KR101233718B1 - Appratus and method for scanning neighbor base station in a mobile communication system - Google Patents

Abstract

A preferred embodiment of the present invention relates to a handover support for a mobile relay network including a mobile relay and one or a plurality of user terminals communicating with a serving base station through the mobile relay.
To this end, one or more user terminals located in a mobile relay acquire channel parameters corresponding to a radio channel with the serving base station, perform scanning on at least one neighboring base station, and measure scanning results for neighboring base stations, The obtained channel parameter and the measured scanning result are provided to the serving base station or the mobile relay.
And a serving base station or a mobile relay based on the channel parameters estimated by the user terminal and the user terminal and signal strengths measured by one or a plurality of adjacent base stations by the user terminal. Or predict a radio channel quality between a plurality of neighboring base stations.

Description

APPARATUS AND METHOD FOR SCANNING NEIGHBOR BASE STATION IN A MOBILE COMMUNICATION SYSTEM}

A preferred embodiment of the present invention relates to a scanning apparatus and method in a mobile communication system, and more particularly, to an apparatus and method for performing scanning for a neighbor base station in a mobile communication system based on a mobile relay.

In general, a mobile communication network has a mobile station (hereinafter referred to as a 'user terminal') outside a current service area, that is, a serving base station region, and a different service area, that is, a target base station region. Even if it moves to, it supports the procedure to support the seamless service. This procedure is called hand-off, hand-over, roaming, and the like. For convenience of description below, the term 'handover' is collectively used.

Meanwhile, handover in a mobile communication network is performed by cell reselection. The cell reselection is a procedure for the UE to find a target base station (TBS) for network connection or handover.

In general, a scanning technique is applied to a user terminal in order to determine handover by cell reselection or to configure a target base station in a mobile communication system. The scanning technique is a technique for searching for one or more neighbor base stations (NBS) for a specific time by negotiating with a serving base station (SBS).

For example, the user terminal receives a signal transmitted from an adjacent base station by a scanning technique, and based on the received signal, signal strength (RSS) or signal to interference and noise ratio (SINR). ) And so on. For example, a signal transmitted from a neighbor base station for the scanning may be a beacon signal or a preamble signal.

The above-described scanning technique should be basically provided to provide a handover even in a mobile communication network (hereinafter, referred to as a "mobile relay network") equipped with a mobile relay.

The mobile relay is a network element that adds mobility to a fixed relay used for the purpose of improving communication quality of a user terminal connected to a serving base station. The mobile relay may not only be used in multiple places for a limited time but also in an environment where mobility is required. Therefore, the mobile relay is expected to be an element of network deployment of the next generation mobile communication system.

One of the main application network configurations using the mobile relay is a mobile relay network configuration. The mobile relay network refers to a network in which a mobile relay is installed in a vehicle moving at a high speed such as a train or a bus to provide a connection with a serving base station to a user terminal subordinate to or connected to the mobile relay.

Therefore, the mobile relay and the user terminal constituting the mobile relay network have almost similar movement patterns. As a result, user terminals existing in the mobile relay network perform handover at about the same time. In addition, the mobile relay is allocated a radio resource from the serving base station to provide a connection to the subordinate user terminal, it is necessary to perform a handover at a time similar to the user terminal.

In the aforementioned mobile relay network, the scanning technique may not be an essential technique for providing a handover to the mobile relay. For example, if a target base station is already determined, a time for performing a handover is determined, or a handover is determined using only the reception signal quality of the serving base station, scanning technology is not required.

However, in order to predetermine the target base station in the mobile relay network, the operator or operator additionally needs to set or periodically update the coupling relationship between the base stations constituting the mobile relay network. In this case, the self organization network (SON) is difficult, which may impede the spread of the mobile relay.

Therefore, it is common to apply scanning techniques to mobile relay networks. However, when the scanning technique is applied to the mobile relay network, communication between all user terminals and the serving base station that is dependent on or connected to the mobile relay is disconnected in a section in which the mobile relay measures a signal of an adjacent base station.

Therefore, in supporting a handover for a mobile relay network, a scanning scheme is required to minimize the time when communication between a user terminal and a serving base station that is dependent or connected to the mobile relay is lost due to scanning.

The preferred embodiment provides an apparatus and method for estimating the strength of a signal received by a mobile relay from an adjacent base station using received signal information measured by a user terminal constituting the mobile relay network.

In addition, the preferred embodiment provides an apparatus and method for improving the throughput by indirectly measuring the received signal strength of the mobile relay constituting the mobile relay network to reduce the service disconnection time of the user terminal.

In addition, the preferred embodiment provides an apparatus and method for allowing some or all of the user terminals constituting the mobile relay network to obtain the information necessary to predict the scanning result in the mobile relay.

In addition, the preferred embodiment provides an apparatus and method for the serving base station or the mobile relay to predict the channel quality of the neighboring base station based on the information obtained by the user terminal constituting the mobile relay network.

