The extreme traffic load that future wireless networks are expected to accommodate requires a rethinking of the system design. initial estimations indicate that, unlike evolutionary path previous cellular generations was based on spectral efficiency improvements, most substantial amount performance gains will be obtained by means network infrastructure densification. By increasing density operator-deployed elements along with incorporation user-deployed access nodes (ANs) and mobile user...

This paper examines the impact of system parameters such as access point density and bandwidth partitioning on performance randomly deployed, interference-limited, dense wireless networks. While much progress has been achieved in analyzing deployed networks via tools from stochastic geometry, most existing works either assume a very large user compared to that points, which does not hold network, and/or consider only signal-to-interference-ratio figure merit, provides partial insight rate...

Numerical evidence suggests that compressive sensing (CS) approaches for wideband massive MIMO channel estimation can achieve very good performance with limited training overhead by exploiting the sparsity of physical channel. However, analytical characterization (minimum) requirements is still an open issue. By observing be represented a vector not simply sparse but has well defined structural properties, referred to as hierarchical sparsity, we propose low complexity estimators uplink...

This paper addresses the problem of data detection in orthogonal frequency division multiplexing (OFDM) systems operating under a time-varying multipath fading channel. Optimal such scenario is infeasible, which makes introduction approximations necessary. The typical joint data-channel estimators are decision directed, that is, assume perfect past decisions. However, their performance subject to error propagation phenomena. variational Bayes method employed here, approximates and channel...

The problem of resource allocation (RA) in a downlink OFDMA system is examined under the realistic assumption imperfect channel state information (CSI) at base station. In this case, there nonzero outage probability that assigned rate particular subcarrier/user pair will not be supported by true realization, which may lead to significant waste system's available resources. It therefore necessary obtain RA algorithms take into account effect CSI. By exploiting statistical description CSI,...

Ultra network densification is considered a major trend in the evolution of cellular networks, due to its ability bring closer user side and reuse resources maximum extent. In this paper we explore spatial coordination as key empowering technology for next generation (5G) ultra-dense networks. We propose an optimization framework flexibly associating system users with access nodes densely deployed network, opting exploitation control overhead signaling. Combined precoding strategies,...

Exploiting massive multiple-input-multiple-output (MIMO) gains come at the expense of obtaining accurate channel estimates base station. However, conventional estimation techniques do not scale well with increasing number antennas and incur an unacceptably large training overhead in many applications. This calls for designs that efficiently exploit physical properties MIMO as captured by sophisticated system/channel models. In this paper, we present sparsity angle delay domain representation...

Ultra network densification and Massive MIMO are considered major 5G enablers since they promise huge capacity gains by exploiting proximity, spectral spatial reuse benefits. Both approaches rely on increasing the number of access elements per user, either through deploying more nodes over an area or antenna node. At network-level, optimal user-association for a densely randomly deployed empowered must account both channel load conditions. In this paper we formulate complex problem, report...

An important enabler towards the successful deployment of any new element/feature to cellular network is investigation and characterization operational conditions where its introduction will enhance performance. Even though there has been significant research activity on potential device-to-device (D2D) communications, are currently no clear indications whether D2D communications actually able provide benefits for a wide range conditions, thus justifying their system. This paper attempts...

We study the problem of indoor localization using commodity WiFi channel state information (CSI) measurements. The accuracy methods developed to address this is limited by overall bandwidth used device as well various types signal distortions imposed underlying hardware. In paper, we propose a method that performs impulse response (CIR) estimation splicing measured CSI over multiple bands. order overcome hardware-induced phase distortions, retrieval (PR) scheme only uses magnitude values...

Using commodity WiFi data for applications such as indoor localization, object identification and tracking channel sounding has recently gained considerable attention. We study the problem of impulse response (CIR) estimation from state information (CSI). The accuracy a CIR method in this setup is limited by both available bandwidth well various CSI distortions induced underlying hardware. propose multi-band splicing that increases combining across multiple frequency bands. In order to...

This paper considers the problem of analytically assessing maximum achievable rates (capacity) orthogonal frequency division multiplexing (OFDM) transmissions when receiver, for complexity reasons, only accounts common phase error (CPE) effect due to noise impairments with inter-carrier interference (ICI) treated as noise. By recognizing that functional form CPE respect realization is actually a free design parameter, determination capacity posed optimization the, so-called, function. A...

