KR20160076436A - Operation method of communication node in communication network including macro cell and small cell - Google Patents

Operation method of communication node in communication network including macro cell and small cell Download PDF

Info

Publication number
KR20160076436A
KR20160076436A KR1020150172480A KR20150172480A KR20160076436A KR 20160076436 A KR20160076436 A KR 20160076436A KR 1020150172480 A KR1020150172480 A KR 1020150172480A KR 20150172480 A KR20150172480 A KR 20150172480A KR 20160076436 A KR20160076436 A KR 20160076436A
Authority
KR
South Korea
Prior art keywords
base station
small base
secondary base
terminal
information
Prior art date
Application number
KR1020150172480A
Other languages
Korean (ko)
Inventor
이경석
윤미영
박애순
Original Assignee
한국전자통신연구원
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 한국전자통신연구원 filed Critical 한국전자통신연구원
Publication of KR20160076436A publication Critical patent/KR20160076436A/en

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/32—Hierarchical cell structures
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W48/00—Access restriction; Network selection; Access point selection
    • H04W48/08—Access restriction or access information delivery, e.g. discovery data delivery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W56/00—Synchronisation arrangements
    • H04W56/001—Synchronization between nodes
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access, e.g. scheduled or random access
    • H04W74/08—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access]
    • H04W74/0833—Non-scheduled or contention based access, e.g. random access, ALOHA, CSMA [Carrier Sense Multiple Access] using a random access procedure
    • H04W76/02—

Abstract

A method of operating a communication node in a communication network including a macro cell and a small cell is disclosed. A method of operating a first secondary base station includes receiving a discovery signal from a second secondary base station, determining whether a wireless link between the first secondary base station and the second secondary base station can be established based on the discovery signal, And establishing a radio link with the second secondary base station when the radio link state between the master base station and the first secondary base station does not satisfy a preset reference. Thus, the performance of the communication network can be improved.

Figure P1020150172480

Description

TECHNICAL FIELD [0001] The present invention relates to a method of operating a communication node in a communication network including a macro cell and a small cell.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to wireless communication technology, and more particularly, to a method of operating a communication node in an environment where macro cells and small cells exist.

A base station (hereinafter, referred to as a "macro base station") forming a macro cell may have a coverage within a radius of 20 km. User equipment in the coverage of the macro base station can access the macro base station and can communicate with the macro base station. The quality of service (QoS) and quality of experience (QoE) can be guaranteed because the channel state between the macro base station and the MS located near the macro base station is relatively good. On the other hand, the channel state between a macro base station and a terminal located in a shadow region (for example, an edge region of coverage) among the coverage of the macro base station may not be good, and QoS, QoE, etc. may be degraded. In addition, when traffic to be processed by the macro base station is very large, QoS, QoE, and the like may be degraded.

To solve this problem, a base station (hereinafter referred to as "small base station") that forms a small cell may be used. A small base station may have coverage within a radius of 200 meters. The small base station can be connected to the macro base station through a backhaul link and can operate under the control of the macro base station. The small base station may operate in the same frequency band as that of the macro base station, or may operate in a different frequency band than the frequency band in which the macro base station operates.

A small base station can be classified as a fixed small base station and a mobile small base station. The fixed small base station can be fixedly located at a specific place. On the other hand, the mobile small base station can move to another place as needed. When the mobile small base station moves, the mobile small base station may cause interference to neighboring cells (for example, macro cells, small cells, etc.), and may be a connection between the mobile small base station and the macro base station, Etc. can be a problem.

In order to solve the above problems, an object of the present invention is to provide a method of operating a communication node in an environment in which a macro cell and a small cell exist.

According to another aspect of the present invention, there is provided a method of operating a first secondary base station connected to a master base station, the method comprising: receiving a discovery signal from a second secondary base station; And determining whether a wireless link between the master secondary station and the second secondary base station can be established and setting the wireless link if the wireless link state between the master base station and the first secondary base station does not satisfy a preset reference And establishing a radio link with the second secondary base station.

Here, the discovery signal may include a type and a state of a radio link established in the second secondary base station, and information of a macro base station connected to the second secondary base station.

Here, the discovery signal may be received through the same frequency band as the frequency band of the radio link between the master base station and the first secondary base station.

Here, the second secondary base station may be connected to the master base station through a wireless link or a third secondary base station connected to the master base station.

According to another aspect of the present invention, there is provided a method of operating a terminal connected to a master base station, the method comprising: receiving synchronization signal related information from the master base station; Receiving a synchronization signal from the secondary base station based on the synchronization signal, establishing synchronization with the secondary base station based on the synchronization signal, receiving system information from the secondary base station, and accessing the secondary base station based on the system information .

Here, the synchronization signal related information may include an identifier of the secondary base station, resource information allocated to the synchronization signal, and transmission period information of the synchronization signal.

Here, the synchronization signal may be descrambled based on the identifier of the terminal.

Here, the system information may be descrambled based on the identifier of the UE.

Here, the resource to which the system information is allocated may be indicated by a resource allocated with the synchronization signal and a preset offset.

