KR20120084592A - Apparatus and method for operating in coordinated multiple point in wireless communication system - Google Patents

Abstract

The present specification provides an apparatus and method for operating in a multi-point manner linked to in a wireless communication system.
The present specification provides a method for measuring a channel related to a first link between a first base station and a terminal, transmitting information about the first link to a second base station, and based on an associated multi-point scheme. Receiving link configuration information used to set a primary cell link from the first base station; and setting the first link as the primary cell link based on the link configuration information, and between the second base station and the terminal. A method comprising setting a second link as a secondary cell link is disclosed.
According to the present specification, when a specific base station is designated as a primary base station or a specific base station as a secondary base station among linked base stations in an associated multipoint scheme, scheduling conflicts due to scheduling ambiguity may be resolved.

Description

Apparatus and method for multi-point operation in a wireless communication system {APPARATUS AND METHOD FOR OPERATING IN COORDINATED MULTIPLE POINT IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to wireless communication, and more particularly, to an apparatus and method for operating in a multi-point method linked to a wireless communication system.

In general, in a multi-cellular communication system, each cell does not consider other cells, but the cell boundary when communication is performed between the base station and the terminal while maintaining frequency reuse '1' in the same time and frequency band. The closer to the terminal, the worse the performance due to signal distortion and interference from other cells due to power reduction of the received signal.

In order to overcome the performance deterioration caused by power reduction and interference, various techniques have been studied so far, and one of them has been discussed as a coordinated multiple point (CoMP) scheme between multiple cells or between multiple transmitters. . The linked multipoint scheme is also referred to as a cooperative transmission and reception scheme. The linked multi-point scheme widely refers to a method in which different base stations or multiple transmission terminals communicate with the same terminal. That is, a plurality of base stations share information about a cell, and uses this to perform downlink transmission or uplink reception. The associated multipoint scheme includes a plurality of base stations linked together to perform downlink or uplink scheduling for efficient radio resource distribution.

This method is used to transmit power gain and signal sensitivity to terminals whose signal strength is weak compared to terminals in the cell center region or in a region where signal reception sensitivity is poor in a cell-edge region or an area where signal reception sensitivity is poor. Can improve the transmission rate of the entire system by effectively eliminating the effects of interference. However, according to this approach, very complicated scheduling may be required in a crowded area where a large number of users are connected. In addition, scheduling efficiency may decrease due to a delay occurring in a process in which a plurality of base stations share information about a plurality of cells, or performance degradation of a system may occur due to inadequate scheduling.

An object of the present invention is to provide an apparatus and method for preselecting some base stations as secondary base stations and other base stations as main base stations in an associated multipoint scheme.

Another technical problem of the present invention is to provide an apparatus and method for entering a main base station in a linked multipoint manner in a potentially determined environment.

Another technical problem of the present invention is to provide a terminal and a base station operating in an associated multi-point method.

Another technical problem of the present invention is to provide an apparatus and method for establishing a primary cell link or a secondary cell link in an associated multi-point method.

Another technical problem of the present invention is to provide an apparatus and method for selecting a main base station among a plurality of base stations in an associated multi-point method.

Another technical problem of the present invention is to provide an apparatus and method for preferentially performing scheduling to a main base station in an associated multipoint scheme.

According to an aspect of the present invention, a method for measuring a channel on a first link between a first base station and a terminal, transmitting information on the first link to a second base station, and coordinated multipoints receiving link configuration information from the first base station, the link setting information used to set the first link as a primary cell link based on a multiple point scheme, and the first link based on the link configuration information. Setting as the primary cell link, and setting a second link between the second base station and the terminal as a secondary cell link (secondary cell link).

The primary cell link has a priority of scheduling with respect to the secondary cell link, and the first base station, the second base station, and the terminal operate in the associated multipoint scheme.

According to another aspect of the present invention, a channel measurement unit for measuring a channel related to a first link between a first base station and a terminal, and a link setting used to set the first link as a primary cell link based on an associated multipoint scheme. A downlink receiving unit for receiving information or a handover command from the first base station, and setting the first link as the main cell link based on the link setting information, and a second link between a second base station and the terminal It provides a terminal including a link setup performing unit for setting the secondary cell link to the uplink transmitter for transmitting information about the first link to the second base station.

The primary cell link has a priority of scheduling with respect to the secondary cell link, and the first base station, the second base station, and the terminal operate in the associated multipoint scheme.

According to another aspect of the present invention, transmitting a reference signal used for measurement of a channel related to a first link to a terminal, and is used to set the first link as a primary cell link based on an associated multipoint scheme. And transmitting link setting information to the terminal, and transmitting a handover command to the terminal to set the first link as the main cell link based on the link setting information.

The primary cell link has a priority of scheduling with respect to the secondary cell link.

According to another aspect of the present invention, the link setting information or the link used to set the first link as the primary cell link based on a reference signal or an associated multipoint scheme used for measuring a channel related to the first link. A downlink transmitter for transmitting a handover command for setting the first link to the primary cell link to the terminal based on configuration information, and a link configuration controller for controlling the primary cell link to be set in the terminal; It provides a main base station.

