Methods and systems for superchannel power pre-emphasis may adjust power levels of selected subcarriers of the superchannel. The power pre-emphasis may be performed at a transmission stage using a laser source, a variable optical attenuator, or a wavelength selective switch. The power pre-emphasis may be performed in-line at a reconfigurable optical add-drop multiplexer node. The power pre-emphasis may be performed using feedback control based on a receiver output. The power pre-emphasis may be performed using feedforward control based on optical path computations.

A method and a device is provided driving an optical laser diode (710, 711) during operation in an optical communication network, by determining a laser transfer function (741, 742) during operation of the laser diode (710, 711) and providing a control signal (750, 749) for driving the laser diode (710, 711) according to the laser transfer function (741, 742). Further, a method for driving a first and a second optical laser diode during operation in an optical communication network is provided. Furthermore, an optical amplifier and a communication system is suggested.

A method and a device is provided driving an optical laser diode (710, 711) during operation in an optical communication network, by determining a laser transfer function (741, 742) during operation of the laser diode (710, 711) and providing a control signal (750, 749) for driving the laser diode (710, 711) according to the laser transfer function (741, 742). Further, a method for driving a first and a second optical laser diode during operation in an optical communication network is provided. Furthermore, an optical amplifier and a communication system is suggested.

The Adaptable Pulse Position Modulation (APPM) optical communication system and process facilitate wireless communications through turbid mediums including, but not limited to, smoke, airborne dust, mist, fog, clouds, water, seawater and water-to-air (air-to-water) interfaces by controlling the signal gain at the optical detector and controlling of the signal encoding to allow high data rate operation when the signal to noise ratio is high. The system also supports signal encoding redundancy to maintain good connectivity at the cost of the communication channel data rate as the signal to noise degrades.

The Adaptable Pulse Position Modulation (APPM) optical communication system and process facilitate wireless communications through turbid mediums including, but not limited to, smoke, airborne dust, mist, fog, clouds, water, seawater and water-to-air (air-to-water) interfaces by controlling the signal gain at the optical detector and controlling of the signal encoding to allow high data rate operation when the signal to noise ratio is high. The system also supports signal encoding redundancy to maintain good connectivity at the cost of the communication channel data rate as the signal to noise degrades.

A method for operating a Distributed Antenna System (DAS) includes providing a plurality of Digital Remote Units (DRUs), each configured to send and receive wireless radio signals and providing a plurality of inter-connected Digital Access Units (DAUs), each configured to communicate with at least one of the plurality of DRUs via optical signals and each being coupled to at least one sector of a base station. The method also includes providing a plurality of sensors operable to detect activity at each of the plurality of DRUs, turning off a DRU downlink signal at one of the plurality of DRUs in response to an output from one of the plurality of sensors, and turning on a DRU downlink signal at another of the plurality of DRUs in response to an output from another of the plurality of sensors.

A method for operating a Distributed Antenna System (DAS) includes providing a plurality of Digital Remote Units (DRUs), each configured to send and receive wireless radio signals and providing a plurality of inter-connected Digital Access Units (DAUs), each configured to communicate with at least one of the plurality of DRUs via optical signals and each being coupled to at least one sector of a base station. The method also includes providing a plurality of sensors operable to detect activity at each of the plurality of DRUs, turning off a DRU downlink signal at one of the plurality of DRUs in response to an output from one of the plurality of sensors, and turning on a DRU downlink signal at another of the plurality of DRUs in response to an output from another of the plurality of sensors.

A method of power control of an optical signal transmitted by a first network element. The first network element comprising a laser and a bandpass filter operating on the optical signal produced by said laser, whereas the method comprises receiving (106) information indicative of a power level of the optical signal transmitted by the first network element; and tuning (110) the laser output wavelength in response to said received information.

A method of power control of an optical signal transmitted by a first network element. The first network element comprising a laser and a bandpass filter operating on the optical signal produced by said laser, whereas the method comprises receiving (106) information indicative of a power level of the optical signal transmitted by the first network element; and tuning (110) the laser output wavelength in response to said received information.

The present application relates to a distributed antenna system, a method and an apparatus. The distributed antenna system comprises a digital-analog expansion unit and a remote cascade chain, the remote cascade chain comprising multiple remote units cascadingly connected by means of radio frequency cable, and a first remote unit of the remote cascade chain being connected to the digital-analog expansion unit by means of radio frequency cable. The digital-analog expansion unit is used to perform a baseband processing operation on a received external signal, and to perform interconversion of an analog RF signal and a digital RF signal. On this basis, the digital-analog expansion unit and the remote units use a cable connection-based daisy chain topology, which can both increase transmission bandwidth and effectively decrease transmission link costs; in addition, baseband processing being executed by the digital-analog expansion unit, and a remote unit not requiring baseband processing equipment, can effectively lower system component costs and operating power consumption. The present system is characterized by multi-mode, multi-band support and cell splitting, is easy to expand, and has low construction difficulty.