JP2013132084A - Downlink transmission system and method for borrowing spectrum resources and channel resources from adjacent cells - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a downlink transmission system and a method for borrowing spectrum resources and channel resources from adjacent cells.SOLUTION: In the downlink transmission system, a wireless node of a cell having the terminal uses part or all of resource blocks in its transmitting channel and transmitting frequency band, and the wireless node of the adjacent cells of the cell having the terminal uses part or all of the resource blocks in their respective transmitting channels and transmitting frequency bands, to transmit service data to the terminal together in a single stream mode. With the present invention, a problem of the spectrum borrowing being restricted by a plurality of cells that exists in the relevant technique can be solved, and the area received a common service by the frequency bands of the plurality of cells together which is accepted by the terminal is improved on the premise of maintaining a mechanism for frequency space reuse and controlling interference between the adjacent cells, thereby improving the transmission rate of terminals locating at the edge of a cell.

Description

  The present invention relates to the communication field, and more particularly, to a downlink transmission system and method for borrowing spectrum resources and channel resources of neighboring cells. This downlink transmission system and method uses an adjacent cell transmission system to transmit data to the terminal of this cell in the borrowed adjacent cell spectrum.

  A core problem of inter-cell interference coordination (hereinafter abbreviated as ICIC) is to adjust the use of radio resources among a plurality of cells. In particular, it is necessary to pay attention to the cell edge. ICIC reduces interference between adjacent cells by adjusting space, time, frequency channel resources, and power among a plurality of cells.

  Time / frequency domain interference adjustment techniques can be divided into static, semi-static and dynamic time / frequency domain resource adjustments. The static type is mainly determined by the inter-cell plan at the time of the cell plan. The resource adjustment can be changed based on the load between cells and the change in business characteristics, but the cycle of this change is usually long. For the semi-static type, the resource allocation cycle is shorter than that of the static type. For dynamic adjustment methods, resources are allocated at a high frequency. The gain that can be acquired by the dynamic type is the highest, but the overhead required for measurement and information reporting is large, and it is necessary to frequently perform real-time communication between a plurality of cells.

A basic measure for solving the inter-cell interference is “Soft Frequency Reuse” or “Fractional Frequency Reuse”. This technology divides all subcarriers of an OFDM (Orthogonal Frequency Division Multiplex) system into m sets, selects different sets of subcarriers as main subcarriers of this cell for each adjacent cell, and others. Are selected as the sub-subcarriers of this cell, so that the transmission power threshold of the main subcarrier is higher than the transmission power threshold of the sub-subcarrier, and is different for the main sub-carrier and sub-subcarrier of each cell. A transmission power threshold is set, and a cell boundary is determined based on the coverage of the main subcarrier. Main subcarriers that can cover the entire cell range are allocated from the center of the cell to the edge of the cell, and subsubcarriers that cover only the inside of the cell are allocated to the empty area.
Thus, data is transmitted inside the cell mainly by sub-subcarriers with low power. Since the inside of the cell is close to the base station, the terminal can receive a clear signal from the base station of this cell. And since the power of a sub-subcarrier is small, the interference between adjacent cells is also small. On the other hand, each edge region of each adjacent cell transmits data by a main subcarrier having high power, and terminals in the edge region mainly receive main subcarriers of different adjacent cells. Since main subcarriers of different adjacent cells are orthogonal without overlapping, mutual interference can be greatly reduced.
As patent technology related to “Soft Frequency Reuse” or “Fractional Frequency Reuse”, Patent Literature 1 “Method of adjusting inter-cell interference by power planning of OFDM mobile communication system” and Patent Literature 2 “Uplink interference in a single frequency network” Adjustment method, base station, terminal and network ". This method is being studied in the current long-term development system standard for third generation mobile communications.
However, this technique has the disadvantage that the cell edge frequency resources are limited and it is difficult to support many users and high data rates.

The basic idea for alleviating the problem of cell edge frequency resource limitation in “Soft Frequency Reuse” is to improve the cell edge frequency reuse factor. That is, the edge region has a fixed reuse factor. For example, the restriction of 1/3 is released. The technical proposal “R1-051059” shown in Non-Patent Document 1 provides the idea of borrowing the frequency of an adjacent cell and improving the transmission rate of the edge terminal of this cell when the load on the adjacent cell is light. .
FIG. 1 shows a schematic diagram of the method. In this plan, the inside of the cell uses the entire frequency band with a reducible power, but the frequency reuse factor of the cell edge is not always 1/3, but is adjusted by the edge load between adjacent cells. It is. When there are few users at a certain cell edge, the available frequency is made smaller than 1/3. At the same time, when the load on the edge of the neighbor cell is heavy, the available frequency of the edge of the neighbor cell exceeds 1/3. When the user load on all the cell edges is heavy, the available frequencies of each cell edge are all 1/3.