Here, the system information may include information on a terminal allowed to connect to the secondary base station.

According to another aspect of the present invention, there is provided a method of operating a terminal connected to a master base station, the method including receiving information of a secondary base station from the master base station, receiving a frequency band indicated by information of the secondary base station Transmitting the random access signal to the secondary base station, receiving the system information from the secondary base station, and accessing the secondary base station based on the system information.

Here, the information of the secondary base station may include an identifier of the secondary base station and frequency band information on which the secondary base station operates.

Here, the system information may be descrambled based on the identifier of the UE.

Here, the system information may include information on a terminal allowed to connect to the secondary base station.

According to the present invention, the performance of a communication network including a macro base station and a small base station can be improved. For example, quality of service (QoS), quality of experience (QoE), and the like can be improved in a communication network.

1 is a conceptual diagram showing an embodiment of a wireless communication network.
2 is a block diagram illustrating an embodiment of a communication node constituting a wireless communication network.
3 is a flowchart showing an embodiment of a connection method between a macro base station and a small base station.
4 is a flowchart showing an embodiment of a connection method between small base stations.
5 is a flowchart showing an embodiment of a connection method between a small base station and a mobile station.
6 is a flowchart showing another embodiment of a connection method between a small base station and a terminal.
7 is a flowchart illustrating an operation method of a small base station and a terminal according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

In the following, a wireless communication network to which embodiments according to the present invention are applied will be described. The wireless communication network to which the embodiments according to the present invention are applied is not limited to the following description, and the embodiments according to the present invention can be applied to various wireless communication networks.

1 is a conceptual diagram showing an embodiment of a wireless communication network.

Referring to FIG. 1, each of macro base stations 111 and 112 may form a macro cell. The macro base stations 111 and 112 may be referred to as a master base station. The coverage of each of the macro base stations 111 and 112 may be within a radius of 20 km. The coverage of the first macro base station 111 may overlap with the coverage of the second macro base station 112. Each of the small base stations 121, 122, and 123 may form a small cell. The small base stations 121, 122, and 123 may be referred to as secondary base stations. The coverage of each of the small base stations 121, 122, and 123 may be within a radius of 200 m. Each of the small base stations 121, 122 and 123 may be a fixed small base station or a mobile small base station. The fixed small base station can be fixedly located at a specific place. On the other hand, the mobile small base station can be moved to another place as needed and mounted on a vehicle or a train. In addition, the user can carry a mobile small base station.

 The coverage of the first small base station 121 may belong to the coverage of the first macro base station 111. The first small base station 121 may be connected to the first macro base station 111 via a wireless backhaul link or a wired backhaul link. For example, the first small base station 121 may be connected to the first macro base station 111 via a wireless backhaul link in case of a mobile small base station, and may be connected to the first macro base station 111 through a wired backhaul link in the case of a fixed small base station. . The frequency band in which the first small base station 121 operates may be the same as the frequency band of the first macro base station 111 or may be different from the frequency band of the first macro base station 111. [ The first small base station 121 can perform communication using a transmission power lower than the transmission power of the first macro base station 111. [

The coverage of the second small base station 122 may overlap with the coverage of the second macro base station 112. The second small base station 122 may be coupled to the second macro base station 112 via a wireless backhaul link or a wired backhaul link. For example, the second small base station 122 may be connected to the second macro base station 112 via a wireless backhaul link in the case of a mobile small base station, and may be connected to the second macro base station 112 . The frequency band in which the second small base station 122 operates may be the same as the frequency band of the second macro base station 112 or may be different from the frequency band of the second macro base station 112. [ The second small base station 122 can perform communication using a transmission power lower than the transmission power of the second macro base station 112. [

The coverage of the third small base station 123 may overlap with the coverage of the second small base station 122. [ The third small base station 123 may be connected to the adjacent small base station via a sidehaul link if it can not be connected to the first macro base station 111 or the second macro base station 112 via a wireless backhaul link or a wired backhaul link have. For example, the third small base station 123 may be connected to the second small base station 122 via a wireless side-hole link or a wire side-hole link. The third small base station 123 may be connected to the second small base station 122 via the wireless side hole link in the case of a mobile small base station and may be connected to the second small base station 122 via a wire side hole link in the case of a fixed small base station . Here, the third small base station 123 includes a side link (third small base station 123 - second small base station 122) + backhaul link (second small base station 122 - second macro base station 112) ) "To the second macro base station 112. The second macro base station 112 < RTI ID = 0.0 > The frequency band in which the third small base station 123 operates may be the same as the frequency band of the second macro base station 112 or may be different from the frequency band of the second macro base station 112. [ The third small base station 123 can perform communication using a transmission power lower than the transmission power of the second macro base station 112. [

The side hole links can be connected in a direct communication form between terminals. In the case of wireless communication, a packet including a MAC and a PHY layer header in a side-hall link can be transmitted / received through an uplink frequency. Further, an arbitrary indicator may indicate that the mobile small base station is a mobile base station. Any of the directives may be a cell identifier that is separately identified and may be displayed in the control information.

