WO2020227926A1

WO2020227926A1 - Radio network node with automatic gain control enhancement

Info

Publication number: WO2020227926A1
Application number: PCT/CN2019/086844
Authority: WO
Inventors: Yahui ZHAO; Ang FENG; Yanhui Zhao
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-05-14
Filing date: 2019-05-14
Publication date: 2020-11-19
Also published as: EP3970289A4; EP3970289A1

Abstract

Embodiments of the present disclosure provide a radio network node. The radio network node comprises a plurality of branches, a first combiner/splitter, a second combiner/splitter, an antenna calibration transceiver, and a digital processor. Each of the branches comprises an antenna, a coupler and a radio transceiver. The coupler is configured to couple a signal from the radio transceiver to the first combiner/splitter, and couple a signal from the antenna to the second combiner/splitter. The first combiner/splitter has a plurality of first ports coupled to the coupler and a second port coupled to the antenna calibration transceiver. The second combiner/splitter has a plurality of input ports coupled to the coupler and an output port coupled to the antenna calibration transceiver. The radio transceivers and the antenna calibration transceiver are connected to the digital processor.

Description

RADIO NETWORK NODE WITH AUTOMATIC GAIN CONTROL ENHANCEMENT

FIELD OF THE INVENTION

The present disclosure generally relates to radio communications, and more specifically, to a radio network node with automatic gain control (AGC) enhancement and related method in the radio network node.

BACKGROUND

This section introduces aspects that may facilitate a better understanding of the disclosure. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.

Currently, an Active Antenna System (AAS) is widely used in a radio network node, such as a base station, an eNB in LTE network, a gNB in 5G network, etc. Generally, AAS may comprise multiple antenna branches, which enable excellent network performance to be achieved by adapting advanced technologies, such as multi-user multi-input-multi-output (MU-MIMO) , beam-forming, etc.

Antenna array is a key part for AAS. To align phase between the antenna branches for beamforming, Antenna Calibration (AC) is needed for AAS. Generally, a standalone AC transceiver is deployed in the AAS, which can provide easy and flexible configuration with small hardware expense. It is also possible to multiplex with a radio transceiver for AC, which can avoid extra hardware cost. However, it would lead to more complexity in AC control and related algorithm. As a result, it is generally used in macro radio with small number of antennas, not in AAS. With the development of more and more radio systems, interference over the air becomes the biggest challenge in network planning. Automatic Gain Control (AGC) plays an indispensable role in radio communications, which extends a dynamic range by controlling attenuators in AAS. While a strong incoming signal occurs, the attenuators will be enabled to reduce input power of the incoming signal to fit a linear region of other components in AAS.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

Embodiments of the present disclosure propose solutions for AGC enhancement in a radio network node, which can improve robustness of AGC and avoid AGC toggling.

According to a first aspect of the present disclosure, there is provided a radio network node, which comprises a plurality of branches, a first combiner/splitter, a second combiner/splitter, an antenna calibration transceiver, and a digital processor. Each of the branches comprises an antenna, a coupler and a radio transceiver. The coupler is configured to couple a signal from the radio transceiver to the first combiner/splitter and couple a signal from the antenna to the second combiner/splitter. The first combiner/splitter has a plurality of first ports and a second port, the first port of the first combiner/splitter being coupled to the coupler, and the second port being coupled to the antenna calibration transceiver. The second combiner/splitter has a plurality of input ports and an output port, the input port of the second combiner/splitter being coupled to the coupler, and the output port being coupled to the antenna calibration transceiver. The radio transceivers and the antenna calibration transceiver are connected to the digital processor.

In accordance with an exemplary embodiment, the coupler may comprise a first directional coupler and a second directional coupler. The first directional coupler may have an input port, an output port and a coupling port. The input port of the first directional coupler may be coupled to the radio transceiver, the output port of the first directional coupler may be coupled to the antenna, and the coupling port of the first directional coupler may be coupled to the first combiner/splitter. The second directional coupler may have an input port, an output port and a coupling port. The input port of the second directional coupler may be coupled to the antenna, the output port of the second directional coupler may be coupled to the radio transceiver, and the coupling port of the second directional coupler may be coupled to the second combiner/splitter.

In accordance with an exemplary embodiment, the second directional coupler may be configured to receive an incoming signal within a guard period from the antenna via the input port of the second directional coupler, and generate a coupled incoming signal at the coupling port of the second directional coupler. The second combiner/splitter may be configured to combine the coupled incoming signals from the coupling ports of the second directional couplers into a combined signal, and output the combined signal to the antenna calibration transceiver.

