CN105207755B - Air interface synchronization method, base station and system - Google Patents

Abstract

The present invention discloses an air interface synchronization method, base station and system, wherein the method includes: generating a first synchronization reference signal by a first base station, wherein the first base station is one of M base stations in a small cell on the Nth floor , the first synchronization reference signal is orthogonal to the synchronization reference signals of other base stations except the first base station where the first base station is located in the N-th layer small cell; N is a positive integer greater than or equal to 2, and M is a positive integer greater than or equal to 1; the first base station sends the first synchronization reference signal in a preset synchronization subframe.

Description

Air interface synchronization method, base station and system

technical field

The invention relates to management technology in the field of communication, in particular to an air interface synchronization method, base station and system.

Background technique

The time-frequency air-interface synchronization performance of a network composed of small cells is mainly determined by the SINR distribution characteristics. In the network topology structure of multi-hop layered air interface synchronization, the interference to the synchronization signal mainly comes from the downlink data transmitted by the small cell in the adjacent layer in the listening subframe, and the cross-layer base station of N±M layer, M≥2, for N The interference of layer base station network listening can basically be ignored. Adjacent layer interference includes the interference of upper-layer Small Cells to lower-layer Small Cells, that is, multiple N-1 layer base stations send LRS signals to conflict with each other's time-frequency resources, and cause a degradation in the interception performance of a target cell on the Nth layer. It also includes the interference of the lower-layer Small Cell to the upper-layer Small Cell, that is, when a target cell of the N-th layer listens to the LRS of the N-1-th layer source cell in a certain listening subframe, it is received by the N+1-th layer eNB Interference of downlink data sent in the listening subframe.

At present, the method for solving the interference of the lower-layer Small Cells to the upper-layer Small Cells is a muting (muting) technology, that is, in the Nth listening subframe, the N+1th layer base station does not send downlink data. The above-mentioned air interface synchronization technology is mainly proposed for the application scenario of the home base station (Home eNodeB). In this application scenario, the number of base stations on the same layer in a small cluster is generally small, so the problem of mutual interference between the downlink synchronization reference signals is not very serious, that is, For a certain target cell on the Nth layer, the data of the base station sending the LRS on the N-1 layer is less. Therefore, these N-1 layer base stations can select legacy RSs with a certain frequency domain multiplexing degree (such as CRS, the multiplexing degree is 3; PRS, the multiplexing degree is 6) as LRS, and use the multiplexing of these legacyRS To achieve the time-frequency orthogonality of the LRS by means of frequency domain offset (frequency offset), so as to avoid mutual interference of LRS signals. Obviously, this method can only realize the orthogonalization of the LRS signals of a few base stations at most, for example, the maximum supported orthogonally multiplexed base station data in the same layer≤6. However, unlike the sparse deployment scenarios of Home eNodeBs, the small cell network also needs to pay attention to the application scenarios of dense deployment and even ultra-dense deployment. In the deployment scenario, when the same layer may include more than or equal to 6 Small Cell micro-stations, the upper-layer Small Cell interferes with the lower-layer Small Cell.

Contents of the invention

In view of this, the purpose of the present invention is to provide an air interface synchronization method, base station and system, which can solve the problem of interference from upper-layer small cells to lower-layer small cells.

In order to achieve the above object, technical solution of the present invention is achieved in that way:

The present invention provides an air interface synchronization method, the method comprising:

The first base station generates a first synchronization reference signal, where the first base station is one of the M base stations in the N-layer small cell, and the first synchronization reference signal and the first base station are located in the N-layer small cell . The synchronization reference signals of other base stations except the first base station are mutually orthogonal; N is a positive integer greater than or equal to 2, and M is a positive integer greater than or equal to 1;

The first base station sends the first synchronization reference signal in a preset synchronization subframe.

In the above solution, the method further includes: configuring a pattern set of the synchronization reference signal, and all the patterns in the set are orthogonal to each other on time-frequency resources;

Wherein, the orthogonal manner on the time-frequency resource includes at least one of the following:

Orthogonal multiplexing based on OFDM symbol level;

Orthogonal multiplexing based on subcarrier level;

Orthogonal multiplexing of time-frequency mixing based on preset resource unit RE pattern levels;

Correspondingly, the generating the first synchronous reference signal includes: selecting a pattern from a pattern set of synchronous reference signals to generate the first synchronous reference signal.

In the above solution, the pattern of the synchronization reference signal is that the physical resource block PRB repeats or the PRB does not repeat;

Wherein, the PRB repetition means that the RE resources of the first SRS on all PRBs are completely the same, and the PRB non-repetition means that the RE resources of the first SRS on different PRBs are not completely the same.

In the above solution, the synchronous subframe is a multicast/multicast single frequency network MBSFN subframe, or a unicast downlink subframe that does not schedule the user equipment UE.

In the above solution, the sending the first synchronization reference signal includes:

When the synchronization subframe is an MBSFN subframe, sending a first synchronization reference signal in the MBSFN domain of the MBSFN subframe;

Or, when the synchronization subframe is a unicast downlink subframe in which UE is not scheduled, the first synchronization reference signal is sent in a non-control channel region.

In the above solution, the sending of the first synchronization reference signal in the non-control channel region includes at least one of the following methods:

sending only the first synchronization reference signal in the resource region of the first synchronization reference signal;

The first synchronization reference signal avoids control channels and/or other common channel resources;

The first SRS is silenced on the control channel and/or RE resources that collide with other common channel resources.

