NZ264726A

NZ264726A - Cellular radio telephony: indication of type of information channel message to be sent transmitted to mobiles over signalling channel

Info

Publication number: NZ264726A
Application number: NZ264726A
Authority: NZ
Inventors: Eric Desorbay; Michael Roberts
Original assignee: Alcatel Australia
Priority date: 1993-10-26
Filing date: 1994-10-19
Publication date: 1996-11-26
Also published as: ATE194745T1; DE69425216T2; EP0650306A1; DK0650306T3; EP0650306B2; EP0650306B1; FR2711865A1; FR2711865B1; AU7588694A; DE69425216D1

Abstract

The present invention relates to a method of signalling, intended for mobile stations belonging to a radio communications system, particularly using: - an information channel intended to be received by one or more mobile stations, and on which messages called information messages are sent, containing information which is useful for the mobile stations, - a signalling channel on which the mobile stations are continuously active in reception, and on which messages, particularly messages known as signalling messages are sent, characterised in that it consists, before sending of an information message on the information channel, in sending a message, called indication message, on the signalling channel in order to indicate to the mobile stations the type of the next information message which will be sent.

Description

<div class="application article clearfix" id="description"> "J i** p Priority Date(s): Complete Specification Fifed:... tiass: (6).. ftp.H:2a| i...3*. Publication Date: 2..8..N.D.V...1996. 0 O, Journal No: J!t^.! 64 72 6 Ul; '.Z. PATENT OFFICE 19 OCT 1994 RECEIVED TRUE MOT NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION " SIGNALLING METHOD FOR MOBILE R, >DIO " WE, ALCATEL AUSTRALIA LIMITED, 6f»OM ooX> **** 3fc^ A Company of the State of New South Wales, of 280 Botany Road, Alexandria, New South Wales, 2015, Australia, hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 1 2® 4 7 This invention relates to signalling and control processes used in a radiocommunications system, together with a base station and a mobile station to implement these processes. In most known cellular mobile radio systems, there is a Cell Broadcast Channel (CBCH according to GSM terminology) which is specific to each cell and designed for broadcasting generally short information messages to mobile stations roaming within the cell involved. The information broadcast relates in particular to road traffic conditions or weather forecast, it may also contain advertising messages. For reasons of clarity, this channel (or equivalent channels in other systems) shall be referred to as information channel hereinafter. The information is made available to the user of a mobile station (a mobile phone for instance) in the form of a text message displayed on the mobile phone screen, or in the form of a voice message when the broadcast channel is a voice channel. In order to receive this information, a mobile phone must be "listening" to the information channel, i.e. it must be tuned in to this channel. Nevertheless, it may happen that sometimes no information message is broadcast over the information channel. This could be due to the fact that there is no new information to broadcast for instance. Since mobile stations have no way of knowing at which moment no information will be broadcast, they have to be permanently active and set to 2 26 4 72 receive over the information channel, consequently, this is sometimes unnecessary. The same applies when the information broadcast is of no interest to the mobile station user. Having to be continuously tuned in to a channel likely to contain no information, or some information of no interest to the user, leads to a significant power consumption for a portable mobile phone in particular. Yet, we know that one constant concern is to reduce mobile phone consumption to ensure that the batteries last as long as possible. Therefore, the purpose of the present invention is to develop a signalling process whereby mobile stations do not have to unnecessarily be tuned in to the information channel, together with a control process aimed at mobile stations using the information broadcast within the signalling of this signalling process. According to the invention, there is provided a signalling process for mobile stations belonging to a cellular mobile radio system, comprising an information channel designed to be received by one or several of the said mobile stations, and over which are transmitted the said information messages containing information which is useful to the said mobile stations, a signalling channel the mobile stations are permanently tuned in to and over which signalling messages are transmitted, wherein said signalling process comprises sending an indication message over the said signalling channel, prior to transmission of an information message over the said information £§ 4 7 2Q * channel, to inform the said mobile stations of the type of the next information message to be transmitted. In accordance with the process of the invention, the channel used to inform the mobile stations of the type of the next information message to be 5 transmitted, is the channel the mobile stations must be permanently tuned in to. Consequently, this process does not lead to additional power consumption by mobile stations since they must be permanently tuned in to the signalling channel; furthermore, the process in accordance with the 10 invention ensures optimum resource utilisation; finally, it allows the mobile stations to choose according to certain criteria (user-selected or preset) the information they wish to listen to, this saves the energy available at mobile station level and consequently increases their autonomy. According to an advantageous method of implementation, the 15 indication message used can be contained either in the filler message 0b transmitted over the signalling channel when no signalling message is transmitted to the mobile stations, or in a signalling message containing useful information and having some bits available, these bits then being used to contain the indication message. 