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Gerhard P. Fettweis - One of the best experts on this subject based on the ideXlab platform.

  • Uplink CoMP under a constrained backhaul and imperfect channel knowledge
    IEEE Transactions on Wireless Communications, 2011
    Co-Authors: Patrick Marsch, Gerhard P. Fettweis
    Abstract:

    Coordinated Multi-Point (CoMP) is known to be a key technology for next generation mobile communications systems, as it allows to overcome the burden of inter-cell interference. Especially in the uplink, it is likely that interference exploitation schemes will be used in the near future, as they can be used with legacy terminals and be based on operator-proprietary signal processing concepts, hence requiring no or little changes in standardization. Major drawbacks, however, are the extent of additional backhaul infrastructure needed, and the sensitivity to imperfect channel knowledge. This paper jointly addresses both issues in a new framework incorporating a multitude of proposed theoretical uplink CoMP concepts, which are then put into perspective with practical CoMP algorithms. This comprehensive analysis provides new insight into the potential value of different uplink CoMP concepts in next generation wireless communications systems, and reveals the subset of schemes that are most likely to be used in practice.

  • Large scale field trial results on different uplink Coordinated Multi-Point (CoMP) concepts in an urban environment
    2011 IEEE Wireless Communications and Networking Conference WCNC 2011, 2011
    Co-Authors: Michael Grieger, Gerhard P. Fettweis
    Abstract:

    Coordinated Multi-Point (CoMP) concepts such as multi-cell joint detection and transmission, promising large improvements in spectral efficiency and fairness, appears to be an effective option to combat inter-cell interference in mobile communications. One major drawback of uplink joint detection is the large additional backhaul required when compared to a non-cooperative system. Theoretical work has demonstrated how distributed interference subtraction can be used as a low backhaul option providing moderate CoMP gain. While a large amount of theoretical work has been carried out on this topic, and previous publications have shown that these schemes work in principle, the scenarios of urban deployment and the extent of capacity gains that can be achieved are still unclear. To this end, we compare potential rate gains through linear and non-linear uplink CoMP schemes for a large scale field trial setup wherein two mobile terminals have been moved through an urban test bed of 12 base stations located at UMTS sites in downtown Dresden.

  • Large scale field trial results on uplink CoMP with multi antenna base stations
    IEEE Vehicular Technology Conference, 2011
    Co-Authors: Michael Grieger, Gerhard P. Fettweis
    Abstract:

    Coordinated Multi-Point (CoMP) appears to be an effective option to combat inter-cell interference in mobile communications. Previous field trials for uplink CoMP have shown that large improvements in spectral efficiency and fairness that are promised by theoretical work can also be achieved in real-world scenarios. However, these results only consider systems with single antenna base stations. We extend this work by presenting field trial results for a system with multi antenna base stations, and we show that this change of the system setup has a strong impact not only on the throughput but also on the relative performance of a cooperative compared to a non-cooperative system. Based on the presented results suggestions for further research and field trials are derived.

  • uplink comp under a constrained backhaul and imperfect channel knowledge
    arXiv: Information Theory, 2010
    Co-Authors: Patrick Marsch, Gerhard P. Fettweis
    Abstract:

    Coordinated Multi-Point (CoMP) is known to be a key technology for next generation mobile communications systems, as it allows to overcome the burden of inter-cell interference. Especially in the uplink, it is likely that interference exploitation schemes will be used in the near future, as they can be used with legacy terminals and require no or little changes in standardization. Major drawbacks, however, are the extent of additional backhaul infrastructure needed, and the sensitivity to imperfect channel knowledge. This paper jointly addresses both issues in a new framework incorporating a multitude of proposed theoretical uplink CoMP concepts, which are then put into perspective with practical CoMP algorithms. This comprehensive analysis provides new insight into the potential usage of uplink CoMP in next generation wireless communications systems.

  • Bit per joule efficiency of cooperating base stations in cellular networks
    2010 IEEE Globecom Workshops GC'10, 2010
    Co-Authors: Albrecht J. Fehske, Gerhard P. Fettweis
    Abstract:

    Energy consumption is lately receiving increased interest, and research efforts to assess the energy efficiency of cellular communication networks are made. This paper addresses the tradeoffs between gains in cell throughput that can be expected from Coordinated multi point transmission and reception technologies and the increased energy consumption that they induce in cellular base stations. We explicitly consider effective transmission rates, taking into account the additional pilot, control and feedback overhead required for CoMP schemes, and determine the bit per Joule efficiency of network models for common propagation parameters under varying network densities and cooperation cluster sizes.

