Modem and method for connecting modems in parallel to a network

Abstract: Known modems coupled in parallel to a coupling need a sharing apparatus, which can be avoided by providing each modem (1)(3) with a detector (12,13) for detecting upstream/downstream signals to be transceived by an other modem (1,3) coupled to said coupling in parallel. Preferably, the detector comprises a distinguisher (14,15) for distinguishing upstream signals and downstream signals, like for example two bandpass filters, one for the upstream and one for the downstream. A further filter (17), like for example a highpass filter, between coupling and detector, prevents the modem from interfering with other (possibly transceiving) modems. The modem should have an active/passive state corresponding with a lower/higher impedance, which can be realised with a hybrid.

Description: The invention relates to a modem to be coupled to a network via a coupling and comprising a detector for detecting coupling signals. Such a modem is generally known, with said network for example being a public and/or private telecommunication network, and with said coupling being for example a wired connection or a wireless coupling. Said detector detects the signals flowing via said coupling, like for example ringing signals indicating that a call is made from said network to said modem and/or dc-currents indicating that a device like for example a telephone connected in parallel to said modem is involved in a call. US 5,905,781 discloses a modem pool apparatus with a detector to detect the activity of a modem. Inactive modems are released. US 5,530,951 discloses a telephone line sharing apparatus for enabling a plurality of telecommunications devices of any type to share a plurality of single subscriber telephone lines. The known modem is disadvantageous, inter alia, due to several of these modems when connected in parallel, especially but not exclusively Digital Subscriber Line modems or DSL modems, needing such a complicated sharing apparatus. It is an object of the invention, inter alia, of providing a modem which can be connected in parallel to an other modem without needing said complicated sharing apparatus. The modem according to the invention is characterised in that said modem comprises a transceiver for transceiving upstream/downstream signals via said coupling, with said detector detecting upstream/downstream signals to be transceived by an other modem coupled to said coupling in parallel to said modem. By providing the modem according to the invention with said detector for detecting upstream/downstream signals to be transceived by said other modem coupled to said coupling in parallel to said modem according to the invention, with each modem of course comprising said transceiver for transceiving upstream/downstream signals via said coupling, the modem according to the invention has knowledge of what is going on via said coupling at any time. The invention is based on the insight, inter alia, that functions like for example processor capacity at a central location can be relocated at decentral locations, and vice versa, with especially but not exclusively Digital Subscriber Line modems or DSL modems already being provided with high processor capacities. The invention solves the problem, inter alia, of providing a modem which can be connected in parallel to an other modem without needing said complicated sharing apparatus, by letting the modem according to the invention detect upstream/downstream signals to be transceived by an other modem coupled to said coupling in parallel to said modem according to the invention. Upstream/downstream signals comprises upstream signals (for example at 150 kHz) and/or downstream signals (for example at 500 kHz). And of course, more than two modems can be connected in parallel. A first embodiment of the modem according to the invention is characterised in that said detector comprises a distinguisher for distinguishing upstream signals to be tranceived from said other modem via said coupling to said network and downstream signals to be transceived from said network via said coupling to said other modem. By providing the detector in the modem according to the invention with said distinguisher for distinguishing upstream signals and downstream signals, the modem according to the invention has all knowledge of what is going on via said coupling at any time. Said distinguisher for example comprises two bandpass filters, one for the upstream and one for the downstream. A second embodiment of the modem according to the invention is characterised in that said modem comprises a filter to be coupled to said coupling. By providing the modem according to the invention with said filter, like for example a highpass filter, during detecting, said modem according to the invention does not interfere with the other (possibly transceiving) modem. A third embodiment of the modem according to the invention is characterised in that said modem comprises a switch coupled to said detector and to said transceiver for, in response to said detecting, switching said modem in an active/passive state. By providing the modem according to the invention with said switch for switching said modem in an active/passive state, during detecting said modem will be in a passive state, and in case of no detection of present streams, the modem can be switched into an active state. A fourth embodiment of the modem according to the invention is characterised in that said modem in said active/passive state corresponds with a lower/higher impedance. Then, an active state will correspond with the coupling (as well as the other