In accordance with an exemplary embodiment, the first directional coupler may be configured to receive a transmitting signal from the radio transceiver via the input port of the first directional coupler, and generate a coupled transmitting signal at the coupling port of the first directional coupler. The first combiner/splitter may be configured to combine the coupled transmitting signals from the coupling ports of the first directional couplers into a combined signal and output the combined signal to the antenna calibration transceiver, and split a calibration signal from the antenna calibration transceiver into component calibration signals to be provided to the coupling ports of the first directional couplers.

In accordance with an exemplary embodiment, the coupler may be a bi-directional coupler which has a first input/output port, a second input/output port, a first coupling port and a second coupling port. The first input/output port may be coupled to the radio transceiver, the second input/output port may be coupled to the antenna, the first coupling port may be coupled to the first combiner/splitter, and the second coupling port may be coupled to the second combiner/splitter.

In accordance with an exemplary embodiment, the coupler may be configured to receive an incoming signal within a guard period from the antenna via the second input/output port of the coupler, and generate a coupled incoming signal at the second coupling port of the coupler. The second combiner/splitter may be configured to combine the coupled incoming signals from the second coupling ports of the couplers into a combined signal, and output the combined signal to the antenna calibration transceiver.

In accordance with an exemplary embodiment, the coupler may be configured to receive a transmitting signal from the radio transceiver via the first input/output port of the coupler, and generate a coupled transmitting signal at the first coupling port of the coupler. The first combiner/splitter may be configured to combine the coupled transmitting signals from the first coupling ports of the couplers into a combined signal and output the combined signal to the antenna calibration transceiver, and split a calibration signal from the antenna calibration transceiver into component calibration signals to be provided to the first coupling ports of the couplers.

In accordance with an exemplary embodiment, the antenna calibration transceiver may be configured to retrieve a baseband signal based on the combined signal, convert the baseband signal into a digital baseband signal, and provide the digital baseband signal to the digital processor. The digital processor may be configured to detect a power level of the digital baseband signal, and set a state of an automatic gain control function for the respective branches based on the power level.

In accordance with an exemplary embodiment, the digital processor may be further configured to sweep a first frequency band in which the antenna calibration transceiver operates to determine an amplitude and a frequency location of the digital baseband signal.

In accordance with an exemplary embodiment, the antenna calibration transceiver may be configured to retrieve a baseband signal based on the combined signal, convert the baseband signal into a digital baseband signal, detect a power level of the digital baseband signal, and provide the power level to the digital processor. The digital processor may be configured to set a state of an automatic gain control function for the respective branches based on the power level.

In accordance with an exemplary embodiment, the coupler or the second directional coupler may be further configured to receive an incoming signal within an uplink slot from the antenna via the second input/output port of the coupler or the input port of the second directional coupler, and generate a coupled incoming signal at the second coupling port of the coupler or the coupling port of the second directional coupler.

In accordance with an exemplary embodiment, the antenna calibration transceiver may be further configured to sweep a first frequency band in which the antenna calibration transceiver operates to determine an amplitude and a frequency location of the digital baseband signal.

In accordance with an exemplary embodiment, the first frequency band may cover a second frequency band in which the radio transceiver operates.

In accordance with an exemplary embodiment, the first frequency band may be a radio frequency (RF) band.

In accordance with an exemplary embodiment, the first frequency band may be swept with a sensing bandwidth.

According to a second aspect of the present disclosure, there is provided a method in a radio network node. The method comprises: coupling incoming signals from a plurality of antennas of the radio network node, combining the coupled incoming signals into a combined signal, detecting a power level of the combined signal, and setting a state of an automatic gain control function based on the power level.

In accordance with an exemplary embodiment, the incoming signals may be within a guard period.

In accordance with an exemplary embodiment, the incoming signals may be within an uplink slot.

In accordance with an exemplary embodiment, the method may further comprise sweeping a calibration frequency band of the radio network node to determine an amplitude and a frequency location of the combined signal.

In accordance with an exemplary embodiment, the calibration frequency band may cover an operating frequency band of the radio network node.

In accordance with an exemplary embodiment, the calibration frequency band may be a radio frequency (RF) band.

