Jing Jin

China Mobile Research Institute, Peping, Beijing, China

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Publications (15)0.31 Total impact

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    ABSTRACT: Coordinated multi-point (CoMP) transmission is a promising technique to suppress inter-cell interference (ICI) in LTE-Advanced system. With perfect channel state information (CSI) at the transmitter, joint beamforming methods can be used to completely cancel ICI and significantly improve the spectrum efficiency. However, in FDD system, the transmitter can't obtain perfect CSI to eliminate ICI, for it's unreasonable to feed back the full channel information through the capacity limited feedback channel. In this paper, we propose a channel compression feedback scheme for FDD-CoMP system and adopt joint beamforming methods to partially mitigate ICI. In order to provide multi-cell spatial channel information and improve the feedback efficiency, the row and column number of the channel matrix are compressed using eigenmode of the user and codebook defined for LTE, respectively. Then, joint block diagonalization beamforming algorithm is applied at the transmitter to further eliminate ICI. Simulation results demonstrate that CoMP with the proposed feedback method can greatly improve the average and cell-edge spectral efficiency compared to the traditional cellular FDD system.
    GLOBECOM Workshops (GC Wkshps), 2010 IEEE; 01/2011
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    ABSTRACT: LTE-Advanced systems are built upon the orthogonal frequency division multiple access (OFDMA) technology, which can effectively eliminate the intra-cell interferences, but cannot automatically mitigate the inter-cell interferences (ICI). Coordinated multi-point transmission/reception (CoMP) is one of the candidate enhancement techniques for LTE-Advanced systems to increase both the average and the cell-edge user throughputs in uplink as well as downlink transmissions by jointly managing the inter-cell interferences. Although CoMP may incur more system complexity, it potentially could lead to significant capacity and coverage benefits, which makes it worth more detailed investigation. In this paper, we focus on downlink multi-point coordinated beamforming (CoMP-CBF), and study a particular multi-stream beamforming scheme. We also present detailed system level performance evaluation of the proposed scheme against a reference LTE Rel.8 non-cooperative scheme, which shows that CoMP-CBF transmission could achieve significant gains on both the average and the cell-edge user throughputs.
    Circuits, Systems and Computers, 1977. Conference Record. 1977 11th Asilomar Conference on 01/2011;
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    ABSTRACT: LTE-Advanced extends the number of transmit antennas of evolved NodeB (eNB) up to 8, which will provide substantial spatial degrees of freedom. However, the user is usually equipped with a small number of antennas due to space constraints. Thus, multi-user beamforming (MU-BF) was proposed to dramatically boost the spectrum efficiency by transmitting multiple users' data on the same time-frequency resource. The co-channel interference (CCI) among users scheduled on the same resource can be eliminated by block diagonalization (BD); however, the performance of downlink MU-BF with BD relies on the accuracy of channel estimation to a great extent. Therefore, the effect of imperfect channel estimation on MU-BF for the downlink of LTE-Advanced system is studied in this paper. The reference signal targeting data demodulation (DM-RS) and uplink sounding reference signal (SRS) for deriving the downlink channel in TDD system are considered with different error models respectively. The estimation errors are modeled through link level simulations. It is shown that the imperfect SRS and DM-RS channels degrade the system performance in different degree through system level simulation.
    Proceedings of the 71st IEEE Vehicular Technology Conference, VTC Spring 2010, 16-19 May 2010, Taipei, Taiwan; 01/2010
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    ABSTRACT: In LTE downlink multiple-input multiple-output (MIMO), eigen based beamforming (EBB) is a promising approach for single-user scenario, while block diagonalization based beamforming (BDBF) eliminates intra-cell interferences significantly for multi-user scenario. However, both of them neglect inter-cell interferences which may lead system performance degradation. This paper presents an interference suppression based beamforming (ISBF) scheme to suppress inter-cell interferences. We first introduce interference suppression matrix (ISM) into EBB and BDBF to propose a novel beamforming matrix construction method. Then the ISM reporting scheme is discussed to support ISBF, and a precoded uplink pilot based (PUPB) reporting scheme is presented exploiting the channel reciprocity in TDD system. Finally, the simulation results are provided using dynamic system level simulator. Our results show that ISBF improves cell average and cell edge spectral efficiency significantly compared with traditional EBB and BDBF.
