KR102539720B1 - APPARATUS AND METHOD FOR CHANGING A CODEC IN VoLTE Terminal - Google Patents

Abstract

An apparatus and method for changing a codec capable of improving voice call quality by changing a codec during a voice call according to a wireless environment in a terminal using a voice call service are disclosed. According to an aspect, an apparatus for changing a codec according to a wireless environment in a terminal providing a voice call receives a Radio Resource Control (RRC) message from a communication network and stores parameters including a triggering event included in the RRC message in memory. receiving unit to store in; a parameter definition unit for defining codec change parameters by referring to the parameters stored in the memory and storing them in the memory; When the triggering event occurs during the voice call, an MR message transmission unit for transmitting an MR (Measurement Report) message of the collected wireless environment information to the communication network; and a codec change determination unit for determining whether to change the codec by referring to the codec change parameters based on transmission of the MR message.

Description

Apparatus and method for changing codec of VoLTE terminal {APPARATUS AND METHOD FOR CHANGING A CODEC IN VoLTE Terminal}

The present invention relates to codec change in a Voice of LTE (VoLTE) service, and more particularly, to an apparatus and method for changing a codec of a VoLTE terminal to a codec negotiated between terminals during communication.

Mobile communication technology standards have evolved into 2nd generation (GSM), 3rd generation (UMTS), and 4th generation (LTE) based on 3GPP. In UMTS (universal mobile telecommunication system), the 3rd generation technical standard, it is divided into CS (Circuit Switching) domain for voice call service and PS (Packet Switching) domain for data service. On the other hand, LTE (Long Term Evolution), the 4th generation technical standard, provides only the PS domain represented by the ALL IP (Internet Protocol) network, and provides voice call service in the form of CSFB (Circuit Switched Fallback) through interworking with the 3G CS domain. are providing As a result, there is a problem in that the complexity and operation cost of the network increase. In order to solve this problem, the LTE network introduces a voice call service through a PS domain (ie, a data communication network), which is VoLTE (Voice over LTE) borrowed from an existing VoIP (Voice of IP) service.

In the VoLTE call processing procedure, when the calling terminal delivers the entire list of codecs supported by the calling terminal to the called terminal through an offer message (INVITE), the called terminal sends a codec list supported by itself among the received codec list through an answer message (200 OK) to the calling terminal using the offer/answer model. However, the negotiation method of transmitting the codec list becomes a factor in increasing the size of a Session Initiation Protocol (SIP) message by exchanging unnecessary codecs. In addition, once codec negotiation proceeds, communication is performed using the initially negotiated codec, and a codec that occupies a high bandwidth must be continuously used even in a situation where the wireless environment deteriorates, and there is a problem in that there is no method for renegotiating the codec.

Republic of Korea Patent Publication, No. 10-2016-0122239, "Low Power Low Latency Protocol for Data Exchange"

The present invention has been proposed to solve the above-described problems, and provides a codec changing apparatus and method capable of improving voice call quality by changing the codec during a voice call according to a wireless environment in a terminal using a voice call service. there is

According to an aspect, an apparatus for changing a codec according to a wireless environment in a terminal providing a voice call receives a Radio Resource Control (RRC) message from a communication network and stores parameters including a triggering event included in the RRC message in memory. receiving unit to store in; a parameter definition unit for defining codec change parameters with reference to the parameters stored in the memory and storing them in the memory; When the triggering event occurs during the voice call, an MR (Measurement Report) message including collected wireless environment information is transmitted to the communication network; and a codec change determining unit that determines whether or not to change the codec by referring to the transmission of the MR message and the codec change parameter.

The parameter definition unit defines a codec change event as the codec change parameter, and defines at least one of the triggering events as the codec change event, and the codec change determination unit determines that the generated triggering event corresponds to the codec change event. If applicable, it may be determined whether or not the codec is changed.

The parameter definition unit further defines the minimum number of MR message transmissions as the codec change parameter, and the codec change determination unit further compares the number of transmissions of the MR message for the same codec change event with the minimum number of transmissions of the MR message. It can determine whether or not to change the codec.

The parameter definition unit defines a minimum signal level at which a codec can be changed as the codec change parameter, and the codec change determination unit compares the signal strength of a currently accessed cell with the minimum signal level to determine whether to change a codec. .

The codec change determination unit may change the current codec to another codec when the signal strength of the currently accessed cell is less than the minimum signal level.

The current codec is an Enhanced Voice Services (EVS) codec and the other codec is an Adaptive Multi-Rate Wideband (AMR-WB) codec, or the current codec is an AMR-WB codec and the other codec is an Adaptive Multi-Rate Wideband (AMR-NB) codec. narrowband) codec.

The parameter definition unit may define a duration for codec change as the codec change parameter, and the codec change determination unit may drive a timer based on transmission of the MR message and determine whether to change the codec within the duration. .

The codec change determination unit may wait for a handover command without determining whether to change the codec when the signal strength of the currently accessed cell is greater than or equal to the signal strength of the neighboring cell.