In addition, the preferred embodiment proposes an apparatus and method for determining whether a handover for a mobile relay network is required based on information provided from a user terminal constituting the mobile relay network in a serving base station.

In addition, the present invention proposes an apparatus and method for determining whether a handover for a mobile relay network is required based on information provided from subordinate or connected user terminals in the mobile relay constituting the mobile relay network.

In addition, the present invention proposes an apparatus and method for scheduling a scanning interval so that a plurality of user terminals constituting the mobile relay network performs scanning for neighboring base stations individually or in groups.

In addition, a preferred embodiment proposes a method and system in which a mobile relay can recognize a target base station and a handover time without directly measuring a received signal strength of an adjacent base station.

On the other hand, the purpose according to the preferred embodiment is not limited by the above-mentioned, and other objects not mentioned will be clearly understood or derived from those skilled in the art from the following description.

According to a preferred embodiment of the present invention, a method of performing a handover by a mobile relay in a mobile relay network configured by a mobile relay installed in a mobile unit and communicating with a base station and a plurality of user terminals subordinate to the mobile relay includes: Collecting information on radio channel quality of a serving base station and at least one neighboring base station from a plurality of subordinate user terminals, and based on the collected information on the radio channel quality, the serving base station and the at least one neighboring base station; Estimating radio channel quality for each channel; determining whether there is a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality; and when the target base station exists, Handover to the serving base station to the target base station It comprises the step of requesting.

In addition, a serving base station supports a handover for the mobile relay in a mobile relay network configured by a mobile relay installed in a mobile according to a preferred embodiment and communicating with a base station and a plurality of user terminals subordinate to the mobile relay. The method may include collecting information on a radio channel quality of a serving base station and at least one neighboring base station from the plurality of subordinate user terminals, and based on the collected information on the radio channel quality. Estimating a radio channel quality between a serving base station and a radio channel quality between the mobile relay and each neighboring base station; and a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality. Determining whether or not the target base station is When to relocate the mobile relay comprises the step of indicating a handover to the target base station.

In addition, the mobile station is installed in the mobile according to the preferred embodiment and performs a handover from the serving base station to the target base station in the mobile relay network consisting of a mobile relay for communication with the base station and a plurality of user terminals subordinate to the mobile relay The mobile relay includes a measurement result receiver configured to collect information about radio channel quality of the serving base station and at least one neighboring base station from the plurality of subordinate user terminals, and the serving based on the collected radio channel quality information. A signal estimator for estimating radio channel quality for each base station and the at least one neighboring base station, and determining whether there is a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality; , When the target base station exists, the serving And a handover controller for requesting a base station for handover to the target base station.

A serving base station supporting handover for the mobile relay in a mobile relay network configured by a mobile relay configured to communicate with a base station and a plurality of user terminals subordinate to the mobile relay, installed in a mobile according to a preferred embodiment. Is a measurement result receiver configured to collect information on radio channel quality of a serving base station and at least one neighboring base station from the plurality of subordinate user terminals, the mobile relay and the based on the collected radio channel quality information. A signal estimator for predicting radio channel quality between a serving base station and radio channel quality between the mobile relay and each neighboring base station, and a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality; Determine if it exists, the target base When this is present, it comprises a relay to the mobile hand-over control part for instructing the handover to the target base station.

In a preferred embodiment, by minimizing the time required for scanning of neighboring base stations for handover in a mobile relay network, it is possible to improve service disconnection and resource use efficiency.

Meanwhile, various other effects will be directly or implicitly disclosed in the detailed description according to the embodiment of the present invention to be described later.

1 illustrates the overall flow for determining handover of a mobile relay network according to a preferred embodiment;
2 illustrates an example of an overall operation for determining handover of a mobile relay network in a mobile communication system according to an embodiment of the present disclosure;
3 illustrates another example of an overall operation for determining handover of a mobile relay network in a mobile communication system according to a preferred embodiment;
4 is a diagram illustrating a configuration of reporting a measurement result for handover determination of a mobile relay network in a user terminal according to an exemplary embodiment;
5 is a diagram illustrating a configuration of determining a handover of a mobile relay network based on a measurement result from a user terminal in a serving base station or mobile relay according to a preferred embodiment;
FIG. 6 is a diagram illustrating a detailed configuration of the signal estimator illustrated in FIG. 5.

In the following description of the preferred embodiment, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the technical gist, the detailed description thereof will be omitted.

According to a preferred embodiment of the present invention, a method for determining whether a handover of the mobile relay network is required based on channel parameters for a serving base station estimated by a user terminal in the mobile relay network and received signal strengths of one or more neighboring base stations is required. Prepare.

To this end, a user terminal belonging to a mobile relay network estimates its channel parameter using a broadcast signal transmitted from a serving base station. In addition, the user terminal performs scanning on one or a plurality of neighboring base stations. The estimated channel parameter and the result obtained by performing the scanning are transmitted to a subject (serving base station or mobile relay) to determine handover of the mobile relay network.

