Hybrid beamforming for uplink transmission

Abstract

A method is disclosed, the method comprising determining a transmission beam for a downlink transmission, providing first beamforming instructions to a transmission path comprising a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray; determining, for the first antenna subarray, at least one receive beam as a first receive beam and, for the second antenna subarray, at least one receive beam as a second receive beam for receiving an uplink transmission; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam; and transmitting the downlink transmission using the transmission beam and receiving the uplink transmission using the first receive beam and the second receive beam.

Description

TECHNICAL FIELD

[0001] The following exemplary embodiments relate to wireless communication, and using hybrid beamforming for uplink transmission. BACKGROUND

[0002] Wireless communication networks, such as cellular communication networks, evolve, and techniques to achieve improved coverage and enhanced capacity are of interest. Furthermore, techniques will also be developed to enable desired capabilities in wireless communication. Beamforming, where multiple columns of antenna elements work together to produce a high-gain signal, can be used to enhance coverage. SUMMARY

[0003] The scope of protection sought and the subject matter defined by the various embodiments of the present invention is set forth by the independent claims. The exemplary embodiments and features that are not the subject of independent claims described in the present specification are to be interpreted as examples useful in understanding the various embodiments of the present invention.

[0004] According to a first aspect, there is provided an apparatus comprising means for: determining a transmission beam for a downlink transmission; providing first beamforming instructions to a transmission path comprising a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using a delay line, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using a delay line, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmission beam, and receiving the uplink transmission using the first receive beam and the second receive beam.

[0005] According to a first aspect, in some example embodiments, the component comprises: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause performance of the apparatus.

[0006] According to a second aspect, there is provided an apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least perform: determining a transmission beam for a downlink transmission; providing first beamforming instructions to a transmission path comprising a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using a delay line, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using a delay line, and wherein the first phase shifter and the second phase shifter are both connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmission beam, and receiving the uplink transmission using the first receive beam and the second receive beam.

[0007] According to a third aspect, there is provided a method comprising: determining a transmit beam for a downlink transmission; providing first beamforming instructions to a transmit path comprising a digital-to-analog converter and an antenna column for forming the transmit beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using delay lines, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using delay lines, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmit beam, and receiving the uplink transmission using the first receive beam and the second receive beam.

[0008] According to the third aspect, in some example embodiments, the method is a computer-implemented method.

[0009] According to a fourth aspect, there is provided a computer program comprising instructions causing an apparatus to perform at least the following: determining a transmit beam for a downlink transmission; providing first beamforming instructions to a transmit path comprising a digital-to-analog converter and an antenna column for forming the transmit beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using delay lines, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using delay lines, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmit beam, and receiving the uplink transmission using the first receive beam and the second receive beam.

[0010] According to a fifth aspect, there is provided a computer program comprising instructions stored thereon for performing at least the following: determining a transmit beam for a downlink transmission; providing first beamforming instructions to a transmit path comprising a digital-to-analog converter and an antenna column for forming the transmit beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using delay lines, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using delay lines, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmit beam, and receiving the uplink transmission using the first receive beam and the second receive beam.

[0011] According to a sixth aspect, there is provided a non-transitory computer- readable medium comprising program instructions for causing an apparatus to perform at least the following: determining a transmission beam for a downlink transmission; providing first beamforming instructions to a transmission path comprising a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using a delay line, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using a delay line, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmission beam, and receiving the uplink transmission using the first receive beam and the second receive beam.

[0012] According to a seventh aspect, there is provided a non-transitory computer- readable medium comprising program instructions stored thereon for performing at least the following: determining a transmit beam for a downlink transmission; providing first beamforming instructions to a transmit path comprising a digital-to-analog converter and an antenna column for forming the transmit beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using a delay line, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using a delay line, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmit beam, and receiving the uplink transmission using the first receive beam and the second receive beam.

[0013] According to an eighth aspect, there is provided a computer readable medium comprising program instructions stored thereon for performing at least the following: determining a transmission beam for a downlink transmission; providing first beamforming instructions to a transmission path comprising a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using delay lines, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using delay lines, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming the at least first receive beam and the at least second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmission beam, and receiving the uplink transmission using the first receive beam and the second receive beam. BRIEF DESCRIPTION OF DRAWINGS

[0014] In the following, the application will be described in more detail with reference to embodiments and to accompanying drawings, in which:

[0015] Figure 1 Fig. illustrates an example embodiment of a radio access network;

[0016] Figure 2 Fig. illustrates an example embodiment of a phase shifter comprising two switches;

[0017] Figure 3 Fig. illustrates an example embodiment in which a phase shifter is used to implement hybrid beamforming;

[0018] Figure 4A Fig. illustrates an example embodiment of a physical uplink control channel configuration;

[0019] Figure 4B Fig. illustrates an example embodiment of an architecture in which a transmission path comprises hybrid beamforming while a receive path is optimized.

