Title of Invention	"METHOD FOR TRANSMITTING CALLER INFORMATION IN CALLER IDENTIFICATION DELIVERY SERVICE OF A DIGITAL COMMUNICATION SYSTEM"
Abstract	A method for transmitting caller information according to the present invention is characterized in that caller information is divided in bit units, inserted into a certain bit of PCM data, and transmitted with the PCM data to a called party 5 through a traffic channel. In addition, a mobile communication system for realizing the method for transmitting caller information is constructed same as the conventional art. Because the present invention does not require caller information transmission/reception signalling or complex detecting algorithm, the vocoder can be realized on one DSP chip with an echo canceller, etc. Also, the present 10 invention can be applied simply and effectively to a system(e.g. WLL system) which does not support caller information transmission/reception signalling, since the vocoder performs caller information transmission/reception signalling through the signalling channel.

Title of Invention

"METHOD FOR TRANSMITTING CALLER INFORMATION IN CALLER IDENTIFICATION DELIVERY SERVICE OF A DIGITAL COMMUNICATION SYSTEM"

Abstract

A method for transmitting caller information according to the present invention is characterized in that caller information is divided in bit units, inserted into a certain bit of PCM data, and transmitted with the PCM data to a called party 5 through a traffic channel. In addition, a mobile communication system for realizing the method for transmitting caller information is constructed same as the conventional art. Because the present invention does not require caller information transmission/reception signalling or complex detecting algorithm, the vocoder can be realized on one DSP chip with an echo canceller, etc. Also, the present 10 invention can be applied simply and effectively to a system(e.g. WLL system) which does not support caller information transmission/reception signalling, since the vocoder performs caller information transmission/reception signalling through the signalling channel.

