Abstract: The present invention relates to a method for reducing interference in the downlink direction of a cellular radio communication system comprising base stations communicating with terminals using a frame structure showing a time and frequency extension, said frame comprising a preamble portion and at least one data portion, said terminals being adapted to receive frames for which the receive power of said at least one data portion is varying in a predefined range relative to the receive preamble power of said preamble portion, According to the present invention, the method comprises the steps of: transmitting the part of said data portion destined to said terminal with a transmit power adapted to generate a first receive power (Plow) at said terminal within said range if said terminal belongs to a first group of terminals; transmitting the part of said data portion destined to said terminal with a transmit power adapted to generate a second receive power (Phigh) at said terminal within said range, said seco

Abstract: The invention relates to a multicarrier mobile device comprising a receiver (101) for receiving a first multicarrier signal being associated with a first communication cell and a second multicarrier signal being associated with a second communication cell, an extractor (103) for extracting a first signal portion from the first multicarrier signal and for extracting a second signal portion from the second multicarrier signal and a processor (105) for determining a first interference power on the first signal portion and the second interference power on the second signal portion.

Abstract: The invention relates to a method of reducing a peak to average power ratio of a signal, wherein the signal comprises data that is designated for transmission to a sector of a plurality of sectors, and wherein the method comprises the steps of selecting a first subset of radio resources from a given set of radio resources and of assigning a subset of radio resources from the remaining set of radio resource to each sector of said plurality of sectors. Each subset of radio resources is at least approximately disjoint from another subset of radio resources. The method in accordance with the invention further comprises the step of generating the signal by combining the data on the subset of radio resources that has been assigned previously to the sector and by employing said first subset of radio resources for a reduction of the peak to average power ratio. In another aspect the invention relates to a communication network component, to a computer program product and to a wireless communication system.

Abstract: The present invention relates to a method for reducing interference in the downlink direction of a cellular radio communication system comprising base stations communicating with terminals using a frame structure showing a time and frequency extension, said frame comprising a preamble portion and at least one data portion, said terminals being adapted to receive frames for which the receive power of said at least one data portion is varying in a predefined range relative to the receive preamble power of said preamble portion, According to the present invention, the method comprises the steps of: transmitting the part of said data portion destined to said terminal with a transmit power adapted to generate a first receive power (Plow) at said terminal within said range if said terminal belongs to a first group of terminals; transmitting the part of said data portion destined to said terminal with a transmit power adapted to generate a second receive power(Phigh) at said terminal within said range, said secon

Abstract: The invention relates to a multicarrier mobile device comprising a receiver (101) for receiving a first multicarrier signal being associated with a first communication cell and a second multicarrier signal being associated with a second communication cell, an extractor (103) for extracting a first signal portion from the first multicarrier signal and for extracting a second signal portion from the second multicarrier signal and a processor (105) for determining a first interference power on the first signal portion and the second interference power on the second signal portion.

Abstract: The invention relates to a method of reducing a peak to average power ratio of a signal, wherein the signal comprises data that is designated for transmission to a sector of a plurality of sectors, and wherein the method comprises the steps of selecting a first subset of radio resources from a given set of radio resources and of assigning a subset of radio resources from the remaining set of radio resource to each sector of said plurality of sectors. Each subset of radio resources is at least approximately disjoint from another subset of radio resources. The method in accordance with the invention further comprises the step of generating the signal by combining the data on the subset of radio resources that has been assigned previously to the sector and by employing said first subset of radio resources for a reduction of the peak to average power ratio. In another aspect the invention relates to a communication network component, to a computer program product and to a wireless communication system.

Abstract: A method for detecting symbol timing in an OFDMA system is described, wherein a sub-channel comprises several groups (1) of sub carriers (2) spread over the frequency band, each group (1) of sub carriers (2) comprising at least one pilot carrier (4), said method comprising the steps of: correcting the received pilot sub carriers (4) with a set of different time shifts, calculating the standard deviation of the corrected pilot sub carriers (4) for each time shift, selecting the time shift showing the minimum standard deviation, and applying said time shift to received data sub carriers (5) on said sub-channel. Furthermore a OFDMA base station to be used to execute the method mentioned above, plus a computer program product causing a computer to perform said method is described.