In a linked multipoint scheme, designation of a specific base station as a primary base station or a specific base station as a secondary base station among linked base stations may solve scheduling conflicts due to scheduling ambiguity.

1 is a block diagram illustrating a wireless communication system.
2 is a diagram illustrating a communication system supporting an associated multipoint scheme.
3 is a diagram illustrating an example of a system operation scenario according to an associated multi-point method.
4 and 5 are examples illustrating scheduling of a plurality of eNBs operating in the multi-point method associated with FIG. 3.
6 and 7 illustrate another example of scheduling of a plurality of eNBs operating in the associated multipoint scheme in FIG. 3.
8 is a layout view of PeNB and SeNB according to an embodiment of the present invention.
9 is a diagram for explaining another example of a system operation scenario according to an associated multi-point method.
10 to 12 illustrate an example of scheduling of a plurality of eNBs operating in an associated multipoint scheme in FIG. 9.
13 is a layout view of a UE and an eNB.
14 is a flowchart illustrating a method of establishing a main cell link according to an embodiment of the present invention.
15 is a flowchart illustrating an operation of a UE according to an embodiment of the present invention.
16 is a flowchart illustrating an operation of a UE according to another example of the present invention.
17 is a flowchart illustrating the operation of a UE according to another example of the present invention.
18 is a flowchart illustrating a method of establishing a main cell link according to another example of the present invention.
19 is a block diagram illustrating a UE and an eNB operating in an associated multipoint scheme according to an embodiment of the present invention.

Hereinafter, some embodiments will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure rather unclear.

In addition, the present specification describes a wireless communication network, the operation performed in the wireless communication network is performed in the process of controlling the network and transmitting data in the system (for example, the base station) that manages the wireless communication network, or the corresponding wireless Work may be done at the terminal coupled to the network.

1 is a block diagram illustrating a wireless communication system.

Referring to FIG. 1, a wireless communication system is widely deployed to provide various communication services such as voice and packet data, and includes a user equipment (UE) 10 and an evolved NodeB (eNB) 20.

The UE 10 may be fixed or mobile and may be referred to by other terms such as a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device. The eNB 20 generally refers to a fixed station that communicates with the UE 10, and may be referred to in other terms such as a base transceiver system (BTS), an access point, and the like. One eNB 20 may provide a service for at least one cell. An interface for transmitting user traffic or control traffic may be used between the eNBs 20. In the following, downlink means communication from the eNB 20 to the UE 10, and uplink means communication from the UE 10 to the eNB 20. The downlink is also called a forward link, and the uplink is also called a reverse link. In downlink, the transmitter may be part of the eNB 20 and the receiver may be part of the UE 10. In uplink, the transmitter may be part of the UE 10 and the receiver may be part of the eNB 20.

The eNBs 20 may be connected to each other via an X2 interface. The eNB 20 is connected to an Evolved Packet Core (EPC), more specifically, a Mobility Management Entity (MME) / Serving Gateway (S-GW) 30 through an S1 interface. The S1 interface supports a many-to-many-relation between eNB 20 and MME / S-GW 30.

There is no restriction on the multiple access method applied to the wireless communication system. Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Single-Carrier FDMA (SC-FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), or other known modulation techniques. It can be based on the same multiple access techniques. These modulation techniques demodulate signals received from multiple users of a communication system to increase the capacity of the communication system.

The layers of the radio interface protocol between the UE and the network are based on the lower three layers of the Open System Interconnection (OSI) model, which are well known in communication systems. It may be divided into a second layer L2 and a third layer L3. Among them, the physical layer belonging to the first layer provides an information transfer service using a physical channel, and is a radio resource control (RRC) layer located in the third layer. Is responsible for controlling radio resources between the UE and the network. To this end, the RRC layer exchanges RRC messages between the UE and the network.

Scheduling information on uplink transmission includes information on resource allocation, hopping information, information on modulation and coding, information on HARQ process, new data indicator, power control information, and criteria for demodulation. It may include at least one of information on the resource of the signal, channel quality information (CQI) transmission request information.

One UE communicates with a plurality of cells according to a coordinated multiple point (CoMP) scheme. The associated multipoint scheme widely refers to a method in which different multiple cells cooperate to perform communication with one UE. A plurality of cells operating in an associated multipoint scheme are called coordinated cells, and a plurality of eNBs operating in an associated multipoint scheme are called coordinated eNBs. One eNB may provide a plurality of cells. Accordingly, the same eNB may provide associated cells, or different eNBs may provide associated cells. Meanwhile, UEs operating in an associated multipoint scheme are referred to as CoMP UEs, and UEs operating in a general communication scheme other than the associated multipoint scheme are referred to as non-CoMP UEs.

In the following description, a linked multi-point method is described in view of an eNB for convenience of description. That is, it is assumed that one eNB provides one cell, and associated cells are provided by different eNBs. However, when the associated multipoint scheme is described in terms of a cell, the associated cells may be interpreted to be provided by the same eNB.

Associated eNBs include a Primary eNB (PeNB) and a Secondary eNB (SeNB). PeNB has priority in scheduling among associated cells. That is, the PeNB is in charge of scheduling in an associated multipoint scheme, and the SeNBs perform scheduling so that no collision occurs in the scheduling result determined by the PeNB.