The user terminal preferably sets the time for scanning to the same time by negotiation with the serving base station. In addition, when more user terminals than a threshold value are located in the mobile relay, the user terminal participating in the signal strength estimation for neighboring base stations can be selected among the user terminals located in the mobile relay.

Meanwhile, the subject (serving base station or mobile relay) to determine the handover of the mobile relay network estimates the channel parameters of the mobile relay, and uses the estimated channel parameters of the mobile relay, the channel parameters reported by the user terminal, and the scanning result. The signal quality of each neighboring base station in the mobile relay is estimated.

First, terms to be used in defining a preferred embodiment corresponding to the above summary are defined as follows.

Access technology is an interface technology that connects a user terminal with a wireless network or a wired network. In particular, radio access technology (RAT) is an air interface technology that connects a user terminal with a base station or an access point (AP). For example, cellular access technology defined by 3GPP (3rd Generation Partnership Project), 3GPP2, etc., Wireless Local Area Network (WLAN) technology defined by IEEE 802.11, Mobile Wireless MAN (Metropolitan Area Network) technology defined by IEEE 802.16e, IEEE 802.15 PAN (Personal Area Network) technology is defined.

A relay is a network element used to improve connectivity between a user terminal and a base station, and is used to extend a service area or to improve a transmission speed.

The mobile relay provides the mobility of the mobile relay network while playing the same role as a normal relay in the mobile relay network. For example, it is installed in a moving object such as a bus, a train, a ship, and serves to connect one or more user terminals existing in the moving object and a serving base station.

The mobile relay network refers to a mobile network constituted by one or more user terminals and mobile relays existing in a certain area having a similar channel environment. For example, a mobile network implemented for moving objects such as buses, trains, ships, etc. is called a mobile relay network.

A user terminal (or mobile station) means any terminal device that can communicate using radio resources. A representative example may be a mobile phone, a PDA, a notebook computer, a desktop PC having a wireless LAN, and the like.

A subordinate user terminal (or subordinate mobile station) refers to a user terminal connected to a base station through a mobile relay among user terminals providing a service to a user. In a particularly preferred embodiment, it refers to a user terminal that configures a mobile relay network and is connected to a serving base station through the mobile relay.

The serving base station refers to a base station to which subordinate user terminals are connected through a mobile relay. The serving base station may determine the need for a handover of the mobile relay network, and may instruct a handover to the mobile relay network through this.

The neighbor base station means a base station that exists in the vicinity of the serving base station and may be a handover target of the mobile relay network. That is, the base station to be scanned.

The target base station means a base station determined as a target to be handed over through a cell reselection process among neighboring base stations.

와 같이 지수함수로 정의할 경우, 경로 손실 상수 인

와 경로 손실 지수

가 채널 파라미터가 될 수 있다. 또한 느린 페이딩을 로그 분포로 표현할 경우의 평균과 분산 및 빠른 페이딩을 레일리 분포로 표현할 경우의 평균과 분산 또한 채널 파라미터가 될 수 있다.Channel parameters are parameters used to define the characteristics of a wireless channel. For example path loss

When defined as an exponential function,

And path loss index

May be a channel parameter. In addition, the average and variance of expressing slow fading in logarithmic distribution and the average and variance of expressing fast fading in Rayleigh distribution can also be channel parameters.

Scanning is defined as a process in which a user terminal requesting mobility and a mobile relay measure signal strengths of adjacent base stations in order to perform handover. In this case, in addition to measuring the signal strength in the scanning process, it is possible to additionally obtain the frame structure, radio resource information, connection information, etc. of the neighboring base station.

The scanning result information refers to information obtained by the subordinate user terminal through scanning of a neighbor base station. For example, the scanning result information may be signal strength of an adjacent base station.

Signal strength may be defined as a quality of a radio channel between a base station and a user terminal or a base station and a mobile relay, and a mobile relay and a user terminal. For example, when a user terminal receives a signal transmitted from a base station, a signal to interference plus noise ratio (SINR) considering a received signal strength index (RSSI) and interference from an adjacent base station Etc.

Scanning parameters are defined as time information required to perform scanning and information required to perform scanning. That is, when the user terminal or the mobile relay has only one receiver, it does not receive service from the serving base station while scanning the neighbor base station. As a result, in order to overcome the loss of packets and control information that are not received, the serving base station and the user terminal or the mobile relay perform scanning for a time negotiated beforehand. As such, the information provided from the serving base station to the user terminal in order to negotiate a time for performing scanning may be a scanning parameter.

Terms used in the description to be described below are terms defined in consideration of functions according to a preferred embodiment, which may vary according to intention or custom of a user or an operator. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment. Further, if it is determined that the gist of the present invention may be unnecessarily blurred, detailed description thereof will be omitted.