    Proceedings of the 72nd IEEE Vehicular Technology Conference, VTC Fall 2010, 6-9 September 2010, Ottawa, Canada; 01/2010
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    ABSTRACT: For the shared frequency band between uplink and downlink, the channel reciprocity has been regarded as the most important advantage of a TDD system, in which the eNB can obtain the downlink channel state information (CSI) based on the uplink channel estimation, and thus perform advanced multi-antenna technologies to enhance the downlink transmission in TD-LTE/TD-LTE-Advanced systems. In this paper, the achievability of the TDD channel reciprocity from the product implementation point of view is analyzed and some measurement results of the hardware response difference before and after the antenna calibration have been shown to verify the achievability. Based on the channel reciprocity of TDD system, the performance of Single-User and Multiple-User Beamforming (SU/MU-BF) and Coordinated Multipoint Transmission (CoMP) have been enhanced significantly.
    01/2010;
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    ABSTRACT: LTE-Advanced system based on orthogonal frequency division multiplexing (OFDM) can eliminate intra-cell interference since data are carried on the orthogonal subcarriers; however, it can not mitigate inter-cell interference (ICI) which affects the performance severely. Therefore, coordinated multiple point (CoMP) reception scheme was proposed to reduce ICI and improve the cell capacity for the uplink of LTE-Advanced system. The basic idea of CoMP is to extend the conventional system to a multi-cell MIMO structure by sharing necessary information and received signals across multiple evolved Node Bs (eNB). This paper focus on evaluation of the CoMP scheme in which joint detection with minimum-mean-square-error (MMSE) algorithm is configured at the eNB side to cancel the ICI from other users. To guarantee fairness of the cell-edge users, proportional fair (PF) scheduling method is adopted. Simulation results for uplink show that the CoMP scheme can significantly improve the average cell throughput and reduce ICI for the cell-edge users.
    Communications, 2009. APCC 2009. 15th Asia-Pacific Conference on; 11/2009
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    ABSTRACT: To further improve and satisfy the spectral efficiency requirements addressed in LTE-Advanced system, in this paper, a Coordinated Multi-Cell MU-MIMO scheme is proposed to achieve this goal, especially to enhance the cell-edge user(the 5% of user throughput) throughput substantially. In our proposed cooperative scheme, we adopt multi-cell block diagonalization (BD) algorithm to perform joint procession across the evolved coordinated eNodeBs to mitigate the inter-cell interference (ICI) so as to enhance the whole system performance. Proportional fair (PF) scheduling algorithm is also applied to guarantee the fairness between the users. Furthermore, different numbers of antennas employed at the eNodeB are considered and their affects on our proposed cooperative scheme are analyzed as well. Of course, a system simulation platform is established for the downlink LTE-Advanced system to evaluate the performance of this scheme from the system level perspective. Ultimately, from the simulation results, we can draw that the coordinated multi-cell MU-MIMO scheme we proposed is an effective approach to improve the spectral efficiency prominently and much more spectral efficient comparing to conventional non-cooperative MIMO scheme for the downlink LTE-Advanced system.
    Personal, Indoor and Mobile Radio Communications, 2009 IEEE 20th International Symposium on; 10/2009
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    ABSTRACT: LTE-Advanced system which based on orthogonal frequency division multiplexing (OFDM) can eliminate intra-cell interference but still can not mitigate inter-cell interference (ICI). Coordinated Multi-Point transmission/reception (CoMP) is one of the candidate techniques for LTE-Advanced systems to increase the cell average and cell edge user throughput in the both uplink and downlink. Although CoMP naturally increases system complexity, it has potentially significant capacity and coverage benefits, making it worth a more detailed consideration. In this paper, we present our initial views on the application of BBU+RRU based CoMP system to LTE-Advanced. Furthermore, simulation results for uplink show that the CoMP joint processing can bring significant gains to both the average sector throughput and the 5% of user throughput.
    Communications Workshops, 2009. ICC Workshops 2009. IEEE International Conference on; 07/2009
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    ABSTRACT: LTE-advanced system which based on orthogonal frequency division multiplexing (OFDM) can eliminate intra-cell interference but still can not mitigate inter-cell interference (ICI). In this paper, we propose a novel cooperative multi-cell multiple-input multiple-output (MIMO) scheme for LTE-advanced system to reduce ICI and improve the cell capacity. By sharing information such as data and channel state information (CSI) across multiple evolved NodeBs (eNB) and configuring joint preceding at cooperative transmitters, the ICI may be mitigated or even beneficial. Multi-cell block diagonalization (BD) algorithm is used to coordinate the transmissions across multiple eNBs for downlink. To guarantee fairness of the cell-edge users, round robin (RR) scheduling is applied. Simulation results for downlink show that the proposed multi-cell MIMO scheme can significantly improve the average cell throughput and reduce ICI for the cell-edge users.
