KR20110013818A - Method for controlling handover parameter adaptively in multicast and broadband service environment - Google Patents

Abstract

PURPOSE: A method for adaptively controlling a handover parameter in an MBS(Multicast and Broadcast Service) environment is provided to control the handover parameter based on the sorts of the mobile terminal. CONSTITUTION: According to a movement of a mobile terminal, a handover type is determined(600). If the handover is within an MBS domain(602), the handover parameter maintains by the set standard value(606). In the handover is to a non-MBS region from an MBS region, the hand over parameter is changed into a larger value than the standard value(604). If the hand over is from a non-MBS region to a non-MBS region, the hand over parameter is changed into a smaller value than the standard value(608).

Description

Adaptive handover parameter control method in multicast broadcasting service environment {METHOD FOR CONTROLLING HANDOVER PARAMETER ADAPTIVELY IN MULTICAST AND BROADBAND SERVICE ENVIRONMENT}

The present invention relates to a method for adaptive handover parameter adjustment in a multicast broadcast service environment. More particularly, the present invention relates to a handover type (MBS) of a mobile terminal in a multicast and broadcast service (MBS) environment. Handover parameters (eg, hysteresis) according to handover, handover between the MBS region and the non-MBS region, thereby reducing overall handover delay and increasing wireless bandwidth efficiency. The present invention relates to an adaptive handover parameter setting method in a cast broadcast service environment.

Currently, portable Internet services are generally used in a one-to-one transmission, that is, a sender transmits data to one receiver.

This unicast scheme causes congestion in the network when the sender and receiver are one-to-many. In addition, the next-generation mobile Internet service is based on the transmission of multimedia data, there is a problem that it is impossible to transmit each data to all of the numerous recipients.

In order to solve this problem, a 'multicast transmission method' has emerged in a manner that can reduce network congestion and effectively use bandwidth. Multicast transmission is a one-to-many or many-to-many transmission method. Unlike unicast, a single data packet is transmitted to multiple receivers at the same time. It is a technique to improve network resources and system overload by transmitting it.

In addition to the spread of mobile terminals, such multicast transmission technology has become one of the technologies that must be applied even in a mobile Internet environment. In particular, since the multicast technology of the wired network causes a problem due to the mobility of the terminal in the portable Internet environment, researches for supporting the mobility of the terminal along with the existing multicast issues have been actively conducted. The "multicast broadcast service area (MBS area)" is proposed in IEEE 802.16e for effective IP multicast.

In other words, it is advantageous to provide a service in a multicast method rather than the existing unicast method. For this purpose, the concept of "MBS area" has been standardized in IEEE802.16e, and MBS service for Mobile IPTV, which has recently emerged, is prepared. have.

In addition, considering the handover delay value and the efficiency of radio resources, unlike conventional terminals, MBS service users have different tendencies, so in a situation where MBS areas and Non MBS areas are mixed in a network, It is important to meet both the requirements (handover delay and radio resource efficiency). Therefore, it is necessary to apply hysteresis, which is one of the basic properties of handover, differently according to the mobile situation of the terminal.

In the existing mobile Internet service field, there is a method of improving handover performance by adjusting the handover parameter (Hysteresis), which prevents the load on a specific cell and equalizes the cell load in the entire network.

However, these conventional methods use the same method (i.e., one-to-one) between cells, and this method (policy) distributes MBS users in the MBS service environment, which causes a problem in that the MBS area is unnecessarily enlarged.

Accordingly, the present invention allows an MBS user to receive a service within the MBS area if possible in a multicast broadcasting service (MBS) environment (that is, "quick entry into the MBS area", "deviation of the MBS area" The purpose of the present invention is to provide an adaptive handover parameter setting method in a multicast broadcast service environment.

That is, the present invention provides a handover parameter (eg, hysteresis) according to the handover type of the mobile terminal (handover in the MBS region, handover between the MBS region and the Non MBS region) in a multicast broadcasting service (MBS) environment. It is an object of the present invention to provide an adaptive handover parameter setting method in a multicast broadcast service environment that can dynamically adjust).

