Method and apparatus for determining beam interference

Abstract

An apparatus, comprising: a MIMO antenna for transmitting beamformed signals on multiple beams using physical channel resources limited by a common frequency and time; a component for calculating the beamforming gain of each beam in each sub-sector in the coverage area of the multiple beams; a component for determining the beam dominant area of each beam within the coverage area of the multiple beams; a component for determining, within the dominant area of each beam, the average value of the beamforming gains of each other beam that is at least partially co-located within the beam dominant area; a component for determining the inter-beam interference estimate as the average interference of each beam from each of the other beams; and a component for scheduling the transmission of beams by the MIMO antenna on the physical channel resources limited by the common frequency and time based on the inter-beam interference estimate.

Description

Technical Field

[0001] The present invention relates to determining interference between beams. Background Art

[0002] Current and future wireless communication systems, such as Long-Term Evolution (LTE) or fifth generation (5G), also known as New Radio (NR), have been envisioned to use multiple-input multiple-output (MIMO) multi-antenna transmission techniques. The increasing requirements for high throughput have prompted wireless communication systems such as 5G to use mmWave (millimeter wave) frequencies - due to the available high bandwidth.

[0003] However, the use of mmWave frequencies poses new challenges to MIMO performance. By applying amplitude and phase precoding / beamforming weights (i.e., beam weights), signals are transmitted in the desired direction from all elements in the antenna array, thereby enabling beamformed data transmission. Beamformed transmission from a large antenna array in massive MIMO from a network element such as a base station (e.g., gNodeB (gNb)) provides improved signal strength to a desired user equipment (UE), but may cause significant interference to other UEs if the beam generates unwanted interference in the direction of other UEs.

[0004] Multiple users can be simultaneously scheduled on frequency-time resources in multi-user MIMO (MU-MIMO), while transmitting beamformed signals in the dominant direction of the users. MU-MIMO improves system throughput by co-scheduling multiple UEs in the same physical resource block (PRB) in the same time slot. The advantages of MU-MIMO can be achieved only when the beamformed transmission towards one UE does not cause too much interference to other co-scheduled UEs.

[0005] Therefore, MU-MIMO transmission is subject to strong co-channel interference, which is not the case for single-user MIMO (SU-MIMO). However, the currently used interference management methods are more suitable for SU-MIMO rather than MU-MIMO. Summary of the Invention

[0006] Now, an improved method and a technical device for implementing the method have been invented, thus solving the above problems. Various aspects include a method, an apparatus, and a non-transitory computer-readable medium including a computer program or a signal stored therein, characterized by what is stated in the independent claims. Various details of the embodiments are disclosed in the dependent claims and the corresponding drawings and description.

[0007] The scope of protection sought by the various embodiments of the present invention is defined by the independent claims. Embodiments and features (if any) described in this specification that do not fall within the scope of the independent claims will be construed as examples that help to understand the various embodiments of the present invention.

[0008] According to a first aspect, there is provided an apparatus, comprising: a multiple-input multiple-output (MIMO) antenna for transmitting beamformed signals on multiple beams using physical channel resources limited by a common frequency and time; means for calculating the beamforming gain of each beam in each sub-sector in the coverage area of the multiple beams; means for determining the beam dominant area of each beam within the coverage area of the multiple beams; means for determining, within the dominant area of each beam, the average value of the beamforming gains of each other beam that is at least partially co-located within the beam dominant area; means for determining the inter-beam interference estimate as the average interference of each beam from each of the other beams; and means for scheduling the transmission of beams by the MIMO antenna on the physical channel resources limited by the common frequency and time based on the inter-beam interference estimate.

[0009] According to one embodiment, the apparatus comprises means for storing in a two-dimensional table the values of the average interference of each beam from each of the other beam values.

[0010] According to one embodiment, a sub-sector is defined as a range of azimuth and elevation angles.

[0011] According to one embodiment, the apparatus comprises means for calculating the beamforming gain of beam i, the beam weight vector of beam i being given by an n TRX / 2×1 length weight vector b i The beamforming gain of beam i is calculated as:

[0012] B i (θ, φ) = ||H θ,φ b i || 2

[0013] where H θ,φ is a 1×n TRX / 2 steering vector in the (θ, φ) direction, and n TRX is the number of transmit-receive units (TRXs) of the transmitter.

[0014] According to one embodiment, the apparatus comprises means for determining the beam dominant area of each beam i as the following formula:

[0015]

[0016] where R is a set of all (θ, φ) angle pairs according to a predefined quantization strategy and within a coverage area of interest, and B x (θ, φ) is the beamforming gain of beam x at azimuth and elevation angles θ and respectively.

[0017] According to one embodiment, the apparatus is for calculating the average interference from beam b j to b i using the following formula:

[0018]

[0019] where |BDR i | is the cardinality of set BDR i or the number of entries in set BDR i .

[0020] According to one embodiment, the apparatus includes components for making user pairing decisions using inter-beam interference estimation in multi-user MIMO (MU-MIMO) scheduling.

[0021] According to one embodiment, the apparatus includes components for calculating multi-user signal + interference plus noise ratio (MU-SINR) using inter-beam interference estimation in MU-MIMO scheduling.

[0022] According to one embodiment, the apparatus includes components for scheduling user equipment jointly served by multiple transmit / receive points (TRP) using inter-beam interference estimation.

[0023] According to a method of a second aspect, including: transmitting beamformed signals on multiple beams using physical channel resources with common frequency and time constraints by a multi-input multi-output (MIMO) antenna; calculating the beamforming gain of each beam in each sub-sector in the coverage area of the multiple beams; determining the beam dominant area of each beam within the coverage area of the multiple beams; within the dominant area of each beam, determining the average value of the beamforming gains of each other beam that is at least partially co-located within the beam dominant area; determining the inter-beam interference estimation as the average interference from each other beam to each beam; and scheduling the transmission of the beams by the MIMO antenna on the physical channel resources with common frequency and time constraints based on the inter-beam interference estimation.