The first user equipment 131 may belong to the coverage of the first macro base station 111 and may be connected to the first macro base station 111 to perform communication. The second terminal 132 may belong to the coverage of the first macro base station 111 and the coverage of the first small base station 121. [ The second terminal 132 may be connected to at least one of the first macro base station 111 and the first small base station 121. The second terminal 132 can communicate with the first macro base station 111 when it is connected to the first macro base station 111 and can communicate with the second small base station 121 when it is connected to the first small base station 121 Lt; / RTI > The second terminal 132 can receive the control information through the first macro base station 111 when it is connected to the first macro base station 111 and the first small base station 121, Lt; / RTI > When communication with the first small base station 121 is performed, the second terminal 132 may use a reduced transmission power as compared to communication with the macro base station.

The third terminal 133 may belong to the coverage of the second macro base station 112 and may be connected to the second macro base station 112 to perform communication. The fourth terminal 134 may belong to the coverage of the second small base station 122 and may connect to the second small base station 122 to perform communication. When communication with the second small base station 122 is performed, the fourth terminal 134 may use a reduced transmission power compared to the communication with the macro base station. The fifth terminal 135 may belong to the coverage of the third small base station 123 and may connect to the third small base station 123 to perform communication. When communication with the third small base station 123 is performed, the fifth terminal 135 can use a reduced transmission power as compared with the communication with the macro base station.

A communication node (i.e., a base station, a terminal) constituting the wireless communication network described above may be a wireless communication system based on a communication protocol based on a code division multiple access (CDMA), a communication protocol based on a wideband CDMA (WCDMA) Based communication protocol, an orthogonal frequency division multiplexing (OFDM) based communication protocol, an orthogonal frequency division multiple access (OFDMA) communication protocol, a frequency division multiple access (FDMA) Based communication protocol and the like.

Among the communication nodes, a base station includes a Node B, an evolved Node B, a base transceiver station (BTS), a radio base station, a radio transceiver, an access point, Etc. < / RTI > Among the communication nodes, a terminal includes a terminal, an access terminal, a mobile terminal, a station, a subscriber station, a portable subscriber station, a mobile station ), A node, a device, and the like. The communication node may have the following structure.

2 is a block diagram illustrating an embodiment of a communication node constituting a wireless communication network.

Referring to FIG. 2, the communication node 200 may include at least one processor 210, a memory 220, and a transceiver 230 connected to the network to perform communication. The communication node 200 may further include an input interface device 240, an output interface device 250, a storage device 260, and the like. Each component included in the communication node 200 may be connected by a bus 270 and communicate with each other.

The processor 210 may execute a program command stored in at least one of the memory 220 and the storage device 260. The processor 210 may refer to a central processing unit (CPU), a graphics processing unit (GPU), or a dedicated processor on which methods in accordance with embodiments of the present invention are performed. Each of the memory 220 and the storage device 260 may be constituted of at least one of a volatile storage medium and a nonvolatile storage medium. For example, the memory 220 may comprise at least one of read-only memory (ROM) and random access memory (RAM).

Next, methods of operating the communication node in the wireless communication network will be described. Even if a method (e.g., transmission or reception of a signal) to be performed at the first communication node among the communication nodes is described, the corresponding second communication node is controlled by a method corresponding to the method performed at the first communication node For example, receiving or transmitting a signal). For example, when the operation of the terminal is described, the corresponding base station can perform an operation corresponding to the operation of the terminal. Conversely, when the operation of the base station is described, the corresponding terminal can perform an operation corresponding to the operation of the base station.

3 is a flowchart showing an embodiment of a connection method between a macro base station and a small base station.

Referring to FIG. 3, the macro base station may be the macro base station 111, 112 described with reference to FIG. 1, and may include the same or similar configuration as the communication node described with reference to FIG. The small base station may be the small base station 121, 122, 123 described with reference to FIG. 1 and may include the same or similar configuration as the communication node described with reference to FIG. The small base station can generate an access request signal for requesting connection to the macro base station (S300). The access request signal may refer to a signal requesting establishment and management of a backhaul link between the macro base station and the small base station. The access request signal includes an identifier (e.g., a cell ID) of a small base station, a frequency band (e.g., a primary frequency band, a secondary frequency band, etc.) .

The small base station can transmit the generated connection request signal (S310). The connection request signal may be transmitted periodically or aperiodically. The macro base station can receive the connection request signal, identify the small base station that transmitted the connection request signal based on the identifier included in the connection request signal, and determine whether the small base station can access the small base station based on the connection request signal have. For example, the macro base station can allow the connection of the small base station when the strength of the received connection request signal is equal to or greater than a preset threshold value, and when the strength of the received connection request signal is less than a preset threshold value, It may not be allowed. Alternatively, the macro base station may estimate the interference caused by the small base station based on the information included in the connection request signal, and may not allow the connection of the small base station when the estimated interference is equal to or greater than a preset threshold value. On the other hand, the macro base station can allow the connection of the small base station when the interference estimated based on the connection request signal is less than a preset threshold value.

