Abstract: Provided are a method and apparatus for controlling a plurality of base stations disposed along the moving path of a moving group object, including determining a frame offset for the plurality of base stations based on a first delay time generated between the moving group object and the plurality of base stations and a second delay time generated between the plurality of base stations and the base station control device, and transferring data to be transmitted to the moving group object to the plurality of base stations based on the frame offset.

Abstract: Provided are a method of receiving downlink data and a machine type communication (MTC) device using the same. The MTC device according to the present invention which has a plurality of antennas includes a reception signal processing module that receives a downlink reference signal for each antenna from a base station, estimates reception signal quality with respect to the downlink reference signal for each antenna, and selects the antenna to receive a downlink signal in accordance with the reception signal quality with respect to each antenna.

Abstract: Disclosed are a method for configuring a radio frame, an apparatus for the same, a method for a mobile terminal to acquire synchronization with a base station, and a mobile terminal for the same. A method for configuring a radio frame, according to an example embodiment of the present invention, comprises generating a first synchronization signal and arranging the first synchronization signal in a slot for synchronization signal, generating a second synchronization signal and arranging the second synchronization signal in a predetermined position from the first synchronization signal, and constructing a radio frame including the first synchronization signal and the second synchronization signal. A plurality of secondary synchronization signals include difference sequences derived from a same sequence, and constitute hopping code with a predetermined hamming distance.

Abstract: Provided are a method of receiving downlink data and a machine type communication (MTC) device using the same. The MTC device according to the present invention which has a plurality of antennas includes a reception signal processing module that receives a downlink reference signal for each antenna from a base station, estimates reception signal quality with respect to the downlink reference signal for each antenna, and selects the antenna to receive a downlink signal in accordance with the reception signal quality with respect to each antenna.

Abstract: Provided is a rate matching apparatus. The rate matching apparatus includes interleavers, dummy bit removers, a bit collector, a memory and a selector. The interleavers interleave code blocks, respectively. The dummy bit removers remove dummy bits of the interleaved code blocks, respectively. The bit collector collects code blocks with the dummy bits removed by bit units, and divides a collected data bit stream into systematic data and parity data. The memory stores the systematic data and the parity data in parallel. The selector outputs in parallel a plurality of data bits which are selected from the systematic data and parity data of the memory.

Abstract: Provided is an auto gain control method in a digital communication system. The auto gain control method checks a distribution of a signal and a distribution of a signal envelope during a regular check interval, and determines a state of a current gain value from the distribution of the signal and the distribution of the signal envelope which are obtained through the checking of the distribution. The auto gain control method controls a gain value for auto gain control according to the determined state of the current gain value.

Abstract: Provided is a rate matching apparatus. The rate matching apparatus includes interleavers, dummy bit removers, a bit collector, a memory and a selector. The interleavers interleave code blocks, respectively. The dummy bit removers remove dummy bits of the interleaved code blocks, respectively. The bit collector collects code blocks with the dummy bits removed by bit units, and divides a collected data bit stream into systematic data and parity data. The memory stores the systematic data and the parity data in parallel. The selector outputs in parallel a plurality of data bits which are selected from the systematic data and parity data of the memory.

Abstract: Provided is a method of efficiently determining a location of a terminal. The method includes receiving both of a GPS signal and a mobile communication signal. When the GPS signal is not received, a location calculated using the mobile communication signal is determined as the location of the terminal.

Abstract: Provided are a method and apparatus for derate matching a rate-matched data. The received data is deinterleaved and derate matched at a time, without using input buffers or constructing input buffers in parallel. Thus, a total process time necessary for the deinterleaving process and the derate matching process is reduced, and the use of memories such as the input buffers is minimized.

Abstract: Provided is an auto gain control method in a digital communication system. The auto gain control method checks a distribution of a signal and a distribution of a signal envelope during a regular check interval, and determines a state of a current gain value from the distribution of the signal and the distribution of the signal envelope which are obtained through the checking of the distribution. The auto gain control method controls a gain value for auto gain control according to the determined state of the current gain value.

Abstract: Provided are a method and apparatus for derate matching a rate-matched data. The received data is deinterleaved and derate matched at a time, without using input buffers or constructing input buffers in parallel. Thus, a total process time necessary for the deinterleaving process and the derate matching process is reduced, and the use of memories such as the input buffers is minimized.

