EP3317981A1

EP3317981A1 - Apparatus for direct communication by mobile terminals

Info

Publication number: EP3317981A1
Application number: EP15736220.3A
Authority: EP
Inventors: Hanan ARMONI; Saar SHLAPOBERSKY
Original assignee: Dmonetworks AG
Current assignee: Dmonetworks AG
Priority date: 2015-07-01
Filing date: 2015-07-01
Publication date: 2018-05-09
Also published as: CA2980639A1; AU2015400700A1; WO2017001007A1; US20180069623A1; US10686519B2

Abstract

The invention relates to an apparatus for direct communication in simplex mode between mobile terminals, particularly mobile telephones (6), using carrier frequencies of a cellular mobile radio system, wherein each carrier frequency transmits TDMA frames (1) having a TDMA frame length of 4.615 ms and each TDMA frame comprises 8 timeslots (2) having a length of 577 µs, wherein the apparatus comprises a hardware module (4) that controls the direct communication, wherein the apparatus is designed to combine TDMA frames to form a multi-frame (3) that comprises 13 TDMA frames with the positions 0 to 12, and is designed such that the terminals involved always send and receive in separate timeslots (2) in simplex mode and, within each multiframe (3), only the first timeslot (2) TS0 in each TDMA frame (1) is used for sending or receiving, while the other timeslots (2) TS1 to TS7 of the TDMA frame (1) remain free.

Description

Device for direct communication of mobile terminals

The invention relates to a device for direct communication of mobile

Terminals and a mobile phone with such a device.

In cellular mobile networks, in particular the globally widespread GSM standard, for mobile voice and data transmission between mobile terminals, the digital data with a mixture of frequency division multiplexing and

Time Division Multiple Access (TDMA) transmitted, wherein transmit and receive band are provided in different frequency bands. The GSM frequency band is divided into several channels spaced 200 kHz apart. For GSM 900, in the range of 890-915 MHz, there are 124 uplink (uplink) channels to the base station, and in the 935-960 MHz range, 124 channels for the

Downlink provided. The TDMA frame duration is approximately 4.615 ms and corresponds to the duration of exactly 1250 symbols. Each of the eight time slots per frame thus takes approximately 0.577 ms, corresponding to the duration of 156.25 symbols. In these timeslots, bursts of different types can be sent and received. The duration of a normal burst is approximately 0.546 ms, during which 148 symbols are transmitted.

After sending a receiving burst, the mobile phone switches to the 45 MHz offset transmission frequency in the GSM standard and transmits the burst of the

Return channel to the base station. Since downlink and uplink occur offset by three time slots, an antenna is sufficient for the transmission of downlink and uplink. A cellular mobile radio system, in particular a GSM-based

Communication system, but always requires an upright network, which is supplied by one or more base stations. Communication of the terminals with each other without upright GSM network is not provided with conventional GSM-based mobile terminals, but would be desirable in order to

exceptional situations, especially in case of disaster, to enable a rudimentary communication between mobile devices. Such a rudimentary communication may in particular be a communication in simplex mode, ie a communication in which only one terminal always transmits. In the following, this rudimentary simplex communication, as opposed to always operating in duplex mode conventional GSM connection as

Direct communication or direct mode (direct mode).

Devices for direct communication of mobile terminals in simplex mode without GSM base station have long been known from the prior art; the

However, communication is via proprietary frequency bands, so the

Use of proprietary transmitter and receiver is required. The devices can therefore not be used with conventional GSM mobile phones.

The object of the invention is therefore to improve the known devices for direct communication in simplex mode and to provide a device which makes it possible to adapt an existing GSM-based mobile phone in a simple manner for direct communication mode, without additional frequency bands to use.

In particular, GSM-based mobile telephones should make it possible to have both a GSM connection via a GSM base station, a direct communication to other adapted mobile telephones without a GSM base station, and a simultaneous one

Combination of these types of connections.

As simultaneous connections, in this context, two or more voice or data connections are considered to be useful to the human user in the field

Essentially at the same time. Operation in direct mode is intended to enable communication even when the network fails, for example in case of disaster or when there is no network for other reasons, for example in rural areas or in the case of commercial use, for example by rail workers far from GSM networks. One

Example of application may e.g. be big construction sites where many employees

Communicate with each other, which can cause significant costs in conventional GSM operation. Since the direct mode is not network dependent, should in the

Direct communication no network-dependent costs arise.

