WO2020233789A1

WO2020233789A1 - System design and related signaling for unpaired carrier flexible fdd

Info

Publication number: WO2020233789A1
Application number: PCT/EP2019/063045
Authority: WO
Inventors: Klaus Ingemann Pedersen; Guillermo POCOVI
Original assignee: Nokia Technologies Oy
Priority date: 2019-05-21
Filing date: 2019-05-21
Publication date: 2020-11-26

Abstract

An apparatus and a method are provided by which, at a user equipment, a frequency division duplexing configuration is received, and transmitting and/or receiving based on the frequency division duplexing configuration for unpaired frequency bands is performed, wherein the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

Description

SYSTEM DESIGN AND RELATED SIGNALING FOR UNPAIRED

CARRIER FLEXIBLE FDD

Field of the Invention

The present invention relates to an apparatus, a method and a computer program product by which a system and related signaling for unpaired flexible FDD can be achieved .

Related background Art

The following meanings for the abbreviations used in this specification apply:

AMF Access and Mobility Management Function

BW Bandwidth

BWP Bandwidth part

CLI Cross link interference

CORESET Control resource set

CSI Channel State Information

CSS Common search space

DCI Downlink Control Information

DL Downlink

FDD Frequency division duplexing

gNB NR node B

NR New Radio

NW Network

MIB Master Information Block

PDCCH Physical Downlink Control Channel

RAN Radio Access Network

RB Resource block

REG Resource element group RRM Radio Resource Management

RSRP Reference signal received power

RSRQ Received signal received quality

RSSI Received Signal Strength Indicator

SIB System information block

SS Search space

TCI Transmission configuration indication

TDD Time division duplexing

TSN Time sensitive network

TTI Time Transmission Interval

U E User Equipment

U L Uplink

U PF User Plane Function

U RLLC Ultra-reliable low latency communications

Example embodiments, although not limited to this, relate to the evolution of 3GPP NR Rel- 15 and 16 which supports two duplexing modes: FDD for paired bands and TDD for unpaired bands. URLLC is one of the new use cases introduced with NR. Evaluations show NR Rel- 15 fulfils the U RLLC ( 1 ms latency with 99.999% reliability) requirement for both FDD and TDD. Similarly, also NR Rel- 16 is set to fulfil the eURLLC ( 1 ms latency with 99.9999% reliability). The (e)U RLLC requirements are obviously easier to fulfil for FDD deployments due to the constant availability of bi-directional transmission options, while they are much more problematic to support for unpaired TDD deployments. In fact, only having either uplink or downlink transmission per cell for traditional TDD cases, severely limits the possibility to simultaneously support multiple (e)U RLLC users that have traffic arrival at different time-instances. Similarly, to support the strict TSN requirements for deterministic traffic is extremely challenging for NR TDD, or in fact impossible as the offered traffic per cell is much larger and the requirements of latency and reliability may be stricter (see 3GPP TS 22.104). Summary of the Invention

Example embodiments of the present invention address this situation and aim to provide measures for allowing simultaneous downlink and uplink transmissions within an unpaired wideband NR carrier.

According to a first aspect, an apparatus is provided which comprises at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform : receiving a frequency division duplexing configuration, and transmitting and/or receiving based on the frequency division duplexing configuration for unpaired frequency bands, wherein the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

According to a second aspect, a method is provided which comprises:

receiving, at a user equipment, a frequency division duplexing configuration, and

transmitting and/or receiving based on the frequency division duplexing configuration for unpaired frequency bands, wherein

the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

The first and second aspects may be modified as follows:

On frequency resources in the static downlink and/or uplink frequency regions, measurements may be performed and/or control related messages may be received and/or transmitted. The apparatus or user equipment may be capable of either receiving or transmitting at a certain time instant in an unpaired band, or the apparatus is capable of receiving and transmitting at the same time instant in an unpaired band.

According to a third aspect, an apparatus is provided which comprises at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform : preparing a frequency division duplexing configuration for unpaired frequency bands, and transmitting the frequency division duplexing configuration to a user equipment, wherein the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

According to a fourth aspect, a method is provided which comprises:

preparing, at a network control element, a frequency division duplexing configuration for unpaired frequency bands, and

transmitting the frequency division duplexing configuration to a user equipment, wherein

The third and fourth aspects may be modified as follows:

Transmitting and/or receiving to/from the user equipment may be performed based on the configuration.

