MIMO antenna array for frequency division duplexing

Abstract

Disclosed herein is a radio frequency (RF) unit and a method of operating the RF unit. The RF unit includes an antenna array, and the antenna array includes a plurality of antenna elements. A first group of the plurality of antenna elements is configured to operate in a first mode, and a second group of the plurality of antenna elements is configured to operate in a second mode. In the first mode, the first group of the plurality of antenna elements is configured to transmit and receive. In the second mode, the second group of the plurality of antenna elements is configured to only receive.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to self-interference radio antenna systems. More specifically, the present disclosure relates to massive multiple-input multiple-output (MIMO) arrays that support simultaneous transmission and reception of signals within a time-division duplex (TDD) band. BACKGROUND

[0002] Limited coverage has been identified as one of the key challenges for 5G cellular communication systems. Many 5G bands are at high frequencies compared to 4G bands, which results in higher path loss, and have wider bandwidths compared to 4G bands, which results in lower power spectral density (PSD). These factors affect the transmission range of wireless links between 5G devices. Therefore, to improve the signal-to-noise ratio (SNR) of a base station (BS) for better reception, it is often necessary to allocate less than the full spectrum bandwidth to a cell edge user.

[0003] Furthermore, most 5G bands are allocated as time-division duplex (TDD) bands. While TDD bands have the advantage of flexibly allocating downlink (DL) and uplink (UL) resources in the time domain, the UL resource allocation is inevitably less than a frequency-division duplex (FDD) system. The limited time and limited frequency spectrum allocated to a user equipment (UE) for UL transmission is a major cause of limited coverage for 5G systems. SUMMARY

[0004] SOLUTION TO THE PROBLEM

[0005] Embodiments of the present disclosure provide a radio frequency (RF) unit. The RF unit includes an antenna array, and the antenna array includes a plurality of antenna elements. A first group of the plurality of antenna elements is configured to operate in a first mode, and a second group of the plurality of antenna elements is configured to operate in a second mode. In the first mode, the first group of the plurality of antenna elements is configured to transmit and receive. In the second mode, the second group of the plurality of antenna elements is configured to only receive.

[0006] In another embodiment of the above RF unit, the second set of antenna elements of the plurality of antenna elements are also configured to operate in the first mode, and in the first mode, the second set of antenna elements of the plurality of antenna elements are configured to receive only. At least some of the plurality of antenna elements can include a plurality of antennas arranged in a subarray configuration. The first set of antenna elements of the plurality of antenna elements can include a massive multiple-input multiple-output (MIMO) array, and antenna elements comprising the second set of antenna elements of the plurality of antenna elements can be disposed adjacent to at least one edge of the massive MIMO array. The RF unit can also include an electromagnetic (EM) isolation element disposed between the first set of antenna elements of the plurality of antenna elements and the second set of antenna elements of the plurality of antenna elements.

[0007] In yet another embodiment of the above RF unit, the first set of antenna elements of the plurality of antenna elements are also configured to operate in the second mode. In the second mode, the first set of antenna elements of the plurality of antenna elements are configured to transmit only, and the second set of antenna elements of the plurality of antenna elements are configured to receive in the same time slots that the first set of antenna elements of the plurality of antenna elements transmit. The first set of antenna elements of the plurality of antenna elements can also be configured to receive a sounding reference signal (SRS) in a first time slot in the first mode, and transmit a beamformed signal based on the received SRS in a second time slot in the second mode. In the second mode, the first set of antenna elements of the plurality of antenna elements are configured to transmit in a first frequency allocation, the second set of antenna elements of the plurality of antenna elements are configured to receive in a second frequency allocation, and the first frequency allocation and the second frequency allocation either overlap or do not overlap. The first frequency allocation and the second frequency allocation comprise a third frequency allocation, and in the first mode, the first set of antenna elements of the plurality of antenna elements are configured to transmit and receive in the third frequency allocation. The size of the first frequency allocation and the size of the second frequency allocation are dynamic between time slots.

[0008] In one embodiment, a method of operating an RF unit is provided. The method includes transmitting a first transmit signal and receiving a first receive signal via a first set of antenna elements of a plurality of antenna elements of an antenna array of the RF unit in a first mode, and receiving a second receive signal via a second set of antenna elements of the plurality of antenna elements of the antenna array of the RF unit in a second mode.

[0009] In another embodiment of the above-described method of the RF unit, the method includes receiving, in the first mode, at least some of the first receive signals via the second set of the plurality of antenna elements. The above-described method of the RF unit can also include transmitting, in the second mode, second transmit signals via the first set of the plurality of antenna elements, and receiving, in the second mode, the second receive signals via the second set of the plurality of antenna elements in the same time slots that the first set of the plurality of antenna elements transmits the second transmit signals. In some embodiments, the method further includes receiving, in the first mode, sounding reference signals (SRS) via the first set of the plurality of antenna elements in first time slots, and transmitting, in the second mode, beamformed signals based on the received SRS via the first set of the plurality of antenna elements in second time slots. In some embodiments, the second transmit signals are transmitted in a first frequency allocation and the second receive signals are received in a second frequency allocation, where the first frequency allocation and the second frequency allocation either overlap or do not overlap. In some embodiments, the first frequency allocation and the second frequency allocation comprise a third frequency allocation, and the method further includes transmitting, in the first mode, the first transmit signals and receiving the first receive signals in the third frequency allocation via the first set of the plurality of antenna elements. In some embodiments, a size of the first frequency allocation and a size of the second frequency allocation are dynamic between time slots.

[0010] Other technical features can be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

[0011] Before undertaking a detailed description of the present application, it can be advantageous to set forth definitions of certain terms and phrases used in this patent document. The term “coupled” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “transmit,” “receive,” and “communicate,” as well as derivatives thereof, encompass both direct and indirect communication. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and / or. The phrase “associated with,” as well as derivatives thereof, means to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have a property of, have relations with, or the like. The term “controller” means any device, system or part thereof that controls at least one operation. Such a controller can be implemented in hardware or a combination of hardware and software and / or firmware. The functionality associated with any particular controller can be centralized or distributed, whether locally or remotely. The phrase “at least one of” followed by a list of two or more items, means that any of the listed items can be employed by itself, as well as any combination of two or more of the listed items. For example, “at least one of A, B, and C” means that only A, or only B, or only C, or any combination of the three, can be employed.

[0012] Furthermore, various functions described below can be implemented or supported by one or more computer programs, each of which is formed from computer readable program code and embodied in a computer readable medium. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof that can be implemented by suitable computer readable program code. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links. Non-transitory computer readable media include media that can be permanently stored and media that can be stored and overwritten, such as a rewritable optical disc or an erasable memory device.

[0013] Definitions for other certain words and phrases are provided throughout this patent document. Those of ordinary skill in the art should understand that in many if not most instances, such definitions apply to prior as well as future uses of such defined words and phrases. Attached Figure Description

[0014] To gain a more complete understanding of this disclosure and its advantages, reference is now made to the following description in conjunction with the accompanying drawings, wherein like reference numerals denote like parts:

[0015] FIG. 1A An exemplary wireless system operating in accordance with the principles of this disclosure is shown;

[0016] FIG. 1B It shows the result of FIG. 1A Example spectrum diagram of a wireless system performing cross-division duplex (XDD) mode operation;

[0017] FIG. 2 An example base station (BS) according to an embodiment of the present disclosure is shown;

[0018] FIGS. 3A-8B Different embodiments of the example XDD massive MIMO antenna array according to embodiments of the present disclosure are shown;

[0019] FIG. 9A A block diagram of an example XDD operation according to an embodiment of the present disclosure is shown;

[0020] FIG. 9B It shows in FIG. 9A Example spectrum diagrams of signals at various points during the XDD operation;

[0021] FIG. 10 Time-frequency diagrams of example TDD and XDD modes of a BS according to embodiments of the present disclosure are shown; and

[0022] FIG. 11 The process of operating the RF unit according to various embodiments of the present disclosure is illustrated. Detailed Implementation

[0023] The following discussion FIGS. 1A-11 The various embodiments used to describe the principles of this disclosure in this patent document are merely illustrative and should not be construed as limiting the scope of this disclosure in any way. Those skilled in the art will understand that the principles of this disclosure can be implemented in any suitably arranged system or device.

