WO2008093151A1

WO2008093151A1 - Method of information transfer from the sender to the receiver over voice channel of a cellular communications network

Info

Publication number: WO2008093151A1
Application number: PCT/IB2007/000463
Authority: WO
Inventors: Oleksandr Seredkin
Original assignee: Aktsionerne tovarystvo 'Ohorona i bezpeka'
Priority date: 2007-02-02
Filing date: 2007-02-27
Publication date: 2008-08-07

Abstract

Method of information transfer over voice channel of the mobile communication network includes sending of query by the sender's terminal for connection with the receiver's terminal, verification of the number of the sender's terminal by the receiver and transmission of the message. The receiver controls the duration message transmission, integrity and authenticity of the received message and, in the case of receipt of the integral and reliable message within the predetermined time limit gives a command to terminate the connection by the receiver's terminal. The sender also controls the duration of message transmission and, in the case of receipt of notification about termination of the connection by the receiver's terminal within the predetermined time limit considers the message as passed.

Description

METHOD OF INFORMATION TRANSFER FROM THE SENDER

TO THE RECEIVER OVER VOICE CHANNEL OF A CELLULAR COMMUNICATIONS NETWORK

FIELD OF THE INVENTION

This invention relates to the field of information transfer, for example, reports on the query of access to the systems of information, about the state of account, geographical location of the object, the state of the object, signals of control by objects, emergency and alarm signals etc. over voice channels of cellular communications networks. In particular, this invention relates to intrusion and fire alarm systems where control of the state of the object is carried out by control panels (CP), installed at the protected object, through a cellular communications network, for example, through GSM cellular communications network to Central Monitoring Station (CMS). Control panel (CP) and CMS contain terminals through which communication is carried out. A number of control panels can be connected to one CMS.

BACKGROUND OF THE INVENTION

There are well known methods of information transfer wherein short text messages are sent from the sender terminal, for example, from the terminal of CP, to the terminal of the receiver, for example, CMS, by means of SMS service of a cellular communications network (see RU 2159190, 2000; RU 2216463, 2003; RU 2202484, 2003; RU 2242383, 2004; RU 2291072, 2007 et al). SMS service is described for example, in the GSM standard 04.11 (ETS 300 559): "European digital cellular telecommunications system (Phase 2); Point-to-Point (PP) Short Message Service (SMS) support on mobile radio interface". Low reliability of transmission of messages is a disadvantage of SMS, which is caused by the fact that the same channel is used for transmission of other messages and therefore is often overloaded. As a result the time of message delivery is increased or the message is lost. Besides the provider of SMS services usually charges for transmission of every message separately. In this case when you have many messages the expenses on their transmission might prove to be big enough.

Methods of information transfer over voice channel of a cellular communications networks using Dual Tone Multi-Frequency (DTMF) signals are also known. Thus, according to WO 03/0172117, 2003, a user (sender) sends an query for connection through his terminal to the communication terminal of the (receiver); the terminal of the receiver gets notification about receipt of the above query, the receiver checks up the number of the sender's terminal and, in the case of successful authentication of the sender's terminal number, gives a signal for establishment of connection between the sender's terminal and the terminal of the receiver. Afterwards the sender sends a message to the receiver in the form of DTMF signals. It can be for example, a password for access to a data base or to other services.

The methods of transfer of information of such type are used for securing of access to services of a cellular communications network operator and are highly reliable and protected. At the same time operators of cellular communications networks do not make provision for use of such methods for exchange of information between two subscribers of the network.

It is also known that many operators of cellular communications networks provide their subscribers with a small grace period of time for free connection at the beginning so that if necessary one of the subscribers could cut connection short in case, for example, of false or undesirable connection within the limit of the predetermined grace period of time. Usually duration of such grace period makes from 2 to 6 sec.

SUMMARY OF THE INVENTION

The present invention is directed to create a method of information transfer over voice channel of cellular communications network, which will provide high reliability protection and authenticity of transferred information with the use of DTMF signals of standard service of communication operator.

