Variable bandwidth communication system

Technical field

p0001The invention relates to a method for point-to-point communication in a system with several subscriber stations and a control center, in which the Center when creating a communication link determines a respective free transmission channel within a fixed predetermined system bandwidth and assigns. Furthermore, the invention relates to a device for performing the method.

State of the art

p0002For digital communication extremely powerful broadband communications systems have been created in recent times. For example, allows ISDM concept the parallel transmission of digitized voice and data, the communication system itself does not need to distinguish between the signal sources (telephone, computer). Since conventional telephone lines for such data transfer is not suitable, a new wiring must be created in the rule.

p0003In addition to these "global" communication systems, there are also local, which offer an in-house network. Typically, these systems are, however, designed to be very specific to the computer communications.

p0004Of course no broadband systems are required for basic control and Ueberwachungsaufgaben. In the electricity sector, for example, the electricity distribution network is sufficient. It is known for. Instance, perform remote action tasks with specific störunanfälligen communication systems directly via the power distribution network.

p0005Recently, attempts have been made even to insert the cable television network for the additional transfer of simple control signals.

Summary of the Invention

p0006The object of the invention is to provide a method of the aforementioned type, which is suitable for the transmission of control signals and simple for fast data communication, while the available system bandwidth utilized as efficiently as possible. Preferably should be possible with the process communication on existing broadband carriers.

p0007According to the invention, the solution consists in that the transmission channel is occasionally equipped corresponding to the connection-specific requirements with one of several different Uebertragungsbandbreiten.

p0008The basic idea, then, is that not only the transmission channels (eg. As the Uebertragungsfrequenz), but also the Uebertragungsbandbreiten be set flexibly. So a communication link is no longer "square" claim than is absolutely necessary. In the inventive manner can be operated with a system in a flexible way in an extreme case, a large number of narrowband connections and at the other extreme, a small number of broadband connections.

p0009Preferably, the central sets the Uebertragungsbandbreite firmly on request for a connection by a calling subscriber station. Ie., The calling subscriber station reports the Centre before connecting the desired size of the bandwidth. The Centre will search within the system bandwidth a free area of ​​suitable size and divide it to the requested connection. After completion of the connection of the corresponding frequency range will be released. In such a system, it is possible that a subscriber station is able to build or to operate both Narrowband and broadband connections. Of course, it is also conceivable that a subscriber station is designed to use a certain bandwidth, wherein the system of different types are connected by subscriber stations. in the latter case, the panel can already by establishing the identity of the calling subscriber station, the proper bandwidth elicit (z. B. by reading out a subscriber table).

p0010Preferably, the system bandwidth is divided into a grid of narrow band channels. If a requested Uebertragungsbandbreite which is greater than the elementary grid, a plurality of narrow band channels are temporarily grouped together and a specific connection associated en bloc. A system bandwidth of 25 MHz, for example, is divided into a 20 or 25 KHz-raster. A single narrowband channel 20-25 KHz range then just for transmission of audio signals. By grouping 4 or 5 narrow band channels may, for. Example, a 100 KHz channel be created.

p0011Preferably at least one transmission channel set as the control channel. It is used for monitoring and control of be established and ongoing connections. Over this channel, the subscriber stations move to the center and vice versa.

p0012According to a particularly preferred embodiment, the communication runs off in two separate system bandwidth, in a first system bandwidth sending the headquarters and receive the subscriber stations only and only send in a second system bandwidth to subscriber stations and receives the headquarters. In this way, a two-way communication (duplex mode) is possible, and free of problems of echo cancellation. For two subscriber stations can communicate directly with each other, a so-called transverter is provided which transmits the light emitted from a subscriber station signals in those frequency range in which receives the other subscriber station.

p0013Preferably, the central synchronizes all subscriber stations. This can be done over a plurality of control channels. Further, it is advantageous if the transmission of signals takes place with a time slot method. A subscriber station may then transmit with little effort simultaneously different signals (digitized voice signal, control signal and fast data transmission quasi) parallel.

p0014Preferably, the establishment of a connection takes place so that a first subscriber station via the control channel of the central to mediating second subscriber station and the desired bandwidth tells you that the Central determines a free transmission channel of desired bandwidth and then calls the second subscriber station. If the second subscriber station ready for reception, the desired point-to-point connection is created. After completion of the data or signal transmission informs the first subscriber station, the headquarters and the corresponding transmission channel is released for use elsewhere.

