KR20060089593A - Method for disperse user equipments to non preferred frequencies in multimedia broadcast multicast service system - Google Patents

Abstract

According to the present invention, when a session of an MBMS service having a preferred frequency band is terminated in a mobile communication system using a code division multiple access system, a terminal having no dedicated channel gathered in a cell of the preferred frequency band is effectively different from each other. It is about how to disperse. When the session of the MBMS service having the preferred frequency band ends, the message indicating the end of the session of the MBMS service includes time information until the start of the next session of the service, thereby providing a terminal of the state according to the time information. Do not scatter or disperse into other frequency bands.

MBMS, FLC, LDI, Duration time between sessions, Session stop

Description

METHODOLOGY FOR DISPERSE USER EQUIPMENTS TO NON PREFERRED FREQUENCIES IN MULTIMEDIA BROADCAST MULTICAST SERVICE SYSTEM}

1 is a diagram illustrating an example of a cell layer structure and an MBMS FLC overlapping a conventional service area.

2 shows an example of the use of a typical MBMS LDI.

3 is a diagram illustrating a problem of using a general MBMS LDI.

4 illustrates an MBMS LDI method according to a preferred embodiment of the present invention.

5 illustrates the operation of a CRNC in accordance with a preferred embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multimedia broadcast / multicast service (hereinafter referred to as "MBMS") system, and more particularly, to a method for dispersing terminals in unpreferred frequency bands using time information informing a session start. will be.

Today, due to the development of communication technology, the services provided by the mobile communication system using the Wideband Code Division Multiple Access (CDMA) method are not only a conventional voice service but also a large amount of data. It is developing into a packet service communication that transmits and a multimedia broadcast / communication capable of transmitting a multimedia service. Accordingly, in order to support the multimedia broadcasting / communication, an MBMS service that provides a service from one or more multimedia data sources to a plurality of user equipments (hereinafter referred to as UEs) has been discussed.

The MBMS service refers to a service for transmitting the same multimedia data to multiple receivers through a wireless network. In this case, by allowing multiple receivers to share one radio channel, it is possible to save radio transmission resources. The MBMS service supports multimedia transmission forms such as real-time video, audio, still images, and text. The MBMS service is a service that can simultaneously provide audio data and video data according to the multimedia transmission format, and requires a large amount of transmission resources. In the case of the MBMS service, since the same data must be transmitted to a plurality of cells in which users are located, one-to-one (Point to Point: 'PtP') or one-to-many depending on the number of users located in each cell. : Hereinafter called 'PtM') Connection is made.

In a recent MBMS system, a frequency layer convergence is allocated for a more desirable frequency for each of the MBMS services that can be provided, and for allowing UEs using the MBMS services to receive a desired MBMS service at the preferred frequency as much as possible. Convergence, hereinafter referred to as "FLC" technology. The FLC information indicates the corresponding preferred frequencies for the MBMS services. In other words, the FLC of MBMS is a method of moving a terminal to a preferred frequency band for each service in order to provide a service only in one frequency for each possible service without providing one service in all frequencies overlapping the same region.

1 is a diagram illustrating an example of a cell layer structure and an MBMS FLC overlapping a conventional service area. 1 illustrates a cell structure in which the same service area is overlapped with another frequency, that is, frequency 1, frequency 2, frequency 3, and frequency 4. Reference numeral 101 denotes a frequency 1, 111 denotes a frequency 2, 121 denotes a frequency 3, 131 denotes a frequency 4, and 141 denotes a controlling radio network controller (hereinafter referred to as "CRNC") for controlling a cell of the frequency band. Indicates. FLC does not provide one service in all cells of frequency 1, frequency 2, frequency 3, and frequency 4 that overlap each other in the same region as shown in FIG. The method of shifting to the preferred frequency band.