According to the invention the method of information transfer from the sender to the receiver over voice channel of cellular communications network includes:

sending of a request by sender's terminal for connection with the receiver's terminal,

receiving of notification about the abovementioned query by the receiver's terminal,

verification of the number of sender's terminal by the receiver, establishing of connection between the sender's terminal and that of the receiver, transmission of message through the sender's terminal in form of DTMF signals,

receiving of the message by the receiver's terminal, controlling by the receiver of duration of the message receiving T_RC and checking integrity and authenticity of the received message giving by the receiver's terminal a command for disconnection when integral and authentic message is received within the predetermined time limit T_RO, controlling by the sender of duration of the message transmission T_So Wherein, in the case of receiving a notification about termination of connection by the receiver's terminal within the predetermined time limit T_So the sender considers the message as successfully transmitted, and in the case of non receipt of such a notification within the predetermined time limit T_So gives the command to terminate the connection by the sender's terminal and considers the message as not transmitted. Preferably T_RC >T_So + 1, wherein t - is a time interval between the moment of giving a command to terminate connection by the receiver's terminal and the moment of receipt of the sender's terminal of a notification signal about termination of the connection.

Preferably, T_R0 does not exceed the durations of the grace period of time given by the operator of cellular communications network for free connection.

In the case when the sender considers that the message is not transmitted, it can make another attempt to transfer the message.

For transmission of DTMF signals it is advisable to use standard service by DTMF protocol of cellular communications network.

It is expedient to include into the message a check value of integrity and authenticity thereof; the index of amount of DTMF signals and check sum in the message can serve the purpose.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig.l shows a data flow between CP and CMS at successful transmission of the message.

Fig.2 shows a data flow between CP and CMS when an error of authentication of the number of the sender of the message has occurred.

Fig. 3 shows a data flow between CP and CMS at the message reception error revealed by CMS.

DETAILED DESCRIPTION

The invention is illustrated by an example of use of the method of invention for transfer of information from the control panel (CP) to the Central Monitoring Station (CMS). Fig.l shows an example of data flow between CP and CMS at successful transmission of the message.

In case of occurrence of a monitored event at the protected object, about which the information is supposed to be transmitted to CMS, CP gives a command to the terminal which it is connected to, to send a request for connection over voice channel of a cellular communications network, GSM for example. Terminal CP uses the <ATDxxx;> command, where xxx is a number of the terminal of CMS (receiver of the message) and sends such a quest for connection. The set of standard AT commands is described in the GSM 07.07 standard: "Digital cellular telecommunications system (Phase 2+); AT command set for GSM Mobile Equipment (ME)". CMS checks up the number of sender's terminal using the report of the GSM modem <+clip> and, in the case of successful authentication, establishes connection by the <ATA> command. CP passes a few bytes of the encoded message in the form of DTMF signals, using <AT+VTS> commands. For transmission of one byte two DTMF signals are required. At the end of the message CP passes a check sum. At the moment when connection is established CMS starts the timer waiting for termination of the connection, which counts off the time T_RC during which CMS is on line. CMS receives the message, does the control summing up for verification of integrity and authenticity of the received message and, if the integrity and authenticity of the received message within the predetermined time limit TR_O is confirmed, gives a command for termination of connection by the receiver's terminal. The value of T_R0 is set sufficient for transmission of typical messages. Terminal of CMS terminates connection with the help of the <AT+CHUP> or <ATH> command and terminal CP receives the <NO CARRIER> signal about termination of connection. At the moment when CP receives the signal about establishment of connection, simultaneously it starts the timer to control the timeTsc spent on message transmission and, if the signal about the termination of connection occurred before the expiry of the predetermined time limit of T_So, considers the message as not transmitted. T_R0 is set equal or larger than Tso + t, wherein t - is time of passing of signal about termination of connection to the sender's terminal. If termination of connection happened before the expiry of the given by the operator grace period for free connection, then such transmission is not charged.

Fig.2 shows an example of data flow between CP and CMS when an error of authentication of the sender's terminal number has occurred.

In case of occurrence of a monitored event at the protected object, about which the information is supposed to be transmitted to CMS, CP gives a command to the terminal to which it is connected to send a request for connection over voice channel of the cellular communications network, GSM for example. Terminal of CP uses the <ATDxxx;> command, where xxx is the number of the CMS terminal (receiver of message) and send this request for connection. CMS checks up the number of the sender's terminal using the report of the GSM modem <+clip> and, in the case of error of authentication, gives the command to refuse the connection. The receiver's terminal refuses connection through <AT+CHUP> or <ATH> command, and the terminal of CP gets notification about the connection refusal, on receipt of which CP considers the message as not transmitted and repeats the message transmission procedure in the next session of communication.