[0024] Embodiments of the present disclosure recognize that it would be beneficial to enhance the UL coverage of a TDD carrier (i.e., the range from a UE where UL transmissions can be received by a BS) without sacrificing DL data throughput. To address this issue, embodiments of the present disclosure recognize that within the spectrum of the same TDD band, cross division duplexing (XDD) enables a UE to transmit UL signals while a BS simultaneously transmits DL signals. Compared to a TDD system, the uplink of the UE can be scheduled with more opportunities in both time and frequency domains, and thus the coverage can be extended compared to a TDD system.

[0025] Embodiments of the present disclosure recognize that TDD is typically performed using massive multiple-input multiple-output (MIMO) antenna arrays. These massive MIMO arrays are composed of general-purpose TX and RX antenna elements that perform both DL TX and UL RX operations. To facilitate XDD operations, embodiments of the present disclosure introduce dedicated RX antenna elements to the massive MIMO antenna arrays. These dedicated RX antenna elements can be placed in proximity to the general-purpose TX and RX antenna elements in a variety of configurations. The resulting XDD massive MIMO antenna array is capable of operating in both TDD and XDD modes.

[0026] In the TDD mode, the general-purpose TX and RX antenna elements can perform both DL TX and UL RX operations, while the dedicated RX antenna elements either assist the UL RX operations or remain dormant. In the XDD mode, the general-purpose TX and RX antenna elements perform only DL TX operations in a first frequency allocation (i.e., a DL allocation), while the dedicated RX antenna elements simultaneously perform only UL RX operations in a second frequency allocation (i.e., an UL allocation). Both the UL allocation and the DL allocation are within the TDD band (e.g., the TDD band that the massive MIMO array is used for in the TDD mode).

[0027] Embodiments of the present disclosure also recognize that in XDD operations, UL signals are received at the BS in a frequency allocation (i.e., an UL allocation) that can be adjacent to a frequency allocation (i.e., a DL allocation) used to transmit DL signals. This is due to the fact that both the UL allocation and the DL allocation share the TDD band. The power amplifier (PA) used in the BS to generate the DL signals is not ideal and exhibits nonlinear behavior. This results in spillover of spectral energy outside the DL allocation into the UL allocation. This spillover energy is also referred to as transmitter (TX) leakage, which is primarily caused by PA nonlinearity. Even though the TX and RX processes can use separate antennas in a multiple-input multiple-output (MIMO) antenna array, due to antenna coupling, this spillover energy falls into the adjacent UL allocation. The DL TX leakage degrades the sensitivity of the UL receiver.

[0028] Embodiments of the present disclosure recognize that one solution to this problem is to physically separate the TX and RX antennas. When the TX and RX antennas are physically separated, sufficient isolation between the TX and RX signal chains can be obtained to reduce the DL TX leakage in the UL RX band to a degree that the sensitivity of the UL receiver is substantially unaffected. However, providing separation between the TX and RX antennas increases the size and weight of the BS to the extent that the TX-RX coupling is sufficiently low. In a massive MIMO TDD system, this is not practical. First, providing separate TX and RX antenna arrays doubles the size of the hardware system, which increases the cost of the BS and the cost of deployment (e.g., wind loading, etc.). Second, separate TX and RX antenna array arrangements violate the reciprocity of the DL and UL operation in TDD. Thus, this degrades the DL multi-user MIMO (MU-MIMO) performance.

[0029] Embodiments of the present disclosure recognize that another solution is to sample the DL TX signal at the transmitter and use the sample to generate a cancellation signal that can be used to cancel the TX leakage in the UL RX signal. Embodiments of the present disclosure recognize that another solution to the TX leakage problem is to perform the introduction of electromagnetic (EM) isolation hardware between the antennas of the TX and RX in XDD operation.

[0030] FIG. 1A An exemplary wireless system 100 operating in accordance with the principles of the present disclosure is shown. In the illustrated embodiment, the wireless system 100 includes a transmission point (e.g., an evolved Node B (eNB), a Node B), such as a base station (BS) 102. The BS 102 can communicate with other base stations as well as the Internet or a similar IP-based system (not shown). The BS 102 has an XDD massive MIMO antenna array 103. The BS 102 provides wireless cellular access (e.g., broadband access to the Internet) to user equipment (UE) 104 (e.g., a mobile phone, mobile station, or subscriber station) within a coverage area of the BS 102.

[0031] The UE 104 can access voice, data, video, video conferencing, and / or other broadband services via the Internet. The UE 104 can be associated with an access point (AP) of a WiFi WLAN. The UE 104 can be any of a number of mobile devices, including a wireless-enabled laptop computer, a wireless-enabled personal computer, a personal data assistant, a notebook, a handheld device, or other wireless-enabled device. While only one base station and one user equipment are depicted in the FIG. 1A It should be understood that the wireless system 100 can provide wireless broadband access to additional user equipment.

[0032] In this embodiment, wireless system 100 can operate using time division duplex (TDD) or frequency division duplex (FDD). In TDD operation (also referred to as TDD mode), there is one shared frequency band or channel that is allocated to both downlink (DL) communication and uplink (UL) communication. In FDD operation (also referred to as FDD mode), two separate portions of the frequency spectrum are allocated to DL and UL communication. Specifically, a DL frequency spectrum 106 (or DL allocation 106) is allocated to DL communication, while a UL frequency spectrum 108 (or UL allocation 108) is allocated to UL communication. Both DL frequency spectrum 106 and UL frequency spectrum 108 are within the same frequency band (i.e., a TDD frequency band) for TDD mode. From the perspective of a BS 102, DL communication is transmission of signals, while UL communication is reception of signals. From the perspective of a UE 104, DL communication is reception of signals, while UL communication is transmission of signals.

[0033] FIG. 1B An example spectrum diagram 105 is shown that illustrates an example of FDD mode operation performed by wireless system 100. FIG. 1A In this embodiment, DL frequency spectrum 106 and UL frequency spectrum 108 are adjacent to each other within a shared TDD frequency band 110. As a result, there is significant leakage of transmission (TX) power from DL frequency spectrum 106 to reception (RX) spectrum (UL frequency spectrum 108) because the transmission power of the transmission point is significantly higher than the reception power of the reception point. Moreover, the RX process of BS 102 is typically highly sensitive because it is designed to receive UL transmissions from mobile UEs that are in turn designed to operate efficiently relying on battery power, resulting in relatively low power UL signals that reach BS 102.

[0034] In some embodiments, a frequency gap (not shown) can be allocated between DL frequency spectrum 106 and UL frequency spectrum 108. This can be used to reduce TX leakage into the RX spectrum. In other embodiments, the allocated DL frequency spectrum 106 and UL frequency spectrum 108 can overlap. This can be the case, for example, in integrated access and backhaul (IAB) and full duplex systems.

[0035] In some embodiments, the size of DL frequency spectrum 106 and UL frequency spectrum 108 can be dynamically configured on each time slot 112. The configuration can be based on the amount of information that is ready to be transmitted in DL and UL during a given time slot 112. It is possible for a time slot 112 to be dedicated entirely to either DL frequency spectrum 106 or UL frequency spectrum 108.

[0036] Although FIG. 1A One example of wireless system 100 is shown, but various changes can be made to FIG. 1A wireless system 100. For example, wireless system 100 can include any number of UEs 104 and can be integrated with other BSs 102.

[0037] FIG. 2 An example BS 102 according to embodiments of the present disclosure is shown. FIG. 2 The illustrated embodiments of the BS 102 are for illustration only, and FIG. 1A The BSs 102 can have the same or similar configuration. However, BSs come in a wide variety of configurations, and FIG. 2 The scope of the present disclosure is not limited to any particular implementation of the BS.

[0038] As FIG. 2 As shown, the BS 102 includes multiple antennas 205a-205n and 206a-206n, multiple RF transceivers 210a-210n and 211a-211n, transmit (TX) processing circuitry 215, and receive (RX) processing circuitry 220. The BS 102 also includes a controller / processor 225, a memory 230, and a backhaul or network interface 235.

[0039] The multiple antennas 205a-205n and 206a-206n include the XDD massive MIMO antenna array 103. In some embodiments, the multiple antennas 205a-205n include a general purpose TX and RX antenna array for massive MIMO operation, and the multiple antennas 206a-206n include a dedicated RX antenna for UL RX operation. As described further below, the antennas 206a-206n can be arranged in a different location relative to the array of antennas 205a-205n. FIGS. 3A-8B The antennas 206a-206n can be arranged in a different location relative to the array of antennas 205a-205n, as described further below.

