			Home About us Contact

Transmission Bandwidth (transmission + bandwidth)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

Experiments on space diversity effect in MIMO channel transmission with maximum data rate of 1,Gbps in downlink OFDM radio access

EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2006
Hidekazu Taoka
This paper presents experimental results on the space diversity effect in MIMO multiplexing/diversity with the target data rate up to 1,Gbps using OFDM radio access based on laboratory and field experiments including realistic impairments using the implemented MIMO transceivers with the maximum of four transmitter/receiver branches. The experimental results using multipath fading simulators show that at the frequency efficiency of less than approximately 2,bits/second/Hz, MIMO diversity using the space-time block code (STBC) increases the measured throughput compared to MIMO multiplexing owing to the high transmission space diversity effect. At a higher frequency efficiency than approximately 2--3,bits/second/Hz, however, MIMO multiplexing exhibits performance superior to that of MIMO diversity since the impairments using higher data modulation and a higher channel coding rate in MIMO diversity overcomes the space diversity effect. The results also show that the receiver space diversity effect is very effective in MIMO multiplexing for maximum likelihood detection employing QR-decomposition and the M-algorithm (QRM-MLD) signal detection. Finally, we show that the real-time throughput of 500,Mbps and 1,Gbps in a 100-MHz transmission bandwidth is achieved at the average received Eb/N0 per receiver antenna of approximately 8.0 and 14.0,dB using 16QAM modulation and Turbo coding with the coding rate of 1/2 and 8/9 respectively in 4-by-4 MIMO multiplexing in a real propagation environment. Copyright © 2006 AEIT. [source]

Improving node behaviour in a QoS control environment by means of load-dependent resource redistributions in LANs,

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 4 2005
Bernd E. Wolfinger
Abstract An important means to guarantee an acceptable quality of service in networks with real-time communication requirements is the reservation of resources at connection setup time. However, such reserved resources, e.g. transmission bandwidth, may be unused as a consequence of the variations in the actual resource demands. Therefore, a more efficient resource utilization is possible if communicating stations or end-users dynamically hand over some of the free resources temporarily to the other communication partners, e.g. of a ,broadcast network'. This paper concentrates on two fundamental problems of such a demand-based sharing of resources: on the one hand, estimation of the current resource requirement on the basis of load measurements is investigated and, on the other hand, we elaborate efficient algorithms for resource sharing respecting real-time requirements. The algorithms proposed for load estimation and for resource sharing are evaluated analytically with respect to their efficiency for worst-case, average-case and realistic load scenarios. Our approach suggested for resource and traffic management allows one to achieve significantly better utilization of network resources. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Dynamic bandwidth allocation and buffer dimensioning under equal segment scheme to support video-on-demand services

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2001
Liren Zhang
Abstract This paper focuses on the optimization of network bandwidth allocation and buffer dimensioning to transport pre-stored MPEG video data from source to playback destination across ATM networks. This is one of the most important issues in the support of video-on-demand (VoD) service. This paper provides a novel scheme in the dynamic allocation of bandwidth to segments of video using ABR mode. The dynamic bandwidth allocation is based on a new concept, called playback tunnel which is obtained from the traffic characteristics of the pre-stored MPEG video trace to determine the optimum of transmission bandwidth as well as the buffer capacity to ensure that the playback buffer neither underflows nor overflows. The proposed scheme is tested with real-life MPEG video traces. The obtained results have shown its significant performance improvement in terms of the capacity of playback buffer, the start-up playback delay, the size of video segment and the network multiplexing gain. Copyright © 2001 John Wiley & Sons, Ltd. [source]

The design and fabrication of optical fiber Bragg grating filter with dual-bandpass pair by phase sampling and phase shift techniques

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2009
Li Xia
Abstract Phase sampling and phase shift techniques are introduced in a uniform fiber Bragg grating structure to achieve a multi-bandpass filter with ultranarrow transmission bandwidth. A pair of dual-bandpass transmission windows are opened at 1542.32, 1542.36, and 1542.66, 1542.71 nm, respectively. The channel spacing between the pair can be designed by the phase sampling period, as well as the wavelength spacing in the dual-bandpass can be controlled through the phase shift length. This new kind of bandpass structure can be applied in the ultranarrow filtering in multichannel, multiwavelength distributed feedback Bragg lasing, photonic generation of microwave signal etc. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 790,791, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24140 [source]