Ming Lei - One of the best experts on this subject based on the ideXlab platform.

  • Retrieving Channel Reciprocity for Coordinated Multi-Point Transmission with Joint Processing
    IEEE Transactions on Communications, 2014
    Co-Authors: Gang Wang, Ming Lei
    Abstract:

    In time division duplex Coordinated Multi-Point transmission with joint processing (CoMP-JP) systems, the uplink-downlink channels are no longer reciprocal. Due to the difficulty of antenna calibration among the Coordinated base stations (BSs), practical downlink channels differ from uplink channels by multiplicative ambiguity factors, which lead to severe performance degradation. In this paper, we propose an inter-BS antenna calibration strategy to facilitate downlink CoMP-JP transmission, whose basic idea is to estimate the ambiguity factors. To establish the observation equations for estimation, an extra uplink training frame except for the regular uplink and downlink frames is introduced, and existing signalling framework of limited feedback can also be reused. To improve the estimation performance, we can either select multiple users or employ multiple frames of one user to assist the calibration. After establishing the observation equations respectively with uplink training or limited feedback, the weighted least square criterion is used for estimation. We proceed to analyze and compare the mean square errors of the estimators, and provide a principle to select the users for assisting calibration. Simulation results show that the channel reciprocity is largely retrieved by the proposed antenna calibration strategy, which provides substantial throughput gain over the CoMP-JP systems without inter-BS calibration.

  • Coordinated multi point transmission strategies for tdd systems with non ideal channel reciprocity
    IEEE Transactions on Communications, 2013
    Co-Authors: Shengqian Han, Gang Wang, Dalin Zhu, Ming Lei
    Abstract:

    This paper studies transmission strategies for downlink time division duplex Coordinated Multi-Point (CoMP) systems with non-ideal uplink-downlink channel reciprocity, where several multi-antenna base stations (BSs) jointly serve multiple single-antenna users. Due to the inherent antenna calibration errors among different BSs, the uplink-downlink channels are no longer reciprocal such that the channel information at the BSs is with multiplicative noises. To mitigate the performance degradation caused by the imperfect channels, we employ a weighted sum rate estimate as the objective function for robust precoder design. To show the impact of data sharing on the performance of CoMP under the non-ideal channel reciprocity, we provide a unified framework for designing precoder for CoMP systems with different amount of data sharing. The optimal parametric linear precoder structure that maximizes the weighted sum rate estimate under per-BS power constraints is characterized, based on which a closed-form robust signal-to-leakage-plus-noise ratio (SLNR) precoder is proposed to exploit the statistics of the calibration errors. Simulation results show that the proposed precoder in conjunction with user scheduling provides substantial performance gain over Non-CoMP transmission and the CoMP transmission with non-robust precoders.

  • retrieving channel reciprocity for Coordinated multi point transmission
    Wireless Communications and Networking Conference, 2013
    Co-Authors: Gang Wang, Ming Lei
    Abstract:

    Due to the difficulty of self antenna calibration among different base stations (BSs), the uplink-downlink channels are no longer reciprocal in time division duplex Coordinated Multi-Point transmission with joint processing (CoMP-JP) systems. To retrieve the channel reciprocity, we propose an inter-BS antenna calibration method. Specifically, we estimate the inter-BS ambiguity factors with weighted least square criterion by using the uplink and downlink channel estimates and the received signal of a calibration sounding signal of multiple supporting users or multiple frames. We then analyze the mean square error of the proposed estimator, and compare the performance of the estimators with multiple supporters and with multiple frames. Simulation results show that the channel reciprocity is largely retrieved by the proposed antenna calibration method, which provides substantial throughput gain over the CoMP-JP systems without calibration.

  • Coordinated multi point transmission with non ideal channel reciprocity
    Wireless Communications and Networking Conference, 2012
    Co-Authors: Shengqian Han, Gang Wang, Dalin Zhu, Ming Lei
    Abstract:

    This paper studies robust transmission strategies for downlink time division duplex Coordinated Multi-Point (CoMP) systems with non-ideal uplink-downlink channel reciprocity due to imperfect antenna calibration. By exploiting the statistics of antenna calibration errors, we first characterize the optimal parametric precoder structure that maximizes the weighted sum rate, based on which a closed-form robust signal-to-leakage-plus-noise ratio (RSLNR) precoder with properly selected parameters is then proposed. Simulation results show that the proposed precoder together with user scheduling provides near-optimal performance and data sharing among Coordinated BSs may become detrimental depending on the employed precoders and the accuracy of antenna calibration.

