CN105634697A - Method and apparatus for configuring signal parameters in radio-interface based synchronization mechanism (RIBS) - Google Patents

Abstract

The invention provides a method and apparatus for configuring signal parameters in a radio-interface based synchronization mechanism (RIBS). The method for configuring the signal parameters in the RIBS comprises the steps of configuring source cells of the same layer with reference signals as LRSs, wherein the LRSs of the source cells of the same layer are the same, configuring the LRSs transmitted by the source cells of the same layer with the same sub frame offset, and configuring the LRSs transmitted by source cells of different layers with different sub frame offsets; and controlling the source cells, based on the sub frame offsets of the configured LRSs, to transmit the LRSs to corresponding sub frame positions. By configuring the source cells of the same layer with the same LRSs as the reference signals, the scheme enables the LRSs transmitted by the source cells of the same layer to be enhanced in terms of mutual additivity so as to obtain signal diversity gains, in this way, the problems of interference, due to the RE resource conflict, among LRSs (LRS, listening RS) transmitted by the plurality of source cells of different layers in ultra-dense small cell deployment scenarios in the prior art are solved, and the network RIBS performance is improved.

Description

Method and device for configuring signal parameters in air interface synchronization

Technical Field

The present invention relates to the field of wireless technologies, and in particular, to a method and an apparatus for configuring signal parameters in air interface synchronization.

Background

In order to suppress the inter-station interference, the TDD base stations deployed with the same frequency need to perform inter-station time-frequency synchronization. The 3GPP preferentially supports 3 inter-station time-frequency synchronization schemes: (1) satellite synchronization such as GPS synchronization based on GNSS (global navigation satellite system); (2) based on ideal backhaul network synchronization, such as IEEE1588v2 synchronization; (3) air-interface based synchronous (RIBS for short). In typical LTE application scenarios (such as HomeeNodeB, NanoCell, and SmallCell) such as indoor and high-rise hot spot coverage, GPS signals are not easy to acquire, and ideal backhaul is difficult to guarantee, so that an air interface synchronization technology needs to be researched.

Currently, 3GPP focuses on an air interface synchronization technology called network interception (NW), and the basic principle thereof is as follows: the base station to be synchronized (called target base station or targetcell) listens to the LRS of the synchronized base station (called source base station or sourcecell), and adjusts the local clock accordingly to maintain the time-frequency synchronization between the stations.

The 3GPP has studied the RIBS technology (radio interface based synchronization technology) in the early days for home base station (HomeeNB) scenarios, and the basic idea is as follows:

(1) without defining a new listeningRS, an existing reference signal (e.g., cell common reference signal CRS) is used as listeningRS, so that the listeningRS sequences sent by different sourcecells are different (scrambled by cellID);

(2) an eNB (called targetcell) newly accessing a synchronous network selects a certain base station (called sourcecell) as a synchronous source of the eNB, namely a targetcell only monitors listeningRS of one sourcecell;

(3) considering the multi-hop synchronization scenario, it is not set that the targetcellT1 (synchronization level n) listens to the CRS of sourcecellS1 (synchronization level n-1) at the subframe M for synchronization tracking. T1 may listen to other signals (including LRS or traffic data transmitted by other base stations) besides the LRS transmitted in S1 in the mth subframe, so that the network listening performance is affected, and there are 2 main interference types:

a) interference of downlink signals of the (n + 1) th layer base station on the nth layer interception subframe;

b) interference of downlink signals (possibly LRS) transmitted by base stations except for S1 at layer n-1 to LRS of S1;

(4) for the first kind of interference, 3GPP proposes a cross-subframe muting mechanism to solve;

(5) for the second type of interference, 3GPP has not discussed. review 3GPP documentation from other companies, one potential trending view is: multiple sourcecells in the same layer transmit respective LRSs in the same downlink subframe, and the LRSs are legacy rss (e.g., CRS, positioning reference signals PRS), so the sequences of the LRSs are different. Obviously, when the number of nodes of the same layer sourcecell is small, these LRSs can be staggered in the frequency domain (e.g. by frequency shift technology) to avoid mutual interference of the same layer LRS signals.

In particular, in the HomeeNB and current smallcell deployment scenarios, the total number of eNB nodes within one cluster is limited, with a typical value of 8. If the system supports 3 hops, there are 2-3 base stations in each hop (layer). These base stations in the same layer respectively transmit LRS signals (such as CRS or PRS sequences) scrambled by their cellids on the same subframe, and these LRS signals may be staggered on RE resources through cell planning.

However, for a future more dense deployment scenario of smallcells (micro stations) (such as 5GUDN: ultra dense network), more than 60 smallcells may exist in one cluster, and more than 7 smallcells may exist in each hop (layer). If the existing RIBS technology is adopted, that is, the base stations in the same layer respectively transmit the LRS signals scrambled by their respective cellids on the same subframe, because the number of sourcecells in the same layer exceeds the multiplexing degree of the LRS signals (for example, the multiplexing degree of CRS signals of 2 ports is 3, and the multiplexing degree of PRS signals is 6), the LRS signals are difficult to be completely staggered on RE resources even through cell planning, and therefore, the LRS signals interfere with each other and reduce the synchronization performance of the network air interface.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a method and an apparatus for configuring signal parameters in air interface synchronization, which solve the problem of mutual interference caused by RE resource conflict of synchronization reference signals (LRS, listeningrss) sent by multiple sourcecells on the same layer in a smallcell super-dense deployment scenario in the prior art.

In order to solve the foregoing technical problem, an embodiment of the present invention provides a method for configuring a signal parameter in air interface synchronization, where the method includes:

configuring a reference signal serving as an LRS for a same-layer source base station, wherein the LRS of the same-layer source base station is the same;

configuring the same subframe offset for the LRS sent by the source base stations at the same layer, and configuring different subframe offsets for the LRS sent by the source base stations at different layers;

and controlling each source base station to send the LRS at the corresponding subframe position based on the subframe offset of the LRS configured by the source base station.

The above configuration method, wherein the configuring the reference signal as the LRS for the same-layer source base station includes:

any one of CRS, PRS and CSI-RS is configured as a reference signal of an LRS of a same-layer source base station, and the same initial phase is configured for the any one of the reference signals.

The above configuration method, wherein the configuring the same initial phase for the arbitrary reference signal includes:

the base station related parameters in the initial phase calculation formula are replaced with the radio frame number to generate the same initial phase.

The invention also provides a method for configuring signal parameters in air interface synchronization, which comprises the following steps:

receiving the same LRS from a plurality of source base stations in the same layer;

acquiring the sending time of a source base station corresponding to each LRS from the LRSs, wherein the sending time of the source base station takes a source base station clock as a reference;

obtaining local receiving time corresponding to a plurality of LRSs when the LRSs arrive, wherein the local receiving time takes a local clock as a reference;

and calculating by using the sending time and the local receiving time of the source base station corresponding to the LRSs to obtain an average timing deviation estimated value.

The foregoing configuration method, wherein before calculating by using the source base station transmission time and local reception time corresponding to each of the LRSs to obtain an average timing deviation estimated value, the method further includes:

obtaining path propagation delay time corresponding to each of the LRSs;

the calculating to obtain the average timing deviation value by using the source base station sending time and the local receiving time corresponding to the LRSs specifically includes:

and calculating by using the sending time, the local receiving time and the path propagation delay time of the source base station corresponding to the LRSs to obtain an average timing deviation value.

The invention also provides a method for configuring signal parameters in air interface synchronization, which comprises the following steps:

configuring an LRS mode for a base station to ensure that the LRS sent by the base station is orthogonal to LRSs sent by other base stations in the same layer;

transmitting the cell-scrambled LRS according to the LRS mode.

In the configuration method, the LRS sent by the base station and LRS sent by other base stations in the same layer are respectively located in GP of different special subframes in the TDD system.