[0040] The general purpose TX and RX antennas 205a-205n can perform both DL TX operations and UL RX operations during TDD mode, and can perform DL TX operations during XDD mode. The dedicated RX antennas 206a-206n can perform UL RX operations only during XDD mode, or they can perform UL RX operations during both XDD mode and TDD mode. In the latter case, both the general purpose TX and RX antennas 205a-205n and the dedicated RX antennas 206a-206n perform UL RX operations during TDD mode.

[0041] The RF transceivers 210a-210n receive the incoming RF signals, such as signals transmitted by UE 104 or other UEs in the wireless system 100, from the antennas 205a-205n during TDD mode. Likewise, the RF transceivers 211a-211n receive such incoming RF signals from the antennas 206a-206n during XDD mode or TDD mode. The RF transceivers 210a-210n and 211a-211n down-convert the incoming RF signals to generate IF or baseband signals. The IF or baseband signals are sent to the RX processing circuitry 220, which generates processed baseband signals by filtering, decoding, and / or digitizing the baseband or IF signals. The RX processing circuitry 220 transmits the processed baseband signals to the controller / processor 225 for further processing.

[0042] The TX processing circuitry 215 receives analog or digital data (such as voice data, web data, e-mail, or interactive video game data) from the controller / processor 225. The TX processing circuitry 215 encodes, multiplexes, and / or digitizes the outgoing baseband data to generate processed baseband or IF signals. During both TDD mode and XDD mode, the RF transceivers 210a-210n receive the outgoing processed baseband or IF signals from the TX processing circuitry 215 and up-convert the baseband or IF signals to outgoing RF signals that are transmitted via the antennas 205a-205n.

[0043] The controller / processor 225 can include one or more processors or other processing devices to manage the overall operation of the BS 102. For example, the controller / processor 225 can control the reception of forward channel signals and the transmission of reverse channel signals by the RF transceivers 210a-210n, the RX processing circuitry 220, and the TX processing circuitry 215 in accordance with well-known principles. The controller / processor 225 can perform interference cancellation processes to isolate incoming RF signals from outgoing RF signals in XDD mode. In some embodiments, the interference cancellation processes are self-interference cancellation (SIC) processes.

[0044] In some embodiments, the RF transceivers 210a-210n or the RX processing circuitry 220 perform the interference cancellation processes. The interference cancellation processes can be implemented using special-purpose hardware (e.g., an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA)). The ASIC can be a radio-frequency ASIC (RF ASIC).

[0045] The controller / processor 225 may also support additional functions, such as more advanced wireless communication capabilities. For example, the controller / processor 225 may support beamforming or directional routing operations in which outgoing signals from multiple antennas 205a-205n are weighted differently to effectively direct the outgoing signals in a desired direction. The controller / processor 225 may support any of a variety of other functions in BS 102.

[0046] The controller / processor 225 is also capable of executing programs and other processes residing in the memory 230, such as the operating system (OS). The controller / processor 225 can move data into or out of the memory 230 as needed for the execution process.

[0047] The controller / processor 225 is also coupled to the backhaul or network interface 235. The backhaul or network interface 235 enables the BS 102 to communicate with other devices or systems via a backhaul connection or network. Interface 235 can support communication via any suitable wired or wireless connection. For example, when the BS 102 is implemented as part of a cellular communication system (such as a cellular communication system supporting 5G, LTE, or LTE-A), interface 235 can enable the BS 102 to communicate with other BSs via a wired or wireless backhaul connection. When the BS 102 is implemented as an access point, interface 235 can enable the BS 102 to communicate with a larger network (such as the Internet) via a wired or wireless local area network or via a wired or wireless connection. Interface 235 includes any suitable architecture that supports communication via wired or wireless connections, such as Ethernet or RF transceivers.

[0048] The memory 230 is coupled to the controller / processor 225. A portion of the memory 230 may include random access memory (RAM), while another portion of the memory 230 may include flash memory or other read-only memory (ROM).

[0049] although FIG. 2 An example of BS 102 is shown, but it is possible to modify it. FIG. 2 Various changes can be made. For example, BS 102 can include any number of FIG. 2 Each component shown. As a specific example, an access point may include multiple interfaces 235, and the controller / processor 225 may support routing functionality to route data between different network addresses. As another specific example, although shown as a single instance including TX processing circuitry 215 and a single instance including RX processing circuitry 220, BS 102 may include multiple instances of each (e.g., one per RF transceiver). Furthermore, FIG. 2 The various components can be combined, further subdivided, or omitted, and additional components can be added as needed.

[0050] With the development of communication technology, mobile data traffic volume increases, and accordingly, the bandwidth requirement for front-haul transmission between digital units and wireless units also greatly increases. In deployments such as a centralized / cloud radio access network (C-RAN), a BS includes a central unit (CU) and one or more distributed units (DUs).

[0051] A centralized unit (CU) can be connected with one or more DUs to provide higher layer functions than the DUs. For example, the CU can be responsible for radio resource control (RRC) and packet data convergence protocol (PDCP) layer functions, and the DUs and RUs can be responsible for lower layer functions. The DUs perform some functions of RLC (radio link control), MAC (media access control), and PHY (physical layer) (high PHY), and the RUs can be responsible for the remaining functions of the PHY layer (low PHY). Further, as an example, depending on the distributed arrangement implementation of the base station, digital units (DUs) can be included in the distributed units (DUs). Hereinafter, unless otherwise defined, the operation of the RF units as RUs is described. Embodiments of the present disclosure can be applied to arrangements that deploy at least one of CUs, DUs, or RUs, or arrangements that integrate CUs and DUs into one entity.

[0052] FIGS. 3A-8B Different embodiments of an example XDD massive MIMO antenna array 103 according to embodiments of the present disclosure are shown. In these embodiments, the XDD massive MIMO antenna array 103 can be implemented in a BS 102 of FIG. 1A and FIG. 2 . In particular, FIGS. 3A-8B Different arrangements of the physical layout of dedicated RX antennas 206a-206n with respect to the antennas 205a-205n, which include general TX and RX antenna arrays for massive MIMO operation, are shown, as described above with reference to FIG. 2 .

[0053] FIG. 3A A block diagram of an example XDD massive MIMO antenna array 103 according to embodiments of the present disclosure is shown. In this embodiment, dedicated RX antennas such as the antennas 206a-206n of FIG. 2 are placed below an existing antenna array of general TX and RX antennas such as the antennas 205a-205n of FIG. 2 . It should be understood that similar arrangements can be created in which the dedicated RX antennas are placed above or to the left or right of the existing antenna array of general TX and RX antennas shown. FIG. 3A

[0054] ​The antenna array 103 includes a plurality of general purpose TX and RX antennas 302 and 303, electromagnetic (EM) isolation hardware 304, and a plurality of dedicated RX antennas 305. The general purpose TX and RX antennas 302 and 303 form a general purpose TX and RX antenna array 301 for massive MIMO operation. During TDD mode, the general purpose TX and RX antennas 302 and 303 perform both DL TX operations and UL RX operations in different time slots. During XDD mode, the general purpose TX and RX antennas 302 and 303 perform only DL TX operations.

[0055] The dedicated RX antennas 305 perform UL RX operations during XDD mode. In some embodiments, the dedicated RX antennas 305 are not operational during TDD mode, while in other embodiments, the dedicated RX antennas 305 perform UL RX operations during TDD mode along with the general purpose TX and RX antennas 302 and 303. During XDD mode, the dedicated RX antennas 305 can perform UL RX operations in the same time slots that the general purpose TX and RX antennas 302 and 303 perform DL TX operations.

[0056] The EM isolation hardware 304 provides isolation between the general purpose TX and RX antenna array 301 and the dedicated RX antennas 305. This at least partially protects the dedicated RX antennas 305 from TX leakage from the general purpose TX and RX antennas 302 and 303 during XDD mode.

[0057] Since the general purpose TX and RX antennas 303 are the closest antennas in the array 301 to the dedicated RX antennas 305, they are considered the largest source of TX leakage during XDD mode. Accordingly, the DL TX signals input to the general purpose TX and RX antennas 303 can be coupled to a

[0058] Although FIG. 3A various changes can be made to the example XDD massive MIMO antenna array 103 shown. FIG. 3A For example, FIG. 3A various components in FIG. 3B may be combined, further subdivided, or omitted, and additional components can be added according to particular needs. FIG. 3A is a rotated three-dimensional view of a block diagram of an example XDD massive MIMO antenna array 103.

