How to operate the secondary station

Abstract

A method for operating a wireless terminal to communicate in a cellular network, the cellular network having at least a first cell station serving a first cell and at least one relay station served by a second cell station serving a second cell, the method comprising: receiving, by the wireless terminal, a downlink signal sent by the first cell station, the downlink signal carrying downlink control information, the downlink control information including at least an indication of assigned uplink resources to be used by the wireless terminal to transmit a signal to the relay station; generating, by the wireless terminal, uplink information; and transmitting, by the wireless terminal, a signal carrying the uplink information to the relay station on the assigned uplink resources, the uplink information to be forwarded to the second cell station.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication, and more particularly, to relay architectures in the context of cellular networks such as UMTS Long Term Evolution (LTE), LTE-Advanced (both included in 4G), New Radio (NR) (5G), or other cellular or mobile communication networks.

Background Art

[0002] In a conventional cellular network, a primary station serves a plurality of secondary stations within the cell served by this primary station. Wireless communication from the primary station to each secondary station is performed on a downlink channel. Conversely, wireless communication from each secondary station to the primary station is performed on an uplink channel. Wireless communication can include data traffic (sometimes called user data) and control information (sometimes called signaling). This control information typically has information for assisting the primary station and / or the secondary stations in exchanging data traffic (e.g., resource allocation / request, physical transmission parameters, information about the state of each station). Data traffic typically includes a useful payload exchanged for the use of end-user applications. Data traffic is typically composed of IP (Internet Protocol) packets carried within the data plane.

[0003] In the context of cellular networks, such as those standardized by 3GPP (registered trademark), the primary station is called a base station, i.e., a gNodeB (or gNB) in 5G (NR), an eNodeB (or eNB) in 4G (LTE), or a cell station. The eNB / gNB is part of the Radio Access Network (RAN) and interfaces to the functions of the Core Network (CN). In the same context, the secondary station corresponds to the mobile station, i.e., the user equipment (or UE) in 4G / 5G, and is a wireless client device, or has a specific role played by such a device. The term "node" is further used to represent the UE or gNB / eNB. "NF" represents the network function of the CN. The direct link between the primary and secondary stations is called the Uu interface in 4G or 5G networks.

[0004] Secondary stations can be equipped with different types of wireless terminals, such as mobile phones, vehicles (with V2V vehicle-to-vehicle or more common V2X vehicle-to-vehicle / vehicle-to-infrastructure communication capabilities), IoT devices (including low-power medical sensors for health monitoring, and medical (emergency) diagnostic and treatment devices for hospitals or first responders), virtual reality (VR) headsets, or general wireless wearables. These wireless terminals differ very significantly in terms of their operation or characteristics, for example, in terms of low-power operation, required bandwidth / data rate, maximum allowable latency, achievable transmit power, achievable duty cycles during transmission and / or reception, or required mobility. The bandwidth available to a device for uplink (UL) and downlink (DL) data may change dynamically under the control of the base station based on data needs and the channel conditions at that time. A scheduler exists within the base station to schedule UL / DL transmissions from the device.

[0005] In 3GPP®, the role of a relay node has been introduced, as shown in Figure 1A. This relay node 120 is a wireless communications station 120 that has the function of relaying communication between a base station 100 (e.g., a gNB) and a UE 110. This relay function helps, for example, extend the coverage of cell 10 to a mobile station 110 that is out of coverage (OoC). This relay node 120 can be a mobile station or a different type of device. In the 4G specification, proximity services (ProSe) functionality is defined in particular in TS23.303 and TS24.334 to enable connectivity for cellular user equipment (UE) 110 that is temporarily not within the coverage of a cellular network base station (eNB) 100 serving cell 10. This particular function is called ProSe UE-to-network relay, or simply relay UE. The relay UE120 relays application and network traffic in two directions between the OoC UE110 and the eNB100. Local communication between the relay UE120 and the OoC UE110 is referred to in TS23.303 and TS24.334 as device-to-device (D2D) communication or sidelink (also known as PC5) communication. As soon as the relay relationship is established, the OoC-UE110 is IP connected via the relay UE120 and functions in the role of a “remote UE” 110. This situation means that the remote UE has indirect network connectivity (as defined in TS22.261) to selected core network functions, as opposed to direct network connectivity to all core network functions, which is the usual case.