The aforementioned configuration method, wherein the configuring an LRS mode for the base station includes:

sending a signaling for requesting feedback of the used LRS mode to an adjacent base station in the same layer;

receiving response information fed back by the adjacent base station according to the signaling;

and acquiring an LRS mode which is different from LRS modes of all adjacent base stations in a local LRS mode database according to the response information.

The aforementioned configuration method, wherein the configuring an LRS mode for the base station includes:

determining a candidate subframe of an LRS to be transmitted;

monitoring LRSs sent by other adjacent cells on the candidate subframes;

if the interception result is that the candidate subframe has LRS configuration resources which are not occupied by LRSs of other adjacent cells, determining an unoccupied LRS configuration resource;

and determining an LRS mode according to the determined LRS configuration resource.

The configuration method further includes:

and if the interception result is that all the available LRS configuration resources of the candidate subframe are occupied by the LRSs of the other adjacent cells, continuing to execute the determination of the candidate subframe of the LRS to be sent.

In the above configuration method, in the same cluster, the transmission periods of all LRSs are the same; if the micro station has the switch conversion function, the LRS is also sent even if the micro station is in a dormant state; the LRS has a characteristic point different from other signals and can be identified by other neighboring cells.

The invention also provides a device for configuring signal parameters in air interface synchronization, which comprises:

a first configuration module, configured to configure a reference signal as an LRS for a same-layer source base station, where the LRSs of the same-layer source base station are the same;

a second configuration module, configured to configure the same subframe offset for the LRS sent by the source base stations on the same layer, and configure different subframe offsets for the LRS sent by the source base stations on different layers;

and the control module is used for controlling each source base station to send the LRS at the corresponding subframe position based on the subframe offset of the LRS configured by the source base station.

The above configuration device, wherein the first configuration module comprises:

a first configuration unit, configured to configure any one of a CRS, a PRS, and a CSI-RS as a reference signal of an LRS of a peer source base station;

and the second configuration unit is used for configuring the same initial phase for the arbitrary reference signal.

The above configuration device, wherein the second configuration unit includes:

a replacing component for replacing the base station related parameter in the initial phase calculation formula with the radio frame number to generate the same initial phase.

The invention also provides a device for configuring signal parameters in air interface synchronization, which comprises:

a receiving module, configured to receive the same LRS from multiple source base stations on the same layer;

a first obtaining module, configured to obtain, from the LRSs, source base station sending time corresponding to each LRS, where the source base station sending time is based on a source base station clock;

a second obtaining module, configured to obtain local receiving times corresponding to arrival of the LRSs, where the local receiving times are based on a local clock;

and the operation module is used for performing operation by utilizing the source base station sending time and the local receiving time corresponding to the LRSs to obtain an average timing deviation estimated value.

The above configuration device further includes:

a third obtaining module, configured to obtain, before the operation module performs an operation, path propagation delay times corresponding to the LRSs;

the operation module is specifically configured to:

and calculating by using the sending time, the local receiving time and the path propagation delay time of the source base station corresponding to the LRSs to obtain an average timing deviation value.

The invention also provides a device for configuring signal parameters in air interface synchronization, which comprises:

a third configuration module, configured to configure an LRS mode for the base station, so that the LRS sent by the base station is orthogonal to LRSs sent by other base stations in the same layer;

a sending module, configured to send the cell-scrambled LRS according to the LRS mode.

In the configuration apparatus, the LRS transmitted by the base station and LRS transmitted by other base stations in the same layer are respectively located in GP of different special subframes in the TDD system.

The above configuration device, wherein the third configuration module comprises:

a first sending unit, configured to send a signaling requesting feedback of an LRS mode used to a neighboring base station in the same layer;

a receiving unit, configured to receive response information fed back by the neighboring base station according to the signaling;

and the obtaining unit is used for obtaining an LRS mode which is different from LRS modes of all adjacent base stations in the local LRS mode database according to the response information.

The above configuration device, wherein the third configuration module comprises:

a first determining unit, configured to determine a candidate subframe of an LRS to be transmitted;

a second sending unit, configured to listen to LRSs sent by other neighboring cells on the candidate subframe;

a second determining unit, configured to determine an unoccupied LRS configuration resource if the listening result indicates that the LRS configuration resource unoccupied by the LRS of the other neighboring cell exists in the candidate subframe;

a third determining unit, configured to determine an LRS mode according to the determined LRS configuration resource.

The above configuration device further includes:

and a circulating module, configured to continue to determine a candidate subframe of an LRS to be transmitted if the listening result indicates that all available LRS configuration resources of the candidate subframe are occupied by LRSs of other neighboring cells.

In the foregoing configuration device, in the same cluster, transmission periods of all LRSs are the same; if the micro station has the switch conversion function, the LRS is also sent even if the micro station is in a dormant state; the LRS has a characteristic point different from other signals and can be identified by other neighboring cells.

The technical scheme of the invention has the following beneficial effects:

in the above scheme, the method for configuring signal parameters in air interface synchronization configures the same LRS as a reference signal for the same-layer source base station, so that LRS signals sent by the same-layer source base station are additively enhanced to obtain signal diversity gain, or configures different LRS modes for the same-layer source base station, so that LRS signals sent by the same-layer source base station are orthogonal, thereby solving the problem of mutual interference caused by RE resource conflict of synchronization reference signals (LRS, listeningRS) sent by multiple sourcecells on the same layer in a smallcell ultra-dense deployment scenario in the prior art, and improving the air interface synchronization performance of the network.

Drawings

Fig. 1 is a first schematic step diagram of a method for configuring signal parameters in air interface synchronization according to an embodiment of the present invention;

fig. 2 is a schematic diagram illustrating a second step of a method for configuring signal parameters in air interface synchronization according to an embodiment of the present invention;

fig. 3 is a third schematic step diagram of a method for configuring signal parameters in air interface synchronization according to an embodiment of the present invention;

fig. 4 is a first schematic structural diagram of a configuration apparatus for signal parameters in air interface synchronization according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a configuration apparatus for signal parameters in air interface synchronization according to an embodiment of the present invention;

fig. 6 is a third schematic structural diagram of a configuration apparatus for signal parameters in air interface synchronization according to an embodiment of the present invention;

FIG. 7 is a diagram illustrating multi-hop synchronization according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of the principle of Methoda according to an embodiment of the present invention;

FIG. 9 is a first schematic diagram illustrating the principle of MethodB according to an embodiment of the present invention;

FIG. 10 is a second schematic diagram of the principle of MethodB according to the embodiment of the present invention;

fig. 11 is a schematic diagram illustrating an air interface synchronization principle applied in the embodiment of the present invention;

FIG. 12 is a schematic diagram of the principle of a method according to an embodiment of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

The present invention provides a method for configuring signal parameters in air interface synchronization, aiming at the problem of mutual interference caused by RE resource conflict of synchronization reference signals (LRS, listeningRS) sent by multiple sourcecells at the same layer in an smallcell ultra-dense deployment scenario in the prior art, as shown in fig. 1, the method includes:

step 11: configuring a reference signal serving as an LRS for a same-layer source base station, wherein the LRS of the same-layer source base station is the same;

step 12: configuring the same subframe offset for the LRS sent by the source base stations at the same layer, and configuring different subframe offsets for the LRS sent by the source base stations at different layers;

step 13: and controlling each source base station to send the LRS at the corresponding subframe position based on the subframe offset of the LRS configured by the source base station.

In the method for configuring signal parameters in air interface synchronization provided in the embodiment of the present invention, the same LRS is configured for the same-layer source base station as a reference signal, so that LRS signals sent by the same-layer source base station are additively enhanced to each other to obtain a signal diversity gain, thereby solving a problem in the prior art that synchronization reference signals (LRS, listeningrss) sent by multiple sourcecells at the same layer interfere with each other due to RE resource collision in a smallcell super-dense deployment scenario, so as to improve a network air interface synchronization performance.

