CN1365581A - Signalling method for a mobile telephone system - Google Patents

Abstract

The invention relates to a signalling method for a GSM-mobile telephone system. Said method comprises using at least one base station and at least one subscriber station, and a first frequency channel for the transmission of signalling information between the base station and said subscriber station. At least one element of a group of values is transmitted together with the signalling information and a first partial group of said group of values is used as frequency channel numbers for allocating the frequency channels of the GSM-mobile telephone system. A second partial group of the group of values is used for the signalling of additional control functions for the subscriber station which also perform the allocation of the frequency channels of the GSM-mobile telephone system.

Description

Signaling Methods in GSM Mobile Radio System

The invention relates to a method, a base station and a subscriber station for signaling in a GSM mobile radio system.

In mobile radio systems, messages (voice, image information or other data) are transmitted via transmission channels by means of electromagnetic waves (radio interface). The transmission takes place both in the downlink direction (downlink) from the base station to the subscriber station and in the uplink direction (uplink) from the subscriber station to the base station.

In frequency duplex (Frequency Division Duplex FDD), transmission and reception are carried out in different frequency bands which are separated accordingly, while in Time Duplex (Time Division Duplex TDD), the two directions mentioned are via different time bands. gap separated.

It is known from DE 19810285.2 that methods known as frequency multiplexing (FDMA), time multiplexing (TDMA) or code multiplexing (CDMA) can be used to distinguish signal sources and thereby analyze the signal , the methods described can also be combined with each other. A more prominent example of time multiplexing (TDMA) is the above-mentioned TDD (Time Division Duplex) transmission method, in which both transmission in the uplink direction from the base station to the subscriber station and transmission from the subscriber station to the Transmission in the downlink direction of the base station.

Starting from the GSM world standard for mobile radio systems, DE 19746894 discloses switching the communication connection from the channel of GSM transmission to the channel of TD-CDMA transmission. Complex signaling is required for switching between different mobile radio systems.

The object of the present invention is to provide an improved signaling method, an improved base station and an improved subscriber station which enable interworking between existing GSM mobile radio systems and future mobile radio systems. This task is solved by a base station with the features of claim 8, a subscriber station with the features of claim 9 and a method with the features of claim 1. Preferred developments of the invention are given by the subclaims.

In the signaling method of the GSM mobile radio system, the GSM mobile radio system has at least one base station and at least one subscriber station, between which a first frequency channel can be used for transmitting signaling information. At least one element of a value group is transmitted with the signaling information, wherein a first subgroup of the value group in the form of a channel number is used to allocate a frequency channel of the GSM mobile radio system. The second subgroup of the group of values is used for signaling additional control functions for the subscriber stations beyond the frequency channel allocation of the GSM mobile radio system.

The invention not only guarantees interoperability from the GSM mobile radio system to future mobile radio systems such as UMTS (Universal Mobile Telecommunications System), but also ensures compatibility, since existing signaling possibilities in the GSM mobile radio system can Extended for handover procedures or other control functions, this also enables the transfer of current GSM mobile radio systems to future mobile radio systems. Subscriber stations of the current GSM mobile radio system use the elements of the first subgroup in the form of channel numbers to allocate channels. In contrast, subscriber stations of the current GSM mobile radio system ignore the elements of the second subgroup of the group of values.

For subscriber stations supporting both the current GSM mobile radio system and future mobile radio systems such as W-CDMA (Code Division Multiple Access) systems, so-called multi-mode subscriber stations, they can analyze the first value of the value group Signaling information of the elements in the second subgroup. Future mobile radio systems have different coding and decoding principles here. The multi-mode subscriber station can also encode and decode the system-specific signaling information of the future mobile radio system, and thus obtain the signaling information about the principle of encoding and decoding via the first or second frequency channel, and then jointly Perform analysis and implement control functions.

The elements of this value group have hitherto only been used to determine the frequency channels of the GSM mobile radio system with fixed duplex spacing. This prior function does not use elements of the second subgroup for the intended purpose, but for other control functions. Signaling determining other mobile radio systems can thus be sent very advantageously with the use of elements of the value group.

