ARRANGEMENT FOR REPEATERS IN A RADIO-BASED COMMUNICATIONS SYSTEM

Abstract: For repeaters in a radio-based communications system, there is a function for identification and initiation of the respective repeater concerned. The said function can be effected without the need for digital decoding in the respective repeater concerned.

Description: TITLE Arrangement for repeaters in a radio-based communications system. TECHNICAL FIELD The present invention relates to an arrangement for repeaters in radio-based communications systems, for example systems of the DECT limited-area mobile access type, where a function or functions for identification and initiation is or are available for each respective repeater. PRIOR ART EP 497 490 relates to a cordless tele¬ communications system which is able to configure automatically the terminals included in the system. During installation, the base units are set out at random, after which an automatic configuration can take place by means of a simple press-button procedure. Some of the units can function as repeaters for other units. During communication (via such a repeater, for example) , a transmission protocol consisting of transmission frames is used. At the start of each frame there is information for initiating the terminals with the aid of a synchronizing segment. At the start of the frame there is also the possibility of transmitting the identity of the system in order to check that the stations are communicating on the right system. Additional information which can be transmitted in the frame is information on which carrier frequency is to be used. EP 515 029 describes a communications system which uses TDM. The system consists of a master station, a number of repeaters and slave stations. The master station can communicate with any one of the slave sta¬ tions. During communication with the repeaters, a repeater number can be added to the synchronization information. US 4 230 989 shows a communications system with repeaters. The system consists of a central interrogating station and a number of remote stations. These stations can be identified by a unique address. If a first station cannot communicate directly with the central station, a second station in the vicinity can function as a repeater. A message addressed to the first station is then relayed onwards to the first station by the second station. US 5 200 955 describes a repeater which is intended to be used in a mobile radio system which employs TDMA. The repeater can identify which channels are active and can amplify these. However, the repeater cannot identify the channel or its user. DESCRIPTION OF THE INVENTION TECHNICAL PROBLEM Repeaters in radio-based communications systems can be extremely important, in many applications, for the economy and functionality of the system. An example of a powerful repeater application is the radio-based local network application called limited-area mobile access. The application involves the terminating wire connection to the subscriber being replaced by or supplemented by radio covering the area. The subscriber is offered ter¬ minal mobility within one or more limited areas. In this application, if repeaters are used, the number of base units can be reduced by a factor of 10 - 100, for which reason the cost of, among other things, wire connection of the base units falls dramatically. The potential importance of repeaters is further reinforced by the fast-growing worldwide interest within the sector. Regardless of which repeater principle is used, certain common technical problems may occur, and these must be solved if it is to be possible to use repeaters successfully. The main object of the present invention is to propose an arrangement which solves these problems. It is also important that the ideas lying behind the invention can be implemented in existing systems so that these can be used effectively and without the system capacity dropping. The invention also solves this problem. In this connection there is therefore a need to propose novel repeater principles. A further technical problem in this connection is to propose a novel signalling procedure. SOLUTION The feature which can principally be regarded as characterizing the novel arrangement is that the said functions of identification and initiation for each repeater can be effected without the need for digital decoding in the respective repeater concerned. Embodiments of the inventive concept involve identification of the operator, subscribers/users and/or functions pertaining to the system. The initiation entails initiation of repeaters, users and functions which are involved in the system at a given time. In one embodiment, each repeater is arranged to identify the operator affiliation of the base station. It is likewise indicated how the user in question identifies the operator affiliation of the repeater. In one embodiment according to the invention, the user unit can distinguish between traffic from the base station and the repeater. In addition, the base station can distinguish between traffic from the user unit coming via the repeater and coming directly. The repeater can moreover be allocated channels for the repeater/user unit communication. The repeater can also inform the base station that system errors have occurred in the repeater/the user unit. By using half time slots, full time slots and empty time slots, identification of the operator and repeater address and initiation of the unit/function in question can take place. Further characteristics are evident from the patent claims attached. ADVANTAGES As a result of what has been proposed above, repeater functions can be used in associated radio-based communications systems, a