GB2378855A

GB2378855A - Simultaneous transmission of speech and data on a single channel

Info

Publication number: GB2378855A
Application number: GB0120001A
Authority: GB
Inventors: Frederic Heurtaux; Rafael Alos
Original assignee: Sagem SA
Current assignee: Sagem SA
Priority date: 2000-07-28
Filing date: 2001-08-16
Publication date: 2003-02-19
Anticipated expiration: 2021-08-16
Also published as: FR2812508B1; GB2378855B; FR2812508A1; GB0120001D0; DE10140549A1; DE10140549B4

Abstract

Speech signals and data signals are transmitted between a mobile phone 1 and a base station 4 on the same channel, with the speech signals and data signals each being transmitted at half the full bit rate of the channel. The half bit rate speech and half bit rate data signals may be interlaced in a half time slot, the time slot being divided into two half slots by a learning sequence (see fig. 3). The data may be transmitted in packet mode, with the packets being stored in a buffer memory 34 prior to transmission. The mobile phone may include a speech encoder-decoder 10 which is operable at half bit rate, and transmission of the speech signals may be downgraded from full bit rate to half bit rate. The base station may include means 18 for synchronising the speech and data signals. The method allows a mobile telephone to operate simultaneously in circuit mode and packet mode.

Description

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e Method for the simultaneous transmission of speech and data signals between a base station and a mobile telephone, and mobile telephone that can be used to implement the method 5 An object of the present invention is a method for the simultaneous transmission of speech and data signals between a base station and a mobile telephone, as well as a mobile telephone that can be used to implement the method. The aim of the invention is to provide for greater use of a mobile telephone even if this telephone belongs to a downgraded class 10 of telephone that is incapable, in principle, of carrying out certain functions.

More generally, the invention seeks to reduce the cost of mobile telephones by making it possible for basic, low-cost mobile telephones to work as well as mobile telephones that have improvements.

More specifically, the invention also seeks to enable the simultaneous 15 use of a mobile telephone in circuit mode and in packet mode.

Typically, the use of mobile telephones in circuit mode corresponds to the setting up of a circuit between two speakers or, as the case may be, between two data transmission devices. In this respect, the mobile telephone of the invention will not be limited to phonic use. It could also 20 serve, by means of a socket connector, as a modem for data transmission of this kind. For this purpose, this terminology will continue to be used herein even if it is not necessarily applicable to a phonic link. Operation in circuit mode results in the fact that, throughout the duration of a call, a communications channel is reserved for the call. Consequently, the user 25 pays rent for this channel in proportion to the duration of this call and independently of the transmission and reception of data.

Another known mode of transmission is the packet transmission mode.

In this case, packets are sent and each packet contains a designation of its addressee. The mobile telephones that are not addressees of the 30 information do not keep the contents of the packets that are not addressed to them in their memory. Furthermore, to prevent these mobile telephones from decoding all the packets received, including those not addressed to them, indicator signals sent by the transmitter give the receivers rendez-vous dates so that these receivers can limit themselves to decoding only signals 35 addressed to them. Conversely, for the transmission of signals from the

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mobile telephone to a base station, a system for the static or dynamic or, in turn, both static and dynamic assignment of transmission times is used to avert situations where different mobile telephones listening to one and the same channel cause collisions in the transmission of data signals to be sent.

5 The most important consequence of the packet transmission mode is of course the fact that the user pays for the channel only in proportion to the quantity of packets that are sent to him or that he sends.

In practice, a mobile telephone of this kind working in packet mode permanently listens to the packet transmission channel. It becomes an actor 10 using this channel following a procedure for setting up a link for signal transmissions on this second channel. This set-up link is a TBF (Temporary Block Flow) type of connection. This link has a finite duration, known in advance. The value of the duration is preset in preliminary indicator signals especially as a function of the quantity of data to be transmitted. If the 15 quantity of data to be transmitted is far too great, a basic duration TBF is set up and this duration is renewed at the end so long as all the information to be transmitted has not been transmitted. Ultimately, the user pays for the number of TBF periods that he has really used.