A radio resource control (RRC) connection between the macro base station and the small base station can be established and a GTP (general packet radio services) tunneling protocol (GPRS) and a stream control transmission protocol (SCTP) A wireless backhaul link between the macro base station and the small base station may be established (S320).

Meanwhile, the small base station can receive the synchronization signal broadcasted by the macro base station, and can synchronize time and frequency based on the synchronization signal. When it is determined that the synchronization error between the macro base station and the small base station is small due to the received synchronization signal, the small base station can set the search period of the synchronization signal to be relatively long. In addition, when it is determined that the synchronization error between the macro base station and the small base station is very small due to the received synchronization signal, the small base station can stop searching for the synchronization signal. The small base station can periodically search for the distributed synchronization signal even in the presence of the synchronization signal of the macro base station. The distributed synchronization signal may be a synchronization signal broadcasted by the terminal, and may be broadcasted using the uplink frequency. When the terminal is located within the coverage of the base station, the time reference value of the distributed synchronization signal can be adapted to the synchronization signal of the base station, and thus the distributed synchronization signal can be broadcast. If the terminal is located outside the coverage of the base station, the distributed synchronization signal may be broadcast at will or may be broadcast in accordance with the neighboring distributed synchronization signal.

Data transmitted and received over a wireless backhaul link between a macro base station and a small base station may have a relatively high priority. For example, in a downlink transmission, a macro base station can transmit data to a small base station using a relatively high modulation and coding scheme (MCS) and transmission power. In addition, the macro base station can instruct the small base station to use relatively high MCS and transmission power in the uplink transmission through the wireless backhaul link. In the uplink transmission, the small base station can transmit data to the macro base station using a relatively high MCS and transmission power. Here, the small base station may perform multiplexing on data received from a plurality of terminals, and may transmit the multiplexed data to the macro base station through a wireless backhaul link.

Meanwhile, the small base station can be connected to the macro base station through the wireless backhaul link, and the state of the wireless backhaul link can be unstable according to the connection state between the macro base station and the small base station. For example, as the small base station moves, the distance between the macro base station and the small base station may be increased. In this case, the channel state of the wireless backhaul link between the macro base station and the small base station may deteriorate and communication may be difficult to maintain. When the state of the wireless backhaul link between the macro base station and the small base station is unstable, the small base station can not normally support the operation of the connected terminal. To compensate for this, the small base station may be connected to the neighboring small base station via a wireless link (e.g., a side-hole link). Here, the neighboring small base station may be connected to the macro base station through the backhaul link, or may be connected to the other small base station connected to the macro base station through the side hole link.

4 is a flowchart showing an embodiment of a connection method between small base stations.

Referring to FIG. 4, each of the first small base station and the second small base station may be the small base station 121, 122, 123 described with reference to FIG. 1 and may be the same or similar to the communication node described with reference to FIG. Configuration. The first small base station may be coupled to the macro base station or may be coupled to a neighboring small base station connected to the macro base station. The first small base station may generate a discovery signal for a direct connection between the small base stations. The discovery signal may include a type of radio link of the first small base station (e.g., a wireless backhaul link, a wireless side-hole link, etc.) and a state (e.g., data rate, error rate, latency, Etc.), information of the macro base station connected to the first small base station (e.g., cell ID, frequency band information on which the macro base station operates), and the like. The first small base station may periodically or aperiodically transmit the discovery signal (S400). The discovery signal may be broadcasted in a direct communication format between terminals, and may be configured to transmit fixed size data periodically.

Here, the resource to which the discovery signal is allocated may be a resource allocated with a synchronization signal transmitted from the first small base station and an offset from the resource, or a resource to which system information transmitted from the first small base station is allocated, Lt; / RTI > The offset may be signaled by the macro base station associated with the first small base station and the first small base station. The first small base station can transmit the discovery signal through the same frequency band as the frequency band of the backhaul link with the connected macro base station (or the same frequency band as the frequency band of the side-hole link with the connected neighboring small base station). The minimum transmit power and the maximum transmit power of the discovery signal may be preset and the first small base station may use the minimum transmit power at the initial transmission of the discovery signal and then increase the transmit power of the discovery signal at each subsequent transmission period . The first small base station can increase the transmission power of the discovery signal up to the maximum transmission power. If the first small base station fails to acquire the discovery signal of the other small base station through a discovery procedure (for example, a procedure for transmitting and receiving a discovery signal) or when a side-hole link with a new small base station is established or for a preset time, The transmission power can be reduced.

Meanwhile, the second small base station may be connected to the macro base station through the backhaul link or may be connected to the neighboring small base station through the side hole link. The macro base station connected to the second small base station may be the same as the macro base station connected to the first small base station or may be different from the macro base station connected to the first small base station. The second small base station can generate a discovery signal. The discovery signal may include a type of radio link (e.g., a wireless backhaul link, a wireless side-hole link, etc.) and status (e.g., data rate, error rate, latency, etc.) of a second small base station, Information on the macro base station (e.g., cell ID, frequency band information on which the macro base station operates, etc.), and the like. The second small base station may periodically or aperiodically transmit the discovery signal (S410).