[0006] However, direct communication with a distant gNB requires high energy consumption from a (wireless, typically battery-powered) wearable UE or IoT UE, while sidelink operations further involve energy-intensive operations such as sensing a control area to check whether a message is addressed to a remote UE. This leads to high energy consumption from a (wireless, typically battery-powered) wearable UE or IoT UE when communicating as a remote UE via such a relay UE for sensing. Note that in this application, the term “energy consumption” is used to refer to what may be indicated by the term “power consumption.” “Power consumption” is a physical misnomer, as power cannot be consumed. Power is the rate at which energy is “consumed,” or more precisely, the rate at which one type of energy (e.g., electrochemical energy available through battery charging) is converted to another type of energy. Similarly, “power-saving mode” is actually a mode in which the power level of a device is set to a lower value than during normal operation, thereby saving energy, not power, in this mode (more precisely, not being converted quickly).

[0007] Furthermore, in addition to high energy consumption, the bandwidth available downstream to remote UEs indirectly connected (via the relay UE) is potentially limited, meaning that the relay UE may have insufficient downstream data capacity. For example, one reason for this bottleneck is that the resources allocated for sidelink (SL) communication required by the relay UE to send data to remote UEs are a very limited subset of the entire set of available cellular resources. The relay UE may need to serve multiple remote UEs simultaneously, and therefore, the relay UE's limited resources (spectrum, processing time, buffer memory, etc.) may need to be divided across multiple devices. Moreover, other remote UEs have a higher priority to be served by the relay UE. Another problem is the possibility of packet collisions due to overlapping resource allocation (in mode 2, as defined, for example, in TS38.300 and / or TR38.885 Rel.16 and later) when remote UEs are out of coverage and therefore no resources are scheduled for the remote UE to transmit. [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] One objective of the present invention is to alleviate the above-mentioned problems.

[0009] Another objective of the present invention is to propose a method for communicating over a network that enables reduced energy consumption for remote UEs.

[0010] Another objective of the present invention is to propose a method for a secondary station for network communication that improves latency while keeping energy consumption low.

[0011] Another object of the present invention is to propose a secondary station that can operate flexibly according to an optimal network topology in order to optimize energy consumption. [Means for solving the problem]

[0012] Accordingly, according to a first aspect of the present invention, a wireless terminal for communication in a cellular network is proposed as described in claim 1, wherein the cellular network comprises at least one first cell station serving a first cell and at least one relay station served by a second cell station serving a second cell. Wireless devices, A controller operating in TX-limited mode, which is adapted to generate uplink information, In TX-restricted operation mode, a receiver configured by a controller to receive a first downlink signal directly transmitted by a first cell station, the first downlink signal carrying each of the first downlink control information, wherein at least one of the first downlink control information includes at least an instruction for a first configuration parameter to be used by a wireless terminal to transmit the signal directly to a relay station, and at least one of the first downlink control information includes at least a second configuration parameter to be used by a wireless terminal to receive further downlink signals directly from the first cell station, In TX-restricted operation mode, a transmitter configured by the controller to transmit a second signal carrying uplink information to be forwarded to a second cell station to a relay station using first configuration parameters, and Equipped with, The receiver is further adapted to directly receive additional downlink signals from the first cell station using a second configuration parameter.

[0013] In embodiments of the present invention, and in various aspects and variations thereof, the configuration parameter includes one or more sets of parameter values ​​relating to the configuration of the communication. These are, for example, resources (e.g., resource blocks (defined by time, frequency, code, and / or spatial channel), spatial beams). These may also be other parameter values ​​such as a selected transmit mode, a selected modulation scheme, and a HARQ process. Furthermore, these can be combinations of resources and other configuration values. While many examples in the embodiments illustrate the instruction of allocated resources, these embodiments are further applicable to other configuration parameters.

[0014] According to a first variation of the first embodiment, after a receiver receives a TX limiting operation mode activation signal, which is a downlink signal sent directly by a first cell station that instructs or triggers the activation of the TX limiting operation mode, the controller starts the TX limiting operation mode.

[0015] In a second variant of the first embodiment combined with the first variant, the controller initiates TX limit operation mode when a transmit or receive operation satisfies one or more pre-configured signal strength / receive quality thresholds or one or more signal transmission failure thresholds, when the energy level of a wireless terminal falls below a specific threshold, or when a relay station is discovered.

[0016] In a third variant of the first embodiment combined with the first and / or second variant, the transmitter is adapted to transmit an initial signal to a first cell station and / or relay station that instructs or triggers the activation of the TX limiting operation mode.