Mobile telephones used to implement these circuit communications 20 modes or packet communications modes may belong to three classes. The class C telephones, which correspond to the least efficient mobile telephones, have a command, dictated by the user, using for example a keypad, to make the mobile telephone work exclusively in circuit mode or in packet mode. Depending on its pre-selection when it is put into operation 25 and its recognition by the mobile telephony network, the mobile telephone sends a Cc type of signal to report its possible use in circuit mode or a Cg type signal (g- GPRS or Global Packet Radio System) to report the fact that it is configured as a packet receiver. Hereinafter in the explanation, reference shall be made preferably to the packet mode according to the GPRS 30 standard. However, it may be possible, in the context of the invention, to envisage a packet transmission mode that does not conform to the GPRS standard but to another standard.

As distinct from these class C devices working exclusively in one mode or another depending on an action by the user, it is possible to 35 distinguish class B devices in which the switching from a circuit mode to a

r . packet mode is automatic. The cost of class B devices differs little from the cost of class C devices. With a class B device, it is possible to implement a "suspend-resume" type of function during which it is possible to freeze a communications session in one mode, start another session in another mode 5 and then return to the first mode without having lost the information being distributed. It is also possible, for example in GPRS mode, to consult an Internet site and switch into speech mode during communication with a base station. It is not necessary, as with a class C device, to break the connection with the base station and reset the device by declaring another mode of use.

10 To simplify the explanations, it will be assumed here that the exchange protocols in the circuit mode as well as in the packet mode, in mobile telephony, are the same type, for example GSM (global system for mobiles) type protocols. For each of them, in the environment of a given base station, frequency relationships, transmission levels, transmission anticipation 15 periods and transmission and reception time slot allocations are defined.

Similarly, beacon channels can be differentiated. In practice, the mobility management mode gives rise to operating circuits which, in the circuit mode more particularly designed to provide this mobility, are different from those of the GPRS packet mode for which mobility is an additional accessory. In 20 practice, a class B mobile telephone is provided with a dual standby system to detect standard calls and GPRS service requests. This dual standby system can work on specific request (without resetting but, at the same time, not automatically) in one mode or another.

For the user, these operations are different. In practice, they require 25 fixed devices that are totally different in nature.

To have simultaneous operation in both modes, class A mobile telephones are provided. In practice, these class A mobile telephones have to be equipped with a dual transceiver to be able to both send and receive in one mode and in another, and to do so simultaneously. Naturally, the cost of 30 these class A devices is considerably higher than that of class B devices and of course higher than that of class C devices.

Invaluable information on the use of the GPRS transmission mode is given in Xavier Lagrange, Philippe Godlevski & Sami Tabbane, Reseaux GSM- DCS (GSM-DCS Networks) Hermes, France, third edition, September 35 1997, Page 326 and ff.

- a * The aim of the invention is to simplify the construction of mobile telephones, especially in the context defined here above, to enable class B mobile telephones or even class C mobile telephones to work like class A mobile telephones. The difference between class B or clash C mobile 5 telephones and class A mobile telephones lies essentially in the fact that class B and class C mobile telephones have only one transceiver device.

In the invention then, to provide for the simultaneity of use in circuit mode and in GPRS packet mode, or more exactly to provide for the simultaneity of the transmission of the speech signals and the data signals, it 10 is planned to use a property of mobile telephones wherein they are able to work in speech transmission at half bit rate. In this case, a CODEC, namely a speech encoder/decoder is used. This encoder is capable of working at half bit rate. Data signals are then concatenated with the speech signals to Arm signals delivered at ful! bit rate on a common transmission channel 15 These signals transmitted according to a full-bit-rate protocols are then decoded in reception, in the mobile telephone or the base station. Using extracted signals, the respective contributions are separated. The speech signals are processed as such. They are finally introduced into a CODEC working at half bit rate. The data signals are processed according to their 20 own mode.