p0015If the signal transmission in two system bandwidth, ie takes place as it directionally, then transmit and receive frequencies of a two-way connection can be established in each case in accordance with the available capacity in a flexible, not a priori a given distance from each other.

p0016It is not absolutely required that a two-way connection is symmetrical. It is also quite conceivable that the bandwidth in one direction is greater than that in the other direction. This could for example be advantageous if in a direction large amounts of data need to be transmitted and the communication in the other direction is limited to Empfangsbestätigungs- and correction signals.

p0017The inventive communication method is particularly suitable for data and signal transmission via rückwärtstauglichem broadband cable network for cable TV.

p0018To perform the process subscriber stations with variably adjustable transmit and receive frequencies and variable and therefore flexible adjustable bandwidths are required. As transmission system between the subscriber stations and the headquarters an existing cable television network is used with advantage. Such networks are usually of relatively limited extent. In order to obtain a system of a greater radius, the panel can be connected to one or more Central other local cable networks (eg. As via fiber optic cable). Communication between the central different cells will not expire as a rule according to the inventive principle (since the different centers will not be attached on the same communication medium, but directly connected).

p0019Does the communication within a cell into two system bandwidth quasi from directionally, then - as already mentioned - a so-called transverter required. It is advantageously integrated in the control panel and transmits broadband signals from the reverse range (ie, from the field, sending in the subscriber stations signals) to the forward range (in which the central station transmits and the subscriber stations receive).

p0020Preferably, the subscriber station includes a device connected to the broadband cable network connecting unit and a wireless communicating with the connected input unit. The input unit is z. B. equipped with keypad and display, to receive services such as home shopping, home banking, video-on-demand and the like to complete can. Catalog pages and videos are displayed on the screen of a well known TV. For the identification of the input unit can also be equipped with a card reader.

p0021According to a particularly preferred embodiment the connection unit has a computer terminal, which is transparent for a high-speed digital data transmission. Ie., A computer may have a suitable interface with a computer connected to any other connection unit second computers exchange data without requiring the computer to "see" the intervening interfacing. In this sense, is to dispense with a protocol between the interfacing units and the computer interfaces.

p0022As output devices for image information on the broadband cable network connected anyway televisions can be used. Television and communication signals do not interfere, since the former are known to transmit in a range of well over 100 MHz and the latter according to the invention in a range of well below 100 MHz.

p0023The subscriber stations, particularly the interfacing units are advantageously designed for the simultaneous transmission of analog audio signals and digital data.

p0024From the detailed description and the totality of the claims other advantageous embodiments and feature combinations of the invention follow.

Brief Description of Drawings

p0025In the following the invention with reference to embodiments and in connection with the drawings, will be explained in more detail. Show it:<dl id="dl0001"><dt>Fig. 1</dt><dd>a schematic representation of the inventive management and assignment of frequencies and bandwidths;</dd><dt>FIG. 2</dt><dd>a schematic representation of the two-way concept with separate forward and reverse range;</dd><dt>Fig. 3</dt><dd>a schematic representation of an inventive network;</dd><dt>Fig. 4</dt><dd>a general block diagram of an inventive connection unit; </dd><dt>Fig. 5</dt><dd>a general block diagram of an inventive input unit.</dd></dl>

WAYS OF CARRYING OUT OF THE INVENTION

p0027FIG. 1 illustrates the essence of the invention in the frequency domain. A so-called reverse range 1, in which the subscriber stations send signals to the control center, to z. B. extends over a system bandwidth of 25 MHz, starting at 5 MHz. A so-called forward section 2, in which the subscriber stations respectively signals from the central office. received from other subscriber stations, also extends over a system bandwidth of z. B. 25 Hz, however, starting with z. B. 60 MHz. Forward and backward section 2 resp. 1 are therefore a clear separation. In frequency terms, far higher range a TV area 3 is located in a conventional manner. It is the standard for the transmission of television signals reserved area.

p0028Backward and forward area 1 resp. 2 each in a channel raster 4, 5 divided by z. B. 20 or 25 KHz. So there are a maximum of 1'000 - 1'250 narrowband channels. According to the invention not only narrow, but also broadband communication links are now but possible. A fixed allocation in narrowband and broadband communication links is not provided. Rather, the available capacity will be allocated case by case basis according to the respective needs.