[0024] According to other aspects, a computer-readable storage medium includes code for use by an apparatus which, when executed by a processor, causes the apparatus to perform the above method. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a more complete understanding of the example embodiments, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 A schematic block diagram of an apparatus for including a beam distribution arrangement according to an embodiment is shown;

[0027] Figure 2 The layout of an apparatus according to an example embodiment is schematically shown;

[0028] Figure 3 A part of an exemplary radio access network is shown;

[0029] Figure 4 An example of beam gains (in dB) of several beams in the beam space in the azimuth direction is shown;

[0030] Figure 5 A flowchart for estimating interference between beams according to one embodiment is shown; and

[0031] Figure 6a and Figure 6b Examples of beam pairs according to various embodiments and their average interference (linear) in the beam dominant region are shown. DETAILED DESCRIPTION

[0032] Suitable apparatuses and possible mechanisms for performing interference management are described in more detail below. Although the following focuses on 5G networks, the embodiments further described below are in no way limited to being implemented only in the described networks, but they are applicable to any network implementing MU-MIMO transmission.

[0033] In this regard, reference is first made to Figure 1 and Figure 2 , in which Figure 1 A schematic block diagram of an exemplary apparatus or electronic device 50 that may include an arrangement according to an embodiment is shown. Figure 2 The layout of an apparatus according to an example embodiment is shown. The elements of Figure 1 and Figure 2 will be explained below.

[0034] The electronic device 50 may be, for example, a mobile terminal or user equipment of a wireless communication system. The apparatus 50 may include a housing 30 for containing and protecting the device. The apparatus 50 may also include a display 32 and a keypad 34. Instead of a keypad, the user interface may be implemented as a virtual keyboard or a data input system that is part of a touch-sensitive display.

[0035] The device may include microphone 36 or any suitable audio input that can be a digital or analog signal input. Device 50 may also include an audio output device, such as headphones 38, speakers, or any one of analog audio or digital audio output connections. Device 50 may also include a battery 40 (or the device may be powered by any suitable mobile energy device such as a solar cell, fuel cell, or spring generator). The device may also include a camera 42 capable of recording or capturing images and / or videos. Device 50 may also include an infrared port 41 for short-range line-of-sight communication with other devices. In other embodiments, device 50 may also include any suitable short-range communication solution, such as, for example, a Bluetooth wireless connection or a USB / FireWire wired connection.

[0036] Device 50 may include a controller 56 or a processor for controlling device 50. Controller 56 may be connected to a memory 58, which may store user data and instructions for implementation on controller 56. The memory may be a random access memory (RAM) and / or a read-only memory (ROM). The memory may store computer-readable and computer-executable software including instructions that, when executed, cause the controller / processor to perform the various functions described herein. In some cases, the software may not be directly executable by the processor but may cause a computer (e.g., when compiled and executed) to perform the functions described herein. Controller 56 may also be connected to a codec circuit 54, which is suitable for performing encoding and decoding of audio and / or video data or assisting in the encoding and decoding performed by the controller.

[0037] Device 50 may include a radio interface circuit 52, which is connected to the controller and is suitable for generating wireless communication signals, such as for communicating with a cellular communication network, a wireless communication system, or a wireless local area network. Device 50 may also include an antenna 44 connected to radio interface circuit 52 for transmitting radio frequency signals generated at radio interface circuit 52 to (a) other device(s) and receiving radio frequency signals from (a) other device(s).

[0038] In the following, an access architecture based on Advanced Long Term Evolution (LTE-A) or New Radio (NR, 5G) will be used as an example of an access architecture to which different exemplary embodiments can be applied. However, the embodiments are not limited to such an architecture. Those skilled in the art can understand that by appropriately adjusting parameters and processes, the embodiments can also be applied to other types of communication networks with suitable components. Some examples of other options for applicable systems are Universal Mobile Telecommunications System (UMTS) Radio Access Network (UTRAN or E-UTRAN), Long Term Evolution (LTE, the same as E-UTRA), Wireless Local Area Network (WLAN or WiFi), Worldwide Interoperability for Microwave Access (WiMAX), Bluetooth Personal Communication Service (PCS), Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, sensor networks, Mobile Ad-hoc Networks (MANET), and Internet Protocol Multimedia Subsystem (IMS) or any combination thereof.

[0039] Figure 3 An example of a simplified system architecture is depicted that shows only some elements and functional entities, all of which are logical units and whose implementation may be different from what is shown. Figure 3 The connections shown in are logical connections; the actual physical connections may be different. It is obvious to those skilled in the art that the system generally also includes other functions and structures in addition to Figure 3 the functions and structures shown in. However, the embodiments are not limited to the system given as an example, and those skilled in the art can apply the solution to other communication systems with the necessary attributes.

[0040] Figure 3 The example of shows a part of an example radio access network.

[0041] Figure 3 User equipments 300 and 302 are shown, which are configured to make a wireless connection with an access node (such as (e / g)NodeB) 304 providing the cell on one or more communication channels in the cell. The physical link from the user equipment to the (e / g)NodeB is called the uplink or reverse link, and the physical link from the (e / g)NodeB to the user equipment is called the downlink or forward link. It should be understood that the (e / g)NodeB or its functionality can be implemented by any entity such as a node, host, server, or access point suitable for this purpose.