These and other objects are achieved by a device having the features of claim 1.

The inventive apparatus utilizes the existing carrier frequencies of a cellular mobile radio system, each carrier frequency transmitting TDMA frames with a TDMA frame duration of 4.615ms and each TDMA frame comprising 8 time slots of 577 microseconds duration. The device is for

Summary of these TDMA frames to a multi-frame comprising 13 TDMA frames with the positions 0 to 12. The device is designed in such a way that the participating terminals in simplex mode always transmit and receive in separate time slots, wherein within each multiframe in each TDMA frame only the first time slot TSO is occupied for transmission or reception, while the other time slots TS1 to TS7 of the TDMA frame remain free. The free time slots TS1 to TS7, if a cellular mobile radio connection is available, can be used for this connection.

According to the invention, the cellular mobile radio connection may in particular, but not exclusively, be GSM, 3G / UMTS, CDMA, 4G / LTE or others

Mobile communications with carrier frequencies in the range of 400MHz to about 2GHz act.

According to the invention, the device is designed as a separate hardware module which controls the direct communication. This has the advantage that the conventional GSM transmission is not affected: the terminals can still send and receive in the GSM system, in the unused time slots of the multiframe. Only single time slots of the GSM transmission frames are used for simplex communication with other terminals. The participating terminals use the GSM transmission frame and build their own synchronized multi-frames with their own synchronization and frequency correction, within which they can communicate with each other in a simplex manner. There must be no new ones

Frequency bands are occupied, and the existing hardware of the GSM terminals can be widely used.

According to the invention, the device can be used both for the simultaneous implementation of cellular mobile communication and direct communication, as well as for the separate implementation of cellular mobile communication or direct communication

be furnished.

According to the invention, the hardware module can be embodied for integration in one of the terminals, in particular for integration into a mobile telephone. The mobile phone can be designed as a smartphone, which is set up for executing a software application (App) for controlling and controlling the hardware module.

In particular, the hardware module may comprise a microphone and a microphone interface for connection to a terminal, a loudspeaker and a loudspeaker interface for connection to the terminal, and a converter circuit for mixing and / or level matching of the audio signals.

According to the invention, the hardware module may comprise a multiplexer for mixing the audio signals of a direct communication connection with the audio signals of a GSM connection. In particular, the device may comprise a separate, preferably connectable to one of the terminals via a USB interface component with a separate speaker and a separate microphone and preferably a separate power supply, wherein the hardware module may be integrated into the component. Instead of the USB interface, any other high-speed digital interface can be provided according to the invention. According to the invention, the separate component can be embodied as an external loudspeaker microphone, which is connected via a USB interface to a terminal,

may preferably be connectable to a mobile phone. According to the invention, a USB-UART converter can be provided for controlling the hardware module.

According to the invention, the separate component can be controlled by a USB codec and a control logic multiplexer for mixing the audio signals of

Direct communication with the audio signals of a GSM connection. The hardware module can comprise a serial interface, preferably a UART interface, and an antenna connection.

According to the invention, the component can include operating elements, preferably a push-to-talk pushbutton and an emergency call button, which can be connected to the hardware module.

According to the invention, it may be provided that the hardware module is designed such that at the position 1 1 of the multiframe in the time slot TSO a frequency correction burst FCCH and at the position 12 of the multiframe in the time slot TSO a

Synchronization Bursts SCH and in the remaining positions of the multiframe in the time slot TSO data bursts TCH are sent.

According to the invention, it can be provided that 158.25 bits are transmitted in each time slot, wherein a data burst TCH comprises a training sequence of 26 bits and two data packets of 57, a synchronization burst SCH a

Training sequence of 64 bits and two data packets of 39 bits each, and the frequency correction burst FCCH comprises 142 bits with the symbol "0".

According to the invention, the hardware module can be designed in such a way that the terminal takes on a repeater function, wherein it is inserted in a first timeslot,

preferably in position TSO, can forward a data packet received in an agreed TDMA frame in a second timeslot, preferably at position TS3, of the same TDMA frame. According to the invention, depending on whether the terminal is the first, second or third repeater, the hardware module can forward the received data packet in different time slots within the agreed TDMA frame, preferably at positions TS3, TS4 and TS5. This prevents a collision of the data packets in overlapping areas between the originally transmitted signal and the signal transmitted by the repeater.