[0059] FIG. 3CA block diagram of an example XDD massive MIMO antenna array 103 according to embodiments of the disclosure is shown. This embodiment is similar to the FIG. 3A embodiment except for EM isolation hardware 304. In this embodiment, dedicated RX antennas such as FIG. 2 antennas 206a-206n are placed underneath an existing antenna array of general purpose TX and RX antennas such as FIG. 2 antennas 205a-205n. It should be understood that similar arrangements can be created where dedicated RX antennas are placed above or to the left or right of the existing antenna array of general purpose TX and RX antennas shown in FIG. 3C .

[0060] The antenna array 103 includes a plurality of general purpose TX and RX antennas 302 and 303 and a plurality of dedicated RX antennas 305. The general purpose TX and RX antennas 302 and 303 form a general purpose TX and RX antenna array 301 for massive MIMO operation. During TDD mode, the general purpose TX and RX antennas 302 and 303 perform both DL TX operations and UL RX operations in different time slots. During XDD mode, the general purpose TX and RX antennas 302 and 303 perform only DL TX operations.

[0061] The dedicated RX antennas 305 perform UL RX operations during XDD mode. In some embodiments, the dedicated RX antennas 305 are not operational during TDD mode, while in other embodiments, the dedicated RX antennas 305 perform UL RX operations during TDD mode along with the general purpose TX and RX antennas 302 and 303. During XDD mode, the dedicated RX antennas 305 can perform UL RX operations in the same time slots that the general purpose TX and RX antennas 302 and 303 perform DL TX operations.

[0062] Since the general purpose TX and RX antennas 303 are the closest antennas in the array 301 to the dedicated RX antennas 305, they are considered the largest source of TX leakage during XDD mode. Thus, the DL TX signals input to the general purpose TX and RX antennas 303 can be coupled to a

[0063] Although FIG. 3C one example of an XDD massive MIMO antenna array 103 is shown, various changes can be made to FIG. 3C . For example, FIG. 3C various components in FIG. 3C may be combined, further subdivided, or omitted, and additional components can be added in accordance with particular needs.FIG. 3D is FIG. 3C a rotated three-dimensional view of a block diagram of an example XDD massive MIMO antenna array 103.

[0064] FIG. 4A A block diagram of an example XDD massive MIMO antenna array 103 is shown, in accordance with an embodiment of the present disclosure. In this embodiment, dedicated RX antennas such as antennas 206a-206n are placed both above and below an existing antenna array of general purpose TX and RX antennas such as antennas 205a-205n. FIG. 2 FIG. 2

[0065] The antenna array 103 includes a plurality of general purpose TX and RX antennas 402 and 403, EM isolation hardware 404, and a plurality of dedicated RX antennas 405. The general purpose TX and RX antennas 402 and 403 form a general purpose TX and RX antenna array 401 for massive MIMO operation. During TDD mode, the general purpose TX and RX antennas 402 and 403 perform both DL TX operations and UL RX operations in different time slots. During XDD mode, the general purpose TX and RX antennas 402 and 403 perform only DL TX operations.

[0066] The dedicated RX antennas 405 perform UL RX operations during XDD mode. In some embodiments, the dedicated RX antennas 405 do not operate during TDD mode, while in other embodiments, the dedicated RX antennas 405 perform UL RX operations during TDD mode along with the general purpose TX and RX antennas 402 and 403. During XDD mode, the dedicated RX antennas 405 can perform UL RX operations in the same time slots that the general purpose TX and RX antennas 402 and 403 perform DL TX operations.

[0067] The EM isolation hardware 404 provides isolation between the general purpose TX and RX antenna array 401 and the dedicated RX antennas 405. This protects, at least in part, the dedicated RX antennas 405 from TX leakage from the general purpose TX and RX antennas 402 and 403 during XDD mode.

[0068] Since the general purpose TX and RX antennas 403 are the closest antennas in the array 401 to the dedicated RX antennas 405, they are considered the largest source of TX leakage during XDD mode. Therefore, the DL TX signals input to the general purpose TX and RX antennas 403 can be coupled to a interference cancellation process that uses the DL TX signals to generate a cancellation signal that, in turn, is used to cancel TX leakage caused by the general purpose TX and RX antennas 403 at the dedicated RX antennas 405.

[0069] Although​​FIG. 4A One example of an XDD massive MIMO antenna array 103 is shown, but various changes can be made FIG. 4A For example, FIG. 4A Various components in can be combined, further subdivided, or omitted, and additional components can be added in accordance with particular needs. FIG. 4B is a rotated three-dimensional view of a block diagram of an example XDD massive MIMO antenna array 103 of FIG. 4A

[0070] FIG. 5A A block diagram of an example XDD massive MIMO antenna array 103 is shown, in accordance with an embodiment of the present disclosure. In this embodiment, dedicated RX antennas of antennas 206a-206n, such as 206a, are placed on both the left and right sides of an existing antenna array of general purpose TX and RX antennas, such as antennas 205a-205n, 205a. FIG. 2 FIG. 2

[0071] The antenna array 103 includes a plurality of general purpose TX and RX antennas 502 and 503, EM isolation hardware 504, and a plurality of dedicated RX antennas 505. The general purpose TX and RX antennas 502 and 503 form a general purpose TX and RX antenna array 501 for massive MIMO operation. During TDD mode, the general purpose TX and RX antennas 502 and 503 perform both DL TX operations and UL RX operations in different time slots. During XDD mode, the general purpose TX and RX antennas 502 and 503 perform only DL TX operations.

[0072] The dedicated RX antennas 505 perform UL RX operations during XDD mode. In some embodiments, the dedicated RX antennas 505 are not operational during TDD mode, while in other embodiments, the dedicated RX antennas 505 perform UL RX operations during TDD mode along with the general purpose TX and RX antennas 502 and 503. During XDD mode, the dedicated RX antennas 505 can perform UL RX operations in the same time slots that the general purpose TX and RX antennas 502 and 503 perform DL TX operations.

[0073] The EM isolation hardware 504 provides isolation between the general purpose TX and RX antenna array 501 and the dedicated RX antennas 505. This at least partially protects the dedicated RX antennas 505 from TX leakage from the general purpose TX and RX antennas 502 and 503 during XDD mode.

[0074] ​​​Since the general TX and RX antenna 503 is the antenna in the array 501 closest to the dedicated RX antenna 505, it is considered the largest source of TX leakage during XDD mode. Thus, the DL TX signal input to the general TX and RX antenna 503 can be coupled to a cancelation process that uses the DL TX signal to generate a cancelation signal that in turn is used to cancel the TX leakage caused by the general TX and RX antenna 503 at the dedicated RX antenna 505.

[0075] Although FIG. 5A one example of an XDD massive MIMO antenna array 103 is shown, various changes can be made FIG. 5A For example, FIG. 5A various components in can be combined, further subdivided, or omitted and additional components can be added according to particular needs. FIG. 5B is FIG. 5A a rotated three-dimensional view of a block diagram of an example XDD massive MIMO antenna array 103.

[0076] FIG. 6A A block diagram of an example XDD massive MIMO antenna array 103 is shown, in accordance with an embodiment of the present disclosure. In this embodiment, dedicated RX antennas such as antennas 206a-206n are placed at the corners of an existing antenna array of general TX and RX antennas such as antennas 205a-205n. FIG. 2 FIG. 2

[0077] The antenna array 103 includes a plurality of general TX and RX antennas 602 and 603 and a plurality of dedicated RX antennas 605. The general TX and RX antennas 602 and 603 form a general TX and RX antenna array 601 for massive MIMO operation. During TDD mode, the general TX and RX antennas 602 and 603 perform both DL TX operations and UL RX operations in different time slots. During XDD mode, the general TX and RX antennas 602 and 603 perform only DL TX operations.

[0078] The dedicated RX antennas 605 perform UL RX operations during XDD mode. In some embodiments, the dedicated RX antennas 605 are not operational during TDD mode, while in other embodiments, the dedicated RX antennas 605 perform UL RX operations during TDD mode along with the general TX and RX antennas 602 and 603. During XDD mode, the dedicated RX antennas 605 can perform UL RX operations in the same time slots that the general TX and RX antennas 602 and 603 perform DL TX operations.

