Transmit reference signals for coexisting cells

Abstract

A reference signal is generated at a cell configured for a first air interface protocol based on a cell identifier of a second air interface protocol. An air interface resource allocation of the first air interface protocol is determined at the cell configured for the first air interface protocol based on the cell identifier of the second air interface protocol. The cell configured for the first air interface protocol transmits the generated reference signal according to the determined air interface resource allocation.

Description

Technical Field

[0001] The present invention relates to co - transmission of reference signals by a cell co - existing with another cell according to different radio interface protocols. Background Art

[0002] This section is intended to provide background or context for the invention set forth in the claims. The description herein may include concepts that could be pursued, but are not necessarily concepts that have been previously conceived or pursued. Thus, unless otherwise indicated herein, the content described in this section is not prior art to the specification and claims in this application and is not admitted to be prior art by virtue of being included in this section.

[0003] Co - existence of radio systems can be provided by spectrum sharing between radio systems. For co - existing radio systems, the radio systems can at least partially use the same frequency band. Thus, some parts of the frequency band may be interference - free, while some other parts of the frequency band may have interference. Therefore, the interference between different parts of the frequency band may be unbalanced, which leads to inaccuracies in channel estimation and measurement on the frequency band and results in sub - optimal link adaptation.

[0004] Spectrum sharing can provide co - existence of New Radio and Long - Term Evolution networks defined by 3GPP specifications. One way to achieve spectrum sharing is static frequency - domain sharing, in which a part of the spectrum allocated to Long - Term Evolution (LTE) is migrated to New Radio (NR). Another way to achieve spectrum sharing is Dynamic Spectrum Sharing (DSS), which has been adopted since Release 15 of the 3GPP specifications, in which NR and LTE can dynamically share the same spectrum.

[0005] The coexistence of LTE and NR networks can lead to interference from NR to LTE and vice versa. Cell Reference Signal Rate Matching (CRS-RM) specified in versions 15 and 16 of the 3GPP NR specification can be used to mitigate the interference. LTE cells transmit cell reference signals (CRS) using fixed assignments of resource elements (REs) defined in time-frequency domain resources. The REs for CRS, i.e., CRS REs, are regularly spaced in the frequency domain and there are four to six time slots in each subframe, depending on the number of antenna ports used for CRS. In CRS-RM, the REs carrying LTE CRS are punctured, and the physical downlink shared channel of NR is rate-matched around the punctured REs. When puncturing is used at the NR cell according to CRS-RM, the NR cell does not transmit on the punctured REs. Thus, CRS-RM protects the NR physical downlink shared channel (PDSCH) from LTE CRS and protects LTE CRS from NR PDSCH. However, from the perspective of LTE, only CRS transmission is protected, while the REs used for user data will experience interference from NR. This interference pattern mismatch causes LTE UEs to perform incorrect channel quality assessments on the REs carrying their data. This may lead to suboptimal link adaptation and degraded demodulation performance in the LTE system. Summary of the Invention

[0006] The scope of protection sought by various embodiments of the present invention is set forth in the independent claims. Embodiments, examples, and features (if any) described in this specification that do not fall within the scope of the independent claims will be construed as useful examples for understanding the various embodiments of the present invention.

[0007] According to a first aspect, there is provided a method, comprising:

[0008] generating a reference signal based on a cell identifier of a second air interface protocol at a cell configured for a first air interface protocol, the cell configured for the first air interface protocol coexisting with at least one cell configured for the second air interface protocol;

[0009] determining, at the cell configured for the first air interface protocol, an air interface resource allocation of the first air interface protocol based on the cell identifier of the second air interface protocol; and

[0010] transmitting, by the cell configured for the first air interface protocol, the generated cell reference signal according to the determined air interface resource allocation.

[0011] According to a second aspect, there is provided an apparatus, comprising:

[0012] A component for generating a reference signal based on a cell identifier of a second air interface protocol at a cell configured for a first air interface protocol, where the cell configured for the first air interface protocol coexists with at least one cell configured for the second air interface protocol;

[0013] A component for determining an air interface resource allocation of a first air interface protocol based on a cell identifier of a second air interface protocol at a cell configured for the first air interface protocol; and

[0014] A component for a cell configured for a first air interface protocol to transmit the generated cell reference signal according to the determined air interface resource allocation.

[0015] According to a third aspect, there is provided an apparatus, the apparatus comprising:

[0016] One or more processors, and a memory storing instructions that, when executed by the one or more processors, cause the apparatus to:

[0017] Generate a reference signal based on a cell identifier of a second air interface protocol at a cell configured for a first air interface protocol, where the cell configured for the first air interface protocol coexists with at least one cell configured for the second air interface protocol;

[0018] Determine an air interface resource allocation of a first air interface protocol based on a cell identifier of a second air interface protocol at a cell configured for the first air interface protocol; and

[0019] Transmit the generated cell reference signal by a cell configured for a first air interface protocol according to the determined air interface resource allocation.

[0020] According to a fourth aspect, there is provided a computer program of a computer-readable program code component, the computer-readable program code component being adapted to at least perform the following:

[0021] Receive a multicast by a receiver wireless device from a multicast transmitter wireless device;

[0022] Generate a reference signal based on a cell identifier of a second air interface protocol at a cell configured for a first air interface protocol, where the cell configured for the first air interface protocol coexists with at least one cell configured for the second air interface protocol;

[0023] Determine an air interface resource allocation of a first air interface protocol based on a cell identifier of a second air interface protocol at a cell configured for the first air interface protocol; and

[0024] The cell configured for the first air interface protocol transmits the generated cell reference signal according to the determined air interface resource allocation.

[0025] According to a fifth aspect, a non-transitory computer-readable medium is provided, including program instructions for causing a device to at least perform the following:

[0026] At a cell configured for a first air interface protocol, generate a reference signal based on a cell identifier of a second air interface protocol, and the cell configured for the first air interface protocol coexists with at least one cell configured for the second air interface protocol;

[0027] At a cell configured for a first air interface protocol, determine an air interface resource allocation for the first air interface protocol based on a cell identifier of a second air interface protocol; and

[0028] The cell configured for the first air interface protocol transmits the generated cell reference signal according to the determined air interface resource allocation.

[0029] One or more of the above aspects may include at least some features from the following list:

[0030] - At a cell configured for a first air interface protocol, determine a resource allocation based on reserving resource elements for the generated cell reference signal.

[0031] - The cell configured for the first air interface protocol transmits the generated cell reference signal on the reserved resource elements.

