Patent Description:
As wireless communication technologies are increasingly widely used, a multi-antenna technology has become one of key technologies for wireless transmission. When a signal is transmitted in a radio frequency channel, an amplitude and a phase of the signal change due to a nonlinear feature of the channel. Therefore, an antenna calibration function is designed. Multi-channel antenna calibration is intended to obtain amplitude and phase features of the radio frequency channel, to compensate for an amplitude and a phase of the radio frequency channel, so as to ensure amplitude consistency and phase consistency between transmitter channels as well as between receiver channels, and amplitude reciprocity and phase reciprocity between receiver channels and transmitter channels.

A position of a conventional antenna calibration coupling port is located between an antenna filter and the antenna, that is, located in an antenna feeder unit. An antenna calibration circuit is located in a radio frequency unit at which a radio frequency link is located. In this case, the antenna calibration circuit needs to be connected to the antenna feeder unit to receive or obtain a signal, and then connected to the radio frequency unit to process the signal. A link of the antenna calibration circuit needs to span the foregoing antenna feeder unit and the radio frequency unit, and one or more cables (or connectors) and a combiner unit need to be added. Consequently, there are more components required, an assembly technique is complex, and implementation costs are relatively high.

<CIT> discloses a multiple-input multiple-output (MIMO) antenna having a lightweight stacked structure, wherein the structure comprises a plurality of antenna elements, a plurality of band-pass filters connected to the plurality of antenna elements, a plurality of transmitting and receiving circuits connected to the plurality of band-pass filters and calibration network with a plurality of switches in a tree structure. The calibration network coupled to branches between the plurality of transmitting and receiving circuits and the plurality of band-pass filters. The calibration may be performed for each of transmission paths after an RF deviation of a plurality of band-pass filters and antenna feeder lines measured in advance is included as an offset value in a deviation between.

The object of the present invention is to provide a base station and an antenna calibration method, to simplify an assembly technique of the antenna calibration apparatus, and help reduce implementation costs of the antenna calibration apparatus. This object is solved by the attached independent claims and further embodiments and improvements of the invention are listed in the attached dependent claims. Hereinafter, up to the "brief description of the drawings", expressions like ". aspect according to the invention", "according to the invention", or "the present invention", relate to technical teaching of the broadest embodiment as claimed with the independent claims. Expressions like "implementation", "design", "optionally", "preferably", "scenario", "aspect" or similar relate to further embodiments as claimed, and expressions like "example", ". aspect according to an example", "the disclosure describes", or "the disclosure" describe technical teaching which relates to the understanding of the invention or its embodiments, which, however, is not claimed as such.

According to a first aspect in accordance with the invention, the invention provides a a base station according to claim <NUM>.

According to the base station according to the invention, a position of an antenna calibration coupling port is arranged between the antenna filter and the radio frequency link. This enables the calibration circuit to directly send or receive a calibration signal through a radio frequency unit to perform antenna calibration, without adding components such as a cable, a connector, and a combiner unit. This simplifies an assembly technique of the antenna calibration apparatus, and helps reduce implementation costs of the antenna calibration apparatus.

It should be understood that the antenna may also be referred to as an antenna element, a feeder antenna, or another name; an antenna channel may also be referred to as a channel or another name; and the calibration circuit may also be referred to as an antenna calibration circuit or another name. This is not limited in this embodiment of this application.

It should be further understood that the antenna and the antenna filter belong to an antenna feeder unit, and the radio frequency link and the calibration circuit belong to the radio frequency unit. The antenna calibration coupling port is a connection port of the calibration circuit, and may also be referred to as an antenna calibration port or another name. In this embodiment of this application, a position of the antenna calibration coupling port of each antenna is between the antenna filter and the radio frequency link. In this way, the calibration circuit may send or receive the first calibration signal through the antenna calibration coupling port. In other words, the calibration circuit may send or receive the first calibration signal through the position between the antenna filter and the radio frequency link connected to the second end of the antenna filter. The first calibration signal is a calibration signal generated in a running process of a live network.

It should be understood that, because the position of the antenna calibration coupling port is between the antenna filter and the radio frequency link, a signal sent or received by the calibration circuit may not pass through the antenna filter. An error (which may include, for example, a PCB cable error, a connector error, an antenna filter error, an antenna network error, or an antenna element error) of a link between the antenna and the antenna filter needs to be obtained through making a table in an equipment (equipment tabling). In other words, the equipment tabling is intended to compensate for inconsistency of hardware links. In a production process of the apparatus, signal measurement is performed, and an obtained compensation parameter is stored in a memory (for example, a memory) for subsequent calibration. In this embodiment of this application, the compensation parameter in the equipment tabling process is referred to as the first compensation parameter. However, it should be understood that the first compensation parameter may also be referred to as an equipment tabling compensation parameter or another name. This is not limited in this embodiment of this application. Once the apparatus is delivered, the first compensation parameter is already stored. In a possible implementation, the first compensation parameter is stored in the memory in a form of a table (for example, an equipment table). However, this is not limited in this embodiment of this application.