Full Text	BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a method for transmitting caller information in caller identification delivery service of a digital communication system, and more particularly it relates to a method for transmitting a caller information. A structure of a general mobile communication system will be described hereinafter with reference to Figure 1 of the accompanying drawings. 2 The conventional method for transmitting caller information has complex signalling procedures, and the complex signalling procedures between the call processing devices are burdens for the respective devices. Also, in order to provide CID service in a system in which the exchange does not support caller information transmission / reception signalling as in the WLL system, the calling party should modulate caller information and transmits the modulated signal through the traffic channel and the called party should comprise an additional vocoder having a function for detecting the caller ingormation. That is, caller information detecting algorithm needs a lot of calculation amount and memories, and therefore, it is difficult to realize the vocoder including caller information detecting algorithm on a DSP chip with an echo canceller, etc.. Also, in the WLL system, the PCM data can not be transmitted for a predetermined time at early stage of speech path setting (about 3 seconds), and the speech tone quality is reduced by a caller information transmission signal in case of a conference call. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for transmitting caller information which inserts caller information into a certain bit of PCM data transmitted through a traffic channel and transmits the PCM data. 3 Accordingly, the present invention provides a method for trasmitting caller information in caller identification delivery service of a digital communication system, said method comprising: dividing caller information into bit unit; inserting the divided information into a certain bit of PCM data; and transmitting the PCM data to a called party through a traffic channel. To achieve the object of the present invention, as embodied and broadly /also described herein, there is/provided a method for transmitting caller information comprising: a step of dividing caller information into bit units, and inserting the divided information into a certain bit of PCM data (S20 and S30); a step of transmitting the PCM data in which the caller information is inserted to a called party (S40); a step of extracting and restoring the caller number information from the PCM data transmitted to the called party (S50); and a step of transmitting the restored caller information to a higher processor (S60). The step of restoring the caller number information(S50) comprises: a step of searching whether a start message exists in the transmitted PCM data (S120); a step of extracting the certain bits of the PCM data until an end message is detected (S130); and a step of restoring the caller number information by combining the extracted data bits in byte units, when the end message is detected (S140). The step of searching for the start message (S120) comprises: a step of extracting the information bit from the certain bits of the transmitted PCM data(S122, not shown); and a step of checking whether there is a same bit pattern 4 as that of the start message by arranging the extracted data bits in order (S124, not shown). The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings: Figure 1 is a block diagram showing a general mobile communication system; Figure 2 is a flow chart showing a process of transmitting caller information according to the present invention; Figure 3 is a flow chart showing a process of restoring caller information according to the present invention; Figure 4 is a conceptual view illustrating transmission of caller information according to the present invention; Figure 5 is an exemplary view showing a start message structure; and Figure 6 is an exemplary view showing an end message structure. 5 Figure 1 is a view showing a structure of general mobile communication system, describing a channel connection between a mobile switching center 110 and a base station center 120 in detail. As shown therein, the general mobile communication system comprises a mobile switching center 110, a base station center (BSC) 120, a base station 130, and a plurality of terminals 140. One side of the BSC 120 is connected to the mobile switching center 110 through a signalling channel and a traffic channel, and the other side of the BSC 120 is connected to the base station 130. The BSC 120 comprises a call control processor (CCP) 121 which is connected to the mobile switching center 110 through the signalling channel, and a vocoder 122 which is connected to the mobile switching center 110 through the traffic channel. The vocoder 122 only extracts, transmits, and reproduces voice characteristics, and therefore, amount of transmitting information(amount of pulse code modulation (PCM) information) can be reduced greatly. That is, the vocoder generally performs an encoding function that compresses PCM data of 64Kbps to 6 be 8Kbps - 13Kbps and makes packet data, and a decoding function that restores the PCM data from the compressed packet data. Also, the vocoder 122 has a function for receiving and detecting caller identification information(termed as 'caller information', hereinafter) besides the encoding function, the decoding function, and a function for matching the packet data and the PCM data. The vocoder 122 is one of essential devices in the mobile communication system. c . _, . . -. /.(Caller Identification Delivery) Presently, most of the mobile communication systems providing CID /_ service transmit/receive caller information through the signalling channel connected between the CCP 121 and the mobile switching center 110. CID service provided by the general mobile communication system will be described as follows. The mobile switching center 110 transmits caller information to the CCP 121 included in the BSC 120 through the signalling channel at an early stage of a speech path setting, and the CCP 121 transmits the received caller information to the mobile terminal 140 through the base station 130. Also, the reversed processes of the above processes are also performed through the signalling channel. Message format and signalling procedure for CID service are realized by international standard, and are variable according to service providers. If signalling procedure for CID service is not coincided between the call processors, or calf processor such as the exchange of wireless local loop (WLL) does not support caller information transmission/reception signalling performed through the signalling channel, CID service can not be made. Therefore, in order to provide CID service, some exchanges of WLL 7 system modulate caller information in frequency shift keying (FSK) method or transform caller information to be dual tone multi frequency (DTMF) form, and then, transmits the modulated (transformed) signal to the vocoder through the traffic channel (PCM data line) for a predetermined time (about 3 seconds) at early stage of speech path setting. The vocoder 122 searches the received PCM data whether there is the FSK signal or DTMF signal of appointed form with the mobile switching center 110, and when the appointed form signal is detected, the vocoder 122 extracts caller information by analyzing the detected signal. In addition, the vocoder 122 transmits the extracted caller information to CCP, that is, a higher processor. Then, the CCP transmits the caller information to the mobile terminal 140 through the base station 130. Cp/ 8 A preferred embodiment of the present invention will be now described with reference to the attached drawings. A method for transmitting caller information according to the present invention is characterized in that caller information is divided into bit units, inserted into a certain bit of PCM data, and transmitted with the PCM data to a called party through a traffic channel. In addition, a mobile communication system for realizing the method according to the present invention is constructed same as that of Figure 1. Figure 2 is a flow chart showing a process of transmitting caller information according to the present invention. As shown therein, the method for transmitting caller information according to the present invention comprises: a step of dividing caller information into bit units, and inserting the divided information into a certain bit of PCM data (S20 and S30); a step of transmitting the PCM data in which the caller information is inserted to a called party (S40); a step