[0042] A communication system typically includes more than one (e / g)NodeB. In this case, the (e / g)NodeBs can also be configured to communicate with each other via wired or wireless links designed for this purpose. These links can be used for signaling purposes. An (e / g)NodeB is a computing device configured to control the radio resources of the communication system coupled thereto. A NodeB can also be referred to as a base station, an access point, or any other type of interface device, including a relay station capable of operating in a wireless environment. An (e / g)NodeB includes or is coupled to a transceiver. A connection from the transceiver of the (e / g)NodeB is provided to an antenna unit, which establishes a two-way radio link to a user equipment. The antenna unit can include multiple antennas or antenna elements. The (e / g)NodeB is further connected to a core network 310 (CN or Next Generation Core NGC). Depending on the system, the counterpart on the CN side can be a Serving Gateway (S-GW, routing and forwarding user data packets), a Packet Data Network Gateway (P-GW) for providing connectivity of the user equipment (UE) to an external packet data network, or a Mobility Management Entity (MME), etc. The CN can include network entities or nodes that can be referred to as management entities. Examples of network entities include at least an Access and Mobility Management Function (AMF).

[0043] A user equipment (also referred to as a user equipment (UE), a user terminal, a terminal device, a wireless device, a mobile station (MS), etc.) illustrates a type of device to which resources on an air interface are allocated and assigned, and thus any feature described herein for a user equipment can be implemented with a corresponding network device such as a relay node, an eNB, and a gNB. An example of such a relay node is a Layer 3 relay towards a base station (self-backhaul relay).

[0044] A user equipment generally refers to a portable computing device, which includes a wireless mobile communication device operating with or without a subscriber identity module (SIM), including but not limited to the following types of devices: a mobile station (mobile phone), a smart phone, a personal digital assistant (PDA), a cellular phone, a device using a wireless modem (such as an alarm or measurement device, etc.), a laptop computer and / or a touch screen computer, a tablet computer, a game console, a laptop computer, and a multimedia device. It should be understood that the user equipment can also be an almost exclusive uplink-only device, an example of which is a camera or a video camera that uploads images or video clips to the network. The user equipment can also be a device capable of operating in an Internet of Things (IoT) network, which is a scenario where the network provides the ability to transfer data for objects without the need for person-to-person or human-machine interaction. Therefore, the user equipment can be an IoT device. The user equipment can also utilize the cloud. In some applications, the user equipment can include a small portable device with a radio part (such as a watch, headphones, or glasses), and the computing is performed in the cloud. The user equipment (or a layer 3 relay node in some embodiments) is configured to perform one or more user equipment functions. The user equipment can also be referred to as a subscriber unit, a mobile station, a remote terminal, an access terminal, a user terminal, or a user equipment (UE), to name just a few names or devices.

[0045] The various technologies described herein can also be applied to cyber-physical systems (CPS) (systems of collaborative computing elements that control physical entities). CPS can enable and utilize a large number of interconnected ICT devices (sensors, actuators, processor microcontrollers, etc.) embedded in physical objects at different locations. A mobile cyber-physical system (where the physical system under discussion has inherent mobility) is a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robots and electronic products carried by humans or animals.

[0046] In addition, although the device has been depicted as a single entity, different units, processors, and / or memory units ( Figure 1 not all shown therein) can be implemented.

[0047] 5G supports the use of multiple-input multiple-output (MIMO) antennas, far more base stations or nodes than LTE (the so-called small cell concept), including macro sites that cooperate with smaller base stations and employ various radio technologies, depending on service requirements, use cases, and / or available spectrum. The access nodes of the radio network form transmit / receive (TX / Rx) points (TRPs), and the UE expects to access a network of multiple TRPs with at least partial overlap, such as macro cells, small cells, picocells, femtocells, remote radio heads, relay nodes, etc. The access nodes can be provided with massive MIMO antennas capable of using multiple simultaneous radio beams for communication with the UE, i.e., very large antenna arrays consisting of, for example, hundreds of antenna elements, implemented in a single antenna panel or multiple antenna panels. The UE can be provided with a MIMO antenna having an antenna array consisting of, for example, dozens of antenna elements, implemented in a single antenna panel or multiple antenna panels. Thus, the UE can access one TRP using one beam, one TRP using multiple beams, multiple TRPs using one (common) beam, or multiple TRPs using multiple beams.

[0048] 4G / LTE networks support some multi-TRP schemes, but in 5G NR, the multi-TRP feature is enhanced, e.g., by transmitting multiple control signals via multiple TRPs, which enables an increase in link diversity gain. Additionally, high carrier frequencies (e.g., millimeter waves) together with massive MIMO antennas require new beam management procedures for multi-TRP technologies.

[0049] 5G mobile communications supports a wide range of use cases and related applications, including video streaming, augmented reality, different data sharing methods, and various forms of machine-type applications (such as (massive) machine-type communication (mMTC), including vehicle safety, different sensors, and real-time control. 5G is expected to have multiple radio interfaces, i.e., below 6 GHz, cmWave, and mmWave, and is also capable of integrating with existing traditional radio access technologies (such as LTE). At least in the early stages, integration with LTE can be achieved as a system where macro coverage is provided by LTE while the 5G radio interface accesses from small cells aggregated to LTE. In other words, 5G plans to support both inter-RAT interoperability (such as LTE-5G) and inter-RI interoperability (inter-radio interface interoperability, such as below 6 GHz - cmWave, below 6 GHz - cmWave - mmWave). One of the concepts considered for use in 5G networks is network slicing, where multiple independent and dedicated virtual subnets (network instances) can be created in the same infrastructure to run services with different requirements for latency, reliability, throughput, and mobility.