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to achieve the above object, the present invention provides a method for adjusting a handover parameter in a multicast broadcast service (MBS) environment, the method comprising: determining a handover type according to a movement of a mobile terminal; Adjusting a handover parameter according to one of a handover, a handover from the MBS area to the non-MBS area, and a handover from the non-MBS area to the MBS area; It includes.

The present invention as described above, by actively controlling the handover in the multicast broadcast service (MBS) environment, that is, by dynamically controlling the handover parameter (hysteresis) according to the handover type of the mobile terminal, thereby reducing the overall handover delay There is an effect that can reduce and efficiently use the overall cell radio resources (wireless bandwidth).

In addition, the present invention allows the MBS user to perform a "fast" handover when entering the MBS area from the Non MBS area, and vice versa, because the "slow" handover is performed "low". It is effective to reduce the incidence of ping pong for the terminal.

The foregoing and other objects, features 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, in which: There will be. In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is an explanatory diagram for packet transmission in an MBS area.

The development of the mobile internet has increased the weight of multimedia broadcasting services of users. Especially, in the situation where multiple users receive the same data, such as multimedia broadcasting services, the conventional one-to-one service is disadvantageous in many ways. Do. Therefore, there is a need for a new method of efficiently providing a multimedia broadcasting service, in which IEEE802.16e refers to the concept of "Multicast and Broadcast Service (MBS) Zone" (hereinafter referred to as "MBS Zone"). Suggested. The concept is to bundle multiple base stations into one group to provide the same data.

In the MBS region 100, the multicast service provides the same Connection Identifier (CID), as shown in FIG. 1, to reduce latency by reusing MBS-related parameters and multicast CIDs used before handover. There is an advantage.

That is, the MBS area 100 basically provides a plurality of base stations (BSs) in the same service area. In the same MBS region, MBS parameters are shared so that even if the base station (BS) is moved, the reset procedure is omitted and serviced. These MBS parameters include multicast addresses, ports, encryption keys, and connection identifiers (CIDs).

In addition, in a situation where many users are simultaneously provided with the same multimedia service (eg, news, sports live broadcast, etc.), if the MBS area 100 is used to transmit multimedia data to the multimedia service users, Non It uses less bandwidth (radio resources) than the MBS area. Here, the non-MBS region is a concept including not only the MBS region but also other MBS regions, which will be used as such a concept below.

2 is an explanatory diagram for handover (Intra-MBS area handover) in the MBS area.

The handover in the MBS area has a small delay since it only has a delay by the link-level handover signaling message (IEEE 802.16e handover) exchange 200, as shown in the figure. Has a value (210).

In particular, if all base stations in the MBS region use the same frequency and radio access parameters and provide synchronized data transmission, the delay is " 0 ".

3 is an explanatory diagram for handover (Inter-MBS region handover) between an MBS region and a non-MBS region.

The handover between the MBS area and the non-MBS area includes IEEE802.16e MAC layer handover process 31, trigger process 32, MBS authentication process 33, resource reservation process 34, and security. A key exchange process 35, a multicast distribution tree update process 36, and the like, which correspond to known techniques and will not be described in detail.

The handover between the MBS region and the non-MBS region has a larger delay value than the Intra-MBS region handover (see FIG. 2), as shown in the figure.

As can be seen from FIG. 2 and FIG. 3, the MBS user belonging to the MBS area because the intra-MBS area handover (FIG. 2) has less handover delay than the inter-MBS area handover (FIG. 3). It can be seen that it is advantageous to suppress the case where the UEs handover to another MBS area or a non-MBS area.

4 is an explanatory diagram for a handover type applied to the present invention.

When the MBS area 400 and the non-MBS area 42 are adjacent to each other, the type of handover according to the movement type of the MBS user terminal (mobile terminal) 400 includes (1) in the MBS area 40. (Over Intra MBS Area Handover) ("Case 1"), (2) Handover from MBS Area 40 to Non MBS Area 42 ("Case 2"), (3) Ratio (Non) There is a handover ("Case 3") from the MBS region 42 to the MBS region 40. In the foregoing, the non-MBS area was used as a concept including not only the MBS area but also other MBS areas. The handover types (2) and (3) are simply referred to as "Inter-MBS area handover". It can be said.