In accordance with an exemplary embodiment, the calibration frequency band may be swept with a sensing bandwidth.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure itself, the preferable mode of use and further objectives are best understood by reference to the following detailed description of the embodiments when read in conjunction with the accompanying drawings, in which:

Fig. 1 is a diagram illustrating an exemplary radio network node with antenna calibration;

Fig. 2 is a diagram illustrating a radio network node according to some embodiments of the present disclosure;

Fig. 3 is a diagram illustrating an exemplary structure of the coupler in the radio network node as shown in Fig. 2;

Fig. 4 is a diagram illustrating another exemplary structure of the coupler in the radio network node as shown in Fig. 2;

Fig. 5 is a diagram illustrating spectrum sensing in GP in the radio network node according to some embodiments of the present disclosure;

Fig. 6 is a diagram illustrating exemplary frequency bands for the radio network node according to some embodiments of the present disclosure;

Fig. 7 is a diagram illustrating an exemplary receiving filter chain in the radio network node according to some embodiments of the present disclosure;

Fig. 8 is a diagram illustrating spectrum sensing in both GP and UL slot in the radio network node according to some embodiments of the present disclosure; and

Fig. 9 is a diagram illustrating a method performed in a radio network node according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. It should be understood that these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the present disclosure. Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present disclosure should be or are in any single embodiment of the disclosure. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Furthermore, the described features, advantages, and characteristics of the disclosure may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the disclosure may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the disclosure.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as new radio (NR) , long term evolution (LTE) , LTE-Advanced, wideband code division multiple access (WCDMA) , high-speed packet access (HSPA) , and so on. Furthermore, the communications between a terminal device and a network node in the communication network may be performed according to any suitable generation communication protocols, including, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , 4G, 4.5G, 5G communication protocols, and/or any other protocols either currently known or to be developed in the future.

The term “network node” refers to a network device in a communication network via which a terminal device accesses to the network and receives services therefrom. The network node or network device may refer to a base station (BS) , an access point (AP) , a multi-cell/multicast coordination entity (MCE) , a controller or any other suitable device in a wireless communication network. The BS may be, for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNodeB or gNB) , an IAB node, a remote radio unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, a low power node such as a femto, a pico, and so forth.

Yet further examples of the network node comprise multi-standard radio (MSR) radio equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs) , base transceiver stations (BTSs) , transmission points, transmission nodes, positioning nodes and/or the like. More generally, however, the network node may represent any suitable device (or group of devices) capable, configured, arranged, and/or operable to enable and/or provide a terminal device access to a wireless communication network or to provide some service to a terminal device that has accessed to the wireless communication network.

As used herein, the terms “first” , “second” and so forth refer to different elements. The singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” as used herein, specify the presence of stated features, elements, and/or components and the like, but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof. The term “based on” is to be read as “based at least in part on” . The term “one embodiment” and “an embodiment” are to be read as “at least one embodiment” . The term “another embodiment” is to be read as “at least one other embodiment” . Other definitions, explicit and implicit, may be included below.

Fig. 1 shows an exemplary radio network node 100 with antenna calibration (AC) . As shown in Fig. 1, the radio network node 100 may comprise multiple antenna branches 110. Each antenna branch 110 may comprise an antenna 120, a directional coupler 130 and a radio transceiver 140. The directional coupler 130 is coupled between the antenna 120 and the radio transceiver 140. The radio transceiver 140 comprises a radio transmitter 1401 for transmitting a radio signal via the antenna 120 and a radio receiver 1402 for receiving a radio signal via the antenna 120. As shown, a standalone AC transceiver 150 is deployed in the exemplary radio network node 100. The AC transceiver 150 may comprise an AC transmitter 1501 for transmitting a calibration signal and an AC receiver 1502 for receiving a calibration signal. In an antenna calibration process for the radio transmitter 1401, for each of the antenna branches 110, a calibration signal is transmitted from the radio transmitter 1401 to the directional coupler 130. The directional coupler 130 couples the calibration signal and provides the coupled signal to the AC receiver 1502 via a combiner/splitter 160. In an antenna calibration process of the radio receiver 1402, for each of the antenna branches 110, a calibration signal is transmitted from the AC transmitter 1501 to the directional coupler 130 via the combiner/splitter 160, and the directional coupler 130 couples the calibration signal to the radio receiver 1402. In addition, a switch 170 is used to selectively connect one of the AC transmitter 1501 and the AC receiver 1502 to the combiner/splitter 160.

When the radio network node 110 receives the radio signal, AGC will be performed on a receiving path of each antennal branch. In Time Division Duplex (TDD) mode, it is difficult to set a proper initial state of AGC in each uplink (UL) slot. Generally, there are two methods to set the initial state of AGC. One is to always set a zero state (i.e. no attenuation) as the initial state, and the other is to hold the same state as in the previous UL slot. The first method is good for dynamic blocking, but it might introduce multiple glitches in state transitions. The second method is good for static blocking, but it might introduce unnecessary attenuation and lead to higher noise figure.