of extracting and restoring the caller number information from the PCM data transmitted to the called party (S50); and a step of transmitting the restored caller information to a higher processor (S60). The steps of transmitting caller information (S20-S60) are performed by a vocoder of a base station controller on calling and called party. The process of transmitting caller information according to the present invention will be described in more detail as follows. When a traffic channel is set between a calling terminal and a called terminal, a vocoder 122 is operated. And when the vocoder 122 is operated, a call control processor (CCP) 121 commands the vocoder 122 to transmit caller information. The vocoder 122 starts to transmit the caller information through the traffic channel (PCM data line). Figure 4 is a conceptual view illustrating caller information transmission according to the present invention. As shown therein, the caller information comprises a start message (16 bits), caller's phone number information (88 bits), and an end message (16 bits). The vocoder 122 divides the caller's phone number(termed as "caller number", hereinafter) into bit units, and inserts the divided information into a certain bit of the PCM data. The "insertion" means putting the divided information on the certain bit. That is, the vocoder 122 replaces respective certain bit values of the PCM data with the divided caller number bits. The caller number divided into the bit units are inputted into the lowest bit of a sample on multiples of 20, and original bit on that location is discarded. It takes about 20ms to transmit the information of 8 bits. Of course, the insertion interval(or insertion gap) of the caller information bit suggested in the embodiment does not affect greatly to the speech tone quality. The insertion interval can be adjusted considering the speech tone quality. The length of start message is 16 bits (necessary time 40ms), the length of caller number information is 88 bits (necessary time 220ms), and the length of end message is 16 bits (necessary time 40ms). Therefore, it takes about 0.3 second to transmit the entire caller information (120 bits). The above time is much shorter than the necessary time for transmitting caller information (about 1 second) in the general WLL system. In addition, the discarded bit is only one bit per 160 bits, and therefore, it does not affect to the speech tone quality. The above sample is a signal value of 8 bits size constituting of the PCM data. In order to transform an analog voice signal into a digital signal, the analog signal, that is, continuous time signal should be changed into a discrete time signal. Values of the continuous time signal are extracted in every predetermined time intervals to change them into the discrete time signals. At that time, the respective extracted signal value is called as a sample. Referring to Figures 4 and 5, structures and functions of the start message, caller number information, and the end message will be described as follows. 1) start message Figure 5 is an exemplary view showing a start message structure. The start message is transmitted for the purpose of notifying the start of the caller number information and synchronizing. The vocoder 122 transmits the start message after dividing the start message into bit units and inserting the bit into the lowest bit of a sample on multiples of 20. As shown in Figure 5A, the start message may comprise only a header data (Format A), or may comprise the header data and length information of caller number (Format B). The header data is the combination of bit patterns having low probability to exist in PCM data. In case that the start message is the format A structure, 2 bytes is enough length. However, if the start message is format B structure, the length may be longer than 2 bytes. 2) caller number information When all of the start message bits are transmitted, the vocoder 122 transmits the caller number information according to the transmission procedures. The transmission procedures of the caller number information are same as those of the start message. General phone number (caller number) can be represented in numbers of 11 figures, and the respective number of the phone number is represented in 8 bits (1 byte). Therefore, the length of the caller number information is generally 11 bytes (necessary time 220ms), however, the above length is not fixed. The vocoder 122 transmits the caller number information received from the CCP 121 to the called party, the called party recognizes the information received between the start message and the end message as the caller number information, and therefore, the caller number information has actually no limit in length. However, if the start message is format B structure, the length of the caller number information probably coincided with the caller number length information value included in the start message. 3) end message Figure 6 is an exemplary view showing an end message structure. When the transmission of caller number information is completed, the vocoder 122 transmits the end message to the called party for the purpose of notifying the end of the caller number information. The transmitting procedures of the end message are same as those of the start message. As shown in Figure 6, the end message may comprise only a tail data (Format C), or may comprise the tail data and an error detecting code (Format D). The tail data is the combination of bit patterns having low probability to exist in the PCM data. 12 In case that the end message has the format C structure, 2 bytes is enough length. However, if the end message is format D structure, the length may be longer than 2 bytes. It is advantageous for ensuring reliability of caller number information that the length of tail data is reduced and the length of error detecting code in the end message is increased. The tail data may use the pattern of header data. Figure 3 is a flow chart showing processes for restoring caller information according to the present invention, illustrating a process of extracting caller information from the PCM data and restoring the caller information by the vocoder (S50). At that time, the above vocoder may be the vocoder (not shown) of the base station controller on the called party, and may be the vocoder 122 in receiving status. As shown in Figure 3, the process of the restoring caller information (S50) according to the present invention comprises a step of searching whether a start message exists in the transmitted PCM data (S120); a step of extracting the certain bits of the PCM data until an end message is detected (S130); and a step of restoring the caller number information by combining the extracted data bits in byte units, when the end message is detected (S140). The step of searching for the start message (S120) comprises: a step of extracting the information bit from the certain bits of the transmitted PCM data(S122, not shown); and a step of checking whether there is a same bit pattern as that of the start message by arranging the extracted data bits in order (S124, not shown). The process of restoring caller number information(S50) will be described in more detail as follows. 13 Figure 3 is showing processes of extracting and restoring the caller number information from the PCM data by the above vocoder 122 or the vocoder (not shown) of the base station controller on the called party. At that time, it is assumed that the start message is format B structure of 2 bytes, and the end message is format D structure of 2 bytes. In addition, the process for the caller number length information or for the error detecting code should be pre-appointed between the calling and called party. When the traffic channel is set between the calling terminal and the called terminal, the vocoder 122 searches the PCM data received through the traffic channel (PCM data line) to search for the start message (S110 and S120). That is, the vocoder 122 extracts a certain bit (the lowest bit in a sample on multiple of 20) from the PCM data (S122), and checks whether or not there is a bit pattern coincided with the header data in the start message from a bit row in which the extracted data bits are arranged in order (S124). The extraction of certain bits is repeated until the end message is detected. When the header data is detected, the vocoder 122 restores the caller number length information by combining data bits corresponding to the caller number length information of the start message among the extracted data bits. When the start message (header data and caller number length information) is all extracted, the vocoder 122 restores the caller number