[0020] Figure 4C and Figure 4D Figures illustrate graphs for comparing performance of different use cases; and

[0021] Figure 5 Figures illustrate example embodiments of apparatuses. DETAILED DESCRIPTION

[0022] The following embodiments are exemplary. It should be noted that the terms "an" and "a" as used herein denote "one or more" of something unless context clearly indicates otherwise. Further, terms like "another" and "another" as used herein mean "one or more other" of something, not "one or more but only one." Still further, terms like "another" and "another" as used herein denote "one or more, but not all" of something. As such, the following reference signs are not intended to be limiting.

[0023] As used in this application, the term "circuitry" can refer to all of the following: (a) hardware-only circuitry such as comprising only analog and / or digital circuitry; (b) a combination of hardware circuits and software (and / or firmware), such as (as applicable): (i) a combination of processor(s), or (ii) portions of processor(s) / software including digital signal processors, software, memory, one or more storage devices, and various

[0024] The techniques and methods described herein can be implemented by various means. For example, these techniques can be implemented in hardware (one or more devices), firmware (one or more devices), software (one or more modules), or combinations thereof. For a hardware implementation, the apparatus(es) of an embodiment can be implemented within one or more application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), graphics processing units (GPUs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, a combination thereof, or the like. For firmware or software, the implementation can be carried out through modules of at least one chip set)’s) (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes can be stored in memory units and executed by processors. The memory unit can be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor via any suitable means. Additionally, the components of the systems described herein can be rearranged and / or complemented by additional components in order to facilitate the achievements of the various aspects, etc., described with regard thereto, and they are not limited to the precise configurations set forth in the given figures, as will be appreciated by one skilled in the art.

[0025] Embodiments described herein can be implemented in a communication system, such as in at least one of the following: Global System for Mobile Communications (GSM) or any other second generation cellular communication system, Universal Mobile Telecommunication System (UMTS, 3G) based on basic Wideband Code Division Multiple Access (W-CDMA), High Speed Packet Access (HSPA), Long Term Evolution (LTE), LTE-Advanced, systems based on IEEE 802.11 specifications, systems based on IEEE 802.15 specifications, and / or Fifth Generation (5G) and 5G-Advanced (i.e. 3GPP NR Rel-18 and beyond), mobile or cellular communication systems. Moreover, embodiments described herein can also be implemented in a 6G communication system. However, the embodiments are not limited to the systems given as examples, but a person skilled in the art can apply the solution to other communication systems having the necessary properties.

[0026] Figure 1 Examples depicting simplified system architectures show some elements and functional entities, all being logical units whose implementation can differ from what is shown. Figure 1 The connections in the above-described systems are logical connections; the actual physical connections can differ from what is shown. Figure 1 The systems can comprise additional functional and structural elements besides those shown in the above-described systems. Figure 1 Examples show parts of exemplary radio access networks.

[0027] Figure 1 A terminal device 100 and a terminal device 102 are depicted, which are configured to wirelessly connect with an access node (such as an (e / g)NodeB) 104 providing a cell on one or more communication channels in the cell. The access node 104 can also be referred to as a node. The wireless link from the terminal device to the (e / g)NodeB is referred to as uplink or reverse link, and the wireless link from the (e / g)NodeB to the terminal device is referred to as downlink or forward link. It should be appreciated that the (e / g)NodeB or its functionalities can be implemented by using any node, host, server or access point, etc. entity suitable for such a use. It should be noted that although one cell is discussed in this exemplary embodiment, for simplicity of explanation, in some exemplary embodiments, multiple cells can be provided by one access node.

[0028] The communication system can comprise more than one (e / g)NodeB, in which case the (e / g)NodeBs can also be configured to communicate with one another, over links (wired or wireless) designed for this purpose. These links can be used for signalling purposes. The (e / g)NodeB is a computing device configured to control the radio resources of a communication system it is coupled to. The (e / g)NodeB can also be referred to as a base station, an access point, or any other type of interfacing device including a relay that is capable of operating in a wireless environment. The (e / g)NodeB includes or is coupled to a transceiver. A connection from the transceiver of the (e / g)NodeB to an antenna unit is provided, which establishes bi-directional radio links to user equipment. The antenna unit can include multiple antennas or antenna elements. The (e / g)NodeB is also connected to the core network 110 (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 terminal devices (UEs) to external packet data networks), or a mobile management entity (MME), etc.