In-band blocking can result in AGC toggling because an AGC detector in a digital chip of the radio network node cannot properly estimate a correct interference level. Currently, proprietary Fast Over-Range (FOVR) and Peak Hold Meter (PHM) are utilized to handle such issue. However, they need specific chipset and extra cost for these functions. In addition, the AGC detector is located after an analog/digital converter (ADC) , and thus the AGC detector might have limited bandwidth due to filters in the receiving path.

Therefore, it would be desirable to provide a solution for AGC enhancement in a radio network node to improve stability of AGC and avoid AGC toggling.

In accordance with some exemplary embodiments, the present disclosure provides an improved solution for AGC enhancement in a radio network node. The solution may be applied to a radio network node with AAS. In the radio network node, each coupler can execute both forward coupling and reverse coupling. Thus, external interference from the antennas can be received by the AC transceiver, and the interference level can be detected properly to assist AGC.

It is noted that some embodiments of the present disclosure are mainly described in relation to 5G specifications being used as non-limiting examples for certain exemplary network configurations and system deployments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples and embodiments, and does not limit the present disclosure naturally in any way. Rather, any other system configuration or radio technologies may equally be utilized as long as exemplary embodiments described herein are applicable.

Fig. 2 is a diagram illustrating a radio network node 200 according to some embodiments of the present disclosure. In accordance with an exemplary embodiment, the radio network node may be a base station such as an NB, an eNB or a gNB.

As shown in Fig. 2, the radio network node 200 may comprise a plurality of branches 210. Each of the branches 210 may comprise an antenna 202, a coupler 204 and a radio transceiver 206. The radio network node 200 may further comprise a first combiner/splitter 220, a second combiner/splitter 230, an antenna calibration transceiver 240 and a digital processor 250.

In some embodiments, the coupler 204 may be configured to couple a signal from the radio transceiver 206 to the first combiner/splitter 220 and couple a signal from the antenna 202 to the second combiner/splitter 230. Therefore, the coupler 204 can connect not only the radio path to the antenna but also the antenna calibration path to the antenna, and thus have both a forward coupling path and a reverse coupling path.

In some embodiments, the radio transceiver 206 may comprise a radio transmitter for transmitting a radio signal via the antenna 202 and a radio receiver for receiving a radio signal via the antenna 202.

In some embodiments, the first combiner/splitter 220 may have a plurality of first ports 2202 and a second port 2204. The first ports 2202 may be coupled to the respective couplers 204 of the branches 210. The second port 2204 may be coupled to the antenna calibration transceiver 240. In some embodiments, the first combiner/splitter 220 may be configured to combine signals from the respective couplers 204 via the first ports 2202 into a combined signal and provide the combined signal to the antenna calibration transceiver 240 via the second port 2204. In some embodiments, the first combiner/splitter 220 may be configured to split a calibration signal from the antenna calibration transceiver 240 via the second port 2204 into component calibration signals and provide the component calibration signals to the respective couplers 204.

In some embodiments, the second combiner/splitter 230 may have a plurality of input ports 2302 and an output port 2304. The input ports 2302 may be coupled to the respective couplers 204 of the branches 210. The output port 2304 may be coupled to the antenna calibration transceiver 240. In some embodiments, the second combiner/splitter 230 may be configured to combine signals from the respective couplers 204 via the input ports 2302 into a combined signal and provide the combined signal to the antenna calibration transceiver 240 via the output port 2304.

In some embodiments, the antenna calibration transceiver 240 may comprise an antenna calibration transmitter for transmitting a calibration signal and an antenna calibration receiver for receiving a calibration signal. Further, the radio network node 200 may comprise a first switch 260 and a second switch 270. The first switch 260 is configured to selectively connect the first combiner/splitter 220 to one of the antenna calibration transmitter and the antenna calibration receiver. The second switch 270 is configured to selectively connect the antenna calibration receiver to one of the first combiner/splitter 220 and the second combiner/splitter 230.

In some embodiments, the digital processor 250 may be connected to the respective radio transceivers 206 of the branches 210 and the antenna calibration transceiver 240, and configured to perform AGC on the respective branches 210 based on radio signal information via the radio transceivers 206 and interference information via the antenna calibration transceiver 240.

Fig. 3 illustrates an exemplary structure of the coupler 204 in the radio network node 200. As shown in Fig. 3, the coupler 204 comprises two directional couplers, i.e. a first directional coupler 302 and a second directional 304. The first directional coupler 302 may have an input port 3022, an output port 3024, a coupling port 3026, and an isolation port 3028. The input port 3022 is coupled to the radio transceiver 206, the output port 3024 is coupled to the antenna 202, and the coupling port 3026 is coupled to the first combiner/splitter 220. The isolation port 3028 may be grounded via a resistor. Therefore, the first directional coupler 302 can receive a transmitting signal from the radio transceiver 206 via the input port 3022, and generate a coupled transmitting signal at the coupling port 3026 to be provided to the first combiner/splitter 220. In this way, the first directional coupler 302 can implement the forward coupling.