In an actual running process of the live network, the calibration circuit may obtain the first compensation parameter of each antenna from the memory, determine the second compensation parameter of each antenna based on the first compensation parameter and the first calibration signal obtained from the antenna calibration coupling port, and further calibrate the antenna by using the second compensation parameter. The second compensation parameter is a compensation parameter in the actual running process of the live network. The second compensation parameter may also be referred to as a calibration compensation parameter or another name. This is not limited in this embodiment of this application.

The second calibration signal is a calibration signal generated in the equipment tabling process. In the equipment tabling process, one or more equipment tabling antennas are required, which are also referred to as antennas used for testing in this specification. It should be understood that if there is only one equipment tabling antenna, a position of the equipment tabling antenna may be adjusted each time to sweep each antenna in the l antennas. In addition, one antenna needs to be selected from the l antennas as the reference antenna, to calculate an error between the reference antenna and another antenna. In this embodiment of this application, the ith antenna is the reference antenna.

With reference to the first aspect, in some implementations of the first aspect, the first calibration signal includes ej and fj, ej represents a calibration signal received by the calibration circuit and sent by a transmitter module corresponding to the jth antenna, and fj represents a calibration signal received by a receiver module corresponding to the jth antenna and sent by the calibration circuit; a second compensation parameter of the jth antenna includes a second compensation parameter τTj of a transmitter link corresponding to the jth antenna and a second compensation parameter τRj of a receiver link corresponding to the jth antenna; the ith antenna in the l antennas is used as the reference antenna, and the second compensation parameter τTj of the transmitter link corresponding to the jth antenna in the l antennas meets: <MAT>; and
the second compensation parameter τRj of the receiver link corresponding to the jth antenna in the l antennas meets: <MAT>.

In the actual running process of the live network, a receiver channel and a transmitter channel of the antenna need to be calibrated separately. Therefore, the first calibration signal may include the calibration signal ej corresponding to the transmitter link and the calibration signal fj corresponding to the receiver link. Correspondingly, the second compensation parameter may include the compensation parameter τTj corresponding to the transmitter link and the compensation parameter τRj corresponding to the receiver link. The second compensation parameter may be obtained through calculation based on the first compensation parameter and the first calibration signal.

With reference to the first aspect, in some implementations of the first aspect, the l antennas correspond to a first frequency band, and the antenna calibration apparatus further includes: k antennas, corresponding to a second frequency band, where k is an integer greater than or equal to <NUM>; k antenna filters, where first ends of the k antenna filters are respectively connected to the k antennas; and k radio frequency links, respectively connected to second ends of the k antenna filters. The calibration circuit is connected to each of the second ends of the k antenna filters, and is configured to: send or receive a third calibration signal through a position between each antenna filter in the k antenna filters and a radio frequency link connected to the second end of each antenna filter in the k antenna filters, and calibrate each antenna in the k antennas based on the third calibration signal.

Similar to the first frequency band corresponding to the l antennas, in the case of the second frequency band, a position of an antenna calibration coupling port of each antenna in the k antennas is between the antenna filter and the radio frequency link. In this way, the calibration circuit may send or receive the third calibration signal through the antenna calibration coupling port. In other words, the calibration circuit <NUM> may send or receive the third calibration signal through the position between the antenna filter and the radio frequency link connected to the second end of the antenna filter. The third calibration signal is a calibration signal generated in the running process of the live network. For related descriptions of the k antennas in the second frequency band, refer to the descriptions of the l antennas in the first frequency band.

With reference to the first aspect, in some implementations of the first aspect, the calibration circuit is specifically configured to: determine a first compensation parameter of each antenna in the k antennas; determine a second compensation parameter of each antenna in the k antennas based on the first compensation parameter of each antenna in the k antennas and the third calibration signal; and calibrate each antenna in the k antennas based on the second compensation parameter of each antenna in the k antennas.

Similar to the first frequency band corresponding to the l antennas, in the second frequency band, equipment tabling also needs to be performed to obtain the first compensation parameter, and the first compensation parameter is written into the memory for subsequent calibration. In the second frequency band, an equipment tabling and calibration process of the k antennas is similar to the equipment tabling and calibration process in the first frequency band.

According to the base station according to the first aspect of the invention, the assembly technique of the antenna calibration apparatus is simplified and the implementation costs of the antenna calibration apparatus are reduced. In addition, antenna calibration of a multi-band and multi-antenna channel can be implemented, and development costs are further reduced.