  Referring to FIG. 1, the soft frequency reuse method used for the inter-cell edge provided by the proposal “R1-051059” is that if the edge load of the cell 1 is heavy at the first time, the neighboring cell 2, If the edge load of cells 4 and 6 is light and the edge load of cells 3, 5, and 7 is normal, the edges of cells 3, 5, and 7 still occupy the 1/3 frequency band, but cells 2, 4, 6 leaves some frequencies to be used by the edge user of the cell 1, and in this case, the frequency band occupied by the edge user of the cell 1 exceeds 1/3. If the edge load of cell 1 is normal at the Mth time, but the edge loads of its neighboring cells 2, 4, 6 are heavy and the edge loads of cells 3, 5, 7 are all light, According to this, cell 1 is assigned the original 1/3 usable frequency band, cells 3, 5 and 7 leave some frequencies and are used by the edge users of cells 2, 4 and 6, At this time, the frequency that can be used by the edge users of the cells 2, 4, and 6 exceeds the original frequency that can be used by 1/3.

In the method of transmitting data to the terminal of the present cell in the spectrum of the borrowed neighboring cell by the transmission system of the present cell described above, the borrowing of the frequency used for the edge from another cell is performed by using all the frequencies using the frequency. It is assumed that it cannot be borrowed except when the edge load of the adjacent cell is light. For example, in FIG. 1, even when the edge loads of both the cells 3 and 5 are light and there are many edge users of the cell 7 at the Mth time, the frequency cannot be borrowed from the cells 3, 5 and 7. FIG. 1 shows only the case of the structure of seven adjacent cells.
There is a similar problem in the network construction mode in which the frequency reuse factor is 1/3. When borrowing a spectrum between three neighboring cells whose operating frequencies are f1, f2, and f3, respectively, for example, when a cell with an operating frequency of f1 borrows f2, it is adjacent to a cell with an operating frequency of f1. Unless both cells f2 have a light load, they cannot be borrowed. In other words, when the edge terminal of the cell having the operating frequency f1 uses part or all of the resource block (Resource Block, RB) having the frequency f2, both of the cells adjacent to the cell having the operating frequency f1 There is a risk of interference.

Chinese patent application CN200510068133 Chinese patent application CN200610087983

3GPP R1-051059 (Inter-cell interference mitigation for EUTRA. Texas_Instruments, 3GPP RAN WG1 # 42bis, San Diego, California, US, October, 2005)

  In the present invention, when data is transmitted to a terminal of this cell in the spectrum of the borrowed neighboring cell by the transmission system of this cell, the borrowing of the spectrum is limited to a plurality of cells, and the neighboring cells of this cell interfere with each other. It is made in view of the problem of related prior art that there is a fear, and provides a technology for transmitting data to the terminal of this cell in the spectrum of the borrowed neighboring cell using the neighboring cell transmission system. Objective.

According to an aspect of the present invention, a downlink transmission system that borrows spectrum resources and channel resources of adjacent cells is provided.
In this downlink transmission system, in response to a request for frequency reuse, a plurality of adjacent or adjacent radio nodes that provide services to terminals in the service area using the same or different transmission frequency bands, and at least one terminal And there is an overlap in the area covered by the transmission signal of the adjacent wireless node. The radio node of the cell in which the terminal is located uses part or all of the resource block in the transmission channel and transmission frequency band, and the radio node of the adjacent cell in the cell in which the terminal is located is within the respective transmission channel and transmission frequency band. The business data is transmitted to the terminal by using a part or all of the resource blocks in a single stream method.