20 Resources that are not utilised in the signalling channel are put to good use to transmit the indication messages. In a specific application of the process in accordance with the 4 » £6 4 72 invention, the radiocommunications system is a digital cellular mobile radio system using the time division multiple access principle; the information channel is a time slot repeated according to a preset cycle, and the signalling channel is a time slot also repeated according to a preset cycle, such that a signalling channel time slot always precedes an information channel time slot. In the above specific application, the signalling channel may be a paging channel over which messages are transmitted to mobile stations, these messages being either signalling messages, called paging messages designed to warn that a fixed or mobile subscriber is trying to contact them, or filler messages. The process in accordance with the invention can, for instance, indicate three types of information messages: - Type one, called general information messages, containing general information intended for mobile stations. - Type two, called emergency messages, containing information to be urgently transmitted to the mobile stations. - Type three, called filler messages, being transmitted when no general message or no emergency message is to be transmitted. A mobile station control process in a radio system using a signalling process such as the one described above, consists, after reception of an indication message informing of the transmission of an information message over the information channel, of controlling the mobile station to tune in to, or 264 72 out of, the information channel, depending on the type of information message. In particular, such a process consists, after reception of an indication message informing of the transmission over the information channel of a type two or type three message, of controlling the mobile station to tune in to, or out of, the information channel. Furthermore, it may consist, after reception of an indication message informing of the transmission over the information channel of a type one message, of controlling the mobile station to tune in to the information channel. When the indication message also indicates the category of type one information message, the process may consist of controlling the mobile station to tune in to the information channel only if this category corresponds to a preselected category. The present invention also relates to a base station used to implement the process in accordance with the invention, including: - a radio signal transmission device used in particular to transmit the information messages and signalling messages, in the form of radio signals. - a control device used to control the transmission devices such that the latter transmit, in the form of radio signal, the indication messages corresponding to the type of the next information message it is about to transmit. Finally, the present invention relates to a mobile station used to 26 4 implement the process in accordance with the invention, including: - a radio signal reception device - a radio signal processing device used to process the signals received and in particular the indication messages. - a control device used to tune the reception device in to or out of the information channel, depending on the type of the next information message. This mobile station may also include a selection device allowing the user to select to activate the reception device in accordance with the type of information message indicated. In order that the invention may be readily carried into effect, embodiments thereof will now be described in relation to the accompanying drawings, in which: - Figure 1 shows the layout of various data transmission channels going from the base station of a digital cellular mobile radio system to a mobile station within this system. - Figure 2 represents the block diagram of a base station used to implement the process in accordance with the present invention, together with its components involved in the present invention. - Figure 3 represents the block diagram of a mobile station used to implement the process in accordance with the present invention, together with its components involved in the present invention. Common components bear the same item number in all these figures. Z64? The following description refers in particular to a digital cellular mobile radio system in accordance with GSM standards. It should of course be understood that this particular explanation is given as an example only, and that the invention applies all the same to other radiocommunications systems. In systems in accordance with GSM standards, the information channel exists only when mobile stations are in standby, i.e. in a few words, when they are not in communication with another fixed or mobile subscriber. Data transmission being governed by the principle of time division multiple access (TDMA), the data transmitted are organised in frames or multiframes, each channel being made up of one or several time slots within a multiframe, repeated according to a preset cycle in time. More specifically, in the case of an ordinary cell of low capacity, the data transmitted by the base station to the mobile stations in standby is organised into multiframes, each multiframe containing 51 frames, and each frame containing eight time slots. Figure 1 shows a 51 frame multiframe contained in a T shaped table with eight rows (L1 to L8) and 51 columns. The first time slots of each of the 51 frames are represented side by side in the first row (L1), the second time slots of each of the 51 frames are represented side by side in the second row (L2), and so on. When moving in the T table from column to column, time goes by in the direction of arrow (10). 