It should be understood that, in the equipment tabling and calibration process, the reference antenna needs to be selected. Reference antennas in frequency bands are different herein. To be specific, in the first frequency band, the reference antenna needs to be selected from the l antennas corresponding to the first frequency band; in the second frequency band, the reference antenna needs to be selected from the k antennas corresponding to the second frequency band.

It should be further understood that a sequence of calibration processes of antennas in each of the frequency bands is not limited in this application. The calibration circuit may calibrate one antenna once obtaining a second compensation parameter corresponding to the antenna. Alternatively, after obtaining the second compensation parameters corresponding to all the antennas, the calibration circuit calibrates all the antennas together. This is not limited in this embodiment of this application.

According to a second aspect according to the invention, the invention provides an antenna calibration method according to claim <NUM>.

In embodiments shown below, "first", "second", "third" and various numbers are merely used for distinguishing for ease of description, and are not used to limit the scope of the embodiments of this application. For example, different signals and different parameters are distinguished. In addition, "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system and product that include a series of steps or units, or other steps or units inherent to a device.

It should be understood that the technical solutions in the embodiments of this application may be applied to various communications systems, for example, a long term evolution (long term evolution, LTE) system, an LTE frequency division duplex (frequency division duplex, FDD) system, an LTE time division duplex (time division duplex, TDD) system, a universal mobile telecommunications system (universal mobile telecommunications system, UMTS), a worldwide interoperability for microwave access (worldwide interoperability for microwave access, WiMAX) communications system, a 5th generation (5th generation, <NUM>) system, a new radio (new radio, NR) system, or another evolved communications system.

<FIG> is a schematic block diagram of an antenna calibration apparatus <NUM> according to an embodiment of this application. As shown in <FIG>, the antenna calibration apparatus <NUM> includes: l antennas <NUM>, l antenna filters <NUM>, l radio frequency links <NUM>, and a calibration circuit <NUM>, where l is an integer greater than or equal to <NUM>.

As shown in <FIG>, the l antennas <NUM> are respectively an antenna <NUM>, an antenna <NUM>,. , and an antenna l. The l antennas <NUM> are respectively connected to the l antenna filters <NUM> (which are respectively an antenna filter <NUM>, an antenna filter <NUM>,. , and an antenna filter l, and are not marked in the figure) and the l radio frequency links <NUM> (which are respectively a radio frequency link <NUM>, a radio frequency link <NUM>,. , and a radio frequency link l, and are not marked in the figure), thereby forming l antenna channels. Further, the l radio frequency links <NUM> may include l radio frequency transmitter links <NUM> and l radio frequency receiver links <NUM>, which respectively form l antenna transmitter channels and l antenna receiver channels with the l antennas and the l antenna filters.

In <FIG>, the l antennas <NUM> are respectively connected to first ends of the l antenna filters <NUM>, and the l radio frequency links <NUM> are respectively connected to second ends of the l antenna filters <NUM>. Each of the second ends of the l antenna filters is connected to the calibration circuit <NUM>. The antenna <NUM> is used as an example. The antenna <NUM> is connected to a first end of the antenna filter <NUM>, a second end of the antenna filter <NUM> is connected to the radio frequency link <NUM>, and the second end of the antenna filter <NUM> is further connected to the calibration circuit <NUM>. Each of the second ends of the l antenna filters is connected to the calibration circuit <NUM>.

It should be understood that the antenna may also be referred to as an antenna element, a feeder antenna, or another name; the antenna channel may also be referred to as a channel or another name; and the calibration circuit may also be referred to as an antenna calibration circuit or another name. This is not limited in this embodiment of this application.

It should be further understood that the antenna and the antenna filter belong to an antenna feeder unit, and the radio frequency link and the calibration circuit belong to a radio frequency unit. The antenna calibration coupling port is a connection port of the calibration circuit, and may also be referred to as an antenna calibration port or another name. In this embodiment of this application, as shown in <FIG>, a position of the antenna calibration coupling port of each antenna is between the antenna filter and the radio frequency link. In this way, the calibration circuit <NUM> may send or receive a first calibration signal through the antenna calibration coupling port. In other words, the calibration circuit <NUM> may send or receive the first calibration signal through the position between the antenna filter and the radio frequency link connected to the second end of the antenna filter. The first calibration signal is a calibration signal generated in a running process of a live network.

According to the antenna calibration apparatus in this embodiment of this application, the position of the antenna calibration coupling port is arranged between the antenna filter and the radio frequency link. This enables the calibration circuit to directly send or receive a calibration signal through the radio frequency unit to perform antenna calibration, without adding components such as a cable, a connector, and a combiner unit. This simplifies an assembly technique of the antenna calibration apparatus, and helps reduce implementation costs of the antenna calibration apparatus.