In the above solution, the method further includes: setting a silent subframe; wherein, the silent subframe is a subframe in which a base station in a small cell on layer N-2 sends a synchronization reference signal;

Wherein, the silent subframe is a multicast/multicast single frequency network MBSFN subframe, no data is sent in the MBSFN domain; or it is a unicast downlink subframe that does not schedule UE, and no data is sent in the non-control channel area ; or ABS subframes are almost completely empty subframes.

The present invention provides an air interface synchronization method, the method comprising:

The second base station listens to the first synchronization reference signal sent by the first base station in the Nth layer small cell in the preset listening subframe; wherein, the second base station is in the N+1th layer small cell One of the L base stations; the first synchronization reference signal is orthogonal to the synchronization reference signals of other base stations except the first base station located in the N-th layer small cell of the first base station; N is greater than or equal to 2 is a positive integer, L is a positive integer greater than or equal to 1;

The second base station performs time-frequency synchronization according to the first synchronization reference signal.

In the above solution, the listening subframe is an MBSFN subframe, and no data is sent in the MBSFN domain;

Or the unicast downlink subframe of the UE is not scheduled, and no data is sent in the non-control channel region.

In the above solution, the method further includes: acquiring cell configuration information corresponding to the first base station, and determining the listening subframe according to the cell configuration information.

The present invention provides a base station, and the base station includes:

A generation unit, configured to generate a first synchronization reference signal of the base station where the base station is located, where the base station is one of the M base stations in the small cell on the Nth layer, and the first synchronization reference signal and the base station are located in the small cell on the Nth layer Among them, the synchronization reference signals of other base stations except the base station are mutually orthogonal; N is a positive integer greater than or equal to 2, and M is a positive integer greater than or equal to 1;

A sending unit, configured to send the first synchronization reference signal in a preset synchronization subframe.

In the above solution, the generating unit is further configured to configure a pattern set of the synchronous reference signal, and all the patterns in the set are orthogonal to each other on time-frequency resources; and select a pattern from the pattern set of the synchronous reference signal, for generating a first synchronization reference signal;

Wherein, the orthogonal manner on the time-frequency resource includes at least one of the following:

Orthogonal multiplexing based on OFDM symbol level;

Orthogonal multiplexing based on subcarrier level;

Orthogonal multiplexing with time-frequency mixing based on preset RE pattern levels.

In the above scheme, the pattern of the synchronization reference signal is that the physical resource block PRB is repeated, or the PRB is not repeated; wherein, the PRB repetition is that the RE resources of the first synchronization reference signal on all PRBs are completely the same, and the PRB is not repeated The RE resources for the first SRS on different PRBs are not completely the same.

In the above solution, the synchronous subframe is an MBSFN subframe or a unicast downlink subframe that does not schedule the user equipment UE.

In the above solution, the sending unit is specifically configured to send the first synchronization reference signal in the MBSFN field of the MBSFN subframe when the synchronization subframe is an MBSFN subframe;

Or, when the synchronization subframe is a unicast downlink subframe in which UE is not scheduled, the first synchronization reference signal is sent in a non-control channel region.

In the above solution, the sending of the first synchronization reference signal in the non-control channel region includes at least one of the following methods:

sending only the first synchronization reference signal in the resource region of the first synchronization reference signal;

The first synchronization reference signal avoids control channels and/or other common channel resources;

The first synchronization reference signal is silenced on the control channel and/or other common channel resources, conflicting RE resources.

In the above scheme, the generating unit is further configured to set a silent subframe; wherein, the silent subframe is a subframe in which a base station in a small cell on layer N-2 sends a synchronization reference signal;

Wherein, the silent subframe is an MBSFN subframe, and does not send data in the MBSFN domain; or is a unicast downlink subframe that does not schedule UE, and does not send any data in a non-control channel area; or is an ABS subframe.

The present invention also provides a base station, and the base station includes:

The listening unit is set at the base station, and is used to listen to the first synchronization reference signal sent by the first base station in the small cell of the Nth layer in the preset listening subframe; wherein, the second base station is the first One of the L base stations in the N+1 layer small cell; the first synchronization reference signal and the synchronization reference signals of the first base station located in the Nth layer small cell and other base stations except the first base station are mutually positive Intersection; N is a positive integer greater than or equal to 2, L is a positive integer greater than or equal to 1;

A synchronization unit, configured to implement time-frequency synchronization according to the second synchronization reference signal.

In the above solution, the listening subframe is an MBSFN subframe, and no data is sent in the MBSFN domain;

Or the unicast downlink subframe of the UE is not scheduled, and no data is sent in the non-control channel region.

In the above solution, the base station further includes: a setting unit, configured to obtain cell configuration information corresponding to the first base station, and determine the listening subframe according to the cell configuration information.

The present invention provides an air interface synchronization system, the system comprising:

The first base station is set in the small cell on the Nth layer, and is used to generate a first synchronization reference signal, and send the first synchronization reference signal in a preset synchronization subframe; wherein, the first synchronization reference signal is located at the Nth layer. In the layer small cell, the synchronization reference signals of other base stations except the first base station are orthogonal to each other; N is a positive integer greater than or equal to 2;

The second base station is set in the N+1th layer small cell, and is used to listen to the first synchronization reference signal sent by the first base station in the Nth layer small cell in the preset listening subframe; according to the The first synchronization reference signal is used for time-frequency synchronization.

The air interface synchronization method, base station and system provided by the present invention can ensure that when sending a synchronization signal, it is in an orthogonal state with the synchronization signals of other base stations on its own layer, so that the base station in the small cell of the next layer is receiving the synchronization signal , it will not be interfered by the synchronization signals of other base stations on the upper layer. In this way, the problem of interference from small cells on the upper layer to small cells on the lower layer is solved.