8 26 4 7 From base station to mobile station, the first time slot (ITO) of each frame is reserved (according to a well known method) to signalling intended for the mobile stations. More specifically, the first two ITO in row ".1 are respectively reserved for the frequency control subchannel (?) and the synchronisation subchannel (S). This means that subchannel F consists of a time slot repeated every 10 frames, as shown in figure 1. The four following ITO are reserved to the common signalling channel (B) (this channel is called Broadcast Control Channel in GSM terminology), and the four following ITO, as well as all the other ITO not reserved to subchannel F or S, are dedicated to the paging subchannel (P); paging subchannel (P) is a signalling channel designed namely to warn a mobile station that another fixed or mobile subscriber is trying to contact it. When this is effectively the case, some time slots of paging channel (P) are replaced with some time slots of an allocation subchannel (not illustrated) to allocate to the mobile station a traffic channel for the transfer of speech data for instance. Once a traffic channel has been allocated to a mobile station, the latter goes into dedicated mode, such that channels P and C are no longer used for this mobile station. Row L2 shows that the information channel (CBCH) (item C), in the configuration given as an example, is made up of four time slots (IT1) (i.e. four "second" time slots) per multiframe, these time slots immediately 9 % 6 4 7 2 i following two time slots of paging subchannel P, one time slot of subchannel F, and one time slot of subchannel S, respectively. In general, the time slots used for channel C can change from one cell to another; their ranks in a 51 frame multiframe are indicated to mobile stations within a given frame in the signalling transmitted over channel B (it is reminded that at this stage, mobile stations are synchronised with the base station, such that they know exactly the organisation of the data frames within the 51 frame multiframe and that the mere indication of the rank of the time slot within this multiframe lets them know exactly the time position of this channel). No further detail will be given on the allocation of other time slots of the 51 frame multiframe, since this description is not necessary for the remainder of the invention description. For further explanation on the role and organisation of the various channels, reference may be made to pages 206 to 212 of "The GSM System for Mobile Communications" by M. MOULY and M.B. PAUTET. The management network of the cellular mobile radio system considered continuously transmits signalling messages over paging channel P. Each message is addressed to a group of mobile stations located within the corresponding cell. These signalling messages, called paging messages, are different depending on the groups of mobile stations they are intended for within the cell. 10 6 4 2 5 When one of the mobile stations within a group wants to set up a call, a signalling message is transmitted to the group to which this mobile station belongs; it is received by all mobile stations within the group, although it is intended for one of them only. When none of the mobile stations within a group want to set up a call, a filler message is transmitted. This message has no meaning but provides for continuous transmission over paging subchannel P; as already mentioned, mobile stations are continuously tuned to this channel such that they can be warned as soon as a call is to be set up. As seen before, the network transmits over the information channel some information messages relating for instance to road traffic conditions or weather forecast, etc. When no information message is to be transmitted, filler messages are transmitted instead. According to the invention, to prevent mobile stations from having to be continuously tuned in to channel C, they are told which type of information message(s) is to be transmitted next, by means of an indication message transmitted over paging subchannel P. Information message can be sorted according to three types: - Type one, called general information messages, containing general information intended for mobile stations. - Type two, called emergency messages, containing information to be urgently transmitted to mobile stations. 