For example, the calibration circuit may be specifically a printed circuit board (printed circuit board, PCB), or may include another component, or may be integrated into a chip system. It should be understood that the calibration circuit may include an input circuit or interface configured to send a signal, and an output circuit or interface configured to receive a signal. Further, the calibration circuit may further include a memory and a processor, where the memory may store the signal obtained by the calibration circuit and a corresponding processing program, and the processor may perform calibration processing based on the processing program stored in the memory. Optionally, there may be one or more processors, and one or more memories. Optionally, the memory and the processor may be integrated together, or may be separately disposed. This is not limited in this embodiment of this application.

In addition, the antenna calibration apparatus may be any multi-antenna apparatus that can implement the foregoing functions. This is not limited in this embodiment of this application. In a possible implementation, the antenna calibration apparatus is a base station, for example, an evolved NodeB (evolved NodeB, eNB, or eNodeB) or a home base station (for example, home evolved NodeB, or home NodeB, HNB) in an LTE system, or gNB in a new radio (new radio, NR) system.

In an optional embodiment, the calibration circuit is specifically configured to: determine a first compensation parameter of each antenna in the l antennas; determine a second compensation parameter of each antenna based on the first compensation parameter and the first calibration signal; and
calibrate each antenna based on the second compensation parameter.

It should be understood that, because the position of the antenna calibration coupling port is between the antenna filter and the radio frequency link, a signal sent or received by the calibration circuit may not pass through the antenna filter. An error (which may include, for example, a PCB cable error, a connector error, an antenna filter error, an antenna network error, or an antenna element error) of a link between the antenna and the antenna filter needs to be obtained through equipment tabling. In other words, the equipment tabling is intended to compensate for inconsistency of hardware links. In a production process of the apparatus, signal measurement is performed, and an obtained compensation parameter is stored in a memory (for example, a memory) for subsequent calibration. In this embodiment of this application, the compensation parameter in the equipment tabling process is referred to as the first compensation parameter. However, it should be understood that the first compensation parameter may also be referred to as an equipment tabling compensation parameter or another name. This is not limited in this embodiment of this application. Once the apparatus is delivered, the first compensation parameter is already stored. In a possible implementation, the first compensation parameter is stored in the memory in a form of a table (for example, an equipment table). However, this is not limited in this embodiment of this application.

According to the antenna calibration apparatus shown in <FIG>, in an actual running process of the live network, the calibration circuit may obtain the first compensation parameter of each antenna from the memory, determine the second compensation parameter of each antenna based on the first compensation parameter and the first calibration signal obtained from the antenna calibration coupling port, and further calibrate the antenna by using the second compensation parameter. The second compensation parameter is a compensation parameter in the actual running process of the live network. The second compensation parameter may also be referred to as a calibration compensation parameter or another name. This is not limited in this embodiment of this application.

In an optional embodiment, the ith antenna in the l antennas is used as a reference antenna, and a first compensation parameter δj of the jth antenna in the l antennas meets: <MAT>.

A radio frequency link corresponding to the jth antenna includes a receiver link and a transmitter link, the receiver link is connected to a receiver module, the transmitter link is connected to a transmitter module, the jth antenna is connected to an antenna used for testing, aj represents a second calibration signal received by the receiver module and sent by the antenna used for testing, bj represents a second calibration signal received by the receiver module and sent by the calibration circuit, cj represents a second calibration signal received by the antenna used for testing and sent by the transmitter module, dj represents a second calibration signal received by the calibration circuit and sent by the transmitter module, i is an integer and <NUM>≤i≤l, and j is an integer ranging from <NUM> to l.

In this embodiment of this application, it is assumed that aj =hjCjRj, bj =DjRj, cj =TjCjhj, and dj = TjDj. hj represents a coupling degree (also referred to as a coupling loss) between the jth antenna and the equipment tabling antenna. Cj represents a system transmission function (which may include a PCB cable error, a connector error, an antenna filter error, an antenna network error, or an antenna element error existing after the transmitter link and the receiver link are combined) of a common part of the jth antenna. Rj represents a transmission function of the receiver link corresponding to the jth antenna. Tj represents a transmission function of the transmitter link corresponding to the jth antenna. Dj represents a transmission function of a link between the jth antenna and the calibration circuit.

It should be understood that, <MAT> is equal to <MAT>. "×" is omitted in the following embodiments for simplified description.

It should be further understood that, <MAT> does not mean absolute equation but equation satisfying a quantization range. "=" in this specification all refers to equation satisfying a quantization range. Details are not described again subsequently.

<FIG> shows an antenna calibration apparatus in an equipment tabling process. For example, an antenna <NUM> (that is, the first antenna) is a reference antenna. First, an equipment tabling antenna <NUM> performs sweeping to align with the antenna <NUM>, and the following steps are performed:.

The equipment tabling antenna <NUM> sends a second calibration signal, and a receiver module receives the second calibration signal and obtains a measurement result <MAT>.