[0017] In a fourth variant of the first embodiment, combined with one or more of the previous variations of the first embodiment, the controller is adapted to operate alternately according to a first operating mode and a second operating mode, which is a TX limiting operating mode. The receiver is adapted to receive, in a second operating mode, a second downlink signal transmitted directly by a first cell station, the second downlink signal carrying each second downlink control information, wherein at least one of the second downlink control information includes at least an indication of a third configuration parameter to be used by the wireless terminal to transmit an uplink signal directly to the first cell station, and at least one of the second downlink control information includes at least an indication of a fourth configuration parameter to be used by the wireless terminal to receive further downlink signals directly from the first cell station. The controller is adapted to generate uplink information. The transmitter is configured by the controller to transmit to the first cell station in a second operating mode using a third configuration parameter for direct communication to the first cell station, and the receiver is configured by the controller to receive further downlink signals directly from the first cell station using a fourth configuration parameter.

[0018] According to an alternative and more specific definition of the first embodiment, a wireless terminal for communication on a cellular network is proposed, wherein the cellular network comprises at least one first cell station serving a first cell and at least one relay station served by a second cell station serving a second cell. Wireless devices, A controller for operating wireless terminals alternately according to a first operating mode (direct operation mode) and a second operating mode (TX-restricted operation mode), Equipped with a receiver and a transmitter, The receiver is adapted to receive, in direct operation mode, a first downlink signal directly transmitted by a first cell station, the first downlink signal carrying each first downlink control information, wherein at least one of the first downlink control information includes at least an indication of a first allocated uplink resource to be used by the wireless terminal to directly transmit a first uplink signal to the first cell station, and at least one of the first downlink control information includes at least an indication of a first allocated downlink resource to be used by the wireless terminal to directly receive further downlink signals from the first cell station. A second downlink signal transmitted directly by a first cell station in TX-restricted operation mode, which includes at least an instruction, and is adapted to receive a second downlink signal carrying each second downlink control information, wherein at least one of the respective second downlink control information includes at least an instruction for a second resource to be used by a wireless terminal to transmit the second signal directly to a relay station, and at least one of the respective second downlink control information includes at least a second allocated downlink resource to be used by a wireless terminal to receive further downlink signals directly from the first cell station. The controller is adapted to generate uplink information. In direct operation mode, the transmitter is configured by the controller to transmit to the first cell station over a first allocated uplink resource for direct communication to the first cell station, and the receiver is configured by the controller to receive further downlink signals directly from the first cell station over a first allocated downlink resource. In TX-restricted operation mode, the transmitter is further configured by the controller to transmit a second signal to the relay station on a second resource that carries uplink information to be forwarded to a second cell station, and the receiver is further configured by the controller to receive additional downlink signals directly from the first cell station on a second allocated downlink resource.

[0019] Therefore, the wireless terminal of the first embodiment and its variations are capable of adapting their operation, for example, as needed or in accordance with certain commands from the network. In the first operating mode, the wireless terminal communicates directly with the first cell station. In the second operating mode, the wireless terminal still receives messages from the first cell station but does not send replies to the first cell station, instead sending them to a relay station. This thus allows for lower energy consumption and / or lower transmission power to be used when transmitting in the case where the relay station is closer to the wireless terminal than the first cell station. Furthermore, the resources to be used are still signaled by the first cell station on the downlink in this case. This avoids the need for the wireless terminal to detect whether it is connected to the relay station and whether control data is being sent to it by the relay station (which can be energy-consuming and slow), depending on the available downlink bandwidth of the relay station (i.e., sidelink bandwidth for downstream data) and the method of resource allocation used for sidelink transmission. Downlink data is transmitted directly by the first cell station, which therefore enables a more reliable, low-latency, high-data-rate connection than an indirect connection through a relay station. Messages (or information contained in messages) sent to a relay station can be forwarded to the network through the cell station serving the relay station.

[0020] The relay station is served by a first cell station in a first cell, i.e., the same cell as the wireless terminal (which means that the second cell station is also the first cell station), or optionally, in a different cell, and thus is served by a second cell station separate from the first cell station.

[0021] In a variation of the first aspect of the present invention, in the TX-limited operation mode, it is proposed that the transmitter be configured to refrain from transmitting on the resources used for direct uplink communication to the first cell station.