Without immediately introducing the notion of frequency agility, a channel may be defined as the allocation of a time slot in a frame (in general frames with eight time slots, namely according to the TDMA or Time Division Multiple Access mode), and of a transmission (or reception) carrier 25 frequency. As a variant, in a COMA (Coded Division Multiple Access) type transmission mode, it is possible to define a channel by an allocation of a special encoding sequence. In any case, a frame corresponds to a quantified duration during which a given quantity of information is sent. To prevent any overlapping of signals and enable multiple communications with 30 telephones, it is planned that, with same time slots, different mobile telephones will use different carrier frequencies or, for the same carrier frequencies, they will use different time slots. In practice, the channel is then different. This is the same for the CDMA where the encoding sequence is different. 35 In the invention, when a packet communications channel is set up, a

t. i half-bit-rate availability for a given frequency relationship (corresponding in fact to the prevailing frequency relationship for mobile telephones) is measured. If need be, a downgrading of the bit rate is enforced to access this half bit rate. Then a request is sent for packet transmission. Time slots 5 common to those used in telephony by the mobile telephone are used, but for data transmission, preferably in packet mode. Thus, an overlapping of speech signals sent in circuit mode and data signals sent in packet mode is prevented. In this case, during these allocated time slots, data (preferably in 10 packet mode) and speech signals are transmitted to the mobile telephone on the same channel. It would be the same in COMA mode where one and the same encoding sequence would be used to transmit data and speech signals. Ultimately, with the invention, between the CODEC and the transmission/reception circuit of the mobile telephone, a 15 concatenation/deconcatenation circuit is interposed for the incorporation therein or extraction therefrom of the data signals and the speech signals.

The transmission/reception circuits for their part comprise circuits for the formatting of data to be transmitted in order to comply with a given protocol (TDMA, COMA etc.).

20 By acting in this way, especially by keeping the same frequency relationship, it is ensured that in one frame, during the transmission or reception periods, the mobile, especially in TDMA mode, is no longer concerned with frequency leaps. It is therefore immediately available. It is then possible to make transmission in circuit mode and transmission in 25 packet mode in one and the same time slot. The mobile telephone equipment needed consists then of only its transceiver and an additional operating software programme to comply with a common transmission protocol and bring together or separate different signals.

Furthermore, by acting in this way, inasmuch as the transmitted 30 signals come from one and the same base transceiver station (BTS), the channel encoding remains the same. This means that the matching of a channel filter of the decoder of the mobile telephone is immediate. At most, the mobile telephone must switch over to a mode of processing information received during each of the time slots. Those received in the circuit mode 35 must undergo a processing operation that corresponds to use in circuit mode.

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Those received in packet mode must undergo processing according to the packet mode.

In practice, the circuit mode will be mostly a telephony mode although it could also be a data transmission mode. By contrast, the packet 5 transmission mode will be rather reserved for data transmissions, such as transmissions reserved for visits to Internet sites.

An object of the invention therefore is a method of simultaneous transmission of speech signals and data signals between mobile telephones and base station of a mobile telephony network in which 10 first acoustic speech signals are converted into first electrical speech signals, - the electrical speech signals are transmitted on a transmission channel according to a first protocols characterized in that 15 - the first protocol is a half-bit-rate protocol, - electrical data signals are transmitted simultaneously with the electrical speech signals on the same transmission channel, in complementing the bit rate of the half-bit-rate protocol by these electrical data signals. 20 An object of the invention is also a mobile telephone comprising, in a memory, a first programme to implement a transmission of speech signals and a second programme to implement a transmission of data signals, characterized in that it comprises a circuit to extract or concatenate electrical speech signals with electrical data signals 25 The invention will be understood more clearly from the following description with reference to the accompanying figures. These figures are

given purely by way of an indication and in no way restrict the scope of the invention. Of these figures: Figure 1 gives a diagrammatic view of a communications system 30 between the base station and mobile telephones that can be used to implement the method of the invention; - Figures 2 and 3 are graphs showing a preferred mode of assembly and disassembly of data signals and speech signals according to the invention; 35 - Figure 4 gives a view of an improvement of the method of the

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d'. - - invention during the data transmission request, whether by packet transmission or not.