Control related messages may be received from and/or transmitted to the user equipment on frequency resources in the static downlink and/or uplink frequency regions. The dynamic downlink and uplink frequency resources may be adjusted dynamically.

The frequency division duplexing configuration may be transmitted to another network control element.

Moreover, cross link interference may be detected, and the frequency division duplexing configuration may be adjusted based on the detected cross link interference.

Furthermore, it may be negotiated with an other network control element causing the cross link interference for adjusting the frequency division duplexing configuration.

Negotiating with the other network control element may be performed by sending a message including a suggestion for an amended frequency division duplexing configuration to be applied by the other network control element.

A suggestion for a frequency division duplexing configuration may be received from another network control element, and the frequency division duplexing configuration used for transmitting and/or receiving to/from the user equipment may be adapted based on the suggestion.

The above first to fourth aspects may be modified as follows:

Each of the static and dynamic downlink and uplink regions may be contiguous regions having contiguous frequency resources.

The static downlink regions may comprise frequency resources blocks having the lowest frequencies in the carrier and the static uplink regions comprises frequency resources having the highest frequencies in the carrier, or the static downlink regions comprise frequency resources blocks having the highest frequencies in the carrier and the static uplink regions comprises frequency resources having the lowest frequencies in the carrier.

A guard band may be provided between the dynamic downlink and uplink frequency regions, the guard band consisting of frequency resources on which transmitting and receiving is not carried out.

The frequency division duplexing configuration may be a flexible frequency division duplexing configuration.

According to an fifth aspect of the present invention a computer program product is provided which comprises code means for performing a method according to any one of the second and fourth aspects and/or their modifications when run on a processing means or module. The computer program product may be embodied on a computer-readable medium, and/or the computer program product may be directly loadable into the internal memory of the computer and/or transmittable via a network by means of at least one of upload, download and push procedures.

According to a sixth aspect an apparatus is provided which comprises means for receiving a frequency division duplexing configuration, and means for transmitting and/or receiving based on the frequency division duplexing configuration for unpaired frequency bands, wherein the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

According to a seventh aspect an apparatus is provided which comprises means for preparing a frequency division duplexing configuration for unpaired frequency bands, and means for transmitting the frequency division duplexing configuration to a user equipment, wherein the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

The sixth and seventh aspects may be modified similar as the first and third aspects.

Brief Description of the Drawings

These and other objects, features, details and advantages will become more fully apparent from the following detailed description of example embodiments of the present invention which is to be taken in conjunction with the appended drawings, in which :

Fig. 1A shows a UE 1 according to an example embodiment,

Fig. IB shows a procedure carried out by the UE 1 according to an example embodiment,

Fig. 2A shows a gNB 2 according to an example embodiment,

Fig. 2B shows a procedure carried out by the gNB 2 according to an example embodiment,

Fig. 3 shows a basic illustration of unpaired carrier with flexible FDD configuration,

Fig. 4 illustrates a high-level sketch of flexible FDD carrier configuration for unpaired band according to an example embodiment, and

Fig. 5A shows a simplified RAN architecture for NR, and Fig. 5B shows a split architecture of a gNB in NR. Detailed Description of example embodiments

In the following, description will be made to example embodiments of the present invention. It is to be understood, however, that the description is given by way of example only, and that the described example embodiments are by no means to be understood as limiting the present invention thereto.

Before describing example embodiments in detail, the problem underlying the present application is described in some more detail.

In order address the problems of fulfilling (e)URLLC and TSN requirements for unpaired bands as described in the introductory part above, it is proposed to introduce a new flexible duplexing mode for coming NR releases (such as Rel-17, and beyond). This duplexing mode is referred to as flexible FDD for unpaired bands. The idea is to allow simultaneous downlink and uplink transmission on different PRBs within an unpaired wideband NR carrier. A high-level sketch of the principle is illustrated in Fig. 3, where the downlink and uplink transmission regions are separated by a guard band (corresponding to blanked frequency-domain resources; PRBs/ subcarriers). This would e.g. be relevant for future NR deployments in the 3.5 GHz band for industrial automation, where 40-200MHz unpaired carriers could be made available. However, the invention is not limited to such bands, so it is generally applicable to any bands.