  • on the energy efficiency of base station sleeping with multicell cooperative transmission
    Personal Indoor and Mobile Radio Communications, 2011
    Co-Authors: Shengqian Han, Gang Wang, Chenyang Yang, Ming Lei
    Abstract:

    Switching underutilized base stations (BSs) to sleep mode is recognized as a promising approach to reduce energy consumption of cellular networks, but it may increase the transmit power of remaining active BSs to guarantee service coverage. Coordinated Multi-Point (CoMP) can effectively reduce transmit power of BSs through BS cooperation but requiring extra power consumption due to extra signal processing and backhaul traffic. In this paper, we investigate the energy efficiency of BS sleeping combined with CoMP. A joint power and subcarrier allocation algorithm is proposed to minimize the overall network power consumption with minimum data rate constraints, which can be implemented distributedly across multiple clusters. Simulation results show that BS sleeping combined with CoMP can improve network energy efficiency for high data rate users compared with Non-CoMP systems without BS sleeping.

Shengqian Han - One of the best experts on this subject based on the ideXlab platform.

  • the value of channel prediction in comp systems with large backhaul latency
    IEEE Transactions on Communications, 2013
    Co-Authors: Chenyang Yang, Shengqian Han
    Abstract:

    The potential of Coordinated Multi-Point (CoMP) transmission in providing high spectral efficiency for cellular systems largely depends on the channel quality at the cooperated base stations. In this paper, we investigate whether channel prediction is useful for downlink CoMP systems with backhaul latency in time-varying channels, where both the centralized and decentralized CoMP joint processing (CoMP-JP) as well as the CoMP Coordinated beamforming (CoMP-CB) are considered. Toward this goal, we resort to large system analysis with large number of transmit antennas to derive closed form expressions of the average per-user rate of the CoMP systems, when predicted or estimated channels are employed for downlink precoding. By comparing with Non-CoMP systems, we find that channel prediction provides much higher performance gain over channel estimation for CoMP systems, depending on the strategy of the cooperation and the user location. As a result, CoMP systems can perform fairly well for mobile users even under the large backhaul latency, if channel prediction will be used instead of channel estimation. Simulation results are provided to validate our analysis.

  • Coordinated multi point transmission strategies for tdd systems with non ideal channel reciprocity
    IEEE Transactions on Communications, 2013
    Co-Authors: Shengqian Han, Gang Wang, Dalin Zhu, Ming Lei
    Abstract:

    This paper studies transmission strategies for downlink time division duplex Coordinated Multi-Point (CoMP) systems with non-ideal uplink-downlink channel reciprocity, where several multi-antenna base stations (BSs) jointly serve multiple single-antenna users. Due to the inherent antenna calibration errors among different BSs, the uplink-downlink channels are no longer reciprocal such that the channel information at the BSs is with multiplicative noises. To mitigate the performance degradation caused by the imperfect channels, we employ a weighted sum rate estimate as the objective function for robust precoder design. To show the impact of data sharing on the performance of CoMP under the non-ideal channel reciprocity, we provide a unified framework for designing precoder for CoMP systems with different amount of data sharing. The optimal parametric linear precoder structure that maximizes the weighted sum rate estimate under per-BS power constraints is characterized, based on which a closed-form robust signal-to-leakage-plus-noise ratio (SLNR) precoder is proposed to exploit the statistics of the calibration errors. Simulation results show that the proposed precoder in conjunction with user scheduling provides substantial performance gain over Non-CoMP transmission and the CoMP transmission with non-robust precoders.

  • Coordinated multi point transmission with non ideal channel reciprocity
    Wireless Communications and Networking Conference, 2012
    Co-Authors: Shengqian Han, Gang Wang, Dalin Zhu, Ming Lei
    Abstract:

    This paper studies robust transmission strategies for downlink time division duplex Coordinated Multi-Point (CoMP) systems with non-ideal uplink-downlink channel reciprocity due to imperfect antenna calibration. By exploiting the statistics of antenna calibration errors, we first characterize the optimal parametric precoder structure that maximizes the weighted sum rate, based on which a closed-form robust signal-to-leakage-plus-noise ratio (RSLNR) precoder with properly selected parameters is then proposed. Simulation results show that the proposed precoder together with user scheduling provides near-optimal performance and data sharing among Coordinated BSs may become detrimental depending on the employed precoders and the accuracy of antenna calibration.