Using the method according to the invention, for example, a protocol converter between a GSM mobile radio system and a UMTS mobile radio system can be realized very simply. The elements of the second subgroup can be used to signal to the subscriber stations that a switchover to the UMTS mobile radio system is possible and at the same time initiate a protocol switchover, ie a conversion of the protocol of the GSM mobile radio system to the protocol of the UMTS mobile radio system.

For future wireless systems, some elements within the second subgroup of said value group can be defined as "still free", so that the great flexibility and transferability achieved by the present invention will not be restricted for future systems as well. Alternatively, the value group described can also be expanded for the GSM mobile radio system in order to achieve sufficient flexibility.

The interpretation of system-specific signaling information can be controlled via elements in the second subgroup of the value group. Thus, for example, the class or priority of handover procedures between different mobile radio systems can be controlled via elements of this second subgroup, thereby preventing a system from being overloaded. Elements in the second subgroup may describe a control function, but expressed with different parameters.

Elements of said second subgroup may also advantageously be used for further signaling of control functions. If an image needs to be transmitted, for example, to the above-mentioned subscriber station during a communication, such as during a call on an existing GSM connection, elements in the second subgroup of the value group can be used in the W-CDMA system to give the above-mentioned The subscriber station sends signaling to transmit the image. Services requiring higher data rates can be transmitted separately without interrupting the communication in the GSM mobile radio system or switching the entire communication to the W-CDMA system described.

In order to assign the channel number to the channel of the GSM mobile wireless system, GSM 05.05 version 6.3.0 issued in 1997 once disclosed that the channel number (absolute wireless channel number ARFCN) specifies the channel for the downlink direction and the uplink direction respectively. Channel numbers 0-124 and 975-1023 are specified for E-GSM 900 (extended GSM 900), and channel numbers 512-885 are specified for DCS 1800 (GSM1800).

The value group 0-1023 is defined for the current GSM mobile radio system. If other frequencies and other frequency channels of the GSM mobile radio system are assigned to the first subgroup in the form of channel numbers, this limited resource of channel numbers will be used up very quickly. Provided that another value group is defined by introducing another GSM mobile radio system, the present invention can make use of the signaling sent by the elements in the second subgroup of the value group of the present GSM mobile radio system and by the other value group The signaling sent by the elements together realizes the control function. The frequency channel of the further GSM mobile radio system can be determined by using elements of the second subgroup of the value group of the present GSM mobile radio system together with the channel number of the further value group.

A subscriber station capable of establishing a communication link in both GSM mobile radio systems can switch from one system to the other GSM mobile radio system. In this case, the elements of the second subgroup act as indicators, which can indicate further signaling information. In this case, the information can be transmitted on the first channel or on the second channel. The non-uniform radio traffic of the two GSM mobile radio systems can thus be equalized according to the invention.

It is particularly preferred that at least one element of the second subgroup transmits a signaling that can switch the communication connection between the subscriber station and a base station of another mobile radio system. Another mobile radio system here is the TD-CDMA system, which can transmit with much higher data rates than the current GSM mobile radio system. If the GSM mobile radio system is overloaded or the radio connection to the base station goes bad, elements of the second subgroup can switch the communication connection to the base station of the TD-CDMA system for the subscriber stations according to the invention. Another element can realize, for example, the handover of the communication connection to a base station of the W-CDMA system.

This signaling information can be used, for example, to control the subscriber station in such a way that it can request additional information about neighboring cells and systems in the form of an intelligent subscriber station and can automatically make decisions regarding the handover procedure.