Example embodiments address the problems of how to configure and dynamically reconfigure unpaired flexible FDD carriers from a system perspective. This includes signaling solutions to allow efficient inter-cell coordination, NW to UE signaling to have aligned operation for data and control transmission, as well as for UE measurements such as RRM (RSRP/RSSI/RSRQ) and PHY (e.g. CSI). All three NR RRC states are considered. In the following, relevant definitions as currently defined for NR are summarized. In particular, as will be visible later, the NR Bandwidth Part (BWP) concept is useful for creating support for flexible FDD in NR. In short, the BWP types defined for NR Rel-15 are:

Initial-active DL BWP #0: The initial-active DL BWP #0 is defined by span of CORESET#0 configured by MIB (alternatively configured by dedicated RRC) for scheduling of SIBs. It determines DCI format l_0/0_0 (DL/UL fallback) size in CSS. Supported sizes thereof are only 24, 48, 96 RB.

Initial-active UL BWP #0: The initial-active UL BWP #0 is configured by SIB1 for random access procedure. It determines RA field size in DCI format 0_0 (UL fail-back).

Default DL BWP or DL/UL BWP pair: The default DL BWP or DL/UL BWP pair is configured by dedicated RRC as BWP to be switched-to when an inactivity- timer expires. If it is not configured, the default DL BWP is the initial-active DL BWP.

First-active DL and UL BWP: On Peel I, the first-active DL and UL BWP is the first active BWP after initial access. On PScell, this is the first active BWP after random access. On Scell, this is the first active BWP after activation by MAC- CE.

Dedicated DL and UL BWP: This is a regular BWP configured in a dedicated manner.

For unpaired spectrum (TDD), UE can be configured with initial DL/UL BWP and up to 4 UL-DL BWP-pairs in a serving cell, center frequency for UL and DL is the same. BWP with same BWP-ID form a pair. Only one DL and UL BWP or BWP-pair is active for the UE at any given time in a serving cell in R15. In contrast thereto, according to some example embodiments as described later, the restriction that the center frequency for UL and DL is the same is removed for flexible FDD.

In the following, some configuration details of BWPs are briefly described.

In a serving cell with PUCCH, every BWP has to have PUCCH resources configured. This is necessary, since otherwise a change to a BWP with no PUCCH resource would lead to no PUCCH resource to transmit on.

Each BWP has CORESET(s) except in case of cross-carrier scheduling and in case search-space-set#0 is to be tagged. This is necessary because otherwise after switch to a BWP with no CORESET, UE would not be able to receive PDCCH.

The UE is not expected to be configured without CSS on the Pcell and PScell.

PRACH can be configured on each UL BWP of PCell(PSCell). This leads to an autonomous UL BWP switch if PRACH not configured on a BWP.

The NR architecture is specified in 3GPP technical specification 38.401, "Technical Specification Group Radio Access Network; NG-RAN; Architecture description", Version 15.1.0, Release 15, March 2018.

Among others, this includes an Xn-C interface between the gNBs to coordinate by means the XnAP procedures as defined in 3GPP TS 38.423, as well as an NG interface towards the 5G core network (5GC). The 5G NR architecture also allows C-RAN implementations with one or multiple centralized units (CU), each serving a large number of distributed units (DU). Such CU-DU options are made possible by the introduction of the two new interfaces named El (between the control and user plane in the CU) and FI (between the CU and DU). The El interface is specified in TS 38.460 (Stage 2); TS 38.463 (Stage-3), and the FI interface is specified in TS 38.470 (Stage 2); TS 38.473 (Stage 3). As will be described in the following in more detail, according to some example embodiments, new information elements for both the Xn and FI interfaces to enable efficient system-level support for flexible FDD on unpaired carriers.

In the following, a general overview of some example embodiments is described by referring to Figs. 1A, IB, 2A and 2b.

In particular, Fig. 1A shows an UE 1 as an example for a first apparatus according to the present example embodiment. However, the invention is not limited to an UE, but can be any kind of terminal device. Fig. IB illustrates a process carried out by the UE 1.