Figure 1 shows a system that can be used to implement the communications method according to the invention. The system has mobile 5 telephones 1, 2 and 3 that can get linked with a base station for the exchange, firstly, of speech signals and, secondly, of data signals. To simplify the explanation, hereinafter it will be assumed (but the reverse assumption can of course be envisaged) that the first signals are delivered in circuit mode and that they represent speech signals. It will also be assumed 10 that the second signals are delivered in packet mode and that they represent data signals. They result for example from the consultation of an Internet site. Indeed, in the context of the consultation of an Internet site of this kind, the sporadic transmission of signals leads to a situation where a large quantity of information can be transmitted in a very short time, followed by a 15 fairly lengthy period of time in which the user examines images resulting from the consultation on a screen of his mobile telephone. During this fairly lengthy period, no exchange is made. However, the signals could equally well be both delivered in circuit mode.

The telephone 1 works as follows. A transmission-reception circuit 5 20 of the telephone 1 is connected by a bus 6 to a microprocessor 7 implementing a general programme 8 for the management of the telephone 1. This general programme is contained in a memory 9 also connected to the bus 6. The bus 6 is also connected to an acoustic transmission-reception circuit 10 connected to a microphone 11 and a speaker 12 as well as to a 25 keypad 13 and the screen 14. The circuit 10 is a CODEC type circuit, namely a speech encoder-decoder. It produces electrical speech signals from acoustic speech signals and vice versa. In the invention, the circuit 10 is capable of processing electrical speech signals at half bit rate. Preferably, it is capable of processing signals at half bit rate and at full bit rate. In this 30 case, it can be switched under the control of the microprocessor 7. If need be, it is duplicated. The keyboard 13 and the screen 14 may be used to display or process data signals while the microphone 11 and a speaker 12 are used to process acoustic speech signals. A memory 15, connected to the bus 6, comprises a part with parameters. This part with parameters, in 35 particular, stores information on the frequency relationship enabling

-.... . - frequency agility as well as typical sequences of significant bits to be used as learning sequences or encoding sequences in CDMA mode. With the keypad 13, the user may compose data messages.

Figure 1 shows that the base station 4 is connected to;C or base 5 station controller circuits 16. These base station controllers in practice manage resources as well as the signalling to be applied so that the mobile telephones 1 to 3, in circuit mode, can respectively extract the signals that concern them from the signals that concern the other mobile telephones.

The BSC circuits at the same time convey signals coming from an RTC, 10 ISDN or similar telephone network.

Along with the equipment needed for transmission in circuit mode, there coexists equipment needed for packet mode transmission. In a general installation, circuits 17 known as PCUs or packet contro! units are used to transmit data packets, especially coming from O! addressed to the!nternet 15 network. The PCU circuits on the whole play the same role as the BSC circuits. In principle, the BSC circuits are independent of the PCU circuits. In particular, the mobile telephones have to use different channels depending on whether they have to exchange speech or data. In the invention, advantageous use is made of the fact that the telephone 1 is already locked 20 into a channel in order to preferably send data packets in the same channel: in particular, on the same frequency and especially during the same time slots as those used for speech transmission.

To this end, it may be desired that the PCU circuits 17, using a synchronization link 18, should conduct a preliminary interrogation of the 25 BSC circuits to know which channel has been imposed by these BSC circuits. Then, the PCU circuits 17 organise their distribution as a function of the available resources in the frame of this channel. The PCU circuits 17 have no need to be synchronized with the BSC circuit 16. Their zero order time slots thus do not need to occur at the same time. If there is no 30 synchronization, it is necessary all the same to identify the time slots in one mode in order to give them a corresponding rank in the other mode. The link 18 symbolically represents the operations implemented by the PCU circuits 17 to obtain this result. Further below, we shall see how this synchronization can be obtained in the mobile telephone, simply by means of a buffer 35 memory and how the use of such a buffer memory managed by only one of

r --: the devices, typically the circuit 16, resolves this problem.

Figures 2 and 3 provide for an understanding of the way in which the speech signals are sent at full bit rate and, by comparison, at half bit rate.