[0079] ​​Since the general TX and RX antenna 603 is the antenna in the array 601 closest to the dedicated RX antenna 605, it is considered the largest source of TX leakage during XDD mode. Therefore, the DL TX signal input to the general TX and RX antenna 603 can be coupled to an interference cancellation process that uses the DL TX signal to generate a cancellation signal that in turn is used to cancel the TX leakage caused by the general TX and RX antenna 603 at the dedicated RX antenna 605.

[0080] Additionally, each dedicated RX antenna 605 can have an antenna polarization in the same direction as the polarization angle of the closest general TX and RX antenna 603. This provides additional isolation between the dedicated RX antenna 605 and the general TX and RX antenna 603.

[0081] Although FIG. 6A one example of an XDD massive MIMO antenna array 103 is shown, various changes can be made FIG. 6A For example, FIG. 6A various components in FIG. 6B may be combined, further subdivided, or omitted, and additional components can be added in accordance with particular needs. FIG. 6A is a rotated three-dimensional view of a block diagram of an example XDD massive MIMO antenna array 103.

[0082] FIG. 7A shows a block diagram of an example XDD massive MIMO antenna array 103, in accordance with an embodiment of the present disclosure. In this embodiment, dedicated RX antennas such as antennas 206a-206n are placed on all four sides of an existing antenna array of general TX and RX antennas such as antennas 205a-205n. FIG. 2 FIG. 2

[0083] The antenna array 103 includes a plurality of general TX and RX antennas 702 and 703, EM isolation hardware 704, and a plurality of dedicated RX antennas 705. The general TX and RX antennas 702 and 703 form a general TX and RX antenna array 701 for massive MIMO operation. During TDD mode, the general TX and RX antennas 702 and 703 perform both DL TX operations and UL RX operations in different time slots. During XDD mode, the general TX and RX antennas 702 and 703 perform only DL TX operations.

[0084] ​​The dedicated RX antennas 705 perform UL RX operations during XDD mode. In some embodiments, the dedicated RX antennas 705 do not operate during TDD mode, while in other embodiments, the dedicated RX antennas 705 perform UL RX operations during TDD mode along with the general purpose TX and RX antennas 702 and 703. During XDD mode, the dedicated RX antennas 705 can perform UL RX operations in the same time slots that the general purpose TX and RX antennas 702 and 703 perform DL TX operations.

[0085] The EM isolation hardware 704 provides isolation between the general purpose TX and RX antenna array 701 and the dedicated RX antennas 705. This protects the dedicated RX antennas 705 at least in part from TX leakage from the general purpose TX and RX antennas 702 and 703 during XDD mode.

[0086] Since the general purpose TX and RX antenna 703 is the closest antenna in the array 701 to the dedicated RX antennas 705, it is considered the largest source of TX leakage during XDD mode. Therefore, the DL TX signals input to the general purpose TX and RX antenna 703 can be coupled to a cancellation process that uses the DL TX signals to generate a cancellation signal that in turn is used to cancel TX leakage caused by the general purpose TX and RX antenna 703 at the dedicated RX antennas 705.

[0087] Additionally, each dedicated RX antenna 705 can have an antenna polarization in the same direction as the polarization angle of the closest general purpose TX and RX antenna 703. This provides additional isolation between the dedicated RX antennas 705 and the general purpose TX and RX antennas 703.

[0088] Although FIG. 7A various changes can be made to the example XDD massive MIMO antenna array 103 shown. For example, FIG. 7A various components in FIG. 7A may be combined, further subdivided, or omitted, and additional components can be added according to particular needs. FIG. 7B is FIG. 7A a rotated three-dimensional view of the block diagram of the example XDD massive MIMO antenna array 103.

[0089] FIG. 8A shows a block diagram of an example XDD massive MIMO antenna array 103 according to embodiments of the present disclosure. In this embodiment, dedicated RX antennas such as the antennas 206a-206n of FIG. 2 are arranged in a pattern such as the pattern 208 of FIG. 2The common TX and RX antennas are arranged in a 2x1 subarray configuration above and below the existing antenna array of the common TX and RX antennas 205a-205n, and the common TX and RX antennas are also arranged in a 2x1 subarray configuration. It should be understood that this is one example, and other subarray configurations can be used. The antennas in the subarray configuration output the same received signal and are provided the same transmitted signal as input.

[0090] The antenna array 103 includes a plurality of common TX and RX antenna subarrays 802 and 803, EM isolation hardware 804, and a plurality of dedicated RX antenna subarrays 805. The common TX and RX antenna subarrays 802 and 803 form an array 801 of common TX and RX antenna subarrays for massive MIMO operation. During TDD mode, the common TX and RX antenna subarrays 802 and 803 perform both DL TX operations and UL RX operations in different time slots. During XDD mode, the common TX and RX antenna subarrays 802 and 803 perform only DL TX operations.

[0091] The dedicated RX antenna subarrays 805 perform UL RX operations during XDD mode. In some embodiments, the dedicated RX antenna subarrays 805 are not operational during TDD mode, while in other embodiments, the dedicated RX antenna subarrays 805 perform UL RX operations during TDD mode along with the common TX and RX antenna subarrays 802 and 803. During XDD mode, the dedicated RX antenna subarrays 805 can perform UL RX operations in the same time slots that the common TX and RX antenna subarrays 802 and 803 perform DL TX operations.

[0092] The EM isolation hardware 804 provides isolation between the array 801 of common TX and RX antenna subarrays and the dedicated RX antenna subarrays 805. This protects, at least in part, the dedicated RX antenna subarrays 805 from TX leakage from the common TX and RX antenna subarrays 802 and 803 during XDD mode.

[0093] Since the common TX and RX antenna subarray 803 is the closest antenna subarray in the array 801 to the RX antenna subarrays 805, it is considered the largest source of TX leakage during XDD mode. Accordingly, the DL TX signals input to the common TX and RX antenna subarray 803 can be coupled to a interference cancellation process that uses the DL TX signals to generate a cancellation signal that, in turn, is used to cancel TX leakage caused by the common TX and RX antenna subarray 803 at the dedicated RX antenna subarrays 805.

[0094] Although FIG. 8AAn example of an XDD massive MIMO antenna array 103 is shown, but more can be found in other examples. FIG. 8A Make various changes. For example, FIG. 8A The various components can be combined, further subdivided, or omitted, and additional components can be added as needed. FIG. 8B yes FIG. 8A A rotated 3D view of the block diagram of the example XDD massive MIMO antenna array 103.

[0095] FIG. 9A A block diagram of an example XDD operation 900 according to an embodiment of the present disclosure is shown. In some embodiments, the XDD operation 900 may be as shown in FIG1 to FIG1. FIG. 2 BS 102 execution. It can be used... FIGS. 3A-8B Any XDD massive MIMO antenna array 103 to perform XDD operation 900. FIG. 9B It shows in FIG. 9A Example spectrum diagrams 910-913 of the signal at different points in the XDD operation 900.

[0096] Example XDD operation 900 includes a signal processing unit 901, a TX analog signal chain 902, a coupler 903, a TX / RX switch 904, a general-purpose TX and RX antenna 905, a dedicated RX antenna 906, and three RX analog signal chains: RX analog signal chain 907, RX analog signal chain 908, and RX analog signal chain 909. The general-purpose TX and RX antenna 905 and the dedicated RX antenna 906 are... FIGS. 1A-8B It is part of the XDD massive MIMO array 103.

[0097] Signal processing unit 901 includes TX and RX processing chains and an interference cancellation process. In some embodiments, the interference cancellation process may be a SIC process. The interference cancellation process may be referred to as a TX leakage cancellation process because TX leakage is the target of cancellation in this embodiment. In some embodiments, signal processing unit 901 is implemented in controller / processor 225 of BS 102, or in RF transceiver 210a-210n or RX processing circuitry 220 of BS 102.

[0098] The TX analog signal chain 902 receives signal TX1 from signal processing unit 901 and generates a TX signal (TX1_out) for output from the general-purpose TX and RX antenna 905 based on TX1. The TX analog signal chain 902 may include components such as a power amplifier (PA) and any other suitable components for generating the RF output signal. The TX analog signal chain 902 may be implemented in part in each of the TX processing circuitry 215 and the RF transceivers 210a-210n.