The UE 1 comprises at least one processor 11, at least one memory 12 including computer program code. The at least one processor 11, with the at least one memory 12 and the computer program code, is configured to cause the apparatus to perform : receiving a frequency division duplexing configuration for unpaired frequency bands (Sll in Fig. IB), and transmitting and/or receiving based on the frequency division duplexing configuration (S12 in Fig. IB), wherein the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

Fig. 2A shows an gNB 2 as an example for a second apparatus according to the present example embodiment. However, the invention is not limited to an gNB, but can be any kind of network control device. Fig. IB illustrates a process carried out by the gNB 2.

The gNB 2 comprises at least one processor 21 and at least one memory 22 including computer program code. The at least one processor 21, with the at least one memory 22 and the computer program code, is configured to cause the apparatus to perform: preparing a frequency division duplexing configuration for unpaired frequency bands (step S21 in Fig. 2B), and transmitting the frequency division duplexing configuration to a user equipment (e.g., to UE 1 shown in Fig. 1A) (step S22 in Fig. 2B), wherein the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated.

The UE 1 may further comprise an I/O unit 13, which is capable of transmitting to the gNB 2 via a radio network. Likewise, the gNB 2 may further comprise an I/O unit 23, which is capable of transmitting to the UE 1 via the radio network, and may also be capable to provide a connection to other network control elements such as other gNBs.

Thus, according to some example embodiments, a flexible FDD solution for unpaired bands is achieved, which provides both a static frequency region and a dynamic frequency region. That is, in a carrier, the frequency resources (e.g., subcarriers, RBs (resource blocks) and the like) are allocated to static downlink and uplink frequency regions or to dynamic downlink and uplink frequency regions.

In this way, it is possible to efficiently configure and dynamically reconfigure unpaired flexible FDD carriers.

Generally, the time interval for changing the static downlink and uplink regions described above is longer than the time interval for changing the dynamic downlink and uplink regions. As will be explained later in more detail, according to some example embodiments, the time interval for changing the dynamic downlink and uplink regions may be shorter than a minute, whereas the time interval for changing the static downlink and uplink regions may longer than an hour. Thus, according to one example embodiment, the time interval for changing the static downlink and uplink regions may be at least 60 times of the time interval for changing the dynamic downlink and uplink regions.

Each of the static and dynamic downlink and uplink regions may be contiguous regions having contiguous frequency resources, as shown in Fig. 4 described later, for example. Moreover, a guard band may be provided between the dynamic downlink and uplink frequency regions, the guard band consisting of frequency resources on which transmitting and receiving is not carried out.

Furthermore, the UE may perform measurements (such as RRM measurements etc.) and/or receive and/or transmit control related messages (such as a paging message for call setup, an MIB, RRC) on frequency resources in the static downlink and/or uplink frequency regions. For example, the UE, when idle or inactive, may use the static uplink frequency region for initial random access.

In the following, some example embodiments are described in more detail.

According to example embodiments, the following concept and set of procedures is proposed :

According to example embodiments, a flexible FDD duplexing solution for unpaired bands ala illustrated in Fig. 4, where each carrier (cells) has static downlink and uplink frequency regions (uplink transmission frequency domains), dynamic downlink and uplink frequency regions (domains), and a guard band between the downlink and uplink frequency regions (resource regions). The example shown in Fig. 4 illustrates flexible FDD carrier configurations for two different cells Cell # 1 and Cell#2, wherein the guard band between the dynamic downlink (DL) frequency region and the dynamic uplink (UL) frequency region is indicated by a thick black line.

The static downlink and uplink frequency regions are assumed to be "static". That is, not changing over time, or at most be configured on time-scales of hours, days, weeks, or months. The static downlink and uplink frequency regions are coordinated between neighboring cells, so there is marginal cross link-interference (CLI) for those resources. Coordination may happen via the Xn or FI interfaces, or from OAM.

The static downlink frequency region is used by UEs to perform RRM (e.g. mobility) measurements and is also the resources where a UE may receive a paging message (for call setup). MIB is sent on the static downlink resources, i.e., in the static downlink frequency region.

The static uplink frequency region is used by RRC IDLE and RRC INACTIVE UEs for initial Random Access.