In Fig. 3, the second directional coupler 304 has an input port 3042, an output port 3044, a coupling port 3046, and an isolation port 3048. The input port 3042 is coupled to the antenna 202, the output port 3044 is coupled to the radio transceiver 206, and the coupling port 3046 is coupled to the second combiner/splitter 230. The isolation port 3048 may be grounded via a resistor. Therefore, the second directional coupler 304 can receive an incoming signal from the antenna 202 via the input port 3042, and generate a coupled incoming signal at the coupling port 3026 to be provided to the second combiner/splitter 230. In this way, the second directional coupler 304 can implement the reverse coupling.

In the case of the coupler 204 as shown in Fig. 3, the first combiner/splitter 220 may combine the coupled transmitting signals from the respective coupling ports 3026 of the first directional couplers 302 into a combined signal and output the combined signal to the antenna calibration transceiver 240. The first combiner/splitter 220 may also split a calibration signal from the antenna calibration transceiver 240 into component calibration signals and provide the component calibration signals to the respective coupling ports 3026 of the first directional couplers 302. The second combiner/splitter 230 may combine the coupled incoming signals from the respective coupling ports 3046 of the second directional couplers 304 into a combined signal, and output the combined signal to the antenna calibration transceiver 240.

Fig. 4 illustrates another exemplary structure of the coupler 204 in the radio network node 200. As shown in Fig. 4, the coupler 204 is a bi-directional coupler. In some embodiments, the bi-directional coupler may have a first input/output port 402, a second input/output port 404, a first coupling port 406 and a second coupling port 408. The first input/output port 402 is coupled to the radio transceiver 206, the second input/output port 404 is coupled to the antenna 202, the first coupling port 406 is coupled to the first combiner/splitter 220, and the second coupling port 408 is coupled to the second combiner/splitter 230. Therefore, the bi-direction coupler can receive a transmitting signal from the radio transceiver 206 via the first input/output port 402, and generate a coupled transmitting signal at the first coupling port 406. In this case, the second input/output port 404 may act as an output port, and the second coupling port 408 may act as an isolation port. The bi-direction coupler can also receive an incoming signal from the antenna 202 via the second input/output port 404, and generate a coupled incoming signal at the second coupling port 408. In this case, the first input/output port 402 may act as an output port, and the first coupling port 406 may act as an isolation port.

In the case of the coupler 204 as shown in Fig. 4, the first combiner/splitter 220 may combine the coupled transmitting signals from the respective first coupling ports 406 into a combined signal, and output the combined signal to the antenna calibration transceiver 240. The first combiner/splitter 220 may also split a calibration signal from the antenna calibration transceiver 240 into component calibration signals, and provide the component calibration signals to the respective first coupling ports 406. The second combiner/splitter 230 may combine the coupled incoming signals from the respective second coupling ports 408 into a combined signal, and output the combined signal to the antenna calibration transceiver 240.

Returning to Fig. 2, in some embodiments, the antenna calibration transceiver 240 may process the combined signal. For example, the antenna calibration transceiver 240 may retrieve a baseband signal based on the combined signal, convert the baseband signal into a digital baseband signal, and provide the digital baseband signal to the digital processor 250. Then the digital processor 250 may detect a power level of the digital baseband signal, and set a state of an AGC function for the respective branches based on the power level. In an embodiment, the digital processor 250 may comprise an AGC detector to detect the power level. In this case, the existing antenna calibration transceiver and AGC detector can be used, and no extra hardware cost is needed.

In some embodiments, in addition to retrieving the baseband signal based on the combined signal and converting the baseband signal into the digital baseband signal, the antenna calibration transceiver 240 may detect the power level of the digital baseband signal and provide the power level to the digital processor 250. Then the digital processor 250 may set the state of the AGC function based on the power level. In this case, instead of the AGC detector, the antenna calibration transceiver 240 may comprise a detector to detect the power level.

