WO2012108604A1 - 무선 접속 시스템에서 인접 셀 간 간섭을 회피하기 방법 및 장치 - Google Patents
무선 접속 시스템에서 인접 셀 간 간섭을 회피하기 방법 및 장치 Download PDFInfo
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- WO2012108604A1 WO2012108604A1 PCT/KR2011/007419 KR2011007419W WO2012108604A1 WO 2012108604 A1 WO2012108604 A1 WO 2012108604A1 KR 2011007419 W KR2011007419 W KR 2011007419W WO 2012108604 A1 WO2012108604 A1 WO 2012108604A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/50—Allocation or scheduling criteria for wireless resources
- H04W72/54—Allocation or scheduling criteria for wireless resources based on quality criteria
- H04W72/541—Allocation or scheduling criteria for wireless resources based on quality criteria using the level of interference
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- 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
- H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
- H04W16/04—Traffic adaptive resource partitioning
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/155—Ground-based stations
- H04B7/15528—Control of operation parameters of a relay station to exploit the physical medium
- H04B7/15542—Selecting at relay station its transmit and receive resources
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J11/00—Orthogonal multiplex systems, e.g. using WALSH codes
- H04J11/0023—Interference mitigation or co-ordination
- H04J11/005—Interference mitigation or co-ordination of intercell interference
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- 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
- H04W16/02—Resource partitioning among network components, e.g. reuse partitioning
- H04W16/10—Dynamic resource partitioning
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
- H04W84/04—Large scale networks; Deep hierarchical networks
- H04W84/042—Public Land Mobile systems, e.g. cellular systems
- H04W84/047—Public Land Mobile systems, e.g. cellular systems using dedicated repeater stations
Definitions
- the present disclosure relates to a wireless access system, and more particularly, to a method and an apparatus for avoiding inter-cell interference (ICI).
- ICI inter-cell interference
- 3GPP LTE (3rd Generation Partnership Project Long Term Evolution) -Advanced is a next-generation mobile communication system standard that expands cell coverage by installing relay nodes (RNs) in shaded areas and cell boundary areas. It supports multi-hop relay transmission technology that can be provided.
- RNs relay nodes
- Orthogonal Frequency-Division Multiple Access (OFDMA) technology is a modulation and demodulation scheme for overcoming multipath fading in a wireless channel, and uses multiple subcarriers to flexibly allocate time, frequency, and power resources to multiple users. There is an advantage to this.
- OFDMA Orthogonal Frequency-Division Multiple Access
- RA Resource Allocation
- OFDMA Resource Allocation
- a method of reallocating a resource in which collision occurs within relay node coverage to avoid inter-cell interference (ICI) while implementing a full dynamic RA method for each cell The purpose is to provide.
- the present specification relates to a method for a relay node (RN) to reallocate resources to avoid inter-cell interference (ICI) in a radio access system, wherein a plurality of base stations are the coverage of each base station.
- RN relay node
- ICI inter-cell interference
- the performing of the resource reassignment process may include exchanging a resource region where the collision occurs with a resource region allocated to terminals outside the relay node coverage.
- the exchanging with the resource region may include a signal-to-interference plus noise ratio (SINR) value of the resource region in which the collision occurs and a resource region allocated to terminals outside the relay node coverage. Comparing the SINR values respectively; And determining, as a result of the comparison, a resource region having a smallest difference in SINR value as a resource region to be exchanged.
- SINR signal-to-interference plus noise ratio
- the present specification is characterized by further comprising the step of transmitting downlink or uplink data to the terminal through the reallocated resource region.
- the plurality of base stations may perform a dynamic resource allocation process based on Full Frequency Reuse (FFR).
- FFR Full Frequency Reuse
- the plurality of base stations may include three base stations, and the relay node may be a shared relay node (SRN) shared by the three base stations.
- SRN shared relay node
- performing the resource reallocation process may include classifying all terminals within the relay node coverage into terminals corresponding to the respective base stations; And transmitting ratio information on the classified terminals to each base station.
- the control channel or the data is transmitted through a specific subframe, and the specific subframe includes a first time zone and a second time zone, and the first time zone. And the second time zone includes a downlink region and an uplink region, respectively.
- the first time zone is characterized in that the signal is transmitted and received between the base station and the terminal
- the second time zone is characterized in that the signal is transmitted and received between the base station and the terminal and / or relay node.
- the relay node is characterized in that using the plurality of base stations and X2 signaling.
- control channel is characterized in that the PDCCH or PUCCH.
- the step of reallocating the resource may include transmitting information indicating the resource area where the collision occurs to the plurality of base stations.