Abstract: There are provided a method and system for monitoring an optical transmission line. The system for monitoring the optical transmission line includes: an OTDR (optical time-domain reflectometer) transmitting a monitoring light to an optical transmission line, measuring a reflected light or backscattered light to monitor the optical transmission line; an optical amplification unit amplifying the monitoring light transmitted on the optical transmission line by using a gain clamped optical amplifier; and a filter unit removing a component having a wavelength outside a wavelength band of the monitoring light from a backward ASE (amplified spontaneous emission) generated by the optical amplification unit. Accordingly, it is possible to extend an optical transmission line monitoring distance of the OTDR. As a result, it is possible to prevent deterioration of the performance of the OTDR because of the backward ASE.

Abstract: Provided is a hybrid optical amplifier using a gain-clamped semiconductor optical amplifier enabling Raman amplification. The hybrid optical amplifier comprises a spool of optical fiber used as transmission line in the optical communication, a GCSOA amplifying optical signal input via the optical fiber and generating a self-oscillation laser beam for gain-clamping through the gain medium, and a backward pumping Raman optical amplifier inducing Raman amplification by emitting the self-oscillation laser beam generated by the GCSOA into the optical fiber. Therefore, the Raman amplification can be obtained with a relatively simple structure using the GCSOA.

Abstract: Provided are a Raman amplifier and a Raman pumping method. A light source unit outputs a pumping light having a wavelength that periodically changes. A light intensity control unit varies a light intensity of the pumping light using the pumping light to improve the gain flatness of a Raman gain. A control unit directs the light intensity control unit to control the light intensity of the pumping light in synchronization with changes in the wavelength of the pumping light.

Abstract: A long-wavelength band (L-band) optical amplifier capable of maintaining a gain constant, thereby providing a stable optical output even when an optical power or a wavelength of a signal input thereto changes. The optical amplifier includes an amplifier which amplifies an input signal, and an amplified spontaneous emission (ASE) reflector which reflects backward ASE generated by the amplifier so that the backward ASE is fed back to the amplifier.

Abstract: A method for realizing, in a fiber amplifier with three stages of amplifiers, automatic gain control in which a constant gain is obtained when channels are varied, and automatic level control in which a constant output per channel is obtained when a light power is varied because of variations in span loss. A light power or another light power of a specific wavelength is monitored to determine when variations in these light powers take place, current values of pump laser diodes appropriate for an input is read from a lookup table, and pump laser diodes are driven. During this operation, a pump power of the first stage amplifier is constantly maintained, and those of the second or third stage amplifier are controlled.

Abstract: The present invention provides an apparatus and method for compensating for the variation of a gain spectrum attributable to the temperature variation of a fiber amplifier, and a long-wavelength band dispersion-compensating hybrid amplifier equipped with the gain spectrum compensating apparatus. The apparatus includes a DCF located between a first amplification stage and a second amplification stage to compensate for dispersion of an optical signal output from the first amplification stage and perform Raman amplification of the optical signal using input pumping light; at least one pumping light provision means for providing forward or backward pumping light to the DCF; first and second temperature detection means for detecting temperature variations of the first and second amplification stages, respectively; and control means for controlling intensity of the pumping light of the pumping light provision means according to the detected temperature variations.

Abstract: Provided are a Raman amplifier and a Raman pumping method. A light source unit outputs a pumping light having a wavelength that periodically changes. A light intensity control unit varies a light intensity of the pumping light using the pumping light to improve the gain flatness of a Raman gain. A control unit directs the light intensity control unit to control the light intensity of the pumping light in synchronization with changes in the wavelength of the pumping light.

Abstract: Optical fiber amplifier with wide input power dynamic range is employed to make a first gain block and an optical fiber pumped by Raman pump have opposite spectral gain profiles each other, thereby obtaining flat output gain profile. The optical fiber amplifier includes: a first and a second gain blocks, wherein each gain block has a gain medium and at least one optical pump; an optical fiber disposed between the first and the second gain blocks; a Raman pump for generating a pumping light; and a coupling means for coupling the pumping light to the optical fiber.

Abstract: A method for realizing, in a fiber amplifier with three stages of amplifiers, automatic gain control in which a constant gain is obtained when channels are varied, and automatic level control in which a constant output per channel is obtained when a light power is varied because of variations in span loss. A light power or another light power of a specific wavelength is monitored to determine when variations in these light powers take place, current values of pump laser diodes appropriate for an input is read from a lookup table, and pump laser diodes are driven. During this operation, a pump power of the first stage amplifier is constantly maintained, and those of the second or third stage amplifier are controlled.