[0029] A terminal device (also referred to as UE, user equipment, user terminal, user apparatus, etc.) illustrates a type of apparatus to which resources on the air interface are allocated and assigned, and thus any feature described herein with a terminal device can be implemented with a corresponding apparatus, such as a relay node. An example of such a relay node is a layer 3 relay towards a base station (self-backhauling relay). Another example of such a relay node is a layer 2 relay. Such a relay node can contain a terminal device part and a distributed unit (DU) part. For example, a CU (centralized unit) can coordinate DU operations via an FlAP interface.

[0030] A terminal device can mean a portable computing device, including a wireless mobile communication device operating with or without a subscriber identification module (SIM) or embedded SIM (eSIM), including, but not limited to, the following types of devices: a mobile station (mobile phone), a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and / or touch screen computer, a tablet, a game console, a notebook, and a multimedia device. It should be appreciated that a user device can also be an exclusive, or almost exclusive, uplink only device, an example of which is a camera or video camera that loads images or video clips to a network. A terminal device can also be a device having the ability to operate in an Internet of Things (loT) network, which is a scenario where objects are provided with the ability to transfer data over a network without the need for human-to-human or human-to-computer interaction. A terminal device can also leverage the cloud. In some applications, a terminal device can comprise a small portable device with radio parts, such as watches, headsets or glasses, and the computing is performed in the cloud. A terminal device (or in some embodiments a layer 3 relay node) is configured to perform one or more of the user equipment functions.

[0031] The various techniques described herein can also be applied to a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS can enable the implementation and exploitation of a massive number of interconnected ICT devices (sensors, actuators, processors microcontrollers, etc.) embedded in physical objects. A mobile cyber-physical system, in which the physical system in question has inherent mobility, is a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robots and electronics transported by humans or animals.

[0032] Additionally, although these apparatuses are depicted as single entities, different units, processors and / or memory units (not all shown in the drawings) can be implemented. Figure 1

[0033] ​5G is able to use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than LTE (so-called small cell concept), including a macro sites working in co-operation with smaller stations and employing a variety of radio technologies depending on service needs, use cases and / or available frequency spectrum. 5G mobile communications supports a wide range of use cases and related applications including video streaming, augmented reality, different ways of sharing data and various forms of machine type communication (such as (massive) machine type communications (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 be integrable with existing legacy radio access technologies, such as LTE. At least in the early phase, integration with LTE can be implemented as a system, where macro coverage is provided by LTE and 5G radio interface access comes from small cells by aggregating to LTE. In other words, 5G is planned to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (inter-radio interface operability, such as below 6 GHz - cmWave, below 6 GHz - cmWave - mmWave). One of the concepts considered to be used 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 that have different requirements on latency, reliability, throughput and mobility.

[0034] Current architecture in LTE networks is fully distributed in radio and fully centralized in core network. Low latency applications and services in 5G can require bringing content close to radio, which can lead to local breakout and multi-access edge computing (MEC). 5G enables analytics and knowledge generation at the source of the data. This approach requires leveraging resources that can 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 in close proximity to the cell subscribers for faster response time. Edge computing covers a wide range of technologies such as wireless sensor networks, mobile data acquisition, mobile signature analysis, cooperative distributed peer-to-peer ad hoc networking and processing (also classifiable as local cloud / fog computing and grid / mesh computing), dew computing, mobile edge computing, cloudlet, distributed data storage and retrieval, self-healing networks, remote cloud services, augmented and virtual reality, data caching, Internet of Things (massive connectivity and / or delay critical), critical communications (autonomous vehicles, traffic safety, real-time analytics, time-critical control, healthcare applications).

[0035] The communication system is also able to communicate with other networks, such as a public switched telephone network or the Internet 112, and / or to utilize services provided by them. The communication system can also be able to support the usage of cloud services. For example, at least a part of the core network operations can be carried out as a cloud service (this is depicted in Figure 1 the middle by "cloud" 114). The communication system can further include a central control entity, etc., providing facilities for networks of different operators to cooperate, e.g., in spectrum sharing.