- the present specification is a relay node (RN) for reallocating resources to avoid inter-cell interference (ICI) in a radio access system, for transmitting and receiving radio signals with the outside Wireless communication unit; And a processor connected to the wireless communication unit, wherein the processor controls a plurality of base stations to overhear a control channel including downlink or uplink resource allocation information transmitted to terminals within coverage of each base station. Compares resource regions allocated to terminals within the relay node coverage through the control channel to determine whether there is a resource region in which a collision occurs; and if there is a resource region in which collision occurs, the collision occurs. Control to perform a resource reallocation process for the resource area, characterized in that the plurality of base stations share the relay node.
- RN relay node
- ICI inter-cell interference
- the processor may control to perform the resource reallocation process by exchanging a resource region where the collision occurs with a resource region allocated to terminals outside the relay node coverage.
- the processor compares a signal-to-interference plus noise ratio (SINR) value of the resource region where the collision occurs with a SINR value of a resource region allocated to terminals outside the relay node coverage, respectively.
- SINR signal-to-interference plus noise ratio
- the processor may control the wireless communication unit to transmit downlink or uplink data to the terminal through the reallocated resource region.
- the plurality of base stations may perform a dynamic resource allocation process based on Full Frequency Reuse (FFR).
- FFR Full Frequency Reuse
- the processor may classify all the terminals within the relay node coverage into terminals corresponding to the respective base stations, and control the wireless communication unit to transmit ratio information about the classified terminals to the respective base stations. do.
- the processor may control the wireless communication unit to transmit the information indicating the resource region where the collision occurs to the plurality of base stations.
- ICI Inter-Cell Interference
- FIG. 1 is a diagram illustrating a configuration of a relay backhaul link and a relay access link in a wireless communication system 100 to which an embodiment of the present specification can be applied.
- FIG. 2 is an internal block diagram of a base station 110 and a repeater 120 in a wireless communication system 100 to which an embodiment of the present disclosure can be applied.
- FIG. 3 is a diagram illustrating a multi-cell shared relay structure to which an embodiment of the present specification can be applied.
- FIGS. 4 (a) to (c) are diagrams illustrating a case where interference between neighbor cells occurs in a shared relay node based network structure.
- FIG. 5 illustrates a frame structure for applying a dynamic relay allocation method based on a shared relay node (SRN) to which an embodiment of the present specification can be applied.
- SRN shared relay node
- FIG. 6 (a) and (b) are diagrams illustrating signal transmission operations in respective time zones centered on the shared relay node SRN of FIG. 5.
- SRN shared relay node
- FIGS. 8 (a) to (c) are diagrams illustrating a case in which a collision occurs because the same resource block (RB) is allocated to terminals of a cell edge when each base station uses a dynamic resource allocation method.
- FIGS. 9 (a) to (c) are diagrams illustrating the division of RBs in a cell structure based on a shared relay node (SRN) according to the first embodiment of the present specification.
- FIG. 10 is a diagram illustrating an actual case of a collision resource block (RB) in a shared relay node (SRN) based cell structure according to the first embodiment of the present specification.
- FIG. 11 is a diagram illustrating a resource reallocation process for avoiding collision resource block (RB) in a shared relay node (SRN) based cell structure according to the first embodiment of the present specification.
- FIG. 12 is a diagram illustrating a resource reallocation method for ICI avoidance according to a third embodiment of the present specification.
- a terminal collectively refers to a mobile or fixed user terminal device such as a user equipment (UE), a mobile station (MS), and an advanced mobile station (AMS).
- the base station collectively refers to any node of the network side that communicates with the terminal such as a Node B, an eNode B, a Base Station, and an Access Point (AP).
- the repeater may be variously referred to as a relay node (RN), a relay station (RS), a relay, or the like.
- a user equipment and a repeater may receive information from a base station through downlink, and the terminal and repeater may also transmit information through uplink.
- the information transmitted or received by the terminal and the repeater includes data and various control information, and various physical channels exist according to the type and purpose of the information transmitted or received by the terminal and the repeater.
- FIG. 1 is a diagram illustrating a configuration of a relay backhaul link and a relay access link in a wireless communication system 100 to which an embodiment of the present specification can be applied.
- each of the uplink and downlink carrier frequencies while introducing a role of forwarding the link connection between the base station 110 and the terminal 130 to the repeater 120.
- Two kinds of links with different attributes are applied to the band.
- the connection link portion established between the link between the base station and the repeater is defined as a backhaul link.
- the transmission is performed in the frequency division duplex (FDD) or the time division duplex (TDD) method using the downlink resource, and is called backhaul downlink, and the transmission is performed in the FDD or TDD method using the uplink resource. It can be expressed as a backhaul uplink.