The invention further extends to a mobile terminal, in particular a

Mobile telephone, comprising an integrated device according to the invention, or connected to an external device according to the invention.

Further features of the invention will become apparent from the claims, the description of the figures and the figures.

The invention will be explained in more detail below with reference to non-exclusive embodiments.

1 a shows an exemplary embodiment of a multiframe 3 defined by a device according to the invention, which comprises 26 individual TDMA frames 1. Each TDMA frame 1 comprises eight time slots 2 labeled TS0 to TS7. at

Use of the direct communication is transmitted in the time slots bursts TCH, FCCH and SCH. The abbreviation TCH denotes the Traffic Channel Burst, which contains the voice data to be transmitted. FCCH means Frequency Correction Channel, and SCH is the Synchronization Channel. The frames 1 1 and 24 within the multiframe serve to transmit the

Frequency correction bursts FCCH, and the frames 12 and 25 serve to transmit the synchronization bursts SCH.

In both the direct communication transmission mode and the direct communication reception mode, only the first time slot TSO is allocated for transmission or reception within the multiframe in each TDMA frame, while the other time slots TS1 to TS7 either remain idle or used for the regular GSM connection become. The device according to the invention ensures that the direct communication takes place in simplex mode, so that a mobile terminal in direct mode can only ever either send or receive; without prejudice to a potentially parallel GSM connection.

1 b shows a comparison of the regular GSM frame structure in the TDMA protocol (above) to the frame structure according to the invention (below), wherein only the time slot TSO is shown. In the frame structure according to the invention, the positions 1 1 and 12 within the existing GSM frame are used to transmit SCH and FCH bursts; However, these are when carrying out a

Direct communication connection independent of the synchronization and frequency correction bursts sent by any GSM base station.

In contrast to the GSM connection, the direct communication according to the invention is implemented as "1: N" communication and always runs exclusively in the time slot TSO of the TDMA frames.

The other time slots TS1 to TS7 of the TDMA frames are kept free so that the receivers have sufficient time to process the transmitted data. A dynamic adaptation of the time slots used by the base station or a selected as a "master" terminal is not provided, since the method is to be applied even if there is no contact with the base station.

A dedicated master / slave assignment of the terminals is done by the

not according to the invention. It always transmits only a completely arbitrary terminal, and all other terminals in receive range received (1: N communication). After the end of the transmission can send back any terminal. As a result, no identification of the transmitting or receiving terminals takes place in direct mode. The sent message is always directed to all terminals in the

Reception area, which is particularly advantageous in case of disaster. Fig. 2 shows the structure of a TCH data burst, a SCH synchronization burst and an FCCH frequency correction burst. In a TCH data burst, 1 14 data bits are transmitted, in a SCH synchronization burst, 78 data bits, and in a frequency correction burst, no data bits.

When operating terminals in direct mode, the range is limited by the relatively low transmission power and by terrain influences. The present invention therefore also provides for the possibility that the mobile terminals according to the invention take on a repeater function and, like a relay station, convey the data transmission between two or more other terminals.

Fig. 3 shows the basic situation in the execution of the repeater function. A transmitter transmits data in direct communication to a first repeater. This is still within range of the transmitter, receives the data and sends it within its range. A second repeater, which is within range of the first repeater, receives the data and forwards it in its transmission range. This will create a direct communication between

Allows devices that are not in the same transmission range.

Fig. 4 shows the transmission protocol in the repeater function. Each frame not only works in time slot 1, but also the other time slots come in

Use. The first time slot TS0 is used to receive the transmitted burst. Through the time slot TS3, the signal from the talker and the first repeater is passed. The second repeater receives in time slot 1, designated Rx, and transmits the signal over time slot TS4.

Another repeater would also receive the data in time slot TS0, but forward it in time slot TS5. Also in the repeater function, the transmission is in simplex mode, so that each mobile terminal can only send or receive. Regardless of the repeater function, the terminals can in turn operate a regular GSM communication in the remaining time slots. In the hardware implementation of the device according to the invention, there are basically two possibilities, wherein in both cases the device according to the invention comprises the transmitting and receiving part in the mobile telephone as

Radio interface used.