Current application of carrier aggregation (CA), a key enabling technology for wideband communications over fragmented spectrum, is limited to only small number component carriers (CCs). However, wireless broadband connectivity future networks requires the exploitation multiple, contiguous, and non-contiguous CCs (NC-CCs). By considering large aggregated NC-CCs, concept massive CA (NC-CA) realized, which offers highest flexibility in spectrum aggregation. In order fully exploit system-level...

An important enabler towards the successful introduction of any new element/feature to cellular network, such as ability allow for direct, device-to-device (D2D) communications, is investigation and characterization operational conditions, e.g., density users, where its deployment will enhance performance. This paper attempts provide a mathematically rigorous set (region) which overlay D2D communications performance in terms average user rate. Using tools from stochastic geometry,...

A new, reduced complexity algorithm is proposed for compensating the Inter-Carrier Interference (ICI) caused by severe PHase Noise (PHN) and Residual Frequency Offset (RFO) in OFDM systems. The estimates compensates most significant terms of frequency domain ICI process, which are optimally selected via a Minimum Mean Squared Error (MMSE) criterion. requires minimal knowledge phase process statistics, estimation also considered. scheme outperforms previously compensation methods similar...

The problem of resource allocation (RA) in a downlink OFDMA system with minimum user rate requests is examined under the realistic scenario partial (imperfect) channel state information (CSI) at base station. challenge this setting non-zero probability outage events which may lead to significant performance degradation if algorithms assuming perfect CSI are utilized. In paper statistical description incorporated for deriving an (optimal) RA algorithm as solution appropriate constrained...

Optimal resource allocation (RA) in massive carrier aggregation scenarios is a challenging combinatorial optimization problem whose dimension proportional to the number of users, component carriers (CCs), and OFDMA blocks per CC. Toward scalable, near-optimal RA CA settings, an iterative algorithm proposed for joint assignment CCs users. The based on principle successive geometric programming approximations has complexity that scales only linearly with dimension. Although its derivation...

Recent trends in wireless networking such as small cells and network function virtualization, strongly suggest that the future cellular will consist of many sub-networks controlled by self-interest operators competing for a share revenues associated with high demand service. This paper attempts to analyze performance under these new market conditions, taking into account not only engineering properties sub-networks, e.g., spectral efficiency, but economic well, i.e., service pricing. Going...

Advances in cellular networks such as device-to-device communications and full-duplex radios, well the inherent elimination of intra-cell interference achieved by network-controlled multiple access schemes, motivate investigation cross-mode properties under a guard region corresponding to Voronoi cell an point (AP). By modeling positions interfering APs user equipments (UEs) Poisson distributed, analytical expressions for statistics generated either or UEs are obtained based on appropriately...

This paper addresses the problem of data detection in OFDM systems operating under a time-varying multipath fading channel. Optimal such scenario is infeasible, which makes introduction approximations necessary. The variational Bayes method employed here, approximates joint and channel distribution as separable one, greatly simplifying problem. part resulting algorithm provides soft estimates that are used for tracking. itself modeled an auto-regressive process allowing Kalman-like tracking...

Recent trends in wireless networking, such as small cells and network function virtualization, strongly suggest that the future cellular will consist of many sub-networks controlled by self-interest operators competing for a share revenues associated with high demand service. This paper attempts to analyze performance under these new market conditions, considering not only engineering properties sub-networks, i.e., achievable rate, but economic well, service pricing. Using game-theoretic...

We consider minimum mean squared error (MSE) channel estimators operating on the basis of time-frequency signal observations comprising mixtures known pilot and unknown data signals. These are useful for a general class receivers resorting to representation received - obtained by, e.g., filter bank which have recently been considered in context reconfigurable radio. Taking advantage Kronecker product properties we derive two-dimensional formulations doubly-dispersive estimation, afford...

In this paper, analytical assessment of overlay-inband device-to-device (D2D) communications is investigated, under cellular-network-assisted (coordinated) scheduling. To end, a simple scheduling scheme assumed that takes into account only local (per cell) topological information the D2D links. Stochastic geometry tools are utilized in order to obtain expressions for interferers density as well link signal-to-interference-ratio distribution. The results accuracy validated by comparison with...