Referring to FIG. 1 by way of example, in step 1, the CRNC of step 141 indicates that a session of a specific MBMS is to be started from a serving packet wireless service support node (hereinafter referred to as "SGSN") through an Iu interface. Receive the start message. Upon receiving the session start message in step 2, the CRNC of 141 selects a preferred frequency band for the MBMS service. In FIG. 1, it is assumed that frequency 2 of 111 is selected as a preferred frequency for a session of the service. In step 3, information of the preferred frequency 2 for the MBMS service selected in step 2 is transmitted to all frequencies, that is, frequencies 1 of 101, frequencies 2 of 111, frequencies 3 of 121, and frequencies 4 of 131.

In step 4, among the terminals to receive the session of the MBMS service that has received the preferred frequency information, the terminals at the non-preferred frequencies (101, 121, 131) move to the preferred frequency (111) and are located at the preferred frequency (111). Terminals continue to stay at the preferred frequency 111, and process 4 is called FLC as described above. Terminals attempting to receive the session of the service by the FLC are concentrated at the preferred frequency 111 during the session.

2 is a diagram illustrating an example of using a general MBMS LDI. The Layer Dispersion Indicator (hereinafter referred to as "LDI") is a method of dispersing terminals concentrated in the preferred frequency of the MBMS service by the FLC described with reference to FIG. 1 into all frequency bands when the session ends.

In FIG. 2, 201, 211, 221, and 231 indicate frequency 1, frequency 2, frequency 3, and frequency 4 overlapping the same service area, and 241 indicates a CRNC for controlling a cell of the frequency band. In step 1, the CRNC of 241 receives a session stop message indicating that a specific MBMS session is completed from the SGSN through the lu interface. In FIG. 2, it is assumed that frequency 2 of 211 is used as a preferred frequency of the specific MBMS session.

In step 2, the CRNC that receives the session stop message signals an LDI. The LDI is transmitted through an MBMS Control Channel (hereinafter, referred to as “MCCH.”) In step 3, terminals gathered at the preferred frequency 211 receiving the LDI are no longer connected to the MBMS service. Recognizing that there is no need to gather at the preferred frequency 211 for a session, it is distributed and moved to other frequencies 201, 221, 231. The method of distribution is the most selectable cell with the best radio strength already defined. You can also move or use a separate distribution mechanism.

3 is a diagram illustrating a problem that may appear when the FLC and the LDI of FIGS. 1 and 2 are applied. 301, 311, 321, and 331 of FIG. 3 indicate frequency 1, frequency 2, frequency 3, and frequency 4 overlapping the same service area, and 341 indicates a CRNC for controlling a cell of the frequency band. 3 shows a continual procedure from the session stop of a particular MBMS session with a preferred frequency to the next session start of the service. However, it is assumed that the next session start starts within a short time from the previous session stop.

In step 1, the CRNC receives a session stop from SGSN indicating that the session of a specific MBMS service having the preferred frequency 311 is finished. In step 2, the LDI is signaled. In step 3, terminals gathered at the preferred frequency 311 for the session of the service receive the LDI and distribute the LDI to other frequencies 301, 321, and 331.

However, the CRNC will receive the next session start of the service in a short time in step 4. Then, in step 5, the preferred frequency 311 is selected for the next session of the service, and the terminals, which are scattered to other frequencies 301, 321, and 331 by steps 2 and 3, are again processed in steps 6 and 6. By 7 to the preferred frequency 311. That is, if the time between the previous session stop of the process 1 and the next session start of the process 4 is not sufficient, scattering the terminals to other frequencies by the processes 2 and 3 is useless, and the useless procedure The measurement of the terminal (Measurement), cell reselection, uplink / downlink signaling, etc. are caused. This is because if the next session is started soon, even if the terminals are scattered, they must be re-focused again to the preferred frequency.

As described above, in the case of FIG. 3 according to the related art, when signaling the LDI without considering the time from the session stop of the specific MBMS service having the preferred frequency to the next session start process of the service, the LDI is immediately signaled. If the next session begins, useless terminals are measured, cell reselected, and up-dated by the procedure of distributing the terminals gathered in the preferred frequency band to different frequency bands and concentrating the terminals scattered again by the start of the next session. There was a problem that the link / downlink signaling is caused.