In some embodiments, the second directional coupler 304 as shown in Fig. 3 or the bi-directional coupler as shown in Fig. 4 may couple the incoming signal within a guard period (GP) to the second combiner/splitter 230. In 5G New Radio (NR) , GP is composed of one or more empty Orthogonal Frequency Division Multiplexing (OFDM) symbols to facilitate switching between downlink (DL) and uplink (UL) . As shown in Fig. 5, GP is placed in the front of a UL slot. The incoming signal in GP from the antenna 202 shall be interference. Therefore, in GP before the UL slot, the antenna calibration transceiver 240 is connected to the second combiner/splitter 230 via the second switch 270 under the control of a spectrum sensing (SS) enable signal. Thus, the antenna calibration transceiver 240 may receive all the interference from the antennas 202 before the UL slot. The power level of the interference may be detected by the antenna calibration transceiver 240 or the digital processor 250. The power level can be used as an indicator of AGC to help the AGC function to set the initial state of AGC to a proper state. This solution can reduce occurrence of glitch in dynamic blocking while keeping as low noise figure as possible in static blocking.

Generally, the AGC detector can detect the power level of the signal in an operating frequency band (corresponding to “a second frequency band” in claims) in which the radio transceiver 206 operates. If the interference exists outside of the operating frequency band, the AGC detector cannot detect the power level of the interference and will give a wrong indication for state transition of the AGC function, thereby resulting in the AGC toggling. To avoid the AGC toggling, in some embodiments, the antenna calibration transceiver 240 may operate in a different frequency band from the operating frequency band. In an embodiment, the frequency band (hereinafter referred to as “a first frequency band” or “a calibration frequency band” ) in which the antenna calibration transceiver 240 operates covers the operating frequency band. For example, the first frequency band is a radio frequency (RF) band. In this way, the antenna calibration transceiver 240 can receive the interference within the RF band. As the antenna calibration transceiver 240 can work in the wider frequency band, in the UL slot, the power level of the interference can be detected properly, even if the interference exists outside of the operating frequency band. Thus, the state of the AGC function can be set to the proper state, thereby avoiding the AGC toggling.

In some embodiments, after detecting the power level of the digital baseband signal, the antenna calibration transceiver 240 or the digital processor 250 may further sweep the calibration frequency band to determine amplitude and frequency location of the digital baseband signal. In an embodiment, the calibration frequency band may be swept with a sensing bandwidth. Fig. 6 illustrates exemplary calibration frequency band and operating frequency band for the radio network node according to some embodiments of the present disclosure. As shown in Fig. 6, RF BW denotes the calibration frequency band, RX BW denotes the operating frequency band, SS BW1 and SS BW2 denote two examples of the sensing bandwidth.

In some embodiments, a receiving (RX) filter chain may be implemented in the digital processor 250 or the antenna calibration transceiver 240 to determine the amplitude and frequency location of the interference, as shown in Fig. 7. In Fig. 7, a numerically controlled oscillator (NCO) is used to translate wanted signals (i.e. the signals in the operating frequency band) to zero frequency. A channel filter is used to identify the unwanted signals (i.e. the signals outside of the operating frequency band) . The RX filter chain may comprise a decimation filter to decrease a sample rate. The NCO and the channel filter can realize frequency sweeping, thereby extracting the frequency information in addition to energy or cyclosationarity detection.

The energy detection may be performed by an energy detector. Assuming the received signal as x (n) , the energy E can be expressed as

where, N _GP denotes the length of GP, n denotes a sample index within GP.

In the cyclosationarity detection, cyclostationarity in a signal or in its statistics can be exploited to figure out the interference. Cyclostationarity exists in a periodical signal, and a non-periodical signal indeed also has this property. For the received signal as x (n) , the cyclic spectral density (CSD) R (τ, α) can be expressed as

R (τ, α) = E {x (n) x* (n+τ) e ^j2παn}

where, E {·} denotes an expectation, x* (n) denotes a conjugate of x (n) , τ and α indicate correlation spacing in time domain and frequency domain respectively.

In some embodiments, in the case that the antenna calibration transceiver 240 can detect a power level of a signal, the second directional coupler 304 as shown in Fig. 3 or the bi-directional coupler as shown in Fig. 4 may further couple the incoming signal within the UL slot to the second combiner/splitter 230. In this case, the incoming signal in the UL slot may comprise an UL signal and interference. In the UL slot, the antenna calibration transceiver 240 is connected to the second combiner/splitter 230 under the control of the SS enable signal, as shown in Fig. 8. Thus, the antenna calibration transceiver 240 may receive all the signals from the antennas 202 in the UL slot. Then the antenna calibration transceiver 240 may use the RX channel filter chain as shown in Fig. 7 to detect the power level of the interference. The power level will be provided to the digital processor 250 to decide the state of the AGC function.

It can be therefore seen that, with the proposed solutions for the radio network node with the AGC enhancement according to the above embodiments, the power level of the external interference can be properly detected to initialize the state of the AGC function. Moreover, the AGC toggling due to the in-band blocking can be avoided.