[0032] - At a cell configured for a first air interface protocol, perform rate matching of user data destined for a user equipment of the cell configured for the first air interface protocol to resource elements adjacent to the resource elements reserved for the generated cell reference signal.

[0033] - At a cell configured for a first air interface protocol, determine a cell identifier for a cell configured for a second air interface protocol based on at least one of the following

[0034] - A signaling procedure with one or more cells configured for the second air interface protocol;

[0035] - A signaling procedure with a centralized network entity for distributing cell-specific cell identifiers;

[0036] - A configuration determined by an operation and maintenance system; and

[0037] - Information on cell identifiers used by one or more cells configured for the second air interface protocol.

[0038] - Determine air interface resource allocation based on information for allocating cell reference signals of at least one cell configured for a second air interface protocol among cells configured for a first air interface protocol.

[0039] - The first air interface protocol is New Radio (NR), the second air interface protocol is Long Term Evolution (LTE), and the cell identifier is a physical cell identifier for LTE.

[0040] At least some embodiments facilitate interference mitigation between different air interface protocols coexisting on the same air interface resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] For a more complete understanding of example embodiments of the present invention, reference is now made to the following description taken in conjunction with the accompanying drawings in which:

[0042] Figure 1 A portion of an exemplary wireless communication access network according to at least some embodiments of the present invention is shown;

[0043] Figure 2a An example of coexistence of LTE and NR according to at least some embodiments is illustrated;

[0044] Figure 2b An example of resource allocation for coexisting LTE and NR according to at least some embodiments is illustrated;

[0045] Figure 3 An example of a method according to at least some embodiments is illustrated;

[0046] Figure 4 An example of a sequence according to at least some embodiments of the present invention is illustrated; and

[0047] Figure 5 A block diagram of an apparatus according to at least some embodiments is illustrated. DETAILED DESCRIPTION

[0048] The following embodiments are exemplary. Although the present specification may refer to "one", "a", or "some" embodiments in several places, this does not necessarily mean that each such reference refers to the same (multiple) embodiment, or that the feature applies only to a single embodiment. Individual features of different embodiments may also be combined to provide other embodiments.

[0049] The use of ordinal terms such as "first", "second", "third", etc. to modify the described features in the claims and the specification does not in itself imply any priority, precedence or order of one described feature over another, nor does it imply a chronological order of acts of performing a method, but is merely used as a label to distinguish one described feature having a certain name from another described feature having the same name (but using an ordinal term), thereby distinguishing the described features.

[0050] There is provided to generate a reference signal based on a cell identifier of a second air interface protocol at a cell configured for a first air interface protocol. At a cell configured for a first air interface protocol, an air interface resource allocation of the first air interface protocol is determined based on the cell identifier of the second air interface protocol. The cell configured for the first air interface protocol transmits the generated reference signal according to the determined air interface resource allocation. Since the cell identifier of the second air interface protocol is used to determine the air interface resource allocation of the first air interface protocol and generate a cell reference signal, a receiver for the second air interface protocol can locate the reference signal from the transmission of the cell configured for the first air interface protocol, identify that the reference signal is compatible with the second air interface protocol, and use the reference signal for various measurements such as channel estimation and estimation of interference + noise variation. In this way, interference mitigation between different air interface protocols coexisting on the same air interface resources is achieved in a mutually compatible manner.

[0051] The cell identifier may be a physical layer identifier of the cell, i.e., a physical cell identifier (physical cell ID). The physical cell ID may be for an LTE radio interface. The physical cell identifier may be used to generate a resource grid of resource elements (REs) including a cell reference signal (CRS). Therefore, the RE position of the cell-specific reference signal (CRS) is affected by the physical cell ID. In addition, the physical cell ID may be used to generate a pseudo-random sequence to scramble a downlink signal transmitted by a cell (such as an NR cell or an LTE cell).

[0052] The air interface protocol refers to the communication protocol for communication devices over the air interface. The air interface protocol can be a physical layer protocol. The air interface protocol can be part of an air interface protocol stack according to radio interface technology, such as an LTE radio interface or a New Radio (NR) radio interface. The physical layer protocol converts the transport channel from a higher protocol layer medium into a physical signal transmitted over the physical medium (i.e., the air interface). The air interface protocol defines the physical layer resources or resource elements (REs) on the physical medium (i.e., the air interface), the location of the resources, and the content of the resources. REs can be defined in the time-frequency domain. An example of the time-frequency domain definition is that an RE can be defined by a combination of subcarrier frequency and symbol number. Examples of air interface protocols include LTE and NR defined by 3GPP specifications. NR is also known as 5G NR or 5G. LTE is also known as E-UTRAN (Evolved Universal Terrestrial Radio Access Network), and its further development is called LTE-Advanced. In an example of the content of the resources, the physical layer protocol can define REs for one or more synchronization signals and reference signals over the air interface. Synchronization signals are physical layer signals, and they need to be identified by UEs accessing the cells of the radio network. In LTE, the synchronization signals are located at the center of the carrier bandwidth, which makes them easy to find. In 5G NR, the synchronization signals are part of the Synchronization Signal / Physical Broadcast Channel (SS / PBCH) block (also known as the synchronization signal block, SSB). These SS / PBCH blocks can be located at multiple positions across the entire carrier bandwidth and are broadcast periodically in different beams and at different times as symbols defined in the radio frame. Reference signals are physical layer signals used to measure the received signal power. In LTE, the cell-specific reference signal (CRS) is used to deliver a reference point for the downlink power to the UE. The CRS is carried by multiple specific resource elements in each time slot, and the location of the resource elements is specifically determined by the antenna configuration.

[0053] It should be noted that although some embodiments are described using LTE and NR as examples of coexisting air interface protocols, these examples can also be applied to other air interface protocols.

[0054] Air interface resource allocation for an air interface protocol (or also referred to hereinafter as resource allocation) may include physical layer resources, or resource elements (REs) and the location of the resources on the physical medium (i.e., the air interface). In one example, the resource allocation may be a resource grid. The resource allocation may include data REs for the communication of downlink and / or uplink user data, and REs for carrying the CRS, i.e., CRS REs. Examples of data REs may include REs carrying physical downlink shared channel (PDSCH) traffic. Coexisting radio systems, such as NR and LTE, may have at least partially conflicting resource allocations. Thus, the REs of the resource allocation define at least partially overlapping resources on the air interface, whereby the resource allocation has conflicting REs. According to at least some embodiments, when radio systems (e.g., NR cells and LTE cells) coexist, the resource elements at the interfering radio system (e.g., an NR cell) may be reserved for the transmission of reference signals or virtual reference signals of other radio systems (e.g., LTE). The virtual reference signal may be known to the UE, e.g., the virtual reference signal may be the LTE CRS known to the LTE UE. The virtual reference signal transmitted by the interfering radio system enables the UE served by the interfered radio system to improve the interference + noise estimation while reducing the interference (removal) of the interfering radio system on the conflicting REs. It should be noted that appropriate interference + noise estimation may also be replaced by random data or repetition of REs instead of the virtual reference signal.

