Ran Y.,China Telecom
IEEE Communications Magazine | Year: 2011
This article, by analyzing the damage on the communication network caused by the Wenchuan Earthquake, and the priorities of the communication restoration construction, points out that in the future emphasis shall be laid on construction of the emergency communication capability by providing priority service functions for the public switched telephone network, and attaching importance to wireless communications. It also proposes the priorities of the postdisaster network planning and construction, as well as a study on the future-oriented disaster countermeasures of networks and technologies. An earthquake measuring 8 on the Richter scale struck Wenchuan County of Aba Prefecture of Sichuan Province at 2:28:04 pm of May 12, 2008. The terrible catastrophe posed an allround test to China in terms of disaster management, a test not only on the emergency response capability of all government departments, but also on the abilities of the whole society and ordinary citizens to deal with a catastrophe. It especially put the emergency capability and fast response capability of the communication sector, the Life Line, to a severe test. © 2006 IEEE. Source
Zhang G.,China Telecom |
De Leenheer M.,Ghent University |
Morea A.,Alcatel - Lucent |
Mukherjee B.,University of California at Davis
IEEE Communications Surveys and Tutorials | Year: 2013
Orthogonal frequency-division multiplexing (OFDM) is a modulation technology that has been widely adopted in many new and emerging broadband wireless and wireline communication systems. Due to its capability to transmit a high-speed data stream using multiple spectral-overlapped lower-speed subcarriers, OFDM technology offers superior advantages of high spectrum efficiency, robustness against inter-carrier and inter-symbol interference, adaptability to server channel conditions, etc. In recent years, there have been intensive studies on optical OFDM (O-OFDM) transmission technologies, and it is considered a promising technology for future ultra-high-speed optical transmission. Based on O-OFDM technology, a novel elastic optical network architecture with immense flexibility and scalability in spectrum allocation and data rate accommodation could be built to support diverse services and the rapid growth of Internet traffic in the future. In this paper, we present a comprehensive survey on OFDM-based elastic optical network technologies, including basic principles of OFDM, O-OFDM technologies, the architectures of OFDM-based elastic core optical networks, and related key enabling technologies. The main advantages and issues of OFDM-based elastic core optical networks that are under research are also discussed. © 1998-2012 IEEE. Source
China Telecom | Date: 2013-10-24
A multi-frequency array antenna, includes a reflective metal plate, a low-frequency radiation column element which is arranged on the reflective metal plate and operating in a first frequency band range, and a high-frequency radiation column element operating in a second frequency band range. The low-frequency radiation column element comprises several low-frequency radiation units arranged at an equal first distance in the axial direction of a first reference axis. The high-frequency radiation column element comprises several high-frequency radiation units arranged at an equal second distance in the axial direction of the first reference axis. The first distance is 2.5 times the second distance. At least one of the low-frequency radiation units is nested with one high-frequency radiation unit locationally corresponding thereto, and at least one of the low-frequency radiation units is axially located between two adjacent high-frequency radiation units close to the low-frequency radiation unit.
China Telecom | Date: 2013-04-15
A multi-antenna array for a LTE MIMO communication system is provided in an embodiment of this invention, comprising a reflection plate and a power feed network disposed on the back of the reflection plate, a plurality of power distribution plates being arranged on the back of the reflection plate for controlling power distribution for antenna radiation units in different polarization manners respectively, the plurality of power distribution plates being disposed in upper and lower layers and are located at the geometrical center of a parallel plane of the reflection plate. The embodiment of this invention may prevent the scrambled arrangement of the power feed network in a multi-antenna array adopted in a LTE MIMO communication system, simplify power feed manner of antenna radiation units in different polarization manners, reduce complexity and the rate of errors in mass production of multi-antenna arrays of LTE MIMO communication systems, and facilitate locating faults and replacing feed circuits.
China Telecom | Date: 2013-04-12
The present invention describes a RF signal control method and device that changes the gain attenuation in real time and uses the changed gain attenuation to adjust the RF input signal. The RF signal control method and device also uses determined linear filter parameters for linearity improvement on the digital signal that results from a down-conversion and analog-to-digital converter on the RF input signal. The adjusted and improved signal is output after a digital pre-distortion and power amplification operation. In comparison with existing technologies, the adjusted gain attenuation is used to make adjustment on the RF input signal and improve linearity the RF input signal such that the resulting RF signal has better quality. Thus, the current application improves the linearity effect of a digital pre-distorter and the dynamic effect of a power amplifier for the RF signal, thereby enhancing coverage of the RF output signal.