Specifically, a preferred method for configuring the reference signal as the LRS for the peer source base station is to configure any one of CRS (Cell-specific reference signal), PRS (positioning reference signal), and CSI-RS (csireference signals, CSI is an abbreviation of Channel-state information), as the reference signal of the LRS for the peer source base station, and configure the same initial phase for the any one of the reference signals.

It is not excluded to design a new reference signal, and when the new reference signal is configured as a reference signal of the LRS of the same-layer source base station, the sequence generation manner and the initial phase are completely the same.

Wherein configuring the same initial phase for the arbitrary reference signal comprises: the base station related parameters in the initial phase calculation formula are replaced with the radio frame number to generate the same initial phase.

Preferably, for CRS and PRS, the Cell-ID parameter is replaced by the radio frame numberFor CSI-RS, replacing parameters of higher layer configuration with radio frame number

In order to solve the foregoing technical problem, an embodiment of the present invention further provides a method for configuring a signal parameter in air interface synchronization, where as shown in fig. 2, the method includes:

step 21: receiving the same LRS from a plurality of source base stations in the same layer;

step 22: acquiring the sending time of a source base station corresponding to each LRS from the LRSs, wherein the sending time of the source base station takes a source base station clock as a reference;

step 23: obtaining local receiving time corresponding to a plurality of LRSs when the LRSs arrive, wherein the local receiving time takes a local clock as a reference;

step 24: and calculating by using the sending time and the local receiving time of the source base station corresponding to the LRSs to obtain an average timing deviation estimated value. Wherein the estimated value comprises a measurement error value.

The method for configuring signal parameters in air interface synchronization provided by the embodiment of the invention further solves the problem of mutual interference of synchronization reference signals (LRS, listeningRS) sent by a plurality of sourcecells on the same layer in an ultra-dense deployment scene of a smallcell in the prior art due to RE resource conflict by processing LRS sent by a plurality of source base stations on the same layer to obtain an average timing deviation estimated value, so as to improve the air interface synchronization performance of a network.

Before obtaining an average timing deviation estimated value by performing an operation using the source base station transmission time and local reception time corresponding to each of the plurality of LRSs, the method further includes: obtaining path propagation delay time corresponding to each of the LRSs; the calculating to obtain the average timing deviation value by using the source base station sending time and the local receiving time corresponding to the LRSs specifically includes: and calculating by using the sending time, the local receiving time and the path propagation delay time of the source base station corresponding to the LRSs to obtain an average timing deviation value.

In order to solve the foregoing technical problem, an embodiment of the present invention further provides a method for configuring a signal parameter in air interface synchronization, where as shown in fig. 3, the method includes:

step 31: configuring an LRS mode for a base station to ensure that the LRS sent by the base station is orthogonal to LRSs sent by other base stations in the same layer;

step 32: transmitting the cell-scrambled LRS according to the LRS mode.

According to the method for configuring signal parameters in air interface synchronization provided by the embodiment of the invention, different LRS modes are configured for the same-layer source base station, so that LRSs transmitted mutually are orthogonal, and the problem of mutual interference of synchronization reference signals (LRS, listeningRS) transmitted by a plurality of sourcecells at the same layer in an ultra-dense deployment scene of a smallcell in the prior art due to RE resource conflict is solved, so that the air interface synchronization performance of a network is improved.

The LRS sent by the base station and LRSs sent by other base stations in the same layer are respectively located in GP of different special subframes in the TDD system.

The invention preferentially adopts a distributed LRS mode scheduling mechanism, and specifically has two implementation forms, namely: the configuring an LRS mode for the base station includes: sending a signaling for requesting feedback of the used LRS mode to an adjacent base station in the same layer; receiving response information fed back by the adjacent base station according to the signaling; and acquiring an LRS mode which is different from LRS modes of all adjacent base stations in a local LRS mode database according to the response information.

And the second method comprises the following steps: the configuring method provided by the embodiment of the present invention, wherein the configuring an LRS mode for the base station includes: determining a candidate subframe of an LRS to be transmitted; monitoring LRSs sent by other adjacent cells on the candidate subframes; if the interception result is that the candidate subframe has LRS configuration resources which are not occupied by LRSs of other adjacent cells, determining an unoccupied LRS configuration resource; and determining an LRS mode according to the determined LRS configuration resource.

Further, if the interception result is that all available LRS configuration resources of the candidate subframe are occupied by LRSs of other neighboring cells, the candidate subframe of an LRS to be transmitted is determined continuously.

Wherein, in the same cluster, the transmission periods of all LRSs are the same; if the micro station has the switch conversion function, the LRS is also sent even if the micro station is in a dormant state; the LRS has a characteristic point different from other signals and can be identified by other neighboring cells.

In order to solve the foregoing technical problem, an embodiment of the present invention further provides a device for configuring a signal parameter in air interface synchronization, where as shown in fig. 4, the device includes:

a first configuration module, configured to configure a reference signal as an LRS for a same-layer source base station, where the LRSs of the same-layer source base station are the same;

a second configuration module, configured to configure the same subframe offset for the LRS sent by the source base stations on the same layer, and configure different subframe offsets for the LRS sent by the source base stations on different layers;

and the control module is used for controlling each source base station to send the LRS at the corresponding subframe position based on the subframe offset of the LRS configured by the source base station.

The device for configuring signal parameters in air interface synchronization provided in the embodiment of the present invention configures the same LRS for the same-layer source base station as the reference signal, so that LRS signals sent by the same-layer source base station are additively enhanced to obtain the signal diversity gain, thereby solving the problem of mutual interference caused by RE resource collision between synchronization reference signals (LRS, listeningrss) sent by multiple sourcecells at the same layer in a smallcell super-dense deployment scenario in the prior art, and improving the network air interface synchronization performance.

Specifically, the first configuration module includes: a first configuration unit, configured to configure any one of CRS (Cell-specific reference signal), PRS (positioning reference signal), and CSI-RS (csireferencessignals, where CSI is an abbreviation of Channel-state information, and RS is an abbreviation of reference signal) as a reference signal of an LRS of a peer source base station; and the second configuration unit is used for configuring the same initial phase for the arbitrary reference signal.

It is not excluded to design a new reference signal, and when the new reference signal is configured as a reference signal of the LRS of the same-layer source base station, the sequence generation manner and the initial phase are completely the same.

Wherein the second configuration unit includes: a replacing component for replacing the base station related parameter in the initial phase calculation formula with the radio frame number to generate the same initial phase.

Preferably, for CRS and PRS, the Cell-ID parameter is replaced by the radio frame numberFor CSI-RS, replacing parameters of higher layer configuration with radio frame number

In order to solve the foregoing technical problem, an embodiment of the present invention further provides a device for configuring a signal parameter in air interface synchronization, as shown in fig. 5, including:

a receiving module, configured to receive the same LRS from multiple source base stations on the same layer;

a first obtaining module, configured to obtain, from the LRSs, source base station sending time corresponding to each LRS, where the source base station sending time is based on a source base station clock;

a second obtaining module, configured to obtain local receiving times corresponding to arrival of the LRSs, where the local receiving times are based on a local clock;

and the operation module is used for performing operation by utilizing the source base station sending time and the local receiving time corresponding to the LRSs to obtain an average timing deviation estimated value. Wherein the estimated value comprises a measurement error value.

The configuration device for signal parameters in air interface synchronization provided in the embodiment of the present invention obtains an average timing deviation estimated value by processing LRSs sent by multiple same-layer source base stations, and further solves the problem of mutual interference caused by RE resource collision of synchronization reference signals (LRSs, listeningrss) sent by multiple same-layer source cells in a small cell super-dense deployment scenario in the prior art, so as to improve the network air interface synchronization performance.