[0036] Edge cloud can be brought closer to the network nodes by utilizing network function virtualization (NFV) and software defined networking (SDN). Using edge cloud can mean that the access node operations are executed, at least partly, in a server, host or node that is operatively coupled to a remote radio head or base station that includes a radio part. It is also possible that the node operations are distributed among a plurality of servers, nodes or hosts. The application of cloudRAN architecture enables RAN real-time functions to be executed in the RAN side (in the Distributed Unit, DU 104) and non-real-time functions to be executed in a centralized manner (in the Centralized Unit, CU 108).

[0037] It should also be understood that the distribution of tasks between core network operations and base station operations can differ from LTE, or even be non-existent. Some other technologies that can be used include, for example, big data and all-IP, which can change the way networks are constructed and managed. 5G (or New Radio, NR) networks are designed to support multiple hierarchies, where MEC servers can be placed between the core and the base station or nodeB (gNB). It should be understood that MEC can also be applied to 4G networks.

[0038] 5G can also utilize satellite communication to enhance or complement the 5G service coverage, for example by providing backhauling or service availability in areas with no terrestrial coverage. Satellite communication can utilize Geostationary Earth Orbit (GEO) satellite systems, but also Low Earth Orbit (LEO) satellite systems (e.g., mega-constellations). Satellites 106 included in a constellation can carry gNBs, or at least part of gNBs, that create the ground cells. Alternatively, satellites 106 can be used to relay signals of one or more cells to the earth. The ground cells can be created by ground-based relay nodes 104, or by gNBs, or parts of gNBs (e.g., DU), located on the ground or in a satellite. Additionally or alternatively, High Altitude Platform Stations (HAPS) systems can be utilized.

[0039] It should be noted that the depicted system is an example of a radio access system, and the system may include multiple (e / g)nodeBs, the terminal equipment may have access to multiple radio cells, and the system may also include other devices, such as physical layer relay nodes or other network elements. At least one of the (e / g)nodeBs may be a home (e / g)nodeB. Additionally, multiple different types of radio cells and multiple radio cells may be provided in the geographical area of ​​the radio communication system. Radio cells may be macrocells (or umbrella cells), which are typically large areas with diameters of tens of kilometers, or smaller cells, such as microcells, femtocells, or picocells. Figure 1 The (e / g)NodeB can provide any type of these cells. A cellular radio system can be implemented as a multi-layered network comprising several types of cells. In some exemplary embodiments, in a multi-layered network, one access node provides one or more cells, and therefore multiple (e / g)NodeBs are required to provide this network structure.

[0040] To meet the need for improved communication system deployment and performance, the concept of "plug and play" (e / g) NodeB was introduced. In addition to the Home (e / g) NodeB (H(e / g) NodeB), networks capable of using "plug and play" (e / g) NodeBs can also include Home NodeB gateways or HNB-GWs. Figure 1 (Not shown in the image). HNB gateways (HNB-GWs) that can be installed within a carrier's network can aggregate services from a large number of HNBs back to the core network.

[0041] To enhance capacity and coverage, massive MIMO and beamforming techniques can be considered useful technologies for achieving these goals. Additionally, phased array antennas can form a baseline to implement those techniques. For example, beamforming (where multiple rows of antenna elements work together to create a high-gain signal) can be used to enhance coverage, and mMIMO utilizes multiple antenna arrays (which can also be subarrays) to provide spatial diversity to improve signal quality by using multiple paths for the same signal, or to provide increased throughput by transmitting multiple spatial layers combined at the receiver. In some example embodiments, beamforming and mMIMO can be deployed together to combine the advantages of both technologies.

[0042] When using antenna arrays, multiple antenna elements are combined to form subarrays. Smaller subarrays (such as a subarray forming a single antenna element), combined with appropriate spacing between them, offer more degrees of freedom for better antenna characteristics, but as the number of subarrays increases, cost and complexity can also increase. For example, cost can increase because each subarray requires a separate transmit-receive (TRX) chain including power amplifiers, low-noise amplifiers, circulators, DACs, ADCs, etc., while complexity can increase because more processing power is needed to calculate the complex weights of each TRX branch of the feed antenna port / subarray. To address this issue, fully digital beamforming can be utilized. The number of TRX chains can be reduced, for example, by adding phase shifters before the selected subarrays or antenna elements, and by applying appropriate phase shifts (by controlling the phase shifters in an analog manner), while still maintaining the ability to manipulate the beam.