- FDD frequency division duplex
- TDD time division duplex
- the part of the connection link established between the relay and the terminals is defined and represented as a relay access link.
- a relay access link transmits using a downlink frequency band (in case of FDD) or a downlink subframe (in case of TDD), it is expressed as an access downlink and an uplink frequency band (in case of FDD).
- TDD uplink subframe
- the relay RN may receive information from the base station through the relay backhaul downlink, and may transmit information to the base station through the relay backhaul uplink.
- the repeater may transmit information to the terminal through the relay access downlink, and may receive information from the terminal through the relay access uplink.
- the repeater may perform an initial cell search operation such as synchronization with the base station. To this end, the repeater may receive a synchronization channel from the base station, synchronize with the base station, and obtain information such as a cell ID. Subsequently, the repeater may receive a physical broadcast channel from the base station to obtain broadcast information in a cell. Meanwhile, the repeater may check the channel state of the relay backhaul downlink by receiving a relay backhaul downlink reference signal in an initial cell search step. The repeater may receive more detailed system information by receiving a relay-physical downlink control channel (R-PDCCH) and / or a relay-physical downlink control channel (R-PDSCH).
- R-PDCCH relay-physical downlink control channel
- R-PDSCH relay-physical downlink control channel
- the repeater may perform a random access procedure (Random Access Procedure) to the base station.
- the repeater may transmit a preamble through a physical random access channel (PRACH) and the like, and receive a response message for the random access through the R-PDCCH and the corresponding R-PDSCH.
- PRACH physical random access channel
- contention resolution procedures such as transmission of additional physical random access channels and R-PDCCH / R-PDSCH reception may be performed.
- the repeater performing the above-described procedure is a general uplink / downlink signal transmission procedure, and then the R-PDCCH / R-PDSCH and the relay-physical uplink shared channel (R-PUSCH) / relay- A physical uplink control channel (R-PUCCH: Relay-Physical Uplink Control CHannel) transmission may be performed.
- R-PUSCH relay-physical uplink shared channel
- R-PUCCH Relay-Physical Uplink Control CHannel
- the control information transmitted from the repeater to the base station through the uplink or received from the repeater by the base station includes an ACK / NACK signal, a channel quality indicator (CQI), a precoding matrix index (PMI), and a rank.
- An indicator (Rank Indicator, RI) may be included.
- the repeater may transmit the above-described control information such as CQI, PMI, RI, etc. through the R-PUSCH / R-PUCCH.
- FIG. 2 is an internal block diagram of a base station 110 and a repeater 120 in a wireless communication system 100 to which an embodiment of the present disclosure can be applied.
- the wireless communication system 200 may include one or more base stations and / or one or more repeaters. .
- the base station 110 includes a transmit (Tx) data processor 111, a symbol modulator 112, a transmitter 113, a transmit / receive antenna 114, a processor 115, a memory 116, and a receiver ( 117, symbol demodulator 118, and receive data processor 119.
- Tx transmit
- symbol modulator 112 the base station 110 includes a transmit (Tx) data processor 111, a symbol modulator 112, a transmitter 113, a transmit / receive antenna 114, a processor 115, a memory 116, and a receiver ( 117, symbol demodulator 118, and receive data processor 119.
- the transmitter 113 and the receiver 117 may be represented by a radio (RF) communication unit.
- RF radio
- the repeater 120 may include a transmit (Tx) data processor 127, a symbol modulator 128, a transmitter 129, a transmit / receive antenna 121, a processor 125, a memory 126, a receiver 122, and a symbol. Demodulator 123, a receive data processor 124. Although antennas 114 and 121 are shown as one at base station 110 and repeater 120, respectively, base station 110 and repeater 120 are equipped with a plurality of antennas. Similarly, transmitter 129 and receiver 122 may be represented by a radio (RF) communication unit.
- RF radio
- the base station 110 and the repeater 120 according to the present invention supports a multiple input multiple output (MIMO) system.
- the base station 110 according to the present invention may support both a single user-MIMO (SU-MIMO) and a multi-user-MIMO (MU-MIMO) scheme.
- SU-MIMO single user-MIMO
- MU-MIMO multi-user-MIMO
- the transmit data processor 111 receives the traffic data, formats the received traffic data, codes it, interleaves and modulates (or symbol maps) the coded traffic data, and modulates the symbols ("data"). Symbols ").
- the symbol modulator 112 receives and processes these data symbols and pilot symbols to provide a stream of symbols.
- the symbol modulator 112 multiplexes data and pilot symbols and sends it to the transmitter 113.
- each transmission symbol may be a data symbol, a pilot symbol, or a null signal value.
- pilot symbols may be sent continuously.