Accordingly, an object of the present invention, which was devised to solve the problems of the prior art operating as described above, is that, when a session of a particular MBMS having a preferred frequency is over, the terminals gathered at the preferred frequency for the session are uselessly different. It is to provide an efficient MBMS LDI method that does not scatter to the frequency band.

Another object of the present invention is time information until the next session start of the service of the session stop to disperse the terminals having no dedicated channel receiving the MBMS service having the preferred frequency band efficiently into another frequency band when the session is over. It is to provide a method using.

It is yet another object of the present invention to define a time information parameter to the next session start that can be transmitted via a session stop message and to provide a method of operating the CRNC according to the parameter.

In order to achieve the above object, an embodiment of the present invention provides a multimedia broadcast / multicast service (MBMS) service in a method for distributing terminals to non-preferred frequency bands in a multimedia broadcast / multicast service system. Receiving the information about the time taken until the next session start of the MBMS service at the end of the session, and based on the time taken until the next session start of the MBMS service has a preferred frequency, hierarchical dispersion indicator Determining whether to set (LDI), and transmitting a session stop message to terminals receiving the MBMS service.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily flow the gist of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

The present invention proposes an MBMS LDI method in which, when a session of a specific MBMS having a preferred frequency ends and immediately starts a next session, terminals gathered at the preferred frequency for the session are not unnecessarily scattered to other frequency bands.

4 is a diagram illustrating a MBMS LDI signaling method according to a preferred embodiment of the present invention to solve the problem shown in FIG.

Reference numeral 401 denotes terminals which received a specific MBMS session having a preferred frequency in the cell of the preferred frequency, and 402 denotes a CRNC for controlling the cell of the preferred frequency where the terminals of the 401 are located. 403 denotes an SGSN connected to the CRNC, and 404 denotes a Broadcast Multicast Service Center (hereinafter, referred to as a 'BM-SC') that provides the MBMS service. Since the session of the MBMS service having the preferred frequency is terminated in step 411, as the session of the MBMS service ends in step 421, the BM-SC 404 transmits a session stop message to the SGSN 403.

The session stop message includes a service ID and a session ID. The service ID represents the service, and the session ID is an identifier representing a session of the service. When transmitting a session stop message from the BM-SC 404 to a lower core network (CN), the BM-SC 404 informs the time information until the next session start of the service. The time information is included in the session stop message of steps 421 and 422 and transmitted to the CRNC 402.

In step 431, the CRNC 402 receiving the session stop message determines whether to perform LDI transmission based on the received time information. If the next session start begins within a short time, the CRNC 402 does not signal the LDI to prevent the terminals 401 from being scattered to other frequencies. Here, signaling no LDI indicates process 441.b, in which only a session stop message including no LDI is transmitted. When the terminal 401 receives the session stop message in step 441.b, the terminals 401 follow the cell movement procedure defined in the existing REL-99 without performing a scattering operation on another frequency.

If the next session start starts after a sufficiently long time in step 431, the CRNC 402 transmits the LDI in the session stop message in order to scatter the terminals 401 to different frequencies in step 441.a. When the terminals 401 receive the session stop message including the LDI, the terminals 401 scatter the other frequencies. The scattering operation to different frequencies may follow a separately defined mechanism or reselect a selectable cell with the best radio strength.

5 is a diagram illustrating an operation of a CRNC according to the embodiment of FIG. 4.

In step 501, a session stop message is received from the SGSN through the lu interface. In step 502, the CRNC determines whether the session of the session stop message is a session of MBMS service having a preferred frequency, and checks whether the time information until the next session start included in the session stop message is long enough. For example, if the time taken to start the next session is equal to or greater than a predetermined threshold, the process is a session of the MBMS service having the preferred frequency in step 502, and if the time taken to start the next session is long enough, go to step 511. The LDI is transmitted along with the session stop message information to the UEs in the preferred frequency through the MCCH.