Description of drawings

FIG. 1 is a first schematic flow diagram of an air interface synchronization method in an embodiment of the present invention;

FIG. 2 is a schematic diagram of a frame structure in an air interface synchronization method in an embodiment of the present invention;

FIG. 3 is a second schematic flow diagram of an air interface synchronization method in an embodiment of the present invention;

FIG. 4a is a first schematic diagram of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

FIG. 4b is a second schematic diagram of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

FIG. 5a is a third schematic diagram of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

FIG. 5b is a fourth schematic diagram of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

FIG. 6a is a fifth schematic diagram of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

FIG. 6b is a sixth schematic diagram of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

Fig. 7a is a schematic diagram 7 of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

Fig. 7b is a schematic diagram 8 of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

Fig. 8a is a schematic diagram 9 of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

FIG. 8b is a tenth schematic diagram of orthogonal multiplexing of synchronous reference signals provided by an embodiment of the present invention;

FIG. 9 is a first structural diagram of a base station according to an embodiment of the present invention;

FIG. 10 is a second schematic diagram of the structure of a base station according to an embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment one,

The air interface synchronization method provided in this embodiment is applied to the first base station, as shown in FIG. 1 , including:

Step 101: The first base station generates a first synchronization reference signal, wherein the first base station is one of M base stations in the Nth layer, and the first synchronization reference signal and the first base station are located in the Nth layer, except Synchronization reference signals of other base stations other than the first base station are orthogonal to each other;

Step 102: The first base station sends the first synchronization reference signal in a preset synchronization subframe.

Here, before the execution of step 101, the method further includes: configuring a pattern set of the first synchronization reference signal, and all patterns in the set are mutually orthogonal on time-frequency resources;

Wherein, the orthogonal manner on the time-frequency resource may include at least one of the following: Orthogonal Multiplexing based on Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) symbol level; Orthogonal Multiplexing based on subcarrier level Use; Orthogonal multiplexing of time-frequency mixing based on preset RE pattern levels.

Correspondingly, the generating the first synchronous reference signal includes: selecting a pattern from a pattern set of synchronous reference signals to generate the first synchronous reference signal. Wherein, the selection may be selecting a pattern that has not been selected by other base stations in the layer.

Further explanation of the pattern of the first synchronization reference signal (LRS): it can be PRB repetition, that is, on the preset synchronization subframe, the LRS on all PRBs are the same; it can also be PRB non-repetition , that is, on the preset synchronous subframe, RE resources of LRS signals on different PRBs may be different. For the latter case, all RE resources on multiple PRBs together form an LRS pattern.

The preset synchronization subframe may be a multicast/multicast single frequency network (MBSFN) subframe and/or a unicast downlink subframe that does not schedule the UE;

Correspondingly, the sending the first synchronization reference signal includes: when the synchronization subframe is a multicast/multicast single frequency network (MBSFN, Multicast Broadcast Single Frequency Network) subframe, in the MBSFN subframe The MBSFN domain sends a dedicated synchronization reference signal;

Or, when the synchronization subframe is a unicast downlink subframe in which UE is not scheduled, a dedicated synchronization reference signal is sent in a non-control channel region.

Wherein, the sending the first synchronization reference signal in the non-control channel region includes at least one of the following methods:

sending only the first synchronization reference signal in the resource region of the first synchronization reference signal;

The first synchronization reference signal avoids control channels and/or other common channel resources;

The first synchronization reference signal is silenced on the control channel and/or other common channel resources, conflicting RE resources.

The foregoing sending of the first synchronization reference signal may include: sending the first synchronization reference signal to a second base station, so that the second base station implements time-frequency synchronization according to the first synchronization reference signal; wherein, the first The second base station is one of the L base stations in the N+1 layer of the small cell.

Preferably, the above solution may further include: setting a silent subframe; wherein, the silent subframe is a subframe in which a base station in a small cell on layer N-2 sends a synchronization reference signal. The aforementioned silent subframe is an MBSFN subframe, or a unicast downlink subframe for which no UE is scheduled, or an almost blank subframe (ABS) subframe.

Preferably, the above method may further include: the first base station listening to the dedicated synchronization reference signal sent by the upper layer in the MBSFN domain of the MBSFN subframe.

The possible selection methods for the base stations of multiple N-layer small cells to select the style of the first synchronization reference signal (LRS) include:

Configured through a centralized controller base station (which can be a logical unit);

Through the backhaul signaling interaction, the first base station queries the LRS patterns of other base stations at the same layer through the backhaul interface, and configures its own LRS pattern accordingly. In particular, when there are many eNBs at the same layer, the first base station may further limit the set range of synchronous base stations that it refers to. The limiting method can be obtained by exchanging each other's location information, or the first base station listens to the RS signals of other eNBs at the same layer, and performs RSRP measurement, and assists in judging who is the neighboring eNB according to the RSRP measurement result.

Figure 2 is a schematic diagram of the frame structure of the layer where the first base station is located and the adjacent two layers in the air interface synchronization method proposed by this patent, where the D (downlink) subframe is a synchronization subframe, and the L (Network Listening) subframe is a listening subframe frame, M (Muting) is a silent subframe. It is assumed that M base stations on the Nth layer transmit synchronous reference signals that are time-frequency orthogonal to each other in the same synchronous subframe; they also listen to the synchronous reference signals sent by the base stations on the N-1th layer in the same synchronization subframe to achieve their own time-frequency synchronization; The transmission of its own data is suspended in the subframe in which the base station on layer N-2 sends the synchronization reference signal, so as to avoid interfering with the base station on the upper layer (such as layer n-1) to listen to the time-frequency synchronization signal.