[0055] Rate matching of user data (e.g., the transport block (TB) containing PDSCH user data) refers to the process of selecting the TB size or the coded bits to match the available resources for transmission (subject to modulation and coding rate constraints). The definition of the available transmission resources takes into account the reserved resources in the time / frequency resource grid allocated to carry user data. The symbols carrying useful information created by the modulation process are then assigned to the time / frequency grid resources allocated to the user and rate matched around the reserved REs / resources / signals.

[0056] It should be noted that, hereinafter, the term "virtual" in the claims and the specification is used to modify the described features as labels to distinguish the described features from each other and to help distinguish the novel features in the described embodiments. For example, a virtual RE, such as a virtual CRS RE, may refer to an RE that is reserved and used for transmitting a virtual reference signal. For example, a virtual reference signal (such as a virtual CRS or a virtual LTE CRS) may be a reference signal that is transmitted according to one air interface protocol (such as LTE) but by another air interface protocol (such as NR). The virtual reference signal makes a cell (such as an NR cell) appear to a receiver device (such as an LTE UE served by an LTE cell) as a cell of another air interface protocol (such as LTE). For example, a virtual cell identifier (such as a virtual PCI or a virtual LTE PCI) may refer to a cell identifier, such as a PCI, that is used to determine the virtual reference signal. Figure 1 illustrates an example of a simplified system architecture that shows only some of the elements and functional entities, all of which are logical units and whose implementation may be different from that shown. Figure 1 The connections shown in are logical connections; the actual physical connections may be different. It will be apparent to those skilled in the art that the system generally also includes other functions and structures in addition to Figure 1 the functions and structures shown in.

[0057] However, the present embodiment is not limited to the system given as an example, but those skilled in the art can apply this solution to other communication systems provided with the necessary attributes.

[0058] Figure 1 The example of shows a part of an exemplary radio access network.

[0059] Figure 1 shows user equipments 100 and 102, which are configured to make a wireless connection with an access node (such as an (e / g)NodeB (Node B)) 104 that provides a cell on one or more communication channels of 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 using any entity such as a node, host, server, or access point suitable for this purpose. The access node provides access by means of communication of radio frequency (RF) signals and can be called a radio access node. It should be understood that the radio access network may include more than one access node, whereby a handover of the wireless connection of the user equipment from a cell of one access node (such as the source cell of the source access node) to another cell of another node (such as the target cell of the target access node) can be performed.

[0060] 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. The (e / g)NodeB is a computing device that is configured to control the radio resources of the communication system to which it is coupled. The NodeB can also be referred to as a base station, access point, access node, or any other type of interface device, including a relay station 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 is provided to an antenna unit that establishes a two-way radio link with a user equipment. The antenna unit can include multiple antennas or antenna elements. The (e / g)NodeB is further connected to a 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 a connection between the user equipment (UE) and an external packet data network, or a Mobility Management Entity (MME), etc.

[0061] A user equipment (also referred to as UE, user equipment, user terminal, terminal device, wireless device, communication device, 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 device, such as a relay node. An example of such a relay node is a Layer 3 relay (self-backhaul relay) towards a base station.

[0062] A user generally refers to a portable computing device, which includes wireless mobile communication devices operating with or without a subscriber identity module (SIM), including but not limited to the following types of devices: mobile stations (mobile phones), smartphones, personal digital assistants (PDAs), cell phones, devices using wireless modems (such as alarm or measurement devices, etc.), laptop computers and / or touchscreen computers, tablet computers, game consoles, notebooks, and multimedia devices. It should be understood that the user equipment can also be a device with almost only an uplink, examples of which are cameras or video cameras that load images or video clips onto 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 ability to transfer data for objects is provided through the network without human-to-human or human-machine interaction. The user equipment can also utilize the cloud. In some applications, the user equipment can include small portable devices with a radio part (such as watches, headphones, or glasses), and the computing is performed in the cloud. The user equipment (or a third-layer relay node in some embodiments) is configured to perform one or more of the user equipment functions. The user equipment can also be referred to as a subscriber unit, mobile station, remote terminal, access terminal, user terminal, or user equipment (UE), to name just a few names or devices.

[0063] 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 the implementation and utilization of a large number of interconnected ICT devices (sensors, actuators, processor microcontrollers, etc.) embedded in physical objects at different locations. Mobile cyber-physical systems (where the physical systems discussed have inherent mobility) are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robots and electronic products carried by humans or animals.

[0064] In addition, although the device has been depicted as a single entity, different units, processors, and / or memory units can be implemented (not all shown in Figure 1 ).

[0065] 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 operate in cooperation with smaller base stations and employ various radio technologies, depending on service requirements, use cases, and / or available spectrum. 5G mobile communications supports a wide range of use cases and related applications, including video streaming, augmented reality, different ways of data sharing, and various forms of machine-type applications (such as (massive) machine-type communications (mMTC), including vehicle safety, different sensors, and real-time control. 5G is expected to have multiple radio interfaces, namely below 6 GHz, centimeter waves, and millimeter waves, and can also be integrated with existing traditional radio access technologies (such as LTE). At least in the early stages, the integration with LTE can be implemented as a system where macro coverage is provided by LTE, while 5G radio interface access comes from small cells aggregated to LTE. In other words, 5G plans to support both inter-RAT operability (such as LTE-5G) and inter-RI operability (operability between radio interfaces, such as below 6 GHz - centimeter waves, below 6 GHz - centimeter waves - millimeter waves). One of the concepts considered in 5G networks is network slicing, where multiple independent and dedicated virtual sub-networks (network instances) can be created within the same infrastructure to run services with different requirements for latency, reliability, throughput, and mobility.

[0066] The current architecture in LTE networks can be fully distributed in the radio and fully centralized in the core network. The low-latency application and service requirements in 5G bring content closer to the radio, which leads to 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, cooperative distributed peer-to-peer ad hoc networks, 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 analytics, time-critical control, healthcare applications).

