an indoor environment and found that unlike an outdoor cellular environment, CoMP may not improve the performance of overall mobile communication systems in an indoor environment.

Quantitative analysis of split base station processing and determination of advantageous architectures for LTE

Centralization of the baseband processing in radio access networks may reduce radio site operations costs, reduce capital costs, and ease implementation of multi-site coordination mechanisms such as coordinated multipoint transmission and reception (CoMP). However, the initial architecture proposals for a centralized Long Term Evolution (LTE) deployment using transport of radio samples require a high-bandwidth, low-latency interconnection network. This may be uneconomical, or it may only be cost effective for a limited number of sites. To mitigate that deficiency without sacrificing the benefits of centralized processing, we identified alternative interfacing options between central and remote units. To do so we analyzed possible splits of the Long Term Evolution (LTE) baseband processing chain for their bandwidth and latency requirements. Next, we analyzed the operational impacts of potential splits based on a number of criteria including ease of CoMP introduction, the possibility of realizing pooling gains, and the ability to update the system and introduce new features. Based on our results, we propose architectures that can leverage the benefits of centralization at a much-reduced cost.

Optimal Power Allocation Scheme for Downlink CoMP Systems

Coordinated multi-point transmission and reception (CoMP) scheme enable LTE-Advanced systems to achieve their higher spectral efficiency. Allowing base stations to cooperate one another is one of the solutions to mitigate the inter-cell interference (ICI). In this paper, we propose an iterative power allocation scheme with MMSE procoding based on a modified water-filling for downlink CoMP systems, which achieves the optimal performance. The simulation results show that our proposed system can achieve its optimal rate according to its antenna configuration. Comparing them with a block diagonalization (BD) shows the advantages of MMSE precoding, in particular at a low SNR region.

제한적 궤환량 사용 시 부분적 CoMP 전송의 성능 이득

CoMP(Coordinated Multi-Point transmission and reception) refers to a cooperative transmission strategy to control the interference from adjacent base stations in cellular mobile communication systems, which efficiently enhances the data throughput of the systems. As the number of the base stations participating in cooperative transmission increases, however, a larger amount of information exchange to carry the CSI(Channel State Information) of the mobile terminals is required. In this paper, we propose a partial CoMP transmission method for systems under the constraint of finite feedback information data. This method selects candidates of base stations which can provide high efficiency gain when they participate in the CoMP set. To achieve this, the cooperative base station combination is constructed by considering the preferred base stations of users. The cooperative base station combinations are dynamically applied since the preferred base station combinations of users may be different. We perform computer simulations to compare performance of the non-CoMP, full-CoMP and partial CoMP in terms of the average throughput using finite feedback and demonstrate the performance improvement of the proposed method.

원격송신국을 활용하는 이종 네트워크 시스템의 성능 개선 방안

In this paper, we propose a method to improve cell edge users` performance in HetNet (heterogeneous network) systems by cooperatively transmitting signals using remote radio heads (RRHs) located near coverage boundaries, referred to as edge RRHs. The proposed method locates the edge RRHs in specific locations of the cell boundary and provides an efficient operational strategy by adjusting the duty cycle of the edge RRHs and base stations. The effectiveness of the method is demonstrated by experimental performance based on the system model parameters of the CoMP (coordinated multi-point transmission and reception) scenario, which is discussed in LTE-Advanced (Long Term Evolution - Advanced) standard contributions. When compared with conventional methods, utilization of edge RRHs is especially advantageous for the performance improvement of lower percentile users in terms of average throughput and effectively improves the fairness among users.

Improved resource allocation strategy in SU-CoMP network

Coordinated multi-point transmission and reception (CoMP) for single user, named as SU-CoMP, is considered as an efficient approach to mitigate inter-cell interference in orthogonal frequency division multiple access (OFDMA) systems. Two prevalent approaches in SU-CoMP are coordinated scheduling (CS) and joint processing (JP). Although JP in SU-CoMP has been proved to achieve a great link performance improvement for the cell-edge user, efficient resource allocation (RA) on the system level is quite needed. However, so far limited work has been done considering JP, and most existing schemes achieved the improvement of cell-edge performance at cost of the cell-average performance degradation compared to the single cell RA. In this paper, a two-phase strategy is proposed for SU-CoMP networks. CS and JP are combined to improve both cell-edge and cell-average performance. Compared to the single cell RA, simulation results demonstrate that, the proposed strategy leads to both higher cell-average and cell-edge throughput.