Here, the resource to which the discovery signal is allocated is allocated to the resource to which the synchronization signal transmitted from the second small base station is allocated and the offset from the resource, or to the offset from the resource to which the system information transmitted from the second small base station is allocated ≪ / RTI > The offset may be signaled by the macro base station connected to the second small base station and the second small base station. The second small base station can transmit the discovery signal through the same frequency band as the frequency band of the backhaul link with the connected macro base station (or the same frequency band as the frequency band of the side-hole link with the connected neighboring small base station). The minimum transmit power and the maximum transmit power of the discovery signal may be set in advance and the second small base station may use the minimum transmit power at the initial transmission of the discovery signal and increase the transmit power of the discovery signal at each subsequent transmission period . The second small base station can increase the transmission power of the discovery signal up to the maximum transmission power. The second small base station can reduce the transmission power of the discovery signal when the side hall link with the new small base station is established through the discovery procedure or when the discovery signal of the other small base station can not be obtained for a preset time.

In order to receive the discovery signal from the other small base station, the first base station transmits the same frequency band as the frequency band of the backhaul link with the connected macro base station (or the same frequency band as the frequency band of the side hall link with the neighboring small base station) Can be searched. The first small base station may receive the discovery signal from the second small base station through the frequency band. The first small base station can determine whether a side-hole link between the first small base station and the second small base station can be established based on the received discovery signal (S420).

For example, if the strength of the received discovery signal is equal to or greater than a preset threshold value, the first small base station can determine that a side-hole link can be established with the second small base station. When the first small base station determines that the macro base station connected to the first small base station is the same as the macro base station connected to the second small base station based on the information included in the received discovery signal, It can be judged that this is possible. Also, the first small base station can establish a side-hole link with the second small base station when the channel condition between the first small base station and the second small base station satisfies a preset reference based on the information included in the received discovery signal It can be judged. The first small base station can store the information of the second small base station capable of setting the side-hole link (for example, information included in the discovery signal received from the second small base station, identifier of the second small base station, etc.).

The first small base station may periodically or non-periodically measure the backhaul link state (or the side-hole link state with the connected neighboring small base station) with the connected macro base station (S430). When the first small base station does not satisfy the preset reference (for example, the backhaul link (or the side-hole link) with the connected macro base station (or the side-hole link state with the neighboring small base station) When the data rate in the backhaul link (or the side-hole link) is equal to or greater than a predetermined threshold, the error rate in the backhaul link (or side-hole link) is equal to or greater than the preset threshold value, ) Side hole link (S440). For example, the first small base station may transmit a link establishment request signal to the second small base station determined to be capable of setting a side-hole link. The link setup request signal may include an identifier of the first small base station, frequency band information on which the first small base station operates, and the like.

The second small base station can receive the link establishment request signal from the first small base station and set up the side hall link between the first small base station and the second small base station at the request of the first small base station (S450). (First small base station - second small base station) + backhaul link (second small base station - macro base station) "when the side small link between the first small base station and the second small base station is established, Lt; RTI ID = 0.0 > a < / RTI > macro base station.

Next, a connection method between the small base station and the terminal will be described.

5 is a flowchart showing an embodiment of a connection method between a small base station and a terminal.

Referring to FIG. 5, the macro base station may be the macro base station 111, 112 described with reference to FIG. 1, and may include the same or similar configuration as the communication node described with reference to FIG. The small base station may be the small base station 121, 122, 123 described with reference to FIG. 1 and may include the same or similar configuration as the communication node described with reference to FIG. The terminal may be the terminal 131, 132, 133, 134, 135 described with reference to FIG. 1, and may include the same or similar configuration as the communication node described with reference to FIG. The small base station can be connected to the macro base station through the backhaul link. The terminal may be located within the coverage of the macro base station and the coverage of the small base station.

The macro base station can generate information related to a synchronization signal (e.g., a primary synchronization signal (PSS), a secondary synchronization signal (SSS), etc.) to be transmitted by the small base station. The synchronous signal related information includes an identifier (e.g., a cell ID) of a small base station, resource information (e.g., SFN (system frame number) 0) to which a synchronous signal is allocated, , 10 ms, 100 ms, etc.), and the like. Here, the SFN can be set based on the macro base station. In addition, the synchronization signal related information may further include resource information to which system information of a small base station (for example, a physical broadcast channel (PBCH) including system information) is allocated. The resource to which the system information is allocated can be represented by a resource to which a synchronization signal is allocated and an offset from the resource. Here, the offset may be mapped to the identifier of the small base station, or may be mapped to the identifier of the macro base station and the identifier of the small base station. For example, if the identifier of the small base station is 10, the offset may be set to 10. The macro base station may transmit the synchronization signal related information to the small base station through the backhaul link and may transmit the synchronization signal related information in a broadcasting manner (S500).