- the pilot symbols may be frequency division multiplexing (FDM), orthogonal frequency division multiplexing (OFDM), time division multiplexing (TDM), or code division multiplexing (CDM) symbols.
- Transmitter 113 receives the stream of symbols and converts it into one or more analog signals, and further adjusts (eg, amplifies, filters, and frequency upconverts) these analog signals to provide a wireless channel. Generates a downlink signal suitable for transmission via the downlink signal, which is then transmitted to the repeater via antenna 114.
- the antenna 121 receives the downlink signal from the base station and provides the received signal to the receiver 122.
- Receiver 122 adjusts the received signal (eg, filtering, amplifying, and frequency downconverting), and digitizes the adjusted signal to obtain samples.
- the symbol demodulator 123 demodulates the received pilot symbols and provides them to the processor 125 for channel estimation.
- the symbol demodulator 123 also receives a frequency response estimate for the downlink from the processor 125 and performs data demodulation on the received data symbols to obtain a data symbol estimate (which is an estimate of the transmitted data symbols). Obtain and provide data symbol estimates to a receive (Rx) data processor 124. Receive data processor 124 demodulates (ie, symbol de-maps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data.
- Processing by the symbol demodulator 123 and the receiving data processor 124 is complementary to processing by the symbol modulator 112 and the transmitting data processor 111 at the base station 110, respectively.
- Repeater 120 is on the uplink, and transmit data processor 127 processes the traffic data to provide data symbols.
- the symbol modulator 128 can receive and multiplex data symbols, perform modulation, and provide a stream of symbols to the transmitter 129.
- the transmitter 129 receives and processes a stream of symbols to generate an uplink signal, which is transmitted to the base station 110 through the antenna 121.
- an uplink signal from the repeater 120 is received through the antenna 114, and the receiver 117 processes the received uplink signal to obtain samples.
- the symbol demodulator 118 then processes these samples to provide received pilot symbols and data symbol estimates for the uplink.
- Receive data processor 119 processes the data symbol estimates to recover traffic data sent from repeater 120.
- Processors 115 and 125 of repeater 120 and base station 110 respectively direct (eg, control, coordinate, manage, etc.) operation at repeater 120 and base station 110.
- Each processor 115, 125 may be coupled with memory units 116, 126 that store program codes and data.
- Memory units 116 and 126 are coupled to processor 115 to store operating systems, applications, and general files.
- the processors 115 and 125 may also be referred to as controllers, microcontrollers, microprocessors, microcomputers, or the like. Meanwhile, the processors 115 and 125 may be implemented by hardware or firmware, software, or a combination thereof. When implementing embodiments of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) configured to perform the present invention.
- ASICs application specific integrated circuits
- DSPs digital signal processors
- DSPDs digital signal processing devices
- PLDs programmable logic devices
- FPGAs Field Programmable Gate Arrays
- the firmware or software may be configured to include a module, a procedure, or a function for performing the functions or operations of the present invention, and to perform the present invention.
- the firmware or software configured to be may be included in the processors 115 and 125 or may be stored in the memories 116 and 126 to be driven by the processors 115 and 125.
- the layers of the air interface protocol between the repeater and the base station between the wireless communication system (network) are based on the first three layers (L1), the second layer ( L2), and the third layer L3.
- the physical layer belongs to the first layer and provides an information transmission service through a physical channel.
- a Radio Resource Control (RRC) layer belongs to the third layer and provides control radio resources between the UE and the network.
- the repeater, the base station can exchange RRC messages through the wireless communication network and the RRC layer.
- FIG. 3 is a diagram illustrating a multi-cell shared relay structure to which an embodiment of the present specification can be applied.
- ICI inter-cell interference
- the SRN is located at the center of three independent cells and performs data retransmission for improving throughput of a cell boundary region, which is a function of a basic relay.
- the SRN overhears the downlink signal and the uplink signal of the terminal 130 from each base station, and controls to avoid interference between terminals causing performance degradation in the cell boundary region. A detailed method thereof will be described later.
- the SRN is similar to the Type II RN functionally, but supports some additional functions than the Type II RN in terms of sharing control signals. That is, the SRN referred to herein has the same characteristics as 1 to 9 below.
- SRN does not have a separate cell ID and does not create another new cell.
- the SRN may transmit the PDSCH. (It may perform a function of relaying Rel-8 UEs.)
- Rel-8 UEs do not recognize the presence of an SRN.
- the SRN may transmit control (PDCCH, PUCCH, etc.) information to the eNBs through X2 signaling, but not to the UEs. (However, in the non-cooperative mode, the SRN can transmit the PDCCH signal without interference.)
