AU5810800A

AU5810800A - Telecommunications system

Info

Publication number: AU5810800A
Application number: AU58108/00A
Authority: AU
Inventors: Eberhard Herter
Original assignee: HERTERKOM GmbH
Current assignee: HERTERKOM GmbH
Priority date: 1999-10-23
Filing date: 2000-06-03
Publication date: 2001-05-08
Also published as: CA2391897A1; DE19950918A1; WO2001031943A1; EP1232658A1; DE19950918C2

Description

Telecommunications System This invention relates to a telecommunications system for establishing, maintaining, and releasing individual calls. Various telecommunications systems are currently in operation worldwide whereby individual calls between given subscribers can be established, maintained, and released. This applies to calls between subscribers of the respective system and to calls between subscribers of the various telecommunications systems. For the purposes of the present invention, the usual division of telecommunications systems into three areas will be adopted. First, there is the central area, from which calls, including traffic between the central areas themselves, are controlled and supervised. A second area comprises the connections from the central area to the subscriber; it is commonly referred to as the subscriber loop or local loop. The third area is the area of the terminals. As far as the second area, the local loop, is concerned, two different implementations and modes of operation can be found in conventional telecommunications systems. P/pl eh2 2 In the first type of telecommunications systems ("first" from a historical point of view), the local loop consists nearly exclusively of electric waveguides. Thus, a subscriber uses for the establishment, maintenance, and release of a call a permanently assigned electrically conductive wire or cable connection to the central area. This electrically conductive connection also serves to supply power to subscriber terminal equipment. In such telecommunications systems, the local loop constitutes about 50% (fifty percent) of the value of the overall system. The usage of or the traffic carried by the local loop, however, amounts to less than 10% (ten percent) of the actual traffic capacity. The other telecommunications system that is meanwhile used worldwide is a radiocommuuications system in which the subscriber operates both a radio transmitter and a radio receiver. In this telecommunications system, which is a broadcast system in principle, complex and costly measures must be taken regarding the network structure and operation to individualize the connections between the subscribers. This is not least due to the fact that, unlike the above-described so-called fixed network, switching functions must also be situated in the subscriber terminals. As is well known, such telecommunications systems are designed as cellular systems, in which the cell size is determined by many parameters. The cell size is mainly determined by the number of subscribers in the cell area, by the number of available radio channels, and by the possible transmitting power, i.e., not by the possible transmitting power of the central transmitters of a cell, but by the possible transmitting and receiving power of the terminals, for the terminals of such a system are 3 equipped with a local power source, i.e., a battery, whose size is a significant factor influencing the total weight and the size of the terminal. A significant aspect in fixing the transmitting power are the much-discussed health hazards to the subscriber that are constituted by the radio-frequency electromagnetic waves in the immediate vicinity of the user's head during operation of the terminal. Accordingly, one advantage of such a telecommunications system with wireless local loops over a fixed-network system is that each of the available radio channels is used only for the duration of the establishment and maintenance of a call between given subscribers, so that during the remaining time, the radio channels can be assigned to other subscribers. The object of the present invention is to provide a telecommunications system which avoids the disadvantages of the first-mentioned type of telecommunications system. The invention is characterized in that connections originating from central devices and leading to spatially distributed devices provided with local identities are implemented as electrically conductive connections, that the devices provided with local identities are designed as radio transmitting and receiving devices, and that to each such radio transmitting and receiving device, subscriber terminals which are also equipped with a radio transmitting and receiving device are connectable for the duration of a call. To permit an exchange of information necessary to a given extent between the central devices and the subscriber terminals, another preferred embodiment of the invention 4 is characterized in that out of the duration of a call, the devices provided with local identities and the subscriber terminals can be interconnected via a common service channel. In another preferred embodiment of the invention, the electrically conductive connections are the corresponding lines of existing networks, and the central devices supply the devices provided with local identities with the power required. The advantages of this solution are obvious. Because of the complete coverage of the classic telephone network with its finely distributed configuration, the devices provided with local identities can be installed at virtually any private connection or even be inserted into a cable. Because of the possible large number of devices provided with local identities, these devices can be designed very favorably both from a technical point of view and in terms of cost. The existing network with its conductive connections permits perfect channel separation from the central equipment far into the local loop, and the length of the radio link to the terminal presents no problem because of the above-mentioned coverage of the classic network. Since the existing network with its lines in the local loop also provides an electric connection, the supply of power from the central devices to the devices provided with local identities is also guaranteed. The subscriber identification necessary in the .-telecommunications system according to the invention can be implemented by simply integrating this identity into the terminal. As the simplest solution for this integration, the well-known SIM card used in mobile 4 is characterized in that out of the duration of a call, the devices provided with local identities and the subscriber terminals can be interconnected via a common service channel. In another preferred embodiment of the invention, the electrically conductive connections are the corresponding lines of existing networks, and the central devices supply the devices provided with local identities with the power required. The advantages of this solution are obvious. Because of the complete coverage of the classic telephone network with its finely distributed configuration, the devices provided with local identities can be installed at virtually any private connection or even be inserted into a cable. Because of the possible large number of devices provided with local identities, these devices can be designed very favorably both from a technical point of view and in terms of cost. The existing network with its conductive connections permits perfect channel separation from the central equipment far into the local loop, and the length of the radio link to the terminal presents no problem because of the above-mentioned coverage of the classic network. Since the existing network with its lines in the local loop also provides an electric connection, the supply of power from the central devices to the devices provided with local identities is also guaranteed. The subscriber identification necessary in the .telecommunications