modem) noticing a lower impedance, and a passive state will correspond with the coupling (as well as the other modem) noticing a higher impedance. A fifth embodiment of the modem according to the invention is characterised in that said modem comprises a hybrid comprising a first serial circuit including a first impedance and a first switch with a first point of them to be coupled to a first wire of said coupling, and comprising a second serial circuit including a second impedance and a second switch with a first point of them to be coupled to a second wire of said coupling, and comprising a third serial circuit including third impedances located between said wires of said coupling and coupled to said first points of said first and second serial circuits, and comprising a fourth serial circuit including fourth impedances coupled to second points of said first and second serial circuits. Such a hybrid, with said switches being in a conductive state, corresponds with a lower impedance (active state), and with said switches being in a non-conductive state, corresponds with a higher impedance (passive state), whereby said detector is to be coupled to common points of said third and fourth serial circuits, and with the rest of said modem to be coupled to said second points. The invention further relates to a method for coupling a modem to a network via a coupling and comprising a step of detecting coupling signals. The method according to the invention is characterised in that said method comprises a step of detecting upstream/downstream signals via said coupling to be transceived by an other modem coupled to said coupling in parallel to said modem. A first embodiment of the method according to the invention is characterised in that said method comprises a step of distinguishing upstream signals to be tranceived from said other modem via said coupling to said network and downstream signals to be transceived from said network via said coupling to said other modem. A second embodiment of the method according to the invention is characterised in that said method comprises a step of filtering between said modem and said coupling. A third embodiment of the method according to the invention is characterised in that said method comprises a step of, in response to said detecting, switching said modem in an active/passive state. US 5,530,951 discloses a telephone line sharing apparatus for enabling a plurality of telecommunications devices of any type to share a plurality of single subscriber telephone lines. US 6,259,775 discloses a multiline modem interface circuit including a sensing circuit for identifying a status of one or more external lines. This interface circuit is operable to automatically monitor a line to determine if it's ringing, determine whether it's allowed and couple the line to the modem for potential answer. US 6,092,122 discloses a Digital Subscriber Line modem or DSL modem. None of these references discloses the modem according to the invention. The invention will be further explained more detailledly at the hand of an example shown in the drawings, whereby figure 1 discloses a first modem according to the invention comprising a detector and a tranceiver and a highpass filter, and figure 2 discloses a second modem according to the invention comprising a detector and a transceiver and a hybrid. Figure 1 discloses a first modem 1 according to the invention (like for example a Digital Subscriber Line modem or DSL modem) comprising a processor 10 and a transceiver coupled via a connection 26 to for example a pc not shown and via a connection 25 to a switch 16, which via a connection 22 is coupled to a highpass filter 17 and to bandpass filters 14 and 15. Bandpass filters 14, 15 are coupled via connections 23, 24 to detectors 12, 13. Highpass filter 17 is coupled via a connection 21 to a switch 18, which is coupled via a (wired or wireless) coupling 20 to a (public and/or private) network not shown and is coupled wiredly or wirelessly to an other modem not shown. Processor 10 is coupled via control connections to switches 16, 18, to detectors 12, 13 and to transceiver 11. The first modem 1 according to the invention comprising detectors 12, 13, transceiver 11 and highpass filter 17 functions as follows. According to a first embodiment, said other modem not shown is not involved in any communication with said network not shown (in other words being in a passive state), and said pc not shown wishes to start a communication with said network. Then, processor 10 is informed, which switches switch 18 into a conductive state and which controls detectors 12, 13 for starting detecting, with detector 12 for example detecting upstreams (at for example 150 kHz and filtered by bandpass filter 14) flowing from said other modem to said network and with detector 13 for example detecting downstreams (at for example 500 kHz and filtered by bandpass filter 15) flowing from said network to said other modem. Due to said other modem not being in an active state, detectors 12, 13 will not detect any streams exchanged between said other modem and said network, and inform processor 10. In response to this, processor 10 informs said pc to start generating data and switches switch 16 into a conductive state and controls transceiver 1 such that said data, together with set-up-information, is sent to said network and that further data originating from said network can be processed. According to a second embodiment, said other modem not shown is involved in a communication with said network not shown (in other words being in an active state), and said pc not shown wishes to start a communication with said