11 26 4726 - Type three, called filler messages, transmitted when no type one or type two message is to be transmitted. After having processed the indication message received, and according to a first possible operating mode, each mobile station can decide whether or not to listen to the next information message(s). According to an improved version of the above process, the indication message may assume the functions of control message, i.e. that it be automatically followed by an action at receiving mobile station level, depending on the user-selected configuration or on the configuration preset at driver software level. Hence, according to a second possible operating mode, this driver software may be designed such that, when an indication message warns of the transmission over the information channel of a type two or three message, it automatically controls the mobile station to tune in to, or out of, the information channel. According to this operating mode, it can also be envisaged that, when an indication message warns of the transmission over the information channel of a type one message, the software let the mobile station decide (according to a user-selected option for instance) either to listen to the information message irrespective of its contents, or to listen to it only if it belongs to a category interesting the user (advertisements, weather forecast, road traffic conditions, 12 2 e 4 7 2 $ "interesting" categories having been selected beforehand by the user by means of appropriate interface). Using paging subchannel P to transmit indication messages is particularly worthwhile. 5 Indeed, firstly, the time slots reserved to paging subchannel P in the 51 frame multiframe are numerous (ref. figure 1), such that they are repeated with a recurrence higher than that of the time slots corresponding to information channel C, and always before transmission of the latter. This makes it possible to transmit suitable indication messages prior to each transmission over 10 information channel C. Furthermore, when no paging message is to be transmitted over paging subchannel P, instead of transmitting a filler message, the corresponding time m ^ slots can be used to transmit an indication message. Finally, transmitting paging messages a time when an indication message 15 ought to be transmitted does not pose any problem since paging messages do £ not use all available bits. These available bits can be put to good use to transmit the required indication messages. Besides, each paging message is generally addressed only to some mobile stations within the relevant group, such that even if a paging message is 20 transmitted, its available bits can be used to reach the mobile stations which are not concerned by its contents. To implement the process in accordance with the invention, a base 13 26 4 721 station (20) of the cellular mobile radio system includes (ref. figure 2). - A radio signal transmission device (21) used to transmit the information messages and signalling messages, namely paging messages and associated filler messages, in the form of radio signals. - A control device (22) which, under the control of a device (23) belonging to the management network of the cellular mobile radio system considered, is programmed to control the transmission device (21) such that the latter transmit, in the form of radio signal, the indication messages corresponding to the type of the next information message they are about to transmit. Furthermore, to implement the process in accordance with the invention, a mobile station (30) includes: - A radio signal reception device (31) - A radio signal processing device (32) used to process the signals received and in particular the indication messages. - A control devices (33) used to activate or deactivate the reception device (31) depending on the type of the next information message. Device (33), including for instance a driver software, is programmed according to one of the operating modes described. According to one of these operating modes, the mobile station (30) may also include a selection device (34) allowing the user to select to activate the reception device (31) according to the type of information message indicated, 14 / T O U t / 4 and according to the category of type one messages the user actually wishes to listen to. Of course, the present invention is not limited to the method of implementation described above. In particular, the above description relates to a digital cellular mobile radio system in accordance with GSM standards, and consequently having a preset and precise channel organisation. Nevertheless, the invention generally applies to any radiocommunications systems having an information message broadcast channel which is not continuously used. To transmit indication messages, it is not necessary to use a paging channel. Any signalling channel, over which the mobile stations must be continuously tuned in to, and having some resources available to insert the required indication messages, can be used. Moreover, it is preferable that this channel has a sufficient recurrence to be able to warn mobile stations prior to the transmission of each information message, though this characteristic is not necessary. In fact, it is sufficient to be able to transmit indication messages often enough, each indication message then relating to one or several consecutive information messages to come; in this case, one could envisage to provide within the mobile stations some means of storing the information contained in the indication messages, to use them later as necessary. 15 2d4 7 Hence, in all of the above, referring to the next information message can also mean the next information messages. Besides, the procedure described occurs entirely when mobile stations are in standby mode, since according to GSM standards, information (C) and paging (P) channels are only used in this mode. Nevertheless, this is not an essential characteristic of the present invention, and the latter applies all the same to other systems having the channels defined above although their use may not be reserved for the standby mode. Finally, any device may be replaced with an equivalent device without leaving the scope of the invention. 16 </div>