system according to the invention can be implemented by simply integrating this identity into the terminal. As the simplest solution for this integration, the well-known SIM card used in mobile 5 communications can be employed. In a further embodiment of the invention, the power required by the subscriber terminals is supplied from a local source, particularly from a source incorporated in the terminal. For that, too, conventional solutions for the terminals of the conventional mobile radio system can be used. On the other hand, however, terminals with higher power consumption may also be fed from separate sources, for example from the public supply mains, particularly if such terminals are operated at a fired location anyhow. According to further embodiments, however, the solutions in accordance with the invention can also be used for additional tasks. In one such embodiment, the position information of the devices provided with local identities can be evaluated via the respective terminal connected to these devices. The accuracy of this position information is very high, since the distribution of the devices provided with local identities, particularly if the existing network is used, can be chosen to be very fine, so that the short (necessary) communication range permits a correspondingly accurate position determination. In a preferred embodiment of the foregoing solution in which the evaluation takes place in locating and navigation equipment of mobile services, these mobile services can implement the operation scheduling and control for their mobile units in a very simple manner. A further embodiment of the invention in which portions of the electrically conductive connections serve as antennas for the devices provided with local identities 6 and connected thereto is advantageous both in terms of the avoidable expenditure on antennas and from the point of view of an optically inconspicuous appearance of the telecommunications system in the streetscape. In yet another preferred embodiment, an increase in the capacity of each device provided with a local identity can be achieved by making the device operable in a multiplex mode. If two or more lines are available at a location, it is proposed in a further embodiment of the invention that two or more devices provided with local identities are operable at the same location using an extended identity. In still another preferred embodiment of the invention, it is possible to determines in the radio receiver of the subscriber terminal which of the devices provided with local identities is transmitting signals that are being received with sufficient field strength, and the subscriber terminal communicates the result of the determination via its radio transmitter to the central devices. This solution has two advantages. On the one hand, a desired connection can thus be established over the best possible path; on the other hand, under high traffic conditions, it can always be determined whether a path is still available for a connection, and if so, which path is available. under the same aspects, a further embodiment is .characterized in that the radio receiver of the subscriber terminal can determine which of the devices provided with local identities is transmitting signals which are being received with sufficient field strength, 7 and that the subscriber terminal transmits the result of the determination via its radio transmitter to the central devices. It should be noted that the two solutions described in the following can be used both alternatively and in combination if this is considered useful or necessary to optimize the control of the call establishment. The invention will become more apparent from the following description of an embodiment of the invention when taken in conjunction with the accompanying drawing, in which: Fig. 1 shows schematically the so-called local loop of a prior-art radiotelephone network; and Fig. 2 shows schematically the design of the local loop in accordance with the invention. Referring to Fig. 1, there is shown a cell FZ of a prior art radiotelephone network, for example a network of the GSM type. This cell rZ is illuminated by a transceiver BTS. Since certain switching functions are already performed in the cell, a controller BSC is connected with transceiver BTS. Each cell has an allocated number of channels, which are represented by a time- and frequency division multiples link. As mentioned at the beginning, the number of channels required is determined by the possible number of subscribers and their requests for .-connections, while the number of possible channels is limited by the available frequency ranges and by the maximum number of so-called time slots. Another determining factor is the above-mentioned transmitting 8 and receiving power of the terminals. To avoid interference, the frequency ranges assigned to adjacent cells are different; this means that the same frequencies can only be used in cells which are separated by a minimum distance. in one prior-art system, these distances are on the order of five times the diameter at a cell. The reference characters TE denote the subscriber terminal. Since the bearer channels of a cell are assigned to the subscribers only for the duration of a call, the occupancy is significantly greater than is possible in a fixed network. Each cell FZ is connected to the central devices ZE via a multiplex link. Unlike the mobile radio network, the fixed network, which has been in use for about one hundred years, has electric waveguides in the local loop, which connect each subscriber to the central devices ZE. Such a fixed network is assumed in the explanation of Fig. 2. As indicated in Fig. 2, n lines run from central device ZE to the local points of connection for the subscriber terminals. The lines are buried cables with many pairs of wires, aerial cables, or open-wire lines. In addition, particularly in the case of the cable solution, many unconnected pairs of wires are present, depending on connection density. While in the conventional fixed network a connected line ends in a socket permanently associated with a subscriber, to which the various terminals are then connected directly or via an in-house line, according to the present invention, a line, here Ltg 1, for example, ends in a line termination 9 device NTR 1/1. According to the invention, this line termination device NTR 1/1, which is provided, for example, in a building at a location where the cable ends, and which is connected to the appropriate pair of wires, comprises a radio transmitting and receiving device. At the central device, this line termination device is provided with an identifier identifying it and, above all, its location, and registered. If two or more pairs of wires end at the same location, this can be easily taken into acount in the identification while retaining the location identity. In addition, each line termination device NTR is assigned a given frequency. Since the lines Ltg 1 to n of an existing fixed network used for the solution according to the invention are pairs of wires that permit the flow of direct current, the conventional power supply system for the fixed network can also be used to feed the devices provided with local identities, i.e., the line termination devices, NTR 1/1 to NTR s/y. Thus, unlike the conventional fixed network, in which the socket connected to the pair of wires has the same identity as the subscriber connected thereto, the line termination device NTR has its own identification, containing information about the location of the device as the local identity of the latter. The terminals TE now contain solely the identity of the subscriber; it makes no difference whether this identity is incorporated in the terminal permanently or _ nonpermanently, for example via the well-known SIm card. In addition, the terminals TE are equipped with a local power source.

