1,721,005 research outputs found
AeroMACS: A new perspective for mobile airport communications and services
No full textBroadband wireless technologies are becoming more and more pervasive in several fields of application to supply new services and to satisfy operational constraints. Among them, this paper deals with the use of WiMAX technology in future air traffic management system. This technology is expected to increase the safety and to allow the exchange of large volume of data among heterogeneous users, including aircrafts. In particular,
Eurocontrol and ICAO identified a WiMAX based technology for communications on the airport surface, named Aeronautical Mobile Airport Communication System (AeroMACS). The scope of this paper is to provide an overview of AeroMACS, with a description of its main features, requirements, PHY and MAC profiles choices and related network architecture. Finally, the paper highlights some open issues for AeroMACS that represent critical aspects and require, up to now, additional investigations
Resource Allocation Approaches for Two-Tiers Machine-to-Machine Communications in an Interference Limited Environment
No full textOne of the main challenges of supporting massive machine type communications by future mobile network, is the radio access network congestion.
A viable solution is a hierarchical architecture where cluster-grouped machines are indirectly connected to the mobile network through a cluster gateway.
This paper considers such an architecture and focuses on radio resource allocation to machine-clusters where resources can be spatially reused for concurrent transmissions.
In particular, resources can be accessed simultaneously by machines of different clusters and by different communication phases, thus resulting in an interference-limited system.
Three different resource partitioning schemes are proposed and evaluated, mainly differing on how interference is taken into account.
The aim is to minimize the packet loss probability, and thus maximizing the spectral efficiency.
Numerical results show the effectiveness of the proposed schemes in comparison to benchmark methods.
In particular, by joining resource reuse and interference-mitigation, the efficiency improves significantly
Low-Complexity Distributed Cell-Specific Bias Calculation for Load Balancing in UDNs
No full textThe challenge of the fifth generation (5G) of wireless systems is to overcome fundamental limits of existing cellular networks by means of advanced technologies such as network densification.
Nevertheless, dense and random deployment of the network infrastructure poses new challenges in the network management.
In particular, rethinking cell association policies and introducing new specific load balancing strategies will be mandatory to shift traffic from heavy loaded cells to light loaded neighbors.
Toward this goal, cell biasing is considered one of the most effective way.
This paper proposes a low complexity distributed cell-specific bias algorithm suitable for an actual implementation on highly dense scenarios.
This solution takes into account the users' data rate requests and aims at minimizing the outage-rate defined as the amount of unsatisfied data rate requests.
Numerical results show that despite its low complexity, the solution achieves performance only slightly lower than the benchmark near-optimum solution
The Structure and Performance of an Optimal Continuous-Time Detector for Laplace Noise
No full textA optimal detector for a known signal in Laplace noise is determined. The analysis starts with a sampled digital receiver, leading to an asymptotic analysis when the number of samples approaches infinity. The optimum detector for Laplace Noise achieves twice the signal-to-noise ratio of the matched filter for Gaussian noise. The theoretic analysis is corroborated by computer simulations
Optimal Data Rate for Reliable Packet Communications in Laplace Noise
No full textVehicular, military and industrial field wireless deployments take place in harsh environments affected by impulsive noise. This letter proposes the use of a selective automatic repeatrequest (SR-ARQ) scheme where the data transmission rate is optimized in order to minimize the mean delay. The optimizationprocedure is proposed in relation to the use of a soft-limiting detector that eliminates out-of-amplitude noise at the receivingend. The superiority of the optimized SR-ARQ
An Optimized CoMP Transmission for a Heterogeneous Network Using eICIC Approach
No full textHeterogeneous networks deployment is one of the most promising approaches to face the expected increase of the requested communication capacity. The concept is that of increasing the cells number
while reducing their size in order to provide different layers of coverage. This paper proposes a coordinated method to face the inter and intra layer interference caused by the overlapping of heterogeneous
cells. The aim is to exploit the benefits of both the enhanced InterCell Interference Coordination (eICIC) and Coordinated MultiPoint (CoMP) approaches and to limit at the same time their drawbacks by means of their optimized joint use. The idea devised here is to build an ad-hoc CoMP system on the top of a basic eICIC mechanism. The problem is the dynamic selection of the users and the cells that are