5 is an exemplary diagram illustrating a hysteresis control method according to a handover type according to the present invention.

First, a handover parameter as a criterion for performing handover will be described.

The mobile terminal i, which is connected to the serving cell j, triggers a handover to a new target cell k if the following condition (Equation 1) is satisfied.

와

는 셀 k와 셀 j로부터의 수신 전력을 의미한다. 또한

는 셀 j와 k사이의 히스테리시스(Hysteresis) 값을 나타낸다. 그리고, 수신전력

은 일정한 값 이상일 때만 유효하고, 타켓 셀은 충분한 리소스(resource)가 있을 때에만 선택될 수가 있게 된다.Where PBQ is the Power Budget Quantity,

Wow

Denotes the received power from cell k and cell j. Also

Represents the hysteresis value between cells j and k. And the received power

Is valid only when it is above a certain value, and the target cell can be selected only when there are enough resources.

Here, hysteresis is one of the basic elements of the handover parameter that triggers the handover. Changing the value of this hysteresis means changing the trigger of the handover. For example, if a small hysteresis is used, the handover is easily triggered, thereby reducing the probability of outage due to a weakening of the received signal strength, but increasing the ping-pong occurrence rate outside the cell. Conversely, the use of large hysteresis increases the likelihood of outage. Therefore, it is necessary to select a handover parameter considering such a situation.

)를 능동적으로 적용시킴으로써, 전체적인 핸드오버 지연을 감소시키고 무선 대역폭을 효율적으로 사용할 수 있게 한다.The present invention provides a handover parameter to the handover terminals (

By actively applying), the overall handover delay can be reduced and the wireless bandwidth can be used efficiently.

As can be seen from FIG. 2 and FIG. 3, the MBS user belonging to the MBS area because the intra-MBS area handover (FIG. 2) has less handover delay than the inter-MBS area handover (FIG. 3). It is advantageous to suppress the case where the UEs handover to the non-MBS region (including other MBS regions).

를 크게 한다(52). 이러한 핸드오버의 파라미터에 대한 설정(조절) 과정에 대해서는 후술하기로 한다.Therefore, in particular, the present invention, as shown in Figure 5 to suppress the handover (Case2) from the MBS region 40 to another region

Increase (52). The setting (adjustment) process for the parameters of the handover will be described later.

Next, the relationship between the characteristics of the MBS area 40 (FIG. 1) and handover will be described.

The MBS area basically provides a plurality of base stations (BSs) in the same service area. In this same MBS area, MBS parameters (multicast address, port, encryption key, CID, etc.) are shared to provide a BS. Even if it is moved, the reset procedure is skipped and serviced.

For the same reason, it is more efficient for MBS users to service in the MBS area because MBS users are advantageously served in the MBS area than they are serviced in the non MBS area. On the other hand, when the non-MBS user handovers to the MBS area, the wireless parameters are not shared as in the case of the MBS user, and in the case of many MBS users, a certain level of call acceptance cannot be guaranteed. Therefore, it may be advantageous in terms of efficiency of the entire radio resource for non-MBS users to be serviced in the non-MBS area by avoiding the MBS area preferred by the MBS user.

를 작게 한다)(53). 반면에, 본 발명은 MBS 사용자가 MBS 영역에서 비(Non) MBS 영역으로 이동하여 핸드오버 하는 경우(Case 2)에는, 핸드오버 수행을 억제한다(즉,

를 크게 한다)(52).Therefore, in the present invention, when the MBS user moves from the non-MBS area to the MBS area and performs a handover (Case 3), it is recommended to perform the handover (ie,

(53). On the other hand, when the MBS user moves from the MBS area to the non-MBS area and performs handover (Case 2), the present invention suppresses the handover (ie,

To increase) (52).

When the handover user is an MBS user, the present invention is summarized according to the movement type (Fig. 4) as follows.