However, if both conditions in step 502 are not true, go to step 512 and transmit through the session stop message MCCH, where the LDI is not included. In addition, in step 502, the process proceeds to step 512 even if only one of the two conditions is not true.

The LDI signaling method may have various methods. In FIG. 5, when the terminals are scattered to different frequencies, LDI is set to true and transmitted, and if the terminals are not scattered to other frequencies, In order to follow the terminal measurement and cell reselection method defined in REL-99, the method that does not transmit LDI is shown.

In addition, when the terminals are to be scattered to other frequencies, the LDI may be set to true, and when the terminals are not to be scattered to other frequencies, the LDI may be set to false.

Table 1 below shows an example of time information required until the next session start that can be transmitted through the session stop message of steps 421 and 422 of FIG. 4 and step 501 of FIG. 5.

In Table 1, the time taken to start the next session is expressed in seconds and days. However, the time information of Table 1 is only one embodiment, and the range of information to be transmitted may be different.

Table 2 below shows another example of time information required until the next session start that can be transmitted through the session stop message of steps 421 and 422 of FIG. 4 and step 501 of FIG. 5. In the following Table 2, if the time taken until the next session start is not included in the session stop message, this means that the time taken until the next session start exceeds 1024 seconds. Otherwise, the time required to start the next session is signaled in seconds as shown in Table 2 below. However, the time information shown in Table 2 below is only one embodiment, and the range of information to be transmitted may be different.

Table 3 below shows another example of time information required until the next session start that can be transmitted through the session stop message of steps 421 and 422 of FIG. 4 and step 501 of FIG. 5. In Table 3 below, the interval between two integers is not recognized as 1 second, but as 2 seconds, and twice the time is represented with the same amount of signaling as in Table 2 above. For example, 0 represents 2 seconds, 1 represents 4 seconds, 2 represents 6 seconds, and 1024 represents 2048 seconds. Table 3 below shows an example of displaying a long time interval while reducing signaling overhead with a predetermined interval, and two seconds representing an interval between two integers is only one example and may have a different value. You can also have time units in minutes or hours rather than seconds.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

In the present invention operating as described in detail above, the effects obtained by the representative ones of the disclosed inventions will be briefly described as follows.

The present invention, by receiving the time information until the next session start in the CRNC to determine whether or not the terminals stayed in the preferred frequency, so as not to cause unnecessary terminal measurement, cell reselection, uplink / downlink signaling, etc. This reduces the power consumption and increases the efficiency of the mobile communication system.

Claims (8)

A method for distributing terminals in a non-preferred frequency band in a multimedia broadcast / multicast service system, Receiving information on the time taken until the next session start of the MBMS service at the end of a session of a multimedia broadcast / multicast service (MBMS) service; If the MBMS service has a preferred frequency and the time taken until the next session start is sufficiently long, setting a layer distribution indicator (LDI) in a session stop message and transmitting the same to the terminals receiving the MBMS service; If the MBMS service does not have a preferred frequency and the time taken to start the next session is not long enough, sending a session stop message not configured for the LDI to terminals receiving the MBMS service. Characterized in that the method. The method of claim 1, wherein the session stop message is And a service ID indicating the MBMS service and a session ID indicating the session. 2. The method of claim 1, wherein if the MBMS service has a preferred frequency and the time taken until the next session start is long enough, the layer stop indicator (LDI) is set to true in the session stop message and transmitted. Said method. 2. The method of claim 1, wherein if the MBMS service does not have a preferred frequency or the time taken until the next session start is not long enough, And setting the LDI to false in the session stop information. The method of claim 1, wherein the information about the time taken until the start of the next session comprises: Said method as Second and Day. The method of claim 1, wherein the information about the time taken until the start of the next session comprises: Said method characterized in that it is represented by a predetermined time unit within a predetermined time range. 6. The method of claim 5, wherein if the session stop message does not include information about the time taken until the next session start, Said time period until said next session start exceeds said predetermined time range. The method of claim 6, wherein the predetermined time unit, The method of any one of seconds, minutes and hours.

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