Further, in the single stream scheme, in the process of transmitting business data to the terminal, both the resource block of the radio node of the neighboring cell and the resource block of the radio node of the cell where the terminal is The data belonging to the set is loaded,
The radio node of the cell where the radio terminal is located is the control node of the radio terminal, and the control command necessary for transmission in the single stream method is transmitted between the control node and the radio terminal via the control channel therebetween. The

In the downlink transmission system, in the process of transmitting the business data to the terminal, the radio node of the adjacent cell and the radio node of the cell in which the terminal is located are based on a channel quality indication reported by the terminal, in a specific resource block. It is preferable to adjust the transmission power.
Further, in the downlink transmission system, the whole or a part of the resource block of the radio node of the adjacent cell and the all or a part of the resource block of the radio node of the cell in which the terminal is located are used simultaneously or in time division. Can send data.

  The radio node includes a remote radio unit of an independent base station and a distributed base station. The antenna of the radio node includes an antenna arranged at different sites and an antenna arranged at the same site and covering different areas. It is preferable to include.

  The terminal collectively performs down-conversion and baseband processing on signals having different frequency bands from different wireless nodes, and transmits data to be transmitted to the terminal according to the principle of linear superposition. The channel quality indication information that is selected from the data and is reported to the network side by the terminal is the channel quality indication information in the work spectrum of the radio node of the cell where the terminal is located and the channel quality indication information in the work spectrum of the radio node of the adjacent cell. Including.

  The terminal is a terminal at a cell edge.

  The resource block is either one corresponding to a spectrum in a specific time zone or one corresponding to a subcarrier group in a specific time zone in orthogonal frequency reuse.

According to another aspect of the present invention, there is provided a downlink transmission method that borrows spectrum resources and channel resources of neighboring cells.
The downlink transmission method according to the present invention includes a step of determining a set of radio nodes of neighboring cells to be preliminarily participated in a single stream transmission, and a single stream transmission from the set of radio nodes of the preliminarily neighboring cells. Selecting one or more working radio nodes to participate in and for transmitting a single stream of business data to be transmitted to the terminal, including one or more working radio nodes and the radio node of the cell in which the terminal is located A step of transmitting to the wireless node, and a step of transmitting the business data to the terminal in a single stream manner by the wireless node for single stream transmission,
In the process of transmitting business data to the terminal, the single stream scheme is configured such that a resource block of a radio node of the neighboring cell and a resource block of a radio node of the cell in which the terminal is located are set in the same transmission block. The data to which it belongs,
The radio node of the cell where the radio terminal is located is the control node of the radio terminal, and the control command necessary for transmission in the single stream method is transmitted between the control node and the radio terminal via the control channel therebetween. The

  In the step of determining a set of radio nodes of neighboring cells to be preliminarily selected, the base station sets a set of probes that specify signals transmitted from radio nodes of a specific neighboring cell, each of which includes an identification code indicator of a group of neighboring cells. To the terminal, the terminal reports the measurement result of the signal specified by the set of probes, and the network side determines whether the signal quality of the corresponding cell reaches the threshold based on the measurement result reported by the terminal. Preferably, the radio node of the cell whose signal quality has reached the threshold is determined to be the radio node of a neighboring cell to be preliminarily selected that can participate in single stream transmission.

  In the step of selecting the one or more working radio nodes, it is determined whether there is a remaining resource for the neighboring cell corresponding to the radio node of the pre-selected neighboring cell based on the overload instruction information. For each neighboring cell with remaining resources, the resource remaining amount is obtained, the application resource amount borrowed by the neighboring cell is obtained, and the residual resource amount obtained by subtracting the borrowed resource also reaches the threshold value. For neighboring cells, the radio node is preferably the working radio node.

  The step of transmitting the business data to the wireless node for single stream transmission allocates data in one transmission block set to the resource block of the wireless node for single stream transmission in the I / Q digital baseband system. It is preferable to contain.

  At least one of the above-described technical ideas of the present invention is to borrow spectrum by transmitting data to the terminal of this cell using the spectrum of the borrowed neighboring cell using the transmission system (transmission channel) of the neighboring cell. It is possible to solve the problem of related technology such that the cell is limited to a plurality of cells. In addition, by combining power control measures and dynamically adjusting the area covered by neighboring cells in common, the frequency space reuse mechanism is maintained constant and the interference between neighboring cells is controlled. However, it is possible to improve the area for receiving the joint service using the frequency bands of a plurality of cells, and improve the transmission rate of the terminal at the cell edge.

  Other features and advantages of the invention will be set forth in the specification, will be more apparent from the description, or may be further understood by practice of the invention. The objectives and other advantages of the invention may be realized and obtained by the structure particularly pointed out in the written description and claims hereof as well as the drawings.