[0050] The frequency bands for 5G NR are divided into two frequency ranges: Frequency Range 1 (FR1), which includes frequency bands below 6 GHz, i.e., the bands traditionally used by previous standards, and new bands extending to cover potential new spectrum products from 410 MHz to 7125 MHz, and Frequency Range 2 (FR2), which includes frequency bands from 24.25 GHz to 52.6 GHz. Thus, FR2 includes frequency bands in the mmWave range, which, due to their shorter range and higher available bandwidth, require some different approaches in radio resource management compared to the bands in FR1.

[0051] The current architecture in LTE networks is fully distributed in the radio and fully centralized in the core network. Low-latency applications and services in 5G require bringing content closer to the radio, resulting in local breakout and multi-access edge computing (MEC). 5G enables analysis and knowledge generation to occur at the data source. This approach requires leveraging resources that may not be continuously connected to the network, such as laptops, smartphones, tablets, and sensors. MEC provides a distributed computing environment for application and service hosting. It also has the ability to store and process content closer to cellular users to accelerate response times. Edge computing encompasses a wide range of technologies, such as wireless sensor networks, mobile data collection, mobile signature analysis, collaborative distributed peer-to-peer ad hoc networking, and processing that can also be classified as local cloud / fog computing and grid / mesh computing, dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, self-healing autonomous networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or latency-critical), critical communications (autonomous vehicles, traffic safety, real-time analysis, time-critical control, healthcare applications).

[0052] The communication system is also capable of communicating with other networks such as the public switched telephone network or the Internet 312, or leveraging the services provided by them. The communication network is also capable of supporting the use of cloud services, e.g., at least a part of the core network operations can be performed as cloud services (which is depicted by the "cloud" 314 in Figure 3 ). The communication system may also include a central control entity, etc., to provide facilities for networks of different operators to cooperate, e.g., in spectrum sharing.

[0053] Edge clouds can be brought into the radio access network (RAN) by leveraging network function virtualization (NFV) and software-defined networking (SDN). Using edge clouds may mean performing access node operations at least partially in servers, hosts, or nodes operationally coupled to remote radio heads or base stations including radio parts. Node operations may also be distributed among multiple servers, nodes, or hosts. The application of the cloud RAN architecture enables RAN real-time functions to be executed on the RAN side (in the distributed unit DU), and non-real-time functions to be executed in a centralized manner (in the centralized unit CU 308).

[0054] It should also be understood that the distribution of work between core network operations and base station operations may be different from that of LTE, or may not even exist. Some other technological advancements that may be used are big data and all-IP, which may change the way the network is built and managed. 5G (or New Radio, NR) networks are designed to support multiple hierarchies, where MEC servers can be placed between the core and base stations or Node Bs (gNBs). It should be understood that MEC can also be applied to 4G networks. A gNB is the next-generation Node B (or new Node B) that supports 5G networks (i.e., NR).

[0055] 5G can also utilize non-terrestrial nodes 306 (such as access nodes) to enhance or supplement the coverage of 5G services - for example, by providing backhaul, wireless access to wireless devices, service continuity for machine-to-machine (M2M) communications, service continuity for Internet of Things (IoT) devices, service continuity for passengers on vehicles, ensuring service availability for critical communications, and / or ensuring service availability for future railway / sea / air communications. Non-terrestrial nodes can have a fixed position relative to the Earth's surface, or non-terrestrial nodes can be mobile non-terrestrial nodes that can move relative to the Earth's surface. Non-terrestrial nodes can include satellites and / or HAPS. Satellite communications can utilize geostationary orbit (GEO) satellite systems, but can also utilize low Earth orbit (LEO) satellite systems, especially mega-constellations (systems in which hundreds (nanos) of satellites are deployed). Each satellite in a mega-constellation can cover several satellite-enabled network entities that create ground cells. Ground cells can be created by ground relay nodes 304 or by gNBs located on the ground or in satellites.

[0056] Those skilled in the art will understand that the depicted system is only an example of a part of a radio access system, and in practice, the system may include multiple (e / g)NodeBs, user equipment may access multiple radio cells, and the system may also include other devices, such as physical layer relay nodes or other network elements, etc. At least one of the (e / g)NodeBs may be a home (e / g)NodeB. Additionally, in the geographical area of a radio communication system, multiple different types of radio cells and multiple radio cells may be provided. The radio cells may be macro cells (or umbrella cells), which are large cells, typically having a diameter of up to several tens of kilometers, or they may be smaller cells, such as micro cells, femto cells, or pico cells. Figure 1 The (e / g)NodeBs can provide any type of these cells. A cellular radio system can be implemented as a multi-layer network including multiple types of cells. Generally, in a multi-layer network, one access node provides one or more cells of one type, so multiple (e / g)NodeBs are required to provide such a network structure.

[0057] To meet the need for improving the deployment and performance of communication systems, the concept of "plug-and-play" (e / g)NodeBs has been introduced. Generally, in addition to the home (e / g)NodeB (H(e / g)NodeB), a network capable of using "plug-and-play" (e / g)NodeBs also includes a home NodeB gateway, or HNB-GW ( Figure 1 not shown in the figure). The HNB gateway (HNB-GW), which is typically installed within the operator's network, can aggregate traffic from a large number of HNBs back to the core network.