A cell provided by the PeNB is called a primary cell, and a radio link formed by the primary cell and the UE is called a primary cell link. The primary cell link has a priority of scheduling with respect to the secondary cell link. The cell provided by the SeNB is called a secondary cell, and the radio link formed by the secondary cell and the UE is called a secondary cell link. The SeNB may also be called a neighboring BS or another eNB. The PeNB may transmit downlink scheduling information of the SeNB as well as its downlink scheduling information.

In a typical cellular communication system, if each cell does not consider other cells and communicates between eNB and UE while maintaining frequency reuse '1' in the same time and frequency band, cell boundary The closer to the UE, the poorer the performance due to interference from other cells.

In order to overcome the performance deterioration caused by the interference, various techniques have been studied so far, and one of the techniques, the associated multi-point method, can effectively remove the effect of interference and improve the transmission rate of the entire system.

FIG. 2 is only an example of performing PeNB and SeNB-linked multipoint schemes to UEs capable of receiving signals from two or more base stations or cells, and shows the location and number of eNBs and cells performing the linked multipoint schemes. It is not limiting. The associated eNB may be appropriately determined in consideration of a distance between the UE and the neighbor eNB, a Signal to Interference and Noise Ratio (SINR), a Spectral Efficiency, and the like.

3 is a diagram illustrating an example of a system operation scenario according to an associated multi-point method. This is a case where PeNB and SeNB are dynamically configured according to the UE.

Referring to FIG. 3, the eNB1 310, the eNB2 320, and the eNB3 330 are determined as an associated eNB according to an associated multipoint scheme. UE1 341, UE2 342, and UE3 343 are connected to a cell provided by eNB1 310 through a primary access link. UE4 344, UE5 345, UE6 346, and UE7 347 are connected to the cell provided by eNB2 320 via a primary access link. UE8 348, UE9 349, UE10 350, UE11 351, and UE0 340 are connected to a cell provided by eNB3 330 through a primary access link.

Among them, UE0 340, UE1 341, and UE7 347 are terminals capable of receiving signals from two or more base stations, and operate in an associated multi-point manner to increase communication capacity. The remaining UEs operate in a general communication mode rather than an associated multipoint method.

UEs operating according to a general communication scheme have only one main cell link. For example, UE2 342 and UE3 343 are connected to eNB1 310 through main cell links P ₂ and P ₃ , respectively. UE4 344, UE5 345 and UE6 346 are connected to eNB2 320 with main cell links P ₄ and P ₅ , respectively. And P ₆ . The UE8 348, the UE9 349, the UE10 350, and the UE11 351 are connected to the eNB3 330 with main cell links P ₈ and P ₉ , respectively. And P ₁₀ and P ₁₁ .

According to the linked multi-point method, since two or more eNBs communicate with each other in a single UE, two or more cell links are formed. For example, UE0 340 is connected to eNB1 310 by a secondary cell link S ₀ , and is connected to eNB3 330 by a primary cell link P ₀ . UE1 341 is connected to eNB1 310 through a primary cell link P ₁ , and is connected to eNB2 320 with a secondary cell link S ₁ . The UE7 347 is connected to the eNB1 310 through the secondary cell link S ₇ , and is connected to the eNB3 330 through the main cell link P ₇ .

Although UE4 340, UE1 341, and UE7 347 operate according to the associated multipoint scheme, PeNB and SeNB are determined relatively for each UE. In FIG. 3, the PeNB for UE0 340 is eNB3 330, the PeNB for UE1 341 is eNB1 310, and the PeNB for UE7 347 is eNB2 320.

If the PeNBs are different for each UE, a plurality of PeNBs may allocate the same radio resource to each other, thereby causing a collision in scheduling. In addition, there is a concern that the scheduling complexity increases with the scheduling of the UE according to the general communication method.

4 and 5 are examples illustrating scheduling of a plurality of eNBs operating in the multi-point method associated with FIG. 3. 4 illustrates an initial scheduling result, and FIG. 5 illustrates a result of scheduling being performed again by eNBs sharing scheduling information according to an associated multipoint scheme.

4 and 5, the eNB1 310, the eNB2 320, and the eNB3 330 each have nine subbands (subband, a, b, c, d, e, f, g, h, and i). Is allocated to the UE linked with it, and one subband is allocated to each UE. The number written in the subband indicates the index of the UE.

eNB1 310 is a serving eNB for UE1 341, UE2 342, UE3 343, and eNB2 320 is UE4 344, UE5 345, UE6 346, UE7 A serving base station for 347, and eNB3 330 is a serving base station for UE0 340, UE8 348, UE9 349, UE10 350, UE11 351.

UE2 342, UE3 343, UE4 344, UE5 345, UE6 346, UE8 348, UE9 349, UE10 350, and UE11 351 are not affected by interference. Since it does not cause cell-to-cell interference, it is possible to operate in a general communication method at another base station using the same subband. That is, not all UEs are subjected to interference from neighboring base stations, and only UEs having a certain propagation gain of a link with the neighboring base station among the UEs are affected by intercell interference.