- control PDCCH, PUCCH, etc.
- the SRN may restore control (PDCCH, PUCCH, etc.) information.
- SRN newly defines X2 signaling for sharing control information with eNB.
- SRN performs relay function only for UEs overhearing downlink and uplink signals of eNBs-UEs.
- the SRN has a function of identifying a UE in its area for coordination of intercell interference.
- SRN has a function of overhearing uplink SRS (Sounding Reference Signal) of UEs and discriminating them as UEs in the region of SRN based on an arbitrary threshold.
- SRS Sounding Reference Signal
- the SRN can overhear the Uplink SRS signal to measure the channel and change the MCS Level.
- the SRN overhears a plurality of eNBs-> UEs DL signals to share PDCCH and PDSCH information.
- the SRN overhears the UEs-> eNBs UL signal in its area to share PUCCH and PUSCH information.
- the SRN performs interference management between cells by using information shared by the methods 10 and 11 above.
- the interference management between the cell and the cell means all possible methods using the data obtained by the above 10 and 11. That is, based on the function of the SRN as described above, in this specification, the SRN, not eNBs, is the center of the cluster. It provides a method for sharing control information of eNBs and determining UEs where ICI occurs at cell boundary, and directly assigning resources for ICI avoidance by SRN.
- FIGS. 4 (a) to (c) are diagrams illustrating a case where interference between neighbor cells occurs in a shared relay node based network structure.
- 4A illustrates a case in which ICI occurs using the same resource in each of the direct links between the three base stations 110 and the terminal 130 (eNB1-UE1, eNB2-UE2, eNB3-UE3).
- 4B illustrates a case in which ICI occurs using the same resource in a direct link between two base stations and terminals (eNB1-UE1 and direct links of eNB2-UE2).
- 4C illustrates that when the SRN 120 retransmits a signal, when the eNB1-UE1 direct link and the SRN-UE2 access link use the same resource, the signal of the access link of the SRN becomes an interference source to the UE1 to generate ICI. The case is shown.
- FIG. 5 shows a frame structure for applying a SRN-based dynamic resource allocation (dynamic RA) method to which an embodiment of the present specification can be applied.
- dynamic RA dynamic resource allocation
- FIG. 5 shows a frame structure in each time zone centered on the SRN.
- the eNB transmits a data packet to UE M , and the SRN simultaneously overhears a packet transmitted by the eNB.
- the eNB transmits a data packet to the UE M , and the SRN relays only a UE R having a NACK in the 1st Time Zone.
- the SRN uses the same resource allocated to the eNB-UE M.
- the SRN-based dynamic RA is applied to the entire RB (Resource Block).
- the eNB transmits a common RS to the UE M to obtain channel quality indication (CQI) information of a corresponding band assigned to each resource region.
- CQI channel quality indication
- UE M calculates the CQI from the received common RS and delivers the CQI to the eNB through a time point when the corresponding uplink is opened.
- SRN transmits a dedicated RS (Reference Signal) to destination nodes in the eNB-SRN, SRN-UE R for the accurate decoding of the signal, the destination node of each link,
- the CQI may be calculated from the received dedicated RS, and the CQI may be delivered to the source nodes through the time point of opening each uplink.
- FIG. 6 (a) and (b) are diagrams illustrating signal transmission operations in respective time zones of the SRN center of FIG. 5.
- resources are allocated to the eNB-UE M in the 1st time zone so that each eNB transmits signals to UEs to which the eNB belongs.
- the SRN since the SRN is considered to be fixed and the propagation path is excellent, the SRN completely overhears signal transmission from the eNB to the UE.
- the SRN can transmit a signal to the SRN-UE through overhear in the 1st time zone without the link between the eNB-SRN, resource allocation for the eNB-SRN is not performed.
- the signal transmission from the eNB to the UE is still valid in the 2nd time zone, and the signal transmission from the SRN-> UE is valid only when the eNB-> UE is NACK generated.
- the SRN may operate in a cooperative mode and a non-cooperative mode.
- the same resource is used as eNB-> UE, and in the non-cooperative mode, the same resource allocated as the eNB-> UE is used. That is, the basic frame structure as shown in FIG. 5 may be considered.
- FIG. 7 is a diagram illustrating a dynamic RA method of each eNB in an SRN structure to which an embodiment of the present specification can be applied.
- Each eNB considers a structure for dynamically allocating all RBs based on Full Frequency Reuse (FFR), and allocates RBs to UEs through various scheduling techniques (PF, Max CINR, etc.).
- FFR Full Frequency Reuse
- the method in which the RBs do not overlap is referred to as non-overlap or non-cooperative.
- the SRN has no signal transmission to the eNB-UE and only considers the SRN-UE signal transmission.
