Alcatel N.v.

Alcatel Sel Aktiengesellschaft

Alcatel Lucent

Alcatel Alsthom Compagnie Generale D'electricite

Jurgen Otterbach

Rolf Heidemann

Heinz G Krimmel

Henning Bulow

Thomas Pfeiffer

Joerg Schaepperle

Rolf Rossberg

Gustav Veith

Rainer Fritschi

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.

Method of reducing a peak to average power ratio of a modulated signal

Optical amplifier device

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.MUX), from which the two electric signals (S.sub.TV, S.sub.D) are recovered.

Optical communication system for cable-television signals and for

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.

Time-division-multiplexing method and apparatus

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). The faint direct modulation leads to a constant, limited wave length alteration of the optical signal, such that Brillouin scattering is reduced, simultaneously with the avoidance of dispersion distortions.

Optical transmitter

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.

Fiber-optic amplifier with a facility for monitoring the pump power and

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.

Optical coupler and amplifier

Prior art fiber-optic amplifiers which are used in a fiber-optic link to amplify the light signals to be transmitted have the disadvantage that the semiconductor lasers employed as pump lasers are highly sensitive to feedback, so that the stability of the light-signal transmission is impaired by pump light reflected back into the pump lasers. According to the invention, the operating current for such pump lasers (4) contains a noise current, so that the pump laser emits its pump light in many modes, which makes it insensitive to feedback. To prevent the noise component of the pump light which is caused by the noise current from affecting the amplification of the light signals to be transmitted, the noise current is filtered in such a way that its spectral components have frequencies which lie above the reciprocal lifetime of that energy level of the active laser medium which causes the amplification of the light signals.

Growing community of inventors

Leonberg, Germany

Jurgen Otterbach