[0043] Figure 2 An example embodiment of a phase shifter 200 is illustrated, comprising two switches 210 and 215, which are single-pole four-throw (SP4T) switches connected to a delay line 225. In this example embodiment, switches 210 and 215 are highly linear, high-power switches. The phase shifter 200 also has an input 220, an output 230, and a 2-bit control (CTRL) pin 240. However, it should be noted that although switches 210 and 215 in this exemplary embodiment are high-power SP4T switches, the phase shifter could also be an SPxT switch; that is, the delay line in this exemplary embodiment implements four different phase shifts, but in some other exemplary embodiments, there could be another number (i.e., x) of different phase shifts. The lengths of the different delay lines can depend on the antenna geometry and design. The phase shifter can be controlled from the digital domain via beamforming commands, and therefore the beam direction can be controlled from the digital domain via beamforming commands. The digital domain can be used to manipulate the beam to steer in the correct direction and to determine the correct settings for the analog switches.

[0044] Figure 3 The illustration shows a phase shifter (such as...) Figure 2 The phase shifter 200 shown in the example embodiment is used to achieve hybrid beamforming in the example embodiment by placing the phase shifter precisely in front of the antenna array, which reduces the need for components and also provides cost optimization. Figure 3In an example embodiment of the 312 are part of an antenna subarray 314, and the antenna subarray 314 is included in an antenna column 316. In this example embodiment, the antenna array 310 is included in a radio frequency (RF) front end that has 16 transmitter lines and 16 receiver lines (16T16R). In the RF front end, a phase shifter 320 is just before the antenna array 310. The phase shifter 320 is placed before the antenna subarray 314. In this example embodiment, hybrid beamforming is performed on both the uplink direction and the downlink direction.

[0045] While the use of phase shifters introduces advantages such as optimized cost and enhanced performance, the addition of such switch-based phase shifters can also introduce insertion loss. The insertion loss can impair uplink performance, and, additionally, from a radio resource management (RRM) perspective, the long physical uplink control channel (PUCCH) linked to frequency range 1 (FR1) used for channel state information (CSI) reporting and hybrid automatic repeat request (HARQ) acknowledgement / negative acknowledgement (ACK / NACK) can also introduce system level limitations as it will be supported over multiple symbols. This limitation can limit the performance gain available in the uplink when hybrid beamforming is used. As Figure 3 As shown in an example embodiment of the 312 are part of an antenna subarray 314, and the antenna subarray 314 is included in an antenna column 316. In this example embodiment, the antenna array 310 is included in a radio frequency (RF) front end that has 16 transmitter lines and 16 receiver lines (16T16R). In the RF front end, a phase shifter 320 is just before the antenna array 310. The phase shifter 320 is placed before the antenna subarray 314. In this example embodiment, hybrid beamforming is performed on both the uplink direction and the downlink direction.

[0046] There can also be additional constraints due to the fact that there is a single analog beam available to utilize in the vertical direction at a particular instant in time. For example, the use of up to four narrow beams for hybrid beamforming performance can limit the use of long PUCCH, which can be understood as a PUCCH spread over multiple symbols. Short PUCCH can then be understood as a PUCCH transmitted over one or two symbols. In long PUCCH, the energy is thus spread in the time domain, which helps to increase coverage. Figure 4AAn example embodiment of a PUCCH configuration 400 is illustrated. In this configuration, there are resources allocated for PUCCH (CSI) 410, PUCCH (HARQ) 412, and PUCCH (scheduling request (SR)) 414. For the PUCCH configuration 400 (i.e., long PUCCH), a physical uplink shared channel (PUSCH) 405 is multiplexed in the same slot and / or symbol with hybrid beamforming. Thus, resources are allocated on multiple time scales. The CSI and SR resources are configured using radio resource control (RRC) configuration, and thus, it can be expected that they will be allocated for a long time, e.g., the same length as the entire length of a call for a terminal device served by the cell. This can be because RRC reconfiguration can cause non-negligible delay, and also involves additional control plane load, and thus, is best avoided. During this duration, it can be expected that the best analog beam for a terminal device can change. This can make it difficult to ensure that all terminal devices (whose CSI and / or SR transmissions occur in a given slot) have the same analog beam.

[0047] HARQ ACK / NACK resources are linked to one or more downlink (DL) slots that have ACK / NACK mapped to a current slot in the uplink (UL) direction. In FR1 time division duplex (TDD) (e.g., using slot format DDDSU), there can be four DL and / or special slots that map their PUCCH HARQ ACK / NACK to the same UL slot. If the terminal devices that transmit their HARQ ACK / NACK in a given UL slot will have the same analog beam as their best beam, then the four DL slots that map to the same UL slot for ACK / NACK will also schedule terminal devices on the same analog beam, which can be a constraint that impacts the gain of DL hybrid beamforming.