- the resource overlap or resource cooperative method may transmit the same signal using the same RB to the eNB-UE and the SRN-UE, and may expect diversity gain.
- FIGS. 8 (a) to (c) are diagrams illustrating a case in which a collision occurs because the same RB is allocated to UEs at a cell edge when each eNB uses the Dynamic RA method.
- the region 800 corresponding to the hatched portion represents the region where resources collide with each other. That is, when multiple cells consider the FFR-based dynamic RA method, collisions occur when UEs at the cell edge use the same RB.
- the SRN provides a SRN-based resource reallocation method for ICI avoidance.
- the SRN is geographically located at the center of neighboring eNBs.
- This region where the SRN is located is the cell boundary area of eNBs, where the collision of RB occurs frequently and ICI is strongly influenced by neighboring eNBs. Therefore, the SRN has an advantageous geographical advantage to observe the occurrence of ICI in the center of the region where ICI of several eNBs is strongly operated.
- the SRN is capable of overhearing the signals of all eNBs-UEs.
- the SRN overhears the signals of eNBs-UEs, and can accurately detect the RBs in which collision occurs by using downlink and uplink control signals.
- the first embodiment provides a method in which an SRN overhears a control channel between an eNB and a UE so as to reallocate a resource region directly to a resource region where a collision occurs.
- B and B are angles Index and total number of UEs for
- UEs of the SRN may be classified as follows.
- the index of the RB can be expressed as follows.
- the SINR for each RB can be expressed as follows.
- the SRN uses the parameters to find an RB in which collision occurs in the region of the SRN, and reallocates resources for the collided RB. That is, the resource reallocation method for collision avoidance in this specification can be largely divided into 1) the process of finding the collision RB, and 2) the resource reallocation process for avoiding the collision RB.
- the SRN compares the S C of the SRN, that is, the RBs of the UEs within the coverage of the SRN, to find the RB where the collision occurs.
- RBs are divided into RBs 920 for UEs in the SRN and RBs 910 for UEs outside the SRN.
- the collision RBs 930 are shown.
- the process of finding the collision RB follows the following procedure.
- the UE finds all indexes using the same RB.
- the index k at which collision RB occurs for is specified as a variable of collision_k i (q) and stored as a vector string.
- the second step proposes a method of blocking ICI generation between eNBs in the cell boundary region using the collision RB index obtained in the first step.
- the main method is to exchange the RB where the collision has occurred and the RB outside the SRN region.
- the second step is to follow the steps below.
- each Here is how to remove collision RB for.
- the SRN updates the RB that is replaced by the RA.
- the RB set of S d is a region without ICI, unlike the region of S C.
- FIG. 10 is a diagram illustrating an actual case of a collision RB in an SRN based cell structure according to the first embodiment of the present specification.
- the first step of finding the collision RB may be represented as follows.
- the RB reallocation process through collision RB avoidance is examined through the second process.
- Collision_k 3 (1) 28
- Collision_k 3 (2) 32
- Collision_k 3 (3) 36
- FIG. 11 illustrates a resource reallocation process for collision RB avoidance in an SRN based cell structure according to the first embodiment of the present specification.
- the SIBs of the RBs in which collision has occurred and the RBs of UEs not in the region of the SRN are compared to each eNB, and the RBs having the smallest difference are selected to exchange RBs with each other.
- Black solid line 1100 represents an RB that can be replaced with a Collision RB.
- the second embodiment provides a method of reallocating collision resources by transmitting information for collision avoidance of a resource region allocated to a UE to a base station.
- the SRN may transmit information for preventing resource collision to the eNBs to prevent the eNBs from reallocating the resource to the UEs so that the resource does not collide.
- the information delivered by the SRN to the eNBs is as follows.
- the SRN can identify UEs that are within the coverage of the SRN. Therefore, after identifying the UEs in the SRN, the SRN transfers the IDs of the corresponding UEs to the eNBs.
- SRN overhears downlink and uplink signals transmitted and received between base stations and terminals and transmits IDs for UEs having NACKs (ie, resource collisions) to eNBs.
- NACKs ie, resource collisions
- each eNB that receives the two pieces of information from the SRN exchanges for the RB of the UEs in which the NACK has occurred, thereby preventing resource collision for the UEs.
- the RB to be exchanged is performed in the RB except for the RBs of the UEs in the area of the SRN.
- the third embodiment provides a method in which SRN and eNBs reallocate resources together when a resource collision occurs.
- the third embodiment provides a method in which the SRN partially processes the resource allocation avoidance information and transmits the processed information to each eNB to prevent the ICI, so that each eNB performs resource reallocation.
