Mobile telephony

About: Mobile telephony is a research topic. Over the lifetime, 38008 publications have been published within this topic receiving 553646 citations.

An overview of the femtocell concept

Abstract: The femtocell concept aims to combine fixed-line broadband access with cellular telephony using the deployment of ultra-low-cost, low-power third generation (3G) base stations in the subscribers' homes or premises. It enables operators to address new markets and introduce new high-speed services and disruptive pricing strategies to capture wireline voice minutes and to grow revenues. One of the main design challenges of the femtocell is that the hierarchical architecture and manual cell planning processes used in macrocell networks do not scale to support millions of femtocells. In this paper, a user-deployed femtocell solution based on the base station router (BSR) flat Internet Protocol (IP) cellular architecture is presented that addresses these problems, and several aspects of the proposed solution are discussed. The overall concept and key requirements are presented in detail. The auto-configuration and self-optimization process from purchase by the end user to the integration into an existing macrocellular network is described. Then the theoretical performance of a co-channel femtocell deployment is analyzed and its impact on the macrocell underlay is assessed. Finally, a financial analysis of a femtocellular home base station deployment in a macrocellular network is presented. It is shown that in urban areas, the deployment of publicly accessible home base stations with slightly increased coverage can significantly reduce the operator's annual network costs (up to 70 percent in the investigated scenario) compared to a pure macrocellular network.

A statistical model of mobile-to-mobile land communication channel

Abstract: A statistical model applicable to a local area has been developed for mobile-to-mobile urban and suburban land communication channels. Using the model, the probability distributions of the received envelope and phase, spatial-time correlation function, and the power spectral density of the complex envelope have been developed.

An overview of air interface multiple access for IMT-2000/UMTS

Abstract: The basis for any air interface design is how the common transmission medium is shared between users (i.e., multiple access scheme). The underlying multiple access method for all mobile radio systems is FDMA. The performance of TDMA and CDMA has been subject to vigorous debate, without any definitive conclusions. This article gives an overview of worldwide research and standardization activities related to the multiple access schemes for third-generation mobile communications systems IMT-2000 and UMTS.

DREAM: Dynamic Resource and Task Allocation for Energy Minimization in Mobile Cloud Systems

Abstract: To cope with increasing energy consumption in mobile devices, the mobile cloud offloading has received considerable attention from its ability to offload processing tasks of mobile devices to cloud servers, and previous studies have focused on single type tasks in fixed network environments. However, real network environments are spatio-temporally varying, and typical mobile devices have not only various types of tasks, e.g., network traffic, cloud offloadable/nonoffloadable workloads but also capabilities of CPU frequency scaling and network interface selection between WiFi and cellular. In this paper, we first jointly consider the following three dynamic problems in real mobile environments: 1) cloud offloading policy, i.e., determining to use local CPU resources or cloud resources; 2) allocation of tasks to transmit through networks and to process in local CPU; and 3) CPU clock speed and network interface controls. We propose a DREAM algorithm by invoking the Lyapunov optimization and mathematically prove that it minimizes CPU and network energy for given delay constraints. Trace-driven simulation based on real measurements demonstrates that DREAM can save over 35% of total energy than existing algorithms with the same delay. We also design DREAM architecture and demonstrate the applicability of DREAM in practice.

Mobile ad hoc networks

Abstract: Ad-hoc networks are a key in the evolution of wireless networks Ad-hoc networks are typically composed of equal nodes, which communicate over wireless links without any central control Ad-hoc wireless networks inherit the traditional problems of wireless and mobile communications, such as bandwidth optimisation, power control and transmission quality enhancement In addition, the multi-hop nature and the lack of fixed infrastructure brings new research problems such as configuration advertising, discovery and maintenance, as well as ad-hoc addressing and self-routing Many different approaches and protocols have been proposed and there are even multiple standardization efforts within the Internet Engineering Task Force, as well as academic and industrial projects This chapter focuses on the state of the art in mobile ad-hoc networks It highlights some of the emerging technologies, protocols, and approaches (at different layers) for realizing network services for users on the move in areas with possibly no pre-existing communications infrastructure