They also show how the available resources left by the data transmission at 5 half bit rate will be used. Figure 2 shows the constitution of data blocks by an encoder-decoder 10 in a full-bit-rate mode. The signalling is sampled in 20-

millisecond periods in a standardised way at 13 kHz, and each sample is quantified on 13 bits. The resulting bit rate, which may be in the range of 64 kilobits per second, is far too high to be transmitted by the mobile telephony 10 channels. The type 10 circuits are then designed to reduce this bit rate to 13 kilobits per second so that, for each 20- millisecond period, they produce 260 useful bits. In practice, these bits represent filtering coefficients of a filter capable of modelling the voice of the speaker as well as information that itself has to be transmitted.

15 The signals thus encoded by the CODEC circuit 10 undergo a channel encoding that provides redundancy capable of withstanding disturbances in the transmission channel. The bit rate then becomes 456 bits per 20 millisecond period. This bit rate is actually a total bit rate. For its transmission, it is distributed on periods of four full frames and, additionally, 20 signalling periods. The 456-bit data blocks, each bit being referenced be to b455, are stored in a working memory 19 of the microprocessor 7. The bits of the blocks are written in row recordings, each comprising eight bits, by a write cursor 20. For use, at the time of the transmission, they are extracted from the memory 19 by a column read cursor 21. This procedure prompts 25 firstly a rearrangement of the bits produced by the encoder 10 and, secondly, a splitting of a 456-bit block into eight words of 57 bits. According to a preferred alternative, these eight 57-bit words, referenced MO to M7 for a 456-bit block M, NO to N7 for a following 456-bit block N and so on and so forth for blocks P. Q etc. are transmitted in what is called a diagonal 30 interlacing with respect to one another as follows. Each of the words MO to M7 is transmitted during a frame of a group of eight successive frames.

Figure 3 thus shows that the frames 22 to 29 are acted upon.

The bottom part of figure 3 gives a view, in a time slot 30, of the frame 56 which is allocated to the mobile telephone 1 of the concatenation of the 35 57-bit word of the block M with the 57-bit word NO of the block N which

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follows the block M in time as and when they are edited by the encoder 10.

At least two solutions of concatenation of the word M4 and of the word MO can be envisaged. A preferred solution comprises the assignment of the significant even parity bits of the time slot 30 to convey the 57.bits of the 5 word M4, and the assignment of the significant odd parity bits of the time slot 30 to send the 57 bits of the word NO. In the frame 26, the digital signal thus constituted furthermore has a learning sequence 31 comprising 26 bits placed in intermediate position. The 29 even parity bits 0 to 56 of the first half slot 32 prior to the sequence 31 in the slot 30 are assigned to the word 10 M4 and the 28 odd parity bits 1 to 55 are assigned to the word NO. The other significant bits 28 and 29 of the word M4 and MO respectively occupy the even-parity positions 58 to 112 and odd-parity positions 57 to 113 in the second half slot 33 following the sequence 31.

Rather then proceed in this manner; it would have possible simply to 15 choose to send the 57 bits of the word M4 during the period 32 and the 57 bits of the word NO during the period 33. This is shown by the bottom of figure 3. Furthermore, if a diagonal interlacing had not been chosen, the word M4 and the word M5 would have been sent together during the period of the time slot 30.

20 According to the invention, the encoder 10 will be an encoder capable of a half bit rate. In practice, it will produce 260 bits only every 40 milliseconds. With the preliminary channel encoding, a bit rate of 456 bits is obtained for 40 milliseconds. It all happens as if, after 40 milliseconds of waiting (which is imperceptible to the human ear), the words MO and M7 are 25 available and it is necessary to wait again for 40 milliseconds to have available the words PO to P7, the words NO to N7 being not yet produced. At reception, the decoder 10 is matched to reproduce the sound of the speaker's voice (slightly less faithfully than a full-bit-rate encoder).

In the invention, in a simple approach, the block N not produced is 30 replayed by a data block coming from another source or designed for another accessory of the mobile telephone. For example, it my happen that the data blocks were transmitted by the circuits 17 for display on the screen 14 or else they may have been produced by the keyboard 13 (or any other means) to be sent to the circuits 17.