fact which has considerable economic and functional potential for current systems and for future systems using TDMA. By means of the invention, it is possible to solve important problems regarding repeaters in TDMA systems. DESCRIPTION OF THE FIGURES A presently proposed embodiment of an arrangement which has the characteristics representative of the invention will be described hereinbelow with reference to the attached drawings, in which Figure 1 shows the principle of an example of a radio-based system in the form of DECT limited-area mobile access with repeaters, Figure 2 shows, in block diagram form, a structure for identification and initiation according to the invention, and Figure 3 shows, in the form of an explanatory diagram, how time slots and their configurations are used in connection with the identification and initiation function. DETAILED DESCRIPTION Explanation of some abbreviations which appear in the text: BAS: Base Station (corresponds to Radio Fixed Part in the DECT specification) . CPP: Cordless Portable Part (the user unit) . REP: Repeater. 1. Identification and initiation relates to how the REP identifies the BAS operator affiliation. This is necessary if the REP is to repeat only BAS traffic from the desired operator. 2. The CPP identifies the REP operator affiliation, which is necessary if the CPP is not to reach the BAS via the wrong REP as regards operator affiliation. 3. The CPP distinguishes between traffic from the BAS and the REP, which is necessary for the REP principles which affect how time slots and/or time frames are used. The CPP must know which frame and time slot is to be used for uplink to the REP. 4. The BAS distinguishes between traffic from the CPP coming via the REP and coming directly, which is necessary for the REP principles which affect how time slots and/or time frames are used. The BAS must know which frame and time slot is to be used for uplink from the REP. 5. The REP is allocated channels for REP-CPP communication. Channel allocation may be necessary in order to avoid neighbouring REPs interfering by repeating the same message on the same channel to the BAS or to the CPP. 6. The REP informs the BAS that system faults have occurred in the REP/CPP. R DIN (Repeater - IDentification and INitiation) according to the invention presupposes that the radio system uses the TDMA/TDD technique. The chief example of such a radio system is DECT. Other examples are PHP (Japan) , DCT900 and Bellcore TDMA/TDD. RIDIN consists of transmission of a consecutive sequence of TDMA time slots, which can have at least two possible states: - Full time slot - Empty time slot RIDIN can additionally use the following states: - Part of time slot. This type has either the same start or endpoint as a full slot. - Carrier wave number for the time slot. RIDIN presupposes that the receiver can measure whether a time slot is full (active) or empty (no transmission) . RIDIN may also presuppose that the receiver can determine the carrier wave number. Ths receiver does not therefore need to execute a decoding of any digital information in the time slot. RIDIN is accommodated within one time frame. RIDIN should only be transmitted in a time frame which (coincidentally) does not carry any duplex traffic. In this way, the capacity of the RIDIN system does not drop. RIDIN has the structure according to Figure 1: - Start message. Unique sequence which results in the REP interpreting the time slots as RIDIN. - Operator. - Which REP or REPs is/are covered by the initiation/allocation. Initiation/allocation of, for example, frequency for the REP-CPP communication. Figure 2 shows an example of how it is possible to form RIDIN with 12 time slots (half the DECT time frame) . In this example, the carrier wave information is not used. Despite this restriction, a great deal of information can be indicated: 9 different operators, 81 different REP addresses and 27 different initiations/- allocations. RIDIN can thus be used to indicate the operator. If the REP belongs to the operator, then the REP chooses to be synchronized according to the existing frame structure. The CPP which receives communication from the BAS via the REP can decode and, among other things, determine whether the BAS (and with it the REP) belongs to the correct operator. For systems where each REP may use only certain carrier waves, RIDIN can thus be used for such carrier wave allocation. RIDIN moreover provides the possibility of some dynamics in the frequency allocation, since new allocation can take place, when required, without the REP needing manual adjustments which necessitate additional resources. RIDIN can also be used by the REP in order to send information to the BAS. In this case RIDIN has the same structure and can be used, for example, to send information on various types of REP status/system faults. In addition, a total REP system failure can be detected by the fact that a certain time between transmission of the REP status message is exceeded. RIDIN can be used so that the CPP will know that it is in a REP system. If the CPP detects a RIDIN start sequence, then the CPP will use the frame cycle which the current repeater system requires. The use of RIDIN may be appropriate in the following situations, inter alia: - Radio-based local networks which use repeaters. - The system for cordless company exchanges. - Public access. In the above situations, the CT systems DCT900 and DECT can be used in the short term. Note that it may be entirely possible to use one and the same DCT900 portable or DECT portable (CPP) in all the above applica¬ tions. Figure 3 shows a base station, BAS, and user unit, CPP, and repeater, REP, in a DECT limited-area mobile access system.