A method for changing a codec according to a wireless environment in a terminal providing voice calls according to another aspect includes receiving a Radio Resource Control (RRC) message from a communication network and storing parameters including a triggering event included in the RRC message in memory. storing; defining codec change parameters by referring to the parameters stored in the memory and storing them in the memory; transmitting a Measurement Report (MR) message including collected wireless environment information to the communication network when the triggering event occurs during the voice call; and determining whether to change the codec by referring to the transmission of the MR message and the codec change parameter.

The step of defining and storing the codec change parameter in the memory may include defining a codec change event as the codec change parameter, defining at least one of the triggering events as the codec change event, and the determining step, When the generated triggering event corresponds to the codec change event, it may be determined whether or not the codec is changed.

The step of defining and storing the codec change parameter in the memory further defines the minimum number of MR message transmissions as the codec change parameter, and the determining step includes the number of transmissions of the MR message for the same codec change event and It is possible to determine whether to change the codec by further comparing the minimum number of transmissions of the MR message.

In the step of defining and storing the codec change parameter in the memory, the minimum signal level at which the codec can be changed is defined as the codec change parameter, and in the step of determining, the signal strength of the currently accessed cell and the minimum signal level are defined. By comparing, it is possible to determine whether the codec has been changed.

In the determining step, the current codec may be changed to another codec if the signal strength of the currently accessed cell is less than the minimum signal level.

The current codec is an Enhanced Voice Services (EVS) codec and the other codec is an Adaptive Multi-Rate Wideband (AMR-WB) codec, or the current codec is an AMR-WB codec and the other codec is an Adaptive Multi-Rate Wideband (AMR-NB) codec. narrowband) codec.

In the step of defining and storing the codec change parameter in the memory, a duration for codec change is defined as the codec change parameter, and in the determining step, a timer is driven based on the transmission of the MR message and the duration It is possible to determine whether or not to change the codec within a certain amount of time.

In the step of determining, if the signal strength of the currently accessed cell is equal to or greater than the signal strength of the neighboring cell, the handover command may be waited for without determining whether to change the codec.

According to an embodiment, during a voice call, the terminal can prevent deterioration of voice call quality without affecting the wireless environment by adaptively changing the codec according to the wireless environment.

According to an embodiment, a battery of a terminal may be saved according to a wireless environment by changing a codec during a voice call based on various conditions.

1 is a diagram schematically illustrating a communication system for codec change using an LTE signaling message according to an embodiment.
2 is a block diagram illustrating functions of the mobile terminal of FIG. 1;
3 is a flowchart illustrating a method of changing a codec in a VoLTE terminal according to an embodiment.
4 is a flowchart illustrating an embodiment of the codec change determination step of FIG. 3 .
FIG. 5 is a flowchart illustrating another embodiment of the codec change determination step of FIG. 3 .

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the following examples. This embodiment is provided to more completely explain the present invention to those skilled in the art. In addition, although specific terms have been used in the drawings and specifications of the present invention, they are only used for the purpose of describing the present invention, and are not used to limit the scope of the present invention described in the meaning or claims. Therefore, those of ordinary skill in the art will understand that various modifications and equivalent other embodiments are possible therefrom. Therefore, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims.

Meanwhile, in this specification, singular forms also include plural forms unless otherwise specified in the text. As used herein, “comprises” and/or “comprising” means the presence of one or more other components, steps, operations, and/or elements in the stated component, step, operation, and/or element. or adding

Then, with reference to the drawings, a codec change apparatus and method in a VoLTE terminal according to the present invention will be described in detail.

1 is a diagram schematically illustrating a communication system for codec change using an LTE signaling message according to an embodiment. Referring to FIG. 1 , a communication system may include a base station 10 (eNB) and a mobile terminal 20. According to the LTE standard (3GPP TS 36.331, etc.) established by the 3rd Generation Partnership Project (3GPP), the base station 10 of the communication system transmits a Radio Resource Control (RRC) message (eg, rrcConnectionReconfiguration Message) to the mobile terminal 20 And, the mobile terminal 20 collects radio environment information of the currently accessed base station 10 and neighboring base stations based on events of various conditions included in the received RRC message, and transmits MR to the currently accessed base station 10 ( Yes, MeasurementReport) message. The mobile terminal 20 changes the codec during a voice call using radio environment information collected based on the RRC message received from the base station 10 .

In the embodiment with reference to FIG. 1, the base station 10 connects the mobile terminal 20 to the network, transmits an RRC message (eg, rrcConnectionReconfiguration Message) to the mobile terminal 20, and transmits an MR (eg, MeasurementReport) message. can be triggered. There are various functions of the RRC message transmitted from the base station 10 to the mobile terminal 20, but in this embodiment, the RRC message transmitted from the base station 10 to the mobile terminal 20 is an MR message from the mobile terminal 20 An example of triggering to report is described.