[0022] This means that during the TX-limited operation mode, the wireless terminal does not use the resources allocated for direct transmission to the first cell station. Thus, for example, since a scheduling request is not sent directly to the first cell station, information is not sent to the first cell station in the control plane. This is typically done by simply blocking, for example, resources (frequency carriers, time slots, and / or codes (e.g., scrambling, channelization, or spreading codes depending on the system type)) dedicated to transmission to the first cell station. In another example, transmission on these resources is disabled by actively limiting the transmission range by blocking the transmission power exceeding a threshold. This threshold is typically lower than the maximum transmission power achievable in the first operation mode.

[0023] In a first variation of the first aspect of the present invention, the receiver is further adapted to receive a third downlink signal sent by the first cell station, the third downlink signal carrying third downlink control information, the third downlink control information including at least an indication of the downlink resources on which user data transmitted by the first cell station is expected to be received, and the controller is adapted to configure the receiver to receive the user data. This variation is also applicable to the previously discussed variations.

[0024] Upon receiving user data, the wireless terminal decodes the user data. The controller then generates uplink information that may include an acknowledgment message based on a determination of whether the user data was successfully decoded, and the acknowledgment message is transmitted by the transmitter to the first cell station using, for example, an uplink resource instruction assigned by a second configuration parameter when the controller is operating in direct operation mode, or to the relay station using a first configuration parameter such as a first resource when the controller is operating in TX-restricted operation mode.

[0025] In a second variation of the first aspect of the present invention, which can be combined with any of the previously discussed variations, the wireless terminal includes a buffer memory configured to buffer uplink data to be transmitted, and the uplink information includes a buffer status report indicating the amount of uplink information currently buffered in the buffer memory.

[0026] Therefore, in the second operating mode, a Buffer Status Report (BSR) is transmitted indirectly to the network via a relay station, which then forwards the BSR to its respective serving cell station. The Buffer Status Report is typically a MAC control element indicating the amount of buffered data awaiting transmission for one or more logical channels or logical channel groups. This allows the network scheduler to allocate resources for transmission according to the needs of the wireless terminals. The BSR can be in a different format, for example, depending on the size of the resources available for the transmission of the BSR itself, or depending on whether the BSR is transmitted via an uplink or a sidelink.

[0027] In an alternative form of the second variation, the buffer status report is received by a relay station, which then processes the buffer status report. Such processing includes, for example, generating a new buffer status report that represents the amount of data (or corresponding resource needs) accumulated in each buffer of some or all of the wireless terminals that the relay station is acting as a relay for.

[0028] In a third variation of the first aspect of the present invention, which can be combined with any of the previously discussed variations, the uplink information includes at least one uplink user data packet, the user data packet being sent directly to the first cell station in a second operating mode, and the user data packet being forwarded by a relay station to the second cell station in a first operating mode.

[0029] As previously explained, each of these serving cell stations may be the first cell station if the relay station and wireless terminals are in the same cell and served by the same cell station. However, each serving cell station may be a different cell station. Furthermore, it is important to note that the relay station may indirectly forward messages to the network through at least one or more further relay stations in some more advanced examples of the present invention. The BSR may include the transmission of user data packets.

[0030] In a fourth variation of the first aspect of the present invention, which can be combined with a third variation, the receiver is adapted to receive further downlink control information, including an indication of whether the uplink user data packet has been successfully decoded.

[0031] Therefore, after transmitting user data packets (application layer information, IP packets, etc.) or control messages (BSR, etc.) to the relay station, the relay station forwards the user data packets or control messages to the network, for example, to a second cell station to which the relay station is connected. As previously described, the second cell station may actually be the first cell station, for example, if the relay station is in the first cell, or it may be a separate station if the relay station is in a different cell. The second cell station receives and decodes the user data packets or control messages, or verifies the integrity of the user data packets or control messages (for example, using cyclic redundancy check (CRC), message authentication code, or message integrity code). In an exemplary embodiment, if the message is received correctly and / or decoded successfully, the second cell station causes the first cell station to send an authorization to the wireless terminal. This implies sending an instruction to send the authorization via the backhaul channel (for example, via the X2 interface linking the cell stations, or via the core network). Alternatively, the second cell station forwards the received user data packet or control message to the first cell station, which decodes or verifies the integrity of the user data packet or control message and, if successful, generates an acknowledgment. Since the acknowledgment is directly receivable from the first cell station, the wireless terminal does not need to detect control resources from the relay station to obtain the acknowledgment. However, it should be noted that a HARQ timer (which triggers a retransmission if it expires without a positive acknowledgment) must be adapted to this forwarding architecture. For example, this HARQ timer could correlate with the number of hops required to reach the first cell station (i.e., including the backhaul link). Alternatively, as another example, no HARQ-based retransmissions are sent by the wireless terminal, and instead, only PDCP or IP layer-based retransmissions are sent.