Abstract: A synchronization procedure for a multipoint-to-point CDMA network (2), which minimizes the influence on the information transmission. Instead of interleaving communications and synchronization signals timewise, a simultaneous emission is proposed, in which the synchronization signals are superimposed on the communications signals. The synchronization signals are coded with a special synchronization code (6), which does not correspond to the CDMA communications code of the information signals, e.g Barker code. In addition, the synchronization signals are sent at a lower amplitude compared with the communications signals. The synchronization signals are also modulated (7) prior to sending, in particular using alternating multiplication by +1 and ?1. On the receiving side (3), the synchronization signals are detected by demodulation (12; 15), correlation (13; 16) and subsequent accumulation.

Abstract: It is the object of the invention to make available a method of transferring user data packets from a terminal to a mainframe of an S-CDMA point-to-multipoint system, in which the data transfer is optimized. The method includes the steps of a repeated transmission of reference data packets coded with pilot codes for the duration of the connections between terminals and a mainframe, wherein the reference data packets contain previously known information, and the transmission of user data packets coded with communication codes include the user information to be transferred. In a preferred embodiment of the invention the user data packets are coded synchronously in time to the reference data packets, superimposed on these, and then modulated. Each terminal is allocated a pilot code, and at least one communication code.

Abstract: The invention refers to a method for preventing attacks on a network server within a call-based-services-environment, preferably a VoIP-environment. The environment comprises a network, the network server connected to the network, a number of user agents connected to the network and means for restricting access to the network server from the network. The call server comprises an attack-detection device for detecting and identifying attacks from the network on the network server. In order to allow fast and reliable protection of the network server against attacks it is suggested that characteristic parameters of the attacks identified are entered into a black-list, the content of the black-list is transmitted via a feedback-path to an attack-prevention-device for controlling the access restricting means, the attack-prevention-device inspects and analyzes traffic directed from the network to the network server and controls the access restricting means.

Abstract: A master clock signal generated at the center (1) of a bidirectional point-to-multipoint network is transmitted in the form of time stamps in an MPEG-2 data format over the downstream channel of the network to a plurality of transmitting/receiving facilities (3). Each transmitting/receiving facility (3) derives the clock signal for the upstream channel from the master clock signal and a local clock signal generated by a reference clock (12). The center (1) compares the clock signal from each transmitting/receiving facility with the master clock signal and derives from the result of this comparison digital phase correction information individual to each transmitting/receiving facility (3), which it transmits to the respective transmitting/receiving facility (3) in the MPEG-2 data stream. The respective transmitting/receiving facility (3) uses the phase correction information to control the clock signal for the upstream channel in a numerically controlled oscillator (13).

Abstract: It is the object of the invention to make available a method of transferring user data packets from a terminal to a mainframe of an S-CDMA point-to-multipoint system, in which the data transfer is optimised. The method according to the invention is comprises the steps of a repeated transmission of reference data packets coded with pilot codes for the duration of the connections between terminals and mainframe, wherein the reference data packets contain previously known information, and the transmission of user data packets coded with communication codes comprising the user information to be transferred. In a preferred embodiment of the invention the user data packets are transmitted as coded synchronously in time to the reference data packets, superimposed on these and then modulated. Each terminal is allocated a pilot code, and at least one communication code.

Abstract: The object of the invention is to provide a cellular radio system, in particular a LMDS system wherein the utilization of the transmission capacity is optimized. The cellular radio system is characterized in particular in that each cell contains a base station, that at least one cell is divided into at least two sectors, that each sector comprises one non-overlapping zone and two overlapping zones, and that each base station is suitable to allocate at least one transmission unit (time slot or orthogonal code) simultaneously to at least two different terminals located in different, non-overlapping zones of a cell.