On the one hand, the device can be integrated into an existing mobile telephone, the microphone and loudspeaker or headphone connection of the mobile telephone being shared for direct communication. In this case, it may be provided that any existing GSM connections with the direct communication are transmitted simultaneously, so that the audio signals of both connections are output at the loudspeaker, and the audio signals recorded via the microphone are forwarded to both connections.

On the other hand, the device can be embodied as an external component, in particular as a remote speaker microphone. In this case, the component has its own speaker and its own microphone. Even in this case, however, it may be provided that any existing GSM connections with the

Direct communication are transmitted simultaneously so that the audio signals of both connections are output at the speaker of the component, and the audio signals recorded via the microphone of the component are forwarded to both connections.

Fig. 5a shows an embodiment of the device according to the invention, wherein the hardware module 4 is connected via an interface 5 to the circuit board 6 of a mobile phone. The installation of the hardware module usually requires an increase in the thickness of the mobile phone of about 4mm.

The hardware module 4 can be designed as a PCB in the form of a leadless chip carrier (LCC) in the dimensions 33mm x 33mm x 3.3mm, which at the

Motherboard of the mobile phone is attached.

In the embodiment of FIG. 5a, the device is integrated into the mobile phone and uses its microphone and speakers to carry out the

Direct communication. The hardware module 4 has to interact with the speaker and microphone of the mobile phone via a microphone interface 7 and a speaker interface 9. About converter circuits 8, 8 ', these interfaces with the corresponding inputs and outputs of the mobile phone circuit board 6 are connected.

The converter circuits 8, 8 'are designed in such a way that the level strength of the GSM connection and the direct communication connection are matched to one another so that both connections can be used even when superposed. This facilitates simultaneous connection via GSM and direct communication.

The hardware module 6 does not have its own power supply in this embodiment, but is connected to the power supply of the mobile telephone circuit board 6. For transmission of the call data, a UART interface 16 is provided with a level adjustment 20, since the hardware module 4 uses a UART voltage of 2.85 V, while on mobile phones usually a

Voltage value of 1, 8V is used for logic components.

5b shows a schematic representation of an embodiment of the converter circuit 8 according to the invention for converting the microphone signals of the mobile telephone circuit board 6 and transmission to the hardware module 4, so that the microphone signals recorded by the mobile phone via the terminals MICP and MICN to the

Hardware module 4 with the connections MIC1 P and MIC1 N and from there to the

Direct communication connection can be passed. In order to prevent the audio signals from being disturbed by the TDMA connection or from picking up noise, it is necessary to execute all the signal lines in the same length and preferably between two grounded plates. In particular the

Signal path 22 should be designed to avoid interference as close as possible to the hardware module 4.

Fig. 5c shows a schematic representation of an embodiment of the converter circuit 8 'according to the invention for the conversion of the loudspeaker signals of the hardware module 4 and transmission to the mobile telephone circuit board 6, so that over the

Direct communication incoming audio signals can be output to the speaker of the mobile phone. In the present embodiment, the hardware module 4 has loudspeaker outputs AUDIOOUT + and AUDIOOUT- and headphone outputs EAR + and EAR-, both of which are fed into the converter circuit 8 '. In order to achieve that both the audio signals of the GSM connection, as well as the

Audio signals of the direct communication on the speaker 12 of the mobile phone

are output, the audio output of the mobile phone is first separated from the loudspeaker amplifier 29 and guided via the illustrated AUXLP and AUXLN connections in the converter circuit 8 '. The loudspeaker amplifier 29 is connected to the output terminals of the converter circuit 8 ', SPKR_SUM_P and

SPKR_SUM_N, connected so that the loudspeaker of the mobile phone

Superposition of the audio signals via AUXLP or AUXLN of the mobile phone, as well as EAR + or EAR and AUDIOOUT + or AUDIOOUT- of the hardware module 4 is output. Again, the converter circuit 8 'must be carefully constructed to avoid interference from TDMA transmission or noise.