information by combining extracted data bits in byte unit until the bit pattern coincided with the tail data of the end message is detected. When the tail data is detected, the vocoder 122 completes the restoration of caller number information, and restores the error detecting code by combining data bits corresponding to the error detecting code of the end message among the 14 data bits extracted after the tail data. Through the above processes, when the caller information (start message, caller number information, and end message) is all detected, the vocoder 122 identifies whether there is an error in the restored caller number information referring to the restored caller number length information and the error detecting code. If there is an error in the caller number information, the vocoder 122 is able to discard the restored caller number information and to request retransmission. However, an additional data form for re-transmitting is needed, and complex procedures and much time are required. Therefore, the present invention notifies that there is an error in the caller number instead of requesting re-transmission to the calling terminal, if it is decided that there is an error in the restored caller number information. However, if there is not an error in the restored caller number information, the vocoder 122 transmits the restored caller number information to CCP. In case that the start message is format A structure of 2 bytes and the end message is format C structure of 2 bytes, the process of restoring caller information is simplified. When the header data is detected in same method as that of step S122 and S124, the vocoder 122 restores the caller number information by combining data bits extracted until the tail data is detected. In addition, the vocoder 122 transmits the restored caller number information to CCP. At that time, the start message and the end message comprise the header data and the tail data respectively, therefore, the vocoder 122 does not perform 15 error checking or re-transmission. As described above, the method for transmitting caller information according to the present invention transmits the caller information as included in some data bits of the PCM data, since the speech tone quality is not affected greatly although some bits of the PCM data is discarded. Therefore, according to the method for transmitting caller information of the present invention, the vocoder can be realized on one DSP chip with an echo canceller, etc., because the present invention does not require caller information transmission/reception signalling or complex detecting algorithm. Also, if the traffic channel is set, caller information can be transmitted at any time. In addition, the present invention does not reduce the speech tone quality, and therefore, the call is not interrupted. Especially, the present invention can be applied simply and effectively to a system(e.g. WLL system) which does not support caller information transmission/reception signalling, since the vocoder performs caller information transmission/reception signalling through the signalling channel. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims. 16 WE CLAIM: 1. A method for trasmitting caller information in caller identification delivery service of a digital communication system, said method comprising: dividing caller information into bit unit; inserting the divided information into a certain bit of PCM data; and transmitting the PCM data to a called party through a traffic channel. 2. The method as claimed in claim 1, wherein the step of transmitting caller information is performed by a vocoder in a base station controller. /as claimed in 3. The method £_claim 1, wherein the certain bit of the PCM data is the lowest bit of a sample which is multiple of 20. 4. The method as claimed in claim 1, wherein the caller information comprises a start message, caller number information, and an end message. 5. The method as claimed in claim 4, wherein the start message comprises a header data field, and a length information field of the caller number. 6. The method as claimed in claim 5, wherein the header data is combination of bit patterns having low probability to exist in the PCM data. 7. The method as claimed in claim 4, wherein the end message comprises a tail data, and an error detecting code. 8. The method as claimed in claim 7, , wherein the tail data is combination of bit patterns having low probability to exist in the PCM data. 9. In caller Identification delivery service of a digital communication system, a method for transmitting caller information comprising: a step of dividing caller information into bit units and inserting the divided information into a certain bit of PCM data; a step of transmitting the PCM data in which the caller information is inserted to a called party; a step of extracting and restoring the caller number information from the PCM data transmitted to the called party; and a step of transmitting the restored caller information to a higher processor. 10. The method as claimed in claim 9, wherein the step of restoring the caller number information comprises: a step of searching whether a start message exists in the transmitted PCM data; a step of extracting the certain bits of the PCM data until an end message is detected, if the start message exists; and a step of restoring the caller number information by combining the extracted data bits in byte units, when the end message is detected. 11. The method as claimed in claim 10, wherein the step of searching for start message comprises: a step of extracting the information bit from the certain bits of the transmitted PCM data; and a step of checking whether there is a same bit pattern as that of the start message by arranging the extracted data bits in order. 12. The method as claimed in claim 9, wherein the step of transmitting caller information further comprises a step of identifying whether there is an error in the restored caller number information, transmitting the restored caller number information to a higher processor if there is not an error, and notifying a calling terminal of the error in caller number without requesting re-transmission if there is an error. 13. The method as claimed in claim 9, wherein the step of transmitting caller information is performed by the vocoder of a base station controller on calling and called party. 14. The method as claimed in claim 9, wherein the certain bit of the PCM data is the lowest bit of a sample which is multiple of 20. 15. In caller Identification delivery service of a digital communication system, a method for transmitting caller information comprising: a step of dividing caller information into bit units and inserting the divided caller information into a certain bit of PCM data; a step of transmitting the PCM data in which the caller information is inserted to a called party; 19 a step of detecting a start message from the PCM data, when the PCM data is transmitted to the called party; a step of extracting certain bits of the PCM data until an end message is detected, when the start message is detected; a step of restoring the caller number information by combining the extracted data bits in byte unit, when the end message is detected; and a step of transmitting the restored caller number information Jo a higher processor. 16. The method as claimed in claim 15, wherein the step of detecting start message comprises: a step of extracting the information bit from the certain bits of the transmitted PCM data; and a step of checking whether there is a bit pattern same as that of the start message by arranging the extracted data bits in order. 17. A method for transmitting caller information, substantially as herein described, particularly with reference to the accompanying drawings. A method for transmitting caller information according to the present invention is characterized in that caller information is divided in bit units, inserted into a certain bit of PCM data, and transmitted with the PCM data to a called party 5 through a traffic channel. In addition, a mobile communication system for realizing the method for transmitting caller information is constructed same as the conventional art. Because the present invention does not require caller information transmission/reception signalling or complex detecting algorithm, the vocoder can be realized on one DSP chip with an echo canceller, etc. Also, the present 10 invention can be applied simply and effectively to a system(e.g. WLL system) which does not support caller information transmission/reception signalling, since the vocoder performs caller information transmission/reception signalling through the signalling channel.