p0029In Fig. 1, a broadband channel for example, are 10 and 11 per two narrowband channels 8.1, 8.2, and 9.1, 9.2 as well as ever. Broadband channels 10, 11 are formed by combining a plurality of narrow band channels for a particular connection. If the wideband channels 10, 11 is no longer needed (ie terminates the corresponding connection) then the corresponding frequency range is released. Because in a constantly changing way narrowband and broadband connections are created and terminated, and since the available frequency ranges are dynamically allocated, the number and placement of narrowband and wideband channels continuously changes over time.

p0030The allocation of capacity is carried out by a center, which constantly communicates via z. B. two control channels 6, 7 with the subscriber stations. About the point situated in the forward section 2 Channel 7 synchronization signals are, for example, emitted and the point situated in the reverse range 1 Channel 6, the subscriber stations can call the center if they want to connect with another subscriber station.

p0031Fig. Figure 2 illustrates the flow of information. A center 12 sends or transmits in the forward section 2 signals and data to all connected to the network subscriber stations 13.1, 13.2. Send latter and transmit signals and data in the reverse range 1 to the control panel 12. It is not only provided that the Central 12, the data received from the subscriber stations 13.1, 13.2 edited, but also that they worked transmits those in the forward range 2 ( transvertiert), so that the subscriber stations 13.1, 13.2 (at least virtually) directly communicate with each other.

p0032Fig. 3 shows a schematic representation of an inventive communication system based on a broadband cable network 15. The well-known per se, ie, includes conventional part of the plant, an antenna system 14 for the reception of television signals, which are fed via a central 12 in the (local) broadband network 15 will. There are connections for televisions 16.1, ..., 16.6 provided. The television sets 16.1, ..., 16.6 is commercial equipment.

p0033New are certain parts of the central 12 and connectable to the broadband cable network 15 subscriber stations 13.1, ..., 13.6. The latter are connected with the TV via a T-connector on the broadband cable network 15 z. B.. Of course, a subscriber station (z. B. 13.4) function without TV. Likewise, it is of course also provide terminals that are used only in a conventional manner (eg. As a TV 16.4).

p0034The control center 12 is further connected via a schematically indicated 17 remote connection with other local networks.

p0035In the following, the different ways of communication are erleutert exemplary.

Example 1:

p0036The subscriber station 13.2 would occur with the subscriber station 13.5 in connection to transfer a large amount of data (file transfer). Therefore, calls through the control channel, the center 12 and provides it with the destination address (subscriber station 13.5) and the required bandwidth (z. B. 300 KHz) known. The center 12 determines the range in which the system bandwidth is a transmission channel of the desired capacity. Can the necessary capacity at the moment not be provided or is the desired subscriber station 13.5 busy at the moment, it shall inform the subscriber station 13.2. However, if they can determine an appropriate carrier frequency, so it calls the subscriber station 13.5, indicating that the subscriber station 13.2 tries to connect to the found frequency and with the required bandwidth. If the subscriber station 13.5 ready it signals the central office 12, which then the broadband channel created the two subscriber stations 13.2 and 13.5 provides.

p0037Both subscriber stations 13.2, 13.5 provide their receiving part a on the assigned frequency and the corresponding bandwidth. Now the fast data transfer can be performed. The Office 12 is only to the extent involved in the transmission, as they substantially unchanged transmits with her Transverter the data sent in the backward area of ​​the subscriber station 13.2 in the forward region in which the subscriber station receives 13.5.

p0038If the data transfer is complete, notify the subscriber station 13.2 this is the center 12 with which are the appropriate frequency range to otherwise use free again.

p0039It should be noted that in this case always has the Centre provided a comprehensive overview (active subscriber stations, assigned frequencies, claimed frequency bands, etc.) about the current connections.

Example 2:

p0040The subscriber station 13.4 would contact a subscriber station outside the network. It reports with the number of the desired subscriber station and the desired bandwidth of the center 12, which in turn takes over the remote connection 17 with that central contact, in their effective range is the desired subscriber station. The next steps for establishing the connection run analogously to Example 1 from, but with the difference that the communication via the two mentioned centers running. Of this, however, the subscriber station 13.4 need nothing to remember. You can act and react as if the requested subscriber station in the same local network would be in the same way.