The dynamic downlink and uplink frequency regions (resource domains) can be dynamically adjusted. According to a certain example embodiment, the dynamic adjustments may be as fast as on radio slot-level, or on a slower time-scales of tens of milliseconds, or even slower (say e.g. on scales of minutes).

Dynamic inter-cell signaling of flexible FDD carrier configuration is conducted over Xn and FI interfaces.

Fig. 5A shows a simplified RAN architecture for NR, in which Xn interfaces are shown. In particular, Fig. 5A shows an example in which three gNBs, gNB A, gNB B and gNB C, are provided, which are interconnected. Between the gNBs, the Xn interface is defined. Moreover, the gNBs are connected to an AMF (Access and Mobility Management Function) / UPF (User Plane Function) via an NG interface.

Fig. 5B shows the split architecture of a gNB in NR. In particular, the gNB may comprise a CU (central unit) and one or more DUs (distributed units). The FI interface is defined between CU and DU. Procedures for detecting potential harmful CLI, and conflict resolutions to align flexible FDD carrier configurations between neighboring cells by means of Xn and FI procedures.

New network (NW) to UE signaling procedures to inform UEs of flexible FDD carrier config, as well as to facilitate synchronized carrier reconfigurations.

Specific procedures for supporting new terminal (UE) types with full-duplex and half-duplex flexible FDD capable UEs for unpaired bands.

In the following, some more detailed implementation examples are described. Moreover, also the differences with respect to the current 3GPP NR specifications are highlighted.

According to a certain example embodiment, a possible realization is the following :

1. The static downlink and uplink frequency regions (resource regions) are configured as the Initial-active DL BWP #0 and the Initial-active UL BWP #0 for the flexible FDD unpaired carriers. Those two initial-active BWPs will need to have different center frequencies as they are non-overlapping. It is noted that this is a modification as compared to Rel-15 specs.

2. RRC IDLE, RRC INACTIVE, and RRC CONNECTED mode shall perform RRM (RSRP and RSRQ) measurements on the Initial-active DL BWP #0. RRC IDLE and RRC INACTIVE UE perform Random Access only on the Initial UL BWP.

3. The MIB shall be extended with one additional bit indicating the carrier is of type "flexible FDD for unpaired band". It is noted that this is new as compared to Rel-15 specs. 4. The total downlink frequency (resource) region (static and dynamic part, i.e., the static and dynamic downlink frequency regions) is configured as the default downlink BWP. Similarly, the total uplink resource region (static and dynamic part, i.e., the static and dynamic uplink frequency regions) is configured as the default uplink BWP. Notice that although this is for an unpaired carrier, the center frequency for those default BWP will be different. It is noted that this is a modification as compared to Rel-15 specs. Signaling of default BWPs is by means of RRC signaling towards the UEs, or could be made cell-specific or UE group common signaling.

5. For the distributed network architecture, the gNB shall report the flexible FDD carrier configuration to its neighboring gNB(s) as over the Xn interface. The flexible FDD carrier configuration is expressed as the frequency range of the downlink and uplink static and dynamic resource parts, as well as the guard band. Those may be expressed in units of Hz, PRBs, subcarriers, or other means. Signaling of flexible FDD carrier configuration could be included in the Xn Setup and NG-RAN Node Configuration Update procedures (3GPP TS38.423). It is noted that this is new as compared to Rel-15 specs.

6. A gNB that experience too high CLI from a neighboring gNB (as a result of two gNBs using different flexible FDD carrier configurations) should be able to send a "CLI Alert Message" to its neighboring gNB with suggestion for that gNB to adjust it flexible FDD carrier configuration to have reduced CLI regions (i.e. frequency resources where the two gNBs have opposite link directions). The gNB receiving the "CLI Alert Message" respond by sending back a potentially new flexible FDD carrier configuration (expressing how it may have adjusted its carrier configuration to reduce the CLI). This is also new as compared to Rel-15 specs.

7. When using the CU / DU split architecture, the CU would take the role as the master and decide the flexible FDD carrier configuration for all DU (cells) under its command. A new message shall therefore be defined for the FI interface, allowing the CU to dictate which flexible FDD carrier configurations the cells on the DUs shall use. It is noted that this is also new as compared to Rel-15 specs.