On the other hand, for UE0 340, UE1 341, and UE7 347, which are affected by the interference, all other UEs and subbands should be allocated exclusively in the PeNB and SeNB transmitting signals to the corresponding UEs. In case of interference, reception performance of terminals is degraded. For example, as shown in FIG. 4, since subband d is allocated to eNB3 330 by UE0 340, eNB1 310 allocates subband d to UE1 341, UE2 342, or UE3 343. I never do that. In addition, since UE1 341 is allocated subband c by eNB1 310, eNB2 320 allocates subband c to UE4 344, UE5 345, UE6 346, or UE7 347. I never do that. Similarly, UE7 347 is assigned subband a by eNB2 320, so eNB2 320 assigns subband a to UE4 344, UE5 345, UE6 346, or UE7 347. I never do that.

To increase reception strength for UEs that are in the impact zone of interference, UE0 340, UE1 341 and UE7 347 may operate in an associated multipoint manner. Therefore, the initial scheduling as shown in FIG. 4 may be changed as shown in FIG. 5. In FIG. 5, PeNB for UE1 341 is eNB1 310 and SeNB is eNB2 320. Since interference does not occur even if the same subband is allocated to the same UE, the eNB2 320 additionally allocates the subband c, which was unallocated at the time of initial scheduling, to the UE1 341. Rescheduling is called rescheduling because additional allocation is required in the linked multi-point method. By this same pattern, eNB1 310, which is the SeNB for UE7 347, further allocates subband a to UE7 347 that was unassigned at the time of initial scheduling. And eNB1 310, which is the SeNB for UE0 340, further allocates subband d, which was unallocated at the time of initial scheduling, to UE7 347. The additional allocation of the subbands here means that two or more eNBs use the same band in the process of transmitting a signal to one UE, but does not necessarily mean that the signals must be simultaneously transmitted.

As such, when the SeNB additionally allocates a subband to the UE by rescheduling, reception reliability of the UE may be improved. In FIG. 4 and FIG. 5, since only one subband is allocated to each UE, the traffic load is low. However, in an overload situation where two or more subbands are allocated for each UE, significant constraints may be placed on rescheduling.

6 and 7 illustrate another example of scheduling of a plurality of eNBs operating in the associated multipoint scheme in FIG. 3. FIG. 6 shows an initial scheduling result, and FIG. 7 shows a result of scheduling being performed again by eNBs sharing scheduling information according to an associated multipoint scheme.

6 and 7, eNB1 310, eNB2 320, and eNB3 330 each have nine subbands (subband, a, b, c, d, e, f, g, h, i). Is allocated to the UE linked with it, and two subbands are allocated to each UE.

To increase reception strength for UEs that are in the impact zone of interference, UE0 340, UE1 341 and UE7 347 may operate in an associated multipoint manner. First, in FIG. 6, eNB3 330, which is a PeNB for UE0 340, assigns subbands c and d to UE0 340. Since UE0 340 operates in an associated multi-point manner, eNB3 330 delivers scheduling information for UE0 340 to eNB1 310, which is an SeNB for UE0 340. Accordingly, eNB1 310 allocates subbands c and d to UE0 340 in the same manner as eNB3 330 as shown in FIG. 7. However, the subband c is a band already used by the UE1 341. Thus, a collision occurs in the scheduling. The same applies to the subbands b and c of the eNB2 320.

Since the PeNB for the UE operating in the associated multipoint scheme is relatively determined, and a plurality of neighboring eNBs all become PeNBs, it is ambiguous which eNB should be scheduled first. Therefore, scheduling conflict occurs. In order to prevent such scheduling collision, role sharing should be clearly performed between eNBs. It is necessary to clarify the operation procedure of the eNB and the UE in an environment in which an eNB operating as a PeNB among a plurality of eNBs supporting an associated multipoint scheme is predefined.

8 is a layout view of PeNB and SeNB according to an embodiment of the present invention.

Referring to FIG. 8, eNBs adjacent to each other may be designated as SeNBs, and eNBs not adjacent to each other may be designated as PeNBs. For example, PeNB1 811, PeNB2 812, and PeNB3 813 are not adjacent to each other. In contrast, SeNB1 822 is adjacent to SeNB2 821, SeNB3 823, and SeNB4 824. That is, if either eNB is designated as PeNB, all neighboring eNBs around the PeNB are designated as SeNB. As such, the deployment of SeNB has a shape in which one PeNB surrounds multiple SeNBs.

9 is a diagram for explaining another example of a system operation scenario according to an associated multi-point method. In FIG. 9, the arrangement of eNBs and UEs is the same as that of FIG. 3.

Referring to FIG. 9, eNB1 910, eNB2 920, and eNB3 930 are determined as an associated eNB according to an associated multipoint scheme. Cells provided by eNB1 910 include UE0 940, UE1 941, UE2 942, and UE3 943. Cells provided by the eNB2 920 include UE4 944, UE5 945, UE6 946, and UE7 947. Cells provided by eNB3 930 include UE8 948, UE9 949, UE10 950, and UE11 951.