[0058] The Radio Resource Control (RRC) protocol is used in various wireless communication systems to define the air interface between a UE and a base station (such as an eNB / gNB). This protocol is specified by 3GPP in TS 36.331 for LTE and in TS 38.331 for 5G. In terms of RRC, a UE can operate in the idle mode or in the connected mode in both LTE and 5G, where the radio resources available to the UE depend on the mode the UE is currently in. In 5G, a UE can also operate in the inactive mode. In the RRC idle mode, the UE has no connection for communication, but the UE is able to listen for paging messages. In the RRC connected mode, the UE can operate in different states, such as CELL_DCH (Dedicated Channel), CELL_FACH (Forward Access Channel), CELL_PCH (Cell Paging Channel), and URA_PCH (URA Paging Channel). The UE can communicate with the eNB / gNB via various logical channels, such as Broadcast Control Channel (BCCH), Paging Control Channel (PCCH), Common Control Channel (CCCH), Dedicated Control Channel (DCCH), and Dedicated Traffic Channel (DTCH).

[0059] Transitions between states are controlled by the state machine of the RRC. When the UE powers on, it is in the disconnected mode / idle mode. The UE can transition to the RRC connected mode either through an initial attachment or through connection establishment. If there is no activity from the UE for a short period of time, the eNB / gNB can pause its session by switching to RRC Inactive and can resume its session by switching back to the RRC connected mode. The UE can switch from the RRC connected mode or the RRC inactive mode to the RRC idle mode.

[0060] Actual user and control data from the network to the UE are transmitted via downlink physical channels, which in 5G include the Physical Downlink Control Channel (PDCCH) that carries the necessary downlink control information (DCI), the Physical Downlink Shared Channel (PDSCH) that carries the user's user data and system information, and the Physical Broadcast Channel (PBCH) that carries the necessary system information to enable the UE to access the 5G network.

[0061] User and control data from the UE to the network are transmitted via uplink physical channels, which in 5G include the Physical Uplink Control Channel (PUCCH) that is used for uplink control information (including HARQ feedback acknowledgments, scheduling requests, and downlink channel state information for link adaptation), the Physical Uplink Shared Channel (PUSCH) that is used for uplink data transmission, and the Physical Random Access Channel (PRACH) that is used by the UE to request connection establishment (referred to as random access).

[0062] For 5G technology, one of the most important design goals is to improve the metrics of reliability and latency, as well as network resilience and flexibility.

[0063] Especially when considering the operation of the UE in frequency range 2 (FR2; 24.25 GHz to 52.6 GHz) (including the mmWave range), the UE implementation is expected to have multiple antenna panels (multi-panel UE, MPUE) to perform beam steering over a large solid angle, thus aiming to maximize reliability.

[0064] In FR2, both the gNB and the UE are expected to operate using "narrow" beams, which means that the gNB operates with a radiation pattern that is narrower than a sector-wide beam, and the UE operates with a radiation pattern that is narrower than an omnidirectional beam. By applying amplitude and phase precoding / beamforming weights (i.e., beam weights), signals are transmitted from all elements in the antenna array in the desired direction, thus enabling beamformed data transmission. Beamformed transmissions from a large antenna array in massive MIMO from a network element such as a base station (gNb) provide enhanced signal strength to the desired user equipment (UE), but can cause significant interference to other UEs if the beam creates unwanted interference in the direction of other UEs.

[0065] Multiple users can be scheduled simultaneously on frequency-time resources in multi-user MIMO (MU-MIMO), while transmitting beamformed signals in the dominant direction of the users. MU-MIMO improves system throughput by co-scheduling multiple UEs in the same time slot on the same physical resource block (PRB). The advantages of MU-MIMO can be achieved only when the beamformed transmission towards one UE does not cause too much interference to other co-scheduled UEs.

[0066] The reason for beam-based operation depends on the need to increase the array / antenna gain to compensate for the higher coupling losses at mmWaves, but it also brings some technical limitations. Beam-based operation requires a good beam correspondence between the gNB and the UE, which is difficult to maintain because the beams are very narrow and thus have a large degree of freedom in the spatial domain, and it is very sensitive to blockage and beam misalignment between the gNB and the UE, as well as the mobility and rotation effects of the UE.

[0067] One way to calculate the correlation between beams is to perform a dot product or inner product on their beam weights, i.e., where b1 and b2 are the n TRx ×1 length beam weight vectors of beam 1 and beam 2. Sometimes, interference is also calculated as where b′1 and b′2 are corresponding to single polarization Long beam weight vector. This method may lead to an inaccurate estimation of the interference of one beam to another beam. This is because the metric only calculates the interference of one beam in the boresight beam direction of another beam, but when the UE reports this beam as the best beam, the UE can be located at any position in the beam dominant direction of this beam.

[0068] Figure 4 An example of the beam gain (in dB) in the beam space of several beams in the azimuth direction is shown. The beam dominant region of a beam may consist of the main lobe and some regions in its side lobes. The interference to a beam may be due to the main lobe or side lobe of another beam appearing in its beam dominant region. For example, the dominant region of beam id 1 is shown below, that is, the region where beam id 1 has the maximum beamforming gain compared to all other beams. As observed, even though beam 16 seems to be zero in the beam pointing direction of beam 1, and beam 8 has a greater interference in the boresight of beam 1, the side lobe of beam 16 generates more interference in the dominant region of beam 1 compared to beam 8.

[0069] It should be noted that if only the inner product of the beam weight vectors is used as an indicator of interference, this difference will not be revealed. Beam 16 and beam 1 will have an inner product of 0 because the two beam weight vectors are orthogonal, while beam 8 and beam 1 will have a greater inner product. However, the interference of beam 16 to beam 1 is greater than that of beam 8. Therefore, calculating the interference of the inner product of the beam weight vectors is not sufficient to determine the correlation or interference between them, but rather the entire azimuth and elevation space needs to be considered.

[0070] Hereinafter, enhanced methods for estimating inter-beam interference will be described in more detail according to various embodiments.