  • the value of channel prediction in comp systems with large backhaul latency
    Wireless Communications and Networking Conference, 2012
    Co-Authors: Chenyang Yang, Shengqian Han
    Abstract:

    The quality of channel state information (CSI) has large impact on the performance of Coordinated Multi-Point (CoMP) systems. In this paper we study the impact of channel prediction on the performance of coherent CoMP transmission in time-varying channels with large backhaul latency. We resort to large system analysis to derive an explicit expression of the average user rate of the CoMP system when predicted channels are employed for downlink precoding. By comparing with the Non-CoMP systems, we find that channel prediction brings much higher performance gain to CoMP systems with respect to channel estimation. As a result, a CoMP system can perform well for mobile users even under large backhaul latency, if channel prediction will be used instead of channel estimation. Simulation results are provided to validate our analysis.

  • on the energy efficiency of base station sleeping with multicell cooperative transmission
    Personal Indoor and Mobile Radio Communications, 2011
    Co-Authors: Shengqian Han, Gang Wang, Chenyang Yang, Ming Lei
    Abstract:

    Switching underutilized base stations (BSs) to sleep mode is recognized as a promising approach to reduce energy consumption of cellular networks, but it may increase the transmit power of remaining active BSs to guarantee service coverage. Coordinated Multi-Point (CoMP) can effectively reduce transmit power of BSs through BS cooperation but requiring extra power consumption due to extra signal processing and backhaul traffic. In this paper, we investigate the energy efficiency of BS sleeping combined with CoMP. A joint power and subcarrier allocation algorithm is proposed to minimize the overall network power consumption with minimum data rate constraints, which can be implemented distributedly across multiple clusters. Simulation results show that BS sleeping combined with CoMP can improve network energy efficiency for high data rate users compared with Non-CoMP systems without BS sleeping.

Chenyang Yang - One of the best experts on this subject based on the ideXlab platform.

  • the value of channel prediction in comp systems with large backhaul latency
    IEEE Transactions on Communications, 2013
    Co-Authors: Chenyang Yang, Shengqian Han
    Abstract:

    The potential of Coordinated Multi-Point (CoMP) transmission in providing high spectral efficiency for cellular systems largely depends on the channel quality at the cooperated base stations. In this paper, we investigate whether channel prediction is useful for downlink CoMP systems with backhaul latency in time-varying channels, where both the centralized and decentralized CoMP joint processing (CoMP-JP) as well as the CoMP Coordinated beamforming (CoMP-CB) are considered. Toward this goal, we resort to large system analysis with large number of transmit antennas to derive closed form expressions of the average per-user rate of the CoMP systems, when predicted or estimated channels are employed for downlink precoding. By comparing with Non-CoMP systems, we find that channel prediction provides much higher performance gain over channel estimation for CoMP systems, depending on the strategy of the cooperation and the user location. As a result, CoMP systems can perform fairly well for mobile users even under the large backhaul latency, if channel prediction will be used instead of channel estimation. Simulation results are provided to validate our analysis.

  • downlink base station cooperative transmission under limited capacity backhaul
    IEEE Transactions on Wireless Communications, 2013
    Co-Authors: Qian Zhang, Chenyang Yang, Andreas F Molisch
    Abstract:

    Coordinated Multi-Point transmission (CoMP) joint processing (CoMP-JP) is a promising technique for supporting high spectral efficiency in future cellular systems. However, this technique requires high-capacity backhaul links for connecting multiple base stations (BSs), which leads to high deployment costs. CoMP Coordinated beamforming (CoMP-CB) needs less backhaul capacity, but with lower maximal multiplexing gain. In this paper, we study downlink CoMP strategies with limited-capacity backhaul. We start by investigating the optimal interference-free transmission strategy under backhaul rate constraints, where only a part of the data is shared among the BSs. We then study soft and hard switching between the CoMP-JP and CoMP-CB modes. Finally, a closed-form semi-dynamic distributed hard switching scheme is proposed, which depends on the local large-scale channel gains of the users. Simulation results show that both the soft and hard mode switching transmission perform closely to the optimal strategy and outperform the single-mode CoMP transmission especially when the backhaul capacity is very limited.

