Jianchi Zhu

QoS-Guaranteed Radio Resource Allocation with Distributed Inter-Cell Interference Coordination for Multi-Cell OFDMA Systems

This paper proposes a novel distributed QoS-guaranteed multi-cell radio resource allocation (RRA) scheme for OFDMA systems, which includes two separate steps operated on two time levels: the Hungarian algorithm based intra-cell fast scheduling on the frame level and the X2 interface based inter-cell interference coordination (ICIC) algorithm performed on the super-frame level. The scheme is distributed in the sense that both algorithms are carried out by the enhanced Node B (eNB). Through intense analysis, we proved that the ICIC algorithm not only provides fine robustness against ICI but also achieves good load balancing from a new perspective. Simulation results indicate that the performance of the proposed scheme, when compared to the standard universal reuse approach without inter-cell coordination, is significantly better in terms of increasing both the network and cell-edge throughputs.

A Hybrid Inter-cell Interference Mitigation Scheme for OFDMA based E-UTRA Downlink

For the evolved UTRA (EUTRA), cell edge bit-rate and system throughput become important criteria for the evaluation of the system proposals and requirements on the system performance. Inter-cell interference is the main source of performance degradation for OFDM, especially the data rate of cell edge UEs is severely limited. Many inter-cell interference mitigation schemes are proposed to improve the EUTRA performance, especially the active coordination in the frequency domain resource allocation between neighboring cells. But they cant achieve robust performance for system throughput and cell edge bit rate when the traffic load varies much. In this paper a hybrid inter-cell interference mitigation scheme (HICIM) is proposed, which is a trade-off between system throughput and cell-edge UE performance. From the simulation results when proportional fairness (PF) scheduling is adopted in single input and single output (SISO) environment, the proposed HICIM scheme achieves robust performance of both system throughput and cell-edge UE performance for both high system load and low system load

Initial Performance Evaluation on TD-SCDMA Long Term Evolution System

As the evolution of 3G, long term evolution (LTE) standardization activity is issued in 3GPP and 3GPP2. In previous paper OFDMA is proposed for downlink of LTE. As the channel reciprocity can be obtained in TD-SCDMA LTE system, the channel status information (CSI) can be exploited at the transmitter to obtain the spatial-frequency multiuser diversity by joint spatial-frequency subcarrier and antenna assignment of MIMO OFDMA for the independent fading of different user in spatial and frequency domain. To guarantee the user fairness, a joint spatial-frequency proportional fairness (PF) scheduling is proposed in this paper. Further, no inter-cell interference mitigation capability can be observed from the current MIMO OFDMA schemes in downlink, the soft frequency reuse is adopted in this paper to avoid the inter-cell interference. Finally the downlink performance of the TD-SCDMA LTE with no-real time service is evaluated with spatial frequency PF scheduling and soft frequency reuse in multi-cell scenario

Channel and Queue Aware Scheduling for Mixed Service in Multiuser MIMO OFDM System

In MIMO OFDMA system, multiuser diversity gain can be achieved both in spatial and frequency domain by channel aware scheduling. For real time (RT) service, the data rate and the packet delay should be guaranteed. But for none-real time (NRT) service, larger packet delay is acceptable and multiuser diversity gain can be exploited more to improve the system throughput. In this paper, by exploiting the queue status information and channel status information, a novel framework of unified scheduling for mixed RT and NRT services is proposed for MIMO OFDMA system, and two novel joint spatial-frequency scheduler based on Modified Proportional Fairness (MPF) and Quality Guaranteed (QG) priority function are proposed. From the simulation results, QG&MPF has much better performance than M2PF. For 2times4 MIMO case, QG&MPF can support 40 RT user and 40 NRT users in 10 MHz bandwidth simultaneously, and the system throughput of QG&MPF can approach 32 Mbps; while M2PF can only support 15 RT users and 15 NRT users, and the system throughput is about 11.5 Mbps.

A Novel Scheme for OFDMA Based E-UTRA Uplink

For the Evolved UTRA (EUTRA), in OFDMA uplink, the Inter-cell interference cannot be predicted precisely, so scheduling becomes a puzzling problem and directly affects the uplink performance in OFDMA based system. Previous works (Galdata, et. al., 2003) did not concern such a problem or just consider single cell environment. In this paper, a novel scheme is proposed that could efficiently solve this problem in multi-cell circumstance. It predefines UEs distributed in the whole cell adopt fixed modulation and coding scheme (MCS) according to the distance from Node B. It employs initial average predictive interference to create the first-loop Inter-cell interference and perform scheduling according to the historical information in the following. Fast power control is adopted in order to compensate the imprecisely predictive inter-cell interference. Soft frequency reuse scheme is adopt in order to improve the cell-edge UE performance. To guarantee the UE fairness, proportional fairness (PF) scheduling is adopted in single input and single output (SISO) environment in this paper.

