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The capacity of frequency-flat multiuser MIMO downlinks is achieved with nonlinear dirty paper coding (DPC). Linear processing techniques, such as block diagonalization (BD), offer relatively low computational cost with respect to DPC and can also achieve capacity in certain cases. However, BD is not easily translated to frequency-selective channels since the channel matrix has a space-time structure...
The Radio Access Network based on Fog computing (F- RAN) has been recently proposed to alleviate the heavy burden on backhauls of Cloud Radio Access Network (C-RAN). Equipping the edge device of C-RAN with local storage module (cache) is a specific realization of F-RAN. Some frequently requested files are cached at the Radio Units (RUs), both the traffic load and the overall delay can be reduced....
This paper proposes a full-duplex physical security model with self-interference remaining. This model doesn't need the assistance of external jamming nodes and it ensures that the uplink and downlink transmission of the full-duplex system can achieve the required secrecy rate. Meanwhile, it creates a base station transmission power optimization problem with flexible constraints and a two-level method...
In this paper, we consider a cloud radio access network (CRAN) with full duplex (FD) remote radio heads (RRHs) and half duplex mobile users. Compared with half duplex RRHs, though FD-RRHs can simultaneously transmit and receive data streams, they also suffer from new interference sources such as self-interference and inter-RRH interference. With FDRRHs, the downlink mobile users (DMUs) are also interfered...
We study the joint optimization of resource allocation and user association in downlink multi-antenna heterogeneous networks. The resource allocation is done orthogonally in the spectrum while the user association is implemented using cell range extension. The objective is to maximize a user utility function that depends on the rate of the typical user. We resort to the Gil-Pelaez Inversion Theorem...
In this paper, a joint linear pre-coder and combiner optimization scheme is proposed to reduce the multi- user interference in the distributed antenna system (DAS). The pre-coder is designed based on the modified weighted signal-to-caused interference ratio (SCIR) which considers the interference on others caused by the desired user and the users channel condition. And the combiner is chosen based...
Massive multiple-input multiple-output (MIMO) is one of the promising technologies to be used in the future fifth generation (5G) wireless networks for its capability to increase the system throughput, improve spectral efficiency and energy efficiency. To achieve these benefits of the massive MIMO, there are many challenges that need to be handled. One of these challenges is the pilot contamination...
Given the increasing importance of mobile data access, extending broadband wireless access has become a global grand challenge. Relaying has been introduced to enable wireless communication between users lacking a common link. Distributed relay networks (DRN) are a special case where the relay consists of many geographically distributed single-antenna nodes to achieve spatial diversity. In this paper...
In this paper, we propose joint spectral shaping and power allocation for an orthogonal frequency division multiplexing (OFDM)-based cognitive radio (CR). The objective is to maximize its downlink transmission rate subject to the constraint on the interference introduced to the primary user (PU) spectrum band that coexists side-by-side in overlay approach. Considering that the CR transmitter (base...
Downlink/Uplink decoupling (DUDe) in LTE networks has caught the attention of researchers as it provides better uplink SINR and reduced power consumption per device due to decoupled connection of a device with the Macro (in downlink) and a small cell (in uplink). These characteristics of DUDe can be exploited to encourage more D2D communications in the network. This paper first proposes a model to...
We develop an interference alignment technique, called cyclic IA, for full-duplex (FD) multiple-input multiple-output (MIMO) cellular networks in which a base station (BS) that operates in FD mode supports a set of half-duplex (HD) uplink and downlink users simultaneously. The key idea behind our approach is to construct a set of loop-equations enabling interference alignment, so that beamforming...
A two-stage beamforming (BF) approach is proposed for millimeter wave (mmWave) cellular networks, wherein each base station (BS) first obtains wide beams to its users during the initial access (IA), then refines to narrow beams during the beam refinement phase (BRP). The performance of the proposed approach is derived under three IA protocols. Compared to a single-stage approach where beam searching...
A two-stage downlink beamforming design is proposed for multicell multi-input single-output channels with limited backhaul capacity and local channel state information (CSI). The first stage is to maximize the signal-to-leakage-plus-noise ratio with local CSI. Each base station (BS) then calculates the corresponding channel gains and shares them with all other BSs, which typically requires low-rate...
User association and resource allocation for downlink orthogonal frequency division multiplexing (OFDM) should be jointly optimized in small cells networks with limited backhaul in order to maximize the network utility. In general, the joint user association and per-band resource allocation problem is known as an integer NP-hard problem requiring exponential order of computational complexity to find...
Spectrum scarcity is one of the most discussed limiting factors in wireless communication systems. To solve this issue heterogeneous network (HetNets) is introduced. It is a promising development to fulfil the requirement of Long Term Evolution (LTE) and Long Term Evolution Advanced (LTE-A). With the introduction of HetNets comes femtocell which arises the problem of Inter Cell Interference (ICI)...
In heterogeneous networks (HetNets) users are usually distributed non-uniformly. Analysis of the impact of nonuniformity of user distribution on HetNets is essential for designing efficient networks. This paper proposes a non-uniform user distribution model in which the user density depends on the distance to the associated base stations (BSs). Moreover, different tiers, such as macro cells, pico...
Military satellite communication (SATCOM) on-the-move (SOTM) is vulnerable for intentional and unintentional interference either from terrestrial or satellite jammers. The use of multiple receive antennas at satellite level or on ground provides the possibility for a more robust and secure transmission of sensitive data. In this paper, the performance of maximum-ratio combining (MRC) for multiple...
Decoupling uplink (UL) and downlink (DL) is a new architectural paradigm where DL and UL are not constrained to be associated to the same base station (BS). Building upon this paradigm, the goal of the present paper is to provide lower, albeit tight bounds for the ergodic UL capacity of a decoupled cellular network. The analysis is performed for a scenario consisting of a macro BS and a set of small...
Wireless networks will become more heterogeneous in next generation (5G). We need good models for the spatial distribution of base station (BS) and user equipment (UE) to perform accurate analysis of heterogeneous networks (hetnets). The literature on hetnets UE modeling that includes spatial dependency is still rather limited. In this paper, we introduce a nonuniformly distributed UE model based...
This paper discusses the modeling and analysis of throughput in the multi-tier heterogeneous networks with a focus on downlink. We first derive a closed-form solution for downlink probability of coverage based on max-SINR association policy in a multi-tier network with orthogonal spectrum allocation among tiers and then compute the throughput of the network considering user mobility. More specifically,...
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