In general, the mobile terminal 20 must perform handover when the signal strength of the currently accessed base station 10 decreases and the signal strength of the neighboring base station relatively increases, and the triggering condition and decision condition for handover are RRC It can be changed by messages and base station internal setting values. To this end, the base station 10 needs to receive radio environment information from the mobile terminal 20 in order to determine whether or not the mobile terminal 20 will perform handover. The base station 10 transmits an LTE frequency channel (EARFCN: EUTRA Absolute Radio Frequency Channel, measConfigID) to be searched to the mobile terminal 20 through an RRC message, a triggering event for transmitting an MR message (eg, reportConfig), and an RF value to be measured ( Yes, parameters such as RSRP, RSRQ value) can be transmitted (step ①). Here, the triggering event for transmitting the MR message is an event for determining under which radio conditions the LTE frequency channel is to be measured. When an event corresponding to the triggering event occurs, the mobile terminal 20 collects and collects surrounding wireless environment information. The radio environment information is transmitted to the base station 10 through an MR message.

The mobile terminal 20 is a terminal using a voice call service through an LTE network. According to one embodiment, the mobile terminal 20 stores the parameters included in the RRC message received from the base station 10 in memory. When a triggering event included in the parameter stored in the memory occurs, the mobile terminal 20 collects wireless environment information according to the triggering event type, and sends an MR message including the collected wireless environment information to the base station 10. Transmit (step ②). According to an embodiment, the triggering event is an event of collecting the signal strength of the accessing base station 10, an event of collecting the signal strength of the neighboring base station 10, and the signal of the accessing base station 10 and the neighbor base station 10. It can be set to various types such as an event to collect all the intensities, and each event can be set to collect identification information (eg, cell ID) of base stations together.

Meanwhile, the mobile terminal 20 stores, in memory, codec change parameters to be referenced when codec is changed during a voice call, in addition to the parameters received through the RRC message. At this time, the codec change parameter may be generated and stored as a combination of various data stored in the mobile terminal 20, or may be received from a communication network as a value such as a SIP message or XML (eXtensible Marup Language), stored, and updated. there is. The mobile terminal 20 transmits an MR message to the base station 10 when a triggering event occurs based on the parameters received through the RRC message stored in the memory, and determines whether to change the codec according to the occurrence of the triggering event. do. When determining whether or not to change the codec, the mobile terminal 20 uses the codec change parameters stored in the memory (step ③).

2 is a block diagram illustrating functions of the mobile terminal of FIG. 1; The mobile terminal 20 may include a memory, a memory controller, one or more processors (CPUs), a peripheral interface, an input/output (I/O) subsystem, a display device, an input device, and communication circuitry. The memory may include high-speed random access memory, and may also include one or more magnetic disk storage devices, non-volatile memory such as flash memory devices, or other non-volatile semiconductor memory devices. Access to memory by the processor and other components, such as peripheral interfaces, may be controlled by the memory controller. The memory may store various types of information and program instructions, and the program is executed by a processor.

The peripheral interface connects the input/output peripheral devices of the mobile terminal 20 with the processor and memory. One or more processors execute various software programs and/or instruction sets stored in memory to perform various functions for the mobile terminal 20 and process data. The I/O subsystem provides an interface between peripheral interfaces and input/output peripherals such as display devices and input devices. The display device may use liquid crystal display (LCD) technology or light emitting polymer display (LPD) technology.

The processor is a processor configured to perform operations associated with the mobile terminal 20 and execute instructions, for example, to receive and manipulate input and output data between components of the mobile terminal 20 using instructions retrieved from memory. You can control it. The communication circuit performs communication through an external port or communication by an RF signal. The communication circuitry converts electrical signals to RF signals and vice versa, and communicates with the communication network, other mobile gateway devices, and communication devices via the RF signals.

Referring to FIG. 2 , the mobile terminal 20 may include a receiver 21, a parameter definer 23, an MR message transmitter 25, and a codec change determiner 27. These may be implemented in software and stored in a memory to be executed by a processor, or may be implemented in a module form as a combination of software and hardware and executed.

The receiver 21 receives the RRC message from the base station 10 and stores parameters included in the RRC message in memory. Here, the RRC message may be an rrcConnectionReconfiguration message. Parameters included in the RRC message may include an LTE frequency channel to be searched by the mobile terminal 20, a triggering event, and an RF value to be measured. The triggering event may include examples described in [Table 1] below, which are events defined in 3GPP TS 36.331.

<Table 1>

The parameter defining unit 23 defines codec change parameters to be referred to when changing a codec during a voice call, other than the parameters received through the RRC message, and stores them in a memory. Here, the codec change parameter represents a condition for changing a codec currently being used by the mobile terminal 20 to another codec according to a wireless environment.

The parameter definition unit 23 may define some of the codec change parameters as a combination of parameters received through the RRC message and stored in a memory. According to an embodiment, the parameter definer 23 may define a codec change event (Event_of_Change_Codec) among codec change parameters by combining trigger events received through the RRC message. For example, when the receiver 21 receives events A1, A3, and A4 described in [Table 1] as triggering events from the base station 10, the parameter definition unit 23 does not apply the events A1 and A4. , only event A3 can be defined as a codec change event (Event_of_Change_Codec) and stored in memory. That is, when triggering events A1 and A4 occur, the mobile terminal 20 transmits the MR message to the base station 10 and does not determine whether or not to change the codec. It transmits to the base station 10 and determines whether or not to change the codec.