Among them, the UE0 940, the UE1 941, and the UE7 947 can receive signals from two or more base stations or cells, and thus operate in an associated multipoint scheme. The remaining UEs operate by a general communication method rather than an associated multipoint method.

PeNBs of UE0 940, UE1 941 and UE7 947 are designated only eNB1 910. Accordingly, the link between eNB 910 and UE0 940 is the main cell link P ₀ , the link between eNB 910 and UE1 941 is the main cell link P ₁ , and the link between eNB 910 and UE7 947. Is formed as the main cell link P ₇ . The SeNBs providing the secondary cell links S ₀ , S ₁ , and S ₇ to UE0 940, UE1 941, and UE7 947 are eNB2 920 and eNB3 930, respectively.

Although UE7 947 is located in the cell provided by eNB2 920, PeNB for UE7 947 is characterized as eNB1 910. Since only eNB1 910 is PeNB, the other eNB2 920 and eNB3 930 prioritize scheduling of eNB1 910 and sub-schedule subband allocation for their terminals. In FIG. 9 in which PeNB is previously defined as eNB1 910 when comparing FIG. 9 and FIG. 3, CoMP UEs form only a main cell link with eNB1 910. On the other hand, in FIG. 3 in which PeNB is not defined in advance, CoMP UEs form a main cell link with each other eNB.

As described above, when a specific eNB is designated as a PeNB or a specific eNB as a PeNB among linked eNBs in a linked multi-point scheme, scheduling conflicts due to scheduling ambiguity may be resolved.

10 to 12 illustrate an example of scheduling of a plurality of eNBs operating in an associated multipoint scheme in FIG. 9. FIG. 10 shows an initial scheduling result, FIG. 11 shows a scheduling assignment request of the PeNB, and FIG. 12 shows a result of scheduling being performed again by reflecting the scheduling assignment request of the PeNB.

10 to 12, eNB1 910, eNB2 920, and eNB3 930 each link nine subbands a, b, c, d, e, f, g, h, and i with themselves. To one UE, but one or two subbands are allocated to each UE. To increase reception strength for UEs that are in the impact zone of interference, UE0 940, UE1 941 and UE7 947 can operate in an associated multipoint manner. And, PeNBs for UE0 940, UE1 941, and UE7 947 are all eNB1 910.

First, initial scheduling is as shown in FIG. That is, eNB1 910 allocates subbands c and d to UE0 940, assigns subband b to UE1 941, and assigns subband a to UE7 947. Then, when UE0 340 operates in an associated multi-point manner, eNB1 910 allocates subband b to UE1 941 and subband a to UE7 947 as shown in FIG. 11. Ask. ENB1 910 also requests eNB3 930 to assign subbands c and d to UE0 940. Such a request may be by signaling between eNBs or by signaling through a core network.

The eNB2 920 and the eNB3 930 that have received a request from the eNB1 910 perform rescheduling as shown in FIG. 12. As a result of the rescheduling, eNB2 920 assigns subband b initially allocated to UE5 945 to UE1 941 and assigns unused subband e to UE5 945. Meanwhile, eNB3 930 allocates unused subbands c and d to UE0 940.

If scheduling coordination is performed between PeNB and SeNB in this manner, scheduling conflicts between eNBs may be resolved in the associated multipoint scheme.

Hereinafter, a method in which a CoMP UE establishes a primary cell link with a PeNB in a PeNB-designated environment will be described in detail. First, it is assumed that the UE and the eNB are arranged as shown in FIG. 13.

Referring to FIG. 13, the UE 1330 is a non-CoMP UE and the serving eNB is an eNB2 1320. eNB1 1310 is currently only a neighbor base station, but is a potential PeNB. In one aspect, the potential PeNB may mean an eNB having a higher probability of being selected as a PeNB in a CoMP environment than a neighbor eNB. In another aspect, the potential PeNB may mean an eNB whose priority selected as PeNB in the CoMP environment is higher than the neighbor eNB. In another aspect, the potential PeNB may mean an eNB previously designated as PeNB in a CoMP environment.

If the channel situation deteriorates and the UE 1330 switches to a CoMP UE, there must be a clear decision about which eNB to select as the actual PeNB between eNB2 1320, the original serving eNB, and eNB1 1310, the potential PeNB. . Assume that links L ₂ is present between the UE (1330) and eNB2 (1320), and the link L ₁ is present between the UE (1330) and eNB1 (1310).

Since the eNB1 1310 is a potential PeNB, the UE 1330, the eNB1 1310, or the eNB2 1320 may enter the CoMP mode by setting the link L ₁ as the main cell link. This process involves a decision procedure for converting a potential PeNB into a real PeNB.

14 is a flowchart illustrating a method of establishing a main cell link according to an embodiment of the present invention.

Referring to FIG. 14, the UE 1330 measures a channel of link L ₁ with eNB1 1310 which is a potential PeNB, and transmits information about L ₁ to eNB2 1320 (S1400). The information about L ₁ may be information indicating inter-cell interference. Alternatively, the information about L ₁ may be a measurement report.

The eNB2 1320 receives the information about the L ₁ and notifies the eNB1 1310 of this (S1405).