1 shows an overall flow for determining handover of a mobile relay network according to a preferred embodiment.

Referring to FIG. 1, the slave user terminal reports the estimated channel parameter and the result obtained through the scanning process to the serving base station or the mobile relay (step 110).

To this end, the slave user terminal estimates the channel parameter in consideration of the reception strength, channel characteristics, etc. of the signal (eg, reference signal) received from the serving base station. In this case, the channel parameter is a parameter defining the characteristics of the radio channel between the serving base station and the subordinate user terminal as defined above, and may be a channel gain, a path loss constant, a path loss index, and the like.

In addition, the slave user terminal performs a scanning process for at least one base station (adjacent base station) adjacent to the serving base station. The time interval for performing the scanning process may be designated by negotiation with a serving base station.

The slave user terminal may measure the received signal strength for each neighboring base station by performing the scanning process. Therefore, the scanning result to be reported to the serving base station or the mobile relay may be information on received signal strength for each neighboring base station.

The serving base station or the mobile relay determines whether handover of the mobile relay network is necessary using the channel parameters and the scanning result reported by the subordinate user terminal (step 120).

In order to determine the need for handover of the mobile relay network, the serving base station or the mobile relay requires prediction of a radio channel condition between the mobile relay and each neighboring base station. In order to predict the radio channel condition between the mobile relay and each neighboring base station, channel parameters and scanning results reported by subordinate user terminals and channel quality indicator (CQI) information between the serving base station and the mobile relay are used. Therefore, if the prediction of the radio channel condition between the mobile relay and each neighboring base station is made by the serving base station, the CQI information estimated by the mobile relay should be further reported to the serving base station. It is also possible for the mobile relay to report the channel parameter estimated by the CQI information to the serving base station instead of the CQI information.

The serving base station or the mobile relay uses the channel parameters reported from the subordinate user terminals and the scanning result (received signal strength) to predict the radio channel condition between the mobile relay and each neighboring base station. Estimate the average value of slow fading.

The received signal strength between the mobile relay and the neighboring base station is estimated based on the estimated log distance, the average value of the slow fading, and the estimated channel parameter of the mobile relay. In this case, the estimated channel parameter of the mobile relay may be estimated by the mobile relay or the serving base station. The estimated parameter of the mobile relay means a channel parameter estimated based on the signal strength of the serving base station measured by the mobile relay.

The serving base station or the mobile relay determines whether handover of the corresponding mobile relay network is necessary using the estimated received signal strength. If it is determined that handover of the mobile relay network is required, the serving base station or the mobile relay selects one of the neighboring base stations as a target base station to which the mobile relay network is to be handed over.

2 illustrates an example of an overall operation for determining handover of a mobile relay network in a mobile communication system according to an exemplary embodiment. That is, in FIG. 2, the serving base station determines a handover of the mobile relay network using the received signal information measured by the user terminal.

Referring to FIG. 2, a user terminal in a mobile relay network receives a signal transmitted from a serving base station (step 210). In this case, the signal received by the user terminal may be a reference signal for measuring the quality of a radio channel corresponding to the downlink.

The user terminal measures a received signal strength of the received signal, and the measured received signal strength is expressed by Equation 1 below.

는

번째 사용자 단말의 채널 이득이고,

는

번째 사용자 단말의 느린 페이딩을 의미하고,

는 서빙 기지국과

번째 사용자 단말의 거리를 의미하고,

는

에서의 경로 손실을 의미하며,

는 빠른 페이딩의 경로 별 분산 전력을 의미한다.here

The

Channel gain of the user terminal,

The

Slow fading of the user terminal,

With the serving base station

Means the distance of the user terminal,

The

Path loss in,

Means distributed power by path of fast fading.

는 하기 <수학식 2>과 같은 특성을 가진다.And distributed power for each path of the fast fading.

Has the same characteristics as Equation 2 below.

는 1로 수렴됨을 확인할 수 있다.That is, according to the definition of Equation 2, the distributed power for each path of fast fading is

It can be seen that converges to 1.

에서의 경로 손실인

는 하기 <수학식 3>과 같이 정의할 수 있다.And

Path loss in

May be defined as in Equation 3 below.

는

번째 사용자 단말의 경로 손실 지수이며,

는

번째 사용자 단말의 경로 손실 상수를 의미한다. here

The

Path loss index of the first user terminal,

The

The path loss constant of the first user terminal.

On the other hand, the signal strength used when performing the handover is measured by considering only path loss and slow fading in order to suppress unnecessary handover due to a sudden signal change.

Accordingly, the received signal strength of the serving base station for removing signal dispersion due to fast fading may be represented by Equation 4 below.

번 측정한 수신 신호 세기는 하기 <수학식 5>로 나타낼 수 있다.Meanwhile, based on Equation 4 for channel parameter estimation

The received signal strength measured once may be represented by Equation 5 below.