It can be seen that through the above scheme, when sending the synchronization signal, it can be guaranteed to be in an orthogonal state with the synchronization signals of other base stations on its own layer, so that the base station in the small cell of the next layer will not be affected by other synchronization signals when receiving the synchronization signal. The interference of the synchronization signal of the base station on the first floor, in this way, the problem of interference from the small cells of the upper layer to the small cells of the lower layer is solved.

Embodiment two,

The air interface synchronization method provided in this embodiment is applied to the second base station, as shown in FIG. 3 , including:

Step 301: The second base station listens to the first synchronization reference signal sent by the first base station in the Nth layer small cell in the preset listening subframe; wherein, the second base station is the N+1th layer One of the L base stations in the small cell; the first synchronization reference signal is orthogonal to the synchronization reference signals of other base stations except the first base station that the first base station is located in the Nth-layer small cell; N is A positive integer greater than or equal to 2, L is a positive integer greater than or equal to 1;

Step 302: The second base station performs time-frequency synchronization according to the first synchronization reference signal.

The listening subframe is an MBSFN subframe, and no data is sent in the MBSFN domain;

Or the unicast downlink subframe of the UE is not scheduled, and no data is sent in the non-control channel region.

Preferably, the above solution may further include: stopping sending data in a preset silent subframe; wherein the silent subframe is a subframe in which the base station in the N-2 layer small cell sends the synchronization reference signal. The above silent subframes are MBSFN subframes, or unicast downlink subframes that do not schedule UEs, and do not send any data or ABS subframes in the non-control channel region.

If the first base station uses the MBSFN subframe to send the first synchronization reference signal, the second base station uses the MBSFN domain of the designated MBSFN subframe as the listening subframe to detect the first synchronization reference signal sent by the first base station ;

If the synchronization subframe used by the first base station is a unicast downlink subframe that does not schedule UEs, the method may further include: the second base station also needs to obtain cell configuration information corresponding to the first base station, according to the The cell configuration information determines the listening subframe; wherein, the cell configuration information may include the number of symbols occupied by the PDCCH, the time-frequency positions of the CRS and the CSI-RS, and the like. The cell configuration information can be obtained through backhaul signaling detection and/or receiver blind detection.

Figure 2 is a schematic diagram of the frame structure of the layer where the first base station is located and the adjacent two layers in the air interface synchronization method proposed by this patent, where the D (downlink) subframe is a synchronization subframe, and the L (Network Listening) subframe is a listening subframe frame, M (Muting) is a silent subframe. It is assumed that M base stations on the Nth layer transmit synchronous reference signals that are time-frequency orthogonal to each other in the same synchronous subframe; they listen to the synchronous reference signals sent by the base stations on the N-1th layer at the same time to achieve their own time-frequency synchronization; The transmission of its own data is suspended in the subframe in which the base station on layer N-2 sends the synchronization reference signal, so as to avoid interfering with the base station on the upper layer (such as layer n-1) to listen to the time-frequency synchronization signal.

The method for generating the second synchronization reference signal may include at least one of the following: orthogonal multiplexing based on OFDM symbol level; orthogonal multiplexing based on subcarrier level; Cross multiplexing.

The OFDM symbol level-based orthogonal multiplexing provided in this embodiment is described below in conjunction with FIG. 4a, FIG. 4b and FIG. 5a, FIG. 5b:

Wherein, when the synchronization subframe is a multicast/multicast single frequency network (MBSFN) subframe, as shown in Figure 4a, the synchronization subframe 411 of the Mth base station in the Nth layer is shown, and Figure 4b shows the Lth base station in the Nth layer Synchronous subframes 412, these two synchronous subframes are orthogonal to each other.

As shown in Figure 5a, when the synchronization subframe is a unicast downlink subframe that does not schedule UEs and when the location of the time-frequency resource (ie, RE) to be occupied by the synchronization reference signal is the same as that of the cell common reference signal (such as CRS, CSI-RS, etc. ) 51 conflict, then only the first synchronization reference signal is sent in the resource area of the first synchronization reference signal; or the first synchronization reference signal avoids control channel and/or other common channel resources; or the first synchronization reference signal The synchronization reference signal is silenced on the control channel and/or other common channel resources, conflicting RE resources. Figure 5a shows the synchronization subframe 521 of the Mth base station in the Nth layer, and Figure 5b shows the synchronization subframe 522 of the Lth base station in the Nth layer, and these two synchronization subframes are mutually orthogonal.

It can be understood that the sequences of the synchronization reference signals sent by multiple base stations on the same layer may be different, and may be a certain sequence with good correlation and cross-correlation characteristics. In addition, the synchronization reference signals sent by multiple base stations 1 on the same layer occupy different OFDM symbols.

The subcarrier-level-based SRS orthogonal multiplexing provided in this embodiment is described below in conjunction with FIG. 6a, FIG. 6b and FIG. 7a, FIG. 7b:

Wherein, when the synchronization subframe is a multicast/multicast single frequency network (MBSFN) subframe, as shown in Figure 6a, the synchronization subframe 611 of the Mth base station in the Nth layer is shown, and Figure 6b shows the Lth base station in the Nth layer Synchronous subframe 612, these two synchronous subframes are orthogonal to each other.