    Communications Workshops, 2009. ICC Workshops 2009. IEEE International Conference on; 07/2009
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    ABSTRACT: Fixed relay as a candidate solution in the cellular system attracts more and more attention due to its improvements of coverage and capacity. In this paper, we make our study on the optimal configurations of two-hop relay downlink system. Based on former works, two typical resource allocation schemes of the two hops are considered on the assumption of TDD system-one is in time domain and the other is in frequency domain. Based on the improved evaluation model, we demonstrate that it is critical to improve the capacity of the BS to RS link to achieve higher system throughput. Then, different RS positions are discussed in terms of the system throughput and the optimal deployment of Relay Station (RS) is concluded. In addition, we find that the ratio between the transmit power of base station (BS) and that of RS influences the throughput greatly.
    Proceedings of the 69th IEEE Vehicular Technology Conference, VTC Spring 2009, 26-29 April 2009, Hilton Diagonal Mar, Barcelona, Spain; 01/2009
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    ABSTRACT: In IEEE 802.16e mobile WiMAX system, since mobile stations (MSs) send bandwidth request (BR) messages to base station (BS) during contention period when they need uplink channel to transmit data in the case of multicast polling or broadcast polling, the uplink performance is affected by the size of the contention period in the uplink subframe. The access delay will be increased if the size of the contention period is too small and the resource will be wasted on the contrary. Therefore, we propose a cross-layer analytical model for designing the optimal size of the contention period. The model is simulated using OPNET modeler, and the results show that our proposed model can improve the uplink data transmission efficiency.
    Wireless Communications, Networking and Mobile Computing, 2008. WiCOM '08. 4th International Conference on; 01/2008
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    ABSTRACT: Mobile WiMAX as an OFDMA (Orthogonal Frequency Division Multiple Access) mobile broadband air interface is a solution to the requirements for mobile internet services. It has been accepted by ITU as 3G standard last year. The work presented in this paper focuses on evaluation of the Mobile WiMAX system performance in which Full-Queue and VoIP traffic are considered both in downlink and uplink We have proposed a virtual MIMO scheduling process in uplink We also discussed the system throughput of three frequency reuse schemes including reuse 1, reuse 3 and the FFR (Fractional Frequency Reuse). The former work is concentrated on the spectrum efficiency in [3-6], while this paper is a valuable replenishment to them.
    Proceedings of the 68th IEEE Vehicular Technology Conference, VTC Fall 2008, 21-24 September 2008, Calgary, Alberta, Canada; 01/2008
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    ABSTRACT: This letter proposes a new algorithm for the check node update in the decoding of low-density parity-check (LDPC) codes. The proposed algorithm is based on a new approximation formula of standard sum-product algorithm (SPA) which can reduce the approximation error of min-sum algorithm (MSA) and has almost the same performance as sum-product algorithm (SPA) under both floating precision operation and fixed-point operation. Besides, the new approximation formula can be implemented in simple structures competitive with MSA.
    IEICE Transactions on Communications 07/2007; · 0.31 Impact Factor
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    ABSTRACT: In this paper, we present two closed loop transmit diversity schemes for the systems which have designed closed loop power control scheme where the transmitter has equipped with two antennas and the receiver has one antenna. The proposed schemes do not require any additional feedback bits but utilize only the existing closed loop power control command bit in the system. The two proposed schemes are phase transmit diversity (PTD) and selection transmit diversity (STD), respectively. The simulation results show that, compared with single antenna system, the proposed schemes can reduce the transmit power considerably in different fading channels under low mobility conditions
    Wireless Communications, Networking and Mobile Computing, 2006. WiCOM 2006.International Conference on; 10/2006
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    ABSTRACT: Collaborative transmission among evolved Node-Bs (eNBs) is one of the promising techniques for LTE-Advanced to provide broader coverage and higher spectral efficiency. The interference among multi-cell transmission can be mitigated by joint precoding, such as multi-cell block diagonalization (BD) at cooperative eNBs. The major difference between multi-cell and single-cell transmission is that the power constraint has to be considered on a per-eNB basis. To satisfy per-eNB power constraint (PePC), a simplified power allocation algorithm for the multi-cell BD based collaborative transmission is proposed in this paper. The algorithm provides a power allocation coefficient matrix for BD to meet PePC. Simulation results demonstrate that the proposed algorithm has a near-optimal performance with simplicity.
    Frontiers of Electrical and Electronic Engineering in China 6(4).