[0067] The communication system can also communicate with other networks such as the public switched telephone network or the Internet 112, or utilize the services provided by them. The communication network may also be able to support the use of cloud services. For example, at least a part of the core network operation can be performed as a cloud service (which is depicted by the "cloud" 114 in Figure 1 ). The communication system may also include a central control entity and so on, providing facilities for the networks of different operators to cooperate in, for example, spectrum sharing.

[0068] The edge cloud can be brought into the radio access network (RAN) by leveraging network function virtualization (NVF) and software defined network (SDN). Using the edge cloud may mean that access node operations are performed at least partly in servers, hosts or nodes coupled to the operation of remote radio heads or base stations including radio parts. The node operations may also be distributed among multiple servers, nodes or hosts. The application of the cloud RAN architecture enables the real-time functions of the RAN to be executed on the RAN side (in the distributed unit DU 104), while the non-real-time functions can be executed in a centralized manner (in the centralized unit CU 108).

[0069] It should also be understood that the distribution of the labor force between the core network operation and the base station operation may be different from that of LTE or even non-existent. 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. The 5G (or new radio, NR) network is designed to support multiple hierarchies, where the MEC server 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.

[0070] 5G can also utilize satellite communication to enhance or supplement the coverage of 5G services - for example, by providing backhaul. Possible use cases are to provide service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or passengers in vehicles, or to ensure the service availability of critical communications and future railway / marine / aviation communications. Satellite communication can utilize the geostationary orbit (GEO) satellite system, but can also utilize the low Earth orbit (LEO) satellite system, especially the mega constellation (a system in which hundreds of (nano) satellites are deployed). Each satellite 106 in the mega constellation can cover several satellite-supported network entities that create ground cells. The ground cells can be created by ground relay nodes 104 or by gNBs located on the ground or in satellites.

[0071] It will be apparent to those skilled in the art that the described system is merely an example of 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.

[0072] In addition, the (e / g)NodeB or base station may also be split into: a radio unit (RU) including a radio transceiver (TRX) (i.e., a transmitter (TX) and a receiver (RX)); a distributed unit (DU) that can be used for so-called layer 1 (L1) processing and real-time layer 2 (L2) processing; and a centralized unit (CU) or central unit that can be used for non-real-time layer 2 and layer 3 (L3) processing. Such a split can make the CU centralized relative to the cell site and the DU, while the DU can be more distributed and can even be pre-reserved at the cell site. The CU and the DU together may also be referred to as the baseband or baseband unit (BBU). The RU and the DU may also form a radio access point (RAP). A cloud computing platform may also be used to run the CU or the DU. The CU may run in a cloud computing platform (vCU, virtualized CU). In addition to the vCU, there may also be a virtualized DU (vDU) running in the cloud computing platform. In addition, there may also be a combination where the DU may use a so-called bare-metal solution, such as a system-on-chip (SoC) solution of an application-specific integrated circuit (ASIC) or a customer-specific standard product (CSSP). It should also be understood that the distribution of labor between the above-mentioned base station units, or between different core network operations and base station operations, may be different.

[0073] The open radio access network defined by the Open Radio Access Network Alliance, i.e., O-RAN, refers to the concept that enables RAN elements between different vendors to interoperate through a set of defined interfaces. Thus, for example, the O-RAN architecture enables baseband and radio unit components from different vendors to operate together. Although cloud RAN and open RAN (ORAN or O-RAN) may be related and may often be discussed together, they can also be regarded as different technologies, and one can be applied without the other. Open RAN, for example, defines open interfaces between network elements, while cloud RAN, for example, can virtualize the baseband and separate the baseband hardware and software.

[0074] In addition, in a geographical area of a radio communication system, multiple different types of radio cells as well as multiple radio cells can be provided. A radio cell can be a macro cell (or umbrella cell), which is a large cell typically having a diameter of up to several tens of kilometers, or they can be smaller cells such as micro cells, femto cells or pico cells or so-called small cells. Figure 1 The (e / g)NodeB 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.

[0075] To meet the need to improve the deployment and performance of a communication system, the concept of "plug-and-play" (e / g)NodeB can also be introduced. Generally, a network capable of using "plug-and-play" (e / g)NodeB includes, in addition to a home (e / g)NodeB (H(e / g)NodeB), a home NodeB gateway or HNB-GW ( Figure 1 not shown in the figure). The HNB gateway (HNB-GW), which is usually installed in an operator's network, can aggregate traffic from a large number of HNBs to the core network.

[0076] Figure 2a Illustrated is the coexistence of LTE and NR according to at least some embodiments. The NR gNB 202 is configured to operate on the same frequency band, such as the 2.1 GHz LTE band, together with one or more LTE eNBs 204, 206. Thus, the resource allocation of the NR gNB and the LTE eNBs can at least partially overlap. In the illustrated example, the UE 208 is served by a cell (NR cell) provided by the gNB, while another UE 210 is served by a cell (LTE cell) provided by the eNB 206. The UE 208 served by the NR cell can be referred to as an NR UE, while the UE 210 served by the LTE cell can be referred to as an LTE UE. The UE is located at the cell edge of the NR cell and the LTE cell. At this location, the LTE UE may experience interference from the NR cell, while the NR UE may experience interference from the LTE cell. In Figure 2a the example illustrated in the figure, the LTE UE is served by the LTE cell through the serving link 211 and receives CRS transmissions according to the resource allocation performed at the LTE cell. However, the LTE UE also receives interference from the NR cell through the interference pattern link 212 because the interference pattern link may have resource elements that conflict with the serving link of the LTE UE. In Figure 2aIn another example illustrated herein, the NR UE is connected to the NR cell via a punctured serving link 214 and receives PDSCH data rate-matched to REs at the NR cell via the serving link 211, where these REs are around or near the REs of the NR cell that conflict with the CRS REs of the LTE cell. Thus, the positions of the CRS REs of the LTE cell have been used at the NR cell to puncture the resource allocation of the NR cell at the REs that conflict with the CRS REs. In addition, rate matching is used at the NR cell so that the NR UE 208 can receive the NR PDSCH from the NR cell without receiving the punctured REs. Since the PDSCH data is rate-matched around or near the punctured REs, the CRS 216 from the LTE cell does not interfere with the PDSCH data from the NR cell. It should be noted that in the Figure 2a scenario illustrated herein, it is possible that the LTE UE and the NR UE are positioned such that the NR cell may interfere with the CRS of one or more other LTE cells, where these other LTE cells may be served by the same or different eNBs 204, 206. In this case, the NR can puncture the REs of the NR cell that conflict with the CRS REs of one or more other cells from its resource allocation. In this way, the CRS from the other LTE cells does not interfere with the PDSCH data from the NR cell. On the other hand, when the NR cell punctures the REs that conflict with any CRS REs of the LTE cell, the interference from the NR cell is mitigated. The puncturing can be performed by the scheduler of the gNB based on a rate matching (RM) algorithm. The RM can be for puncturing the CRS REs of the LTE cell to avoid interference with receiving the CRS at the UE. It should be noted that the NR gNBs can be connected via the X2 / Xn interface for network-assisted interference cancellation and suppression (NAICS) and rate matching with the (multiple) LTE eNBs 204, 206. In this way, at least the information indicating the allocation of the cell reference signal of the LTE cell can be transmitted to the NR gNB for puncturing and rate matching of the CRS. Examples of the information indicating the allocation of the cell reference signal include at least the symbol number and the subcarrier. Release 12 of the LTE specification supports NAICS. In NAICS, the serving eNB shares the information of the interference signals from the surrounding eNBs with its UE, and in turn, these UEs can use the shared information to cancel and suppress the interference signals.