The drawings are for further understanding of the invention and constitute a part of the specification. In addition, the present invention is interpreted together with examples of the present invention, and the present invention is not limited thereto. In the drawing
These are the figures which show the inter-cell frequency borrowing method based on related prior art. These are figures which show the downlink transmission system which concerns on the Example of this invention. These are figures which show transmission of the business data by the single stream system based on the Example of this invention. These are the flowcharts of the downlink transmission method based on the Example of this invention. FIG. 6 shows an example of downlink business transmission for spectrum borrowing of adjacent cells between nodes in a distributed base station according to an embodiment of the present invention.

  As described above, the present invention is based on the problem of related technology such that there is a limitation in spectrum borrowing when transmitting data to the terminal of this cell in the spectrum of the borrowed neighboring cell by the transmission system of this cell. It is proposed to transmit data to the terminal of this cell in the spectrum of the borrowed neighboring cell by the neighboring cell transmission system (transmission channel). In other words, in the technical idea of the present invention, the present cell borrows not only the spectrum resource of the adjacent cell but also the transmission channel of the adjacent cell.

  In the spectrum resource borrowing method, a radio terminal and a radio terminal of an adjacent cell share a cell edge spectrum resource belonging to each cell jointly by frequency hopping in a common frequency band covering spectrum resources of different cell edges. There are various things.

Moreover, although the terminal said by this invention mainly means the terminal in a cell edge, it is not limited to this.
The resource block (Resource Block, RB) referred to in the present invention includes (1) one corresponding to a spectrum in a specific time zone, and (2) a subcarrier group in a specific time zone in orthogonal frequency reuse. It may be any of those corresponding to, but is not limited to this.

  Preferred embodiments of the present invention will be described below with reference to the drawings. It should be noted that the preferred embodiments described here are merely for explaining or interpreting the present invention and are not intended to limit the present invention.

  An embodiment of the present invention provides a downlink transmission system that borrows spectrum resources and channel resources of neighboring cells. More specifically, this downlink transmission system is also referred to as a downlink single stream transmission (Single Stream Transmission) system.

  FIG. 2 shows a schematic diagram of a downlink transmission system that borrows spectrum resources and channel resources of neighboring cells according to an embodiment of the present invention. As shown in FIG. 2, the downlink transmission system includes a plurality of adjacent or adjacent radio nodes (seven radio nodes 201a to 201g in FIG. 2) and at least one terminal (radio node 201a in FIG. 2). A terminal (User Equipment, UE) 202 located in a certain cell. In response to a request for frequency reuse, a plurality of adjacent wireless nodes provide services to terminals in the service area using the same or different transmission frequency bands, and in areas covered by transmission signals of adjacent wireless nodes. There is an overlap. Reference numeral 203 denotes a service channel of the terminal, which includes a resource block (SRB) of the service cell and resource blocks (BRB1 to BRBn) of other cells borrowed.

A plurality of adjacent radio nodes provide services to terminals in the service area using the same or different transmission frequency bands in response to a request for frequency reuse. In the case of realizing frequency reuse with the adjacent cell with a reuse factor of 1, each wireless node can serve terminals in the cell with the same spectrum, and (2) wireless In the edge area of the area covered by the node, interference is generated between wireless terminals that are geographically close but belong to different cell edge areas, and each cell is different in the edge area as a method of avoiding this interference. This means that there is a method using spectrum.
However, although this method can avoid interference between edge terminals of adjacent cells, the available spectrum bandwidth of terminals in the edge region of each cell is significantly reduced. In the present invention, the basic measure for solving this problem is to improve the usable bandwidth of the edge terminal by sharing the spectrum and the transmission channel between adjacent cells. Bandwidth sharing may be performed between orthogonal (ie, exclusive) frequency bands used for the edge region of the cell or within the usable frequency band of the entire system. It depends on the actual load situation.

  The radio node of the cell in which the terminal 202 is located (for example, the radio node 201a shown in FIG. 2) uses a part or all of the resource block in the transmission channel and the transmission frequency band, and the cell adjacent to the cell in which the terminal is located. Some wireless nodes (for example, the wireless nodes 201b, 201g, 201f shown in FIG. 2) use a part of or all of the resource blocks in the respective transmission channels and transmission frequency bands, both in a single stream system. Send business data to the terminal.