  • bit allocation between per cell codebook and phase ambiguity quantization for limited feedback Coordinated multi point transmission systems
    IEEE Transactions on Communications, 2012
    Co-Authors: Fang Yuan, Chenyang Yang
    Abstract:

    Coordinated Multi-Point (CoMP) transmission is a promising technique for improving spectral efficiency of full frequency reuse cellular systems. However, its performance will be severely degraded if the feedback strategies are not carefully designed for providing channel information through limited uplink resources to the coherently cooperated base stations. In this paper, we study per-cell codebook based limited feedback scheme, which is highly desirable for CoMP systems due to its scalability and flexibility. Specifically, we investigate the issues related to phase ambiguity (PA), which comes from the per-cell codebook structure. We first analyze how many bits are required for the PA feedback to ensure an allowed performance loss. We then propose an adaptive bit allocation algorithm to divide a given amount of feedback bits between the per-cell codebooks for single-cell channel direction quantization and a codebook for PA quantization, aiming at minimizing the average global channel direction quantization error. Finally we provide a scaling law of the number of feedback bits per-user when the bit allocation algorithm is used. Simulation results show that the proposed bit allocation algorithm significantly improves the throughput of coherent CoMP systems either with equal number or different number of antennas at each base station.

  • the value of channel prediction in comp systems with large backhaul latency
    Wireless Communications and Networking Conference, 2012
    Co-Authors: Chenyang Yang, Shengqian Han
    Abstract:

    The quality of channel state information (CSI) has large impact on the performance of Coordinated Multi-Point (CoMP) systems. In this paper we study the impact of channel prediction on the performance of coherent CoMP transmission in time-varying channels with large backhaul latency. We resort to large system analysis to derive an explicit expression of the average user rate of the CoMP system when predicted channels are employed for downlink precoding. By comparing with the Non-CoMP systems, we find that channel prediction brings much higher performance gain to CoMP systems with respect to channel estimation. As a result, a CoMP system can perform well for mobile users even under large backhaul latency, if channel prediction will be used instead of channel estimation. Simulation results are provided to validate our analysis.

  • on the energy efficiency of base station sleeping with multicell cooperative transmission
    Personal Indoor and Mobile Radio Communications, 2011
    Co-Authors: Shengqian Han, Gang Wang, Chenyang Yang, Ming Lei
    Abstract:

    Switching underutilized base stations (BSs) to sleep mode is recognized as a promising approach to reduce energy consumption of cellular networks, but it may increase the transmit power of remaining active BSs to guarantee service coverage. Coordinated Multi-Point (CoMP) can effectively reduce transmit power of BSs through BS cooperation but requiring extra power consumption due to extra signal processing and backhaul traffic. In this paper, we investigate the energy efficiency of BS sleeping combined with CoMP. A joint power and subcarrier allocation algorithm is proposed to minimize the overall network power consumption with minimum data rate constraints, which can be implemented distributedly across multiple clusters. Simulation results show that BS sleeping combined with CoMP can improve network energy efficiency for high data rate users compared with Non-CoMP systems without BS sleeping.

Gang Wang - One of the best experts on this subject based on the ideXlab platform.

  • Retrieving Channel Reciprocity for Coordinated Multi-Point Transmission with Joint Processing
    IEEE Transactions on Communications, 2014
    Co-Authors: Gang Wang, Ming Lei
    Abstract:

    In time division duplex Coordinated Multi-Point transmission with joint processing (CoMP-JP) systems, the uplink-downlink channels are no longer reciprocal. Due to the difficulty of antenna calibration among the Coordinated base stations (BSs), practical downlink channels differ from uplink channels by multiplicative ambiguity factors, which lead to severe performance degradation. In this paper, we propose an inter-BS antenna calibration strategy to facilitate downlink CoMP-JP transmission, whose basic idea is to estimate the ambiguity factors. To establish the observation equations for estimation, an extra uplink training frame except for the regular uplink and downlink frames is introduced, and existing signalling framework of limited feedback can also be reused. To improve the estimation performance, we can either select multiple users or employ multiple frames of one user to assist the calibration. After establishing the observation equations respectively with uplink training or limited feedback, the weighted least square criterion is used for estimation. We proceed to analyze and compare the mean square errors of the estimators, and provide a principle to select the users for assisting calibration. Simulation results show that the channel reciprocity is largely retrieved by the proposed antenna calibration strategy, which provides substantial throughput gain over the CoMP-JP systems without inter-BS calibration.