[0077] It should be noted that the truncation performed at the NR cell may cause a mismatch in the interference pattern between the resource elements (REs) used for data transmission and channel estimation, and result in a degradation of the demodulation performance on the LTE UE side. To mitigate this situation, in an example according to at least some embodiments, the truncated resource elements at the NR cell can be used to transmit LTE CRS or virtual LTE CRS. The virtual LTE CRS transmitted by the NR cell enables the LTE UEs served by the LTE cell to mitigate the interference of the conflicting REs of the NR cell on the REs of the LTE cell. The mitigation can at least refer to the mitigation of the interference pattern mismatch and the mitigation of the interference in the demodulation of the conflicting REs.

[0078] Figure 2b illustrates resource allocation for coexisting LTE and NR according to at least some embodiments. Referring to Figure 2a and Figure 2b to describe this resource allocation. This resource allocation is illustrated by a resource grid 226 including REs in the frequency-time domain. The resource grid can illustrate the resource allocation on the truncated serving link 214. The REs include virtual CRS REs 224 and the REs 222 around or near the virtual CRS REs 224, and the virtual CRS REs 224 are the REs that conflict with the CRS REs of the LTE cell. The virtual CRS REs are reserved for transmitting virtual LTE CRS by the NR cell. In this way, the virtual CRS REs are regarded by the LTE UEs served by the LTE cell provided by the eNB 206 as the CRS from neighboring LTE cells, and the LTE UEs can use the CRS to mitigate the interference from the NR cell on the LTE REs conflicting with the NR REs.

[0079] Figure 3 illustrates an example of a method according to at least some embodiments. This method provides interference mitigation between different air interface protocols coexisting on the same air interface resource. This example can be performed by, for example, a scheduler or a gNB at the interfering transmitter to achieve LTE and NR coexistence. Stage 302 includes generating a reference signal based on the cell identifier of the second air interface protocol at the cell configured for the first air interface protocol, where the cell configured for the first air interface protocol coexists with at least one cell configured for the second air interface protocol. Stage 304 includes determining the air interface resource allocation of the first air interface protocol based on the cell identifier of the second air interface protocol at the cell configured for the first air interface protocol. Stage 306 includes transmitting the generated cell reference signal by the cell configured for the first air interface protocol according to the determined air interface resource allocation.

[0080] In one example, in stage 302, the first air interface protocol is NR and the second air interface protocol is LTE. A reference signal, LTE CRS, is generated based on the LTE PCI at the NR cell. The LTE CRS is transmitted on the REs of the NR cell. The NR REs for the LTE CRS are determined based on the CRS pattern used by the LTE cell. In this way, the NR cell appears as an interfering LTE cell to the LTE UEs served by the LTE cell, and the LTE UEs can mitigate the interference from the NR cell. This enables improved accuracy in interference estimation, channel estimation, and measurement for LTE.

[0081] In one example, stage 304 includes rate matching of PDSCH data destined for an NR UE at the NR cell to REs adjacent to the REs reserved for the virtual LTE CRS. The REs reserved for the virtual LTE CRS may be truncated.

[0082] It should be noted that in stage 306, since the interfering transmitter (e.g., the NR cell) uses the cell identifier of the second air interface protocol to generate the reference signal and determine the resource allocation, the cell reference signal transmitted from the interfering transmitter may appear as a cell according to the second air interface protocol to the receiver (e.g., the UE).

[0083] It should be noted that in stage 302, since the generated cell reference signal is configured for an air interface protocol different from the interfering transmitter (e.g., the NR cell), the generated cell reference signal can be referred to as a virtual reference signal, and the interfering cell can be a virtual cell of the second air interface protocol, such as a virtual LTE cell. Based on the virtual reference signal, the receiver (e.g., the LTE UE) can determine the power of the reference signal and apply interference mitigation techniques defined in, for example, LTE (e.g., using the LTE NAICS framework). Referring to examples of interference mitigation in LTE, two types of receivers can be envisioned for the LTE UE. In both of these receivers, in addition to the channel, the LTE UE can also estimate the noise + interference variance.

[0084] o (1) A receiver of the interference cancellation (IC) type 1, where the channel response is estimated sequentially, where the channel of the neighboring cell is estimated first, then the estimated neighboring cell signal is subtracted from the received signal, followed by the serving cell channel estimation.

[0085] ο(2)IC type 2 receiver, in which a joint channel estimation method such as minimum mean square error estimation (MMSE), or maximum likelihood estimation (MLE), or least squares estimation (LSE), DFT-based channel estimation, or message passing method is used. The message passing method is described in Yan Zhu et al., "A Message-Passing Approach for Joint Channel Estimation, Interference Mitigation, and Decoding" (IEEE Transactions on Wireless Communications, Vol. 8, No. 12, December 2009).

[0086] An example of the signals received at the LTE UE from an LTE serving cell and an NR interfering cell can be written as

[0087] y i = h i P i + βh I，i P I，i + n i , i = 1,..., N CRS ,

[0088] where:

[0089] - h i is the composite channel coefficient (including attenuation, path loss, etc.) between the serving LTE cell and the LTE UE,

[0090] - P i is the LTE QPSK transmission pilot symbol transmitted using the energy per resource element (EPRE) of the LTE base station,

[0091] n i is the additive noise,

[0092] β is the CRS / data RE power ratio; typically 1,

[0093] N CRS is the total number of CRS REs in the LTE subframe,

[0094] h I，i is the composite channel coefficient between the interfering NR cell and the LTE UE,

[0095] P I，i is the CRS ("pilot") of the virtual LTE cell (transmitted from the interfering NR cell using the energy per resource element of the NR base station used for the PDSCH channel). If the LTE UE knows the parameters of the interfering NR cell, it can internally generate P I，i。

[0096] Then, the LTE UE interfered by the virtual LTE cell can improve its channel estimation. For example, for an IC receiver type 1, the channel estimation can be written as

[0097]

[0098] wherein the UE first estimates the channel of the interfering party and then removes the estimated interference signal from the received signal y i and then applies zero-forcing channel estimation (multiplied by ) to obtain the channel coefficients. ) to obtain the channel coefficients.