35 In general the data to be transmitted are formatted in a special

,: ;.e.; * protocol with the formatting of speech signals. For example, the data to be transmitted may take the form of data blocks D and E and so on and so forth, each with 460 bits, which too have to be processed by a memory of the same type as the memory 19 to produce 57-bit data words of 57 bits DO to D7, EO 5 to E7 and so on and so forth.

In a buffer memory 34, figure 1, following are then stored alternately: the speech block M (the words MO to M7, the data block D (the words DO to D7), the speech block B (the words BO to B7), the next data block E (the words ED to E7) and so on and so forth. All that is needed then for the 10 transmission of all the bits is to use the concatenation thus constituted to fill the time slots 30 of the frame 36 with a sufficient number of bits.

Ultimately, in transmission, instead of the encoder 10 producing 260-

bit blocks which the microprocessor 7 processes to give them channel redundancy (456 bits) and organises to arrange them in consecutive 57-bit 15 words, the microprocessor 7 performs this work alternately on 260-bit blocks coming from the encoder 10 and on 260-bit blocks coming from a data-

processing circuit (managed in practice by the processor 7 itself). The processor 7 therefore alternately produces speech words MO to M7 and data words BO to B7. In practice, the row 35 of figure 3 represents this alternate 20 production of the words Mi and Di while the next row 36 shows a concatenation of these words of different types in common time slots 30 with a common frame 26. It all happens as if the blocks N had been replaced by the blocks D. The telephone 1 is then characterized by the fact that is comprises a programme to send or receive full-bit-rate RF means while its 25 speech encoder works at half bit rate.

Naturally, the transmission of the data blocks can be done in packet mode. In this case, the telephone mobile 1 or the base stations, by means of a preliminary signalling, (yarn each other and together institute TBS durations corresponding to the quantity of digital data signals to be sent. In this case, 30 the user is invoiced firstly for a half-bit-rate use in circuit mode for the speech blocks M or P and so on and so forth, and, secondly, for a transmission of half-packets (for example at half cost) for the sending of half-packets D and E and so on and so forth.

In the memory 34, it is possible to write the blocks M, D, P. E 35 differently depending on whether they are speech block or data blocks.

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.. . When they are speech blocks, they cannot be written except gradually depending on what is said by the speaker. However, the data blocks may be available massively at the given point in time. In this case, in the memory 34, they will be split into 260-bit blocks (then encoded with a channel Encoding to 5 obtain 456-bit words) and recorded in the memory 34, one recording in two, so that it is possible to have them available regularly as and when they are needed. In this case, the memory 34 may also be replaced by a processor 7 that is fast enough and capable of performing all the processing operations on the fly and alternately.

10 In both transmission and reception, the programme implemented by the microprocessor 7 will be a half-bit-rate programme known as a GSM1/2 programme when speech signals are to be transmitted alone and a full-bit rate programme knowr, as a GSM programme, when the slots 30 have been filled by additional data transmission. In reception, the microprocessor 7 will 15 be responsible for separating (one significant bit in two the case of the diagonal interlacing) the data signals from the speech signals.

Figure 4 shows a particular mode of operation of the invention. It ispossible that the user will use his encoder 10 at full rate most of the time.

Consequently, when he wishes to make simultaneous use of speech 20 transmission and data transmission, the programme 8 of the memory 9 comprises a concatenation or separation sub-routine 37. This sub-routine 37, after signalling steps which set up the possibility of producing data signals and speech signals simultaneously, comprises a step 38 for the measurement of a need to send data signals. When such a need is noted, 25 the programme 37 makes the microprocessor 7 carry out the test 39 to find out if the microprocessor is making the encoder 10 work at full rate or at reduced rate. If the encoder 10 is working at full rate, the microprocessor will prepare an instruction 40 to force the encoder 10 to work at a reduced rate.

This change in bit rate may be preferably associated with a preliminary 30 negotiation with the infrastructure before it takes place. Consequently, the distant party may be informed of the change in encoding. Following this enforcing operation 40, the microprocessor 7 implements a concatenation 41 of the speech and dataibits as represented diagrammatically in the row 35.