[0099] PA is nonlinear, it generates a TX leakage signal in the frequency allocation adjacent to the DL TX frequency allocation. This is illustrated in the spectral plots 910 and 911, which represent the spectrum of the input and output of the TX signal chain 902, respectively. As shown, a TX leakage 914 is introduced into the output of the TX signal chain 902. In TDD mode, since the BS 102 does not use the frequency allocation adjacent to the DL TX frequency allocation, it can not be concerned with this TX leakage. However, in XDD mode, the frequency allocation adjacent to the DL TX frequency allocation can correspond to the UL RX frequency allocation, in which case the TX leakage interferes with the UL RX signal corresponding to the signal RX2, as described below. FIG. 9B

[0100] The coupler 903 samples a small portion of the signal TX1_out output from the TX analog signal chain 902 and inputs it to the RX analog signal chain 909. The sampled signal output by the coupler 903 can be referred to as a sense signal of the TX1_out signal. The RX analog signal chain 909, in turn, performs any analog processing and signal conditioning required before outputting a signal RX_aux to the signal processing unit 901 for generating an interference cancellation signal. As shown in the spectral plot 912, RX_aux is a replica of TX1_out at a lower power. As described below, the interference cancellation signal is combined with the RX2 signal to cancel the TX leakage caused by the TX1_out signal in the RX2 signal in XDD mode. FIG. 9B

[0101] After the sampling to form the RX_aux signal, the TX / RX switch 904 receives the remaining power of the TX1_out signal from the coupler 903. In some embodiments, the coupler 903 samples about 1% of the total power of the TX1_out signal, while the remaining 99% of the power of the TX1_out signal is passed to the TX / RX switch 904. In TDD mode, the TX / RX switch 904 switches as needed to connect the common TX and RX antenna 905 with one of the TX signal chain 902 or the RX signal chain 907. More specifically, in TDD mode, during the DL TX time slots, the TX / RX switch 904 connects the TX analog signal chain 902 with the common TX and RX antenna 905, and in TDD mode, during the UL RX time slots, the TX / RX switch 904 connects the common TX and RX antenna 905 with the RX analog signal chain 908. In XDD mode, since the common TX and RX antenna 905 is only used for transmission in XDD mode, the TX / RX switch 904 only connects the common TX and RX antenna 905 with the TX analog signal chain 902.

[0102] ​​The common TX and RX antennas 905 are used for massive MIMO operation. For example, the common TX and RX antennas 905 can be FIG. 2 one of the antennas 205a-205n of the BS 102, and can be one of the common TX and RX antennas or antenna elements 305, 405, 505, 605, 705, or 805 of the array 301, 401, 501, 601, 701, or 801. In this embodiment, one antenna is shown with one polarization, but it should be understood that this is for illustrative purposes only, and the XDD operation 900 can include any number of common TX and RX antennas 905 and corresponding TX chain and RX chain components 902, 903, 904, 908, and 909. FIGS. 3A-8B

[0103] In XDD mode, the common TX and RX antennas 905 receive the TX1_out signal from the TX / RX switch 904 and radiate the TX1_out signal. Although the intended recipient of the TX1_out signal is, for example, the UE 104, the TX1_out signal will also leak into the dedicated RX antennas 906 via over-the-air coupling. FIG. 1A

[0104] The dedicated RX antennas 906 can be, for example, one of the antennas 206a-206n of the BS 102, and can be one of the dedicated RX antennas or antenna elements 305, 405, 505, 605, 705, or 805 of the array 301, 401, 501, 601, 701, or 801. In this embodiment, one antenna is shown with the same angle of polarization as the common TX and RX antennas 905. It should be understood that this is for illustrative purposes only, and the XDD operation 900 can include any number of dedicated RX antennas 906 and corresponding RX chain components 907. FIG. 2 FIGS. 3A-8B As described above, the RX analog signal chain 907 receives the UL RX signal from the dedicated RX antennas 906 and performs any required analog processing and signal conditioning before outputting the signal RX2 to the signal processing unit 901, which can contain the RX processing chain. As described above, the UL RX signal includes interference caused by TX leakage of the DL TX signal TX1_out. This is illustrated in the spectrum diagram 913, which shows that the TX leakage 914 is in the same frequency allocation as the desired UL RX signal 915. In this embodiment, the DL TX signal component, including the TX leakage 914, is partially attenuated in the UL RX signal due to antenna isolation (e.g., due to physical spacing or due to isolation of EM isolation hardware).

[0105] As described above, the RX analog signal chain 907 receives the UL RX signal from the dedicated RX antennas 906 and performs any required analog processing and signal conditioning before outputting the signal RX2 to the signal processing unit 901, which can contain the RX processing chain. As described above, the UL RX signal includes interference caused by TX leakage of the DL TX signal TX1_out. This is illustrated in the spectrum diagram 913, which shows that the TX leakage 914 is in the same frequency allocation as the desired UL RX signal 915. In this embodiment, the DL TX signal component, including the TX leakage 914, is partially attenuated in the UL RX signal due to antenna isolation (e.g., due to physical spacing or due to isolation of EM isolation hardware). FIG. 9B

[0106] ​​​​In some embodiments, the signal processing unit 901 uses the RX aux signal to generate a cancellation signal that is applied to the RX2 signal to reduce or completely cancel the TX leakage in the RX2 signal. In other embodiments, EM isolation hardware, such as the EM isolation hardware 304, 404, 504, 704, or 804, is placed between the general purpose TX and RX antennas 905 and the dedicated RX antennas 906 to reduce the amount of TX leakage contained in RX2. In other embodiments, the physical spacing between the general purpose TX and RX antennas 905 and the dedicated RX antennas 906 within the XDD massive MIMO antenna array 103 reduces the amount of TX leakage contained in RX2. Any of these embodiments can be combined with each other to reduce the TX leakage below the RX noise floor so that the RX process is not affected by the TX leakage.

[0107] Although FIG. 9A one example of XDD operation 900 is shown, various changes can be made FIG. 9A For example, FIG. 9A Various components in may be combined, further subdivided, or omitted, and additional components can be added in accordance with particular needs.

[0108] FIG. 10 An example time-frequency diagram 1000 of TDD and XDD patterns for a BS according to embodiments of the disclosure is shown. In some embodiments, the time- frequency diagram 1000 represents the TDD and XDD patterns performed by the BS 102 of FIGS. 1A-2 The TDD and XDD patterns can be performed using any XDD massive MIMO antenna array 103 of FIGS. 3A-8B The XDD patterns can be performed as disclosed above with respect to the XDD operation 900 of FIGS. 9A-10

[0109] In the TDD pattern, in the TDD DL slot, a physical downlink shared channel (PDSCH) 1001 is transmitted with up to full-band frequency allocation of the TDD band 110 and with MU-MIMO capability. The PDSCH 1001 is transmitted by the general purpose TX and RX antennas of the XDD massive MIMO antenna array 103. These antennas can be, for example, the antennas 205a-205n of the BS 102 in FIG. 11 as shown by the general purpose TX and RX antennas 905 in FIG. 9A and can be part of the general purpose TX and RX antennas or antenna element arrays (e.g., the array 301, 401, 501, 601, 701, or 801 in FIGS. 3A-8B

[0110] ​Next, in TDD mode, in a TDD UL slot, a Physical Uplink Shared Channel (PUSCH) 1002 is received with up to full-band frequency allocation of the TDD band 110. The PUSCH signal can be received by the general purpose TX and RX antennas and the dedicated RX antennas of the XDD massive MIMO antenna array 103. The dedicated RX antennas can be, for example FIG. 9A the antennas 206a-206n of the BS 102 in FIGS. 3A-8B as shown by the dedicated RX antennas 906 in FIGS. 8A-8B and can be part of the antennas or antenna elements 305, 405, 505, 605, 705, or 805 of In some embodiments, in TDD mode, only the general purpose TX and RX antennas receive the PUSCH, while the dedicated RX antennas are in a dormant state. Typically, a subset of the signals received by the multiple antennas is used for the PUSCH processing.

[0111] Next, still in TDD mode, the general purpose TX and RX antennas of the XDD massive MIMO antenna array 103 receive an UL Sounding Reference Signal (SRS) in a TDD UL slot. Again, the SRS is received with up to full-band frequency allocation of the TDD band 110. The UL SRS is used for TDD beamforming operations, and its reception by the general purpose TX and RX antennas enables UL-DL reciprocity to be used for beamforming of DL signals. That is, because the UL channel of the general purpose TX and RX antennas is essentially the same as its DL channel, the channel information obtained from the received UL SRS can be used for DL beamforming of DL signals transmitted by those same general purpose TX and RX antennas.