Wherein, still include: a third obtaining module, configured to obtain path propagation delay time corresponding to each of the LRSs before the operation module performs the operation;

the operation module is specifically configured to: and calculating by using the sending time, the local receiving time and the path propagation delay time of the source base station corresponding to the LRSs to obtain an average timing deviation value.

In order to solve the foregoing technical problem, an embodiment of the present invention further provides a device for configuring a signal parameter in air interface synchronization, as shown in fig. 6, including:

a third configuration module, configured to configure an LRS mode for the base station, so that the LRS sent by the base station is orthogonal to LRSs sent by other base stations in the same layer;

a sending module, configured to send the cell-scrambled LRS according to the LRS mode.

The device for configuring signal parameters in air interface synchronization provided by the embodiment of the invention enables the LRSs sent by each other to be orthogonal by configuring different LRS modes for the same-layer source base station, so that the problem of mutual interference of synchronization reference signals (LRS, listeningrss) sent by multiple sourcecells at the same layer in an ultra-dense deployment scene of a smallcell in the prior art due to RE resource conflict is solved, and the air interface synchronization performance of a network is improved.

The LRS sent by the base station and LRSs sent by other base stations in the same layer are respectively located in GP of different special subframes in the TDD system.

The invention preferentially adopts a distributed LRS mode scheduling mechanism, and specifically has two implementation forms, namely: the third configuration module comprises: a first sending unit, configured to send a signaling requesting feedback of an LRS mode used to a neighboring base station in the same layer; a receiving unit, configured to receive response information fed back by the neighboring base station according to the signaling; and the obtaining unit is used for obtaining an LRS mode which is different from LRS modes of all adjacent base stations in the local LRS mode database according to the response information.

Second, the third configuration module in the configuration apparatus provided in the embodiment of the present invention includes: a first determining unit, configured to determine a candidate subframe of an LRS to be transmitted; a second sending unit, configured to listen to LRSs sent by other neighboring cells on the candidate subframe; a second determining unit, configured to determine an unoccupied LRS configuration resource if the listening result indicates that the LRS configuration resource unoccupied by the LRS of the other neighboring cell exists in the candidate subframe; a third determining unit, configured to determine an LRS mode according to the determined LRS configuration resource.

Further, the method also comprises the following steps: and a circulating module, configured to continue to determine a candidate subframe of an LRS to be transmitted if the listening result indicates that all available LRS configuration resources of the candidate subframe are occupied by LRSs of other neighboring cells.

Wherein, in the same cluster, the transmission periods of all LRSs are the same; if the micro station has the switch conversion function, the LRS is also sent even if the micro station is in a dormant state; the LRS has a characteristic point different from other signals and can be identified by other neighboring cells.

The following describes a configuration method of the signal parameter in the air interface synchronization according to an embodiment of the present invention.

And (2) transmitting the completely same LRS signals in the same LRS transmission subframe by a plurality of sourcecells in the same layer, namely the LRS signals of the cells in the same layer have the same pseudo code sequence and occupy the same RE resource.

The basic principle is as follows:

multiple sourcecells in the same layer transmit completely same LRS signals in the same LRS transmission subframe, that is, the LRS signals of the cells in the same layer have the same pseudo code sequence and occupy the same RE resource.

the targetcell carries out network listening in the LRS sending subframe, and the received signal is a superposition of LRS signals (called as LRS components) sent by a plurality of sourcecells on a time domain.

the targetcell estimates the arrival Time (TOA) of all LRS components through a time domain correlation operation (or other similar operation), but because the pseudo code sequences of all LRS components are the same, the targetcell cannot correctly identify from which sourcecell these LRS components with different arrival times are specifically emitted.

Focusing on the node eNB2-2 with stratumlevel 2 in fig. 7, it receives LRS signals of three sourcecells (eNB 1-1, eNB1-2, and eNB1-3, respectively) of the previous hop (stratumlevel 1) at the same time in the LRS transmission subframe with stratumlevel 1. These LRS signals have the same pseudo code sequence, and time-frequency resources.

For simplicity of description, sourcecelleNB1-1, eNB1-2, and eNB1-3 are denoted as S1, S2, and S3, respectively, and targetcelleNB2-2 is denoted as targetcellT. As shown in fig. 8, sourcecellS1, S2, and S3 all transmit an LRS signal at local time 0(LRS transmission subframe). Due to the timing synchronization errors of S1, S2 and S3, the actual sending time of the LRS signal is t respectively by using GNSS timing (GNSStiming) as reference timing (referrence timing)_TX1＝_S1、t_TX2＝_S2And t_TX3＝_S3. Meanwhile, the initial timing synchronization error of targetcellT is assumed to be t_target＝_T. Consider the path propagation delays τ to targetcellT of S1, S2, and S3_S1、τ_S2And τ_S3Then, the arrival times of the LRS signals transmitted at S1, S2, and S3 expressed in GNSS time to reach targetcellT are t_RX1＝_S1+τ_S1、t_RX2＝_S2+τ_S2And t_RX3＝_S3+τ_S3。

the signal received by targetcellT is actually a combination of S1, S2 and S3 in time domain of sending LRS signals, and the arrival time of each LRS component expressed in GNSS time is shown as an image on the corresponding axis of receiversigT in FIG. 8, which is t_RX1＝_S1+τ_S1、t_RX2＝_S2+τ_S2And t_RX3＝_S3+τ_S3。

As shown in fig. 8, the time of arrival (TOA) of the signal represented by targetcell local time of each received signal component is TOA_RX1＝t_RX1-t_target＝(_S1-_T)+τ_S1、TOA_RX2＝t_RX2-t_target＝(_S2-_T)+τ_S2And TOA_RX3＝t_RX3-t_target＝(_S3-_T)+τ_S3。

the targetcellT first generates a local recurring signal replica of the LRS, and then performs time-domain correlation (or other similar operations) on the replica and the received signal to obtain a synthetic correlation function, synthetic acf, whose curve is shown as the image on the corresponding axis of the synthetic acft in fig. 8. The horizontal axis position corresponding to the peak value of the ACF function represents the signal propagation time represented by targetcell local time. By the position of the peak of the ACF function, the estimated amount of the signal arrival time TOA expressed as targetcell local time can be estimatedNamely, it isWherein_S1、_S2And_S3representing the TOA estimation error (i.e., measurement error). Can assume that_S1、_S2And_S3independently distributed and mean 0.I.e. the raw moveout measurements obtained by targetcellAmount of the compound.

the targetcellT finally generates the estimated value of the timing deviation according to the TOA information of each LRS component and some other auxiliary informationSo that it is approximately equal to the average timing offset of the last hop source base station. When obtaining a timing deviation estimatorThereafter, targetcell in accordance withAnd calibrating the local clock to make the average timing deviation of the local clock approximately equal to the average timing deviation of the last-hop source base station, namely realizing the clock synchronization function of the adjacent 2-hop base station.

Propagation delay tau when path of all sourcecells_SiCan be completely ignored, haveAndthe timing offset of targetcell can now be estimated by simple arithmetic averaging, i.e.