[0071] The method is disclosed in Figure 5 the flowchart as reflecting the operation of a network element (such as an access node, e.g., a base station (gNb)), where the method includes transmitting (500) a beamformed signal on multiple beams by a plurality of multiple-input multiple-output (MIMO) antennas using physical channel resources with common frequency and time limitations; calculating (502) the beamforming gain of each beam in each sub-sector in the coverage area of the multiple beams; determining (504) the beam dominant region of each beam within the coverage area of the multiple beams; within the dominant region of each beam, determining (506) the average value of the beamforming gains of each other beam that is at least partially co-located within the beam dominant region; determining (508) the inter-beam interference estimate as the average interference of each beam from each of the other beams; based on the inter-beam interference estimate, scheduling (510) the transmission of the beams by the MIMO antennas on the physical channel resources with common frequency and time limitations.

[0072] Thus, the inter-beam interference is calculated as the average interference power generated by each beam (the first beam) on another beam (the second beam), as the average beamforming gain of the first beam in the beam dominant region of the second beam. The basic principle behind this method is that when a specific UE selects the second beam as its best beam, this can occur in any sub-sector where the second beam has the maximum beamforming gain. However, the network side, such as the gNB, does not know the (multiple) sub-sectors where the dominant path of the UE is located. Therefore, it can be assumed that the dominant path of the UE is equally likely to be located in any sub-sector where the second beam is the dominant beam. Given this, the interference of the first beam on the second beam is calculated as the average beamforming gain of the first beam in the beam dominant region of the second beam.

[0073] According to one embodiment, a sub-sector is defined as a range of azimuth and elevation angles.

[0074] Therefore, a sub-sector is the angular span of the region of interest of azimuth and elevation angles in the coverage area of a sector or multiple sectors, where the angular span can be quantified with some predefined azimuth and elevation granularity, such as 1°. The angular span used to calculate beam interference can be: for example, for a 120° cell opening, the angular span with azimuth from -60° to +60° and elevation from -20° to +10°, where a granularity of 1° is used for both.

[0075] In each sub-sector, the beam with the highest gain can be found for each (azimuth, elevation) angle pair. The set of angles can be referred to as the beam dominant region of beam 1, where (az, el) are the azimuth and elevation angles respectively belonging to the sub-sector, that is, the quantized set of angles in the sector coverage area, and B j (az, el) is the beamforming gain of beam j in the direction (az, el).

[0076] According to one embodiment, the method includes storing the average interference value of each beam from each of the other beam values in a two-dimensional table.

[0077] Therefore, for each beam, in its beam dominant region, the average interference averaged over the angles in the beam dominant region is calculated from each of the other beams among the other beams. These values can be stored in a two-dimensional table, and a simplified example is shown below. In the table, I x_y represents the average interference of beam y on beam x in the beam dominant region of beam x.

[0078]

[0079]

[0080] In the following, some steps related to the method and some embodiments are described in more detail for calculating the mapping of beam-to-beam average interference.

[0081] Therefore, the beam gain of each beam is calculated for each azimuth and elevation angle pair in one or more sector coverage areas. According to one embodiment, the beam weight vector of beam i is given by the azimuth and elevation on the n TRX / 2×1 length weight vector b i The beamforming gain for beam i is calculated as:

[0082] B i (θ, φ) = ||H θ,φ b i || 2

[0083] where H θ，φ is the 1×n TRX / 2 steering vector in the direction of (θ, φ), and n TRX is the number of transmit-receive units (TRXs) of the transmitter. For example, the steering vector can be calculated as specified in 3GPP 38.901 for the generation of the 3D spatial channel model.

[0084] According to one embodiment, the beam dominant region of each beam i is determined as follows:

[0085]

[0086] where R is the set of all (θ, φ) angle pairs in the coverage area of interest according to a predefined quantization strategy, and B x (θ, φ) is the beamforming gain of beam x at azimuth and elevation angles θ and respectively.

[0087] As mentioned above, within the dominant region of each beam, the average value of the beam gains of all other beams is determined. According to one embodiment, the average interference from beam b j to b i is calculated as:

[0088]

[0089] where |BDR i | is the cardinality of the set BDR i or the number of entries in the set BDR i .

[0090] The interference I calculated as above x_yIt can be used to calculate multi - user signal - to - interference - plus - noise ratio (MU - SINR), proportional fair scheduling (PF) metrics, etc., for user selection. MU - SINR can in turn be used in a link adaptation algorithm for modulation and coding scheme (MCS) selection for co - scheduled UEs.

[0091] According to one embodiment, inter - beam interference estimation is used for user pairing decisions in MU - MIMO scheduling. Thus, as shown above, an inter - beam interference table can be used to co - schedule those users whose serving beams interfere less with each other in a MU - MIMO manner to improve spectral efficiency.

[0092] According to one embodiment, inter - beam interference estimation is used for MU - SINR calculation in MU - MIMO scheduling. Thus, MU - SINR is calculated based on SU - SINR while taking into account the MU interference between co - scheduled UEs. MU - SINR is used to determine the MCS. An appropriate MCS improves throughput by using the best MCS for the expected channel conditions of the transmission. The MU - SINR for user u at layer l u is calculated as follows:

[0093]

[0094] where P is the total number of co - scheduled UEs, and u′ represents the index of the co - scheduled interfering UEs. SU - SINR is calculated by the UE assuming that all base - station transmission power is allocated to the UE of interest, but during MU - MIMO transmission, the transmission power is evenly divided among the P co - scheduled UEs. The beam pair used for transmission at layer l of user u′ u′ interferes with the beam at layer l of user u u as

[0095] According to one embodiment, inter - beam interference estimation can also be used to schedule users jointly served by multiple transmit / receive points (TRPs). UEs within the coverage of multiple TRPs (cells) are served by beams from these TRPs that interfere the most with each other. Thus, the performance of the UE is improved when multiple TRPs use their most overlapping beams for serving.