[0048] In addition to the potential conflict between terminal devices transmitting CSI, SR, HARQ ACK / NACK, there can also be a conflict from the perspective of the PUSCH as to what is optimal. In the UL, the power constraint of the terminal devices can mean that a lower number of physical resource blocks (PRBs) need to be allocated to terminal devices in the cell edge depending on their path loss conditions, which can necessitate an increased need for frequency division multiplexing (FDM) of terminal devices to fully utilize the available system bandwidth. Thus, it would be advantageous to have a solution that optimally addresses the above UL issues, so that the DL hybrid beamforming gain and cost advantage is still preserved.

[0049] In some example embodiments, an uplink-optimized architecture with different beamforming methods for downlink and uplink can be utilized as a method to implement a solution to handle the above-mentioned UL issues, so that the DL hybrid beamforming gain and cost advantage is still preserved. Instead of performing beamforming in the elevation in the analog RF domain, and performing beamforming in the horizontal direction in the digital domain, or vice versa, for both downlink and uplink, the analog beamforming and digital beamforming can be combined in the elevation or azimuth, respectively. Phase shifters including switches and delay lines, such as the phase shifters 320 introduced in the example embodiments of Figure 2 FIG. 4, can be used for this method, as these phase shifters can introduce cost-effective and efficient advantages. For example, in a similar 16T64R architecture, the uplink can remain optimized while the downlink coverage can be enhanced using hybrid beamforming. However, it should be noted that the same method can also be used for other numbers of transmitters (TRX) in higher frequency ranges.

[0050] However, using phase shifters can introduce additional insertion loss that is common for both uplink and downlink directions. Therefore, an uplink-optimized hybrid beamforming architecture can be utilized. Figure 4B An example embodiment is illustrated in which the architecture of the transmit (Tx) path includes hybrid beamforming while the receiver path is optimized. In this example embodiment, there is a single Tx path 410 for one antenna column 420, which can be understood as a complete antenna column. The Tx path 410 includes four phase shifters 430 for four antenna subarrays 425 that enable analog beamforming for downlink beams 440 and 442, which are continuous beams in this example. For example, up to three continuous beams (pointing to different vertical directions) can be applied using the configuration shown in this example embodiment.

[0051] In this example embodiment, for the uplink side, there are four separate Rx paths 412, 414, 416, and 418 for the four antenna sub-arrays. The four Rx paths in this example embodiment each include a switch port connected to the antenna sub-array for which the Rx path is for. This can be achieved by one of the four states of a dedicated switch included in the respective phase shifter 430, e.g., the state of the switch closer to the antenna sub-array, and thus enabling full digital beamforming for the uplink. Thus, the uplink beams 450, 452, 454, and 456 can be received using digital beam detection, and they can be received at one time instant, rather than being received consecutively. It should be noted that the antenna sub-arrays, in this example embodiment four antenna sub-arrays corresponding to the four separate Rx paths 412, 414, 416, and 418, can each define a vertical range within which there can be a flexible number of concurrent receive beams. In other words, a single antenna sub-array is capable of providing multiple concurrent receive beams. The number of receive beams provided by an antenna sub-array depends on the traffic situation. Thus, in this example embodiment, for one polarization, there are four receive paths in the antenna column 420, and these paths can enable full digital beamforming for the uplink in the same way as when using a 64T64R implementation.

[0052] This example embodiment can introduce advantages such as significantly reduced insertion loss, and enabling similar levels of uplink performance compared to using a 64T64R implementation with full digital beamforming. The hardware (HW) architecture introduced in this example embodiment can enable all the features of digital beamforming in the uplink. The use of digital beam detection can also have the advantage that, for mMIMO, the direction of the terminal device and the presence of different beams, such as the Rx beams 450, 452, 454, and 456, can be detected. In this way, the direction of the terminal device and the beam direction can be detected simultaneously in both the elevation and azimuth angles, while also enabling cost savings by reducing the number of Tx array configurations. Another advantage of this example embodiment is that, in dense urban scenarios with high-rise buildings, a 16TX64RX module is implemented for the downlink hybrid beamforming architecture instead of the use of 64T64R.