10 Accordingly, the connection between a subscriber terminal TE, which has a radio transmitting and receiving device, and the device NTR provided with a local identity is a radio link using the respective radio channel assigned to the device NTR. As is readily apparent from Fig. 2, the density of existing lines and line terminations makes it possible to keep the length of the radio links short compared with the mobile radio system shown in Fig. 1; the nearest NTR is either in the same house or in the next house. This high density of line termination devices NTR 1/1 to NTR x/y and the resulting small size of the cells with low transmitting and receiving power permit a better utilization of the available frequencies in comparison with the system sketched in Fig. 1. Using a common service channel accessible, on the one hand, to all terminals TE and, on the other hand, to all line termination devices NTR, the terminals and line termination devices can exchange all information necessary outside of an individual call, and can make this information accessible to the central devices ZE. Because of the low transmitting and receiving power required, the risk of possible injuries to health caused by radio-frequency electromagnetic waves in the vicinity ot the head is substantially smaller than is the case with a large cell radius and higher transmitting and receiving powers. Since, as in the prior-art radio system, a radio channel is assigned only for the duration of a call, other subscribers can be served during the remaining time via the same line termination device NTR and the associated

Claims

1. A telecommunications system for establishing, maintaining, and releasing individual calls, characterized in that connections originating from central devices (ZE) and leading to spatially distributed devices (UTR) provided with local identities are implemented as electrically conductive connections, that the devices (NTR) provided with local identities are designed as radio transmitting and receiving devices, and that to each such radio transmitting and receiving device (NTR), subscriber terminals (TE) which are also equipped with a radio transmitting and receiving device are connectable for the duration of a call.

2. A telecommunications system as claimed in claim 1, characterized in that out of the duration of a call, the devices (NTR) provided with local identities and the subscriber terminals can be interconnected via a common service channel.

3. A telecommunications system as claimed in claim 1, characterized in that the electrically conductive connections are the corresponding lines (Ltg) of existing networks, and that the central devices (ZE) supply the devices (NTR) provided with local identities with the power required.

4. A telecommunications system as claimed in claim 1, 14 characterized in that the subscriber terminals (TE) have the subscriber's identity incorporated therein.

5. A telecommunications system as claimed in claim 1, characterized in that the subscriber terminals (TE) are supplied with power from a local source, particularly from a source incorporated in the respective terminal.

6. A telecommunications system as claimed in claim 1, characterized in that position information of the devices (NTR) provided with local identities can be evaluated via the respective terminals (TE) connected to these devices (NTR).

7. A telecommunications system as claimed in claim 1, characterized in that the evaluation takes place in locating and navigation equipment of mobile services (taxi, emergency, guard services etc.).

8. A telecommunications system as claimed in claim 1 or 2, characterized in that portions of the electrically conductive connections (Ltg) serve as antennas for the devices (NTR) provided with local identities and connected to them.

9. A telecommunications system as claimed in claim 1, characterized in that each device (NTR) provided with a local identity is operable in a multiplex mode. 15

10. A telecommunications system as claimed in claim 1, characterized in that two or more devices (NTR) provided with local identities are operable at the same location using an extended identity.

11. A telecommunications system as claimed in claim 1, characterized in that the radio receiver of the subscriber terminal can determine which of the devices provided with local identities is transmitting signals which are being received with sufficient field strength, and that the subscriber terminal transmits the result of the determination via its radio transmitter to the central devices.

12. A telecommunications system .as claimed in claim 1, characterized in that the radio receiver of the device provided with a local identity can determine which of the subscriber terminals are transmitting signals which are being received with sufficient field strength, and that the result of the determination is transmitted over the line to the central devices.