A joint transmission point selection and precoding scheme is proposed herein to mitigate interference in a C-RAN system with distributed fronthaul-constrained transmission points. Two methods are proposed to deal with...
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A joint transmission point selection and precoding scheme is proposed herein to mitigate interference in a C-RAN system with distributed fronthaul-constrained transmission points. Two methods are proposed to deal with the original NP-hard problem. First, reformulation into convex form is done using an upper bound method, where tightness of the bound and its implication on system scenario are easy to establish. The second one uses successive convex approximation to approximate the nonconvex constraint and is shown to maximize spectral efficiency at the expense of higher computational complexity compared to the first approach. Numerical results will show the efficacy of the proposed approaches.
In this paper, we investigate broad coverage precoder design for 3D massive multi-input multi-output (MIMO) systems. We focus on the synchronization performance in the cell coverage. The log-distance path loss model i...
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ISBN:
(纸本)9781728150895
In this paper, we investigate broad coverage precoder design for 3D massive multi-input multi-output (MIMO) systems. We focus on the synchronization performance in the cell coverage. The log-distance path loss model in the line-of-sight (LoS) scenario is formulated. The synchronization performance can be characterized by the missed detection (MD) probability. By considering the equal MD probability in the cell, we formulate a criterion for the precoder design. Moreover, we consider the equal transmit power constraint on each antenna to efficiently utilize the power amplifier (PA) capacity of the BS. By using the manifold optimization framework, we design the precoder under the aforementioned criterion and constraint. Simulation results show that the fairness among all the users in this cell can be ensured. Compared with the precoders designed by half power beam-width (HPBW), the proposed scheme causes much less inter-cell interference, and has a better synchronization performance.
In this paper, we investigate the precoder design for MIMO multicasting, where two data streams are sent from the transmitter and the minimum mean-squared-error decision feedback equalizer is performed at all users. T...
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ISBN:
(纸本)9781479903061
In this paper, we investigate the precoder design for MIMO multicasting, where two data streams are sent from the transmitter and the minimum mean-squared-error decision feedback equalizer is performed at all users. To improve the receiving quality of data streams, we focus on maximizing the minimal signal-to-interference-plus-noise ratio (SINR) for all streams via precoding. Considering that the precoder is composed of a transformation matrix and a rotation matrix, we separate the precoder design into two stages. Firstly we calculate the transformation matrix under the criterion of maximizing the throughput of the multicast channel. Then, by deriving the relationship between the rotation matrix and the SINR, we transform the original problem into a real-valued optimization problem, and moreover, a Lozano's algorithm is proposed to compute the rotation matrix. In particular, for the special case of two users, a constructive method can be applied to directly calculate the rotation matrix. The simulation results show that the proposed design outperforms the existing ones in both the achievable rate and symbol error rate.
In this paper, we propose a novel methodology to design optimal precoders for distributed detection of high-dimensional signals. We consider a wireless sensor network (WSN) that consists of multiple sensors that are s...
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In this paper, we propose a novel methodology to design optimal precoders for distributed detection of high-dimensional signals. We consider a wireless sensor network (WSN) that consists of multiple sensors that are spatially distributed in a region of interest and a fusion center (FC). The sensors observe an unknown high-dimensional signal and forward their observations to the FCafter precoding. The sensors collect data over both temporal and spatial domains. The FC performs a binary hypothesis test based on the data received fromthe sensors over noisy channels. In this setup, we present a technique to design optimal online linear precoding strategies with transmit power constraints. We show analytically that the error exponents achieved by the proposed precoders are independent of the signal dimension. In contrast, the error exponents of the state-of-the-art precoding strategies deteriorate with the increase in signal dimension. We verify our analysis via numerical simulations and show that the proposed precoders achieve better detection performance compared to those of other state-of-the-art techniques known in the literature.
In this paper, we design the precoding matrix with broad coverage for massive multi-input multi-output public channels. In order to guarantee the efficient use of power amplifiers and improve the achievable ergodic ra...
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In this paper, we design the precoding matrix with broad coverage for massive multi-input multi-output public channels. In order to guarantee the efficient use of power amplifiers and improve the achievable ergodic rate, equal transmit power per-antenna and semi-unitary constraints on the precoding matrix are considered simultaneously. Within the framework of manifold optimization, the precoding matrix design under the above two constraints becomes an optimization problem over the intersection of the oblique manifold and the Stiefel manifold. We propose to use the steepest descent method on the intersection of these two manifolds to obtain the optimal solution. By using the alternating projections method, the search direction of the steepest descent method is derived. Meanwhile, the convergence analysis for the proposed approach is also provided. The proposed approach can be used for both omnidirectional and sector-shaped power pattern design. Simulation results show that the power pattern of our designed precoder has less variation in different spatial directions within the cell coverage compared with the existing Zadoff-Chu scheme.