As shown in Figure 7a, when the synchronization subframe is a unicast downlink subframe that does not schedule UEs and when the location of the time-frequency resource (ie, RE) to be occupied by the synchronization reference signal is the same as that of the cell common reference signal (such as CRS, CSI-RS, etc. ) 72 when a collision occurs, only the cell common reference signal is sent, as shown in Figure 7a, the synchronization subframe 711 of the Mth base station in the Nth layer, and Figure 7b shows the synchronization subframe 712 of the Lth base station in the Nth layer, which The two synchronization subframes are orthogonal to each other.

It can be understood that the sequences of the synchronization reference signals sent by multiple base stations on the same layer may be different, and may be a certain sequence with good correlation and cross-correlation characteristics. In addition, the synchronization reference signals sent by multiple base stations on the same layer occupy different subcarriers.

The RE pattern level-based synchronous reference signal time-frequency hybrid orthogonal multiplexing provided by this embodiment is described below in conjunction with FIG. 8a and FIG. 8b:

In principle, the orthogonal multiplexing signal can be distributed in the entire synchronization reference signal area with RE as the smallest unit, without being limited to occupying the entire OFDM symbol or subcarrier. However, in order to reduce signaling overhead, it is preferable to define a limited number of time-frequency synchronization patterns, so as to indicate which time-frequency synchronization pattern a specific Small Cell occupies with a small signaling overhead.

A preferred time-frequency synchronization pattern is shown in 8a, and the synchronization reference signal occupies one or more OFDM symbols according to a specific signal-to-noise ratio requirement. On each OFDM symbol, the SRS only occupies part of the subcarriers. In particular, the synchronization reference signals are uniformly distributed across the subcarriers with equal subcarrier spacing. When the synchronization subframe 82 is a unicast downlink subframe that does not schedule UEs and when the time-frequency resource (ie, RE) position to be occupied by the synchronization reference signal conflicts with the cell common reference signal (such as CRS, CSI-RS, etc.), Then only the cell common reference signal is sent.

The SRS sequences sent by multiple Small Cells on the same layer are different, and may be a certain sequence with good correlation and cross-correlation characteristics. The time-frequency patterns of the synchronization reference signals sent by multiple Small Cells in the same layer have no overlapping area with each other.

It can be seen that through the above scheme, the synchronization signal can be made to be in an orthogonal state with the synchronization signals of other base stations on its own layer, so that when the base station in the small cell of the lower layer receives the synchronization signal, it will not be affected by other base stations on the upper layer. The interference of the synchronization signal, in this way, solves the problem of interference from the small cells in the upper layer to the small cells in the lower layer.

In addition, the above-mentioned solution can also be combined with improved interception silence and interference suppression silence technologies, so that the air interface synchronization technology proposed in this patent solution can still work normally in densely deployed Small Cell and ultra-densely deployed scenarios, and obtain higher Time-frequency synchronization performance.

Embodiment three,

This embodiment provides a base station. As shown in FIG. 9, the base station includes:

The generating unit 901 is configured to generate a first synchronization reference signal of the base station where the base station is located, where the base station is one of the M base stations in the small cell on the Nth floor, and the first synchronization reference signal and the base station are located in the small cell on the Nth floor In the cell, the synchronization reference signals of other base stations except the base station are orthogonal to each other; N is a positive integer greater than or equal to 2, and M is a positive integer greater than or equal to 1;

The sending unit 902 is configured to send the first synchronization reference signal in a preset synchronization subframe.

The generating unit is further configured to configure a pattern set of the synchronous reference signal, and all the patterns in the set are orthogonal to each other on time-frequency resources; and select a pattern from the pattern set of the synchronous reference signal to generate the first a synchronization reference signal;

Wherein, the orthogonal manner on the time-frequency resource includes at least one of the following:

Orthogonal multiplexing based on OFDM symbol level;

Orthogonal multiplexing based on subcarrier level;

Orthogonal multiplexing with time-frequency mixing based on preset RE pattern levels.

The synchronous subframe is an MBSFN subframe and a unicast downlink subframe that does not schedule the user equipment UE.

The sending unit 902 is specifically configured to send a dedicated synchronization reference signal in the MBSFN field of the MBSFN subframe when the synchronization subframe is an MBSFN subframe;

Or, when the synchronization subframe is a unicast downlink subframe in which UE is not scheduled, a dedicated synchronization reference signal is sent in a non-control channel region.

The generating unit 901 is further configured to stop sending data in a preset silent subframe; wherein the silent subframe is a subframe in which a base station in a small cell on layer N-2 sends a synchronization reference signal.

The sending the first synchronization reference signal in the non-control channel region includes at least one of the following methods:

sending only the first synchronization reference signal in the resource region of the first synchronization reference signal;

The first synchronization reference signal avoids control channels and/or other common channel resources;

The first synchronization reference signal is silenced on the control channel and/or other common channel resources, conflicting RE resources.

Figure 2 is a schematic diagram of the frame structure of the layer where the first base station is located and the adjacent two layers in the air interface synchronization method proposed by this patent, where the D (downlink) subframe is a synchronization subframe, and the L (Network Listening) subframe is a listening subframe frame, M (Muting) is a silent subframe. It is assumed that M base stations on the Nth layer transmit synchronous reference signals that are time-frequency orthogonal to each other in the same synchronous subframe; they listen to the synchronous reference signals sent by the base stations on the N-1th layer at the same time to achieve their own time-frequency synchronization; The transmission of its own data is suspended in the subframe in which the base station on layer N-2 sends the synchronization reference signal, so as to avoid interfering with the base station on the upper layer (such as layer n-1) to listen to the time-frequency synchronization signal.