[0112] At time 1004 of the time-frequency diagram 1000, the system transitions to XDD mode. In XDD mode, UL reception of PUSCH 1005 and DL transmission of PDSCH 1006 occur simultaneously. The PUSCH 1005 is received by the dedicated RX antennas, and the PDSCH 1006 is transmitted by the general purpose TX and RX antennas. The DL transmission of PDSCH 1006 has a DL frequency allocation that is less than the entire TDD band 110 (e.g., the DL spectrum 106 of FIGS. 3A-5B to allow for uplink UL reception in nearby or adjacent frequency allocations (e.g., the UL spectrum 108 of FIGS. 7A-8B within the TDD band 110.

[0113] In this embodiment, the DL transmission of PDSCH 1006 in XDD mode can utilize MU-MIMO beamforming enabled by the reception of UL SRS 1003 in TDD mode. This is possible because PDSCH 1006 is transmitted in XDD mode by the same common TX and RX antennas that perform UL SRS 1003 in TDD mode, so UL-DL reciprocity is maintained at these antennas in XDD mode.

[0114] Although ​ One example time-frequency diagram 1000 is shown for TDD and XDD modes, but various changes can be made. ​ For example, additional signals can be transmitted or received, or signals can be omitted from ​ For example, additional signals can be transmitted or received, or signals can be omitted from

[0115] ​ Processes for operating RF units are shown in accordance with various embodiments of the present disclosure. For example, ​ The processes described in ​ may be performed by BS 102, and can use the XDD massive MIMO antenna array 103 of any of ​ and can include TDD and XDD mode operation as disclosed in ​

[0116] The RF units performing the processes of ​ include an antenna array, such as the XDD massive MIMO antenna array 103 of BS 102, which includes a plurality of antenna elements. A first set of antenna elements is, for example, the common TX and RX antennas 205a-205n of BS 102, as shown by the common TX and RX antennas 905 in ​ A first set of antenna elements can be arranged as a massive MIMO array, such as the array 301, 401, 501, 601, 701, or 801 of ​ A second set of antenna elements is, for example, the dedicated RX antennas 206a-206n of BS 102, as shown by the dedicated RX antennas 906 in ​

[0117] As shown by the antenna elements 305, 405, 505, 605, 705, or 805 of ​ In various configurations, the second set of antenna elements can be disposed near at least one edge of the massive MIMO array of the first set of antenna elements, as shown by the antenna elements 305, 405, 505, 605, 705, or 805 of ​ Some or all of the antenna elements of the RF unit can be arranged in a subarray configuration, as shown by the antenna elements 305, 405, 505, 605, 705, or 805 of ​ and​​​ EM isolation hardware 304, 404, 504, 704 or 804.

[0118] The RF unit is configured to operate in two modes. The first mode is TDD mode, and the second mode is XDD mode. A first set of antenna elements is configured to transmit and receive in the first mode, and transmit only in the second mode. A second set of antenna elements is configured to receive only in both modes. In some embodiments, the second set of antenna elements operates only in the second mode and remains dormant in the first mode.

[0119] In the second mode, the transmitted signal from the first set of antenna elements is transmitted in the first frequency allocation, while the received signal from the second set of antenna elements is received in the second frequency allocation. The first and second frequency allocations may overlap, be adjacent and non-overlapping, or non-overlapping with a band gap between them. In the second mode, the relative sizes of the first and second frequency allocations can dynamically change between time slots. In the first mode, both the transmitted signal from the first set of antenna elements and the received signal are allocated to a third frequency allocation, which may include both the first and second frequency allocations. The third frequency allocation may be a TDD band, and the first and second frequency allocations are subsets of the TDD band.

[0120] The process begins in the first mode by transmitting a first transmit signal and receiving a first receive signal via a first group of antenna elements in the antenna array of the RF unit (step 1105). The transmission and reception in step 1105 occur during a third frequency allocation. For example, in step 1105, general-purpose TX and RX antennas transmit and receive TDD DL and UL signals in the TDD band, respectively. The TDD DL signal may include, for example, PDSCH, and the TDD UL signal may include, for example, PUSCH or UL SRS. The first group of antennas transmits the TDD DL signal in the TDD DL time slot, while the first group of antennas receives the TDD UL signal in the TDD UL time slot.

[0121] In some embodiments, the process continues by receiving the first received signal via a second set of antenna elements of a plurality of antenna elements in the antenna array of the RF unit in the first mode (step 1110). The reception in step 1110 occurs in a third frequency allocation. For example, in step 1110, a dedicated RX antenna receives a TDD UL signal in the TDD band. The TDD UL signal received by the second set of antennas may include, for example, PUSCH. The reception of the TDD UL signal by the second set of antennas in TDD mode occurs within the TDD UL time slot.

[0122] The process continues by transmitting a second transmit signal via a first set of the plurality of antenna elements in the second mode (step 1115). The transmission of step 1115 occurs in the first frequency allocation. For example, in step 1115, the common TX and RX antennas transmit an XDD DL signal in a subset of the TDD frequency band corresponding to the DL allocation. The XDD DL signal can include, for example, a PDSCH. The XDD DL signal can be a beamformed signal that is beamformed using the UL SRS received in step 1105. This is possible because by using the common TX and RX antennas for UL reception of the UL SRS in the TDD mode and for DL transmission in the XDD mode, UL-DL reciprocity is maintained between the TDD and XDD modes.

[0123] The process continues by receiving a second receive signal via a second set of the plurality of antenna elements in the second mode (step 1120). The reception of step 1120 occurs in the second frequency allocation. For example, in step 1120, the dedicated RX antennas receive an XDD UL signal in a subset of the TDD frequency band corresponding to the UL allocation. The XDD UL signal can include, for example, a PUSCH.

[0124] Steps 1115 and 1120 occur in the same one or more time slots. For example, steps 1115 and 1120 occur during an XDD time slot. This is achieved by using different frequency allocations for the XDD DL transmission and the XDD UL reception. As mentioned above, due to the simultaneous transmission of the XDD DL signal, some interference can appear in the received XDD UL signal. This interference can be reduced by the physical separation of the first set of antenna elements and the second set of antenna elements, by EM isolation hardware disposed between the first set of antenna elements and the second set of antenna elements, by interference cancellation processing based on sensing the XDD DL signal, or by a combination thereof.

[0125] According to various embodiments, a radio frequency (RF) unit includes an antenna array including a plurality of antenna elements. A first set of the plurality of antenna elements is configured to operate in a first mode, and a second set of the plurality of antenna elements is configured to operate in a second mode. In the first mode, the first set of the plurality of antenna elements is configured to transmit and receive, and in the second mode, the second set of the plurality of antenna elements is configured to receive only.

[0126] In some embodiments, the second set of the plurality of antenna elements is also configured to operate in the first mode, and in the first mode, the second set of the plurality of antenna elements is configured to receive only.

[0127] In some embodiments, the first set of antenna elements of the plurality of antenna elements are further configured to operate in a second mode in which the first set of antenna elements of the plurality of antenna elements are configured to only transmit and in which the second set of antenna elements of the plurality of antenna elements are configured to receive in the same time slots as the first set of antenna elements of the plurality of antenna elements transmit.

[0128] In some embodiments, in the second mode, the first set of antenna elements of the plurality of antenna elements are configured to transmit in a first frequency allocation, in the second mode, the second set of antenna elements of the plurality of antenna elements are configured to receive in a second frequency allocation, and the first frequency allocation and the second frequency allocation either overlap or do not overlap.

[0129] In some embodiments, the first frequency allocation and the second frequency allocation comprise a third frequency allocation, and in the first mode, the first set of antenna elements of the plurality of antenna elements are configured to transmit and receive in the third frequency allocation.

[0130] In some embodiments, a size of the first frequency allocation and a size of the second frequency allocation are dynamic between time slots.

[0131] In some embodiments, the first set of antenna elements of the plurality of antenna elements are further configured to: in the first mode, receive a sounding reference signal (SRS) in a first time slot, and in the second mode, transmit a beamformed signal based on the received SRS in a second time slot.

[0132] In some embodiments, at least some of the plurality of antenna elements comprise a plurality of antennas arranged in a subarray configuration.