는

번째 사용자 단말에 의해

번 측정한 수신 신호 세기 행렬이고,

는

번째 사용자 단말에 의해 수신 신호 세기를

번 측정할 시의 채널 특성 행렬이고,

는

번째 사용자 단말에 의해 수신 신호 세기를

번 측정함에 상응하는 채널 파라미터 행렬이며,

는

번째 사용자 단말에 의해 수신 신호 세기를

번 측정함에 상응하는 느린 페이딩 요소 행렬이다.here

The

By the first user terminal

Is the received signal strength matrix,

The

Received signal strength by the first user terminal

Is the matrix of channel characteristics at times

The

Received signal strength by the first user terminal

Is the channel parameter matrix corresponding to times

The

Received signal strength by the first user terminal

It is a slow fading element matrix corresponding to one measurement.

Equation 5 may be expressed as Equation 6 below.

는

번째 사용자 단말에서의 채널 이득을 의미하고,

는

번째 사용자 단말에서 채널 이득과 경로 손실 상수 간의 차이로 정의된 채널 파라미터 중 하나이며,

는

번째 사용자 단말에서의 느린 페이딩 요소를 의미한다.here

The

Channel gain in the user terminal,

The

One of the channel parameters defined as the difference between the channel gain and the path loss constant at the first user terminal,

The

It means a slow fading element in the first user terminal.

,

는 수신 신호 세기에 대한 추정을 통해 알 수 있는 정보이다. In <Equation 5> and <Equation 6>

,

Is information that can be known through estimation of received signal strength.

를 제거함으로써, 하기 <수학식 7>에 의해 추정할 수 있다.Accordingly, the channel parameter to be finally estimated is expressed by Equation 5 through Least Square Estimation (LSE).

By eliminating the equation, it can be estimated by Equation 7 below.

는

로 정의된다. 여기서

는

를 의미한다.remind

The

. here

The

.

As described above, the user terminal may finally estimate a channel parameter corresponding to the radio channel with the serving base station.

The user terminal periodically or aperiodically scans at least one neighboring base station (step 220). For example, in order to perform the scanning, the user terminal may acquire a scanning parameter through a phenomenon with a serving base station. In this case, the scanning parameter may be set such that all user terminals subordinate to the mobile relay perform scanning at the same time.

The user terminal obtains the result through scanning based on the scanning parameter. For example, the scanning result may be received signal strength for each neighboring base station.

The user terminal transmits the previously estimated channel parameter and the scanning result to the serving base station (step 230).

The mobile relay generates CQI information based on the signal received from the serving base station, and transfers the generated CQI information to the serving base station (step 240). In addition, the mobile relay may estimate a channel parameter by Equation 7 based on the received signal strength of the signal received from the serving base station, and transfer the estimated channel parameter to the serving base station.

The serving base station estimates the received signal strength between the mobile relay and each neighboring base station using channel parameters and scanning results transmitted from all or some user terminals in the mobile relay network and CQI information or channel parameters delivered from the mobile relay. do. The UE determines whether to handover the mobile relay network based on the received signal strength estimated for each neighbor BS.

In more detail, the reception signal strength of each neighboring base station, which the serving base station receives from all or some user terminals in the mobile relay network, may be defined by Equation 8 below.

은

번째 사용자 단말에 의해 측정된

번째 인접 기지국의 수신 신호 세기를 의미하고,

은

번째 사용자 단말에 의해 추정된 채널 이득 (

)과 경로 손실 상수 (

)의 차이 (

)를 의미하며,

은

번째 사용자 단말에 의해 측정된

번째 인접 기지국의 느린 페이딩을 정의한다.here

silver

Measured by the first user terminal

The received signal strength of the first neighboring base station,

silver

Channel gain estimated by the first user terminal (

) And path loss constants (

) Difference

),

silver

Measured by the first user terminal

Slow fading of the first neighbor base station is defined.

을 사용자 단말에 의해 전달된 스캐닝 결과에 의해 획득할 수 있으며,

와

은 사용자 단말에 의해 전달된 채널 파라미터에 의해 획득할 수 있다.The serving base station is

Can be obtained by the scanning result delivered by the user terminal,

Wow

Can be obtained by the channel parameter delivered by the user terminal.

Therefore, in order to estimate the logarithmic distance between the mobile relay and the adjacent base station and the average value of the slow fading, the serving base station is developed by the following equation (9).

The serving base station may estimate the logarithmic distance and the slow fading average value between the mobile relay and the neighboring base station by Equation 9 through least squares estimation.

The serving base station estimates the received signal strength for each neighboring base station in the mobile relay using the log distance between the mobile relay and the neighboring base station estimated as described above, the slow fading average value, and the estimated channel parameter of the mobile relay. The estimated channel parameter of the mobile relay can be estimated by the serving base station by Equation 7 using the CQI information received from the mobile relay. Otherwise it may be estimated by the mobile relay and delivered to the serving base station.