Fig. 9 illustrates a flowchart of a method 900 implemented in a radio network node. The radio network node may be a base station as shown in Fig. 2.

As shown in Fig. 9, in block 902, the radio network node may couple the incoming signals from a plurality of antennas. In some embodiments, the incoming signals may be within the GP before the UL slot. In some embodiments, the incoming signals may further be within the UL slot.

Then in block 904, the radio network node may combine the coupled incoming signals into a combined signal. The radio network node then may detect the power level of the combined signal, as shown in block 906. The power level may be used by the radio network node to set a state of the AGC function, as shown in block 908.

In some embodiments, the radio network node may further sweep the calibration frequency band to determine the amplitude and frequency location of the combined signal.

The various blocks shown in Fig. 9 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function (s) . The schematic flow chart diagrams described above are generally set forth as logical flow chart diagrams. As such, the depicted order and labeled steps are indicative of specific embodiments of the presented methods. Other steps and methods may be conceived that are equivalent in function, logic, or effect to one or more steps, or portions thereof, of the illustrated methods. Additionally, the order in which a particular method occurs may or may not strictly adhere to the order of the corresponding steps shown.

In general, the various exemplary embodiments may be implemented in hardware or special purpose chips, circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

As such, it should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components such as integrated circuit chips and modules. It should thus be appreciated that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit, where the integrated circuit may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor, a digital signal processor, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

It should be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium such as a hard disk, optical disk, removable storage media, solid state memory, random access memory (RAM) , etc. As will be appreciated by one of skill in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or partly in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA) , and the like.

The present disclosure includes any novel feature or combination of features disclosed herein either explicitly or any generalization thereof. Various modifications and adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments of this disclosure.

Claims

A radio network node (200) comprising a plurality of branches (210) , a first combiner/splitter (220) , a second combiner/splitter (230) , an antenna calibration transceiver (240) , and a digital processor (250) ;

wherein each of the branches (210) comprises an antenna (202) , a coupler (204) and a radio transceiver (206) ;

wherein the coupler (204) is configured to couple a signal from the radio transceiver (206) to the first combiner/splitter (220) and couple a signal from the antenna (202) to the second combiner/splitter (230) ;

wherein the first combiner/splitter (220) has a plurality of first ports and a second port, the first port of the first combiner/splitter (220) being coupled to the coupler (204) , and the second port being coupled to the antenna calibration transceiver (240) ;

wherein the second combiner/splitter (230) has a plurality of input ports and an output port, the input port of the second combiner/splitter (230) being coupled to the coupler, and the output port being coupled to the antenna calibration transceiver (240) ; and

wherein the radio transceivers (206) and the antenna calibration transceiver (240) are connected to the digital processor (250) .
The radio network node (200) according to claim 1, wherein the coupler (204) comprises a first directional coupler (302) and a second directional coupler (304) ,

wherein the first directional coupler (302) has an input port (3022) , an output port (3024) and a coupling port (3026) , wherein the input port (3022) of the first directional coupler (302) is coupled to the radio transceiver (206) , the output port (3024) of the first directional coupler (302) is coupled to the antenna (202) , and the coupling port (3026) of the first directional coupler (302) is coupled to the first combiner/splitter (220) ; and

wherein the second directional coupler (304) has an input port (3042) , an output port (3044) and a coupling port (3046) , wherein the input port (3042) of the second directional coupler (304) is coupled to the antenna (202) , the output port (3044) of the second directional coupler (304) is coupled to the radio transceiver (206) , and the coupling port (3046) of the second directional coupler (304) is coupled to the second combiner/splitter (230) .
The radio network node (200) according to claim 2,

wherein the second directional coupler (304) is configured to receive an incoming signal within a guard period from the antenna (202) via the input port (3042) of the second directional coupler (304) , and generate a coupled incoming signal at the coupling port (3046) of the second directional coupler (304) ; and

wherein the second combiner/splitter (230) is configured to combine the coupled incoming signals from the coupling ports (3046) of the second directional couplers (304) into a combined signal, and output the combined signal to the antenna calibration transceiver (240) .
The radio network node (200) according to claim 2 or 3,

wherein the first directional coupler (302) is configured to receive a transmitting signal from the radio transceiver (206) via the input port (3022) of the first directional coupler (302) , and generate a coupled transmitting signal at the coupling port (3026) of the first directional coupler (302) ; and

