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In a multi-cell wireless network, users require to be properly assigned to base-stations. After assigning the base-stations to users, the power consumption and interference is controlled by means of a distributed power control algorithm. The power control and base station assignment is a challenging issue which should be jointly addressed. The conventional target-SINR tracking power control algorithm...
In this paper we propose a joint dempster-shafer (DS) detection for superposition modulation (SPM) in a non-orthogonal multiple access channel with multiple antenna configuration. Signals from different users are modulated with user-specific modulation factors and then multiplexed for transmission. At the receiver, the DS joint detection recovers all users' information simultaneously based on the...
In this paper, we study optimal transmission scheduling and congestion control in multi-hop device-to-device (D2D) communications underlaying cellular networks. The optimization is not only based on the cellular and D2D link qualities but it also takes the interference situation for each possible mode and the quality of service (QoS) requirements of each user into account. The problem is formulated...
This paper presents a framework for coverage and capacity optimization (CCO) in Heterogeneous Cellular Networks (HCNs). Unlike conventional approaches, we propose a concept of effective capacity (EC) as the optimization objective of CCO, which involves the index of coverage in the form of truncation function. The optimization objective is a NP problem due to that the adjusting parameters are mixed...
Small cell networks are the key to the success of the next generation wireless systems because of the potential huge capacity gain, but pose many challenges on managing the inter-cell interference from huge number of small cells and that from macrocells. Recently, an interesting technique, called interference alignment (IA), was proposed to align the mutual inter-cell interference (ICI) in the same...
In this paper, we discuss the precoding schemes for coordinated multi-point (CoMP) joint processing (JP) using geometric mean decomposition (GMD). Unlike JP singular value decomposition (JP-SVD) whose performance is dominated by the spatial pipe with weak channel gain, JP-GMD is proposed to derive the precoding matrix of all the cooperative cell sites and the decoding matrix of the user equipment...
Interference alignment (IA) is a scheme to achieve degrees of freedom (DOF) of interference network at high signal-to-noise ratio (SNR). In order to implement IA scheme in frequency-division duplexing (FDD) system, receivers feedback channel state information to transmitters. The key problem is to acquire accurate transmitter channel state information (CSIT) in the presence of the quantization error...
This paper considers a joint beamforming design problem in the multicell multicast system with multiple groups that provide different multicast services. Inspired by previous works in the literature, we apply semidefinite relaxation (SDR) to perform joint beamforming design among the cooperating base stations. Per-cell power constraints are considered which make solving the problem challenging. We...
The deployment of small cell base stations (SCBSs) overlaid on existing macro cellular networks can potentially improve the coverage and capacity of cellular wireless systems. However, a massive deployment of SCBSs also leads to an undesirable increase in energy consumption and severe intratier and inter-tier interference. In this paper, the joint design of discontinuous transmission (DTX) and power...
This paper considers the model that two mobile users communicate with a central processer (CP) via two base stations (BSs). The BSs are connected to the CP via orthogonal finite-capacity links. The theoretical capacity of this model is still an open problem. For given capacity of backhaul links, we use private message, common message and joint decoding message to explore a new achievable rate. We...
Caching at wireless access points is a promising approach to alleviate the backhaul burden in wireless networks. In this paper, we consider a cooperative wireless caching network where all the base stations (BSs) are connected to a central controller via backhaul links. In such a network, users can get the required data locally if they are cached at the BSs. Otherwise, the user data need to be assigned...
The data traffic volumes are constantly increasing in cellular networks. Furthermore, a larger part of the traffic is generated by applications that require high data rates. Techniques including Coordinated Multipoint transmission (CoMP) can increase the data rates, but at the cost of a high overhead. The overhead can be reduced if only a subset of the users is served with CoMP. In this paper, we...
The successful deployment of LTE heterogeneous networks (HetNets) depends crucially on the inter-cell interference (ICI) management. Among ICI coordination schemes, fractional frequency reuse (FFR) is considered as an efficient technique well-suited to OFDMA-based HetNets. Two coupled questions in this context are: 1) how to associate users to appropriate basestations considering the long list of...
The accuracy of the estimation of time-delay and channel coefficients in Orthogonal frequency division multiplexing (OFDM) communication systems can be improved by reducing the variability of channel coefficients, i.e. reducing channel covariance and increasing channel mean for a given power. First, we prove that the effect of channel variability between different OFDM symbols cannot be directly captured...
Ultra network densification is considered a major trend in the evolution of cellular networks, due to its ability to bring the network closer to the user side and reuse resources to the maximum extent. In this paper we explore spatial resources coordination as a key empowering technology for next generation (5G) ultra-dense networks. We propose an optimization framework for flexibly associating system...
In this paper, a novel cluster-based approach for optimizing the energy efficiency of wireless small cell networks is proposed. A dynamic mechanism based on the spectral clustering technique is proposed to dynamically form clusters of small cell base stations. Such clustering enables intra-cluster coordination among the base stations for optimizing the downlink performance through load balancing,...
Inter-cell interference in LTE-Advanced can be mitigated using coordinated multi-point (CoMP) techniques with joint transmission of user data. However, this requires tight coordination of the eNodeBs, using the X2 interface. In this paper we use discrete-event simulation to evaluate the latency requirements for the X2 interface and investigate the consequences of a constrained backhaul. Our simulation...
Interference alignment (IA) is a scheme to approach the capacity at high signal-to-noise ratio (SNR) in multiuser multiple-input multiple-output (MIMO) interference networks. To implement the IA scheme in a frequency-division duplexing (FDD) system, transmitter channel state information (CSIT) is fed back from the receiver with finite bits. However, such CSIT is subject to quantization errors and...
This paper studies the suspension control problem of permanent magnetic and electromagnetic hybrid high-speed maglev train under different fault condition. The suspension system model with joint structure is established. The linear quadratic optimal control theory is applied to implement the control algorithm design. The simulation analyzes multiple possible failure conditions of the joint joint structure...
In this paper, we consider a two way cognitive relay network using decode and forward (DF) protocol over Rayleigh fading channels. Under the joint outage constraint of the primary user (PU) caused by a pair of secondary transmitters (ST) and the secondary relay (SR), the problem of power allocation for the secondary users (SU) is reformulated. We derive the optimal power allocation algorithm for the...
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