[0099] Finally, the LTE UE can estimate the variance of the noise + interference as

[0100]

[0101] Therefore, this method helps the LTE UE with IC capabilities to have an accurate estimation of the channel coefficients of the interference and an accurate estimation of the channel of the serving cell which results in a more accurate estimation of the noise + interference variance.

[0102] In an example according to at least some embodiments, stage 304 includes determining a resource allocation based on reserving resource elements for the generated cell reference signal at the cell configured for the first air interface protocol; and transmitting the generated cell reference signal by the cell configured for the first air interface protocol on the reserved resource elements. In one example, the NR cell can transmit the LTE CRS on the reserved REs. The LTE CRS can be referred to as a virtual LTE CRS because it is transmitted by the NR cell. Thus, the virtual LTE CRS is an LTE-compliant signal that complies with the rules set in the current LTE network. The reserved REs can be defined as truncated REs or rate-matched REs, whereby the LTE UE can receive PDSCH data from the REs surrounding the reserved REs. It should be noted that the truncated REs are not considered when calculating the transport block size, while the rate-matched REs are considered.

[0103] In one example, stage 304 includes: resource elements for the generated cell reference signal can be reserved based on the cell identifier of the second air interface protocol for resource allocation of the first air interface protocol. The cell identifier can determine on which resource elements of the resource allocation or resource grid the cell reference signal is transmitted. In one example, the cell identifier of the second air interface protocol can be an LTE PCI, and the LTE physical cell identifier is used to determine on which REs the LTE CRS is transmitted. Since the LTE CRS is transmitted by an interfering radio system (e.g., by an NR cell), the LTE CRS can be referred to as a virtual LTE CRS.

[0104] In one example, in stage 304, resource elements for the generated reference signal can be reserved based on truncating the reserved resource elements and performing rate matching of user data to resource elements adjacent to the truncated resource elements. The truncation pattern of the resource elements can be determined based on the generated cell reference signal. It should be noted that the truncation pattern can be specific to the number of antenna ports of the resource elements in the first cell. The rate-matched resource elements carrying user data can be received by a UE served by a cell according to the first air interface protocol, while a UE served by a cell according to the second air interface protocol can receive the generated reference signal. In this way, the cell according to the first air interface protocol appears to the UE as a cell according to the second air interface protocol. Since the cell reference signal is according to the second air interface protocol, the UE can use the cell reference signal to mitigate interference from the first cell.

[0105] In an example according to at least some embodiments, stage 304 includes, at a cell configured for the first air interface protocol, performing rate matching of user data destined for a user equipment of the cell configured for the first air interface protocol to resource elements adjacent to the resource elements reserved for the generated cell reference signal. Since the user data is rate-matched to adjacent resource elements, the resource elements reserved for the generated cell reference signal are claimed not to be used for transmitting data to a UE served by the cell configured for the first air interface protocol. In one example, the rate matching can be performed by truncating or repeating transport channel data bits (e.g., PDSCH data bits) around or near the resource elements reserved for the generated cell reference signal (e.g., virtual LTE CRS RE).

[0106] In an example according to at least some embodiments, stage 302 includes, at a cell configured for the first air interface protocol, determining the cell identifier configured for the second air interface protocol based on at least one of the following:

[0107] - a signaling procedure with a centralized network entity for distributing cell-specific cell identifiers;

[0108] - Configuration determined by the operation and maintenance system; and

[0109] - Information on cell identifiers used by one or more cells configured for the second air interface protocol.

[0110] In one example, stage 302 includes: The signaling procedure with the centralized network entity may include a request for a cell identifier configured for the second air interface protocol from a cell configured for the first air interface protocol or a base station hosting the cell to the centralized network entity. Preferably, the centralized network entity may determine a cell identifier configured for the second air interface protocol that is not assigned to any cell configured for the second air interface protocol, and send the determined cell identifier in response to the request. In this way, the cell identifier configured for the second air interface protocol may be different from any cell identifier that has been assigned to a cell configured for the second air interface protocol. In one example, the signaling procedure may be performed via the X2 / Xn interface.

[0111] In one example, stage 302 includes: Information on cell identifiers used by one or more cells configured for the second air interface protocol may be obtained based on information indicating the one or more cell identifiers used received from the one or more cells configured for the second air interface protocol. In this way, the cell identifier configured for the second air interface protocol may be determined to be different from any used cell identifier of the second air interface protocol. In one example, information on the used cell identifier may be received via the X2 / Xn interface.

[0112] In one example, stage 302 includes: Information indicating the used cell identifier may be received by a signaling procedure between a cell configured for the first air interface protocol and one or more cells configured for the second air interface protocol. In one example, the signaling procedure may be performed via the X2 / Xn interface.

[0113] In one example, stage 302 includes: Information indicating the used cell identifier received at a cell configured for the first air interface protocol may be used to establish a list of used cell identifiers for the second air interface protocol, and the cell identifier configured for the second air interface protocol may be determined based on the list. Then, the cell identifier configured for the second air interface protocol may be determined to be a cell identifier not included in the list.

[0114] In one example, stage 302 includes: The configuration determined by the operation and maintenance system can be executed by the operator. The OAM can be connected to the base station hosting the cell, whereby the operator can manually configure the cell identifier of the second air interface protocol via the user interface of the OAM.

[0115] In an example according to at least some embodiments, stage 302 includes determining an air interface resource allocation at a cell configured for a first air interface protocol based on information indicating the allocation of a cell reference signal for at least one cell configured for a second air interface protocol. In one example, the information indicating the cell reference signal allocation may indicate the mapping of the cell reference signal according to the second air interface protocol.

[0116] Figure 4 Illustrated is a sequence according to at least some embodiments. This sequence may be executed by a gNB for implementing the coexistence of LTE and NR described with reference to FIG. 2. This sequence is described according to Figure 3 the stages of the method described in, the first air interface protocol is New Radio (NR), and the second air interface protocol is Long Term Evolution (LTE), and the cell identifier is the physical cell identifier for LTE. It should be noted that if DSS is used, the LTE cell may be the same cell as the NR cell.