The small base station can receive the synchronization signal related information from the macro base station and can confirm the resource to which the synchronization signal is allocated and the transmission period of the synchronization signal based on the received synchronization signal related information. The small base station may transmit the synchronization signal at a determined transmission period (for example, 10 ms, 100 ms, etc.) through the identified resource (e.g., SFN 0) (S510). Herein, when the small base station knows the information of the terminals allowed to access (for example, the identifier of the terminal, the group identifier to which the terminal belongs, etc.), the identifier of the terminal allowed to access (or the terminal Group identifiers) can be used to scramble the sync signal and transmit the scrambled sync signal. The allowed terminal information may be held by the terminal or may be set by the base station. If the terminal supports hardware and standards that can be connected to a mobile small base station, the terminal may be marked as allowed.

Also, the small base station can transmit the synchronization signal using the minimum transmission power. If it is determined that the transmission of the synchronization signal causes interference to the neighboring base station (for example, macro base station, small base station, etc.) A synchronous signal can be transmitted using a low transmission power. In this case, the small base station can set the transmission period of the synchronization signal longer. The UE can receive the synchronization signal related information from the macro base station and can confirm the resource to which the synchronization signal is allocated and the transmission period of the synchronization signal based on the received synchronization signal related information. The UE can receive the synchronization signal from the small base station based on the resource to which the synchronization signal is allocated, the transmission period of the synchronization signal, and the like.

For example, the UE can perform descrambling on the synchronization signal using its own identifier (or an identifier of the group to which the UE belongs), and can acquire the synchronization signal when the descrambling is successfully completed have. On the other hand, if the identifier used for scrambling the synchronization signal differs from its identifier (or the identifier of the group to which it belongs), the terminal can not perform descrambling on the synchronization signal, have. The terminal can acquire time and frequency synchronization based on the acquired synchronization signal (S520).

The small base station can generate the system information. The system information may include an identifier (e.g., cell ID, etc.) of a small base station, a transmission power strength, an SFN, and the like. The small base station can transmit the system information through the resource indicated by the offset included in the synchronization signal related information (S530). Herein, when the small base station knows the information (e.g., the identifier of the terminal, the group identifier to which the terminal belongs) of the terminals allowed to access, the identifier of the terminal allowed to access (or the group identifier to which the terminal belongs) The system information can be scrambled and the scrambled system information can be transmitted.

In addition, system information can be transmitted using the minimum transmission power of the small base station. If it is determined that transmission of the system information causes interference to a neighboring base station (e.g., macro base station, small base station, etc.) System information can be transmitted using a low transmission power. In this case, the small base station can set the transmission period of the system information to be longer. Meanwhile, the system information may further include ACB (access class barring) information. The ACB information may include an identifier (or an identifier of a group) of a terminal to which a connection is permitted, a class to which a terminal (or a group) to which a connection is permitted, and the like. Classes can be classified according to the priority of the connection.

The UE can search for the PBCH in the resource indicated by the offset included in the synchronization signal related information. For example, the terminal can search for the PBCH in the resource indicated by the identifier of the small base station or the resource indicated by the identifier of the macro base station and the identifier of the small base station. The UE can acquire the system information of the small base station through the detected PBCH (S540). For example, the UE can perform descrambling on the system information using its own identifier (or an identifier of the group to which the UE belongs), and obtain system information when the descrambling is successfully completed. On the other hand, if the identifier used for scrambling the system information is different from the identifier used for scrambling the system information (or the identifier of the group to which the user belongs), the terminal can not perform descrambling on the system information, have. The terminal can access the small base station based on the system information (S550). On the other hand, when the system information includes ACB information, the terminal can access the small base station if the terminal is allowed to access by the ACB information. On the other hand, the terminal may not access the small base station unless it corresponds to a terminal allowed to be connected by the ACB information. The terminal can receive the system information, and if it is confirmed that the mobile station is a mobile small base station based on the received system information, it can not access the corresponding cell. The indicator indicating the mobile base station may be classified by the cell identifier or included in the system information.

6 is a flowchart showing another embodiment of a connection method between a small base station and a terminal.

Referring to FIG. 6, the macro base station may be the macro base station 111, 112 described with reference to FIG. 1, and may include the same or similar configuration as the communication node described with reference to FIG. The small base station may be the small base station 121, 122, 123 described with reference to FIG. 1 and may include the same or similar configuration as the communication node described with reference to FIG. The terminal may be the terminal 131, 132, 133, 134, 135 described with reference to FIG. 1, and may include the same or similar configuration as the communication node described with reference to FIG. The small base station can be connected to the macro base station via the backhaul link and can be synchronized to the macro base station. The terminal may be located within the coverage of the macro base station and the coverage of the small base station, and may be synchronized to the macro base station.