Estimation of the received signal strength for each neighboring base station in the serving base station is made by Equation 10 below.

와

는 이동 릴레이의 추정된 채널 파라미터이고,

는 가우시안 분포에서 임의로 선택되는 이동 릴레이의 느린 페이딩 요소이다. 그리고

는 인접 기지국의 인덱스로써, 1 내지 m의 범위를 가진다.here

Wow

Is the estimated channel parameter of the mobile relay,

Is a slow fading component of the mobile relay randomly selected from the Gaussian distribution. And

Is an index of a neighbor base station and ranges from 1 to m.

로 선택되는 가우시안 분포의 평균 (

)과 분산 (

)은 하기 <수학식 11>로 정리된다.remind

Mean of Gaussian distribution selected by

) And variance (

) Is summarized by Equation 11 below.

는 상기 <수학식 9>에 의해 추정된 느린 페이딩 평균 값이고,

는

번째 사용자 단말에서

(= 1......m) 번째 인접 기지국에 대해 측정한 수신 신호 세기를 의미한다.here

Is a slow fading average value estimated by Equation 9,

The

On the first user terminal

(= 1 ...... m) Means the received signal strength measured for the n th neighbor base station.

The serving base station determines whether handover for the mobile relay network is necessary based on the received signal strength estimated for each neighboring base station as described above. If it is determined that handover for the mobile relay network is necessary, the best neighboring base station among the neighboring base stations is selected as a target base station using the received signal strength estimated for each neighboring base station.

If the serving base station determines that a handover of the mobile relay network is necessary and selects a target base station, the serving base station transmits a handover start message indicating a handover to the target base station to the mobile relay (step 250).

When the handover start message is transmitted from the serving base station, the mobile relay performs a handover procedure from the serving base station to the target base station.

3 illustrates another example of an overall operation for determining handover of a mobile relay network in a mobile communication system according to an exemplary embodiment. That is, FIG. 3 illustrates a procedure in which the mobile relay determines the handover of the mobile relay network using the received signal information measured by the user terminal.

Referring to FIG. 3, a user terminal in a mobile relay network receives a signal transmitted from a serving base station (step 310). In this case, the signal received by the user terminal may be a reference signal for measuring the quality of a radio channel corresponding to the downlink.

The user terminal measures the received signal strength of the received signal by Equation (4). The channel parameter is estimated using Equation 7 based on the measured received signal strength and the radio channel characteristic of the serving base station. In this case, the estimated channel parameter corresponds to a radio channel between the serving base station and the user terminal.

The user terminal periodically or aperiodically scans at least one neighboring base station (step 320). For example, in order to perform the scanning, the user terminal may acquire a scanning parameter through a phenomenon with a serving base station. In this case, the scanning parameter may be set such that all user terminals subordinate to the mobile relay perform scanning at the same time.

The user terminal obtains the result through scanning based on the scanning parameter. For example, the scanning result may be received signal strength for each neighboring base station.

The user terminal transmits the previously estimated channel parameter and the scanning result to the mobile relay (step 330).

The mobile relay estimates a channel parameter by Equation 7 based on the received signal strength of the signal received from the serving base station.

The serving base station estimates the received signal strength for each neighboring base station by using the channel parameter and the scanning result and the estimated channel parameter transmitted from all or some user terminals in the mobile relay network.

To this end, the mobile relay uses the channel parameters and scanning results transmitted from all or some user terminals in the mobile relay network as defined in Equation 9 to determine the log distance and the slow fading between the mobile relay and the adjacent base station. Estimate the average value.

The mobile relay estimates the received signal strength of each neighboring base station by using the estimated log distance between the mobile relay and the neighboring base station, a slow fading average value, and a channel parameter estimated by itself according to the serving base station. That is, the mobile relay estimates the received signal strength of each neighboring base station by Equation (10).

The mobile relay determines whether handover for the mobile relay network to which it belongs is based on the received signal strength estimated for each neighboring base station as described above. If it is determined that handover for the mobile relay network is necessary, the best neighboring base station among the neighboring base stations is selected as a target base station using the received signal strength estimated for each neighboring base station.

If the mobile relay determines that a handover of the mobile relay network is necessary and selects a target base station, the mobile relay transmits a handover request message to the mobile relay requesting a handover to the target base station (step 350).

If the handover response message is transmitted from the serving base station in response to the handover request message, the mobile relay performs a handover procedure from the serving base station to the target base station (step 350).

4 illustrates a configuration of reporting a measurement result for handover determination of a mobile relay network in a user terminal according to an exemplary embodiment.

Referring to FIG. 4, the location measuring unit 410 estimates the distance between the serving base station and the user terminal based on the signal received from the serving base station. The estimated distance information is provided to the channel parameter estimator 430.