The parameter definition unit 23 includes various data values stored in the memory of the mobile terminal 20, a Session Initiate Protocol (SIP) message transmitted by the communication system, or XML ( It can be defined based on eXtensible Markup Language), etc. For example, the parameter definition unit 23 is a minimum signal level (Threshold_EVS) capable of changing the EVS (Enhanced Voice Services) codec, a minimum signal level (Threshold_AMR_WB) capable of changing the AMR_WB (Adaptive Multi-Rate Wideband) codec, and an EVS codec. Minimum signal level that can be changed with AMR_WB codec (Threshold_Codec_EVS_to_AMR_WB), minimum signal level that can be changed from AMR_WB codec to AMR_NB (Adaptive Multi-Rate Narrowband) codec (Threshold_Codec_AMR_WB_to_AMR_NB), minimum number of MR message transmissions to determine codec change (Count_to_Trigger), codec Timer for determining change, duration for codec change (Duration_Time), wireless environment in which all voice outgoing calls must be processed as 3G CS (CSFB) (Forced_CSFB), RF value of serving cell measured by the terminal Codec change parameters, such as variables for correcting , may be defined and stored in memory.

The MR message transmission unit 25 continuously checks the wireless environment during a call, and when a triggering event stored in the memory occurs, RF information of the currently connected base station 10 (or cell) and RF of neighboring base stations (or cells) An MR message including information is transmitted to the base station 10. Here, the RF information may include base station (or cell) identification information (eg, cell ID), frequency channel information, signal strength, and the like. According to an embodiment, the MR message transmission unit 25 transmits the MR message to the base station 10 when a triggering event occurs, and informs the codec change determination unit 27 of the transmission of the MR message.

When the MR message transmission unit 25 transmits the MR message to the base station 10, the codec change determination unit 27 determines whether to change the codec currently being used during a voice call by reviewing codec change parameters. According to an embodiment, the codec change determination unit 27 sets a duration (Duration_Time) for codec change by driving a timer at the moment when the MR message transmission unit 25 first transmits the MR message to the base station 10. Then, it is determined whether the conditions of the codec change parameters are satisfied within the duration to determine whether to change the codec.

According to an embodiment, the codec change determination unit 27 determines whether the triggering event corresponds to a codec change event, and determines whether the number of transmissions of the MR message for the same event within the predetermined duration for the codec change is the minimum transmission of the MR message. The codec may be changed depending on whether or not the number of times (Count_to_Trigger) is greater than or not and whether conditions of other codec change parameters are satisfied. Here, the determination of whether or not the condition of the other codec change parameters is satisfied is, for example, comparison between the signal strength of the currently accessed base station (or cell) and the signal strength of the neighboring base station (or cell), the currently accessed base station (or cell) It may include comparison of the signal strength of and the minimum signal level at which the codec can be changed. However, the codec change determining unit 27 determines that the number of MR message transmissions for the same event within the codec change duration is less than the minimum number of MR message transmissions (Count_to_Trigger), even if all other codec change parameters satisfy the condition. can keep the existing currency, that is, the existing codec, without changing the codec. Therefore, the codec change determination unit 27 does not change the codec when the MR message is triggered by a temporary wireless environment change, but changes the codec only when the electric field environment in which the wireless environment continuously changes is bad. Even in this bad place, it improves the overall quality of voice call service by ensuring that voice calls are not disconnected and continue stably. If the number of transmissions of the MR message for the same event within the duration is greater than or equal to the minimum number of transmissions of the MR message, it means that the same radio environment change is repeated within the duration, which means that the electric field environment is bad. Therefore, it is necessary to change to a codec that occupies a low bandwidth in such a poor electric field environment. An example of the codec change may include changing to the AMR_WB codec during a voice call using the EVS codec and changing to the AMR_NB codec during a voice call using the AMR_WB codec. The codecs may include other voice codecs such as G.711.

During a voice call using the EVS codec, the codec change determination unit 27 determines that the triggering event corresponds to a codec change event, and that the number of transmissions of MR messages for the same event within the predetermined duration for codec change is the minimum transmission of the MR message. The number of times (Count_to_Trigger) or more, and the signal strength of the base station (or cell) currently being accessed is greater than the signal strength of the neighboring base station (or cell), and the signal strength of the base station (or cell) currently being accessed is different from the EVS codec to the AMR_WB codec If it is smaller than the minimum signal level that can be changed to (serving cell RF < Threshold_Codec_EVS_to_AMR_WB), a procedure for changing the currently used EVS codec to the AMR_WB codec may be performed, and if any of these is not satisfied, the existing codec may be maintained.