The macro base station can transmit the information of the small base station in a broadcasting scheme (S600). The information of the small base station may include an identifier (e.g., a cell ID) of a small base station, a frequency band (e.g., primary frequency band, secondary frequency band) The terminal can receive the information of the small base station from the macro base station. When the UE desires to access the small base station indicated by the information of the small base station, the terminal may transmit a random access signal to the small base station through the frequency band indicated by the information of the small base station (S610). The random access signal may be transmitted via a physical random access channel (PRACH). The resource to which the PRACH is allocated can be indicated by the resource to which the synchronization signal of the macro base station is allocated and the offset from the resource. The offset can be pre-signaled from the macro base station to the terminal and the small base station.

The small base station can receive the random access signal from the terminal and can transmit the system information to the terminal through the PBCH (S620). Here, the small base station can scramble the system information using the identifier of the terminal that transmitted the random access signal (or the group identifier to which the terminal belongs), and transmit the scrambled system information. In addition, the small base station can transmit system information using the minimum transmission power. If it is determined that transmission of the system information causes interference to a neighboring base station (e.g., macro base station, small base station, etc.) System information can be transmitted using a low transmission power. In this case, the small base station can set the transmission period of the system information to be longer. The small base station can transmit system information to the mobile station a predetermined number of times. On the other hand, the system information may further include ACB information. The ACB information may include an identifier (or an identifier of a group) of a terminal to which connection is permitted, a class to which a terminal (or a group) to which a connection is permitted, and the like. Classes can be classified according to the priority of the connection.

The terminal can acquire the system information from the small base station (S630). For example, the UE can perform descrambling on the system information using its own identifier (or an identifier of the group to which the UE belongs), and obtain system information when the descrambling is successfully completed. On the other hand, if the identifier used for scrambling the system information is different from the identifier used for scrambling the system information (or the identifier of the group to which the user belongs), the terminal can not perform descrambling on the system information, have. The terminal can access the small base station based on the system information (S640). On the other hand, if the system information includes ACB information, the terminal can access the small base station if it corresponds to a terminal that is allowed to access by the ACB information. On the other hand, the terminal may not access the small base station unless it corresponds to a terminal that is allowed to access by the ACB information.

7 is a flowchart illustrating an operation method of a small base station and a terminal according to an embodiment of the present invention.

Referring to FIG. 7, the small base station may be the small base station 121, 122, 123 described with reference to FIG. 1, and may include the same or similar configuration as the communication node described with reference to FIG. The terminal may be the terminal 131, 132, 133, 134, 135 described with reference to FIG. 1, and may include the same or similar configuration as the communication node described with reference to FIG. The small base station can be connected to the macro base station via the backhaul link and can be synchronized to the macro base station. A terminal can be connected to a small base station, and can be synchronized to a small base station.

The small base station can set at least one manager terminal among the connected terminals (S700). The small base station can always manage the manager terminal in the RRC connection state. The small base station can transmit information indicating that the terminal is set as the manager terminal to the terminal. Through this, the signaling overhead for RRC connection can be reduced. The MS connected to the small base station can measure the channel state with the small base station based on the downlink signal received from the small base station (S710), and can transmit the measured channel state information to the small base station (S720). Here, all terminals connected to the small base station can transmit channel state information to the small base station, or only the manager terminal can transmit channel state information to the small base station.

The small base station can receive channel state information from the terminal. The small base station can confirm the channel state between itself and the manager terminal based on the channel state information (S730). The small base station can adjust the transmission power based on the channel state between itself and the manager terminal (S740). For example, when the channel state between the small base station and the manager terminal satisfies a predetermined criterion (for example, when the manager terminal is located in the area close to the small base station and the channel state is good) The strength can be reduced, and the downlink signal can be transmitted to the terminal using the reduced transmission power. Accordingly, the interference caused by the transmission of the downlink signal can be reduced.

On the other hand, if the channel state between the small base station and the manager terminal does not satisfy the preset criteria (for example, the channel state between the small base station and the manager terminal is poor), the small base station can increase the transmission power , And may transmit the downlink signal to the terminal using the increased transmission power. In addition, when the channel state between the small base station and the manager terminal is not very good (for example, the manager terminal is located outside the coverage of the small base station), the small base station can cancel the setting of the manager terminal, Handover can be performed.

Meanwhile, the small base station can allocate resources to terminals in a fixed manner to minimize communication delay with the terminal. For example, a small base station may set the data channel to a fixed location or a fixed pattern. In addition, the small base station can support semi-persistent scheduling (SPS). When the data channel is fixedly set, the UE may not transmit data when there is no data to be transmitted to the small base station. Since the small base station has a smaller coverage than the macro base station, the difference between the downlink and uplink synchronization may not be large. Therefore, the uplink synchronization procedure (e.g., TA (timing advance)) may be omitted in the transmission between the small base station and the terminal.

The small base station may transmit a physical downlink control channel (PDCCH) to the mobile station, and transmission of the PDCCH may cause interference to neighboring base stations. Therefore, the small base station can minimize the transmission of the PDCCH. Alternatively, the small base station may transmit an enhanced-PDCCH (EPDCCH), and the EPDCCH may be allocated to a resource assigned to each mobile station. In this case, the UE can receive the EPDCCH through the resource allocated to the UE. For example, the small base station can transmit resource information to which the EPDCCH (or PDCCH) is allocated to the connected terminal, and the terminal can transmit the EPDCCH (or PDCCH) through the resources indicated by the resource information received from the small base station .