The signal measuring unit 420 measures the strength of the signal received from the serving base station, and provides the measured received signal strength to the channel parameter estimating unit 430. In addition, the signal measuring unit 420 scans at least one neighboring base station in a predetermined time interval, and provides the received signal strength of each neighboring base station according to the scanning to the measurement result transmitter 440 as a scanning result. do. For example, the predetermined time interval may be determined by a scanning parameter obtained through negotiation with a serving base station.

The channel parameter estimator 430 estimates a channel parameter using distance information provided from the position measuring unit 410 and received signal strength information of a serving base station provided from the signal measuring unit 420. In this case, the channel parameter may be estimated by Equation 7 defined above. The channel parameter estimator 430 provides the estimated channel parameter to the measurement result transmitter 440.

The measurement result transmitter 440 transfers the measurement result including the received signal strength for each adjacent base station provided from the signal measuring unit 420 and channel parameter information provided from the channel parameter estimator 430 to a serving base station or a mobile relay. send.

5 illustrates a configuration of determining a handover of a mobile relay network based on a measurement result from a user terminal in a serving base station or mobile relay according to a preferred embodiment.

Referring to FIG. 5, the measurement result receiver 510 receives measurement results transmitted by all or some user terminals existing in the mobile relay network. For example, the measurement result includes received signal strength and channel parameter information for each adjacent base station. The received signal strength and channel parameter information for each neighboring base station are measured or estimated by the user terminal.

The measurement result receiver 510 extracts an estimated channel parameter and a measurement received signal strength from the measurement result. The extracted estimated channel parameter and the measured received signal strength are provided to the signal estimator 512.

The signal estimator 512 estimates the received signal strength of each neighboring base station in the mobile relay by using the estimated channel parameter and the measured signal strength result provided from the measurement result receiver 510. The received signal strength for each neighboring base station can be estimated by Equation 10 defined above. The signal estimator 512 provides the estimated received signal strength for each neighboring base station to the handover controller 514.

The handover controller 514 determines whether there is a received signal strength that satisfies the handover execution condition among the received signal strengths of the neighboring base stations estimated by the signal estimator 512. If the received signal strength satisfying the handover execution condition exists, it is determined that handover of the mobile relay network is necessary.

If the handover control unit 514 determines that handover of the mobile relay network is necessary, the handover control unit 514 selects a target base station for handover by the mobile relay network. The target base station may be an adjacent base station corresponding to the received signal strength that satisfies the handover execution condition.

If there are a plurality of received signal strengths satisfying the handover execution condition, the handover control unit 514 selects an adjacent base station corresponding to the best (eg, the largest) received signal strength among the plurality of received signal strengths. Can be selected as the target base station.

The handover control unit 514 transmits a handover start message or a handover request message to perform a handover to the previously selected target base station. If the serving base station determines whether to perform the handover, the handover control unit 514 transmits a handover start message to the mobile relay. Otherwise, if the mobile relay determines whether to perform the handover, the handover control unit 514 transmits a handover request message to the mobile relay.

6 shows a detailed configuration of the signal estimator 512 shown in FIG.

Referring to FIG. 6, the estimated channel parameter provided by the measurement result receiver 510 is input to the channel matrix unit 610, and the measurement received signal strength is input to the measurement matrix unit 612.

The channel matrix unit 610 estimates a path loss matrix and channel gain information based on the estimated channel parameter. The estimated path loss matrix is provided to the estimator 614, and the estimated channel gain information is provided to the measurement matrix unit 612.

The measurement matrix unit 612 calculates a difference between the measured received signal strength and the channel gain information provided from the channel matrix unit 610, and provides the calculated difference value to the estimator 614.

The estimator 614 estimates a distance between the mobile relay and each neighboring base station by using the path loss matrix provided from the channel matrix unit 610 and the measurement result matrix provided from the measurement matrix unit 612. The estimator 614 calculates slow fading information for each adjacent base station by using a path loss matrix provided from the channel matrix unit 610 and a measurement result matrix provided from the measurement matrix unit 612.

The estimator 614 provides the estimated strength of each neighboring base station and the slow fading information calculated for each neighboring base station to the signal strength generator 616.

The signal strength generator 616 estimates the received signal strength of each neighboring base station in the mobile relay by using Equation 10 and Equation 11 defined above. The received signal strength estimated for each neighboring base station is provided to the handover controller 514 of FIG. 5.

On the other hand, while the preferred embodiment has been shown and described, it is not limited to the specific embodiment described above, it should be understood by those of ordinary skill in the art without departing from the technical gist of the claims. Of course, various variations and modifications are possible. And these modified implementations should not be understood individually from the technical spirit or prospect of the present invention. In addition, the technical idea proposed by the preferred embodiment should be understood only by the claims described below, and all equivalent or equivalent modifications thereof will belong to the scope of the proposed technical idea.