During a voice call using the AMR_WB codec, the codec change determining unit 27 determines that the triggering event corresponds to a codec change event and the transmission number of MR messages for the same event within the predetermined duration for codec change is the minimum transmission of the MR message. The number of times (Count_to_Trigger) or more, and the signal strength of the currently accessed base station (or cell) is greater than the signal strength of the neighboring base station (or cell), and the signal strength of the currently accessed base station (or cell) is different from AMR_WB codec to AMR_NB codec If it is smaller than the minimum signal level that can be changed to (serving cell RF< Threshold_Codec_AMR_WB_to_AMR_NB), a procedure for changing from the currently used AMR_WB codec to the AMR_NB codec may be performed, and if any of these is not satisfied, the existing codec may be maintained as it is.

Meanwhile, the codec change determining unit 27 determines the signal strength of the currently accessed base station (or cell) and the signal of a neighboring base station (or cell) when the MR message transmission unit 25 transmits the MR message to the base station 10. After comparing the strengths, if the signal strength of the neighboring base station (or cell) is greater than the signal strength of the currently connected base station (or cell), the handover command is waited for from the communication system without proceeding with the codec change procedure.

In the above description, the codec change determination unit 27 compares the triggering event and the codec change event, and compares the number of transmissions of the MR message for the same event within the duration and the minimum transmission number, as well as other codec change parameters It has been described that it is also determined whether the conditions are satisfied and the codec change is determined when all are satisfied, but this is not limited here. In another embodiment, the codec change determination unit 27 compares the triggering event and the codec change event, and when the triggering event corresponds to the codec change event, does not compare the number of transmissions of the MR message with the minimum number of transmissions, and the current The codec change may be determined by comparing the signal strength of the accessing base station (or cell) with the minimum signal level for the codec change. Alternatively, the codec change determination unit 27 does not compare the triggering event with the codec change event and the number of transmissions of the MR message with the minimum number of transmissions. Codec change may be determined by comparing only the minimum signal level for .

3 is a flowchart illustrating a method of changing a codec in a VoLTE terminal according to an embodiment.

Referring to FIG. 3 , the mobile terminal 20 receives an RRC message (rrcConnectionReconfiguration Message) from the base station 10 and stores parameters included in the RRC message in memory (S10). Parameters included in the RRC message may include an LTE frequency channel to be searched by the mobile terminal 20, a triggering event, and an RF value to be measured. The triggering event may include the examples shown in Table 1 above.

Next, the mobile terminal 20 may define and store codec change parameters to be referred to when changing a codec during a voice call, in addition to the parameters received from the base station 10 and stored in the memory, and store them in the memory (S20). Here, the codec change parameter indicates a condition for changing a codec currently being used by the mobile terminal 20 to another codec according to a wireless environment. The mobile terminal 20 may define some of the codec change parameters as a combination of parameters received through the RRC message and stored in a memory. According to an embodiment, the mobile terminal 20 may define a codec change event (Event_of_Change_Codec) among codec change parameters by combining a trigger event received through the RRC message. For example, when events A1, A3, and A4 described in [Table 1] are received from the base station 10 as triggering events, the mobile terminal 20 does not apply the events A1 and A4, and only the event A3 codec It can be defined as a change event (Event_of_Change_Codec) and stored in memory. In the mobile terminal 20, among the codec change parameters, the rest of the parameters except for some of the parameters are various data values stored in the memory of the mobile terminal 20, a Session Initiate Protocol (SIP) message transmitted by the communication system, or an eXtensible XML (XML) message. Markup Language), etc. For example, the mobile terminal 20 includes the minimum signal level at which the EVS codec can be changed (Threshold_EVS), the minimum signal level at which the AMR_WB codec can be changed (Threshold_AMR_WB), the minimum signal level at which the EVS codec can be changed to the AMR_WB codec (Threshold_Codec_EVS_to_AMR_WB), Codec change parameters such as the minimum signal level that can be changed from AMR_WB codec to AMR_NB codec (Threshold_Codec_AMR_WB_to_AMR_NB), the minimum number of MR message transmissions for codec change (Count_to_Trigger), and the duration for codec change (Duration_Time) can be defined and stored in memory. .

Next, the mobile terminal 20 continuously checks the wireless environment during the voice call and transmits an MR message to the base station 10 when the triggering condition is satisfied. It is possible to determine whether to change the current codec to another codec (S30). The mobile terminal 20 determines whether the triggering event corresponds to a codec change event and whether the number of transmissions of MR messages for the same event within the preset duration for codec change corresponds to or more than the minimum number of transmissions of MR messages (Count_to_Trigger). , And the codec can be changed according to whether the conditions of other codec change parameters are satisfied. Here, the determination of whether the condition of the other codec change parameters is satisfied is, for example, comparison between the signal strength of the currently accessed base station (or cell) and the signal strength of the neighboring base station (or cell), the current access base station (or cell) It may include comparison of signal strength and minimum signal level at which codec change is possible. An example of the codec change may include changing to the AMR_WB codec during a voice call using the EVS codec and changing to the AMR_NB codec during a voice call using the AMR_WB codec. The mobile terminal 20 compares the signal strength of the currently accessed base station (or cell) with the signal strength of the neighboring base station (or cell), and compares the signal strength of the currently accessed base station (or cell) with the signal strength of the neighboring base station (or cell). If the signal strength is greater, the codec change procedure is not performed and a handover command is received from the communication system. Alternatively, the mobile terminal 20 compares the triggering event and the codec change event, and when the triggering event corresponds to the codec change event, does not compare the number of transmissions of the MR message with the minimum number of transmissions, and the currently accessed base station (or Codec change may be determined by comparing the signal strength of the cell) with the minimum signal level for codec change. Alternatively, the mobile terminal 20 does not compare the triggering event with the codec change event and the number of transmissions of the MR message with the minimum number of transmissions. Codec change may be determined by comparing only signal levels.

