Search results for: Shengqian Han
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IEEE Transactions on Communications > 2017 > 65 > 12 > 5559 - 5573
Recent work has demonstrated the gain of full-duplex (FD) network over half-duplex (HD) network in bidirectional sum throughput under the assumption of symmetric uplink-downlink traffic demands and perfect self-interference suppression (SIS). In this paper, we study the performance gain of FD network over HD network under asymmetric bidirectional traffic demands and non-ideal SIS. To this end, we...
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IEEE Transactions on Wireless Communications > 2017 > 16 > 7 > 4288 - 4303
In this paper, we consider the design of analog beamformers for the downlink of multi-user massive multiple-input-multiple-output (MIMO) systems. We specifically investigate systems, where both link ends are equipped with hybrid digital/analog beamforming structures, where the analog beamformers are adapted based on second order channel statistics, reducing the training overhead as well as hardware...
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In this paper, we consider the design of analogue beamformers for the downlink of multi-user massive multiple-input-multiple-output (MIMO) systems. We specifically investigate systems where both link ends are equipped with hybrid digital/analog (HDA) beamforming structures, where the analog beamformers are adapted based on second order channel statistics, reducing the training overhead as well as...
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Caching popular contents at the base stations is an effective way to address the challenging data traffic demand driven by video-on-demand (VoD) service. Initial delay is one of the most important factors affecting the quality of experience (QoE) of users for VoD service. Existing work has optimized the caching policy to reduce the average delay for file downloading service. However, considering the...
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IEEE Communications Magazine > 2017 > 55 > 9 > 134 - 141
Hybrid multiple-antenna transceivers, which combine large-dimensional analog pre/postprocessing with lower-dimensional digital processing, are the most promising approach for reducing the hardware cost and training overhead in massive MIMO systems. This article provides a comprehensive survey of the various incarnations of such structures that have been proposed in the literature. We provide a taxonomy...
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This paper studies the bidirectional user scheduling and mode selection in single-cell full-duplex (FD) system, where a FD base station (BS) serves multiple uplink and downlink half-duplex (HD) users. Due to the existence of the inter-user interference from an uplink transmitting user to a downlink receiving user, the system operating in FD mode does not necessarily outperform HD mode, depending on...
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This paper studies the energy efficient optimization for full duplex (FD) assisted closed-loop downlink transmission, where a FD base station (BS) serves multiple half duplex (HD) users in a time division multiple access manner. We optimize the durations of uplink training and downlink transmission, aimed at maximizing the energy efficiency (EE) of the system. We first show that the EE-optimal transmission...
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This paper studies the mitigation of cross-tier inter-cell interference (ICI) generated by a macro base station to a small-cell user equipment (SUE) in heterogeneous networks. A full-duplex (FD) based successive ICI cancellation (SIC) scheme, called fSICIC, is devised by applying FD technique at the small-cell base station (SBS). The basic idea of the fSICIC is to let the SBS send the desired signal...
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Full duplex assisted inter-cell interference coordination (fICIC) has been shown effective to mitigate the cross-tier inter-cell interference (ICI) generated by the macro-cell base station (MBS) to the small-cell user equipment (SUE) in downlink narrowband heterogeneous networks. The fICIC applies full duplex technique at the small-cell BS (SBS) such that the SBS can forwarded the overheard ICI to...
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In this paper, we consider the design of two-stage beamformers for the downlink of multi-user frequency-division-duplexing (FDD) massive multiple-input multiple-output (MIMO) systems. We consider the case that both link ends are equipped with hybrid analog/digital (HDA) beamforming structures. With analog beamforming and user grouping based on the second-order channel statistics, the user equipment...
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Recent work has demonstrated the advantage of full-duplex (FD) network over half-duplex (HD) network in bidirectional sum rate under the assumption of full-buffer and symmetric uplink-downlink traffics. In this paper, we consider asymmetric bidirectional traffics, and study the performance gain of FD network over both the traditional time-division duplex (TDD) network with static time slot splitting...
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IEEE Transactions on Vehicular Technology > 2016 > 65 > 4 > 2063 - 2077
This paper studies user-specific clustering for a downlink cloud radio access network (C-RAN), where a central unit (CU), connected to all base stations (BSs) via limited-capacity backhaul links, coordinates the BSs to form cooperative clusters for every user. By taking into account the training overhead for channel estimation in C-RAN, we design the clustering scheme aimed at maximizing the average...
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IEEE Transactions on Communications > 2017 > 65 > 1 > 107 - 121
Massive multi-input multi-output (MIMO) can support high spectral efficiency with simple linear transceivers, and is expected to provide high energy efficiency (EE). In this paper, we analyze the scaling laws of EE with respect to the number of antennas $M$ at each base station of downlink multi-cell massive MIMO systems under spatially correlated channel, where both transmit and circuit power consumptions,...
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IEEE Transactions on Communications > 2015 > 63 > 12 > 5218 - 5234
This paper studies the suppression of cross-tier intercell interference (ICI) generated by a macro base station (MBS) to pico user equipments (PUEs) in heterogeneous networks (HetNets). Different from existing ICI avoidance schemes such as enhanced ICI cancellation (eICIC) and coordinated beamforming, which generally operate at the MBS, we propose a full duplex (FD)-assisted ICI cancellation (fICIC)...
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This paper studies wideband hybrid precoder for downlink space-division multiple-access and orthogonal frequency-division multiple-access (SDMA-OFDMA) massive multi-input multi-output (MIMO) systems. We first derive an iterative algorithm to alternatingly optimize the phase-shifter based wideband analog precoder and low-dimensional digital precoders, then an efficient low-complexity non-iterative...
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Recent studies have demonstrated the effectiveness of proactive resource allocation under the assumption of perfect prediction of the user's future data rate. In this paper, imperfect rate prediction merely based on the context information including large-scale channel gains of users and statistical information of system available resources is considered. Under the outage-based quality of service...
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Hybrid architecture has been shown to be cost effective for massive multi-input multi-out (MIMO) systems, where analog precoder is used to form narrow beams towards users for data transmission with reduced number of radio frequency chains. However, besides the user-specific data, a wideband massive MIMO system needs to broadcast control signaling intended for all users simultaneously, which requires...
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The paper considers underlay Device-to-Device (D2D) communications in a cellular network, where a pair of D2D users communicates subject to the interference from the base station that is transmitting to a cellular user in the downlink. To mitigate the interference while not affecting the performance of the cellular user, a full duplex (FD) assisted interference suppression mechanism is introduced...
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In this paper, we compare the average energy efficiency (EE) of massive MIMO system and small cell network (SCN) under the conditions of identical user density, antenna density and data rate requirements, where the uplink and downlink training overhead as well as multi-cell power control are taken into account. Our analysis shows that the average transmit power of SCN decreases faster than massive...
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This paper studies downlink coordinated beamforming schemes with overlapped clusters, where a base station (BS) may belong to multiple clusters selected by different users. Subject to the inherent constraint on information sharing for overlapped clusters, i.e., the information of a user is shared only within the user's coordinating cluster, we propose two decentralized coordinated beamforming schemes,...