  The system may transmit business data by using all or part of the resource block of the radio node of the adjacent cell and all or part of the resource block of the radio node of the cell in which the terminal is located simultaneously or in time division. it can. As an example in which the system transmits business data using all or part of the resource block of the radio node of the adjacent cell and all or part of the resource block of the radio node of the cell in which the system is time-shared, the radio terminal performs frequency hopping. (Frequency hopping) may be used to receive data from adjacent or adjacent wireless nodes.

  In the single stream method described above, in the process of transmitting business data to the terminal 202, the resource block of the wireless node of the adjacent cell (for example, the wireless nodes 201b, 201g, 201f shown in FIG. 2) and the wireless of the cell in which the terminal is located. This means that data belonging to the same set of transmission blocks is loaded in any resource block of a node (for example, the wireless node 201a shown in FIG. 2). Specifically, before transmitting data to a wireless terminal by different wireless nodes, these data are collectively subjected to orthogonal transform (for example, inverse fast Fourier transform), and the data in the same transmission block set formed is different. Assign to different frequency bands of wireless nodes and transmit.

  Specifically, FIG. 3 shows a schematic diagram for transmitting business data in a single stream method. As shown in FIG. 3, some resource blocks in a set of resource blocks SRB of a service cell (or called a main cell. For example, a cell having a radio node 201a), an adjacent cell 1 (for example, a radio node 201b). Cell) a part of resource block BRB1 in a set of resource blocks, a part of resource block BRB2 in a set of resource blocks of a neighboring cell 2 (for example, a cell having a radio node 201g),... Some resource blocks BRBn in the set of resource blocks are loaded with data in the same transmission block set.

  In order to realize flexibility, some resource blocks in the set of resource blocks (SRB) of the service cell, some resource blocks BRB1 in the set of resource blocks of neighboring cell 1, and resources of neighboring cell 2 by time division Some resource blocks BRB2,... In a set of blocks, some resource blocks BRBn in a set of resource blocks in neighboring cell n may be used, each time in one or more neighboring cells Data in the same transmission block set is transmitted using resource blocks. When data in the same transmission block set is transmitted simultaneously using resource blocks in a plurality of adjacent cells, the time difference between the resource blocks on different antennas reaching the terminal receiving antenna is different in OFDM in the usage time. It is necessary to satisfy the OFDM synchronization requirement of being smaller than the cyclic prefix of the code.

  In the process of transmitting business data to the terminal, the wireless node of the adjacent cell and the wireless node of the cell in which the terminal is located transmit in a specific resource block based on the channel quality indicator (CQI) reported by the terminal. It is preferable to adjust the power respectively.

  In the downlink transmission system, the radio node is a remote radio unit (Remote Radio Unit, RRU) of an independent base station (radio frequency and traditional base station including baseband processing). It may also be a remote radio unit of a distributed base station. The antenna of the wireless node may be an antenna arranged at a different site, or may be an antenna arranged at the same site and covering different areas (fan-shaped areas).

  The terminal 202 of this downlink transmission system includes a reception channel, a transmission channel, and a baseband processing unit. The bandwidth of the reception channel covers a part or all of the working frequency band of a cell (main cell) and an adjacent cell at the same time, and can receive signals from the main cell and the adjacent cell at the same time. The bandwidth of the transmission channel covers a part or all of the working frequency band of the cell in which the terminal is located and the adjacent cell at the same time. The terminal can collectively perform down-conversion and baseband processing on signals having different frequency bands from different radio nodes, and the data transmitted to the terminal can be transmitted to the corresponding radio according to the principle of linear superposition. Select from the transmission data of the node.

  The terminal 202 can demodulate a plurality of transmission block sets transmitted in parallel in different spectrums from signals transmitted by a plurality of adjacent wireless nodes, and synthesizes the demodulated transmission block sets into a data stream. It is preferable. Further, when the terminal 202 reports the channel quality indication information to the network side, the terminal 202 not only provides the channel quality indication information of the work spectrum of the radio node of a certain cell but also the channel quality indication of the work spectrum of the radio node of the adjacent cell. Also report information.

  An embodiment of the present invention provides a downlink transmission method that borrows spectrum resources and channel resources of neighboring cells.