FIG. 4 is a flowchart illustrating an embodiment of the codec change determination step of FIG. 3, in which the mobile terminal 20 changes the EVS codec to the AMR_WB codec in consideration of wireless environment conditions during a voice call.

Referring to FIG. 4 , the mobile terminal 20 continuously checks the wireless environment during a voice call using the EVS codec to determine whether the MR transmission triggering condition is satisfied (S401). The mobile terminal 20 may determine that the triggering condition is satisfied when the triggering event received through the RRC message from the base station 10 and stored in the memory is the same as the event occurring in the current wireless environment. If the wireless environment does not satisfy the triggering condition (S401, No), the mobile terminal 20 maintains the existing call, that is, the existing EVS codec (S410).

Next, when the wireless environment satisfies the triggering condition (S401, Yes), the mobile terminal 20 includes the RF information of the currently accessed base station (or cell) 10 and the RF information of the neighboring base station (cell). The MR message may be transmitted to the base station 10 (S402). Here, the RF information includes base station (or cell) identification information (eg, cell ID), signal strength, and the like. At this time, the mobile terminal 20 may set a duration (Duration_Time) for codec change by driving a timer at the moment when the MR message is first transmitted to the base station 10 .

After transmitting the MR message, the mobile terminal 20 determines whether the signal strength of the currently accessed base station 10 (or cell) is greater than or equal to the signal strength of the neighboring base station 10 (or cell) (S403). If the signal strength of the currently accessed base station 10 is smaller than the signal strength of the neighboring base station 10 (S403, No), the mobile terminal 20 maintains the existing codec without performing an operation of determining whether to change the codec, It waits to receive a handover command from the base station 10 (S404). According to another embodiment, the comparison of signal strengths may include comparison of signal strengths of the currently connected base station 10 and signal strengths of neighboring base stations 10 as well as comparison of various conditions according to a defined triggering event type.

Meanwhile, when the signal strength of the currently accessed base station (or cell) is equal to or greater than the signal strength of the neighboring base station (or cell) (S403, Yes), the mobile terminal 20 determines that the signal strength of the currently accessed base station (or cell) is EVS. It is determined whether the codec is lower than the minimum signal level (Threshold_EVS) that can be changed (S405). If the signal strength of the currently accessed base station (or cell) is equal to or higher than the minimum signal level at which the EVS codec can be changed (S405, No), the mobile terminal 20 maintains the existing call, that is, the existing EVS codec (S410).

Next, if the signal strength of the currently accessed base station (or cell) is less than the minimum signal level at which the EVS codec can be changed (S405, Yes), the mobile terminal 20 determines that the currently occurring trigger event is a codec change event (Event_of_Change_Codec). It is further determined whether it is included in (S406). If the currently occurring trigger event is not included in the codec change event (S406, No), the mobile terminal 20 maintains the existing call, that is, the existing EVS codec (S410).

Next, if the currently occurring trigger event is included in the codec change event (S406, Yes), the mobile terminal 20 further determines whether the number of MR message transmissions according to the same event is equal to or greater than the minimum number of MR message transmissions (Count_to_Trigger). (S407). If the number of MR message transmissions according to the same event is less than the minimum number of MR message transmissions (S407, No), the mobile terminal 20 maintains the existing call, that is, the existing EVS codec (S410).

Next, if the number of MR message transmissions according to the same event is equal to or greater than the minimum number of MR message transmissions (S407, Yes), the mobile terminal 20 changes the signal strength of the currently accessed base station (or cell) from the EVS codec to the AMR_WB codec. It is further determined whether it is smaller than the changeable minimum signal level (Threshold_Codec_EVS_to_AMR_WB) (S408). If the signal strength of the currently accessed base station (or cell) is equal to or higher than the minimum signal level that can be changed from the EVS codec to the AMR_WB codec (S408, No), the mobile terminal 20 maintains the existing call, that is, the existing EVS codec (S410) . On the other hand, if the signal strength of the currently accessed base station (or cell) is less than the minimum signal level that can be changed from the EVS codec to the AMR_WB codec (S408, YES), the mobile terminal 20 performs a procedure for changing the EVS codec to the AMR_WB codec. Start (S409). In step 402 of the above embodiment, the mobile terminal 20 sets a duration (Duration_Time) for determining a codec change by driving a timer at the moment when the MR message is transmitted to the base station 10 for the first time. Satisfaction of the conditions from step S403 to step S407 in the above embodiment must be made within the above duration. If any one of the conditions of steps S403 to S407 is not satisfied within the duration, the mobile terminal 20 may not initiate the codec change in step S409.