Full Text

BACKGROUND OF THE INVENTION Field of the Invention
The present invention relates to a method for transmitting caller information in caller identification delivery service of a digital communication system, and more particularly it relates to a method for transmitting a caller information.
A structure of a general mobile communication system will be described hereinafter with reference to Figure 1 of the accompanying drawings.
2

The conventional method for transmitting caller information has complex signalling procedures, and the complex signalling procedures between the call processing devices are burdens for the respective devices.
Also, in order to provide CID service in a system in which the exchange does not support caller information transmission / reception signalling as in the WLL system, the calling party should modulate caller information and transmits the modulated signal through the traffic channel and the called party should comprise an additional vocoder having a function for detecting the caller ingormation.
That is, caller information detecting algorithm needs a lot of calculation amount and memories, and therefore, it is difficult to realize the vocoder including caller information detecting algorithm on a DSP chip with an echo canceller, etc..
Also, in the WLL system, the PCM data can not be transmitted for a predetermined time at early stage of speech path setting (about 3 seconds), and
the speech tone quality is reduced by a caller information transmission signal in case of a conference call.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a method for transmitting caller information which inserts caller information into a certain bit of PCM data transmitted through a traffic channel and transmits the PCM data.
3

Accordingly, the present invention provides a method for trasmitting caller information in caller identification delivery service of a digital communication system, said method comprising:
dividing caller information into bit unit;
inserting the divided information into a certain bit of PCM data; and
transmitting the PCM data to a called party through a traffic channel.
To achieve the object of the present invention, as embodied and broadly
/also described herein, there is/provided a method for transmitting caller information
comprising: a step of dividing caller information into bit units, and inserting the divided information into a certain bit of PCM data (S20 and S30); a step of transmitting the PCM data in which the caller information is inserted to a called party (S40); a step of extracting and restoring the caller number information from the PCM data transmitted to the called party (S50); and a step of transmitting the restored caller information to a higher processor (S60).
The step of restoring the caller number information(S50) comprises: a step of searching whether a start message exists in the transmitted PCM data (S120); a step of extracting the certain bits of the PCM data until an end message is detected (S130); and a step of restoring the caller number information by combining the extracted data bits in byte units, when the end message is detected (S140).
The step of searching for the start message (S120) comprises: a step of extracting the information bit from the certain bits of the transmitted PCM data(S122, not shown); and a step of checking whether there is a same bit pattern
4

as that of the start message by arranging the extracted data bits in order (S124, not shown).
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:
Figure 1 is a block diagram showing a general mobile communication system;
Figure 2 is a flow chart showing a process of transmitting caller information according to the present invention;
Figure 3 is a flow chart showing a process of restoring caller information according to the present invention;
Figure 4 is a conceptual view illustrating transmission of caller information according to the present invention;
Figure 5 is an exemplary view showing a start message structure; and
Figure 6 is an exemplary view showing an end message structure.
5

Figure 1 is a view showing a structure of general mobile communication system, describing a channel connection between a mobile switching center 110 and a base station center 120 in detail.
As shown therein, the general mobile communication system comprises a mobile switching center 110, a base station center (BSC) 120, a base station 130, and a plurality of terminals 140. One side of the BSC 120 is connected to the mobile switching center 110 through a signalling channel and a traffic channel, and the other side of the BSC 120 is connected to the base station 130.
The BSC 120 comprises a call control processor (CCP) 121 which is connected to the mobile switching center 110 through the signalling channel, and a vocoder 122 which is connected to the mobile switching center 110 through the traffic channel.
The vocoder 122 only extracts, transmits, and reproduces voice characteristics, and therefore, amount of transmitting information(amount of pulse code modulation (PCM) information) can be reduced greatly. That is, the vocoder generally performs an encoding function that compresses PCM data of 64Kbps to
6

be 8Kbps - 13Kbps and makes packet data, and a decoding function that restores the PCM data from the compressed packet data.
Also, the vocoder 122 has a function for receiving and detecting caller
identification information(termed as 'caller information', hereinafter) besides the
encoding function, the decoding function, and a function for matching the packet
data and the PCM data. The vocoder 122 is one of essential devices in the mobile
communication system. c . _, . . -.
/.(Caller Identification Delivery) Presently, most of the mobile communication systems providing CID /_
service transmit/receive caller information through the signalling channel connected between the CCP 121 and the mobile switching center 110. CID service provided by the general mobile communication system will be described as follows.
The mobile switching center 110 transmits caller information to the CCP 121 included in the BSC 120 through the signalling channel at an early stage of a speech path setting, and the CCP 121 transmits the received caller information to the mobile terminal 140 through the base station 130. Also, the reversed processes of the above processes are also performed through the signalling channel.
Message format and signalling procedure for CID service are realized by international standard, and are variable according to service providers. If signalling procedure for CID service is not coincided between the call processors, or calf processor such as the exchange of wireless local loop (WLL) does not support caller information transmission/reception signalling performed through the signalling channel, CID service can not be made.
Therefore, in order to provide CID service, some exchanges of WLL
7