A calibration circuit sends a second calibration signal through an antenna calibration coupling port, and the receiver module receives the second calibration signal and obtains a measurement result <MAT>.

A transmitter module sends a second calibration signal, and the equipment tabling antenna <NUM> receives the second calibration signal and obtains a measurement result <MAT>.

The transmitter module sends a second calibration signal, and the calibration circuit receives the second calibration signal through the antenna calibration coupling port and obtains a measurement result <MAT>.

Then, the equipment tabling antenna <NUM> performs sweeping to align with an antenna <NUM>, and steps similar to the foregoing steps are performed to obtain measurement results <MAT> <MAT> <MAT> and <MAT><MAT> may be obtained according to the foregoing formulas (<NUM>) and (<NUM>). <MAT> may be obtained according to the foregoing formulas (<NUM>) and (<NUM>). <MAT> may be obtained according to the foregoing formulas (<NUM>) and (<NUM>). <MAT> may be obtained according to the foregoing formulas (<NUM>) and (<NUM>).

Further, <MAT> may be obtained according to the formulas (<NUM>) and (<NUM>). <MAT> may be obtained according to the formulas (<NUM>) and (<NUM>).

Therefore, according to the formulas (<NUM>) and (<NUM>), <MAT> may be obtained, which represents a first compensation parameter of the antenna <NUM> relative to the antenna <NUM>. In this embodiment, it is assumed that coupling degrees between the equipment tabling antenna and the antennas are equal, that is, h<NUM> = h<NUM>.

By analogy, a first compensation parameter of each antenna relative to the antenna <NUM> in l antennas is calculated as follows: <MAT> In this way, l first compensation parameters respectively corresponding to the l antennas are obtained, and are stored in a memory, for example, written into an equipment table.

It should be understood that an example in which the antenna <NUM> is used as the reference antenna is merely used above for description. In actual application, the reference antenna may be any one of the l antennas. In addition, only one equipment tabling antenna is used as an example in <FIG> to describe a process of successively performing equipment tabling on each of the l antennas. In another possible implementation, there may be more equipment tabling antennas. For example, there are l equipment tabling antennas. In this way, equipment tabling can be concurrently performed for all or some antennas in the l antennas, helping improve efficiency of equipment tabling.

In an optional embodiment, the first calibration signal includes ej and fj. ej represents a calibration signal received by the calibration circuit and sent by a transmitter module corresponding to the jth antenna, and fj represents a calibration signal received by a receiver module corresponding to the jth antenna and sent by the calibration circuit. A second compensation parameter of the jth antenna includes a second compensation parameter τTj of a transmitter link corresponding to the jth antenna and a second compensation parameter τRj of a receiver link corresponding to the jth antenna. The ith antenna in the l antennas is used as the reference antenna, and the second compensation parameter τTj of the transmitter link corresponding to the jth antenna in the l antennas meets: <MAT>; and
the second compensation parameter τRj of the receiver link corresponding to the jth antenna in the l antennas meets: <MAT>.

In an actual running process of a live network, a receiver channel and a transmitter channel of the antenna need to be calibrated separately. Therefore, the first calibration signal may include the calibration signal ej corresponding to the transmitter link and the calibration signal fj corresponding to the receiver link. Correspondingly, the second compensation parameter may include the compensation parameter τTj corresponding to the transmitter link and the compensation parameter τRj corresponding to the receiver link. The second compensation parameter may be obtained through calculation based on the first compensation parameter and the first calibration signal.

In this embodiment of this application, it is assumed that <MAT>, and <MAT>, where <MAT> represents a transmission function of the receiver link corresponding to the jth antenna during actual running, <MAT> represents a transmission function of the transmitter link corresponding to the jth antenna during actual running, and <MAT> represents a transmission function of a link between the jth antenna and the calibration circuit during actual running.

In an optional embodiment, the calibration circuit is configured to: obtain the first calibration signal ej and fj corresponding to each antenna; determine, based on the first compensation parameter δj of each antenna and the first calibration signal ej corresponding to each antenna, a second compensation parameter τTj of a transmitter link corresponding to each antenna; determine, based on the first compensation parameter δj of each antenna and the first calibration signal fj corresponding to each antenna, a second compensation parameter τRj of a receiver link corresponding to each antenna; and compensate for the transmitter link corresponding to each antenna with the second compensation parameter τTj of the transmitter link corresponding to each antenna, and compensate for the receiver link corresponding to each antenna with the second compensation parameter τRj of the receiver link corresponding to each antenna.

Refer to the example in which the antenna <NUM> (that is, the first antenna) is the reference antenna, as shown in <FIG>. The following steps are performed to obtain the second compensation parameter corresponding to the transmitter link:
The transmitter module sends the first calibration signal, and the calibration circuit receives the first calibration signal through the antenna calibration coupling port and obtains measurement results <MAT> and <MAT><MAT> may be obtained according to the foregoing formulas (<NUM>) and (<NUM>).