FIG. 5 is a flowchart illustrating another embodiment of the codec change determination step of FIG. 3, in which the mobile terminal 20 changes to the AMR_NB codec in consideration of the radio environment situation during a voice call using the AMR_WB codec.

Referring to FIG. 5 , the mobile terminal 20 continuously checks the wireless environment during the voice call using the AMR_WB codec to determine whether the MR transmission triggering condition is satisfied (S501). The mobile terminal 20 may determine that the triggering condition is satisfied when the triggering event received through the RRC message from the base station 10 and stored in the memory is the same as the event occurring in the current wireless environment. If the wireless environment does not satisfy the triggering condition (S501, No), the mobile terminal 20 maintains the existing call, that is, the AMR_WB codec (S510).

Next, when the wireless environment satisfies the triggering condition (S501, Yes), the mobile terminal 20 includes the RF information of the currently accessed base station (or cell) 10 and the RF information of the neighboring base station (cell). The MR message may be transmitted to the base station 10 (S502). Here, the RF information includes base station (or cell) identification information (eg, cell ID), signal strength, and the like. At this time, the mobile terminal 20 may set a duration (Duration_Time) for codec change by driving a timer at the moment when the MR message is first transmitted to the base station 10 .

After transmitting the MR message, the mobile terminal 20 determines whether the signal strength of the currently accessed base station (or cell) is greater than or equal to the signal strength of the neighboring base station (or cell) (S503). When the signal strength of the currently accessed base station (or cell) is smaller than the signal strength of the neighboring base station (or cell) (S503, No), the mobile terminal 20 does not perform an operation of determining whether to change the codec any longer and While maintaining the codec, it waits to receive a handover command from the base station 10 (S504). According to another embodiment, the comparison of signal strengths may include comparison of signal strengths of the currently connected base station 10 and signal strengths of neighboring base stations 10 as well as comparison of various conditions according to a defined triggering event type.

Meanwhile, when the signal strength of the currently accessed base station (or cell) is equal to or greater than the signal strength of the neighboring base station (or cell) (S503, Yes), the mobile terminal 20 determines that the signal strength of the currently accessed base station (or cell) is AMR_WB It is determined whether or not the codec change is lower than the minimum signal level (Threshold_AMR_WB) (S505). If the signal strength of the currently accessed base station (or cell) is equal to or higher than the minimum signal level at which the AMR_WB codec can be changed (S505, No), the mobile terminal 20 maintains the existing call, that is, the existing AMR_WB codec (S510).

Next, when the signal strength of the currently accessed base station (or cell) is less than the minimum signal level at which the AMR_WB codec can be changed (S505, Yes), the mobile terminal 20 determines that the currently occurring trigger event is a codec change event (Event_of_Change_Codec). It is further determined whether it is included in (S506). If the currently occurring trigger event is not included in the codec change event (S506, No), the mobile terminal 20 maintains the existing call, that is, the existing AMR_WB codec (S510).

Next, if the currently occurring trigger event is included in the codec change event (S506, Yes), the mobile terminal 20 further determines whether the number of MR message transmissions according to the same event is equal to or greater than the minimum number of MR message transmissions (Count_to_Trigger). (S507). If the number of MR message transmissions according to the same event is less than the minimum number of MR message transmissions (S507, No), the mobile terminal 20 maintains the existing call, that is, the existing AMR_WB codec (S510).

Next, if the number of MR message transmissions according to the same event is greater than or equal to the minimum number of MR message transmissions (S507, Yes), the mobile terminal 20 changes the signal strength of the base station (or cell) being currently accessed from the AMR_WB codec to the AMR_NB codec. It is further determined whether the signal level is lower than the changeable minimum signal level (Threshold_Codec_AMR_WB_to_AMR_NB) (S508). If the signal strength of the currently accessed base station (or cell) is not smaller than the minimum signal level that can change from the AMR_WB codec to the AMR_NB codec (S508, No), the mobile terminal 20 maintains the existing call, that is, the AMR_WB codec (S510). ). On the other hand, if the signal strength of the currently accessed base station (or cell) is less than the minimum signal level that can be changed from the AMR_WB codec to the AMR_NB codec (S508, YES), the mobile terminal 20 performs a procedure for changing the AMR_WB codec to the AMR_NB codec. Start (S509).

In step 502 of the above embodiment, the mobile terminal 20 may set a duration (Duration_Time) for codec change by driving a timer at the moment of first transmitting the MR message to the base station 10 . Satisfaction of the conditions from step S503 to step S507 in the above embodiment must be made within the above duration. If any one of the conditions of steps S503 to S507 is not satisfied within the above duration, the mobile terminal 20 may not initiate the codec change in step S509.

While this specification contains many features, such features should not be construed as limiting the scope of the invention or the claims. Also, features described in separate embodiments in this specification may be implemented in combination in a single embodiment. Conversely, various features that are described in this specification in a single embodiment may be implemented in various embodiments individually or in combination as appropriate.