  As shown in FIG. 4, the downlink transmission method includes a step S402 for determining a set of radio nodes of pre-selected neighbor cells that can participate in single stream transmission, and a set of radio nodes of pre-selected neighbor cells. Step S404 for selecting one or a plurality of working radio nodes participating in the single stream transmission, and the business data to be transmitted to the terminal, including the one or a plurality of working radio nodes and a radio node of this cell. Step S406 for transmitting to the single-stream transmission wireless node and step S408 for the single-stream transmission wireless node to transmit business data to the terminal in a single-stream manner can be provided.

  Hereinafter, each of the processing steps described above will be described in further detail.

(1) Step S402
First, the base station includes characteristic parameters of signals such as pilot signals and synchronization signals (for example, frequency points, coding schemes) transmitted from radio nodes of a specific neighboring cell, which consist of identification code indicators of a group of neighboring cells. , A set of probes (Probe Set) specifying a measurement window is transmitted to the terminal, the terminal reports the measurement result of the signal specified by the set of probes, and the network side measures the measurement reported by the terminal. Based on the result, it is determined whether or not the signal quality of the corresponding cell reaches the threshold value (or higher), and the wireless node of the cell whose signal quality has reached the threshold value can participate in single stream transmission. It is assumed that the wireless node is a neighboring cell to be preliminarily selected.
Recognizes potential neighboring cell radio nodes that can participate in single stream transmission by measuring the received power of the reference signal for switching between this cell and neighboring cells (abbreviated as Reference Symbol Received Power, RSRP). You can also

(2) Step S404
Based on the overload indication information (Overload Indication, OI) of the neighboring cell corresponding to the wireless node of the preliminarily neighboring cell, it is determined whether there is a remaining resource, and according to the OI, there is no remaining resource. In the neighboring cell that has been instructed to be overloaded, the borrowing of the frequency is abandoned, and in each of the neighboring cells with the remaining resource, the remaining amount of the resource is obtained and the application for borrowing is performed by the neighboring cell. Get the resource amount. These data can be acquired by the X2 interface between the base stations. In an adjacent cell in which the surplus resource amount obtained by subtracting resources to be borrowed also reaches a threshold value, the wireless node is set as a working wireless node.

  For resource borrowing between adjacent cells belonging to the same distributed base station, the baseband processing unit (Base Band Unit, BBU) records the load status of each cell in real time, and resource borrowing between adjacent cells is also general. Therefore, the work node can be determined without going through the X2 interface between the base stations.

(3) Step S406
The operation of transmitting the business data to the single stream transmission radio node may be to assign data in the same set of transmission blocks to each resource block of the single stream transmission radio node.

  The network side can be called a single stream transmission radio node (including the radio node of this cell and one or more working radio nodes described above), based on the resource surplus ratio of each of the radio nodes participating in the transmission, It is preferable to determine the transmission rate or the transmission amount to be borne by each wireless node, and transmit the business data to be transmitted to the terminal to each single-stream transmission wireless node (or base station).

(4) Step S408
The network or BBU sequentially transmits transmission blocks transmitted to the same wireless terminal. More specifically, the transmission of data in one transmission block set is performed by simply converting the data in one transmission block set that has undergone orthogonal transform (for example, inverse Fourier transform, IFFT), using the I / Q digital baseband method. This is performed by a method of allocating to resource blocks in one or a plurality of radio nodes determined as one stream transmission radio node.

  Based on the channel quality indicator (CQI), the network or BBU controls the spectrum transmission power and ARQ scheme for single stream transmission of each wireless node.

  The wireless terminal collectively performs down-conversion and baseband processing on signals having different frequency bands from different wireless nodes based on the principle of linear superposition represented by the following equation. Further, the data transmitted to the terminal is selected from the transmission data of the corresponding wireless node according to the principle of linear superposition represented by the following equation.

  The following further illustrates the present invention with examples.

Example: Downlink single stream service data transmission for spectrum borrowing of adjacent cells between nodes inside a distributed base station FIG. 5 is a radio access network consisting of one distributed base station. In this radio access network, at each site, three RRUs, each covering a different cell (fan area) and using different frequency bands or different orthogonal subcarrier groups in the same frequency band, are arranged as radio nodes 201. Has been. Specifically, RRU 1 covers cell 1 using frequency f1, RRU 2 covers cell 2 using frequency f2, and RRU 3 covers cell 3 using frequency f3.