The eNB1 1310 transmits link configuration information including link parameters necessary for establishing a main cell link to the eNB2 1320 (S1410), and the eNB2 1320 transmits the link configuration information to the UE 1330 (S1310). S1415). Alternatively, the eNB1 1310 may directly transmit link setting information to the UE 1330, and the subject transmitting the link setting information may be not only the eNB1 1310 but also the eNB2 1320.

Here, the link establishment information is information used by the UE 1330 to determine the actual PeNB. As one example, establishing a main cell link may be to perform a handover or to maintain a link. For example, if eNB1 1310 is determined to be an actual PeNB, link L ₁ is set to the primary cell link and link L ₂ is set to the secondary cell link, which is realized as a handover. In addition, when eNB2 1320 is determined to be a substantial PeNB, link L ₁ and link L ₂ are set to a secondary cell link and a primary cell link, respectively.

The UE 1330 determines whether to enter the linked multi-point mode based on the link establishment information (S1420). In one aspect, the link configuration information may include offset information to be considered in the handover between the eNB1 1310 and the eNB2 1320 to the UE 1330. In this case, the determination may be performed based on Equation 1 below.

Here, CQI _potential is a channel quality indicator (CQI) for a potential PeNB, and CQI _{serving The eNB} is a CQI for eNB2 1320, which is previously a serving eNB for UE 1330. CQI _potential CQI _serving self alone _eNB If greater, then eNB1 1310 is determined to be PeNB. However, CQI _potential <CQI _{serving for} most UEs located in a cell provided to eNB2 1320. _eNB will be established. Even under these conditions, in order for eNB1 1310 to become a PeNB, handover should be induced by comparing a CQI _{serving eNB} with a constant offset plus a CQI _potential .

In another aspect, the link establishment information may include threshold information to be considered in handover between the eNB1 1310 and the eNB2 1320. In this case, the determination may be performed based on Equation 2 below.

According to Equation 2, if the channel of the potential PeNB is larger than the threshold level, it means that L ₁ is set as the primary cell link. In other words, establishing the primary cell link and the secondary cell link is equivalent to setting the UE 1330, the eNB1 1310, and the eNB2 1320 to an associated multipoint mode.

In another aspect, the link configuration information may include a maximum allowable difference (MAD) to be considered in the handover between the eNB1 1310 and the eNB2 1320. In this case, the determination may be performed based on Equation 3 below.

Here, CQI _MAD is the maximum allowable difference value MAD. That is, when the relative difference between the channel of the potential PeNB and the channel of the serving eNB is smaller than a predetermined maximum allowable difference value, it means that L ₁ of the potential PeNB is set to the primary cell link.

In Equations 1 to 3, the CQI is used to represent the reception state of the channel, and the CQI may be due to the meaning of 3GPP specified as a channel quality indicator, and is a measurement value used for handover. It may be a reception power measurement value that is not an indexed value such as a reference signal received power (RSRP) value indicating another channel reception state. In addition, it may be a value such as RSRQ measured at the UE in consideration of the propagation state and interference of the channel. That is, the equation is described using a CQI for convenience, but the actual UE operation is not limited thereto, and various channel measurement values measured by the UE may be used. In addition, the offset and the CQI _{MAD that} are reflected in the process of determining the CoMP conversion by the UE through the same process as the above equation should also be selected differently depending on which measurement the UE determines the CoMP operation. For example, when the UE determines whether to CoMP by comparing the received power of the current PeNB and the reference signal transmitted by the tentative PeNB, the offset is not the offset of the CQI value, but the offset of the received power, and the CQI _MAD is an RSRP _MAD . Can be defined in other ways.

In another aspect, the link establishment information may include an indicator triggering to apply the offset information or threshold or the maximum allowable difference value that the UE 1330 already knows upon handover.

When the criterion for setting L ₁ as the primary cell link is satisfied, the UE 1330 performs handover to the potential PeNB to establish the primary cell link with the potential PeNB and the secondary cell link with the existing serving eNB. For example, in Equation 1, the offset value is 5, the second CQI value estimated from the reference signal RS of the eNB2 1320 is 8, and the first value estimated from the reference signal of the eNB1 1310. Assume that the CQI value is four. Since 4 + 5> 8, the UE 1330 performs a handover to the eNB1 1310. If Equation 1 is not satisfied, the UE 1330 does not enter the associated multi-point mode and maintains L ₂ as a serving cell. This is because the eNB1 1310 does not enter CoMP at all if the channel of the eNB1 1310 is not fixed in a fixed situation where only the eNB1 1310 becomes PeNB. Of course, if PeNB can be specified semi-persistent, when Equation 1 is not satisfied, eNB2 1320 is switched to PeNB, eNB1 1310 is switched to SeNB and L ₂ is It may be set as a main cell link. The measurement value used by the eNB for handover is not limited to the CQI, and all signals used by the UE for handover or inter-cell interference reporting can be used in the same manner as described above. That is, all signals used for inter-cell interference reporting or handover possibility reporting can be used to trigger eNB handover and CoMP driving.

15 is a flowchart illustrating an operation of a UE according to an embodiment of the present invention. This is a case where the UE establishes a main cell link according to Equation (1).