Although actions are described in a particular order in the drawings, it should not be understood that such actions are performed in the specific order as shown, or that the actions are performed in a series of sequential order, or that all described actions are performed to achieve a desired result. . Multitasking and parallel processing can be advantageous in certain circumstances. In addition, it should be understood that the division of various system components in the above-described embodiments does not require such division in all embodiments. The program components and systems described above may generally be implemented as a package in a single software product or multiple software products.

The method of the present invention as described above may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily performed by a person skilled in the art to which the present invention belongs, it will not be described in detail.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention to those skilled in the art to which the present invention belongs, and thus the above-described embodiments and It is not limited by drawings.

10: base station
20: mobile terminal
21: receiver
23: parameter definition unit
25: MR message transmission unit
27: codec change judgment unit

Claims (16)

An apparatus for changing a codec according to a wireless environment in a terminal providing a voice call,
a receiving unit receiving a Radio Resource Control (RRC) message from a communication network and storing parameters including a triggering event included in the RRC message in a memory;
a parameter definition unit for defining codec change parameters with reference to the parameters stored in the memory and storing them in the memory;
When the triggering event occurs during the voice call, an MR message transmission unit for transmitting a Measurement Report (MR) message including collected wireless environment information to the communication network; and
A codec change determination unit for determining whether to change the codec by referring to the transmission of the MR message and the codec change parameter;
The parameter definition unit,
A codec change event is defined as the codec change parameter, at least one of the triggering events is defined as the codec change event,
The codec change determination unit,
Apparatus for determining whether the codec is changed when the generated triggering event corresponds to the codec change event. delete According to claim 1,
The parameter definition unit,
Further defining the minimum number of transmissions of MR messages as the codec change parameter;
The codec change determination unit,
and determining whether the codec is changed by further comparing the number of transmissions of the MR message for the same codec change event with the minimum number of transmissions of the MR message. According to claim 1,
The parameter definition unit,
Define a minimum signal level at which codec change is possible as the codec change parameter,
The codec change determination unit,
The apparatus characterized in that it determines whether to change the codec by comparing the signal strength of the currently accessed cell with the minimum signal level. According to claim 4,
The codec change determination unit,
and changing the current codec to another codec when the signal strength of the currently accessed cell is less than the minimum signal level. According to claim 5,
The current codec is an Enhanced Voice Services (EVS) codec and the other codec is an Adaptive Multi-Rate Wideband (AMR-WB) codec, or
The current codec is an AMR-WB codec and the other codec is an adaptive multi-rate narrowband (AMR-NB) codec. The method of any one of claims 1 and 3 to 6,
The parameter definition unit,
Define a duration for codec change as the codec change parameter,
The codec change determination unit,
and driving a timer based on transmission of the MR message and determining whether to change a codec within the duration. According to claim 1,
The codec change determination unit,
An apparatus that waits for a handover command without determining whether to change a codec when the signal strength of a currently accessed cell is equal to or greater than the signal strength of a neighboring cell. A method for changing a codec according to a wireless environment in a terminal providing a voice call,
Receiving a Radio Resource Control (RRC) message from a communication network and storing a parameter including a triggering event included in the RRC message in a memory;
defining codec change parameters with reference to the parameters stored in the memory and storing them in the memory;
transmitting a MeasurementReport (MR) message including collected wireless environment information to the communication network when the triggering event occurs during the voice call; and
Determining whether to change the codec by referring to the transmission of the MR message and the codec change parameter;
The step of defining and storing the codec change parameters in the memory,
A codec change event is defined as the codec change parameter, at least one of the triggering events is defined as the codec change event,
The step of judging is
When the generated triggering event corresponds to the codec change event, determining whether to change the codec. delete According to claim 9,
The step of defining and storing the codec change parameters in the memory,
Further defining the minimum number of transmissions of MR messages as the codec change parameter;
The determining step is
and determining whether the codec is changed by further comparing the number of transmissions of the MR message for the same codec change event with the minimum number of transmissions of the MR message. According to claim 9,
The step of defining and storing the codec change parameters in the memory,
Define a minimum signal level at which codec change is possible as the codec change parameter,
The determining step is
A method characterized in that determining whether to change a codec by comparing the signal strength of a currently accessed cell with the minimum signal level. According to claim 12,
The determining step is
and changing the current codec to another codec when the signal strength of the currently accessed cell is less than the minimum signal level. According to claim 13,
The current codec is an Enhanced Voice Services (EVS) codec and the other codec is an Adaptive Multi-Rate Wideband (AMR-WB) codec, or
Wherein the current codec is an AMR-WB codec and the other codec is an Adaptive Multi-Rate Narrowband (AMR-NB) codec. The method of any one of claims 9 and 11 to 14,
The step of defining and storing the codec change parameters in the memory,
Define a duration for codec change as the codec change parameter,
The determining step is
and driving a timer based on transmission of the MR message and determining whether to change a codec within the duration. According to claim 9,
The determining step is
A method characterized by waiting for a handover command without determining whether to change a codec when the signal strength of a currently accessed cell is equal to or greater than the signal strength of a neighboring cell.

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