  One BBU controls and processes a total of nine RRUs at the three sites, and a network is constructed between each RRU using a 1/3 frequency reuse scheme. The area covered by such a distributed base station is a control node that transmits a control command necessary for carrying out a single stream transmission with a wireless terminal via a control channel with the wireless terminal. There are a radio terminal UE1202a and a radio terminal UE2202b which are covered by three RRUs of RRU1 501a, RRU2 501b, and RRU3 501c.

  The BBU 502 implements single stream downlink transmission between the network and the wireless terminal by the downlink transmission method described in the above embodiment.

  First, in the BBU 502, RRU2 501b and RRU3 501c participate in the single stream transmission based on the measured amount of the received power (Reference symbol received power, RSRP) of the reference signal of the surrounding RRU reported by the wireless terminal 202a. It is determined that it is a potential node (that is, a radio node of the pre-selected neighbor cell described above).

  Next, the BBU 502 is instructed that there is no terminal using resources in the cells covered by the RRU2 501b and the RRU 3501c (for example, OI indicates that the load of the cell is 0. Alternatively, the BBU 502 is distributed. When performing a single stream between cells in the base station, since the load status of each RRU belonging to the BBU is stored in the BBU, the load status of each RRU belonging to the BRU via the external interface of the BBU Therefore, RRU2 501b and RRU3 501c are further determined as working nodes that perform single stream transmission to the terminal.

  Next, the BBU 502 determines the transmission rate allocated between the RRU1 501a, the RRU2 501b, and the RRU3 501c in consideration of the function of the power control element according to the loadable rate of the RRU2 501b and the RRU3 501c. .

  Finally, the BBU 502 uses the RRU1 501a, RRU2 501b, and RRU3 501c transmission channels and spectrums (that is, the above-described single-stream transmission work node), and uses the RRU1 501a, RRU2 501b, and RRU3 501c resources simultaneously or in time division. Data in the same transmission block set is transmitted to the wireless terminal using the block.

  Based on the single stream instruction information transmitted by the RRU1 501a that is the control node, the position of the resource block of each wireless node, the transmission format instruction information of the set of transmission blocks, etc., the wireless terminal Data from the wireless node belonging to the same transmission block set is demodulated and decoded.

  According to the above-described technical idea of the present invention, by using the transmission system (transmission channel) of the neighboring cell, data is transmitted to the terminal of this cell using the spectrum of the borrowed neighboring cell, so that a plurality of spectrum borrowing is performed. It is possible to solve the problem of related technology such as being limited to the number of cells. In addition, by combining power control measures and dynamically adjusting the area covered by neighboring cells in common, the frequency space reuse mechanism is maintained constant and the interference between neighboring cells is controlled. However, it is possible to improve the area for receiving the joint service using the frequency bands of a plurality of cells, and improve the transmission rate of the terminal at the cell edge.

  The above are only preferred embodiments of the present invention, and do not limit the present invention. Various modifications and variations of the present invention are possible. Any modifications, substitutions, improvements, etc. within the spirit and principle of the present invention are included in the protection scope of the present invention.

1 to 7 cells 201a to 201g wireless node 202 terminal (UE)
203 Service channel of the terminal BBU Baseband processing unit BRB1 to BRBn Resource block of other cell CQI Channel quality indicator OI Overload indication information RB Resource block RRU Remote radio unit RSRP Reference signal received power SRB Service cell resource block

Claims (13)