- a detailed method of the resource reallocation method according to the third embodiment may be performed as follows.
- SRN calculates proportionally the number of UEs in SRN for UEs served by each eNB.
- the SRN transfers the RBs area of the SRN UEs to each eNB by applying the ratio information calculated in (2) as the RB ratio.
- the third embodiment may not only be performed when a resource collision occurs, but also applies to a method in which each eNB allocates resources so that resource collision does not occur without HARQ timing, thereby causing a basic resource allocation to be collided. You can prevent it.
- each eNB may prevent resources from colliding in advance by allocating resources to the UE through the following methods.
- Each eNB receives a cell ID corresponding to each UE in the SRN from the SRN, and uses this to allocate resources to the UEs. Specifically,
- the SRN overhears its Uplink SRS signal and determines the UEs in the SRN. Thereafter, the SRN grasps the cell ID of each UE in the SRN, and then informs the corresponding cells that the UEs are UEs in the SRN. (It is assumed that resources are already statically divided for each cell.)
- the SRN classifies the UEs in the SRN by each cell ID, classifies the UEs in the SRN by the corresponding cell, identifies the number of UEs in the SRN for each cell, and then proportionally applies the entire resource region to apply the corresponding resource ratio. Inform each cell. Through this, each eNB performs resource allocation to the UEs (a method of dynamically classifying resources according to the number of UEs in the SRN).
- FIG. 12 is a diagram illustrating a resource reallocation method for ICI avoidance according to a third embodiment of the present specification.
- RBs for UEs in the SRN region are allocated as shown in FIG. 12 (1210, 1220, 1230).
- the SRN delivers RBs allocated for UEs to each eNB, each eNBs preferentially allocates SRN UEs in the corresponding shadow area, and dynamically allocates all other UEs to the remaining RBs. Assign.
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Abstract
Description
Claims (19)
- 무선 접속 시스템에서 인접 셀 간 간섭(Inter-Cell Interference:ICI)을 회피하기 위해 릴레이 노드(Relay Node:RN)가 자원을 재할당하기 위한 방법에 있어서,복수의 기지국이 각 기지국의 커버리지 내의 단말들로 전송하는 하향링크 또는 상향링크 자원 할당 정보를 포함하는 제어 채널을 엿듣는(overhear) 단계, 상기 복수의 기지국은 상기 릴레이 노드를 공유하며;상기 제어 채널을 통해 상기 릴레이 노드 커버리지 내의 단말들에게 할당되는 자원 영역을 비교하여 충돌이 발생하는 자원 영역이 있는지를 확인하는 단계;상기 확인 결과 충돌이 발생하는 자원 영역이 있는 경우, 상기 충돌이 발생하는 자원 영역에 대한 자원 재할당 과정을 수행하는 단계를 포함하여 이루어지는 것을 특징으로 하는 방법.
- 제 1항에 있어서, 상기 자원 재할당 과정을 수행하는 단계는,상기 충돌이 발생하는 자원 영역을 상기 릴레이 노드 커버리지 밖의 단말들에게 할당되는 자원 영역과 교환하는 단계를 포함하는 것을 특징으로 하는 방법.
- 제 2항에 있어서, 상기 자원 영역과 교환하는 단계는,상기 충돌이 발생하는 자원 영역의 신호 대 간섭 및 잡음비(Signal-to-Interference plus Noise Ration:SINR) 값과 상기 릴레이 노드 커버리지 밖의 단말들에게 할당되는 자원 영역의 SINR 값을 각각 비교하는 단계; 및상기 비교 결과, SINR 값의 차이가 가장 작은 자원 영역을 교환할 자원 영역으로 결정하는 단계를 포함하여 이루어지는 것을 특징으로 하는 방법.
- 제 1항에 있어서,상기 재할당된 자원 영역을 통해 단말로 하향링크 또는 상향링크 데이터를 전송하는 단계를 더 포함하는 것을 특징으로 하는 방법.
- 제 1항에 있어서,상기 복수의 기지국은 전체 주파수 재활용(Full Frequency Reuse:FFR) 기반의 동적 자원 할당(dynamic resource allocation) 과정을 수행하는 것을 특징으로 하는 방법.
- 제 1항에 있어서,상기 복수의 기지국은 3개의 기지국으로 구성되며,상기 릴레이 노드는,상기 3개의 기지국에 의해 공유되는 공유 릴레이 노드(Shared Relay Node:SRN)인 것을 특징으로 하는 방법.
- 제 1항에 있어서, 상기 자원 재할당 과정을 수행하는 단계는,상기 릴레이 노드 커버리지 내의 모든 단말들을 상기 각 기지국에 해당하는 단말들로 분류하는 단계; 및상기 분류된 단말들에 대한 비율 정보를 상기 각 기지국으로 전송하는 단계를 포함하는 것을 특징으로 하는 방법.