8. Based on e.g. the offered traffic conditions, a gNB (or CU) can decide to modify the resource split downlink and uplink frequency-domain resources. This is carried out by the gNB sending a new synchronized reconfiguration update message to all its RRC CONNECTED mode UEs to reconfigure the Default Downlink and Uplink BWPs. This may be sent as a cell-specific broadcast message. It is noted that this is new as compared to Rel-15 specs.

In an alternative example embodiment, the above procedure 4 may be modified such that the Default Downlink and Uplink BWPs for some or all UEs are configured to be overlapping or partly overlapping, and instead letting the MAC-level scheduler dynamically per TTI decide how users are scheduled in the uplink and downlink directions. This essentially allows the gNB to alter the downlink / uplink resource split on a per TTI (or slot) basis.

In the following, terminal aspects and categories according to some example embodiments are described.

For example, according to a certain example embodiment, the flexible FDD carrier operation as illustrated in Fig. 4 may only be supported at the gNB, while all, or some UEs, may support only half-duplexing operation, where they can either receive or transmit at each time-instant. For such cases, the gNB must respect half-duplex UE transmission/reception constraints, and new TDD half-duplex.

Thus, in case of full-duplex flexible FDD duplex UEs (for unpaired bands), these UEs are able to receive and transmit at same time-instances at different frequency resources. Scheduling (uplink and downlink) of such UEs will happen via scheduling grants (send on PDCCH in the downlink region). Full- duplex flexible FDD duplex UEs is a new UE category, and signaling of related category information shall be signaled to the gNB. In the other hand, half-duplex flexible FDD duplex UEs (for unpaired bands) are either receiving or transmitting at a certain time-instant. Uplink and Downlink transmission happens at different frequency resources as per the serving cells flexible FDD carrier configuration. Scheduling (uplink and downlink) of such UEs will happen via scheduling grants (send on PDCCH in the downlink region). Half-duplex flexible FDD duplex UEs is a new UE category, and signaling of related category information shall be signaled to the gNB. Supporting such a UE category will require new signaling and DCI format(s); incl. enhancements for signaling of e.g. TDD-UL-DL- ConfigurationCommon and TDD-UL-DL-ConfigDedicated (as defined in Section 11.1 in 3GPP TS 38.213). More details are described in the following.

In the following, slot formats and related gNB-2-UE signaling are described.

The 5G NR Rel-15 frame structure is designed to be highly flexible. A radio frame is 10 ms, and consists of a series of 1 ms subframes. Each frame is divided into two equally-sized half-frames of five subframes each with half frame 0 consisting of subframes 0 - 4 and half-frame 1 consisting of subframes 5 - 9. The number of slots per subframe / radio frame depends on the subcarrier spacing. For 15 kHz there is one slot per subframe, for 30 kHz there are two slots per subframe, for 60 kHz there are four slots per subframe, and so forth. A slot consists of 14 OFDM symbols for cases with normal cyclic prefix, while it equals only 12 OFDM symbols for the case with extended cyclic prefix and subcarrier spacing of 60 kHz. A larger number of possible slot formats are defined (3GPP TS 38.213), where "D" indicates downlink symbol, "U" indicates uplink symbol, and "F" is flexible. As an example, slot format 0 and 1 corresponds to downlink-only and uplink-only slots, respectively. Slot format 36 contain first three downlink transmission symbols, followed by "F" (which could be set to mute for guard period), and ten uplink transmissions. For unpaired carriers (using TDD for NR Rel-15 and Rell6), there is one, and only one, slot format used per time-instant per cell. This is not enough for the flexible FDD carrier concept according to example embodiments. As per 3GPP TS 38.213, the gNB may inform the UEs of the used slot format. The following example text from 38.213, clause 11.1 :

If a UE is provided higher layer parameter TDD-UL-DL-ConfigurationCommon, the UE shall set the slot format per slot over a number of slots as indicated by higher layer parameter UL-DL-configuration-common. If the UE is additionally provided higher layer parameter TDD-UL-DL-ConfigDedicated for the slot format per slot over the number of slots, the parameter TDD-UL-DL- ConfigDedicated overrides only flexible symbols per slot over the number of slots as provided by TDD-UL-DL-ConfigurationCommon.