The methods according to the present invention can be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer readable medium may be those specially designed and constructed for the present invention or may be available to those skilled in the computer software.

Examples of computer readable media include hardware devices that are specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims (14)

A method of operating a first secondary base station connected to a master base station,
Receiving a discovery signal from a second secondary base station;
Determining whether a radio link between the first secondary base station and the second secondary base station can be established based on the discovery signal; And
And establishing a radio link with the second secondary base station if the radio link can be established and the radio link state between the master base station and the first secondary base station does not satisfy a predetermined criterion. A method of operating a secondary base station. The method according to claim 1,
Wherein the discovery signal includes a type and a state of a radio link established in the second secondary base station, and information of a macro base station connected to the second secondary base station. The method according to claim 1,
Wherein the discovery signal is received on the same frequency band as the frequency band of the radio link between the master base station and the first secondary base station. The method according to claim 1,
Wherein the second secondary base station is connected to the master base station via a wireless link or to a third secondary base station connected to the master base station. A method of operating a terminal connected to a master base station,
Receiving synchronization signal related information from the master base station;
Receiving a synchronization signal from a secondary base station through a resource indicated by the synchronization signal related information;
Setting synchronization with the secondary base station based on the synchronization signal;
Receiving system information from the secondary base station; And
And accessing the secondary base station based on the system information. The method of claim 5,
Wherein the synchronization signal related information includes an identifier of the secondary base station, resource information allocated to the synchronization signal, and transmission period information of the synchronization signal. The method of claim 5,
Wherein the synchronization signal is descrambled based on an identifier of the terminal. The method of claim 5,
Wherein the system information is descrambled based on an identifier of the terminal. The method of claim 5,
Wherein the resource to which the system information is allocated is indicated by a resource allocated with the synchronization signal and a preset offset. The method of claim 5,
Wherein the system information includes information of a terminal allowed to connect to the secondary base station. A method of operating a terminal connected to a master base station,
Receiving information of a secondary base station from the master base station;
Transmitting a random access signal to the secondary base station through a frequency band indicated by the information of the secondary base station;
Receiving system information from the secondary base station; And
And accessing the secondary base station based on the system information. The method of claim 11,
Wherein the information of the secondary base station includes an identifier of the secondary base station and frequency band information on which the secondary base station operates. The method of claim 11,
Wherein the system information is descrambled based on an identifier of the terminal. The method of claim 11,
Wherein the system information includes information of a terminal allowed to connect to the secondary base station.
KR1020150172480A 2014-12-22 2015-12-04 Operation method of communication node in communication network including macro cell and small cell KR20160076436A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020140185774 2014-12-22
KR20140185774 2014-12-22

Publications (1)

Publication Number Publication Date
KR20160076436A true KR20160076436A (en) 2016-06-30

Family

ID=56352865

Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020150172480A KR20160076436A (en) 2014-12-22 2015-12-04 Operation method of communication node in communication network including macro cell and small cell

Country Status (1)

Country Link
KR (1) KR20160076436A (en)

Similar Documents

Publication Publication Date Title
JP6480005B2 (en) User device and notification method
EP3280183B1 (en) Path selection method and device
US9432914B2 (en) Device-to-device communication
CN109644521B (en) Method, apparatus and computer readable medium for measurement reporting
KR101689490B1 (en) Method and apparatus for cell handover and reconfiguration
US20190075546A1 (en) User apparatus, base station, signal transmission method, and resource allocation method
US10645591B2 (en) Wireless communication system, communication terminal, base station and method for cell control
CN114073163B (en) Method and apparatus for random access procedure
US9363746B2 (en) Method and apparatus for selecting wireless local area network to be accessed by a user equipment within a cell in a mobile communication system
US20120026958A1 (en) System and method for multicarrier uplink control
JP6434166B2 (en) Management of inter-device synchronization signal (D2DSS) resources
KR20130035964A (en) Method for device-to-device communication based on cellular telecommunication system
EP2892258A1 (en) Mobile communication system, base station, user terminal, and processor
KR20120126032A (en) Method and appratus of cell selection in mobile communication system
US20140321355A1 (en) Relay using device-to-device communication in the infrastructure-based communication system
CN103098520A (en) Method and apparatus for transmitting available radio access possibilities in a communications area
EP3169123B1 (en) Base station, user equipment and associated methods
CN108029027B (en) Measuring method and device
WO2017130743A1 (en) Wireless terminal, communication apparatus, and base station
JP2015522231A (en) Spectrum allocation method and apparatus
KR20140080298A (en) Method, Terminal, and Control Apparatus for Device to Device Communication
JP6575525B2 (en) Apparatus, method, program, and storage medium
CN106664683B (en) Data transmission method and device
WO2019111317A1 (en) Base station device, radio communication system, and terminal device
KR20160076436A (en) Operation method of communication node in communication network including macro cell and small cell