6 a shows an alternative embodiment of the device according to the invention as an external component 1 1 which can be connected to a mobile telephone via a USB interface 23 with a separate loudspeaker 12, a separate microphone 13 and a separate power supply in the form of a battery 24, wherein the hardware Module 4 is integrated into the external component 1 1. The component 1 1 can in particular as

Speaker microphone (Remote Speaker Microphone) be executed, which is connectable via the USB interface 23 to the mobile phone.

In this embodiment, there is no mixing of the microphone and

Speaker signals of the GSM connection with the direct communication connection, so that the GSM connection must be routed via the microphone and loudspeaker of the mobile phone.

In this exemplary embodiment, a USB-UART converter 14 is arranged between the UART interface 16 of the hardware module 4 and the USB interface 23.

From the hardware module 4, outputs from a speaker interface 9 lead directly to a dedicated speaker 12 and from a microphone interface 7 directly to a dedicated microphone 13. A converter circuit is not required in this case, since there is no mixing with the microphone and loudspeaker signals of the GSM connection.

Furthermore, a separate antenna connection 17 and an external antenna 21 are provided. There is another USB interface 23 is provided, via which the battery 24 can be charged. Furthermore, located on the component 1 1 a dedicated push-to-talk button 18 and an emergency button 18, which are connected to corresponding inputs on the hardware module 4. To connect the component 1 1 with the

Mobile phone component 1 1 must be configured as a USB slave, and the

Mobile phone as a USB master.

6b shows a further embodiment of the device according to the invention as an external component 1 1 which can be connected to a mobile telephone via a USB interface 23 with a separate loudspeaker 12, a separate microphone 13 and a separate power supply in the form of a battery 24, wherein the hardware Module 4 is integrated into the external component 1 1. The component 1 1 can in particular as

Speaker microphone (Remote Speaker Microphone) be executed, which is connectable via the USB interface 23 to the mobile phone. In this

Embodiment takes place a mixture according to the invention of the microphone and loudspeaker signals of the GSM connection with the direct communication connection via the multiplexer 10, so that in addition to the direct communication connection and a possible GSM connection can be performed simultaneously via microphone 13 and speaker 12 of the component 1 1.

Again, a USB-UART converter 14 is arranged between the UART interface 16 of the hardware module 4 and the USB interface 23. Between the USB interface 23 and the USB-UART converter 14, a USB hub 25 with a first USB interface USB1 and a second USB interface USB2 is arranged so that a further USB interface for a USB codec 15 is available stands.

About this USB codec 15, the transmission of audio signals from the mobile phone to the speaker 12 and from the microphone 13 to the mobile phone. From the hardware module 4 outputs from a loudspeaker interface 9 via a multiplexer 10 to a loudspeaker 12 and from a microphone interface 7 also via the multiplexer 10 to a microphone 13. About the multiplexer 10, which is controlled by a multiplexer drive logic 26, takes place the inventive mixture of the microphone and loudspeaker signals of the direct communication connection with the microphone and loudspeaker signals of the GSM connection. For this purpose, the audio signals of the microphone 13 pass through the multiplexer 10 alternately via the microphone interface 7 to the hardware module 4, where they are transmitted in direct mode, and via the USB codec 15 and the USB hub 25 to the mobile phone, where they over a GSM connection are transmitted. Likewise, the audio signals output from the speaker 12 via the multiplexer 10 are alternately from the GSM connection via USB hub 25 and USB codec 15, as well as from the

Direct communication connection via the loudspeaker interface 9. The USB interface USB2 on the USB hub is responsible for transmitting the data packets to be sent in direct mode to the sender and receiver in the mobile phone.

Mobile phone component 1 1 must be configured as a USB slave, and the

Mobile phone as a USB master; This configuration is supported on Android 4.5+ phones.