Example 3:

p0041From the station 13.5 from home shopping to be done. The subscriber station 13.5 calls the Central 12 and tells her the number of the shopping center and the bandwidth (narrowband communication) with. As to the trunk 17 12 contact the shopping center, the Center. (The shopping center can be designed in principle as a subscriber station of the local network.) The electronic catalog can be ausgetrahlt either via antenna so that it can be received through the antenna system 14, or the corresponding catalog pages can be made accessible via remote connection 17 , This shows the electronic catalog on your TV 16.5. As to the subscriber station 13.5 are received control signals (choice of items to display pages, selecting a product, confirmation of a purchase, etc.).

p0042Further uses of the inventive system are z. B. general Fernwirkungs- or remote monitoring tasks, telephone lines etc ..

p0043Fig. 4 shows a high level block diagram of an inventive connector unit 18. Over a coaxial connector unit 19, 18 is connected to the broadband cable net 15. In an upper system bandwidth of eg. 60 - 85 MHz arrive signals that are demodulated from an RF receiver 21. The demodulated signals are passed to a control and processing circuit 22nd

p0044For transmitting data and signals an RF transmitter 20 are by the control and processing circuit 22 supplied to a transmission signal in the lower system bandwidth of eg 5 - created 30 MHz and couples it via coaxial 19 in the broadband cable network..

p0045Both RF transmitter 20 and RF receiver 21 are not only tunable to any frequency within the respective system bandwidth, but also variable in their bandwidth modulators respectively. Demodulators equipped.

p0046The control and processing circuit 22 can communicate wirelessly via a transmitter 23, a receiver 24 and an antenna 25 with an input unit (see. FIG. 5) (the radio contact between the connector unit 18 and input unit can run in conventional trains and has nothing to do with the novel communication to do in the broadband cable network 15). Next, an interface 26 is provided for fast data transfer and a RF-232 interface 27th The interface 26 allows connection to a computer for fast file transfer. The RS 232 interface can eg. As are used for long-range effect tasks.

p0047The control and processing circuit 22 includes, for. Example, a transfer controller for performing data transfer, a controller and a memory for performing the inventive communication method. Hardware Moderately based the connection unit 18 to components known per se (PU circuit FM resp. FSK modulator and demodulator products, microcomputer etc). the method is realized by permanently stored programs. For this reason, an in-depth addressing the circuit excessive details unnecessary.

p0048Fig. 5 shows a high level block diagram of an input unit 28 About an antenna 29 it is in radio contact with the connector unit 18. A control and processing circuit 32 uses a transmitter circuit 30 and is served by a receiver circuit 31. About a microphone 35 whose analog signal an a / D converter 33 is digitized speech signals can be input. A D / A converter 34 followed by speaker 36 allows the voice output. Microphone 35 and speaker 36 may be used to call, in which the corresponding two-way connection is established according to the invention via the broadband cable network 15th A tone generator 37 can be excited to generate a ring tone (signaling a call). Finally, an alphanumeric input device 38 is provided according to a preferred embodiment. There home banking, home shopping is for database queries, etc..

p0049Because connector unit 18 and input unit 28 are wirelessly connected to each other, the connector unit 18 can be placed in the vicinity of the cable connection and be operated with the input unit from somewhere in the room.

p0050Preferably, the connector unit 18 also has an audio input. (Telephone connection with analog signal transmission).

p0051The inventive communication system allows transparent data transmission with z. B. 64 Kbit / s, a voice transmission at 3.1 KHz and a About averaging of data packets in the control channel. For data transmission to 9.6 kbit / s can be used in a conventional manner, the NF or RS-232 interfaces. For higher data rates can NF- and RS-232 interfaces are used as a control channel of the (transparent) data transmission.

p0052Preferred types of modulation are FM narrowband control channels and FSK for transparent high-speed transfers.

p0053The radio link between the connector unit 18 and the input unit 28 are located in the GHz range (similar to DECT and other in-house applications).

p0054The connector unit may be configured as a standalone unit or as part of a television set. You can for. B. tuner and decoder of the TV control or query and undertakes functions on a pay-TV system.

p0055By using a time slot method (TDMA = Time Division Multiple Access) can from a unit more compounds are operated in parallel (time multiplexing). The use of other multiple access methods (such., CDMA = Code Division Multiple Access, FDMA = Frequency Division Multiple Access) is not excluded. The strict separation in the frequency domain z. B. in the CDMA method is not required.

p0056By DECT or E network-related protocols between connection unit and remote control (input unit) are used to hand-held radio phones that are designed for use in e-net, be used as a handset for the connection unit, the connection unit quasi represents the base station. With a single phone number you can then make calls both at home over the cable and over the air z. B..

p0057Thus, the invention is not limited to the embodiments described. Its central feature is the flexibility and the efficiency in the use of existing resp. predetermined Uebertragungskapazitäten.