For example, in determining the handover of the mobile relay network, only some user terminals of the subordinate user terminals may transmit the measurement result messages to the serving base station or the mobile relay in order to reduce the number of measurement result messages delivered by the subordinate user terminals. Can be. In addition, the serving base station groups subordinate user terminals in order to reduce the estimated time interval when the moving speed of the mobile relay increases, and performs scanning for neighboring base stations at different times for each group.

Claims (20)

In the method of performing the handover in the mobile relay network in the mobile relay network is configured by a mobile relay is installed in a mobile body and performs communication with a base station and a plurality of user terminals subordinate to the mobile relay,
Collecting information on radio channel quality of a serving base station and at least one neighboring base station from the plurality of subordinate user terminals;
Estimating radio channel quality for each of the serving base station and the at least one neighboring base station based on the collected information about the radio channel quality;
Determining whether there is a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality;
Requesting handover to the serving base station from the serving base station when the target base station exists. The method of claim 1,
The collected information about the quality of the radio channel includes a channel parameter defining a radio channel characteristic between the serving base station and the user terminal and a strength of a signal received from the at least one neighboring base station at the user terminal. How to perform handover in relay. The method of claim 1,
The collected information about the quality of the radio channel is a method of performing a handover in a mobile relay, characterized in that some or all of the subordinate user terminals are measured at the same time specified by the serving base station. The method of claim 1,
The collected information about the radio channel quality is classified into a plurality of subordinate user terminals into a plurality of groups, and the handover is performed in the mobile relay, characterized in that measured at different times for each group by the serving base station. Way. delete delete A method of supporting a handover for a mobile relay by a serving base station in a mobile relay network configured by a mobile relay installed in a mobile unit and communicating with a base station and a plurality of user terminals subordinate to the mobile relay,
Collecting information on radio channel quality of a serving base station and at least one neighboring base station from the plurality of subordinate user terminals;
Estimating a radio channel quality between the mobile relay and the serving base station and a radio channel quality between the mobile relay and each neighboring base station based on the collected information about the radio channel quality;
Determining whether there is a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality;
And instructing the mobile relay handover to the target base station when the target base station exists. The method of claim 7, wherein
The collected information about the radio channel quality includes a channel parameter defining a radio channel characteristic between the serving base station and the user terminal, and a strength of a signal received from the at least one neighboring base station at the user terminal. Method for supporting handover at the base station. The method of claim 7, wherein
The collected information about the quality of the radio channel is a handover support method in a serving base station, characterized in that some or all of the subordinate user terminals are measured at the same time specified by the serving base station. The method of claim 7, wherein
The collected information about the quality of the radio channel is classified into a plurality of subordinate user terminals into a plurality of groups, and the handover support in the serving base station characterized in that measured by the serving base station differently for each group. Way. delete delete A mobile relay installed in a mobile body and performing a handover from a serving base station to a target base station in a mobile relay network configured by a mobile relay configured to communicate with a base station and a plurality of user terminals subordinate to the mobile relay,
A measurement result receiver configured to collect information on radio channel quality of the serving base station and at least one neighboring base station from the plurality of subordinate user terminals;
A signal estimator for predicting radio channel quality for each of the serving base station and the at least one neighboring base station based on the collected information about the radio channel quality;
It is determined whether there is a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality, and when the target base station exists, requesting the serving base station to handover to the target base station. A mobile relay comprising a handover control unit. The method of claim 13,
The collected information about the quality of the radio channel includes a channel parameter defining a radio channel characteristic between the serving base station and the user terminal and a strength of a signal received from the at least one neighboring base station at the user terminal. relay. The method of claim 13,
The collected information about the radio channel quality is a mobile relay, characterized in that some or all of the subordinate user terminals are measured at the same time specified by the serving base station. delete A serving base station supporting a handover for a mobile relay in a mobile relay network configured by a mobile relay installed in a mobile unit and communicating with a base station and a plurality of user terminals subordinate to the mobile relay,
A measurement result receiver configured to collect information on radio channel quality of a serving base station and at least one neighboring base station from the plurality of subordinate user terminals;
A signal estimator for predicting radio channel quality between the mobile relay and the serving base station and radio channel quality between the mobile relay and each neighboring base station based on the collected information about the radio channel quality;
It is determined whether there is a target base station to perform handover among the at least one neighboring base station based on the predicted radio channel quality, and when the target base station exists, the mobile relay is instructed to handover to the target base station. A serving base station comprising a handover control unit. 18. The method of claim 17,
The collected information about the radio channel quality includes a channel parameter defining a radio channel characteristic between the serving base station and the user terminal, and a strength of a signal received from the at least one neighboring base station at the user terminal. Base station. 18. The method of claim 17,
The collected base station information is characterized in that some or all of the subordinate user terminals are measured at the same time specified by the serving base station. 18. The method of claim 17,
The collected base station information is characterized in that the plurality of subordinate user terminals are classified into a plurality of groups, and measured by the serving base station at different times for each group.

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