[0053] Figure 4C Figure 460 is shown, where Figure 4AThe architecture introduced in the example embodiments is compared to the geometric mean of user throughput for a hybrid beamforming 32TRX architecture versus uplink optimized hybrid beamforming for digital beamforming on the uplink. The results illustrate full buffer system simulations with 10 users per cell using a 100 MHz bandwidth carrier at a carrier frequency of 3.5 GHz. The use of full digital beamforming on the uplink is not limited by the restriction of using a single analog beam in the elevation angle, thus allowing users to be frequency division multiplexed without considering their best analog beam. This helps improve PUSCH performance due to improved PRB utilization, which otherwise can be limited due to, for example, an insufficient number of users available on a single analog elevation beam, and does not force the use of wide beams on PUSCH, or narrow analog beams that are not the best beams across users to allow multiplexing of PUSCH and PUCCH reception in a slot.

[0054] Figure 4D The architecture of the example embodiments shown in FIG. 470 is compared to the average number of scheduled users. As already shown by the results in FIG. 470, the use of hybrid beamforming with uplink optimization 472, and a system with 32TRX 474, results in a higher average number of scheduled users than the use of hybrid beamforming without uplink optimization 470, and a system with 32TRX 472. Figure 4B The architecture of the example embodiments shown in FIG. 470 is compared to the average number of scheduled users. As already shown by the results in FIG. 470, the use of hybrid beamforming with uplink optimization 472, and a system with 32TRX 474, results in a higher average number of scheduled users than the use of hybrid beamforming without uplink optimization 470, and a system with 32TRX 472. Figure 4C As shown by the graphs in FIG. 470, with hybrid beamforming with uplink optimization, improved geometric mean performance can be obtained, and the gain percentage increases with the increase of the maximum number of scheduled users. The improvement in gain in system performance can be at least partially because users are not constrained to belong to a single elevation analog beam. Thus, from FIG. 470, the average difference in the number of scheduled users can also be seen, which provides a comparison of scheduled users under the two scenarios, showing that the full digital solution is able to schedule a higher number of users per slot. The average difference in the number of scheduled users increases with the maximum allowed number of scheduled users, because with a smaller number of allowed users, only a limited number of users can be scheduled, regardless of the solution utilized.

[0055] Figure 5The apparatus 500 illustrates an example embodiment of an apparatus, which can be or be comprised in an access node, and can embody the architecture for the above-described beamforming. The apparatus can also be configured to determine transmission and / or reception beams, and to provide beamforming instructions regarding the determined beams, and to transmit and receive transmissions using the determined beams. For example, the apparatus can be a circuitry or chipset suitable for an access node to implement the described embodiments. The apparatus 500 can be an electronic device comprising one or more electronic circuits. The apparatus 500 can comprise a communication control circuitry 500, such as at least one processor, and at least one memory 520 including computer program code (software) 522, wherein the at least one memory and the computer program code (software) 522 are configured to, with the at least one processor, cause the apparatus 500 to perform any of the example embodiments of the access node described above.

[0056] The memory 520 can be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The memory can comprise a configuration database for storing configuration data. For example, the configuration database can store a current list of neighboring cells, and in some example embodiments, the structure of frames used in detected neighboring cells.

[0057] The apparatus 500 can also comprise a communication interface 530 comprising hardware and / or software for realizing communication connectivity according to one or more communication protocols. The communication interface 530 can provide the apparatus with radio communication capabilities for communicating in a cellular communication system. For example, the communication interface can provide a radio interface to terminal devices. The apparatus 500 can also comprise another interface towards a core network, such as a network coordinator apparatus, and / or access nodes of the cellular communication system. The apparatus 500 can also comprise a scheduler 540 configured to allocate resources.

[0058] Although the present application has been described above with reference to example embodiments according to the accompanying drawings, it is clear that the application is not limited thereto, but can be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, but not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. Further, it will be apparent that the described embodiments can but need not be combined with other embodiments.

Claims

1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to perform: determining a transmission beam for a downlink transmission; providing first beamforming instructions to a transmission path comprising a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein along the transmission path the first antenna subarray is connected to a first phase shifter comprising a first switch pair connected using a delay line, and the second antenna subarray is connected to a second phase shifter comprising a second switch pair connected using a delay line, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining for the first antenna subarray at least one receive beam as a first receive beam, and for the second antenna subarray at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming at least the first receive beam and at least the second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first switch pair, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second switch pair; and transmitting the downlink transmission using the transmission beam, and receiving the uplink transmission using the first receive beam and the second receive beam, wherein the first dedicated switch state associated with the first switch pair is a state of a switch included in the first switch pair that is closer to the first antenna subarray, and the second dedicated switch state associated with the second switch pair is a state of a switch included in the second switch pair that is closer to the second antenna subarray.

