Alcatel N.v.

Alcatel

Alcatel Sel Aktiengesellschaft

Christiaan H Sierens

Gert Van Der Plas

Denis J Mestdagh

Peter Michel Vandenabeele

Willem J Verbiest

Werner Berger

Ingrid Zulma Van De Voorde

Geert Arthur Van Wonterghem

Ulrich Steigenberger

Kristiaan Johan Venken

Cornelis Krijntjes

Denis J Mestdeagh

Stephen Harnisch

Harry Franciscus VanHoof

The main station (MS) and possibly also the terminal stations (T1, T2, T3) of a telecommunication network is/are provided with memories wherein historical information (TT1, TT2, TT3, TT4, CT1, CT2, CT3), i.e. information with respect to log-in attempts of terminal stations (T1, T2, T3) in the past, is stored. This historical information is frequently updated and is used during a polled log-in method wherein terminals (T1, T2, T3) are polled either individually or in groups, executed for instance after a network crash or power-down, to limit the number of terminals that has to be polled by the main station (MS) so as to speed up the polled log-in procedure. The performance of the log-in of each single terminal further increases significantly if this terminal is located at a substantially fixed location in the network and if power- and delay information for transmitting upstream identification messages during log-in are also contained by the historical information.

Log-in method for a telecommunication network, main station and terminal

The method is used in a system comprising a central station (CS) coupled to each of a plurality of terminal stations (TS1-TSn), wherein the central station (CS) is enabled to transmit downstream frames (DS) to the terminal stations to allow the terminal stations to transfer upstream frames (US) to the central station in time slots assigned thereto by way of of access grant information (TEA1-TEA4) included in the downstream frames. The downstream frame (DS) is a superframe having a matrix structure with rows and columns, and a first portion and a second portion of the matrix structure is an overhead portion (S, TCB) and an information portion (ATM) respectively. The overhead portion includes the access grant information and the size of the overhead portion is flexibly adaptable. The central station and the terminal stations are adapted to send and to interpret the superframe.

Method for TDMA management, central station, terminal station and

To allocate time slots to terminal stations (T1 . . . Ti . . . Tn) for transmission of upstream burst (UB) in a network system wherein a central station (CS) is coupled to a plurality of terminal stations (T1 . . . Ti . . . Tn), the central station (CS) downstream transmits access grant information (AGI) which forms part of downstream frames (DE). Each terminal station (Ti) is equipped with a cyclic local grant counter (LGC) which generates a local grant counter value between zero and a predetermined limit, and which is synchronized with a cyclic master grant counter (MGC) included in the central station (CS). The upstream time slots are bounded by two zero crossings of the cyclic local grant counter (LGC) and a terminal station (Ti) is allowed to transfer an upstream burst (UB) in such a time slot provided that this time slot is allocated to the terminal station (Ti) via previously received access grant information (AGI).

The compensation device is used in an optical network where signals are transmitted from a main station (M) to one or a plurality of user stations (US1 to US3). It compensates for analog optical signal distortion caused by laser chirp of a laser in the main station (M) which generates said analogue optical signal and fiber dispersion of the fiber link over which the optical signal is transmitted. The device includes a distance measuring device (R) generating a result signal (MS) indicative of the distance between the main station and the user stations and which is possibly already available in the network to perform ranging when the latter network is also used to transmit digital signals from the user stations to the main station using Time Division Multiple Access. It also includes a processing circuit (PC) which in response to a given laser chirp and the result signal, provides a tuning signal (V) to tune the bias voltage of a varactor diode (VD) which is part of the compensation circuit inserted in the electrical signal path. In an optimal implementation the measuring device (R) and the processing circuit (PC) are located in the main station (M), while the varactor diode (VD) is located in each user station.

Compensation device

The system includes two transmitters (T1, T2) and two receivers (R1, R2). One transmitter (T1) may include a wavelength tunable laser, sending an FSK optical signal (OS1) which has a constant intensity. In a first receiver (R1) this FSK optical signal (OS1) is transformed into an IM signal (OS1') by an optical pass band filter. This IM signal (OS1') is then detected by a first direct detection receiver (DM). In a second direct detection receiver (R2) the FSK optical signal (OS1) is not detected, since it has constant intensity. A second transmitter (T2) includes a Fabry Perot laser or a LED with a broad linewidth, sending an IM optical signal (OS2). This IM optical signal (OS2) is detected by the second direct detection receiver (R2). It is not detected by the first direct detection receiver (DM), because it is strongly attenuated when passing through the narrow bandpass optical filter (TM) before being applied to the first direct detection receiver. This system is especially advantageous in bidirectional optical transmission systems, due to its inherent insensitivity to reflections.

Optical transmission system

The time slot management system is included in a digital time division multiple access system includes a main station MS and a plurality of substations U1/16 connected to each other via a tree network. The substations U1/16 send to the main station MS upstream information packets in time slots assigned to each of the former stations by the main station. Part of the time slots are reserved for management information and used by the substation to inform the main station about the bandwidth needed for the further transfer of the upstream information, According to this information the time slot management system allocates the time slots and informs the substations thereof. In this way a flexible and dynamic time slot allocation is provided.

Time slot management system

To determine the equalisation delay of a substation (S3), the main station (C) of a transmission system measures, during an initial coarse measurement, the time interval between the sending of a first ranging signal to the substation and the receipt of a reply signal. This reply signal has a frequency and amplitude substantially lower than the information signals sent by other substations (S1, S2) of the system to avoid interference therewith. During a subsequent fine measurement the main station measures the time interval between the sending of a second ranging signal and the receipt of a second reply signal having the same characteristics as the information signals. The other substations have to stop transmission of signals during an interval equal to the uncertainty time interval with which the equalisation delay was measured during the coarse measurement. To be able to apply this method, the receiver at the main station includes a device (A2) used to isolate the first reply signal from the information signals and to recognize (COR) them, and a processing unit (PU) to determine the equalisation delay.

Method and apparatus for determining equalization delays in a

Optical transceiver arrangement to transmit information signals (S1, . , Sn) from a transmitter arrangement (T) to a receiver arrangement (R) over an optical waveguide (L). This is achieved by modulating electrical subcarrier waveforms with these information signals (S1, . , Sn) using modulation means (M1, . , Mn), converting them to optical signals using electrical/optical convertors (E/01, . , E/01n), and by transmitting these optical signals, by means of time division multiplexing means (TDM1, . , TDMn), in different time slots if the subcarrier waveforms have the same frequency. The modulation- and time division multiplexing means are controlled by corresponding individual control modules (C1, . , Cn) under control of a central control module (CC) included in the receiver arrangement.

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Kontich, Belgium

Christiaan H Sierens