system modulate caller information in frequency shift keying (FSK) method or transform caller information to be dual tone multi frequency (DTMF) form, and then, transmits the modulated (transformed) signal to the vocoder through the traffic channel (PCM data line) for a predetermined time (about 3 seconds) at early stage of speech path setting.
The vocoder 122 searches the received PCM data whether there is the FSK signal or DTMF signal of appointed form with the mobile switching center 110, and when the appointed form signal is detected, the vocoder 122 extracts caller information by analyzing the detected signal. In addition, the vocoder 122 transmits the extracted caller information to CCP, that is, a higher processor. Then, the CCP transmits the caller information to the mobile terminal 140 through the base station 130.
Cp/
8

A preferred embodiment of the present invention will be now described with reference to the attached drawings.
A method for transmitting caller information according to the present invention is characterized in that caller information is divided into bit units, inserted into a certain bit of PCM data, and transmitted with the PCM data to a called party through a traffic channel. In addition, a mobile communication system for realizing the method according to the present invention is constructed same as that of Figure 1.
Figure 2 is a flow chart showing a process of transmitting caller information according to the present invention.
As shown therein, the method for transmitting caller information according to the present invention comprises: a step of dividing caller information into bit units, and inserting the divided information into a certain bit of PCM data (S20 and S30); a step of transmitting the PCM data in which the caller information is inserted to a called party (S40); a step of extracting and restoring the caller number information from the PCM data transmitted to the called party (S50); and a step of transmitting the restored caller information to a higher processor (S60).
The steps of transmitting caller information (S20-S60) are performed by a vocoder of a base station controller on calling and called party.
The process of transmitting caller information according to the present invention will be described in more detail as follows.
When a traffic channel is set between a calling terminal and a called terminal, a vocoder 122 is operated. And when the vocoder 122 is operated, a call

control processor (CCP) 121 commands the vocoder 122 to transmit caller information. The vocoder 122 starts to transmit the caller information through the traffic channel (PCM data line).
Figure 4 is a conceptual view illustrating caller information transmission according to the present invention.
As shown therein, the caller information comprises a start message (16 bits), caller's phone number information (88 bits), and an end message (16 bits).
The vocoder 122 divides the caller's phone number(termed as "caller number", hereinafter) into bit units, and inserts the divided information into a certain bit of the PCM data. The "insertion" means putting the divided information on the certain bit. That is, the vocoder 122 replaces respective certain bit values of the PCM data with the divided caller number bits.
The caller number divided into the bit units are inputted into the lowest bit of a sample on multiples of 20, and original bit on that location is discarded. It takes about 20ms to transmit the information of 8 bits. Of course, the insertion interval(or insertion gap) of the caller information bit suggested in the embodiment does not affect greatly to the speech tone quality. The insertion interval can be adjusted considering the speech tone quality.
The length of start message is 16 bits (necessary time 40ms), the length of caller number information is 88 bits (necessary time 220ms), and the length of end message is 16 bits (necessary time 40ms). Therefore, it takes about 0.3 second to transmit the entire caller information (120 bits). The above time is much shorter than the necessary time for transmitting caller information (about 1 second) in the general WLL system. In addition, the discarded bit is only one bit per 160 bits, and therefore, it does not affect to the speech tone quality.

The above sample is a signal value of 8 bits size constituting of the PCM data.
In order to transform an analog voice signal into a digital signal, the analog signal, that is, continuous time signal should be changed into a discrete time signal. Values of the continuous time signal are extracted in every predetermined time intervals to change them into the discrete time signals. At that time, the respective extracted signal value is called as a sample.
Referring to Figures 4 and 5, structures and functions of the start message, caller number information, and the end message will be described as follows.
1) start message
Figure 5 is an exemplary view showing a start message structure.
The start message is transmitted for the purpose of notifying the start of the caller number information and synchronizing.
The vocoder 122 transmits the start message after dividing the start message into bit units and inserting the bit into the lowest bit of a sample on multiples of 20.
As shown in Figure 5A, the start message may comprise only a header data (Format A), or may comprise the header data and length information of caller number (Format B). The header data is the combination of bit patterns having low probability to exist in PCM data.
In case that the start message is the format A structure, 2 bytes is enough length. However, if the start message is format B structure, the length may be longer than 2 bytes.
2) caller number information
When all of the start message bits are transmitted, the vocoder 122

