Search results for "020302 automobile design & engineering"
showing 10 items of 111 documents
Safeguarding the Ultra-dense Networks with the aid of Physical Layer Security: A review and a case study
2016
In the wake of the extensive application of the fourth generation system, investigations of new technologies have been moving ahead vigorously to embrace the next generation communications in 2020. Thereinto, the technique of ultra-dense networks (UDNs) serves as a key enabler in meeting the roaring mobile traffic demands. With the prevalence of mobile Internet services especially those involve the mobile payment, security has gained an unprecedented amount of attention and become a highlighted feature for the fifth generation. Resource allocation, one of the most significant tools on getting over the obstacle of ubiquitous interference as well as elevating the spectrum/energy efficiency, h…
Decoupled Downlink-Uplink Coverage Analysis with Interference Management for Enriched Heterogeneous Cellular Networks
2016
Heterogeneous cellular networks (HetCNets) offer a promising solution to cope with the current cellular coverage crunch. Due to the large transmit power disparity, while following maximum power received (MPR) association scheme, a larger number of users are associated with macro-cell BS (MBS) than small-cell BSs (SBSs). Therefore, an imbalance load arrangement takes place across the HetCNets. Hence, using cell range expansion-based cell association, we can balance the load across the congested MBS. However, using MPR association scheme, users’ offloading leads to two challenges: 1) macro-cell interference , in which the MBS interferes with the offloaded users, and 2) coupled downlink-uplink…
Analysis of load balancing and interference management in heterogeneous cellular networks
2017
To meet the current cellular capacity demands, proactive offloading is required in heterogeneous cellular networks (HetCNets) comprising of different tiers of base stations (BSs), e.g., small-cell BSs (sBSs) and conventional macro-cell BSs (mBSs). Each tier differs from the others in terms of BS transmit power, spatial density, and association bias. Consequently, the coverage range of each tier BSs is also different from others. Due to low transmit power, a fewer number of users are associated to an sBS as compared with mBS. Thus, inefficient utilization of small-cell resources occurs. To balance the load across the network, it is necessary to push users to the underloaded small cells from …
Optimization of vehicle-trailer connection systems
2016
The three main requirements of a vehicle-trailer connection system are: en route stability, over- or under-steering restraint, minimum off-tracking along curved path. Linking the two units by four-bar trapeziums, wider stability margins may be attained in comparison with the conventional pintle-hitch for both instability types, divergent or oscillating. The stability maps are traced applying the Hurwitz method or the direct analysis of the characteristic equation at the instability threshold. Several types of four-bar linkages may be quickly tested, with the drawbars converging towards the trailer or the towing unit. The latter configuration appears preferable in terms of self-stability and…
On the Statistical Properties of Phase Crossings and Random FM Noise in Double Rayleigh Fading Channels
2016
In this paper, we study the statistics of phase processes and random frequency modulation (FM) noise encountered in double Rayleigh fading channels. The Rayleigh processes making up the double Rayleigh channel are assumed to be independent but not necessarily identically distributed. The Doppler power spectral densities of these processes are supposed to be symmetric about the carrier frequency. Under these fading conditions, we derive first an expression for the joint probability density function (jpdf) of the phase process and its rate of change. Capitalizing on this jpdf formula, we then investigate the probability density function (pdf) and cumulative distribution function (cdf) of rand…
Secondary users selection and sparse narrow-band interference mitigation in cognitive radio networks
2018
Spectrum scarcity is a critical problem that may reduce the effectiveness of wireless technologies and services. To address this problem, different spectrum management techniques have been proposed in the literature such as overlay cognitive radio (CR) where the unlicensed users can share the same spectrum with the licensed users. The main challenges in overlay CR networks are the identification and detection of the Primary User (PU) signals in a multi-source narrow-band interference (NBI) scenario. Therefore, in this paper, we investigate the performance of an orthogonal frequency division multiplexing (OFDM) overlay CR network with Secondary Users (SUs) and subcarriers selection schemes. …
A Green Mesh Routers' Placement to Ensure Small Cells Backhauling in 5G Networks
2017
International audience; The wireless industry is preparing the fifth generation wireless systems with several requirements regarding capacity and coverage area. A promising solution to meet this challenge is a densification of the network via a large scale deployment of small cells from different sizes. The advantage here is that small cells are easy to deploy and cost-efficient compared to macro base stations. However, the challenge is to ensure a reliable backhaul links. Mesh routers backhauling is one of the candidate solutions here, since it is easy to deploy, doesn't use wired connections between locations and cost-efficient. Nevertheless, the issue is to deploy routers in the suitable…
Social Network-Based Content Delivery in Device-to-Device Underlay Cellular Networks Using Matching Theory
2017
With the popularity of social network-based services, the unprecedented growth of mobile date traffic has brought a heavy burden on the traditional cellular networks. Device-to-device (D2D) communication, as a promising solution to overcome wireless spectrum crisis, can enable fast content delivery based on user activities in social networks. In this paper, we address the content delivery problem related to optimization of peer discovery and resource allocation by combining both the social and physical layer information in D2D underlay networks. The social relationship, which is modeled as the probability of selecting similar contents and estimated by using the Bayesian nonparametric models…
Partial joint processing with efficient backhauling using particle swarm optimization
2012
In cellular communication systems with frequency reuse factor of one, user terminals (UT) at the cell-edge are prone to intercell interference. Joint processing is one of the coordinated multipoint transmission techniques proposed to mitigate this interference. In the case of centralized joint processing, the channel state information fed back by the users need to be available at the central coordination node for precoding. The precoding weights (with the user data) need to be available at the corresponding base stations to serve the UTs. These increase the backhaul traffic. In this article, partial joint processing (PJP) is considered as a general framework that allows reducing the amount …
Quasi-nash equilibria for non-convex distributed power allocation games in cognitive radios
2013
In this paper, we consider a sensing-based spectrum sharing scenario in cognitive radio networks where the overall objective is to maximize the sum-rate of each cognitive radio user by optimizing jointly both the detection operation based on sensing and the power allocation, taking into account the influence of the sensing accuracy and the interference limitation to the primary users. The resulting optimization problem for each cognitive user is non-convex, thus leading to a non-convex game, which presents a new challenge when analyzing the equilibria of this game where each cognitive user represents a player. In order to deal with the non-convexity of the game, we use a new relaxed equilib…