Referring to FIG. 15, the UE receives reference signals RS1 and RS2 transmitted from the current serving eNB and the potential PeNB, respectively (S1500). The UE measures channel C1 from RS1 and C2 from RS2 (S1505). The channel measurement value may simply be a measurement of reception power of a reference signal or data / control symbol, or may be a measurement of communication quality in consideration of reception power and noise, reception power, and interference and noise. The UE compares C1 'plus C2 with the offset value C1 (S1510). Step S1510 is equal to Equation 1 above. Here, the offset value may be received from a serving eNB or a potential PeNB, or may be known to the UE in advance.

If C1 '> C2 holds, the UE determines the potential PeNB as the actual PeNB and sets the link with the PeNB as the primary cell link (S1515). In this case, the existing serving eNB is switched to the SeNB. This is expressed by handover to potential PeNB. If the primary cell link is established, the SeNB and PeNB perform rescheduling (S1525). Rescheduling is as described above with reference to FIGS. 10 to 12. If C1 '> C2 does not hold, the UE does not enter the associated multipoint mode (S1520). Thus, only the link between the existing serving eNB and the UE is maintained.

16 is a flowchart illustrating an operation of a UE according to another example of the present invention. This is a case where the UE establishes a main cell link according to Equation 2.

Referring to FIG. 16, the UE receives reference signals RS1 and RS2 transmitted from the current serving eNB and the potential PeNB, respectively (S1600). The UE measures channel C1 from RS1 and C2 from RS2 (S1605). The UE compares C1 with a threshold value C _th (S1610). Step S1610 is the same as Equation 2 above. Here, the threshold may be received from a serving eNB or a potential PeNB, or may be known in advance by the UE.

If C1> C _th is established, the UE determines the potential PeNB as the actual PeNB and sets the link with the PeNB as the main cell link (S1615). This is expressed by handover to potential PeNB. If C1> C _th does not hold, the UE does not enter the associated multipoint mode (S1620). Thus, only the link between the existing serving eNB and the UE is maintained.

17 is a flowchart illustrating the operation of a UE according to another example of the present invention. This is a case where the UE establishes a main cell link according to Equation (3).

Referring to FIG. 17, the UE receives reference signals RS1 and RS2 transmitted from the current serving eNB and the potential PeNB, respectively (S1700). The UE measures channel C1 from RS1 and C2 from RS2 (S1705). The UE compares the difference between C1 and C2 with the maximum allowable difference value CQI _MAD (S1710). Step S1710 is the same as Equation 3 above. Here, the maximum allowable difference value may be received from a serving eNB or a potential PeNB, or may be known to the UE in advance.

If C1-C2 <CQI _MAD is established, the UE determines the potential PeNB as the actual PeNB and sets the link with the PeNB as the main cell link (S1715). This is expressed by handover to potential PeNB. If C1-C2 <CQI _MAD does not hold, the UE does not enter the associated multi-point mode (S1720). Thus, only the link between the existing serving eNB and the UE is maintained.

The subject that determines the establishment of the main cell link may be an eNB as well as a UE. Hereinafter, a method of determining and determining a main cell link configuration by an eNB will be described.

18 is a flowchart illustrating a method of establishing a main cell link according to another example of the present invention.

Referring to FIG. 18, the UE 1330 transmits information about L ₁ to the eNB2 1320 (S1800). The information about L ₁ may be information indicating inter-cell interference. Alternatively, the information about L ₁ may be a measurement report. Alternatively, the information about L ₁ may be a CQI.

The eNB2 1320 determines whether to set the link L ₁ between the eNB1 1310 and the UE 1330 as the main cell link (S1805). A criterion for determining whether to establish a main cell link may be, for example, the same as Equation 1 to Equation 3, but this is only an example, and the technical concept of the method for establishing the main cell link according to the present invention is the above. It is not limited to the equations (1) to (3).

When the main cell link is established, the eNB2 1320 reports a configuration request to the eNB1 1310 (S1810). Here, the configuration request may be requesting configuration regarding an associated multipoint scheme, or request to establish a link between the eNB1 1310 and the UE 1330 as a main cell link.

The eNB1 1310 that receives the configuration request transmits a configuration accept to the eNB2 1320 (S1815). The setup permission is to allow setup on the associated multi-point scheme or to set the link between the eNB1 1310 and the UE 1330 as the main cell link. The eNB2 1320 issues a handover command to the UE 1330 (S1820). If the link between the eNB1 1310 and the UE 1330 is set as the primary cell link by the handover, and the link between the eNB2 1320 and the UE 1330 is set as the secondary cell link, the eNB1 1310 becomes a PeNB. . Therefore, rescheduling is performed under the initiative of eNB1 1310 (S1825).

19 is a block diagram illustrating a UE and an eNB operating in an associated multipoint scheme according to an embodiment of the present invention.

Referring to FIG. 19, the UE 1900 includes a downlink receiver 1905, a channel measurer 1910, a link setup performer 1915, and an uplink transmitter 1920.