transmits the caller number information according to the transmission procedures. The transmission procedures of the caller number information are same as those of the start message.
General phone number (caller number) can be represented in numbers of 11 figures, and the respective number of the phone number is represented in 8 bits (1 byte). Therefore, the length of the caller number information is generally 11 bytes (necessary time 220ms), however, the above length is not fixed.
The vocoder 122 transmits the caller number information received from the CCP 121 to the called party, the called party recognizes the information received between the start message and the end message as the caller number information, and therefore, the caller number information has actually no limit in length. However, if the start message is format B structure, the length of the caller number information probably coincided with the caller number length information value included in the start message.
3) end message
Figure 6 is an exemplary view showing an end message structure.
When the transmission of caller number information is completed, the vocoder 122 transmits the end message to the called party for the purpose of notifying the end of the caller number information.
The transmitting procedures of the end message are same as those of the start message.
As shown in Figure 6, the end message may comprise only a tail data (Format C), or may comprise the tail data and an error detecting code (Format D). The tail data is the combination of bit patterns having low probability to exist in the
PCM data.
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In case that the end message has the format C structure, 2 bytes is enough length. However, if the end message is format D structure, the length may be longer than 2 bytes.
It is advantageous for ensuring reliability of caller number information that the length of tail data is reduced and the length of error detecting code in the end message is increased. The tail data may use the pattern of header data.
Figure 3 is a flow chart showing processes for restoring caller information according to the present invention, illustrating a process of extracting caller information from the PCM data and restoring the caller information by the vocoder (S50). At that time, the above vocoder may be the vocoder (not shown) of the base station controller on the called party, and may be the vocoder 122 in receiving status.
As shown in Figure 3, the process of the restoring caller information (S50) according to the present invention comprises a step of searching whether a start message exists in the transmitted PCM data (S120); a step of extracting the certain bits of the PCM data until an end message is detected (S130); and a step of restoring the caller number information by combining the extracted data bits in byte units, when the end message is detected (S140).
The step of searching for the start message (S120) comprises: a step of extracting the information bit from the certain bits of the transmitted PCM data(S122, not shown); and a step of checking whether there is a same bit pattern as that of the start message by arranging the extracted data bits in order (S124, not shown).
The process of restoring caller number information(S50) will be described
in more detail as follows.
13

Figure 3 is showing processes of extracting and restoring the caller number information from the PCM data by the above vocoder 122 or the vocoder (not shown) of the base station controller on the called party. At that time, it is assumed that the start message is format B structure of 2 bytes, and the end message is format D structure of 2 bytes. In addition, the process for the caller number length information or for the error detecting code should be pre-appointed between the calling and called party.
When the traffic channel is set between the calling terminal and the called terminal, the vocoder 122 searches the PCM data received through the traffic channel (PCM data line) to search for the start message (S110 and S120). That is, the vocoder 122 extracts a certain bit (the lowest bit in a sample on multiple of 20) from the PCM data (S122), and checks whether or not there is a bit pattern coincided with the header data in the start message from a bit row in which the extracted data bits are arranged in order (S124). The extraction of certain bits is repeated until the end message is detected.
When the header data is detected, the vocoder 122 restores the caller number length information by combining data bits corresponding to the caller number length information of the start message among the extracted data bits.
When the start message (header data and caller number length information) is all extracted, the vocoder 122 restores the caller number information by combining extracted data bits in byte unit until the bit pattern coincided with the tail data of the end message is detected.
When the tail data is detected, the vocoder 122 completes the restoration of caller number information, and restores the error detecting code by combining data bits corresponding to the error detecting code of the end message among the
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data bits extracted after the tail data.
Through the above processes, when the caller information (start message, caller number information, and end message) is all detected, the vocoder 122 identifies whether there is an error in the restored caller number information referring to the restored caller number length information and the error detecting code.
If there is an error in the caller number information, the vocoder 122 is able to discard the restored caller number information and to request retransmission. However, an additional data form for re-transmitting is needed, and complex procedures and much time are required.
Therefore, the present invention notifies that there is an error in the caller number instead of requesting re-transmission to the calling terminal, if it is decided that there is an error in the restored caller number information.
However, if there is not an error in the restored caller number information, the vocoder 122 transmits the restored caller number information to CCP.
In case that the start message is format A structure of 2 bytes and the end message is format C structure of 2 bytes, the process of restoring caller information is simplified.
When the header data is detected in same method as that of step S122 and S124, the vocoder 122 restores the caller number information by combining data bits extracted until the tail data is detected. In addition, the vocoder 122 transmits the restored caller number information to CCP.
At that time, the start message and the end message comprise the header data and the tail data respectively, therefore, the vocoder 122 does not perform
15

error checking or re-transmission.
As described above, the method for transmitting caller information according to the present invention transmits the caller information as included in some data bits of the PCM data, since the speech tone quality is not affected greatly although some bits of the PCM data is discarded.
Therefore, according to the method for transmitting caller information of the present invention, the vocoder can be realized on one DSP chip with an echo canceller, etc., because the present invention does not require caller information transmission/reception signalling or complex detecting algorithm.
Also, if the traffic channel is set, caller information can be transmitted at any time. In addition, the present invention does not reduce the speech tone quality, and therefore, the call is not interrupted.
Especially, the present invention can be applied simply and effectively to a system(e.g. WLL system) which does not support caller information transmission/reception signalling, since the vocoder performs caller information transmission/reception signalling through the signalling channel.
As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.
16