Fig. 3 shows an example of data flow between CP and CMS at the message reception error revealed by CMS.

In case of occurrence of a monitored event at the protected object, about which the information is supposed to be transmitted to CMS, CP gives a command to the terminal to which it is connected to send a request for connection over voice channel of the cellular communications network, GSM for example. Terminal of CP uses the <ATDxxx;> command, where xxx - is the number of the CMS terminal (receiver of message) and sends such a request for connection. CMS checks up the number of the sender's terminal using the report of the GSM modem <+clip> and, in case of successful authentication, establishes connection through the <ATA> command. CP sends a set of bytes of the encoded message through DTMF signals using <AT+VTS> commands. For transmission of one byte two DTMF signals are required. At the end of transmission CP sends the check sum. At the moment when connection is established CMS starts the timer, which counts off the time T_RC during which CMS is on line. CMS receives the message, does the control summing up for verification of integrity and authenticity of the received message and, if integrity and authenticity of the received message within the predetermined time limit T_R0 is confirmed, it gives a command for termination of connection by the receiver's terminal. The value of TR₀ is set sufficient for transmission of typical messages. CMS Terminal terminates connection by the <AT+CHUP> or <ATH> command, and CP terminal receives the <NO CARRIER> signal about termination of connection. At the moment when CP receives the signal about establishment of connection it also starts timer to control the time Tsc spent on transmission and, if the signal about termination of connection did not come before the expiry of the predetermined time limit T₈₀, it considers the message as not passed and through the <AT+CHUP> or <ATH> command cancels connection and repeats the message transmission procedure in the next communication session. T_RO is set equal or larger than T_So + t, wherein t - is the signal passing time on termination of connection. If termination of connection happened before the expiry of the given by the operator of the cellular communications network grace period for free connection then, such an attempt of transmission is not charged.

Thus, the invention allows carrying out an integral and reliable transfer of information over voice channel of the cellular communications network. At the same time transmissions of short messages with duration of a few seconds can be done without any charge for such transmissions by the operator of the cellular communications network.

The invention is not limited to the examples described above and relates to all possible applications and modifications accessible to any person skilled in the art.

Claims

1. A method of information transfer from the sender to the receiver over voice channel of a cellular communications network, including sending by the sender's terminal of a query for connection with the receiver's terminal, receiving of notification about said query by the receiver's terminal, verification of the number of sender's terminal by the receiver, establishment of connection between the sender's and receiver's terminals, transmission of messages through the sender's terminal in the form of DTMF signals and receipt of messages by the receiver's terminal, characterized in that the receiver controls the duration of message receiving T_RC as well as the integrity and the authenticity of the received message and, in the case of receipt of the integral and authentic message within the predetermined time limit T_R0 gives a command to terminate the connection by the receiver's terminal; the sender also controls the duration of transmission of the message T_Sc and, in the case of receipt of notification about termination of the connection by the receiver's terminal within the predetermined time limit Tso considers the message as passed, or, in the case of non receipt of such a notification within the predetermined time limit gives a command to terminate the connection by the sender's terminal and considers the message as not passed.

2. The method of Claim 1, characterized in that T_RC ≥T_So + t, wherein t - is the interval of time between the moment of giving the command to terminate the connection by the receiver's terminal and the moment of receiving of notification about termination of the connection by the sender.

3. The method of Claim 1, characterized in that the sender repeats the attempt of transmission if the message is considered as that not passed.

4. The method of Claim 1, characterized in that standard service of DTMF protocol of the cellular communications network is used for transmission of DTMF signals.

5. The method of Claim 1, characterized in that the message includes a check value of integrity and authenticity thereof.

6. The method of Claim 5, characterized in that check value of integrity and authenticity of the message is the index of amount of DTMF signals in the message.

7. The method of Claim 5, characterized in that check value of integrity and authenticity of the message is a check sum.