A result of the first compensation parameter is multiplied by the foregoing formula (<NUM>), to obtain <MAT> which represents a second compensation parameter that is corresponding to the transmitter link and that is of the jth antenna relative to the antenna <NUM>. In this embodiment, it is assumed that <MAT>, and <MAT>.

Similarly, the following steps are performed to obtain a second compensation parameter corresponding to the receiver link:
The calibration circuit sends the first calibration signal through the antenna calibration coupling port, and the receiver module receives the first calibration signal and obtains measurement results <MAT> and <MAT><MAT> may be obtained according to the foregoing formulas (<NUM>) and (<NUM>).

A result of the first compensation parameter is multiplied by the foregoing formula (<NUM>), to obtain <MAT> which represents a second compensation parameter that is corresponding to the receiver link and that is of the jth antenna relative to the antenna <NUM>. In this embodiment, it is assumed that <MAT>, and <MAT>.

Finally, the corresponding receiver link and transmitter link are respectively supplemented with the result of the formula (<NUM>) and the result of the formula (<NUM>), to complete antenna calibration.

It should be understood that the calibration of the receiver link and the calibration of the transmitter link are two independent calibration processes, and may be performed in sequence, or may be processed in parallel. This is not limited in this embodiment of this application.

In addition, the following condition <NUM> may be obtained according to the formulas (<NUM>) and (<NUM>): <MAT> <MAT>.

The following condition <NUM> may be obtained by dividing (<NUM>) by (<NUM>): <MAT>.

An error of equipment tabling (which may also be referred to as precision of equipment tabling) affects a value of δj, which affects the condition <NUM> only and is unrelated to the condition <NUM>. A calibration algorithm affects a value of σj, which affects both the condition <NUM> and the condition <NUM>. In conclusion, the error of equipment tabling affects only forming precision of an open-loop beam, and has no impact on uplink and downlink reciprocity. Because impact of forming precision of the open-loop beam on a multi-antenna system is relatively weak, the antenna calibration apparatus in this embodiment of this application has a low requirement on precision of equipment tabling, which is likely to be met.

In the foregoing embodiment, frequency bands of the l antennas are the same, and all correspond to a first frequency band. This application does not exclude a case in which the antenna calibration apparatus further includes another frequency band. In other words, the antenna calibration apparatus is a multi-band multi-antenna channel.

In an optional embodiment, the l antennas correspond to the first frequency band, and the antenna calibration apparatus further includes: k antennas, corresponding to a second frequency band, where k is an integer greater than or equal to <NUM>; k antenna filters, where first ends of the k antenna filters are respectively connected to the k antennas; and k radio frequency links, respectively connected to second ends of the k antenna filters. The calibration circuit is connected to each of the second ends of the k antenna filters, and is configured to: send or receive a third calibration signal through a position between each antenna filter in the k antenna filters and a radio frequency link connected to the second end of each antenna filter in the k antenna filters, and calibrate each antenna in the k antennas based on the third calibration signal.

The antenna calibration apparatus further includes the k antennas corresponding to the second frequency band. Similar to the first frequency band, in the case of the second frequency band, the k antennas are connected to the k antenna filters and the k radio frequency links, to form k antenna channels. Further, the k radio frequency links may include k radio frequency transmitter links and k radio frequency receiver links, which respectively form k antenna transmitter channels and k antenna receiver channels with the k antennas and k antenna filters. The k antennas are respectively connected to first ends of the k antenna filters, and the k radio frequency links are respectively connected to second ends of the k antenna filters. Each of the second ends of the k antenna filters is further connected to the calibration circuit.

In an optional embodiment, the calibration circuit is specifically configured to: determine a first compensation parameter of each antenna in the k antennas; determine a second compensation parameter of each antenna in the k antennas based on the first compensation parameter of each antenna in the k antennas and the third calibration signal; and calibrate each antenna in the k antennas based on the second compensation parameter of each antenna in the k antennas.

According to the antenna calibration apparatus in this embodiment of this application, an assembly technique of the antenna calibration apparatus is simplified and implementation costs of the antenna calibration apparatus are reduced. In addition, antenna calibration of a multi-band and multi-antenna channel can be implemented, and development costs are further reduced.

In an optional embodiment, a reference antenna used to determine the first compensation parameter of each antenna in the k antennas is the qth antenna in the k antennas, q is an integer, and <NUM> ≤ q ≤ k.