[0096] Figure 6a and Figure 6bSome exemplary curves showing beam pairs and average interference (linear) in the beam dominant region are presented. The measurement arrangement behind the results includes an antenna array with dimensions 12x8x2, where 3 adjacent radiators in the vertical direction are combined into a transmit-receive unit (TRX). There are a total of 225 oversampled DFT beams, and thus a table of size 225x225 is created to provide the average interference from each beam to each other beam.

[0097] In Figure 6a the example shown, beam IDs 1 and 2 are closer to each other in azimuth and completely overlap in elevation. Thus, these beams have a large overlap with each other in their dominant regions. The average interference I 1_2 of beam ID 2 on beam ID 1 is 31.46 dB, and the average interference I 2_1 of beam ID 1 on beam ID 2 is 31.5 dB.

[0098] In Figure 6b the example shown, the correlation between beam 14 and 6 shows that these two beams are spaced far enough apart in azimuth, and thus the correlation between their main lobes is not significant. Only the side lobes of these beams cause interference in the beam dominant regions of each other beam among other beams. Thus the interference is low, i.e., I 14_6 is 4.96 dB and I 6_14 is 9.87 dB.

[0099] As shown in the above two examples, the interference of different beams can vary greatly. Thus, accurate calculation of the inter-beam interference as defined by the method and related embodiments enables a significant increase in the MU-MIMO gain.

[0100] According to one aspect, a device such as a base station (gNb) includes: a multiple-input multiple-output (MIMO) antenna for transmitting beamformed signals on multiple beams using physical channel resources with common frequency and time limitations; components for calculating the beamforming gain of each beam in each sub-sector in the coverage area of the multiple beams; components for determining the beam dominant region of each beam within the coverage area of the multiple beams; components for determining, within the dominant region of each beam, the average value of the beamforming gains of each other beam that is at least partially co-located within the beam dominant region; components for determining the inter-beam interference estimate as the average interference from each other beam to each beam; and components for scheduling the transmission of beams on the physical channel resources with common frequency and time limitations by the MIMO antenna based on the inter-beam interference estimate.

[0101] According to one embodiment, the apparatus includes components for storing, in a two-dimensional table, the value of the average interference of each beam from each of the other beam values.

[0102] According to one embodiment, a sub-sector is defined as a range of azimuth and elevation angles.

[0103] According to one embodiment, the apparatus includes components for calculating the beamforming gain of beam i, where the beam weight vector of beam i is an n TRX / 2×1 length weight vector b i given, and the beamforming gain is calculated as:

[0104] B i (θ, φ) = ||H θ,φ b i || 2

[0105] where H θ，φ is a 1×n TRX / 2 steering vector in the (θ, φ) direction.

[0106] According to one embodiment, the apparatus includes components for determining the beam dominant region of each beam i as follows:

[0107]

[0108] where R is a set of all (θ, φ) angle pairs in the coverage area of interest according to a predefined quantization strategy.

[0109] According to one embodiment, the apparatus includes components for calculating the average interference from beam b j to b i as follows:

[0110]

[0111] where |BDR i | is the cardinality of the set BDR i , or the number of entries in the set BDR i .

[0112] According to one embodiment, the apparatus includes components for using inter-beam interference estimation in multi-user MIMO (MU-MIMO) scheduling to make user pairing decisions.

[0113] According to one embodiment, the apparatus includes components for using inter-beam interference estimation in MU-MIMO scheduling to calculate the multi-user signal + interference plus noise ratio (MU-SINR).

[0114] According to one embodiment, the apparatus includes components for scheduling user equipment jointly served by multiple transmit / receive points (TRPs) using inter-beam interference estimation.

[0115] The components mentioned herein and in related embodiments may include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the execution of the apparatus.

[0116] The apparatus according to another aspect includes at least one processor and at least one memory, the at least one memory storing computer program code thereon, the at least one memory and the computer program code being configured to, together with the at least one processor, cause the apparatus to at least perform: transmitting beamformed signals on multiple beams using physical channel resources with common frequency and time constraints by a multiple-input multiple-output (MIMO) antenna; calculating the beamforming gain of each beam in each sub-sector in the coverage area of the multiple beams; determining the beam dominant region of each beam within the coverage area of the multiple beams; determining, within the dominant region of each beam, the average value of the beamforming gains of each other beam that is at least partially co-located within the beam dominant region; determining the inter-beam interference estimation as the average interference of each beam from each of the other beams; and scheduling the transmission of beams by the MIMO antenna on the physical channel resources with common frequency and time constraints based on the inter-beam interference estimation.

[0117] Another aspect relates to a computer program product stored on a non-transitory storage medium, the computer program product including computer program code that, when executed by at least one processor, causes the apparatus to at least perform: transmitting beamformed signals on multiple beams using physical channel resources with common frequency and time constraints by a multiple-input multiple-output (MIMO) antenna; calculating the beamforming gain of each beam in each sub-sector in the coverage area of the multiple beams; determining the beam dominant region of each beam within the coverage area of the multiple beams; determining, within the dominant region of each beam, the average value of the beamforming gains of each other beam that is at least partially co-located within the beam dominant region; determining the inter-beam interference estimation as the average interference of each beam from each of the other beams; and scheduling the transmission of beams by the MIMO antenna on the physical channel resources with common frequency and time constraints based on the inter-beam interference estimation.

[0118] In general, the various embodiments of the present invention may be implemented in hardware or a dedicated circuit or any combination thereof. Although aspects of the present invention may be illustrated and described as block diagrams or using some other graphical representation, it is well known that, by way of non-limiting example, the blocks, devices, systems, techniques or methods described herein may be implemented in hardware, software, firmware, a dedicated circuit or logic, general purpose hardware or a controller or other computing device or some combination thereof.