[0117] Stage 402 includes obtaining, at the NR cell, the physical cell identifier (PCI) for LTE, or a virtual LTE PCI. This PCI may be referred to as a virtual LTE PCI because, according to Figure 3 the method described in, it is used by the NR cell to determine the virtual LTE CRS and RE. The virtual LTE PCI can be determined based on at least one of the following:

[0118] - A signaling procedure with a centralized network entity for distributing cell-specific cell identifiers;

[0119] - A configuration determined by the operation and maintenance system; and

[0120] - Information on cell identifiers used by one or more cells configured for the second air interface protocol.

[0121] In one example, stage 402 includes: The virtual LTE PCI may have the same vshift value as one or more coexisting LTE cells. vshift defines the cell-specific frequency offset of the CRS for the mapping of CRS to RE and is defined in 3GPP TS 36.211 as follows:

[0122] The cell-specific frequency offset is given by given.

[0123] Therefore, the virtual LTE PCI of the NR cell can be selected as any value as long as it gives the same vshift as the serving LTE cell.

[0124] Stage 404 includes: The NR cell and the LTE cell agree on a resource allocation pattern. As a result, the conflict pattern between the REs of the NR cell and the CRS REs is determined. In one example, the NR cell and the LTE cell agree on time slots, bandwidth, vshift[PCI mod 6], CRS ports, etc.

[0125] In one example, the resource allocation pattern of the LTE cell indicates the location of the CRS REs. The location of the CRS REs can be used to reserve the REs at the same location for the NR in the resource allocation pattern. In one example, stage 404 can be performed based on a signaling procedure via the X2 / Xn interface between the gNB providing the NR cell and the eNB providing the LTE cell.

[0126] Stage 406 includes: Configuring one or more LTE UEs for the conflict pattern. In this way, the LTE UEs can know the location of the CRS from the LTE cell and use the CRS, for example, for channel estimation. The LTE NAICS framework can be used to configure the UEs.

[0127] Stage 408 includes: The NR cell generates and transmits a CRS, or a virtual LTE CRS, using the virtual LTE PCI on the same REs as those used by the LTE cell for the CRS. Therefore, according to the conflict pattern known to the LTE UEs. Therefore, the NR cell can use the determined conflict pattern to determine the resource allocation for transmitting the CRS. Therefore, stage 408 can include: Generating the virtual CRS, determining the resource grid including the virtual CRS, and transmitting the virtual CRS according to stages 302 to 306.

[0128] Stage 410 includes: Applying interference mitigation at the LTE UE. The UE can have an IC type 1 or an IC type 2 receiver. In one example, an LTE UE with an IC type 2 receiver can improve its channel estimation by jointly estimating its own channel h i and the channel of the interfering party to improve its channel estimation. In one example, the LTE UE can estimate the noise + interference variance, which accurately reflects the true noise + interference value on the data REs, and use it for link adaptation / channel quality indicator (LA / CQI) feedback. It should be noted that the effective interference power used for CQI feedback calculation depends on the interference mitigation capability of the LTE UE. For very advanced interference cancellation receivers, the effective interference may be close to zero.

[0129] Figure 5Illustrated is an example of a device according to at least some embodiments of the present invention. The device may be a base station, such as a gNB or a part of a base station. The device may host a cell according to an air interface protocol for providing wireless access to UEs within the coverage area of the device.

[0130] The device includes a processor 502 and a transceiver 504. The processor is operatively connected to the transceiver for controlling the transceiver. The device may include a memory 506. The memory may be operatively connected to the processor. It should be understood that the memory may be a separate memory or may be included in the processor and / or the transceiver.

[0131] In one example, the device includes a scheduler 508 operatively connected to the processor. The scheduler may be configured to perform one or more functions described in the examples described herein, including generating reference signals, determining air interface resource allocations, transmitting reference signals according to the air interface resource allocations, and causing one or more of the foregoing.

[0132] According to one embodiment, the processor is configured to control the transceiver and / or perform one or more functions described using the method according to one embodiment.

[0133] Embodiments may be implemented in software, hardware, application logic, or a combination of software, hardware, and application logic. The software, application logic, and / or hardware may reside in the memory or any computer medium. In an example embodiment, the application logic, software, or instruction set is maintained on any of a variety of conventional computer-readable media. In the context of this document, "memory" or "computer-readable medium" may be any medium or component that can contain, store, communicate, propagate, or transport instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0134] In relevant cases, references to "computer-readable storage medium", "computer program product", "specifically embodied computer program", etc., or "processor" or "processing circuit", etc., should be understood to cover not only computers having different architectures such as single / multi-processor architectures and sequencer / parallel architectures, but also dedicated circuits such as field-programmable gate arrays FPGAs, application-specific integrated circuits ASICs, signal processing devices, and other devices. References to computer-readable program code means, computer programs, computer instructions, program indications, instructions, computer code, etc., should be understood to represent software for programmable processor firmware, such as programmable content of a hardware device, as instructions for a processor or configured or configuration settings of fixed-function devices, gate arrays, programmable logic devices, etc.

[0135] Although the above examples describe embodiments of the present invention operating within a wireless device or wireless network, it should be understood that the present invention as described above can be implemented as part of any apparatus that includes circuitry for transmitting and / or receiving radio frequency signals. Thus, for example, embodiments of the present invention can be implemented in a mobile phone, in a base station, in a computer such as a desktop computer or a tablet computer that includes radio frequency communication components (e.g., wireless local area network, cellular radio, etc.).

[0136] In general, various embodiments of the present invention can be implemented in hardware or in a dedicated circuit or in any combination thereof. Although the various aspects of the present invention can be illustrated and described with 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 can 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.

[0137] Embodiments of the present invention can be practiced in various components such as integrated circuit modules, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), microcontrollers, microprocessors, and combinations of these modules. The design of integrated circuits is generally a highly automated process. Sophisticated software tools can be used to transform a logic level design into a semiconductor circuit design for etching and formation on a semiconductor substrate.

[0138] Programs, such as those provided by Synopsys, Inc. of Mountain View, California and Cadence Design of San Jose, California, can automatically route conductors and position components on a semiconductor chip using well-established design rules and a library of pre-stored design modules. Once the semiconductor circuit design is complete, the resulting design in a standardized electronic format (e.g., Opus, GDSII, etc.) can be transferred to a semiconductor manufacturing facility or "fab" for fabrication.