Timing relation:

timing offset estimator:

wherein,representing definitions, E { □ } representing averaging, and E ∑ representing the mean value of the measurement noise_Si0. The physical meaning of the above formulaIs, when the path propagates the delay τ_SiWhen it can be ignored, the timing offset of targetcell can be estimatedDefined as the mean of the TOAAnd a timing offset estimator calculated according to the definitionApproximately equal to targetcell's true timing offset_TMean value E of timing deviation from all source base stations of last hop_SiThe difference. To obtainThereafter, targetcell adjusts the local clockBiasing calibrated local clock timingE, being approximately equal to the mean value of the timing deviations of all source base stations of the last hop_SiI.e. that ${\mathrm{\δ}}_T^{\mathrm{correct}}\stackrel{\mathrm{\Δ}}{=}{\mathrm{\δ}}_T-{\widehat{\mathrm{\δ}}}_T=E\left\{{\mathrm{\δ}}_{\mathrm{Si}}\right\}.$

However, the path propagation delay τ when sourcecell_SiLarger, not negligible, then simply T cannot be passedOA is the timing deviation estimator for estimating targetcell by averaging algorithmHowever, in the MethodA, because the LRS sequences of all LRS components are the same, it is difficult for targetcellT to associate the LRS components with a specific sourcecell, i.e., to utilize a priori information (e.g., the path propagation delay τ)_Si) The TOA estimate of the LRS component is calibrated (meaning that the path propagation delay τ is calibrated)_SiEffect on TOA measurement). Tau when some sourcecell paths propagate_SiLarger, may cause larger system bias to the targetcellT timing offset estimation algorithm. Different timing deviation estimation methods will be given according to 3 different application scenarios.

Sourcecell side treatment:

sourcecells of the same stratumlevel use the same LRS subframe offset (subframe offset), while different stratumlevels use different LRSsubframeoffset.

The sourcecells with the same stratumlevel send completely same LRS signals in the same LRS sending subframe, that is, the LRS signals of the cells in the same layer have the same pseudo code sequence and occupy the same RE resource. Therefore, the LRS signal here is independent of cellID.

One embodiment is to scramble the LRS by radio frame number (SFN) instead of cellID.

For example, when the LRS signal is CSI-RS (csireferences, CSI is an abbreviation of Channel-state information, and RS is an abbreviation of reference signal), the initial phase (initial phase calculation formula) of the pseudo code sequence thereof is

$c_{\mathrm{init}}=2^{10}\·(7\·(n_s+1)+l+1)\·(2\·N_{\mathrm{ID}}^{\mathrm{CSI}}+1)+2\·N_{\mathrm{ID}}^{\mathrm{CSI}}+N_{\mathrm{CP}},$

Wherein, $N_{\mathrm{CP}}=\left\{\begin{array}{cc}1& \mathrm{for\; normal\; CP}\\ 0& \mathrm{for\; extended\; CP}\end{array}\right.$

wherein n is_sIs the slot number within the radio frame (slot number with associated audio frame), is the OFDM symbol number within one slot (OFDM symbol),numbering CSI for the cell; n is a radical of_CPFor cyclic prefix type parameters, when a normal cyclic prefix (normal CP) is used, N_CPOtherwise, when an extended cyclic prefix (extendedCP) is used, N_CP＝0；c_initIs the initial phase of the pseudorandom sequence.

Can be used forConfigured to SFN number through higher layer signaling. This embodiment does not require modification of existing standards.

In embodiment 2, when the LRS signal is CRS (Cell-specific reference signal) or PRS (positioning reference signal), the initial phase (initial phase calculation formula) of the pseudo code sequence is CRS

$c_{\mathrm{init}}=2^{10}\·(7\·(n_s+1)+l+1)\·(2\·N_{\mathrm{ID}}^{\mathrm{cell}}+1)+2\·N_{\mathrm{ID}}^{\mathrm{cell}}+N_{\mathrm{CP}}$

The main parameters are the same as above, the main difference isRepresenting a cell number (cellID). This embodiment requires modification of the initial phase cinit of the LRS generation sequenceParameter(s) ofModified to SFN number.

Similar configurations are possible if the LRS uses other reference signals.

Targetcell side processing:

according to different deployment scenarios of the smallcell, the processing mode of the targetcell side is different. There may be 3 types of main deployment scenarios:

in the first type of deployment scenario, all targetcells can always find a sourcecell which is very close to the targetcell, and the path propagation delay between the targetcell and the sourcecell is negligible.

According to the assumption, the shortest path propagation delay tau from all source base stations of the (n-1) th hop to the (n) th hop targetcell_S1Neglectable, the timing offset estimator for the nth hop targetcell can be defined by two methods

The first method comprises the following steps: setting a received signal power threshold. Specifically, when the ACF peak power of an LRS component is below a certain threshold, the LRS component does not participate in the targetcellT timing offset estimation. The received signal power threshold may be an absolute power value or a relative power value with the first LRS component received power as a reference. The mathematical expression is:

targetcell's timing offset estimator

Wherein mean represents the arithmetic mean, and the letters below mean represent that the correlation powers of M LRS components participating in the averaging operation are all greater than or equal to a specific valueAnd (4) threshold. Since the greater the path propagation delay, the greater the power attenuation of the received signal, resulting in a reduction in the associated power. Therefore, by setting the threshold, the path propagation delay tau of all the source base stations participating in the average operation can be ensured_SiAre small and can be ignored, i.e., τ_Si≈0。

The formula of TOA is substituted into the aboveIn the formula (II) to analyzeThe intrinsic principles of the formula are defined. It is known thatThen

I.e. timing deviation estimatorApproximately equal to targetcell's true timing offset_TMean value E of timing deviation from all source base stations of last hop_SiThe difference. To obtainThereafter, targetcell adjusts the local clockBiasing calibrated local clock timingE, being approximately equal to the mean value of the timing deviations of all source base stations of the last hop_SiI.e. that ${\mathrm{\δ}}_T^{\mathrm{correct}}\stackrel{\mathrm{\Δ}}{=}{\mathrm{\δ}}_T-{\widehat{\mathrm{\δ}}}_T=E\left\{{\mathrm{\δ}}_{\mathrm{Si}}\right\}.$

And the second method comprises the following steps: the received signal power is weighted. Specifically, when estimating the targetcellT timing offset, the received power P of the LRS component is used_iEstimate TOA for TOA_RXiAnd (4) weighting. Received power P_iThe larger the size of the tube is,the greater the weight of (c). A possible mathematical expression is

Targetcell timing offset

Where g (□) is some increasing function.

Since the greater the path propagation delay, the greater the power attenuation of the received signal, resulting in a reduction in the associated power. Therefore, by setting the threshold, the path propagation delay tau can be ensured_SiThe weighted contribution of the large source base station to the timing offset estimator of targetcell is relatively small, while the path propagation delay τ of the source base station with the relatively large weighted contribution_SiAre small and the resulting total path propagation delay effect can be neglected.

The formula of TOA is substituted into the aboveIn the formula (II) to analyzeThe intrinsic principles of the formula are defined. It is known thatThen

Then

$\begin{array}{c}E\left\{{\widehat{\mathrm{\δ}}}_T\right\}={\mathrm{\δ}}_T-\frac{\underset{i}{\mathrm{\Σ}}\left[g\left(P_i\right)E\right\{{\mathrm{\δ}}_{\mathrm{Si}}\left\}\right]}{\underset{i}{\mathrm{\Σ}}g\left(P_i\right)}-\frac{\underset{i}{\mathrm{\Σ}}\left[g\left(P_i\right)E\right\{{\mathrm{\τ}}_{\mathrm{Si}}\left\}\right]}{\underset{i}{\mathrm{\Σ}}g\left\{P_i\right\}}-\frac{\underset{i}{\mathrm{\Σ}}\left[g\left(P_i\right)E\right\{{\mathrm{\ϵ}}_{\mathrm{Si}}\left\}\right]}{\underset{i}{\mathrm{\Σ}}g\left(P_i\right)}\\ ={\mathrm{\δ}}_T-E\left\{{\mathrm{\δ}}_{\mathrm{Si}}\right\}-\frac{\underset{i}{\mathrm{\Σ}}\left[g\left(P_i\right)E\right\{{\mathrm{\τ}}_{\mathrm{Si}}\left\}\right]}{\underset{i}{\mathrm{\Σ}}g\left(P_i\right)}\end{array}$

Based on the assumption, the path propagation delay τ_SiWeighted contribution g (P) of large source base station to targetcell's timing offset estimator_i) Path propagation delay tau of source base station being relatively small and weighted contributing relatively large_SiAre all relatively small, therefore

Can finally obtainI.e. timing deviation estimatorApproximately equal to targetcell's true timing offset_TMean value E of timing deviation from all source base stations of last hop_SiThe difference. To obtainThereafter, targetcell adjusts the local clockBiasing calibrated local clock timingE, being approximately equal to the mean value of the timing deviations of all source base stations of the last hop_SiI.e. that

A second type deployment scenario is that only the path propagation delay from a 0 th-hop base station (such as a macro station) to a 1 st-hop base station (smallcell) is large and can not be ignored; and the path propagation delay of the first LRS component from the nth hop base station (n ≧ 1) to the (n + 1) th hop base station (smallcell) can be ignored.