In a preferred development of the invention, the elements of the second subgroup transmitted in the first frequency channel and the system-specific elements for triggering the control function additionally transmitted in the second frequency channel are evaluated jointly. signaling information. In this case, the system-specific signaling information transmitted by means of the second frequency channel contains, for example, the frequency channel and/or the chip sequence of the CDMA system for the base station located in the CDMA system and can be used both for the GSM mobile radio system and for the CDMA system. A mobile radio system establishes communication links between communicating subscriber stations. During the communication connection to the GSM mobile radio system, said subscriber station has obtained information about neighboring cells and systems by means of elements of the second subgroup and system-specific signaling information of the CDMA system, and assigned the associated base station Stored in a list as possible choices for the switching process.

In this case, the analysis of system-specific signaling information is not restricted to one channel. The system-specific signaling information can be transmitted via the second frequency channel, so that each mobile radio system which can be received by the subscriber station evaluates the system-specific signaling information. In this case, the system-specific signaling information is received or evaluated simultaneously or independently of the elements in the second subgroup of the value group.

Particularly preferably, the control function described is used to define the switching times between time slots in the upward direction (uplink) and in the downward direction (downlink) of a time-duplex mobile radio system. The control function of the switching times between time slots in the uplink direction (uplink) and downlink direction (downlink) of a time-duplex mobile radio system is unknown in current GSM mobile radio systems. According to the invention, subscriber stations capable of establishing communication both to the GSM mobile radio system and to a time-duplex mobile radio system such as the TD-CDMA mobile radio system are able to analyze said Signaling information, and handover to time-duplex mobile radio systems, for example, in the event of a large asymmetry in the data rate between downlink and uplink.

In order to be able to distinguish as well as possible the switching times between the time slots in the upward direction (uplink) and the downward direction (downlink), small time intervals are necessary, which often cannot be transmitted by a single value group. Time interval signaling. The system-specific signaling information can realize the transmission of binary information, and the binary information can use separate signaling to better define the switching time point without affecting most transmission channels.

In a preferred development of the invention, in addition to the second subgroup of the value group used for signaling transmitted in the first frequency band, the second frequency band is also used in the upstream direction (uplink) System-specific signaling information for a frequency duplex mobile radio system is transmitted in frequency duplex intervals in the downlink and downlink directions. In this case, the frequency duplex interval can be signaled, for example, by means of a specific duplex number. Road) frequency duplex spacing. In the case of GSM mobile radio systems, only fixed frequency duplex spacings have hitherto been known. In contrast, the varying duplex spacing cannot be determined using the channel numbers in the first subgroup of the hitherto value group.

It is therefore possible to maintain a variable frequency duplex spacing with the present invention and to control the uplink (uplink) and downlink (downlink) directions separately for different services in order to make the transmission as good as possible with the data required by the protocol rate matches.

The invention will be described in detail below with the aid of exemplary embodiments and with reference to the drawings. in:

Fig. 1 shows the channel number of the numerical value group and the first subgroup of this numerical value group in the existing GSM mobile radio system,

Figure 2 shows the arrangement of interworking capabilities between the GSM mobile radio system and the future mobile radio system.

FIG. 1 shows the value group ARFCN which contains, as a first subgroup, the channel numbers for allocating frequency channels of the existing GSM mobile radio system. Here channel numbers 0-124GSM, 975-1023EGSM (extended GSM) and 512-885DCS (GSM1800) are included in the first subgroup. The unoccupied second subgroup N=130-250 can be used to send additional control function signaling for the subscriber station. Other possibilities for the second subgroup are elements 250-512 and 885-975. This refers to control functions beyond the channel allocation of the GSM mobile radio system. That is to say, with the elements of the second subgroup, the channels are not directly used, as hitherto, by means of assignment of channel numbers, but rather they are not used as intended in the form of additional control functions. Elements in the second subgroup N can then initiate a handover to the UMTS mobile radio system, for example.

An arrangement for a future mobile radio system is shown in FIG. 2 . In this case, the subscriber station MS can be both a mobile station and a static wireless client. The subscriber station MS maintains communication with the base station BS via the frequency channel F. The base station BS is connected to the telephone network PSTN via a network NW, for example, or to the Internet via a gateway.