network. Then, processor 10 is informed, which switches switch 18 into a conductive state and which controls detectors 12, 13 for starting detecting, with detector 12 for example detecting upstreams (at for example 150 kHz and filtered by bandpass filter 14) flowing from said other modem to said network and with detector 13 for example detecting downstreams (at for example 500 kHz and filtered by bandpass filter 15) flowing from said network to said other modem. Due to said other modem now being in an active state, detectors 12, 13 will detect streams exchanged between said other modem and said network, and inform processor 10. In response to this, processor 10 informs said pc that communication is now impossible and keeps switch 16 in a non-conductive state. According to a first possibility, said pc must take the initiative of trying again to start a communication with said network. Then, processor 10 will bring switch 18 into a non-conductive state, for example. According to a second possibility, said processor 10, via detectors 12, 13 keeps on monitoring coupling 20, and keeps switch 18 in said conductive state, for example. As soon as said other modem has finished its communication, processor 10 brings switch 16 into a conductive state, informs said pc and said transceiver, etc. According to a third embodiment, said pc knows that said network could start a communication with said pc via modem 1, and informs processor 10 which brings switch 18 into a conductive state (or keeps it in a conductive state) and monitors coupling 20 via detector 13, or said processor 10 knows that said network could start a communication with said pc via modem 1, and informs said pc and brings switch 18 into a conductive state (or keeps it in a conductive state) and monitors coupling 20 via detector 13 etc. In figure 1, detectors 12 and 13 and bandpass filters 14 and 15 may, partly or entirely, be located, alternatively or additionally, for example inside transceiver 11 and/or for example parallelly to high pass filter 17 and/or switch 18. Figure 2 discloses a second modem 3 according to the invention (like for example a Digital Subscriber Line modem or DSL modem) comprising a processor 30 and a transceiver 31 coupled via a connection 58 to for example a pc not shown and via a connection 55 to a second point of a first serial circuit including a first impedance 37 and a first switch 34 with a first point of them to be coupled to a first wire 50 of said coupling 50, 51 and via a connection 57 to a second point of a second serial circuit including a second impedance 38 and a second switch 35 with a first point of them to be coupled to a second wire 51 of said coupling 50, 51. A third serial circuit including third impedances 39, 40 located between said wires 50, 51 of said coupling 50, 51 is coupled to said first points of said first and second serial circuits, and a fourth serial circuit including fourth impedances 32, 33 is coupled to said second points of said first and second serial circuits. A detector 36 is located between commom points 52, 56 of said third and fourth serial circuits. Again (wired or wireless) coupling 50, 51 is coupled to a (public and/or private) network not shown and is coupled wiredly or wirelessly to an other modem not shown. Processor 30 is coupled via control connections to switches 34, 35, to detector 36 and to transceiver 31. The second modem 3 according to the invention comprising detector 36, transceiver 31 and hybrid 32, 33, 34, 35, 37, 38, 39, 40 functions as follows. According to a fourth embodiment, said other modem not shown is not involved in any communication with said network not shown (in other words being in a passive state), and said pc not shown wishes to start a communication with said network. Then, processor 30 is informed, which controls detector 36 for starting detecting, with detector 36 for example detecting upstreams (at for example 150 kHz) flowing from said other modem to said network and for example detecting downstreams (at for example 500 kHz) flowing from said network to said other modem. Due to said other modem not being in an active state, detector 36 will not detect any streams exchanged between said other modem and said network, and inform processor 30. In response to this, processor 30 informs said pc to start generating data and brings switches 34, 35 into a conductive state and controls transceiver 31 such that said data, together with set-up-information, is sent to said network and that further data originating from said network can be processed. According to a fifth embodiment, said other modem not shown is involved in a communication with said network not shown (in other words being in an active state), and said pc not shown wishes to start a communication with said network. Then, processor 30 is informed, which controls detector 36 for starting detecting, with detector 36 for example detecting upstreams (at for example 150 kHz) flowing from said other modem to said network and for example detecting downstreams (at for example 500 kHz) flowing from said network to said other modem. Due to said other modem now being in an active state, detector 36 will detect streams exchanged between said other modem and said network, and inform processor 30. In response to this, processor 30 informs said pc that communication is now impossible and keeps switches 34, 35 in a non-conductive state. According to a first possibility, said pc must take the initiative of trying again to start a communication with said network. According to a second possibility, said processor 30, via detector 36 keeps on monitoring coupling 50, 51. As soon as said other