In the application scenario, the timing offset of the 1 st hop base station and the timing offset of the nth hop (n ≧ 2) can be respectively estimated by different methods.

The method for estimating the timing offset of the 1 st hop base station is first described below. In this application scenario, only 10 th hop base station (e.g., macro station) in one cluster may be required by configuration, and the path propagation delay τ between the 1 st hop targetcell and the 0 th hop base station may be measured in advance by a class-based method_S1The TOA relationship is as follows:a targetcell timing offset estimator may be defined accordinglyDefined as propagation delay τ by path_S1Calibrated TOA, i.e.:timing offset of 0 th hop base station (e.g. macro station) is not set_S1Approximately 0, timing measurement error_S1Has an average value of 0, thenI.e., targetcell timing offset estimatorApproximately equal to the true timing offset.

And the timing deviation estimation method of the nth hop (n is more than or equal to 2) base station is the same as the first type deployment scene.

In a third deployment scenario, except that the path propagation delay from a 0-hop base station (such as a macro station) to a 1-hop base station (smallcell) is not negligible, the path propagation delay from an nth-hop base station (n ≧ 1) to a first LRS component of an n + 1-hop base station (smallcell) is also not negligible.

In this application scenario, the synchronization method from hop 0 to hop 1 may refer to the second type deployment scenario.

The following mainly describes a synchronization method from the nth hop base station (n ≧ 1) to the (n + 1) th hop base station (smallcell). When the path propagation delay of the first LRS component is not negligible, it needs to be calibrated (i.e., the path propagation delay of the first LRS component is added, which is equivalent to excluding the path propagation delay effect of the first LRS component from the targetcell timing offset estimate).

The processing steps are as follows:

step1, targetcell measures the path propagation delay with all adjacent base stations in advance by implementing a class method, and makes a mapping table of the path propagation delay and the base station pair, wherein the format of the mapping table can be < path propagation delay, fromcell ID, tocell >. This measurement can be done at the restart of the targetcell. All base stations in the whole cluster can be restarted in turn when the UE service is inactive in every day/late night every week, and the path propagation delay between every two is measured;

step 2: targetcell selects a synchronization source sourcecell. The specific selection method may refer to the existing 3GPP standard. Setting the stratumlevel of sourcecell as n-1, and setting the stratumlevel of targetcell as n;

step 3: and the targetcell acquires the offset of the LRS subframe sent by the sourcecell. targetcell further obtains the cellID set of the neighboring sourcecell with stratumlevel n-1. the targetcell can obtain the cell id information of the neighboring sourcecell through blind detection of PSS/SSS signals in Step2 or backhaul signaling (for example, through an X2/S1 interface). the targetcell searches a mapping table of the path propagation delay and the base station pair determined by Step1 according to the obtained cell ID set of the adjacent sourcecell<Delay of path propagation, fromcell ID, tocell ID>Obtaining shortest path tau of adjacent sourcecell from targetcell to stratumlevel n-1_min；

Step 4: in the same first category, in order to suppress the influence of the LRS component with a large path propagation delay on the targetcellT timing offset estimation, two technical approaches may be adopted:

setting a received signal power threshold and then defining

Targetcell timing offset

Received signal power weighting, i.e. defining ${\widehat{\mathrm{\&delta;}}}_T=\frac{\underset{i}{\mathrm{\&Sigma;}}[g\left(P_i\right)\&times;(-\mathrm{TO}{A}_{\mathrm{RXi}}+{\mathrm{\&tau;}}_{\min })]}{\underset{i}{\mathrm{\&Sigma;}}g\left(P_i\right)}$

Targetcell timing offset

Where g (□) is some increasing function. Other function definitions may refer to the first type of deployment scenario. Wherein, tau_minNot necessarily equal to the path propagation delay of the first LRS component, but generally better path propagation delay calibration and air interface synchronization performance can be obtained.

And transmitting the LRS signals scrambled by the cell in the same or different downlink subframes by a plurality of sourcecells in the same layer according to the requirement, and ensuring that the LRS signals from different sourcecells in the same layer are orthogonal to each other by a proper scheduling mechanism. In normal operation (without loss of synchronization), targetcell only listens to the LRS signal of one synchronization source at a time to maintain air interface synchronization.

The core idea of the method dB in the embodiment of the invention is that a stratumlevel is bound with an LRSubframe offset; this allows to completely suppress the interference between LRS signals of the same layer.

As shown in fig. 9 and 10, multiple sourcecells in the same layer transmit the cell-scrambled LRS in the same or different downlink subframes. The cell-scrambled LRS signal may be legacy RS (reference signal), such as CRS, PRS, CSI-RS, etc., or may be a newly designed reference signal.

To ensure that LRS signals from multiple sourcecells on the same layer are orthogonal to each other, RE (resource/resource element) resources corresponding to the LRS signals may be staggered in a subframe dimension and/or a frequency dimension within a subframe and/or an OFDM (orthogonal frequency division multiplexing) symbol dimension within a subframe. The offsets include both time domain offsets (subframe level offsets and symbol offsets-OFDM symbol offsets) and frequency domain offsets (i.e., frequency offsets/subcarrier offsets).

Specifically, different LRS signals have different frequency dimension multiplexing degrees (i.e., the LRS signals are staggered by subcarrier shifting in the frequency domain), for example, the frequency dimension multiplexing degree of a 2-port CRS is 3, and the frequency dimension multiplexing degree of a PRS is 6. When the number of source cells in the same layer is too large to orthogonally transmit the LRS signal in the same subframe, a new multiplexing dimension, i.e., a subframe offset dimension, may be introduced to ensure the orthogonality of the LRS signal, and a specific offset method is shown in fig. 9 and fig. 10.

The muting (listening) mechanism between different stratumlevels can ensure better synchronous interception performance. Fig. 9 and 10 show two different mutting mechanisms. Fig. 9(Opt1) shows that all mutes are across layers, that is, no matter which subframe on stratumlevel sends the LRS signal, all base stations of other stratumlevels are muted (do not send data) at the same subframe to avoid interfering with the LRS signal listening performance. Fig. 10(Opt2) shows neighbor-layer listening, i.e., when the nth layer base station transmits an LRS signal, the n +2 th layer is muted to avoid interfering with the LRS signal listening performance of the n +1 th layer.

Multiple base stations in the same layer coordinate their LRS transmission resources (including transmission subframes, subcarrier offsets and OFDM symbols within the transmission subframes) through interactive backhaul signaling to ensure that their RE resources corresponding to their LRS signals are staggered.

Several possible scheduling mechanisms are illustrated below to ensure that LRS signals from different sourcecells in the same layer are transmitted in a staggered manner on different time frequency resources.

Option 1: a centralized listeningrscatter (mode) scheduling mechanism is adopted: there is some central controller that centrally manages and guarantees the orthogonality of listengrs scatter of all eNB target base stations. Specifically, the central controller maintains an lrscatter database.