Hence, according to some example embodiments, for the flexible FDD carrier concept, new options for signaling of "TDD-UL-DL-ConfigurationCommon" and " TDD-UL-DL-ConfigDedicated " are defined. Those would be redefined to cover cases, where the signaling of UL-DL configurations (common and dedicated) include simultaneous use of two different slot formats per time instant at different frequency ranges as per the illustrations in Fig. 3 and Fig. 4. Resources not included in those UL-DL configurations (common and dedicated) are implicitly assumed to be guard band resources. In yet another embodiment, a more agile signaling of those redefined UL-DL configurations (common and dedicated) could be used to facilitate fast adjust of Downlink and Uplink resource regions.

In the following, some scheduling strategies at the gNB according to an example embodiment are described. In particular, the flexible FDD carrier concept opens the doors for novel QoS- and CLI-aware scheduling approaches at the gNB. For cases where the MAC can dynamically (per TTI) decide what resources are used for uplink and downlink transmissions, a potential implementation of the radio scheduler could be as follows: Each gNB prioritize scheduling on the static downlink and uplink resource regions, as they are free from cross-link interference. If there are insufficient UL and/or DL resources on the static region on a certain scheduling instant, resources from the dynamic regions can be used (with a risk of degraded signal quality due to CLI). Using the sketch in Fig. 4 as a reference, gNBs could also agree to prioritize scheduling of dynamic resources in a top-to-bottom fashion for DL, or bottom-to-top fashion for UL, or potentially just following UE's CSI measurements. Besides, the QoS of each transmission may also be accounted when conducting the scheduling decisions. For instance, critical URLLC or TSN traffic may have priority on the static part as these are free from CLI.

The above-described example embodiments are only examples and may be modified.

For example, according to some example embodiments, the gNB serving the UE prepares the frequency division duplex configuration. However, the invention is not limited by this, and the frequency division duplex configuration may be prepared by another suitable network element.

Names of network elements, protocols, and methods are based on current standards. In other versions or other technologies, the names of these network elements and/or protocols and/or methods may be different, as long as they provide a corresponding functionality.

In general, the example embodiments may be implemented by computer software stored in the memory (memory resources, memory circuitry) 12, 22 and executable by the processor (processing resources, processing circuitry) 11, 21 or by hardware, or by a combination of software and/or firmware and hardware.

As used in this application, the term "circuitry" refers to all of the following :

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) to combinations of circuits and software (and/or firmware), such as (as applicable) : (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of "circuitry" applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

The terms "connected," "coupled," or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are "connected" or "coupled" together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be "connected" or "coupled" together by the use of one or more wires, cables and printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as non-limiting examples.

The memory (memory resources, memory circuitry) 12, 22 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, and non- transitory computer-readable media. The processor (processing resources, processing circuitry) 11, 21 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi core processor architecture, as non-limiting examples.

It is to be understood that the above description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications and applications may occur to those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.

Claims

1. An apparatus comprising

at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform :

receiving a frequency division duplexing configuration, and

the frequency division duplexing configuration defines static downlink and uplink frequency regions and dynamic downlink and uplink frequency regions to which frequency resources of a carrier are allocated .

2. The apparatus according to claim 1, wherein

each of the static and dynamic downlink and uplink regions are contiguous regions having contiguous frequency resources.

3. The apparatus according to claim 1 or 2, wherein

the static downlink regions comprise frequency resources blocks having the lowest frequencies in the carrier and the static uplink regions comprises frequency resources having the highest frequencies in the carrier, or

the static downlink regions comprise frequency resources blocks having the highest frequencies in the carrier and the static uplink regions comprises frequency resources having the lowest frequencies in the carrier.

4. The apparatus according to any one of the claims 1 to 3, wherein a guard band is provided between the dynamic downlink and uplink frequency regions, the guard band consisting of frequency resources on which transmitting and receiving is not carried out.

5. The apparatus according to any one of the claims 1 to 4, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

performing measurements and/or receiving and/or transmitting control related messages on frequency resources in the static downlink and/or uplink frequency regions.

6. The apparatus according to any one of the claims 1 to 5, wherein the apparatus is capable of either receiving or transmitting at a certain time instant in an unpaired band, or the apparatus is capable of receiving and transmitting at the same time instant in an unpaired band.

7. The apparatus according to any one of the claims 1 to 6, wherein the frequency division duplexing configuration is a flexible frequency division duplexing configuration.