Claims: PATENT CLAIMS 1. Arrangement for repeaters in a radio-based communications system, for example the DECT limited-area mobile access system, where functions for identification and initiation are available for each decoder, characterized in that the said functions can be effected without the need for digital decoding in the respective repeater. 2. Arrangement according to Patent Claim 1, characterized in that the identification concerns the operator(s), subscribers/users, and/or functions pertaining to the system. 3. Arrangement according to Patent Claim 1 or 2, characterized in that the initiation concerns functions which are to be used in the system upon initiation. 4. Arrangement according to any one of the preceding patent claims, characterized in that each repeater is arranged to identify the operator affiliation of the base station, which is a precondition for the repeater only repeating base station traffic from the desired operator. 5. Arrangement according to any one of the preceding patent claims, characterized in that the user unit, for example a cordless portable unit, identifies the operator affiliation of the repeater, which is a precondition if the user unit is not to reach the base station via the wrong repeater as regards operator affiliation. 6. Arrangement according to any one of the preceding patent claims, characterized in that the user unit distinguishes between traffic from the base station and the repeater, which is a precondition for the repeater principles which affect how time slots and/or time frames are used, the user unit checking on which frame and time slot can be used for uplink to the repeater. 7. Arrangement according to any one of the preceding patent claims, characterized in that the base station distinguishes between traffic from the user unit coming via the repeater and coming directly, which is a precondition for the repeater principles which affect thus use of time slots and/or time frames, the base station having to know which frame and time slot is to be used for uplink to the repeater. 8. Arrangement according to any one of the preceding patent claims, characterized in that the repeater is provided with channels for repeater/user communication, channel allocation in some cases being a precondition for avoiding neighbouring repeaters interfering by repeating the same message on the same channel to the base station or the user unit. 9. Arrangement according to any one of the preceding patent claims, characterized in that the repeater informs the base station that system errors have occurred in the repeater/user unit. 10. Arrangement according to any one of the preceding patent claims, characterized in that the radio system uses the TDMA/TDD technique and consists, for example, of the DECT system, the PHP system, the DCT900 system and/or Bellcore TDMA/TDD. 11. Arrangement according to any one of the preceding patent claims, characterized in that the transmission involves transmitting a consecutive sequence of TDMA time slots which have at least two possible states, namely the states of full time slot and empty time slot, and which also use the states of part of a time slot, which has either the same starting point or endpoint as a full slot, and carrier wave numbers for the time slot. 12. Arrangement according to any one of the preceding patent claims, characterized in that the receiver measures whether a time slot is full/active or empty/no transmission, and in that the receiver determines the carrier wave number, resulting in the receiver not having to execute a decoding of any digital information in the time slot. 13. Arrangement according to any one of the preceding patent claims, characterized in that the identification and the initiation are transmitted in a time frame which coincidentally does not carry any duplex traffic, which means that the identification and initiation functions do not reduce the capacity of the system. 14. Arrangement according to any one of the preceding patent claims, characterized in that the identification and initiation function operates with a start message which represents a unique sequence and results in the repeater interpreting the time slots as identification and initiation function, operator indication, indication of which repeater or repeaters is/are covered by initiation/allocation, and indication of initiation/- allocation of, for example, frequency for the repeater/user communication. 15. Arrangement according to any one of the preceding patent claims, characterized in that the [lacuna] for forming the identification and initiation function operates with a number of time slots, for example 12 time slots, which form half a DECT time frame, and in that the carrier wave information is not used in the present case. 16. Arrangement according to any one of the preceding patent claims, characterized in that the identification and initiation function designates the operator, in that in the case where the repeater belongs to the operator in question, the repeater chooses to be synchronized according to the current frame structure, in which case the user unit which receives the communication from the base station via the repeater can decode and, among other things, determine whether the base station and with it the repeater belongs to the correct operator. 17. Arrangement according to any one of the preceding patent claims, characterized in that for systems where each repeater may use only certain carrier waves, the said identification and initiation function is used for such carrier wave allocation, the said function permitting certain dynamics in the frequency allocation, since new allocation can take place, when required, without the repeater needing manual adjustments which necessitate additional- resources. 18. Arrangement according to any one of the preceding patent claims, characterized in that the identification and initiation function is used by the repeater in order to send information to the base station, the identifica¬ tion and initiation function in this case having the same structure and being able to be used, for example, to send information on various types of repeater status/system faults, and in that a total repeater system failure can additionally be detected by the fact that a certain time between the transmission of the repeater status message is exceeded. 19. Arrangement according to any one of the preceding patent claims, characterized in that the identification and initiation function can be used in order for the user unit to recognize that it is in a repeater system, and in the case where the user unit detects an identification/initiation function start sequence, the user unit uses the frame cycle which the current repeater system requires. 20. Arrangement according to any one of the preceding patent claims, characterized in that the identification and initiation function can be used in radio-based local networks which use repeaters, systems for cordless company exchanges, and/or public access.

Inventors: OLANDERS PETER, WICKMAN JOHAN, OLANDERS, PETER, WICKMAN, JOHAN
Applicants: OLANDERS PETER, TELIA AB, WICKMAN JOHAN, OLANDERS, PETER, WICKMAN, JOHAN
Application year: 1995
Main classification: H04B7
IPC codes: H04B7, H04W16, H04W84