It can be seen that through the above scheme, when sending the synchronization signal, it can be guaranteed to be in an orthogonal state with the synchronization signals of other base stations on its own layer, so that the base station in the small cell of the next layer will not be affected by other synchronization signals when receiving the synchronization signal. The interference of the synchronization signal of the base station on the first floor, in this way, the problem of interference from the small cells of the upper layer to the small cells of the lower layer is solved.

Embodiment four,

A base station provided in this embodiment, as shown in FIG. 10, the base station includes:

The listening unit 1001 is set at the base station, and is used to listen to the first synchronization reference signal sent by the first base station in the N-th layer small cell in the preset listening subframe; wherein, the second base station is One of the L base stations in the N+1-th layer small cell; the first synchronization reference signal interacts with the synchronization reference signals of the first base station located in the N-th layer small cell and other base stations except the first base station Orthogonal; N is a positive integer greater than or equal to 2, L is a positive integer greater than or equal to 1;

The synchronization unit 1002 is configured to implement time-frequency synchronization according to the second synchronization reference signal.

The base station also includes: a processing unit 1003, configured to stop sending data in a preset silent subframe; wherein, the silent subframe is a subframe in which the base station in the N-2 layer small cell sends a synchronization reference signal frame.

The base station further includes: a setting unit 1004, configured to acquire cell configuration information corresponding to the first base station. In addition, the location of the listening subframe is determined according to the cell configuration information. For example, if the synchronization subframe used by the first base station is a unicast downlink subframe that does not schedule UEs, cell configuration information may be sent, wherein the cell The configuration information may include the number of symbols occupied by the PDCCH, the time-frequency positions of the CRS and the CSI-RS, and the like. The cell configuration information can be obtained through backhaul signaling detection and/or receiver blind detection.

The method for generating the second synchronization reference signal may include at least one of the following: orthogonal multiplexing based on OFDM symbol level; orthogonal multiplexing based on subcarrier level; Cross multiplexing.

The OFDM symbol level-based orthogonal multiplexing provided in this embodiment is described below in conjunction with FIG. 4a, FIG. 4b and FIG. 5a, FIG. 5b:

Wherein, when the synchronization subframe is a multicast/multicast single frequency network (MBSFN) subframe, as shown in Figure 4a, the synchronization subframe 411 of the Mth base station in the Nth layer is shown, and Figure 4b shows the Lth base station in the Nth layer Synchronous subframes 412, the two synchronous subframes are orthogonal to each other.

As shown in Figure 5a, when the synchronization subframe is a unicast downlink subframe that does not schedule UEs and when the location of the time-frequency resource (ie, RE) to be occupied by the synchronization reference signal is the same as that of the cell common reference signal (such as CRS, CSI-RS, etc. ) 51 when conflict occurs, only the common reference signal of the cell is sent, as shown in Figure 5a, the synchronization subframe 521 of the Mth base station in the Nth layer, and Figure 5b shows the synchronization subframe 522 of the Lth base station in the Nth layer, this The two synchronization subframes are orthogonal to each other.

It can be understood that the sequences of the synchronization reference signals sent by multiple base stations on the same layer may be different, and may be a certain sequence with good correlation and cross-correlation characteristics. In addition, the synchronization reference signals sent by multiple base stations 1 on the same layer occupy different OFDM symbols.

The subcarrier-level-based SRS orthogonal multiplexing provided in this embodiment is described below in conjunction with FIG. 6a, FIG. 6b and FIG. 7a, FIG. 7b:

Wherein, when the synchronization subframe is a multicast/multicast single frequency network (MBSFN) subframe, as shown in Figure 6a, the synchronization subframe 611 of the Mth base station in the Nth layer is shown, and Figure 6b shows the Lth base station in the Nth layer Synchronous subframe 612, these two synchronous subframes are orthogonal to each other.

As shown in Figure 7a, when the synchronization subframe is a unicast downlink subframe that does not schedule UEs and when the location of the time-frequency resource (ie, RE) to be occupied by the synchronization reference signal is the same as that of the cell common reference signal (such as CRS, CSI-RS, etc. ) 72 when a collision occurs, only the cell common reference signal is sent, as shown in Figure 7a, the synchronization subframe 711 of the Mth base station in the Nth layer, and Figure 7b shows the synchronization subframe 712 of the Lth base station in the Nth layer, which The two synchronization subframes are orthogonal to each other.

It can be understood that the sequences of the synchronization reference signals sent by multiple base stations on the same layer may be different, and may be a certain sequence with good correlation and cross-correlation characteristics. In addition, the synchronization reference signals sent by multiple base stations on the same layer occupy different subcarriers.

The RE pattern level-based synchronous reference signal time-frequency hybrid orthogonal multiplexing provided by this embodiment is described below in conjunction with FIG. 8a and FIG. 8b:

In principle, the orthogonal multiplexing signal can be distributed in the entire synchronization reference signal area with RE as the smallest unit, without being limited to occupying the entire OFDM symbol or subcarrier. However, in order to reduce signaling overhead, it is preferable to define a limited number of time-frequency synchronization patterns, so as to indicate which time-frequency synchronization pattern a specific Small Cell occupies with a small signaling overhead.

A preferred time-frequency synchronization pattern is shown in 8a, and the synchronization reference signal occupies one or more OFDM symbols according to a specific signal-to-noise ratio requirement. On each OFDM symbol, the SRS only occupies part of the subcarriers. In particular, the synchronization reference signals are evenly distributed across the subcarriers with equal subcarrier spacing. When the synchronization subframe 82 is a unicast downlink subframe that does not schedule UEs and when the time-frequency resource (ie, RE) position to be occupied by the synchronization reference signal conflicts with the cell common reference signal (such as CRS, CSI-RS, etc.), Then only the cell common reference signal is sent.

