Abstract: The disclosure relates to a method (30) for radio bearer release performed in a base station node (2) of a communication system (5). The base station node (2) provides one or more radio bearers to a user equipment (1), and the communication system (5) comprises a serving gateway (4). The method (30) comprises: receiving (31) an error message from the serving gateway (4), the error message indicating a faulty radio bearer; awaiting (32), for a delay time, additional error messages indicating faulty radio bearers; and releasing (33) the one or more radio bearers being indicated as faulty.

Abstract: The disclosure relates to a method (30) for radio bearer release performed in a base station node (2) of a communication system (5). The base station node (2) provides one or more radio bearers to a user equipment (1), and the communication system (5) comprises a serving gateway (4). The method (30) comprises: receiving (31) an error message from the serving gateway (4), the error message indicating a faulty radio bearer; awaiting (32), for a delay time, additional error messages indicating faulty radio bearers; and releasing (33) the one or more radio bearers being indicated as faulty.

Abstract: Wavelength drift in an optical WDM system between wavelengths launched by lasers (110) and received at a demultiplexer (50) can lead to disturbance of traffic signals if not identified and rectified rapidly. It is proposed to identify wavelength drift by determining a difference in temperature of the demultiplexer (50) for each channel between an actual temperature and a temperature for optimal transmission of the channel. The mean of these temperature differences for all channels is indicative of wavelength drift, while each difference is utilised to determine whether an individual channel is drifting in wavelength and to correct the drift. Wavelength drift can be detected and corrected whether sourced at a laser (110) or due to a temperature variation at the demultiplexer (50). Measurement and control can be performed during normal operation without impeding or degrading traffic flow. Wavelength influencing parameters other than temperature can be utilized.

Abstract: An optical network comprises a bidirectional link connecting two nodes (1) through two optical fibers (3). Optical output signals from optical transmitters (7) in a node are provided to transponders (11) issuing optical signals of well-defined wavelengths to a power combiner (13), from which optical signals are forwarded to the other node on the respective fiber. The network can have protection for failures of various components. Thus, a spare transponder (21) can receive the optical output signals of an optical transmitter (7) in the case of a failure of an ordinary transponder (11). The spare transponder (21) is also connected to the combiner (13). The optical transmitters (7) and receivers (9) can be duplicated by providing spare transmitters (7?) and spare receivers (9?). Various arrangements can be used for connecting the output of a transmitter to an ordinary transponder or the spare transponder.

Abstract: An optical communication line having optical fiber amplifiers including a pump laser can be configured to suppress the transmission of optical signals by reducing the power of the pump laser. In order that the portion of the line downstream of the amplifier can be monitored for fiber breaks causing only negligible crosstalk with a parallel working line, and with the elimination of the risk of mistaking reflections from a working line for light emitted by the standby amplifier, the light emitted by the standby amplifier is modulated by a low frequency control tone. The modulated laser light causes modulation of the amplified spontaneous emission (ASE) generated in the amplifier to create a control tone. Monitoring means disposed at the end of the optical line detect this control tone and use this as the criteria for a functional connection downstream the amplifier.

Abstract: An optical fiber network of WDM type comprises two fibers which carry light signals propagating in opposite directions and which are arranged in a ring configuration. One standby link between two neighboring nodes is inactive but is made active if an active link fails. An add and drop node used in the network has band blocking filters connected in a fiber between a drop coupler and an add coupler, taking out a share of the light power in each direction to be received through bandpass filters in receivers and adding new wavelength channels produced in transmitters, respectively. Switches are used for receiving and transmitting on the wavelength channels in correct directions. The positions of the switches can be changed when the inactive link has to become one of the two active links directly connected to the node. A very efficient use of the wavelength channels in the network can then be achieved for nodes having a minimum of in-line components, and particularly, a minimum of in-line filtering components.

Abstract: The present invention relates to an optical system with an optical amplifier having at least one input and output, a control circuit for controlling the output power of the amplifier with the aid of an output process demand signal (PD) from a control means. The control circuit comprises control means, a detector block and a means for tapping off light from an input or an output of the optical amplifier to the detector block. According to the invention, at least one check signal (A) is disposed to be sent in at least one check signal channel which passes through the optical amplifier. The detector block is configured to measure the amplitude of the control signal(s).