wherein the first combiner/splitter (220) is configured to combine the coupled transmitting signals from the coupling ports (3026) of the first directional couplers (302) into a combined signal and output the combined signal to the antenna calibration transceiver (240) , and split a calibration signal from the antenna calibration transceiver (240) into component calibration signals to be provided to the coupling ports (3026) of the first directional couplers (302) .
The radio network node (200) according to claim 1, wherein the coupler (204) is a bi-directional coupler which has a first input/output port (402) , a second input/output port (404) , a first coupling port (406) and a second coupling port (408) , wherein the first input/output port (402) is coupled to the radio transceiver (206) , the second input/output port (404) is coupled to the antenna (202) , the first coupling port (406) is coupled to the first combiner/splitter (220) , and the second coupling port (408) is coupled to the second combiner/splitter (230) .
The radio network node (200) according to claim 5,

wherein the coupler (204) is configured to receive an incoming signal within a guard period from the antenna (202) via the second input/output port (404) of the coupler (204) , and generate a coupled incoming signal at the second coupling port (408) of the coupler (204) ; and

wherein the second combiner/splitter (230) is configured to combine the coupled incoming signals from the second coupling ports (408) of the couplers (204) into a combined signal, and output the combined signal to the antenna calibration transceiver (240) .
The radio network node (200) according to claim 5 or 6,

wherein the coupler (204) is configured to receive a transmitting signal from the radio transceiver (206) via the first input/output port (402) of the coupler (204) , and generate a coupled transmitting signal at the first coupling port (406) of the coupler (204) ; and

wherein the first combiner/splitter (220) is configured to combine the coupled transmitting signals from the first coupling ports (206) of the couplers (204) into a combined signal, output the combined signal to the antenna calibration transceiver (240) , and split a calibration signal from the antenna calibration transceiver (240) into component calibration signals to be provided to the first coupling ports of the couplers (206) .
The radio network node (200) according to any one of claims 1 to 7, wherein the antenna calibration transceiver (240) is configured to retrieve a baseband signal based on the combined signal, convert the baseband signal into a digital baseband signal, and provide the digital baseband signal to the digital processor (250) ; and

wherein the digital processor (250) is configured to detect a power level of the digital baseband signal, and set a state of an automatic gain control function for the respective branches (210) based on the power level.
The radio network node (200) according to claim 8, wherein the digital processor (250) is further configured to sweep a first frequency band in which the antenna calibration transceiver (240) operates to determine an amplitude and a frequency location of the digital baseband signal.
The radio network node (200) according to any one of claims 1 to 7, wherein the antenna calibration transceiver (240) is configured to retrieve a baseband signal based on the combined signal, convert the baseband signal into a digital baseband signal, detect a power level of the digital baseband signal, and provide the power level to the digital processor (250) ; and

wherein the digital processor (250) is configured to set a state of an automatic gain control function for the respective branches (210) based on the power level.
The radio network node (200) according to claim 10, wherein the coupler (204) or the second directional coupler (304) is further configured to receive an incoming signal within an uplink slot from the antenna (202) via the second input/output port (404) of the coupler (204) or the input port (3042) of the second directional coupler (304) , and generate a coupled incoming signal at the second coupling port (408) of the coupler (204) or the coupling port (3046) of the second directional coupler (304) .
The radio network node (200) according to claim 10 or 11, wherein the antenna calibration transceiver (240) is further configured to sweep a first frequency band in which the antenna calibration transceiver (240) operates to determine an amplitude and a frequency location of the digital baseband signal.
The radio network node (200) according to claim 9 or 12, wherein the first frequency band covers a second frequency band in which the radio transceiver (206) operates.
The radio network node (200) according to claim 13, wherein the first frequency band is a radio frequency (RF) band.
The radio network node (200) according to claim 9 or 12, wherein the first frequency band is swept with a sensing bandwidth.
A method (900) in a radio network node (200) comprising:

coupling (902) incoming signals from a plurality of antennas of the radio network node;

combining (904) the coupled incoming signals into a combined signal;

detecting (906) a power level of the combined signal; and

setting (908) a state of an automatic gain control function based on the power level.
The method (900) according to claim 16, wherein the incoming signals are within a guard period.
The method (900) according to claim 16 or 17, wherein the incoming signals are within an uplink slot.
The method (900) according to claim any one of claims 16 to 18, further comprising:

sweeping a calibration frequency band of the radio network node to determine an amplitude and a frequency location of the combined signal.
The method (900) according to claim 19, wherein the calibration frequency band covers an operating frequency band of the radio network node.
The method (900) according to claim 20, wherein the calibration frequency band is a radio frequency (RF) band.
The method (900) according to any one of claims 20 to 21, wherein the calibration frequency band is swept with a sensing bandwidth.