Alcatel N.v.

Henri A Verhille

Michel A Henrion

Bart J Pauwels

Michel P De Somer

Daniel Deloddere

Daniel S Hoefkens

Gustaaf A Geernaert

Eduard C Boeykens

Joannes H Spaenjers

The video server (VS) is used in a video on demand network wherein video signals are transferred over a communication network (TSY) from said video server to terminals thereof. It includes video signal memories (VM), a server control means (SCM), a broadband switch (BS) having first ports (VP1/VPY) to which the memories (VM) are coupled, second ports (CL) coupled to the communication system (TSY) and a third port (CP) to which the server control means (SCM) is coupled. The server control means (SCM) control the transfer of the video signals from the memories (VM) and through the switch (BS) and the communication system (TSY) to the terminals. The broadband switch (BS) has a set of fourth ports (CP1/CPX) to which a set of system adaptor means (SYA1/SYAX) is coupled to adapt the video signals to a format which is compatible with the communication system. The server control means (SCM) performs the transfer of video signals firstly from the video memories (VM) to the system adaptor means (SYA1/SYAX) through the switch (BS) and then from the adaptor means to the terminals via the communication system (TSY). The system adaptor means include channel memories and adaptors to perform rate and format adaption of the video signals respectively. The channel memories and the adaptors can be directly and separately coupled to the broadband switch.

Video server that adapts video signals from memory to a format

A cell resequencing system is provided for a resequencing section (RS) of a telecommunication network through which cells of communications are transmitted. The resequencing section includes cell switching networks (SN2) having inlets (I2l/I2n/I2N) coupled to inputs (S1l/S1n/S1N) and outlets (N2l/N2m/N2M). The cells are subjected to a first variable time delay. The cell resequencing system (C1l/C1n/C1N, CK1; R2l/R2m/R2M, CK2) includes latches (R2l/R2m/R2M) coupled between the outlets (N2l/N2m/N2M) and the outputs (S2l/S2m/S2M) to subject the cells to a second variable time delay chosen for each cell so the sum of the first and second variable time delay is substantially equal to a predetermined constant time value, which determines the size of the latches (R2l/R2m/R2M). The resequencing section (RS) has two inputs (S1l, S1n/S1N) each coupled to a distinct inlet (I2l/I2n/I2 N) via a distinct transmission link (TLl/TLn/TLN). The cells are subjected to at least a fixed transfer delay (TD) during their transfer from the input (S1l/S1n/S1N) to the outlet (N2l/N2m/N2M). The fixed transfer delay forms part of the first variable time delay. The minimum size of the latches (R2l/R2m/R2M) is determined by a difference between a predetermined constant time value and the fixed transfer delay (TD).

Cell resequencing system for a telecommunication network

The packet transfer control arrangement ensures that an information packet transferred from an input to an output of a packet switching network is available in correct form at that output. It includes copying means (SE11/SEmn) located at the input of the network to make copies of the packet to be transferred, routing means (HA11/HAmn; SE11/SEmn) to transfer these copies independently from each other and possibly over at least partly distinct paths from an input to an output of the network and filtering modules (F11/Fmn) to filter out one of the copies at the output of the network.

Packet transfer control arrangement and related method

A telecommunication system for transmitting cells through switching nodes (N1-3) interconnected by groups (LG12, LG23) of transmission links, each node including an asynchronous switching network (SN1-3) which comprises several switch elements. At least one of these switch elements possesses a routing group possibility whereby the cells are distributed over its outlets and so further over the different transmission links of the link group to which the switching network is connected. This distribution is performed in function of a self-routing tag which is derived from external routing data associated with the cell. At the input ports of either each or only the first switching network (SN1) of the system, the external routing data is translated in a self-routing tag which is for instance added to the header of the cell, while at the output ports of each or of only the last switching network (SN3) of the system respectively, the self-routing tag is removed from this header. Some switch elements possess a multicast possibility whereby the cells are transferred to several outlets thereof and thereby to several link groups to which the switching network is connected.

Telecommunication system

A novel packet-oriented multiple path self-routing switching network for switching asynchronous time-division multiplexed packets is characterized in that each switch unit of at least one upstream stage of the switching network includes means for defining an available state in which the downstream switch unit is available for routing packet traffic and for transmitting availability status information to upstream switch units when the downstream switch unit is in that available state, and is further characterized in that each upstream switch unit includes means for receiving availability status information for those outputs leading to a switch unit in the available state, and for prohibiting access to any output for which such availability status information is not received.

Multiple path self-routing switching network for switching asynchronous

Multiple path, self-routing switching network for switching asynchronous

An echo canceller determines the optimum value of the required digital filter coefficient from values obtained by measuring a plurality of samples of the echo signal and by measuring, for each of a predetermined number of such samples, the replica signal sample factors which, when multiplied by the filter coefficients and summed, cancel the echo signal sample. The echo signal samples as well as the factors used to determine the replica signal samples are both measured in a way that reflects the actual environment in which the echo canceller is used. To measure each of the factors of the replica signal sample corresponding to an echo signal sample, an input signal is applied to the receive path, the filter coefficient corresponding to the factor is set to a non-zero value and the other filter coefficients to zero, and the resultant replica signal sample is then measured. It is not necessary for the echo signal and replica signal measurement to be made concurrently, or from the same location.

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Brecht, Belgium

Henri A Verhille