<FIG> is a schematic diagram of a structure of another antenna calibration apparatus in an equipment tabling process. The antenna calibration apparatus shown in <FIG> includes N frequency bands, and N is an integer greater than or equal to <NUM>. The N frequency bands may include a same or different quantity of antennas. This is not limited in this embodiment of this application. A frequency band <NUM> corresponds to the foregoing first frequency band and includes l antennas. A frequency band <NUM> corresponds to the foregoing second frequency band and includes k antennas. In addition, the frequency band N includes m antennas, and m is an integer greater than or equal to <NUM>.

In the example in <FIG>, a reference antenna of the frequency band <NUM> is an antenna <NUM>. According to the corresponding descriptions of <FIG>, formulas (<NUM>) and (<NUM>), that is, a second compensation parameter, may be obtained. For example, a reference antenna of the frequency band <NUM> may be an antenna l+<NUM>, and a reference antenna of the frequency band N may be an antenna l+k+<NUM>. Like the frequency band <NUM>, in the case of the second frequency band, a second compensation parameter corresponding to each frequency band may be obtained. Then, a corresponding receiver link and a corresponding transmitter link are compensated for with the second compensation parameter corresponding to each frequency band, so as to complete antenna calibration.

It should be understood that <FIG> shows only one equipment tabling antenna. A position of the equipment tabling antenna may be adjusted each time to sweep each antenna in l+k+m antennas. In another possible implementation, one or more equipment tabling antennas may be separately disposed for each frequency band, so that equipment tabling processes of all frequency bands can be performed in parallel. This helps improve efficiency of equipment tabling.

The foregoing describes in detail the antenna calibration apparatus in the embodiments of this application with reference to <FIG>. The following describes in detail an antenna calibration method in the embodiments of this application with reference to <FIG>.

<FIG> is a schematic flowchart of an antenna calibration method <NUM> according to this application. The method <NUM> is applied to an antenna calibration apparatus including l antennas. The l antennas are respectively connected to first ends of l antenna filters, and second ends of the l antenna filters are respectively connected to l radio frequency links and each connected to a calibration circuit. The method <NUM> includes the following steps:.

S410: Obtain a first calibration signal, where the first calibration signal is sent or received by the calibration circuit through a position between each antenna filter in the l antenna filters and a radio frequency link connected to the second end of each antenna filter.

S420: Determine a first compensation parameter of each antenna in the l antennas.

S430: Determine a second compensation parameter of each antenna based on the first compensation parameter and the first calibration signal.

S440: Calibrate each antenna based on the second compensation parameter.

According to the antenna calibration method in this embodiment of this application, the position of the antenna calibration coupling port is arranged between the antenna filter and the radio frequency link. This enables the calibration circuit to directly send or receive a calibration signal through a radio frequency unit to perform antenna calibration, without adding components such as a cable, a connector, and a combiner unit. This simplifies an assembly technique of the antenna calibration apparatus, and helps reduce implementation costs of the antenna calibration apparatus.

The method <NUM> may be applied to the antenna calibration apparatus shown in <FIG>. However, this embodiment of this application is not limited thereto. For a specific calibration process, refer to the related descriptions of the foregoing antenna calibration apparatus.

The ith antenna in the l antennas is used as a reference antenna, and a first compensation parameter δj of the jth antenna in the l antennas meets <MAT>. A radio frequency link corresponding to the jth antenna includes a receiver link and a transmitter link, the receiver link is connected to a receiver module, the transmitter link is connected to a transmitter module, the jth antenna is connected to an antenna used for testing, aj represents a second calibration signal received by the receiver module and sent by the antenna used for testing, bj represents a second calibration signal received by the receiver module and sent by the calibration circuit, cj represents a second calibration signal received by the antenna used for testing and sent by the transmitter module, dj represents a second calibration signal received by the calibration circuit and sent by the transmitter module, i is an integer and <NUM>≤i≤l, and j is an integer ranging from <NUM> to l.

In an optional embodiment, the obtaining a first calibration signal includes: obtaining the first calibration signal ej and fj corresponding to each antenna. The determining a second compensation parameter of each antenna based on the first compensation parameter and the first calibration signal includes: determining, based on the first compensation parameter δj of each antenna and the first calibration signal ej corresponding to each antenna, a second compensation parameter τTj of a transmitter link corresponding to each antenna; and determining, based on the first compensation parameter δj of each antenna and the first calibration signal fj corresponding to each antenna, a second compensation parameter τRj of a receiver link corresponding to each antenna. The calibrating each antenna based on the second compensation parameter includes: compensating for the transmitter link corresponding to each antenna with the second compensation parameter τTj of the transmitter link corresponding to each antenna, and compensating for the receiver link corresponding to each antenna with the second compensation parameter τRj of the receiver link corresponding to each antenna.