WE CLAIM:
1. A method for trasmitting caller information in caller identification delivery
service of a digital communication system, said method comprising:
dividing caller information into bit unit;
inserting the divided information into a certain bit of PCM data; and
transmitting the PCM data to a called party through a traffic channel.
2. The method as claimed in claim 1, wherein the step of transmitting caller
information is performed by a vocoder in a base station controller.
/as claimed in
3. The method £_claim 1, wherein the certain bit of the PCM data is the lowest bit of a sample which is multiple of 20.
4. The method as claimed in claim 1, wherein the caller information comprises a start message, caller number information, and an end message.
5. The method as claimed in claim 4, wherein the start message comprises a header data field, and a length information field of the caller number.
6. The method as claimed in claim 5, wherein the header data is combination of bit patterns having low probability to exist in the PCM data.
7. The method as claimed in claim 4, wherein the end message comprises a tail data, and an error detecting code.

8. The method as claimed in claim 7, , wherein the tail data is combination of bit patterns having low probability to exist in the PCM data.
9. In caller Identification delivery service of a digital communication
system, a method for transmitting caller information comprising:
a step of dividing caller information into bit units and inserting the divided information into a certain bit of PCM data;
a step of transmitting the PCM data in which the caller information is inserted to a called party;
a step of extracting and restoring the caller number information from the PCM data transmitted to the called party; and
a step of transmitting the restored caller information to a higher processor.
10. The method as claimed in claim 9, wherein the step of restoring the caller
number information comprises:
a step of searching whether a start message exists in the transmitted PCM data;
a step of extracting the certain bits of the PCM data until an end message is detected, if the start message exists; and
a step of restoring the caller number information by combining the extracted data bits in byte units, when the end message is detected.
11. The method as claimed in claim 10, wherein the step of searching for start
message comprises:

a step of extracting the information bit from the certain bits of the transmitted PCM data; and
a step of checking whether there is a same bit pattern as that of the start message by arranging the extracted data bits in order.
12. The method as claimed in claim 9, wherein the step of transmitting caller information further comprises a step of identifying whether there is an error in the restored caller number information, transmitting the restored caller number information to a higher processor if there is not an error, and notifying a calling terminal of the error in caller number without requesting re-transmission if there is an error.
13. The method as claimed in claim 9, wherein the step of transmitting caller information is performed by the vocoder of a base station controller on calling and called party.
14. The method as claimed in claim 9, wherein the certain bit of the PCM data is the lowest bit of a sample which is multiple of 20.
15. In caller Identification delivery service of a digital communication system, a method for transmitting caller information comprising:
a step of dividing caller information into bit units and inserting the divided caller information into a certain bit of PCM data;
a step of transmitting the PCM data in which the caller information is inserted to a called party;
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a step of detecting a start message from the PCM data, when the PCM data is transmitted to the called party;
a step of extracting certain bits of the PCM data until an end message is detected, when the start message is detected;
a step of restoring the caller number information by combining the extracted data bits in byte unit, when the end message is detected; and
a step of transmitting the restored caller number information Jo a higher processor.
16. The method as claimed in claim 15, wherein the step of detecting start message comprises:
a step of extracting the information bit from the certain bits of the transmitted PCM data; and
a step of checking whether there is a bit pattern same as that of the start message by arranging the extracted data bits in order.
17. A method for transmitting caller information, substantially as herein described, particularly with reference to the accompanying drawings.
A method for transmitting caller information according to the present invention is characterized in that caller information is divided in bit units, inserted into a certain bit of PCM data, and transmitted with the PCM data to a called party 5 through a traffic channel. In addition, a mobile communication system for realizing the method for transmitting caller information is constructed same as the conventional art. Because the present invention does not require caller information transmission/reception signalling or complex detecting algorithm, the vocoder can be realized on one DSP chip with an echo canceller, etc. Also, the present 10 invention can be applied simply and effectively to a system(e.g. WLL system) which does not support caller information transmission/reception signalling, since the vocoder performs caller information transmission/reception signalling through the signalling channel.

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Patent Number

203294

Indian Patent Application Number

455/CAL/2002

PG Journal Number

10/2007

Publication Date

09-Mar-2007

Grant Date

09-Mar-2007

Date of Filing

30-Jul-2002

Name of Patentee

LG ELECTRONICS INC.

Applicant Address

20, YOIDO-DONG, YONGDUNGPO-KU, SEOUL, REPUBLIC OF KOREA.

Inventors:

#	Inventor's Name	Inventor's Address
1	KIM SOON-UK	DONGBU APT. 102-804, SINLIM 1-DONG, GWANAK-GU, SEOUL REPUBLIC OF KOREA

PCT International Classification Number

H 04M 1/57

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	47980/2001	2001-08-09	Republic of Korea