2. The apparatus of claim 1, wherein the apparatus is further caused to perform beamforming of the first receive beam and the second receive beam in a digital domain.

3. The apparatus of any of the preceding claims, wherein the column of antennas comprises a third subarray of antennas connected to a third phase shifter, the third phase shifter comprising a third pair of switches connected using a delay line, and the third phase shifter is included in the transmission path and is also connected to the digital-to-analog converter, and wherein, the third phase shifter is included in a third receive path, and is further connected to a third analog-to-digital converter included in the third receive path.

4. The apparatus of claim 3, wherein the apparatus is further caused to determine a third receive beam for receiving the uplink transmission, and the second beamforming instructions further comprise instructions for forming the third receive beam.

5. The apparatus of any of the preceding claims, wherein the switch pairs are controlled using their respective control interfaces.

6. The apparatus of any of the preceding claims, wherein at least one switch included in the phase shifter is configured to have four different states.

7. The apparatus of any of the preceding claims, wherein the apparatus is included in an access node.

8. A method comprising: determining a transmission beam for a downlink transmission; providing first beamforming instructions to a transmission path including a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column including at least a first antenna subarray and a second antenna subarray, and wherein, along the transmission path, the first antenna subarray is connected to a first phase shifter including a first switch pair connected using delay lines, and the second antenna subarray is connected to a second phase shifter including a second switch pair connected using delay lines, and wherein the first phase shifter and the second phase shifter are both connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming at least the first receive beam and at least the second receive beam, wherein the first receive path includes the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path includes the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first switch pair, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second switch pair; and transmitting the downlink transmission using the transmission beam, and receiving the uplink transmission using the first receive beam and the second receive beam, wherein the first dedicated switch state associated with the first switch pair is a state of a switch included in the first switch pair that is closer to the first antenna subarray, and the second dedicated switch state associated with the second switch pair is a state of a switch included in the second switch pair that is closer to the second antenna subarray.

9. The method of claim 8, wherein the method further comprises: Beamforming of the first receive beam and the second receive beam is performed in the digital domain.

10. The method of claim 8 or 9, wherein the column of antennas comprises a third subarray of antennas connected to a third phase shifter, the third phase shifter comprising a third pair of switches connected using a delay line, and the third phase shifter is included in the transmission path and is also connected to the digital-to-analog converter, and wherein, The third phase shifter is included in a third receive path, and is also connected to a third analog-to-digital converter included in the third receive path.

11. The method of claim 10, wherein the method further comprises: determining a third receive beam for receiving the uplink transmission, and the second beamforming instructions further comprise instructions for forming the third receive beam.

12. The method of any of claims 8-11, wherein at least one switch included in the phase shifter is configured to have four different states.

13. A non-transitory computer readable medium comprising program instructions stored thereon for performing at least the following: determining a transmit beam for a downlink transmission; providing first beamforming instructions to a transmission path comprising a digital-to-analog converter and an antenna column for forming the transmission beam, the antenna column comprising at least a first antenna subarray and a second antenna subarray, and wherein, along the transmission path, the first antenna subarray is connected to a first phase shifter comprising a first pair of switches connected using delay lines, and the second antenna subarray is connected to a second phase shifter comprising a second pair of switches connected using delay lines, and wherein both the first phase shifter and the second phase shifter are connected to the digital-to-analog converter; determining, for the first antenna subarray, at least one receive beam as a first receive beam, and determining, for the second antenna subarray, at least one receive beam as a second receive beam, for receiving an uplink transmission, wherein the first antenna subarray is capable of providing a first plurality of concurrent receive beams, and the second antenna subarray is capable of providing a second plurality of concurrent receive beams; providing second beamforming instructions to a first receive path and a second receive path, respectively, for forming at least the first receive beam and at least the second receive beam, wherein the first receive path comprises the first phase shifter connected to the first antenna subarray and a first analog-to-digital converter, and the second receive path comprises the second phase shifter connected to the second antenna subarray and a second analog-to-digital converter, and wherein the first receive path is connected to the first phase shifter using a first dedicated switch state associated with the first pair of switches, and the second receive path is connected to the second phase shifter using a second dedicated switch state associated with the second pair of switches; and transmitting the downlink transmission using the transmit beam, and receiving the uplink transmission using the first receive beam and the second receive beam, wherein the first dedicated switch state associated with the first pair of switches is a state of a switch included in the first pair of switches that is closer to the first antenna subarray, and the second dedicated switch state associated with the second pair of switches is a state of a switch included in the second pair of switches that is closer to the second antenna subarray.

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