In an optional embodiment, the l antennas correspond to a first frequency band, and the antenna calibration apparatus further includes k antennas corresponding to a second frequency band, where k is an integer greater than or equal to <NUM>. The k antennas are respectively connected to first ends of k antenna filters, and second ends of the k antenna filters are respectively connected to k radio frequency links and each connected to the calibration circuit. The method further includes: obtaining a third calibration signal, where the third calibration signal is sent or received by the calibration circuit through a position between each antenna filter in the k antenna filters and a radio frequency link connected to the second end of each antenna filter in the k antenna filters; determining a first compensation parameter of each antenna in the k antennas; determining a second compensation parameter of each antenna in the k antennas based on the first compensation parameter of each antenna in the k antennas and the third calibration signal; and calibrating each antenna in the k antennas based on the second compensation parameter of each antenna in the k antennas.

It should be understood that, sequence numbers of the foregoing processes do not mean execution sequences.

In this application, "at least one" means one or more, and "a plurality of" means two or more. "And/or" describes an association relationship of associated objects, and indicates that three relationships may exist. For example, A and/or B may indicate the following cases: Only A exists; both A and B exist, or only B exists, where A and B may be singular or plural. The character "/" generally indicates that associated objects are in an "or" relationship. "At least one item (piece) of the following" or a similar expression thereof means any combination of these items and includes any combination of a single item (piece) or a plurality of items (pieces). For example, at least one item (piece) of a, b, or c may indicate a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c may be singular or plural.

It may be clearly understood by a person skilled in the art that, for the purpose of convenient and brief description, for a detailed working process of the foregoing systems, apparatuses, and units, refer to a corresponding process in the foregoing method embodiments.

In the several embodiments provided in this application, it should be understood that the disclosed system, apparatus, and method may be implemented in another manner. For example, the described apparatus embodiments are merely examples. For example, the unit division is merely logical function division and may be other division during actual implementation. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections may be implemented through some interfaces.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, and may be located in one position, or may be distributed on a plurality of network units. Some or all of the units may be selected depending on actual requirements to achieve the objectives of the solutions in the embodiments.

In addition, functional units in the embodiments of this application may be integrated into one processing unit, each of the units may exist alone physically, or two or more units are integrated into one unit.

When the functions are implemented in a form of a software functional unit and sold or used as an independent product, the functions may be stored in a computer-readable storage medium. Based on such an understanding, the technical solutions in this application essentially, or a part contributing to an existing technology, or some of the technical solutions may be implemented in a form of a software product. The computer software product is stored in a storage medium, and includes several instructions for instructing a computer device (which may be a personal computer, a server, a network device, or the like) to perform all or some of the steps of the methods in the embodiments of this application. The foregoing storage medium includes any medium that can store program code, such as a USB flash drive, a removable hard disk, a read-only memory (read-only memory, ROM), a random access memory (random access memory, RAM), a magnetic disk, or an optical disc.

Claim 1:
A base station, comprising:
l antennas (<NUM>), wherein l is an integer greater than or equal to <NUM>;
l antenna filters (<NUM>), wherein first ends of the l antenna filters (<NUM>) are respectively connected to the l antennas (<NUM>);
l radio frequency links (<NUM>), respectively connected to second ends of the l antenna filters (<NUM>); and
a calibration circuit (<NUM>), connected to each of the second ends of the l antenna filters (<NUM>), and configured to: send or receive, in an actual running process of a live network, a first calibration signal through a position between each antenna filter in the l antenna filters (<NUM>) and a radio frequency link (<NUM>) connected to the second end of each antenna filter; and
wherein the calibration circuit (<NUM>) is configured to:
determine a first compensation parameter of each antenna (<NUM>) in an equipment tabling process;
determine a second compensation parameter (<NUM>, <NUM>) of each antenna (<NUM>) based on the first compensation parameter and the first calibration signal in the actual running process of a live network; and
calibrate each antenna (<NUM>) based on the second compensation parameter (<NUM>, <NUM>);
wherein the ith antenna (<NUM>) in the l antennas (<NUM>) is used as a reference antenna, and a first compensation parameter δj of the jth antenna in the l antennas (<NUM>) meets: <MAT> wherein
a radio frequency link (<NUM>) corresponding to the jth antenna comprises a receiver link (<NUM>) and a transmitter link (<NUM>), the receiver link (<NUM>) is connected to a receiver module, the transmitter link (<NUM>) is connected to a transmitter module, the jth antenna is connected to an antenna (<NUM>) used for testing, aj represents a second calibration signal received by the receiver module and sent by the antenna (<NUM>) used for testing, bj represents a second calibration signal received by the receiver module and sent by the calibration circuit (<NUM>), cj represents a second calibration signal received by the antenna (<NUM>) used for testing and sent by the transmitter module, dj represents a second calibration signal received by the calibration circuit (<NUM>) and sent by the transmitter module, i is an integer and <NUM>≤i≤l, and j is an integer ranging from <NUM> to l;
wherein the second calibration signal is a calibration signal generated in the equipment tabling process.