1. When a base station wants to determine where it is sending an LRS signal, it first sends a request signaling to the central controller requesting to feed back an LRSpattern that does not cause collision;

2. the central controller selects an LRSpattern which does not conflict with LRSpattern of all existing base stations according to the maintained LRSpattern database, and feeds back the information to the requesting base station through signaling;

3. the central controller adds the fed-back LRSpattern into an LRSpattern database to update and maintain the database;

4. requesting a base station to send an LRS signal according to LRSpattern fed back by a central controller;

5. the request and feedback signaling can be transmitted through backhaul (such as an S1 interface, an X2 interface);

6. the LRSpattern at least includes information such as LRS subframe offset and LRS signal repetition period.

Option 2: there are two implementation mechanisms for the distributed listeningPRattern scheduling mechanism.

Alt1 based on backhaul signaling. Each eNB consults LRS configuration information of adjacent or all base stations through backhaul signaling to determine the LRS configuration information of the eNB so as to ensure the LRS signal orthogonality with LRS signals of other eNBs, and the specific steps include:

1. when a base station wants to determine where to send an LRS signal, the base station firstly sends a request signaling to an adjacent base station to request the other side to feed back the LRSpattern used by the other side;

2. the adjacent base station sends the request and feeds back the LRSpattern used by the adjacent base station to the requesting base station;

3. the requesting base station maintains a local LRSpattern database according to all the collected LRSpattern information of the adjacent base stations, and then selects an LRSpattern which does not conflict with the LRSpattern of all the adjacent base stations according to the database;

4. requesting the base station to send the LRS signal according to the currently selected LRSpattern.

And Alt2, each eNB firstly monitors (blind detects) LRS signals of other eNBs through an air interface, and then configures the LRS configuration information of each eNB based on the monitoring result so as to ensure the LRS signals of the other eNBs to be orthogonal. The method comprises the following specific steps:

1. when a base station (called as a current base station) wants to determine where to transmit an LRS signal, the base station firstly determines a candidate subframe of the LRS signal to be transmitted, and then listens for LRS signals transmitted by other adjacent cells on the candidate subframe (blind detection);

2. in order to avoid the influence of the listening process on the UE traffic of the current base station, the current base station may configure a measurement interval (measurementgap). In particular, the measurement interval may be configured as an MBSFM (multicast/multicast single frequency network) subframe;

3. if the current base station finds that all available LRS configuration resources of the candidate subframe are occupied by LRS signals of other cells through blind detection, the current base station reselects a candidate subframe of an LRS signal to be transmitted, and then executes the step1 again;

4. otherwise, if the candidate subframe is not occupied by the LRS signals of other cells through blind detection, the current base station occupies the subframe and selects an unoccupied LRS configuration resource to send the LRS signals.

In addition, in order to avoid the hearing loss, the following constraint conditions need to be additionally met:

constraint 1: in the same cluster, the transmission periods of all listeningRS are the same;

constraint 2: if there is a smallcell with on/offset switching function, then ask that the offset also sends listeningRS;

constraint 3: the LRS needs to be distinguishable from non-LRS signals, e.g., the LRS signal is a newly designed reference signal and can be blindly detected by other neighboring cells.

And a method dC, wherein multiple sourcecells in the same layer send the LRS signals scrambled by the cell in different downlink subframes according to requirements, the LRS signals are only sent in special subframes of the TDD system, and the LRS signals from different sourcecells in the same layer are ensured to be orthogonal to each other through a scheduling mechanism the same as the method dB. The specific configuration of its LRS signal is seen in the scheme in patent application 201410035839.9, as follows:

an air interface synchronization scheme for transmitting an LRS signal by using a GP (guard interval) of a TDD (time division duplex) special subframe, as shown in fig. 11, a TDDsourcecell transmits an LRS signal in the GP of a special subframe. One possible embodiment is: the ratio of uplink and downlink time slots of the special subframe is 9: 3: 2, downlink DwPTS (downlink pilot time slot) occupies 9 OFDM symbols, GP occupies 3 OFDM symbols, and uplink UpPTS (uplink pilot time slot) occupies 2 OFDM symbols. Sourcecell transmits the LRS signal using the first OFDM symbol of the GP. The LRS signal may be a legacy RS (e.g., CRS, PRS, CSI-RS, etc.), and the term "clipping" refers to transmitting a legacy RS (reference signal) signal only on the LRS transmitting OFDM symbol and not transmitting data on any other OFDM symbol.

The scheme shown in fig. 11 skillfully utilizes the advantage that data is not transmitted on GP of TDD special subframe, and can automatically implement cross-layer total muting function. Therefore, the scheme has better synchronous interception performance.

On the other hand, the scheme is completely transparent to the UE and has ideal backward compatibility.

However, the scheme shown in fig. 11 has a certain system overhead, i.e. all base stations are required to reserve (vacate) several (≧ 1) OFDM symbols in GP for transmitting/listening to LRS signal, which may cause a certain resource overhead and waste. However, if the number of OFDM symbols occupied by the LRS signal is small (e.g., ═ 1), the traffic rate is hardly affected, because the traffic rate is determined by the TBS (transport block size), and the use or non-use of one OFDM symbol has little influence on the TBS, for example, the uplink and downlink slot allocation 9: 3: 2 (adopted in the solution of patent application 201410035839.9) and 10: 2: 2 (compare scheme, LRS of 1 OFDM symbol is released for traffic communication) generally has TBS of the system, so the traffic rates of both are the same. Of course, although both TBSs are the same, the transmission bit sizes of both are different, which affects the coding/decoding performance. The overhead of the solution in patent application 201410035839.9 can therefore be expressed as: the coding/decoding performance (reflected as robustness) is slightly degraded on the premise that the TBS (reflected as traffic rate) remains substantially unchanged.

The method dC enhances the scheme shown in FIG. 11 from the perspective of mapping stratumlevel and subframe offset for an smallcell ultra-dense deployment scenario.

As shown in fig. 12, by using a suitable scheduling mechanism, a synchronization level is associated with a certain LRS subframe offset set, so as to ensure that multiple sourcecells in the same layer transmit cell-scrambled LRS signals in different downlink subframes.

On the basis of the method dB, the combination scheme can automatically realize a cross-layer mutting mechanism, so that additional system overhead is not required to be introduced, and a further excellent effect is achieved.

In summary, when a future small cell more dense deployment scenario (e.g., 5GUDN: ultra dense network) is oriented, more than 60 small cells may be in a cluster, and more than 7 small cells may be in each hop (layer), if the existing RIBS technology is adopted, that is, the same-layer base station respectively sends LRS signals scrambled by respective cell ids on the same subframe, because the number of the same-layer sourcecells exceeds the reuse degree of the LRS signals, the LRS signals are difficult to completely stagger on RE resources even through cell planning, and therefore interfere with each other and reduce the network air interface synchronization performance.

The embodiment of the invention provides 3 types of RIBS parameter configuration schemes and embodiments aiming at the problem that LRS signals sent by a plurality of sourcecells on the same layer interfere with each other in air interface synchronous application under an smallcell ultra-dense deployment scene:

and (2) transmitting the completely same LRS signals in the same LRS transmission subframe by a plurality of sourcecells in the same layer, namely the LRS signals of the cells in the same layer have the same sequence and occupy the same RE resource.

And transmitting the LRS signals scrambled by the cell in the same or different downlink subframes by a plurality of sourcecells in the same layer according to the requirement, and ensuring that the LRS signals from different sourcecells in the same layer are orthogonal to each other by a proper scheduling mechanism.

Method dC, combine method dB with scheme in patent application 201410035839.9-RIBS scheme that sends LRS signal in GP of TDD special subframe-define a new synchronization level and LRS sends subframe offset (LRS subframe offset for short) -a new correspondence, namely through the appropriate scheduling mechanism, a synchronization level and certain LRS subframe offset set (LRSubframeoffset, and the number of offsets in the set is greater than or equal to 1) corresponds, to ensure that multiple sourcecells of the same layer send LRS signal scrambled in different downlink subframes.