In this embodiment both the subscriber station MS and the base station BS contain receiving and transmitting means for GSM and CDMA. As shown in FIG. 2, a subscriber station (here a static subscriber station) may also only include a receiving and transmitting device for GSM. The receiving and transmitting devices for GSM and CDMA can be implemented on the base station side in one base station BS or optionally in separate base stations BS, so that in the latter case a base station BS only supports the GSM mobile radio system , while another base station BS only supports CDMA system.

There is a communication between the subscriber station MS and the base station BS via the first frequency channel F of the GSM mobile radio system. The Internet signals via the network NW to the base station BS that a moving image transmission to the subscriber station MS is required. The control device ST of the base station BS for sending the additional control function signaling through the second subgroup of the value group - already described in Fig. 1 - sends the elements of the second subgroup in the form of signaling information, such as 140 to the subscriber station MS. The subscriber station MS analyzes the signaling information by means of the second analysis means AE - in this embodiment identical to the first analysis means for the first subgroup element - and requests the system-specific information of the CDMA system via the second frequency channel signaling information. If communication is established with the CDMA system, moving images are transmitted.

Claims (9)

1. Signaling method in a GSM mobile radio system having at least one base station (BS) and at least one subscriber station (MS), wherein between said base station (BS) and subscriber station (MS) may use a first frequency channel (F) to transmit signaling information with which at least one element of a group of values (ARFCN) is transmitted and the first subgroup of said group of values is identified in the form of a channel number frequency channels for allocating said GSM mobile radio system, It is characterized by: A second subgroup (N) of the value group (ARFCN) is used for signaling additional control functions for the subscriber station (MS) beyond the frequency channel allocation of the GSM mobile radio system. 2. The method of claim 1, wherein: Signaling is sent by at least one element of the second subgroup (N) enabling switching of a communication connection between the subscriber station (MS) and a base station (BS) of another mobile radio system. 3. The method of claim 1, wherein: Handover of the communication connection of the subscriber station (MS) to a base station (BS) in another mobile radio system is initiated by at least one element of the second subgroup (N). 4. The method as claimed in one of the preceding claims, characterized in that: The elements of the second subgroup (N) transmitted in the first frequency channel (F) and additionally system-specific signaling information transmitted in the second frequency channel for triggering the control function are jointly evaluated. 5. The method according to claim 1 or 4, characterized in that: The switching times between time slots in the upward direction (uplink) and in the downward direction (downlink) of a time-duplex mobile radio system are defined with the described control functions. 6. The method according to claim 1 or 4, characterized in that: The frequency duplex spacing in the uplink direction (uplink) and in the downlink direction (downlink) of a frequency duplex mobile radio system is specified with the described control functions. 7. The method according to claim 1 or 4, characterized in that: The corresponding frequency channels in the upward direction (uplink) and in the downward direction (downlink) of a frequency duplex mobile radio system are specified with the described control functions. 8. A base station (BS) of the GSM mobile radio system for sending signaling information to at least one subscriber station (TS) in a first frequency frequency (F), having a method for transmitting a value group (ARFCN) by means of signaling information The device (GSM) of at least one element, wherein a first subgroup of said group of values (ARFCN) is used in the form of channel numbers to allocate frequency channels of said GSM mobile radio system, It is characterized by: A control device (ST) for signaling additional control functions beyond the frequency channel allocation of the GSM mobile radio system using elements of the second subgroup (N) of the value group (ARFCN). 9. Subscriber station (MS) of the GSM mobile radio system for receiving signaling information of at least one base station (BS) in a first frequency frequency (F), having a method for analyzing the information contained in said signaling information , a first analysis means of at least one element of a numerical group (ARFCN), wherein a first subgroup of said numerical group (ARFCN) is used in the form of channel numbers to allocate frequency channels of said GSM mobile radio system, It is characterized by: Second analysis means (AE) for analyzing at least one element in the second subgroup (N) of said value group (ARFCN), which element is used to transmit additional, beyond the frequency channel allocation of the GSM mobile radio system Control function signaling.

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