The SRS sequences sent by multiple Small Cells on the same layer are different, and may be a certain sequence with good correlation and cross-correlation characteristics. The time-frequency patterns of the synchronization reference signals sent by multiple Small Cells in the same layer have no overlapping area with each other.

It can be seen that through the above scheme, the synchronization signal can be made to be in an orthogonal state with the synchronization signals of other base stations on its own layer, so that when the base station in the small cell of the lower layer receives the synchronization signal, it will not be affected by other base stations on the upper layer. The interference of the synchronization signal, in this way, solves the problem of interference from the small cells in the upper layer to the small cells in the lower layer.

In addition, the above-mentioned solution can also be combined with improved interception silence and interference suppression silence technologies, so that the air interface synchronization technology proposed in this patent solution can still work normally in densely deployed Small Cell and ultra-densely deployed scenarios, and obtain higher Time-frequency synchronization performance.

Preferably, the embodiment of the present invention also provides an air interface synchronization system, the system comprising:

The first base station is set in the small cell on the Nth layer, and is used to generate a first synchronization reference signal, and send the first synchronization reference signal in a preset synchronization subframe; wherein, the first synchronization reference signal is located at the Nth layer. In the layer small cell, the synchronization reference signals of other base stations except the first base station are orthogonal to each other; N is a positive integer greater than or equal to 2;

The second base station is set in the N+1th layer small cell, and is used to listen to the first synchronization reference signal sent by the first base station in the Nth layer small cell in the preset listening subframe; according to the The first synchronization reference signal is used for time-frequency synchronization.

In the several embodiments provided in this application, it should be understood that the disclosed devices and methods may be implemented in other ways. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods, such as: multiple units or components can be combined, or May be integrated into another system, or some features may be ignored, or not implemented. In addition, the coupling, or direct coupling, or communication connection between the components shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be electrical, mechanical or other forms of.

The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units; Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present invention can be integrated into one processing module, or each unit can be used as a single unit, or two or more units can be integrated into one unit; the above-mentioned integration The unit can be realized in the form of hardware or in the form of hardware plus software functional unit.

Those of ordinary skill in the art can understand that all or part of the steps for realizing the above-mentioned method embodiments can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the Including the steps of the foregoing method embodiments; and the foregoing storage medium includes: a removable storage device, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, etc. A medium on which program code can be stored.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone skilled in the art can easily think of changes or substitutions within the technical scope disclosed in the present invention. Should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (17)

1. a kind of air interface synchronization method, which is characterized in that the described method includes:

First base station generates the first synchronous reference signal, wherein and the first base station is one of M base station in n-th layer cell, The synchronous reference of first synchronous reference signal and other base stations in n-th layer cell, in addition to the first base station Signal is mutually orthogonal；N is the positive integer more than or equal to 2, and M is the positive integer more than or equal to 1；

The first base station sends first synchronous reference signal in preset synchronous subframe；

Silent subframe is set；The silence subframe is the subframe of the base station transmission synchronous reference signal in N-2 layers of cell； Wherein, the silent subframe is multicast/multicast single-frequency network network MBSFN sub-frame, does not send data in the domain MBSFN；Or for not The unicast downlink subframe of UE is dispatched, and does not send any data in non-control channel region；It or is almost full empty frame ABS Frame.

2. the method according to claim 1, wherein the method also includes: configure the sample of synchronous reference signal Formula set, and pattern all in the set is orthogonal mutually on running time-frequency resource；

Wherein, mode orthogonal on the running time-frequency resource comprises at least one of the following:

Based on the other orthogonal multiplex of orthogonal frequency division multiplex OFDM symbol level；

Based on the other orthogonal multiplex of sub-wave length；

Orthogonal multiplex based on the other time-frequency mixing of preset resource unit RE pattern level；

Correspondingly, the first synchronous reference signal of the generation includes: one sample of selection from the pattern set of synchronous reference signal Formula, for generating the first synchronous reference signal.

3. according to the method described in claim 2, it is characterized in that, the pattern of the synchronous reference signal is Physical Resource Block PRB is repeated or PRB is not repeated；

Wherein, the PRB repetition is that the RE resource of the first synchronous reference signal on all PRB is identical, and the PRB is not weighed RE resource again for the first synchronous reference signal on different PRB is not exactly the same.

4. the method according to claim 1, wherein the synchronous subframe is multicast/multicast single-frequency network network MBSFN Subframe or the unicast downlink subframe for not dispatching user equipment (UE).

5. according to the method described in claim 4, it is characterized in that, transmission first synchronous reference signal includes:

When the synchronous subframe is MBSFN sub-frame, the first synchronous reference signal is sent in the domain MBSFN of the MBSFN sub-frame；

Alternatively, it is same to send first in non-control channel region when the synchronous subframe is not dispatch the unicast downlink subframe of UE Walk reference signal.

6. according to the method described in claim 5, it is characterized in that, described send the first synchronous reference in non-control channel region Signal comprises at least one of the following mode:

The first synchronous reference signal is only sent in the resource area of first synchronous reference signal；

First synchronous reference signal avoids control channel and/or other common channel resources；

First synchronous reference signal is silent in control channel and/or the RE resource of other common channel resources conflicts.