The RIBS parameter configuration technology provided by the embodiment of the invention can solve the problem of mutual interference caused by RE resource conflict of synchronous reference signals sent by a plurality of sourcecells at the same layer in a small cell ultra-dense deployment scene, thereby effectively ensuring the inter-station air interface synchronization performance in the small cell ultra-dense deployment scene.

While the preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (22)

1. A method for configuring signal parameters in air interface synchronization is characterized by comprising the following steps:

configuring a reference signal serving as an LRS for a same-layer source base station, wherein the LRS of the same-layer source base station is the same;

configuring the same subframe offset for the LRS sent by the source base stations at the same layer, and configuring different subframe offsets for the LRS sent by the source base stations at different layers;

and controlling each source base station to send the LRS at the corresponding subframe position based on the subframe offset of the LRS configured by the source base station.

2. The method of claim 1, wherein the configuring the reference signal as the LRS for the same-layer source base station comprises:

any one of CRS, PRS and CSI-RS is configured as a reference signal of an LRS of a same-layer source base station, and the same initial phase is configured for the any one of the reference signals.

3. The method of claim 2, wherein said configuring the same initial phase for the arbitrary reference signal comprises:

the base station related parameters in the initial phase calculation formula are replaced with the radio frame number to generate the same initial phase.

4. A method for configuring signal parameters in air interface synchronization is characterized by comprising the following steps:

receiving the same LRS from a plurality of source base stations in the same layer;

acquiring the sending time of a source base station corresponding to each LRS from the LRSs, wherein the sending time of the source base station takes a source base station clock as a reference;

obtaining local receiving time corresponding to a plurality of LRSs when the LRSs arrive, wherein the local receiving time takes a local clock as a reference;

and calculating by using the sending time and the local receiving time of the source base station corresponding to the LRSs to obtain an average timing deviation estimated value.

5. The method of claim 4, wherein before calculating the mean TD estimate using the transmission time and the local receiving time of the source BS corresponding to each of the LRSs, the method further comprises:

obtaining path propagation delay time corresponding to each of the LRSs;

the calculating to obtain the average timing deviation value by using the source base station sending time and the local receiving time corresponding to the LRSs specifically includes:

and calculating by using the sending time, the local receiving time and the path propagation delay time of the source base station corresponding to the LRSs to obtain an average timing deviation value.

6. A method for configuring signal parameters in air interface synchronization is characterized by comprising the following steps:

configuring an LRS mode for a base station to ensure that the LRS sent by the base station is orthogonal to LRSs sent by other base stations in the same layer;

transmitting the cell-scrambled LRS according to the LRS mode.

7. The method of claim 6, wherein the LRS transmitted by the BS and the LRS transmitted by other BSs in the same layer are located in GP of different special subframes respectively in the TDD system.

8. The method of claim 6, wherein said configuring an LRS mode for the base station comprises:

sending a signaling for requesting feedback of the used LRS mode to an adjacent base station in the same layer;

receiving response information fed back by the adjacent base station according to the signaling;

and acquiring an LRS mode which is different from LRS modes of all adjacent base stations in a local LRS mode database according to the response information.

9. The method of claim 6, wherein said configuring an LRS mode for the base station comprises:

determining a candidate subframe of an LRS to be transmitted;

monitoring LRSs sent by other adjacent cells on the candidate subframes;

if the interception result is that the candidate subframe has LRS configuration resources which are not occupied by LRSs of other adjacent cells, determining an unoccupied LRS configuration resource;

and determining an LRS mode according to the determined LRS configuration resource.

10. The configuration method of claim 9, further comprising:

and if the interception result is that all the available LRS configuration resources of the candidate subframe are occupied by the LRSs of the other adjacent cells, continuing to execute the determination of the candidate subframe of the LRS to be sent.

11. The method of claim 9, wherein the transmission periods of all LRSs are the same within the same cluster; if the micro station has the switch conversion function, the LRS is also sent even if the micro station is in a dormant state; the LRS has a characteristic point different from other signals and can be identified by other neighboring cells.

12. An apparatus for configuring signal parameters in air interface synchronization, comprising:

a first configuration module, configured to configure a reference signal as an LRS for a same-layer source base station, where the LRSs of the same-layer source base station are the same;

a second configuration module, configured to configure the same subframe offset for the LRS sent by the source base stations on the same layer, and configure different subframe offsets for the LRS sent by the source base stations on different layers;

and the control module is used for controlling each source base station to send the LRS at the corresponding subframe position based on the subframe offset of the LRS configured by the source base station.

13. The configuration apparatus of claim 12, wherein the first configuration module comprises:

a first configuration unit, configured to configure any one of a CRS, a PRS, and a CSI-RS as a reference signal of an LRS of a peer source base station;

and the second configuration unit is used for configuring the same initial phase for the arbitrary reference signal.

14. The configuration apparatus according to claim 13, wherein the second configuration unit comprises:

a replacing component for replacing the base station related parameter in the initial phase calculation formula with the radio frame number to generate the same initial phase.

15. An apparatus for configuring signal parameters in air interface synchronization, comprising:

a receiving module, configured to receive the same LRS from multiple source base stations on the same layer;

a first obtaining module, configured to obtain, from the LRSs, source base station sending time corresponding to each LRS, where the source base station sending time is based on a source base station clock;

a second obtaining module, configured to obtain local receiving times corresponding to arrival of the LRSs, where the local receiving times are based on a local clock;

and the operation module is used for performing operation by utilizing the source base station sending time and the local receiving time corresponding to the LRSs to obtain an average timing deviation estimated value.

16. The configuration device of claim 15, further comprising:

a third obtaining module, configured to obtain path propagation delay time corresponding to each of the LRSs before the operation module performs the operation;

the operation module is specifically configured to:

and calculating by using the sending time, the local receiving time and the path propagation delay time of the source base station corresponding to the LRSs to obtain an average timing deviation value.

17. An apparatus for configuring signal parameters in air interface synchronization, comprising:

a third configuration module, configured to configure an LRS mode for the base station, so that the LRS sent by the base station is orthogonal to LRSs sent by other base stations in the same layer;

a sending module, configured to send the cell-scrambled LRS according to the LRS mode.

18. The apparatus of claim 17, wherein the LRS transmitted by the bs and LRSs transmitted by other bss in the same layer are located in GP of different special subframes in the TDD system, respectively.

19. The configuration apparatus of claim 17, wherein the third configuration module comprises:

a first sending unit, configured to send a signaling requesting feedback of an LRS mode used to a neighboring base station in the same layer;

a receiving unit, configured to receive response information fed back by the neighboring base station according to the signaling;

and the obtaining unit is used for obtaining an LRS mode which is different from LRS modes of all adjacent base stations in the local LRS mode database according to the response information.

20. The configuration apparatus of claim 17, wherein the third configuration module comprises:

a first determining unit, configured to determine a candidate subframe of an LRS to be transmitted;

a second sending unit, configured to listen to LRSs sent by other neighboring cells on the candidate subframe;

a second determining unit, configured to determine an unoccupied LRS configuration resource if the listening result indicates that the LRS configuration resource unoccupied by the LRS of the other neighboring cell exists in the candidate subframe;

a third determining unit, configured to determine an LRS mode according to the determined LRS configuration resource.

21. The configuration device of claim 20, further comprising:

and a circulating module, configured to continue to determine a candidate subframe of an LRS to be transmitted if the listening result indicates that all available LRS configuration resources of the candidate subframe are occupied by LRSs of other neighboring cells.

22. The apparatus of claim 20, wherein the transmission periods of all LRSs are the same within the same cluster; if the micro station has the switch conversion function, the LRS is also sent even if the micro station is in a dormant state; the LRS has a characteristic point different from other signals and can be identified by other neighboring cells.