In this case, the transmission of the speech signals is temporarily 35 downgraded from full bit rate to half bit rate. If, on the contrary, the full bit

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rate is necessary, it may be planned to prevent the enforcing and, this case, the data are temporarily not transmitted.

If the data transmission is done in packet mode, there are several users listening to the transmitted packets. These users are all listening to a 5 channel which, furthermore, is a channel allocated, for another half bit rate, to a single user. For example, the user of the mobile telephone 2 could himself also be in a data link with the Internet. To make it possible then for the telephone 1 to know which is the addressee of the transmitted data packets, and given the unforeseeable nature of the sending of these packets (they are 10 sent during periods of communications silence whose distribution is random in principle), it is possible to provide for two solutions. In a first solution, with preliminary signalling, it is possible to designate an addressee. As a variant, in the learning sequences which are part of the data transmission mode, it is possible to distinguish learning sequences that can be used by the telephone 15 1 to receive data in addition to the phonic signals and learning sequences that can be used by the mobile telephone to receive data in addition to the phonic signals. In decoding, only the telephone that recognizes its data reception learning sequences uses the information.

The result of this organization is that the mobile telephone according 20 to the invention has only one transmission chain (in transmission and reception) to simultaneously exploit the packet data transfer and speech data transfer modes in one in the same protocols. Naturally, a single transmission chain of this kind for these two modes does not run counter to the possibility that the mobile telephone might possess another chain using another 25 protocol (in particular the UMTS protocol) because the technology proper to this other protocol would dictate a different chain.

Claims

_ 7 do; À À À À r. e CLAIMS

1. Method for the simultaneous transmission of speech signals and data signals between mobile telephones and a base station of a mobile 5 telephony network, wherein - first acoustic speech signals are converted into first electrical speech signals, - the electrical speech signals are transmitted on a transmission channel according to a first protocol, 10 characterized in that - the first protocol is a half-bit-rate protocol, electrical data signals are transmitted simultaneously with the electrical speech signals on the same fu,l-bit-rate transmission chance', the half-bit-rate speech signals and the data signals.

15

2. Method according to claim 1, characterized in that the interlacing between the data signals and the speech signals is done in a half slot.

3. Method according to one of the claims 1 or 2, characterized in that a slot comprises a learning sequence dividing the slot into two half slots.

4. Method according to one of the claims 1 to 3, characterized in that 20 - the electrical data signals are transmitted in packet mode.

5. Method according to one of the claims 1 to 4, characterized in that data packets to be transmitted are stored in a buffer memory t34), - and the electrical data signals are transmitted by being extracted from this buffer memory.

25

6. Method according to one of the claims 1 to 5, characterized in that - a type of operation of a vocoder of the mobile telephone is measured (39), and - data signals to be transmitted are transmitted as a function of this type of operation.

30

7. Method according to one of the claims 1 to 6, characterized in that - a transmission is downgraded (40) from a full bit rate to a half bit rate of the speech signals.

8. Method according to one of the claims 1 to 7, characterized in that, with the base station being provided with first circuits for the management of 35 the transmissions of electrical speech signals and second circuits for the

a, À À e e management of the transmissions of electrical data signals, synchronization signals are sent (18) from the first to the second circuits, or vice versa and - the operations of sending the electrical signals are synchronized.

5

9. A mobile telephone comprising, in a memory (9), a first programme (8) to implement a transmission of speech signals and a second programme to implement a transmission of data signals, characterized in that it comprises a circuit (37) to extract or concatenate electrical speech signals with electrical data signals by de-interlacing them or interlacing them.

10 10. A telephone according to claim 7, characterized in that it comprises a circuit (34) to interlace the speech signals with the data signals.

11. A telephone according to one of the claims 7 to 8, characterized in that it has a programme for making RF transmission and reception at full bit rate with a speech encoder working at half bit rate.

15

12. A telephone according to one of the claims 7 to 9, comprising a single transmission/reception chain (5) for the simultaneous transmission of data in packet mode and speech in circuit mode.

13. A method substantially as hereinbefore described with reference to the accompanying drawings.

20

14. telephone substantially as hereinbefore described with reference to the accompanying drawings.