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Transmission Power (transmission + power)

Distribution by Scientific Domains

Engineering	75%

Selected Abstracts

Low complexity bit allocation algorithm for OFDM systems

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 11 2008
Changwook Lee
Abstract A bit allocation algorithm is presented for orthogonal frequency division multiplexing (OFDM) systems. The proposed algorithm is derived from the geometric progression of the additional transmission power required by the subcarriers and the arithmetic,geometric means inequality. Consequently, this algorithm has a simple procedure and low computational complexity. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Power allocation in the context of dimensioning the air-interface of third generation W-CDMA-based cellular systems

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2002
P. Demestichas
Abstract The adoption of W-CDMA as an essential component of the air-interface of third-generation cellular systems brings to the foreground the need for new planning methodologies and software tools. In this perspective, this paper addresses planning problems that are important to the dimensioning of W-CDMA-based cellular networks. The problems aim at finding the optimal feasible allocation of transmission power to the sets of uplink and downlink connections that should be supported by the system, so as to cope with a corresponding traffic load scenario. The problems are concisely defined, mathematically formulated and solved by means of two computationally efficient, novel algorithms. The solutions of the problems may be seen as operating points at which the system performance should be driven. Finally, numerical results are presented and concluding remarks are drawn. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Scheduling and power control for MAC layer design in multihop IR-UWB networks

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 1 2010
Reena Pilakkat
Recently, a number of researchers have proposed media access control (MAC) designs for ultra-wideband (UWB) networks. Among them, designs based on scheduling and power control seem to be of great promise, particularly for quality-of-service (QoS) traffic. We investigate the efficiencies of many different choices for scheduling and power allocation for QoS traffic in a multihop impulse radio (IR)-UWB network, with the objective of achieving both high spectral efficiency and low transmission power. Specifically, we compare different scheduling schemes employing a protocol interference-based contention graph as well as a physical interference-based contention graph. We propose a relative distance to determine adjacency in the protocol interference-based contention graph. Using our improved protocol interference model with graph-based scheduling, we obtained better performance than the physical interference-based approach employing link-by-link scheduling. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Antenna diversity for DVB-S2 mobile services in railway environments

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 5 2007
S. Cioni
Abstract This paper evaluates the applicability of the DVB-S2 standard in railway environments, where the most peculiar impairment is the periodic deep fading caused by power-supply arches distributed along the rail tracks. This effect induces a link loss every time the train antenna undergoes a power arch and cannot be counteracted with transmission power. Therefore, we propose and investigate the use of antenna diversity on the train. Simulation and semi-analytical results show that second-order diversity suffices to remove the packet error floor observed in the case of a single receiving antenna, thus enabling the application of DVB-S2 to this harsh environment. Copyright © 2007 John Wiley & Sons, Ltd. [source]