Enhanced Downlink Performance of TD-SCDMA LTE System with Multiuser MIMO SDM

Since the channel reciprocity can be obtained in TD-SCDMA LTE system, the channel status information (CSI) can be exploited at the transmitter to implement multiuser spatial division multiplexing (SDM) and obtain both the spatial multiplexing gain and multiuser diversity gain efficiently. In this paper, zero forcing beamforming (ZFB) and multiuser per antenna rate control with antenna selection (MU-PARC-AS) based SDM is proposed to enhance the downlink performance of TD-SCDMA LTE, and a joint spatial frequency proportional fairness (PF) scheduling is proposed to achieve the tradeoff between the user fairness and the system throughput of none-real time (NRT) service. For 10 MHz bandwidth, the system throughput of ZFB approaches 18 Mbps and 27 Mbps for 1times2 and 2times4 MIMO scenarios respectively, and the spectrum efficiency is achieved as 1.8 bps/Hz and 2.7 bps/Hz respectively. The cell throughput of ZFB is 38% and 17% higher than that of MU-PARC-AS for 1times2 and 2times4 MIMO scenarios respectively

Joint Space-Frequency-Power Scheduling Algorithm for Real Time Service in Cellular MIMO-OFDM System

To meet the increasing demand of wireless services associated with the scarcity of the radio spectrum and the trend to provide end to end quality of service (QoS), on the one hand advanced technologies that harness the available resource efficiently should be developed, on the other hand the collaboration of different layers such as physical (PHY) layer and medium access control (MAC) layer is needed. In this paper, we propose a joint space-frequency-power scheduling algorithm (JSFP) for real time service in multiuser cellular MIMO-OFDM system which jointly optimizes the subcarrier, bit and power allocation in the PHY layer along with the scheduling in the MAC layer to exploit the multiuser diversity. This algorithm considers both the user equipments (UE) QoS requirements (such as packet delay and packet loss ratio) and the UEs channel conditions and includes three parts: packet scheduling, subcarrier allocation and antenna selection, power allocation. Numerical results show that the proposed algorithm achieves significant system performance improvement compared with the conventional methods.

Channel and queue aware scheduling for real- time service in multiuser MIMO OFDM system

For real time service, not only the data rate, but also the packet delay should be guaranteed. In this paper, by exploiting the queue status information and channel status information, a novel framework of joint spatial-frequency scheduling for real time service in MIMO-OFDMA system is proposed, and some joint spatial-frequency scheduling algorithm is proposed based on modified largest weighted delay first (M-LWDF), quality guaranteed (QG) and packet loss ratio (PLR) priority function. Comparing the simulation results of MIMO 1times2 case, M-LWDF achieves best performance; QG and M-LWDF scheduler may support 20 video user with 500 kbps data rate in 10 MHz bandwidth, and the spectrum efficiency may approach 0.9 bps/Hz. while for MIMO 2times4 results, QG scheduler may achieve best performance comprehensively, and more than 50 video user can be supported in 10 MHz, and the spectrum efficiency may approach 2.5 bps/Hz.

System Performance Evaluation on FuTURE B3G TDD System from Field Channel Measurement

FuTUKE B3G TDD is designed to provide 100 Mbps peak data rate in both uplink and downlink. In this paper, based on the results from the field channel measurement, the radio transmission parameters of physical layer is optimized, and the downlink performance of FuTURE B3G TDD is evaluated in system level. To provide a multi-cell coverage, a soft frequency reuse is adopt. Further, a joint spatial and frequency scheduling is proposed to explore the multiuser diversity gain at both spatial and frequency domain. As the channel reciprocity can be obtained in TDD system, the Channel Status Information (CSI) can be exploited at the transmitter to obtain the spatial-frequency multiuser diversity by joint spatial-frequency subcarrier and antenna assignment of MIMO OFDMA for the independent fading of different user in spatial and frequency domain. With the optimised radio transmission parameters, the peak data rate and system throughput can be improved 12.7%. The downlink system throughput in multi-cell scenario can achieve about 30 Mbps with 4times2 MIMO in 10 MHz bandwidth.