  • Coordinated multi point transmission strategies for tdd systems with non ideal channel reciprocity
    IEEE Transactions on Communications, 2013
    Co-Authors: Shengqian Han, Gang Wang, Dalin Zhu, Ming Lei
    Abstract:

    This paper studies transmission strategies for downlink time division duplex Coordinated Multi-Point (CoMP) systems with non-ideal uplink-downlink channel reciprocity, where several multi-antenna base stations (BSs) jointly serve multiple single-antenna users. Due to the inherent antenna calibration errors among different BSs, the uplink-downlink channels are no longer reciprocal such that the channel information at the BSs is with multiplicative noises. To mitigate the performance degradation caused by the imperfect channels, we employ a weighted sum rate estimate as the objective function for robust precoder design. To show the impact of data sharing on the performance of CoMP under the non-ideal channel reciprocity, we provide a unified framework for designing precoder for CoMP systems with different amount of data sharing. The optimal parametric linear precoder structure that maximizes the weighted sum rate estimate under per-BS power constraints is characterized, based on which a closed-form robust signal-to-leakage-plus-noise ratio (SLNR) precoder is proposed to exploit the statistics of the calibration errors. Simulation results show that the proposed precoder in conjunction with user scheduling provides substantial performance gain over Non-CoMP transmission and the CoMP transmission with non-robust precoders.

  • retrieving channel reciprocity for Coordinated multi point transmission
    Wireless Communications and Networking Conference, 2013
    Co-Authors: Gang Wang, Ming Lei
    Abstract:

    Due to the difficulty of self antenna calibration among different base stations (BSs), the uplink-downlink channels are no longer reciprocal in time division duplex Coordinated Multi-Point transmission with joint processing (CoMP-JP) systems. To retrieve the channel reciprocity, we propose an inter-BS antenna calibration method. Specifically, we estimate the inter-BS ambiguity factors with weighted least square criterion by using the uplink and downlink channel estimates and the received signal of a calibration sounding signal of multiple supporting users or multiple frames. We then analyze the mean square error of the proposed estimator, and compare the performance of the estimators with multiple supporters and with multiple frames. Simulation results show that the channel reciprocity is largely retrieved by the proposed antenna calibration method, which provides substantial throughput gain over the CoMP-JP systems without calibration.

  • Coordinated multi point transmission with non ideal channel reciprocity
    Wireless Communications and Networking Conference, 2012
    Co-Authors: Shengqian Han, Gang Wang, Dalin Zhu, Ming Lei
    Abstract:

    This paper studies robust transmission strategies for downlink time division duplex Coordinated Multi-Point (CoMP) systems with non-ideal uplink-downlink channel reciprocity due to imperfect antenna calibration. By exploiting the statistics of antenna calibration errors, we first characterize the optimal parametric precoder structure that maximizes the weighted sum rate, based on which a closed-form robust signal-to-leakage-plus-noise ratio (RSLNR) precoder with properly selected parameters is then proposed. Simulation results show that the proposed precoder together with user scheduling provides near-optimal performance and data sharing among Coordinated BSs may become detrimental depending on the employed precoders and the accuracy of antenna calibration.

  • on the energy efficiency of base station sleeping with multicell cooperative transmission
    Personal Indoor and Mobile Radio Communications, 2011
    Co-Authors: Shengqian Han, Gang Wang, Chenyang Yang, Ming Lei
    Abstract:

    Switching underutilized base stations (BSs) to sleep mode is recognized as a promising approach to reduce energy consumption of cellular networks, but it may increase the transmit power of remaining active BSs to guarantee service coverage. Coordinated Multi-Point (CoMP) can effectively reduce transmit power of BSs through BS cooperation but requiring extra power consumption due to extra signal processing and backhaul traffic. In this paper, we investigate the energy efficiency of BS sleeping combined with CoMP. A joint power and subcarrier allocation algorithm is proposed to minimize the overall network power consumption with minimum data rate constraints, which can be implemented distributedly across multiple clusters. Simulation results show that BS sleeping combined with CoMP can improve network energy efficiency for high data rate users compared with Non-CoMP systems without BS sleeping.