Solutions For Cellular Networks Research Articles

Location‐based distributed caching for device‐to‐device communications underlaying cellular networks

AbstractDevice‐to‐device (D2D) communications have been viewed as a promising data offloading solution in cellular networks because of the explosive growth of multimedia applications. Because of the nature of distributed device location, distributed caching becomes an important function of D2D communications. By taking advantage of the caching capacity of the device, in this work, we explore the device storage and file frequent reuse to realize distributed content dissemination, that is, storing contents in mobile devices (named helpers). Specifically, we first investigate the average and lower bound of helper amount by dividing the network into small areas where the nodes are within each other's communication radius. Then, optimal helper amount is derived based on average helper amount and network topology. Subsequently, a location‐based distributed helper selection scheme for distributed caching is proposed based on the given optimal helper amount. In particular, nodes are selected as helpers according to their locations and degrees, and contents are placed in the manner for maximizing total user utility. Extensive simulation results demonstrate the factors that affect the optimal helper amount and the total user utility. Copyright © 2015 John Wiley & Sons, Ltd.

Hierarchical Ethernet Transport Network Architecture for backhaul cellular networks

Cellular traffic has been going through major changes in recent years. With the introduction of broadband services in 3G/4G and the continuously increasing provided data rates in high-speed packet access and Long Term Evolution (LTE), a broad range of cellular applications has emerged, changing the characteristics of cellular traffic. The traditional circuit-switched voice traffic has been taken over by packet-oriented data traffic. This shift in traffic has driven operators to prefer packet-oriented network technologies over circuit-switch technology when implementing their cellular networks. The current offered technologies, including PBB-Traffic Engineering and MPLS-TP, lack important functionality required for LTE such as automation (simple management), traffic engineering, protection, Quality of Service, and scalability. We propose a scalable Hierarchical Ethernet Transport Network Architecture (HETNA), a layer 2 transport technology that addresses these issues and brings a viable solution for cellular networks. The suggested architecture can handle streaming, real-time, multicasting, and other applications. Both connection-oriented transport services and connectionless-oriented services are supported. HETNA was simulated and prototyped, showing significant improvements over regular Ethernet in terms of buffers and control messages that enable this network to function.

Analytical framework for dimensioning hierarchical WiMax–WiFi networks

Providing diverse, ubiquitous and cost-effective broadband services is a foremost challenge for the telecommunication community. Fixed WiMAX or IEEE 802.16d is one of the most promising radio access technologies, providing high performance similar to wired xDSL systems, yet superior to that of current 3G mobile technologies. Numerous deployment concepts are foreseen for WiMAX networks. They are designed to cover isolated areas, thus embodying an appealing solution for cellular networks or wireless backhaul for WiFi access. The latter concept is of interest in this paper that puts forward an analytical model based on the economical aspects to dimension hierarchical WiMax-WiFi networks. The proposed model consists in replacing a finite number of nodes by an equivalent continuum. Its key feature lies in accounting for the effect of interference as well as for the physical layer and channel characteristics in an easy and straightforward manner. On the one hand, the model takes into consideration frequency planning and scheduling aspects; and on the other hand, it provides tractable formulae of the end-user mean capacity and coverage probability in order to properly dimension the hybrid network. Last but not least, the economical facet of network planning is considered to unravel the design trade-offs between maximizing the service provider profit and satisfying the end user requirements in terms of performance.

Positioning Based on Factor Graphs

This paper covers location determination in wireless cellular networks based on time difference of arrival (TDoA) measurements in a factor graphs framework. The resulting nonlinear estimation problem of the localization process for the mobile station cannot be solved analytically. The well-known iterative Gauss-Newton method as standard solution fails to converge for certain geometric constellations and bad initial values, and thus, it is not suitable for a general solution in cellular networks. Therefore, we propose a TDoA positioning algorithm based on factor graphs. Simulation results in terms of root-mean-square errors and cumulative density functions show that this approach achieves very accurate positioning estimates by moderate computational complexity.