8. An apparatus comprising

preparing a frequency division duplexing configuration for unpaired frequency bands, and

9. The apparatus according to claim 8, wherein

10. The apparatus according to claim 8 or 9, wherein

11. The apparatus according to any one of the claims 8 to 10, wherein a guard band is provided between the dynamic downlink and uplink frequency regions, the guard band consisting of frequency resources on which transmitting and receiving is not carried out.

12. The apparatus according to any one of the claims 8 to 11, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

transmitting and/or receiving to/from the user equipment based on the configuration.

13. The apparatus according to any one of the claims 8 to 12, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

receiving and/or transmitting control related messages to/from the user equipment on frequency resources in the static downlink and/or uplink frequency regions.

14. The apparatus according to any one of the claims 8 to 13, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

dynamically adjusting the dynamic downlink and uplink frequency resources.

15. The apparatus according to any one of the claims 8 to 14, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

transmitting the frequency division duplexing configuration to another network control element.

16. The apparatus according to any one of the claims 8 to 15, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

detecting cross link interference, and

adjusting the frequency division duplexing configuration based on the detected cross link interference.

17. The apparatus according to claim 16, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

negotiating with an other network control element causing the cross link interference for adjusting the frequency division duplexing configuration.

18. The apparatus according to claim 17, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

negotiating with the other network control element by sending a message including a suggestion for an amended frequency division duplexing configuration to be applied by the other network control element.

19. The apparatus according to any one of the claims 8 to 18, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform :

receiving a suggestion for a frequency division duplexing configuration from another network control element, and adapting the frequency division duplexing configuration used for transmitting and/or receiving to/from the user equipment based on the suggestion.

20. The apparatus according to any one of the claims 8 to 19, wherein the frequency division duplexing configuration is a frequency division duplexing configuration.

21. A method comprising :

22. The method according to claim 21, wherein

23. The method according to claim 21 or 22, wherein

24. The method according to any one of the claims 21 to 23, wherein a guard band is provided between the dynamic downlink and uplink frequency regions, the guard band consisting of frequency resources on which transmitting and receiving is not carried out.

25. The method according to any one of the claims 21 to 24, further comprising :

26. The method according to any one of the claims 21 to 25, further comprising

receiving or transmitting at a certain time instant in an unpaired band receiving and transmitting at the same time instant in an unpaired band.

27. The method according to any one of the claims 21 to 26, wherein the frequency division duplexing configuration is a flexible frequency division duplexing configuration.

28. A method comprising :

29. The method according to claim 28, wherein

each of the static and dynamic downlink and uplink regions are contiguous regions having contiguous frequency resources

30. The method according to claim 28 or 29, wherein the static downlink regions comprise frequency resources blocks having the lowest frequencies in the carrier and the static uplink regions comprises frequency resources having the highest frequencies in the carrier, or

31. The method according to any one of the claims 28 to 30, wherein a guard band is provided between the dynamic downlink and uplink frequency regions, the guard band consisting of frequency resources on which transmitting and receiving is not carried out.

32. The method according to any one of the claims 28 to 31, further comprising :

33. The method according to any one of the claims 28 to 32, further comprising :

34. The method according to any one of the claims 28 to 33, further comprising :

dynamically adjusting the dynamic downlink and uplink frequency resources.

35. The method according to any one of the claims 28 to 34, further comprising :

36. The method according to any one of the claims 28 to 35, further comprising :

detecting cross link interference, and

37. The method according to claim 36, further comprising :

38. The method according to claim 37, further comprising :

39. The method according to any one of the claims 28 to 38, further comprising :

receiving a suggestion for a frequency division duplexing configuration from another network control element, and

adapting the frequency division duplexing configuration used for transmitting and/or receiving to/from the user equipment based on the suggestion.

40. The method according to any one of the claims 28 to 39, wherein the frequency division duplexing configuration is a frequency division duplexing configuration.

41. A computer program product comprising code means for performing a method according to any one of the claims 21 to 40 when run on a processing means or module.

42. The computer program product according to claim 41, wherein the computer program product is embodied on a computer-readable medium, and/or the computer program product is directly loadable into the internal memory of the computer and/or transmittable via a network by means of at least one of upload, download and push procedures.