The invention is not limited to the present embodiments, but includes all devices within the scope of the following claims. In particular, the invention is not limited to use with a mobile phone or smartphone, but includes use in combination with any mobile terminals that are suitable for making cellular cellular connections. Furthermore, the invention is not limited to the use of GSM, but also includes mobile radio communication over other cellular networks. LIST OF REFERENCE NUMBERS

1 TDMA frame

2 timeslot

3 multi-frames

4 hardware module

5 interface

6 Mobile phone circuit board

7 microphone interface

8, 8 'converter circuit

9 speaker interface

10 multiplexers

1 1 Separate component

12 speakers

13 microphone

14 USB-UART converter

15 USB codec

16 UART interface

17 antenna connection

18 push-to-talk buttons

19 emergency call button

20 level adjustment

21 External antenna

22 signal path

23 USB interface

24 battery

25 USB hub

26 multiplexer drive logic

27 External headphone jack

28 volume control

29 loudspeaker amplifier

Claims

claims

1 . Device for direct communication in simplex mode between mobile

Terminals, in particular mobile telephones (6), using

Carrier frequencies of a cellular mobile radio system, wherein each carrier frequency transmits TDMA frames (1) with a TDMA frame duration of 4.615ms and each TDMA frame comprises 8 time slots (2) with a duration of 577 microseconds,

characterized in that

- The device comprises a hardware module (4), which the

Direct communication controls, where

the device for combining TDMA frames into one

Multi-frame (3) comprising 13 TDMA frames with positions 0 to 12, and

- Is designed so that the participating terminals in simplex mode always in separate time slots (2) send and receive and within each multiframe (3) in each TDMA frame (1) only the first time slot (2) TSO for sending or Receive is occupied while the other time slots (2) TS1 to TS7 of the TDMA frame (1) remain free.

2. Apparatus according to claim 1, characterized in that the device is set up both for the simultaneous implementation of a cellular mobile communication and direct communication, as well as for the separate implementation of a cellular mobile communication or direct communication.

3. Apparatus according to claim 1 or 2, characterized in that the

Hardware module (4) for integration into one of the terminals, in particular for integration into a mobile telephone (6) is executed.

4. Device according to one of claims 1 to 3, characterized in that the hardware module (4) has a microphone and a microphone interface (7) for connection to a terminal, a speaker and a

Speaker interface (9) for connection to the terminal, and a converter circuit (8) for mixing and / or level adjustment of

Includes audio signals.

5. Device according to one of claims 1 to 4, characterized in that the hardware module (4) comprises a multiplexer (10) for mixing the audio signals of a direct communication connection with the audio signals of a GSM connection.

6. Device according to one of claims 1 to 5, characterized in that the device is a separate, with one of the terminals preferably via a USB interface connectable component (1 1) with a separate speaker (12) and a separate microphone (13) and preferably comprises a separate power supply, wherein the hardware module (4) in the component (1 1) is integrated.

7. Apparatus according to claim 6, characterized in that the separate

Component (1 1) is designed as an external speaker microphone, which is connectable via a USB interface with a terminal, preferably a mobile phone (6).

8. The device according to claim 7, characterized in that for driving the hardware module (4), a USB-UART converter (14) is provided.

9. Device according to one of claims 6 to 8, characterized in that the separate component (1 1) by a USB codec (15) and a

Control logic (26) controlled multiplexer (10) for mixing the audio signals of the direct communication with the audio signals of a GSM connection comprises.

10. Device according to one of claims 1 to 9, characterized in that the hardware module (4) comprises a, preferably designed as a UART interface, serial interface (16) and an antenna terminal (17).

1 1. Device according to one of claims 6 to 10, characterized in that the component (1 1) controls, preferably a push-to-talk button (18) and an emergency call button (19), which with the hardware module ( 4) are connected.

12. Device according to one of claims 1 to 1 1, characterized in that the hardware module (4) is designed such that at the position 1 1 of the multiframe (3) a frequency correction burst FCCH and at the position 12 of the multiframe (3) a synchronization burst SCH and in the remaining positions of the multiframe (3) data bursts TCH are sent.

13. Device according to one of claims 1 to 12, characterized in that the hardware module (4) is designed such that the terminal assumes a repeater function, wherein it in a first time slot, preferably in position TS0, an agreed TDMA frame in a second time slot, preferably at position TS3, the same TDMA frame broadcasts received data packet.

14. The device according to claim 13, characterized in that the hardware module (4) depending on whether the terminal of the first, second, or third

Repeater, the received data packet in different time slots within the agreed TDMA frame, preferably at position TS3, TS4 and TS5, broadcasts.

15. Mobile terminal, in particular a mobile telephone, comprising or connected to a device according to one of claims 1 to 14.