)을 사용한다(51).[Case 1] is a case where an MBS user moves a cell in the MBS area 40 (Intra MBS area handover). The overall handover delay is short because the MBS user also shares parameters within the MBS area. Therefore, it is not necessary to obtain a gain by adjusting the handover parameter. Therefore, the default value (reference value) (Default

(51).

를 사용한다(52).[Case 2] is a case where the MBS user moves from the MBS area 40 to the non MBS area 42. If a handover occurs in the outside of the MBS region (near the boundary) due to deterioration of the channel state, this is a general disadvantage. Therefore, to prevent this,

(52).

를 사용한다(53). 또한 MBS 영역(40) 안으로 들어가면 "case 2"의 조건이 적용되기 때문에, 핑퐁의 발생률도 감소하게 된다.[Case 3] is a case where the MBS user enters the MBS area 40 from the non MBS area 42. It is necessary to make a handover as soon as possible because it is a case of entering a better condition area. So in this case the small size

(53). In addition, since the condition of "case 2" is applied when entering the MBS region 40, the incidence rate of ping-pong is also reduced.

FIG. 6 is a flowchart illustrating a method for adjusting an adaptive handover parameter in an MBS environment according to the present invention, in which an MBS user terminal is used in [Equation 1] according to three cases of FIG. ) Shows the process of selecting the optimal target cell by applying different values.

In relation to the operation subject of the handover parameter adjustment process, (1) the "base station" may be performed to transmit the determined handover parameter to the corresponding terminal, or (2) the "terminal" that communicates with the base station. It is also possible to determine the type of handover (handover type) by hand and adaptively determine and use the handover parameter.

The present invention is characterized in that the handover parameter is adaptively used through the attributes of the serving cell and the target cell and service information of the terminal. The process of adaptively adjusting the handover parameter is described in detail as follows. .

The terminal / base station analyzes the movement state of the terminal (600) and determines the handover type (600).

If it is determined that the type of handover is a handover ("Case 1") in the MBS region, the terminal / base station maintains the handover parameter at a predetermined reference value (606).

If it is determined that the handover from the MBS area to the non-MBS area ("Case 2"), the terminal / base station changes the handover parameter to a value larger than the reference value (604).

If it is determined that the handover from the non-MBS area to the MBS area ("Case 3"), the terminal / base station changes the handover parameter to a value smaller than the reference value (608).

On the other hand, the method of the present invention as described above can be written in a computer program. And the code and code segments constituting the program can be easily inferred by a computer programmer in the art. In addition, the written program is stored in a computer-readable recording medium (information storage medium), and read and executed by a computer to implement the method of the present invention. The recording medium may include any type of computer readable recording medium.

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

1 is an explanatory diagram for packet transmission in an MBS region;

2 is an explanatory diagram for handover (Intra-MBS area handover) in the MBS area;

3 is an explanatory diagram for handover (Inter-MBS area handover) between an MBS area and a Non-MBS area;

4 is an explanatory diagram for a handover type applied to the present invention;

5 is an exemplary explanatory diagram of a hysteresis control method according to a handover type according to the present invention;

6 is a flowchart illustrating an embodiment of an adaptive handover parameter adjusting method in an MBS environment according to the present invention.

* Explanation of symbols on the main parts of the drawings

40: MBS area 42: non MBS area

400: MBS user terminal

Claims (3)

In the method of adjusting the handover parameter in a multicast and broadcast service (MBS) environment, Determining a handover type according to the movement of the mobile terminal: and A handover parameter according to one of a handover in the MBS region, a handover from the MBS region to the non-MBS region, and a handover from the non-MBS region to the MBS region Step to adjust Handover parameter adjustment method comprising a. The method of claim 1, The adjusting step, If the handover is in the MBS area, maintaining the handover parameter at a predetermined reference value; If the handover is from the MBS area to a non-MBS area, changing the handover parameter to a value greater than the reference value; And If the handover is from the non-MBS area to the MBS area, changing the handover parameter to a value smaller than the reference value Adaptive handover parameter adjustment method comprising a. The method according to claim 1 or 2, The handover parameter is Adaptive handover parameter adjustment method characterized in that the hysteresis.

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