[0119] Embodiments of the present invention may be practiced in various components such as integrated circuit modules. The design of an integrated circuit is essentially a highly automated process. Sophisticated and powerful software tools can be used to transform a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0120] Programs, such as those provided by Synopsys, Inc. of Mountain View, California and Cadence Design, Inc. of San Jose, California, use well-established design rules as well as pre-stored libraries of design modules to automatically route conductors and to position components on a semiconductor chip. Once the design of the semiconductor circuit is complete, the design results in a standardized electronic format (e.g., Opus, GDSII, etc.) can be transferred to a semiconductor manufacturing facility or "fab" for fabrication.

[0121] The foregoing description has provided a complete and informative description of the exemplary embodiments of the present invention by way of examples and non-limiting examples. However, various modifications and adaptations will become apparent to those skilled in the relevant art when the above description is read in conjunction with the accompanying drawings and the appended examples. However, all such and similar modifications to the teachings of the present invention will still fall within the scope of the present invention.

Claims

1. An apparatus for determining beam interference, comprising: Multiple-input, multiple-output (MIMO) antennas for transmitting beamformed signals on multiple beams using common frequency and time-constrained physical channel resources; means for calculating a beamforming gain for each beam in each sub-sector within a coverage area of the plurality of beams; means for determining a beam dominant area for each beam within said coverage area of said plurality of beams; means for determining, within the dominant region of each beam, an average of the beamforming gains of each other beam at least partially co-located within the beam dominant region; means for determining an inter-beam interference estimate as an average interference from each of said other beams; as well as means for scheduling transmissions of the plurality of beams by the MIMO antennas on the common frequency and time restricted physical channel resources based on the inter-beam interference estimate.

2. The apparatus according to claim 1, comprising: Means for storing in a two dimensional table the value of said average interference for each beam from every other beam.

3. The apparatus according to claim 1 or 2, wherein the sub-sector is defined as a range of azimuth and elevation angles.

4. The apparatus according to claim 3, comprising: A component for calculating the beamforming gain for beam i, where the beam weight vector of beam i is an n TRX / 2×1 length weight vector b i given, and the beamforming gain is calculated as: B i (θ,φ)=||H θ，φ b i || 2 Where H θ，φ is a 1×n TRX / 2 steering vector in the (θ, φ) direction, and n TRX is the number of transmit-receive units (TRXs) of the transmitter.

5. The apparatus according to claim 3, comprising: The means for determining the beam dominant region for each beam i as: where R is a set of all (θ, φ) angle pairs in the coverage area of interest according to a predefined quantization strategy, and B x (θ, φ) is the beamforming gain of beam x at azimuth and elevation angles θ and respectively at that location.

6. The apparatus according to claim 5, comprising: Component for calculating the average interference from beam b j to b i : where |BDR i | is the cardinality of the set BDR i , or the number of entries in the set BDR i , B j (θ, φ) is the beamforming gain of beam j at azimuth angle θ and elevation angle respectively, where θ is the azimuth angle and is the elevation angle.

7. The apparatus according to claim 1, comprising: Means for using inter-beam interference estimation for user pairing decisions in multi-user MIMO (MU-MIMO) scheduling.

8. The apparatus according to claim 1, comprising: Means for multi-user signal-plus-interference-and-noise ratio (MU-SINR) calculation using inter-beam interference estimation in MU-MIMO scheduling.

9. The apparatus according to claim 1, comprising: Means for using the inter-beam interference estimate to schedule user equipment jointly served by multiple transmit / receive points (TRPs).

10. A method for determining beam interference, comprising: Transmitting beamformed signals on multiple beams by multiple-input multiple-output (MIMO) antennas using common frequency and time-constrained physical channel resources; calculating a beamforming gain for each beam in each sub-sector within a coverage area of the plurality of beams; determining a beam dominant area for each beam within the coverage area of the plurality of beams; determining, within the dominant region of each beam, an average of the beamforming gains of each other beam at least partially co-located within the beam dominant region; determining an inter-beam interference estimate as an average interference from each of each of said other beams; as well as The MIMO antennas are scheduled to transmit the multiple beams on the common frequency and time-constrained physical channel resources based on the inter-beam interference estimate.

11. The method according to claim 10, comprising: The value of the average interference for each beam from every other beam is stored in a two-dimensional table.

12. The method according to claim 10 or 11, wherein the sub-sector is defined as a range of azimuth and elevation angles.

13. The method according to claim 12, comprising: Calculate the beamforming gain for beam i, where the beam weight vector of beam i is an n TRX / 2×1 length weight vector b i given, and the beamforming gain is calculated as: B i (θ, φ) = ||H θ，φ b i || 2 Among them H θ，φ is 1×n in the (θ, φ) direction TRX / 2 steering vector.

14. The method according to claim 12, comprising: The beam-dominant region of each beam i is determined as: where R is a set of all (θ, φ) angle pairs in the coverage area of interest according to a predefined quantization strategy, B i (θ, φ) is the beamforming gain of beam i at azimuth and elevation angles θ and respectively, B j (θ, φ) is the beamforming gain of beam j at azimuth and elevation angles θ and respectively, where θ is the azimuth angle and is the elevation angle.

15. The method according to claim 14, comprising: Calculate the average interference from beam b j to b i as follows: where |BDR i | is the cardinality of the set BDR i , or the number of entries in the set BDR i , B j (θ, φ) is the beamforming gain of beam j at azimuth and elevation angles θ and respectively, where θ is the azimuth angle and is the elevation angle.

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