7. a kind of air interface synchronization method, which is characterized in that the described method includes:

Second base station is listened in subframe preset, listens to the first synchronous reference that the first base station in n-th layer cell is sent Signal；Wherein, second base station is one of L base station in N+1 layers of cell；First synchronous reference signal be located at The synchronous reference signal of other base stations in n-th layer cell, in addition to the first base station is mutually orthogonal；N is more than or equal to 2 Positive integer, L are the positive integer more than or equal to 1；

Second base station carries out Time and Frequency Synchronization according to first synchronous reference signal；Wherein the subframe of listening to is MBSFN Subframe, and data are not sent in the domain MBSFN；

Or not dispatch the unicast downlink subframe of UE, and any data are not sent in non-control channel region.

8. being listened to the method according to the description of claim 7 is characterized in that second base station is listened in subframe preset Before the first synchronous reference signal that first base station in n-th layer cell is sent, the method also includes: obtain described first The corresponding community configured information in base station listens to subframe according to community configured information determination.

9. a kind of base station, which is characterized in that the base station includes:

Generation unit, the first synchronous reference signal for base station where generating, wherein the base station is M in n-th layer cell One of a base station, first synchronous reference signal are same with other base stations in n-th layer cell, in addition to the base station It is mutually orthogonal to walk reference signal；N is the positive integer more than or equal to 2, and M is the positive integer more than or equal to 1；

Transmission unit, for sending first synchronous reference signal in preset synchronous subframe；

The generation unit is also used to be arranged silent subframe；Wherein, the silent subframe is the base in N-2 layers of cell It stands and sends the subframe of synchronous reference signal；Wherein, the silent subframe is MBSFN sub-frame, and does not send number in the domain MBSFN According to；The unicast downlink subframe of UE is not either dispatched, and does not send any data in non-control channel region；Either ABS Frame.

10. base station according to claim 9, which is characterized in that the generation unit is also used to configure synchronous reference signal Pattern set, and pattern all in the set is orthogonal mutually on running time-frequency resource；And the sample from synchronous reference signal One style is chosen in formula set, for generating the first synchronous reference signal；

Wherein, mode orthogonal on the running time-frequency resource comprises at least one of the following:

Orthogonal multiplex based on OFDM symbol rank；

Based on the other orthogonal multiplex of sub-wave length；

Orthogonal multiplex based on the other time-frequency mixing of preset RE pattern level.

11. base station according to claim 10, which is characterized in that the pattern of the synchronous reference signal is Physical Resource Block PRB is repeated or PRB is not repeated；

Wherein, the PRB repetition is that the RE resource of the first synchronous reference signal on all PRB is identical, and the PRB is not weighed RE resource again for the first synchronous reference signal on different PRB is not exactly the same.

12. base station according to claim 10, which is characterized in that the synchronous subframe is MBSFN sub-frame or does not dispatch use The unicast downlink subframe of family equipment UE.

13. base station according to claim 9, which is characterized in that the transmission unit is specifically used for working as the synchronous subframe When for MBSFN sub-frame, the first synchronous reference signal is sent in the domain MBSFN of the MBSFN sub-frame；

Alternatively, it is same to send first in non-control channel region when the synchronous subframe is not dispatch the unicast downlink subframe of UE Walk reference signal.

14. base station according to claim 13, which is characterized in that described to send the first synchronous ginseng in non-control channel region It examines signal and comprises at least one of the following mode:

The first synchronous reference signal is only sent in the resource area of first synchronous reference signal；

First synchronous reference signal avoids control channel and/or other common channel resources；

First synchronous reference signal is silent on control channel and/or other common channel resources, the RE resource of conflict.

15. a kind of base station, which is characterized in that the base station is the second base station, and second base station includes:

Unit is listened to, for listening in subframe preset, it is synchronous to listen to the first base station in n-th layer cell is sent first Reference signal；Wherein, second base station is one of L base station in N+1 layers of cell；First synchronous reference signal with The synchronous reference signal of other base stations in n-th layer cell, in addition to the first base station is mutually orthogonal；N be greater than etc. In 2 positive integer, L is the positive integer more than or equal to 1；

Synchronization unit, for carrying out Time and Frequency Synchronization according to first synchronous reference signal；

Wherein, the subframe of listening to is MBSFN sub-frame, and does not send data in the domain MBSFN；

Or not dispatch the unicast downlink subframe of UE, and any data are not sent in non-control channel region.

16. base station according to claim 15, which is characterized in that the base station further include: setting unit, for obtaining The corresponding community configured information of first base station is stated, subframe is listened to according to community configured information determination.

17. a kind of air interface synchronization system, which is characterized in that the system comprises:

First base station is set to n-th layer cell, for generating the first synchronous reference signal, sends in preset synchronous subframe First synchronous reference signal；Wherein, first synchronous reference signal be located at n-th layer cell in, remove described first The synchronous reference signal of other base stations outside base station is mutually orthogonal；N is the positive integer more than or equal to 2；

Silent subframe is set；The silence subframe is the subframe of the base station transmission synchronous reference signal in N-2 layers of cell； Wherein, the silent subframe is multicast/multicast single-frequency network network MBSFN sub-frame, does not send data in the domain MBSFN；Or for not The unicast downlink subframe of UE is dispatched, and does not send any data in non-control channel region；It or is almost full empty frame ABS Frame；

Second base station is set to N+1 layers of cell, for listening in subframe preset, listens in the small cell of n-th layer The first synchronous reference signal that one base station is sent；According to first synchronous reference signal, Time and Frequency Synchronization is carried out；

Wherein the subframe of listening to is MBSFN sub-frame, and does not send data in the domain MBSFN；

Or not dispatch the unicast downlink subframe of UE, and any data are not sent in non-control channel region.