A plurality of adjacent or adjacent wireless nodes that provide services to terminals in the service area using the same or different transmission frequency bands in response to a request for frequency reuse, and at least one terminal, and adjacent wireless nodes A downlink transmission system that borrows spectrum resources and channel resources of adjacent cells that overlap in the area covered by the transmission signal of
The radio node of the cell in which the terminal is located uses the transmission channel and part or all of the resource blocks in the transmission frequency band, and the radio node of the cell adjacent to the cell in which the terminal is located has the respective transmission channel and transmission frequency band. Using part or all of the resource blocks in the system, both send business data to the terminal in a single stream system,
In the process of transmitting business data to the terminal, the single stream scheme is configured such that a resource block of a radio node of the neighboring cell and a resource block of a radio node of the cell in which the terminal is located are set in the same transmission block. The data to which it belongs,
The radio node of the cell where the radio terminal is located is the control node of the radio terminal, and the control command necessary for transmission in the single stream method is transmitted between the control node and the radio terminal via the control channel therebetween. The
A downlink transmission system characterized by the above. The downlink transmission system uses the whole or a part of the resource block of the radio node of the neighboring cell and the whole or a part of the resource block of the radio node of the cell in which the terminal exists, simultaneously or in time division, Send business data,
The downlink transmission system according to claim 1, wherein: In the process of transmitting business data to the terminal, the radio node of the neighboring cell and the radio node of the cell in which the terminal is located transmit power in a specific resource block based on a channel quality indication reported by the terminal. Adjust each,
The downlink transmission system according to claim 1, wherein: The radio node includes remote radio units of independent base stations and distributed base stations,
The antenna of the wireless node includes an antenna arranged at different sites and an antenna arranged at the same site and covering different areas,
The downlink transmission system according to any one of claims 1 to 3. The terminal collectively performs down-conversion and baseband processing on signals having different frequency bands from different wireless nodes, and, based on the principle of linear superposition, converts the data transmitted to the terminal to the corresponding wireless node. Select from the transmitted data,
The channel quality indication information that the terminal reports to the network side includes channel quality indication information in the working spectrum of the radio node of the cell in which the terminal is, and channel quality indication information in the working spectrum of the radio node of the adjacent cell,
The downlink transmission system according to any one of claims 1 to 3. The terminal is a terminal at a cell edge;
The downlink transmission system according to any one of claims 1 to 3. The resource block is either one corresponding to a spectrum in a specific time zone or one corresponding to a subcarrier group in a specific time zone in orthogonal frequency reuse.
The downlink transmission system according to any one of claims 1 to 3. A downlink transmission method that borrows spectrum resources and channel resources of neighboring cells,
Determining a set of pre-selected neighbor cell radio nodes that can participate in a single stream transmission;
Selecting one or more working radio nodes participating in a single stream transmission from the set of radio nodes of the pre-selected neighbor cells;
Transmitting business data to be transmitted to a terminal to a single stream transmission wireless node including the one or more working wireless nodes and a wireless node of a cell in which the terminal is located;
The wireless node for single stream transmission transmitting the business data to the terminal in a single stream scheme;
Including
In the process of transmitting business data to the terminal, the single stream scheme is configured such that a resource block of a radio node of the neighboring cell and a resource block of a radio node of the cell in which the terminal is located are set in the same transmission block. The data to which it belongs,
The radio node of the cell where the radio terminal is located is the control node of the radio terminal, and the control command necessary for transmission in the single stream method is transmitted between the control node and the radio terminal via the control channel therebetween. The
A downlink transmission method characterized by the above. Determining a set of neighbor cell radio nodes to be pre-selected,
The base station transmits to the terminal a set of probes that specify a signal transmitted from a radio node of a specific neighboring cell, which includes an identification code indicator of a group of neighboring cells.
The terminal reports the measurement result of the signal specified by the set of probes;
The network side determines whether or not the signal quality of the corresponding cell reaches the threshold based on the measurement result reported by the terminal, and transmits the radio node of the cell whose signal quality has reached the threshold to the single stream. A wireless node of a neighboring cell that can participate in
The downlink transmission method according to claim 8, wherein: In selecting the one or more working radio nodes,
For neighboring cells corresponding to the wireless nodes of the pre-selected neighboring cells, based on the overload instruction information, determine whether there is a remaining resource,
For each neighboring cell with remaining resources, obtain the remaining resource amount, obtain the application resource amount borrowed by the neighboring cells,
With respect to the neighboring cell in which the surplus resource amount obtained by subtracting the borrowed resource also reaches the threshold, the wireless node is the working wireless node.
The downlink transmission method according to claim 8 or 9, characterized by the above. The step of transmitting the business data to the wireless node for single stream transmission includes transferring data in one transmission block set to a resource block of the wireless node for single stream transmission in an I / Q digital baseband system. Including assigning,
The downlink transmission method according to claim 8, wherein: The radio terminal demodulates and decodes data belonging to the same transmission block set from one or more radio nodes based on the position of the resource block of each radio node and the transmission format indication information of the set of transfer blocks The downlink transmission system according to claim 1, wherein: After the wireless node for single stream transmission sends business data to the wireless terminal in a single stream method,
The radio terminal demodulates and decodes data belonging to the same transmission block set from one or more radio nodes based on the position of the resource block of each radio node and the transmission format indication information of the set of transfer blocks The downlink transmission method according to claim 8, wherein:

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