modem has finished its communication, processor 30 brings switches 34, 35 into a conductive state, informs said pc and said transceiver, etc. According to a sixth embodiment, said pc knows that said network could start a communication with said pc via modem 3, and informs processor 30 which monitors coupling 50, 51 via detector 36, or said processor 30 knows that said network could start a communication with said pc via modem 3, and informs said pc and monitors coupling 50, 51 via detector 36 etc. According to a seventh embodiment, second modem 3 in figure 2, entirely or partly and for example excluding processor 30, may correspond with transceiver 11 in figure 1, entirely or partly. Each part of each modem shown in the form of a block or not shown, can be 100% hardware, 100% software or a mixture of both. Therefore, a detector also comprises a detecting function, a distinguisher also comprises a distinguishing function, a filter also comprises a filtering function, a switch also comprises a switching function, a transceiver also comprises a transceiving function etc. Each processor will comprise a memory not shown, and in addition, each block can have a further memory not shown for efficiency purposes. Each detector can comprise for example a demodulator and/or a comparator (or have a demodulating and/or a comparing function), thereby receiving comparison values from for example the processor. Each switch can for example be a relais, a transistor etc. Each impedance can for example be a resistance or an electronical impedance to be controlled by a processor, thereby possibly making switches superfluous. The values of the impedances of said hybrid, as well as the frequency values of the filters can be chosen voluntarily, with each choise having consequences known/clear to a person skilled in the art. Each transceiver can be divided into a separate transmitter and receiver, whereby in combination with said hybrid such a receiver possibly (and dependently upon said chosen values) either is located in parallel with said transmitter or with said detector (and then possibly combined with said detector). Further parts like further impedances can be added, for example in connections 55, 57, thereby causing consequences known/clear to a person skilled in the art.

Claims: Modem (1,3) to be coupled to a network via a coupling (20,50,51) and comprising a detector (12,13,36) for detecting coupling signals, characterised in that said modem (1,3) comprises a transceiver (11,31) for transceiving signals via said coupling (20,50,51), with said detector (12,13,36) being adapted to detect signals to be exchanged between an other modem and said network, said other modem being coupled via said coupling (20,50,51) in parallel to said modem (1,3) to the network. Modem (1,3) according to claim 1, characterised in that said detector (12,13,36) comprises a distinguisher (14,15) for distinguishing upstream signals to be tranceived from said other modem via said coupling (20,50,51) to said network and downstream signals to be transceived from said network via said coupling (20,50,51) to said other modem. Modem (1,3) according to claim 1 or 2, characterised in that said modem comprises a filter (17) to be coupled to said coupling. Modem (1,3) according to claim 1, 2 or 3, characterised in that said modem (1,3) comprises a switch (16,18,34,35) coupled to said detector (12,13,36) and to said transceiver (11,31) for, in response to said detecting, switching said modem (1,3) in an active/passive state. Modem (1,3) according to claim 4, characterised in that said modem (1,3) in said active/passive state corresponds with a lower/higher impedance. Modem (1,3) according to claim 4 or 5, characterised in that said modem (1,3) comprises a hybrid comprising a first serial circuit including a first impedance (37) and a first switch (34) with a first point of them to be coupled to a first wire (50) of said coupling (50,51), and comprising a second serial circuit including a second impedance (38) and a second switch (35) with a first point of them to be coupled to a second wire (51) of said coupling (50,51), and comprising a third serial circuit including third impedances (39,40) located between said wires (50,51) of said coupling (50,51) and coupled to said first points of said first and second serial circuits, and comprising a fourth serial circuit including fourth impedances (32,33) coupled to second points of said first and second serial circuits. Method for coupling a modem to a network via a coupling and comprising a step of detecting coupling signals, characterised in that said method comprises a step of detecting signals via said coupling to be exchanged between an other modem and said network, said other modem being coupled via said coupling in parallel to said modem to the network. Method according to claim 7, characterised in that said method comprises a step of distinguishing upstream signals to be tranceived from said other modem via said coupling to said network and downstream signals to be transceived from said network via said coupling to said other modem. Method according to claim 7 or 8, characterised in that said method comprises a step of filtering between said modem and said coupling. Method according to claim 7, 8 or 9, characterised in that said method comprises a step of, in response to said detecting, switching said modem in an active/passive state.

Inventors: JEANJEAN FRANCOIS, VAN DER PUTTEN FRANK OCTAAF, JEANJEAN, FRANCOIS, VAN DER PUTTEN, FRANK OCTAAF, Jeanjean, François
Applicants: CIT ALCATEL, ALCATEL
Application year: 2001
Main classification: H04M11
IPC codes: H04M11, H04L29, H04L27