Abstract: The object of the invention is to provide a synchronization procedure for a multipoint-to-point CDMA network (2), which minimizes the influence on the information transmission. Instead of interleaving communications and synchronization signals timewise, a simultaneous emission is proposed, in which the synchronization signals are superimposed on the communications signals. The synchronization signals are coded with a special synchronization code (6), which does not correspond to the CDMA communications code of the information signals, e.g Barker code. In addition, the synchronization signals are sent at a lower amplitude compared with the communications signals. The synchronization signals are also modulated (7) prior to sending, in particular using alternating multiplication by +1 and −1. On the receiving side (3), the synchronization signals are detected by demodulation (12; 15), correlation (13; 16) and subsequent accumulation.

Abstract: An optical amplifier device (REG) comprises a variable optical attenuator (DG), a control unit (CTRL), and an optical amplifier (EDFA). The gain of the amplifier (EDFA) and the attenuation of the attenuator (DG) are adjusted by the control unit (CTRL) based on a correlation (KOR) of the levels of the optical signals at the output of the optical amplifier (EDFA).

Abstract: In an optical communication system in which cable-television signals and subscriber-assigned tele-communication signals are transmitted over a passive optical network (4, 5) to at least one optical network termination (6), each optical network termination (6) requires two optical-to-electrical transducers. An optical network termination (6) is disclosed which requires only one optical-to-electrical transducer (24). The system has two transmitting devices (1, 2) which each transmit a respective optical signal (O.sub.TV, O.sub.D). In the second transmitting device (2), a second electric signal (S.sub.D), whose energy occupies a second frequency band (FB2), is processed in such a way that the energy is concentrated in a subband lying outside the first frequency band (FB1) of a first electric signal (S.sub.TV). The optical-to-electrical transducer (24) in the optical network termination (6) converts the received optical signals (O.sub.TV, O.sub.D) to an electric multiplex signal (E.sub.

Abstract: In known optical distribution systems, a signal intended for the subscribers is distributed from a transmitting point to all network terminations (point-to-multipoint transmission). The receivers, which are connected to a passive optical network, are adapted to a common bit rate. If a need for a higher data rate arises at a network termination, this need can only be satisfied in the prior art by converting all receivers. This is not possible without interrupting the service. Furthermore, the conversion entails great expense, since the receivers of these network terminations where the need for information is unchanged have to be converted as well. By a time-division-multiplexing method, a time-division multiplex signal is generated which has a frame whose duration is equal to one bit period (T) of a digital signal, and which is divided into k time slots (ZS). At least two time slots (ZS) are used for one digital signal, and one respective time slot (ZS) is used for each of the remaining digital signals.

Abstract: A laser (2) of an optical transmitter (1) for the transmission of an analog broadband signal for CATV in particular, can be amplitude-modulated in two different manners with an intelligence signal (N). Direct modulation can lead to an undesired additional frequency modulation. With indirect modulation by means of an optical intensity modulator (3), Brillouin scattering occurs at powers of approximately 10 mW in an optical fiber of the transmission path connected to the optical transmitter (1). Both modulations lead to distortions of the transmitted signal. In order to avoid the disadvantages of both modulations in a technically simple fashion, the carrier emitted from a laser (2) is indirectly modulated with an intelligence signal (N) and the laser (2) also faintly directly modulated with an energy-dispersing signal (V).

Abstract: In fiber-optic amplifiers, various parameters, such as the input power, are measured to obtain information on the operating condition of the transmission link and of the fiber-optic amplifier itself. In prior art fiber-optic amplifiers, a portion of the input power is coupled out for this purpose by means of a coupler (2). If low-power optical signals such as digital signals are transmitted, the coupled-out portion of the input power can only be detected with complicated and costly circuitry. In the novel fiber-optic amplifier, the pump power and input power are monitored by coupling out and evaluating the radiation resulting from amplified spontaneous emission (ASE). This provides information on the state of the input signal.

Abstract: A coupler (1) made of optical fibers is provided with a device for detecting the light that is carried in one of the fibers at the coupler output in operation. For that purpose, the coupler (1) embedded in an enclosure (2) has at the coupler output a lens body (8) enclosing the optical fiber (pigtail 6) and a detector (9) aimed at the lens body (8). With the detector, during coupler operation, lost light dissipated via the primary coating of the optical fiber is received by the lens body (8 ) and carried by the detector (9) to an electrical evaluator.