- 제 1항 또는 제 4항에 있어서,상기 제어 채널 또는 상기 데이터는 특정 서브 프레임을 통해 전송되되,상기 특정 서브 프레임은,제 1 시간 존(1st Time Zone) 및 제 2 시간 존(2nd Time Zone)으로 구성되며, 상기 제 1 시간 존 및 상기 제 2 시간 존은 각각 하향링크 영역 및 상향링크 영역으로 구성되는 것을 특징으로 하는 방법.
- 제 8항에 있어서,상기 제 1 시간 존은 기지국-단말 간의 신호가 송수신되며,상기 제 2 시간 존은 기지국-단말 간 및/또는 릴레이 노드-단말 간 신호가 송수신되는 것을 특징으로 하는 방법.
- 제 1항에 있어서,상기 릴레이 노드는 상기 복수의 기지국과 X2 시그널링을 이용하는 것을 특징으로 하는 방법.
- 제 1항에 있어서,상기 제어 채널은 PDCCH 또는 PUCCH인 것을 특징으로 하는 방법.
- 제 1항에 있어서, 상기 자원 재할당 과정을 수행하는 단계는,상기 충돌이 발생한 자원 영역을 나타내는 정보를 상기 복수의 기지국으로 전송하는 단계를 포함하여 이루어지는 것을 특징으로 하는 방법.
- 무선 접속 시스템에서 인접 셀 간 간섭(Inter-Cell Interference:ICI)을 회피하기 위해 자원을 재할당하기 위한 릴레이 노드(Relay Node:RN)에 있어서,외부와 무선신호를 송수신하기 위한 무선통신부; 및상기 무선통신부와 연결되는 프로세서를 포함하되, 상기 프로세서는,복수의 기지국이 각 기지국의 커버리지 내의 단말들로 전송하는 하향링크 또는 상향링크 자원 할당 정보를 포함하는 제어 채널을 엿듣(overhear)도록 제어하며, 상기 제어 채널을 통해 상기 릴레이 노드 커버리지 내의 단말들에게 할당되는 자원 영역을 비교하여 충돌이 발생하는 자원 영역이 있는지를 확인하고, 상기 확인 결과 충돌이 발생하는 자원 영역이 있는 경우, 상기 충돌이 발생하는 자원 영역에 대한 자원 재할당 과정을 수행하도록 제어하되,상기 복수의 기지국은 상기 릴레이 노드를 공유하는 것을 특징으로 하는 릴레이 노드.
- 제 13항에 있어서, 상기 프로세서는,상기 충돌이 발생하는 자원 영역을 상기 릴레이 노드 커버리지 밖의 단말들에게 할당되는 자원 영역과 교환하여 상기 자원 재할당 과정을 수행하도록 제어하는 것을 특징으로 하는 릴레이 노드.
- 제 14항에 있어서, 상기 프로세서는,상기 충돌이 발생하는 자원 영역의 신호 대 간섭 및 잡음비(Signal-to-Interference plus Noise Ration:SINR) 값과 상기 릴레이 노드 커버리지 밖의 단말들에게 할당되는 자원 영역의 SINR 값을 각각 비교하고, 상기 비교 결과, SINR 값의 차이가 가장 작은 자원 영역을 교환할 자원 영역으로 결정하는 것을 특징으로 하는 릴레이 노드.
- 제 13항에 있어서, 상기 프로세서는,상기 재할당된 자원 영역을 통해 단말로 하향링크 또는 상향링크 데이터를 전송하도록 상기 무선통신부를 제어하는 것을 특징으로 하는 릴레이 노드.
- 제 13항에 있어서,상기 복수의 기지국은 전체 주파수 재활용(Full Frequency Reuse:FFR) 기반의 동적 자원 할당(dynamic resource allocation) 과정을 수행하는 것을 특징으로 하는 릴레이 노드.
- 제 13항에 있어서, 상기 프로세서는,상기 릴레이 노드 커버리지 내의 모든 단말들을 상기 각 기지국에 해당하는 단말들로 분류하고, 상기 분류된 단말들에 대한 비율 정보를 상기 각 기지국으로 전송하도록 상기 무선통신부를 제어하는 것을 특징으로 하는 릴레이 노드.
- 제 13항에 있어서, 상기 프로세서는,상기 충돌이 발생한 자원 영역을 나타내는 정보를 상기 복수의 기지국으로 전송하도록 상기 무선통신부를 제어하는 것을 특징으로 하는 릴레이 노드.
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