The downlink receiver 1905 receives a reference signal, link configuration information, or a handover command from the eNB 1950. In one aspect, the link establishment information may include offset information to consider when handing over to the UE 1990. In another aspect, the link establishment information may include threshold information to be considered during handover. In another aspect, the link establishment information may include a maximum allowable difference value to be considered in handover. In another aspect, the link establishment information may include an indicator that triggers application of offset information or threshold or maximum allowable difference value already known by the UE 1990 upon handover.

The channel measuring unit 1910 measures a channel from a reference signal transmitted from the eNB 1950 and generates information about a link between the eNB 1950 and the UE 1900.

The link establishment performing unit 1915 determines whether to set the link with the eNB 1950 as the main cell link based on the link establishment information (that is, whether to enter the CoMP mode), and enters the CoMP mode when the main cell link is established. do. The determining criterion may be, for example, the same as Equation 1 to Equation 3, but these are only exemplary embodiments. It is not limited to three. The uplink transmitter 1920 transmits information about a link obtained from the channel measurer 1910 to the eNB 1950.

The eNB 1950 includes a downlink transmitter 1955, an uplink receiver 1960, and a link setup controller 1965. The downlink transmitter 1955 transmits a reference signal, link configuration information, or a handover command to the UE 1900. The uplink receiver 1960 receives information about a link from the UE 1900.

The link establishment controller 1965 determines whether to set the link with the UE 1900 as the main cell link (that is, whether to enter the CoMP mode), and when the main cell link is set, the eNB 1950 controls to enter the CoMP mode. do. The determining criterion may be, for example, the same as Equation 1 to Equation 3, but these are only exemplary embodiments. It is not limited to three.

As the eNB to be switched to PeNB is pre-selected in the operation of the associated multipoint scheme, scheduling for the CoMP UE only occurs at the PeNB. The PeNB then delivers the result of scheduling or rescheduling for the CoMP UE to the SeNB. SeNB performs individual scheduling so as not to interfere depending on the result of the scheduling or rescheduling. In this method, scheduling is performed in consideration of CoMP, and thus, priorities between the eNBs are clear, and thus problems due to scheduling conflicts between other eNBs may be solved.

All of the above functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), or the like according to software or program code coded to perform the function. The design, development and implementation of the code will be apparent to those skilled in the art based on the description of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

Claims (12)

Measuring a channel on a first link between the first base station and the terminal;
Transmitting information regarding the first link to a second base station;
Receiving link configuration information from the first base station, the link configuration information used to set the first link as a primary cell link based on a coordinated multiple point scheme; And
And setting the first link as the primary cell link based on the link configuration information, and setting a second link between the second base station and the terminal as a secondary cell link.
The primary cell link has a priority of scheduling with respect to the secondary cell link, wherein the first base station, the second base station and the terminal operates in the associated multi-point method. The method of claim 1,
And wherein the first base station is previously designated as a primary base station providing the primary cell link to the second base station. The method of claim 1,
Wherein the link establishment information comprises an offset to be added to a value of a first channel quality indicator (CQI) for the first link. The method of claim 3, wherein
The first link is,
And if the sum of the value of the first channel quality indicator and the offset is greater than the value of the second channel quality indicator on the second link, the primary cell link. The method of claim 1,
The link establishment information includes information about a threshold value,
And if the value of the first channel quality indicator for the first link is greater than the threshold, the first link is set as the primary cell link. The method of claim 1,
The link establishment information includes information regarding a maximum allowable difference value,
If the difference between the value of the first channel quality indicator on the first link and the value of the second channel quality indicator on the second link is less than the maximum allowable difference value, the first link is set as the primary cell link. Characterized in that the method. The method of claim 1,
And the link establishment information includes an indicator for triggering to set the first link as the primary cell link. A channel measuring unit measuring a channel related to a first link between the first base station and the terminal;
A downlink receiving unit which receives from the first base station link setting information or a handover command used to set the first link as a primary cell link based on an associated multipoint scheme;
A link setting performing unit configured to set the first link as the main cell link based on the link setting information, and set a second link between a second base station and the terminal as a secondary cell link; And
An uplink transmitter for transmitting the information on the first link to the second base station,
The primary cell link has a priority of scheduling for the secondary cell link, and the first base station, the second base station and the terminal is characterized in that the operation in the associated multi-point method. Transmitting a reference signal used for measuring a channel related to a first link to a terminal;
Transmitting link setting information used to set the first link as a primary cell link to the terminal based on an associated multi-point scheme; And
And transmitting a handover command to the terminal for setting the first link as the primary cell link based on the link configuration information.
Wherein the primary cell link has a priority of scheduling with respect to the secondary cell link. The method of claim 9,
And performing scheduling for the terminal. 11. The method of claim 10,
And notifying a result of the scheduling to a base station configured as the terminal and the secondary cell link. The first link based on link setting information or link setting information used to set the first link as a primary cell link based on a reference signal or an associated multipoint scheme used for measuring a channel related to the first link. A downlink transmitter for transmitting a handover command to the terminal to set a primary cell link; And
And a link setting controller for controlling the main cell link to be set in the terminal, wherein the main cell link has a priority of scheduling for a secondary cell link.

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