Claims

<div class="application article clearfix printTableText" id="claims"> 204 7 What we claim is:

1. A signalling process for mobile stations belonging to a cellular mobile radio system, comprising an information channel designed to be received by one or several of the said mobile stations, and over which are transmitted the said information messages containing information which is useful to the said mobile stations, a signalling channel the mobile stations are permanently tuned in to and over which signalling messages are transmitted, wherein said signalling process comprises sending an indication message over the said signalling channel, prior to transmission of an information message over the said information channel, to inform the said mobile stations of the type of the next information message to be transmitted.

2. A process as claimed in claim 1, wherein the indication message used can be contained either in the filler message transmitted over the signalling channel when no signalling message is transmitted to the mobile stations, or in a signalling message containing useful information and having some bits available, the said available bits then being used to contain the said indication message.

3. A process as claimed in claims 1 or 2, wherein said radiocommunications system is a digital cellular mobile radio system using time division multiple access principle, wherein the common channel comprises a time slot repeated according to a preset cycle, and wherein said signalling channel comprises a time slot also repeated according to a preset cycle, such 17 %64 7 that a signalling channel time slot always precedes an information channel time slot.

4. A process as claimed in any one of the preceding claims, wherein said signalling channel is a paging channel over which messages are transmitted to mobile stations, these messages being either signalling messages, called paging messages, and designed to inform them that a fixed or mobile subscriber is trying to contact them, or filler messages.

5. A process as claimed in any one of the preceding claims, wherein it allows indication of three types of information messages: - Type one, called general information messages, containing general information intended for the said mobile stations. - Type two, called emergency messages, containing information to be urgently transmitted to the said mobile stations. - Type three, called filler messages, transmitted when no type one or type two information message is to be transmitted.

6. A mobile station control process in a radio system using a process as claimed in any one of claims 1 to 5,comprising after reception of an indication message informing of the transmission of an information message over the said information channel, of controlling the said mobile station to tune in to, or out of, the said information channel, depending on the type of information message.

7. A mobile station control process in a radio system using a process as claimed in any one of claims 1 to 5,comprising after reception of an indication 18 264 72 message informing of the transmission over the said information channel of a type two or type three message, of controlling the said mobile station to tune in to, or out of, the said information channel.

8. A process as claimed in claim 7, comprising after reception of an indication message informing of the transmission over the said information channel of a type one message, controlling the said mobile station to tune in to the information channel.

9. A process as claimed in claim 7, wherein after reception of an indication message informing of the transmission over the said information channel of a type one message also indicating the category of the said type one information message, it consists of controlling the mobile station to tune in to the said information channel only if the said category corresponds to a preselected category.

10. A base station for implementing the process in accordance with any one of claims 1 to 9, including a radio signal transmission device used in particular to transmit the said information messages and signalling messages, in the form of radio signals and a control device used to control the said transmission device such that the latter transmits, in the form of radio signal, the said indication messages corresponding to the type of the next information message it is about to transmit.

11. A mobile station for implementing the process as claimed in any one of claims 1 to 9, including a radio signal reception device, a radio signal 19 4 72 § processing device used to process the signals received and in particular the said indication messages, and a control device used to activate or deactivate the said reception device to tune in to or out of the said information channel, m w depending on the type of the next information message. 5

12. A mobile station as claimed in claim 11, including a selection device allowing the user to select to activate the said reception device as claimed in the type of information message indicated.

13. A signalling process substantially as herein described will reference to Figures 1 - 3 of the accompanying drawings. 10 ALCATEL AUSTRALIA LIMITED P.M. Conrick Authorized Agent P5/1 /1703 15 </div>