[0139] As used in this application, the term "circuitry" can refer to one or more or all of the following:

[0140] (a) only hardware circuit implementations (e.g., implementations in only analog and / or digital circuitry), and

[0141] (b) combinations of hardware circuits and software, such as, if applicable:

[0142] (i) combinations of (multiple) analog and / or digital hardware circuits with software / firmware, and

[0143] (ii) any part of a (multiple) hardware processor with software (including a (multiple) digital signal processor), software, and a (multiple) memory that work together to enable a device such as a mobile phone or a server to perform various functions), and

[0144] (c) (Multiple) hardware circuits and / or (multiple) processors that require software (such as firmware) to operate, such as a (multiple) microprocessor or a part of a (multiple) microprocessor, but the software may not be present when it is not required for operation.

[0145] This definition of circuitry applies to all uses of the term in this application, including all uses in any claim. As a further example, as used in this application, the term circuitry also encompasses implementations of only hardware circuits or processors (or multiple processors) or a part of a hardware circuit or processor and its (or their) accompanying software and / or firmware. By way of example and as applicable to a particular claim element, the term circuitry also encompasses a baseband integrated circuit or a processor integrated circuit for a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or network devices.

[0146] The foregoing description has provided a complete and informative description of exemplary embodiments of the invention by way of example and not limitation. However, to those skilled in the relevant art, various modifications and adaptations may become apparent when reading in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications to the teachings of the invention will still fall within the scope of the invention.

Claims

1. A method for communication, comprising: At a cell configured for a first air interface protocol, generating a cell reference signal based on a cell identifier of a second air interface protocol, and the cell configured for the first air interface protocol coexists with at least one cell configured for the second air interface protocol; At the cell configured for the first air interface protocol, determining an air interface resource allocation of the first air interface protocol based on the cell identifier of the second air interface protocol; And Transmitting, by the cell configured for the first air interface protocol, the generated cell reference signal according to the determined air interface resource allocation.

2. The method according to claim 1, comprising: At the cell configured for the first air interface protocol, determining the air interface resource allocation based on reserving resource elements for the generated cell reference signal; And Transmitting, by the cell configured for the first air interface protocol, the generated cell reference signal on the reserved resource elements.

3. The method according to claim 2, comprising: At the cell configured for the first air interface protocol, performing rate matching of user data destined for a user equipment of the cell configured for the first air interface protocol to resource elements adjacent to the resource elements reserved for the generated cell reference signal.

4. The method according to any one of claims 1 to 3, comprising: At the cell configured for the first air interface protocol, determining the cell identifier of the cell configured for the second air interface protocol based on at least one of the following - A signaling procedure with one or more cells configured for the second air interface protocol; - A signaling procedure with a centralized network entity for distributing cell-specific cell identifiers; - A configuration determined by an operation and maintenance system; And - Information on cell identifiers used by the one or more cells configured for the second air interface protocol.

5. The method according to any one of claims 1 - 3, comprising: At the cell configured for the first air interface protocol, determining the air interface resource allocation based on information indicating a cell reference signal allocation of at least one cell configured for the second air interface protocol.

6. The method according to any one of claims 1 - 3, wherein the first air interface protocol is New Radio (NR), and the second air interface protocol is Long Term Evolution (LTE), and the cell identifier is a physical cell identifier for LTE.

7. A device for communication, comprising: Components for generating a cell reference signal at a cell configured for a first air interface protocol based on a cell identifier of a second air interface protocol; Components for determining an air interface resource allocation of the first air interface protocol at the cell configured for the first air interface protocol based on the cell identifier of the second air interface protocol; And A component for the cell configured for the first air interface protocol to transmit the generated cell reference signal according to the determined air interface resource allocation.

8. The apparatus according to claim 7, comprising: A component for determining the air interface resource allocation based on reserving resource elements for the generated cell reference signal; And Transmit the generated cell reference signal on the reserved resource elements.

9. The apparatus according to claim 8, comprising: A component for rate matching the user data destined for the user equipment of the cell configured for the first air interface protocol to resource elements adjacent to the resource elements reserved for the generated cell reference signal at the cell configured for the first air interface protocol.

10. The apparatus according to any one of claims 7 to 9, comprising: A component for determining the cell identifier of the cell configured for the second air interface protocol at the cell configured for the first air interface protocol based on at least one of the following: - A signaling procedure with one or more cells configured for the second air interface protocol; - A signaling procedure with a centralized network entity for distributing cell-specific cell identifiers; - A configuration determined by an operation and maintenance system; And - Information on cell identifiers used by the one or more cells configured for the second air interface protocol.

11. The apparatus according to any one of claims 7 to 9, comprising: A component for determining the air interface resource allocation at the cell configured for the first air interface protocol based on information indicating the cell reference signal allocation of at least one cell configured for the second air interface protocol.

12. The apparatus according to any one of claims 7 to 9, wherein the first air interface protocol is New Radio (NR), and the second air interface protocol is Long Term Evolution (LTE), and the cell identifier is a physical cell identifier for LTE.

13. A communication apparatus, according to comprising one or more processors and a memory storing instructions, which when executed by the one or more processors, cause the apparatus to: Generate a cell reference signal at a cell configured for a first air interface protocol based on a cell identifier of a second air interface protocol; Determine the air interface resource allocation of the first air interface protocol at the cell configured for the first air interface protocol based on the cell identifier of the second air interface protocol; And Transmit the generated cell reference signal by the cell configured for the first air interface protocol according to the determined air interface resource allocation.

14. The apparatus according to claim 13, being caused to perform any of the methods of claims 1 to 6.

15. A computer program product, the computer program product comprising instructions which, when executed by a processor, cause the processor to at least perform the following: Generate a cell reference signal at a cell configured for a first air interface protocol based on a cell identifier of a second air interface protocol; At the cell configured for the first air interface protocol, determine the air interface resource allocation of the first air interface protocol based on the cell identifier of the second air interface protocol; and Transmit the generated cell reference signal by the cell configured for the first air interface protocol according to the determined air interface resource allocation.

16. A non-transitory computer-readable medium, comprising program instructions for causing a device to at least perform the following: Generate a cell reference signal at a cell configured for a first air interface protocol based on a cell identifier of a second air interface protocol; At the cell configured for the first air interface protocol, determine the air interface resource allocation of the first air interface protocol based on the cell identifier of the second air interface protocol; and Transmit the generated cell reference signal by the cell configured for the first air interface protocol according to the determined air interface resource allocation.

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