[0133] In some embodiments, the first set of antenna elements of the plurality of antenna elements comprise a massive multiple-input multiple-output (MIMO) array, and antenna elements comprising the second set of antenna elements of the plurality of antenna elements are disposed adjacent to at least one edge of the massive MIMO array.

[0134] In some embodiments, the RF unit further comprises an electromagnetic (EM) isolation element disposed between the first set of antenna elements of the plurality of antenna elements and the second set of antenna elements of the plurality of antenna elements.

[0135] According to various embodiments, a method of operating a radio frequency (RF) unit, comprising: in a first mode, transmitting a first transmit signal and receiving a first receive signal via a first set of antenna elements of a plurality of antenna elements of an antenna array of the RF unit; and in a second mode, receiving a second receive signal via a second set of antenna elements of the plurality of antenna elements of the antenna array of the RF unit.

[0136] In some embodiments, the method further includes receiving, in the first mode, at least some of the first receive signals via a second set of the plurality of antenna elements.

[0137] In some embodiments, the method further includes transmitting, in the second mode, the second transmit signals via a first set of the plurality of antenna elements, and receiving, in the second mode, the second receive signals via a second set of the plurality of antenna elements in the same time slots that the first set of the plurality of antenna elements transmits the second transmit signals.

[0138] In some embodiments, the method further includes transmitting, in the second mode, the second transmit signals via a first set of the plurality of antenna elements in a first frequency allocation, and receiving, in the second mode, the second receive signals via a second set of the plurality of antenna elements in a second frequency allocation. The first and second frequency allocations either overlap or do not overlap.

[0139] In some embodiments, wherein the first and second frequency allocations include a third frequency allocation, the method further includes, in the first mode, transmitting the first transmit signals and receiving the first receive signals via a first set of the plurality of antenna elements in the third frequency allocation.

[0140] In some embodiments, a size of the first frequency allocation and a size of the second frequency allocation are dynamic between time slots.

[0141] In some embodiments, the method further includes, in the first mode, receiving, via a first set of the plurality of antenna elements, a sounding reference signal (SRS) in a first time slot, and in the second mode, transmitting, via the first set of the plurality of antenna elements, a beamformed signal based on the received SRS in a second time slot.

[0142] In some embodiments, at least some of the plurality of antenna elements include a plurality of antennas arranged in a subarray configuration.

[0143] In some embodiments, the first set of the plurality of antenna elements includes a massive multiple-input multiple-output (MIMO) array, and an antenna element of the second set of the plurality of antenna elements is disposed adjacent to at least one edge of the massive MIMO array in the RF unit.

[0144] In some embodiments, an electromagnetic (EM) isolation element is disposed between the first set of the plurality of antenna elements and the second set of the plurality of antenna elements in the RF unit.

[0145] The flow diagrams illustrate the example methods that can be implemented in accordance with the principles of the present disclosure and that the operations in the flow diagrams can be rearranged, omitted, or supplemented with other operations in accordance with the principles of the present disclosure. For example, although the operations are shown as a series of steps, various steps could overlap, occur in parallel, or occur in a different order. In another example, steps can be omitted or replaced by other steps.

[0146] While the present disclosure has been described with respect to exemplary embodiments, those skilled in the art will recognize that various changes and modifications can be made hereto. It is therefore intended to cover all such changes and modifications that fall within the scope of the appended claims. None of the description in this application should be read in any manner which would utilize any element, step, or function to the exclusion of other elements, steps, or functions described herein. The patentable scope of the present subject matter is defined by the claims and can include other elements, steps, or functions.

Claims

1. A radio frequency, RF, unit, the RF unit comprising: an antenna array comprising a plurality of antenna elements, wherein, a first group of antenna elements of the plurality of antenna elements is configured to operate in a first mode corresponding to time division duplex, TDD, and a second mode corresponding to cross division duplex, XDD, and a second group of antenna elements of the plurality of antenna elements is configured to operate in the second mode, wherein, in the first mode, the first group of antenna elements of the plurality of antenna elements is configured to transmit signals and receive signals, wherein, in the second mode, the first group of antenna elements of the plurality of antenna elements is configured to transmit first signals and the second group of antenna elements of the plurality of antenna elements is configured to receive second signals, and wherein, the second group of antenna elements of the plurality of antenna elements is dedicated to receive the second signals in the second mode.

2. The RF unit of claim 1, the RF unit further comprising: an RF circuit electrically connected to the first group of antenna elements and the second group of antenna elements of the plurality of antenna elements, wherein, the RF circuit is configured to: identify the first signals transmitted in the second mode via the first group of antenna elements of the plurality of antenna elements, generate signals for cancelling interference caused by the first signals, and combine the signals for cancelling the interference with the second signals.

3. The RF unit of claim 1, wherein, in the second mode, the second group of antenna elements of the plurality of antenna elements is configured to receive the second signals in the same time slots in which the first group of antenna elements of the plurality of antenna elements transmits the first signals.

4. The RF unit of claim 1, wherein, in the second mode, the first group of antenna elements of the plurality of antenna elements is configured to transmit the first signals in a first sub-band within a TDD frequency band, wherein, in the second mode, the second group of antenna elements of the plurality of antenna elements is configured to receive the second signals in a second sub-band within the TDD frequency band, and wherein, the first sub-band and the second sub-band either overlap or do not overlap.

5. The RF unit of claim 4, wherein, in the first mode, the TDD frequency band comprising the first sub-band and the second sub-band is selectively allocated to the first group of antenna elements or the second group of antenna elements of the plurality of antenna elements.

6. The RF unit of claim 4, wherein, a size of the first sub-band and a size of the second sub-band are varied for each time slot.

7. The RF unit of claim 1, wherein, the first group of antenna elements of the plurality of antenna elements is further configured to: in the first mode, receive a sounding reference signal, SRS, in a first time slot, and in the second mode, transmit the first signals beamformed based on the received SRS in a second time slot.

8. The RF unit of claim 1, wherein, at least some of the plurality of antenna elements are configured as sub-arrays.

9. The RF unit of claim 1, wherein, The first group of the plurality of antenna elements comprises a massive multiple-input multiple-output (MIMO) array, and wherein the second group of the plurality of antenna elements is disposed adjacent to at least one edge of the massive MIMO array.

10. The RF unit of claim 1, further comprising: an electromagnetic (EM) isolation element disposed between the first group of the plurality of antenna elements and the second group of the plurality of antenna elements.

11. A method performed by a radio frequency (RF) unit, the method comprising: transmitting and receiving signals via a first group of a plurality of antenna elements of an antenna array of the RF unit if the antenna array of the RF unit is operated in a first mode corresponding to time division duplex (TDD); and if the antenna array of the RF unit is operated in a second mode corresponding to frequency division duplex (FDD): transmitting a first signal via the first group of the plurality of antenna elements; and receiving a second signal via a second group of the plurality of antenna elements of the antenna array, wherein the first group of the plurality of antenna elements is configured to operate in the first mode and the second mode, and wherein the second group of the plurality of antenna elements is configured to operate in the second mode and is dedicated to receive the second signal in the second mode.

12. The method of claim 11, further comprising: identifying, using RF circuitry, the first signal transmitted via the first group of the plurality of antenna elements in the second mode, generating a signal to cancel interference caused by the first signal, and combining the signal to cancel the interference with the second signal.

13. The method of claim 12, wherein, the RF circuitry comprises: circuitry to process the first signal and the second signal, a first RF path to electrically connect the circuitry and the first group of the plurality of antenna elements, a coupler to obtain the first signal from the first RF path, a second RF path to electrically connect the circuitry and the coupler, and a third RF path to electrically connect the circuitry and the second group of the plurality of antenna elements.

14. The method of claim 11, further comprising: transmitting, in the second mode, the first signal via the first group of the plurality of antenna elements in a first sub-band within a TDD frequency band; and receiving, in the second mode, the second signal via the second group of the plurality of antenna elements in a second sub-band within the TDD frequency band, wherein the first sub-band and the second sub-band either overlap or do not overlap, and wherein, in the second mode, the first signal is transmitted in a time slot and the second signal is received in the time slot.

15. The method of claim 14, wherein, In the first mode, the TDD frequency band, including the first sub-band and the second sub-band, is selectively allocated to the first set of antenna elements or the second set of antenna elements of the plurality of antenna elements.

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