involved in CoMP operations, with the goal of minimizing the unfulfilled data rate requests. Due to the computational complexity of the optimal solution, we propose a heuristic procedure and validate its accuracy by providing a comparison with the optimal numerical solution. In particular, our results show that the proposed method outperforms other benchmark solutions in terms of unfulfilled data rate
requests and signaling overhead
Coordinated Scheduling and Beamforming Scheme for LTE-A HetNet Exploiting Direction of Arrival
No full textResource reuse among different cells in LTE-A networks will permit to increase the system capacity, but will require suitable interference mitigation techniques. Among these Coordinated scheduling and beamforming (CS/CB) is a promising solution. This paper proposes a new CS/CB scheme aiming to maximizing the mean system throughput taking into account the fairness among the cells. First the most suitable CB technique selection is analysed and a sub-optimum criterion based on the reciprocal angular distance between two concurrent users is proposed. Then a smart CS algorithm that allows to pair users with sufficient angular distance is introduced. The results show that the proposed scheme achieves performance close to the optimum CB scheme selection and the smart allocation permits to increase significantly the system throughput
Physical Layer Network Coding in Multipath Channel: Effective Precoding-Based Transmission Scheme
No full textThis paper analyzes the performance of the Physical Layer Network Coding (PLNC) approach based on Decode-and-Forward (DF) and operating in multipath fading channel. In actual channel affected by multipath fading the DF method has poor performance since the relay node cannot properly perform data decoding. In addition the decoding at the relay requires the knowledge of the channels involved in the communication with a consequent signaling overhead. In order to overcome these problems this paper proposes an Orthogonal Frequency Division Multiplex (OFDM) system where the pre-emphasis approach is considered jointly with an efficient method of sub-carrier suppression named Blind Subcarrier Suppression (BSS). Simulations results show that BSS achieves high throughput with a Bit Error Probability (BER) near to that of a classical OFDM system in multipath channel. View full abstract
Subcarriers Suppression Methods for OFDM Systems with Decode-and-Forward Network Coding
No full textThis paper deals with the performance evaluation of Decode and Forward Physical Layer Network Coding schemes under multipath fading channel propagation conditions. Physical Layer Network Coding in Two Way Relay Networks ideally allows to drastically increase the network throughput. However, under the assumption of actual channel propagation conditions, the performance quickly degrades due to high decoding error probability. With the aim of counteracting this drawback, the paper proposes a suitable approach for Orthogonal Frequency Division Multiplexing systems based on a signal preequalization technique. Furthermore, in order to lower the decoding error probability, three subcarriers suppression methods are introduced. These methods differ from each other for the performance achieved and the required amount of signaling that nodes have to exchange. An important result obtained here is that the combined use of channel inversion and subcarriers suppression allows to enhance the system reliability with a slight decrease of the throughput
AI Based Network and Radio Resource Management in 5G HetNets
No full textThe demand for pervasive wireless access and high data rate services are expected to grow significantly in the near future. In this context, the deployment of Heterogeneous Networks (HetNets) will
enable important capabilities, such as high data rates and traffic offloading, providing dedicated capacity to homes, enterprises, and urban hotspots. Despite HetNet technology will be beneficial for
future wireless systems in many ways, the massive cells diffusion has as a consequence an exponential increase of the backhaul traffic that can create congestion and collapse the backhaul
network. Virtualization of networks and radio access allows the implementation of complex and efficient decisional processes for radio and network resource optimization, but the interaction
between lower and upper layers during resource allocation decisions is still mostly unexplored. In this paper we propose an artificial intelligence based approach, with two interdependent
decisional cores exchanging information, one aware of physical layer aspects and the other controlling pure network resources. The two iterative procedures aim at jointly optimizing the distribution of
the traffic in the backhaul network and the users cell association, with the goals of minimizing the unsatisfied users data rate requests and minimizing the energy consumption reducing the number of
activated cells, respectively
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