In the dense small cell networks, CoMP is an efficient way to improve transmission rate. Unfortunately, CoMP would increase the backhaul resource consumption, which is not trivial for the small cell networks with limi...
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In the dense small cell networks, CoMP is an efficient way to improve transmission rate. Unfortunately, CoMP would increase the backhaul resource consumption, which is not trivial for the small cell networks with limited wireless backhaul. On the other hand, the small cell base stations can cache locally some files in advance to alleviate the payload on backhaul. In this paper, we study the effect of distributed caching and the limited backhaul resources on the design of CoMP, and propose a CoMP precoding design method, which can be performed in a distributed way. Our simulation results show that considering both backhaul and caching is important for designing the appropriate CoMP precoding, and our proposed method produces higher throughput than the existing CoMP precoding design scheme.
In cognitive radio communications, the coexistence of a secondary network is allowed as long as the interference power from the secondary network measured at the primary user (PU) is kept below a given threshold. In t...
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In cognitive radio communications, the coexistence of a secondary network is allowed as long as the interference power from the secondary network measured at the primary user (PU) is kept below a given threshold. In this paper, we consider a communication scenario for cognitive radio networks where the channel state information (CSI) between the secondary base station (SBS) and the PU is perfectly known at the SBS transmitter whereas only the covariance information is known for the channel of the SBS-secondary user (SU) link at the SBS transmitter. A closed-form precoder design method is proposed for the purpose of maximizing the upper bound of the expected achievable rate of the SU. Even though the proposed scheme uses only partial CSI of the SBS-SU link, the simulation results show that the expected achievable rate of the proposed scheme approaches to that of a conventional scheme with full CSI as the channel correlation increases. (C) 2012 Elsevier B.V. All rights reserved.
Spectrum sharing between radar and cellular communication systems has been proposed by spectrum regulatory agencies for achieving more efficient use of spectrum. Enabling such sharing requires strategies that control ...
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ISBN:
(纸本)9781728123769
Spectrum sharing between radar and cellular communication systems has been proposed by spectrum regulatory agencies for achieving more efficient use of spectrum. Enabling such sharing requires strategies that control the interference between the two systems. A cooperative approach for spectrum sharing between a MIMO radar and a MIMO communication system has been recently proposed, in which, cooperation is supervised by a controller, who collects information from both system and designs a precoding scheme for the communication system so that it interferes minimally with the radar. However, the precoding matrix contains implicit information about the radar, and could be used by an adversary to violate the radar's privacy. In this paper, we show how the radar angle with respect to the communication unit can be estimated based on the precoding matrix. We also propose a precoder design approach considering the trade off between the interference power and radar privacy. The proposed approach obfuscates the radar location at the cost of a slight increase in the interference power to the radar.
This paper deals with the design of a hybrid precoder for millimeter-wave MIMO systems. For the sake of concreteness, we consider an analog processing stage composed of a switching network with analog combining. The m...
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ISBN:
(纸本)9789082797039
This paper deals with the design of a hybrid precoder for millimeter-wave MIMO systems. For the sake of concreteness, we consider an analog processing stage composed of a switching network with analog combining. The main contribution of this work consists on the proposal and evaluation of an optimization procedure based on a smart relaxation. The optimal hybrid precoder under a transmit power constraint is derived, after which, the analog precoding matrix is binarized. After an intuitive reasoning, we note that multiple solutions exist. Nevertheless, the (very) reduced computational complexity of the proposed optimization scheme makes it feasible for realistic implementations. Numerical results are reported to assess the performance of proposed hybrid precoder design.
We study a cellular system scenario where multiple data streams originating from a base station (BS) targeted to multiple cell-edge mobile stations (MSs) are transmitted via pre-installed cooperative relay stations (R...
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We study a cellular system scenario where multiple data streams originating from a base station (BS) targeted to multiple cell-edge mobile stations (MSs) are transmitted via pre-installed cooperative relay stations (RSs) with multiple antennas. Our objective is to guarantee quality-of-service (QoS) in terms of predefined signal-to-noise ratio at such users within the transmit power budgets at BS and RSs while minimizing total transmit power. We propose a novel precoder design method for power allocation between multiple data streams at BS and RS by using joint zero-forcing strategy in order to avoid multiuser interference (MUI) in the signal received by MSs via both the direct and relay links. We also propose low-complexity suboptimal power allocation algorithm. We focus on analyzing the significance of direct link transmission in providing QoS to cell-edge MSs specially when RS is not situated directly between BS and MSs. Simulation results show that considering direct link and using the proposed scheme in such case significantly improves system outage performance compared to existing schemes in the literature which do not consider direct link.
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