[0032] User data packets or control messages may also be initially acknowledged by the relay station at the MAC level, for example, simply to indicate that the first hop of transmission was successful. Higher-layer acknowledgments (e.g., PDCP layer or application layer) are sent directly and separately from the first cell station after the user data packet has been forwarded by the relay station.

[0033] According to a second aspect of the present invention as described in claim 12, a cellular communication system is proposed, and the cellular communication system is A first cell station serving a first cell, At least one relay station served by the second cell station serving the second cell, Wireless terminals served by the first cell station and Equipped with, A first cell station comprises a first cell station transmitter for directly transmitting a first downlink signal carrying first downlink control information to a wireless terminal, wherein the first downlink control information includes at least an indication of first configuration parameters to be used by the wireless terminal to transmit the signal to a relay station. A second cell station comprises a second cell station transmitter for transmitting a second downlink signal carrying second downlink control information to a relay station, wherein the second downlink control information includes at least an indication of a second configuration parameter to be used by the relay station to receive a signal from a wireless terminal. The first and second configuration parameters overlap at least partially, A wireless terminal comprises a wireless terminal controller adapted to generate uplink information, and a wireless terminal transmitter configured by the wireless terminal controller to transmit a message carrying the uplink information to a relay station using a first configuration parameter. The relay station comprises a relay station receiver adapted to receive the message using a second configuration parameter.

[0034] Thus, according to the second aspect of the present invention, for example, the first and second configuration parameters, which are the first and second resources, or some other parameter values, at least partially overlap. In some variations of this second aspect, the first and second resources correspond to each other. However, in some exemplary embodiments of the present invention, the second resource can actually be a large set of resources, such as a resource pool, to be monitored by a relay station. In this case, the first resource is included in the second pool, i.e., it is one resource element from the resource pool.

[0035] However, in some further variations, the first cell station and the second cell station may use different (e.g., their own) time / clock references, which may be slightly different. This means that the first resource and the second resource are misaligned. In this case, this can result in, for example, the time of the second resource being slightly too short, i.e., while they end at time t1, the transmission in the first resource ends at time t2, where t1 < t2. Conversely, the second resource may start slightly too late, i.e., while they start at time t3, the transmission in the first resource starts at time t4, where t3 > t4. Due to these examples, the relay station fails to perform part of the transmission. To prevent this problem, some countermeasures are added. As an example, the wireless terminal repeats its transmission message multiple times. Further, if configured like this, the relay station starts receiving slightly before its signaling resource slot to account for the clock difference.

[0036] Alternatively, the first cell station emits a time synchronization signal that can be received by the wireless terminal, while the relay station also emits that time synchronization signal that can be received by the wireless terminal. Thus, the wireless terminal can adjust the time offset between the downstream communication (sent, for example, via sidelink) and the upstream communication, and thus can be synchronized with the time reference of the first cell station for reception and the time reference of the relay station for transmission.

[0037] Another solution to the aforementioned problem regarding different time standards is the use of signaled resources that are slightly different (e.g., in length) from the actual resources used. For example, when the first and second cell stations use different resource configurations / numerology.

[0038] In an alternative and more specific definition of a second aspect of the present invention, the controller of the wireless terminal is configured to operate alternately according to a first operating mode (direct operating mode) and a second operating mode (TX-restricted operating mode), the wireless terminal receives a first downlink signal directly transmitted by a first cell station, the first downlink signal carrying each first downlink control information, at least one of the first downlink control information includes at least an indication of a first allocated uplink resource to be used by the wireless terminal transmitter to directly transmit a first uplink signal to the first cell station, and at least one of the first downlink control information includes at least an indication of a first allocated downlink resource to be used by the wireless terminal receiver to directly receive further downlink signals from the first cell station, the TX-restricted operating mode receives a second downlink signal directly transmitted by the first cell station, the second downlink signal carrying each second downlink control information includes at least an indication of a first allocated downlink resource to be used by the wireless terminal receiver to directly receive further downlink signals from the first cell station A modified wireless terminal receiver is provided, which receives a second downlink signal carrying downlink control information, wherein at least one of each of the second downlink control information includes at least an instruction for a second resource to be used by a wireless terminal transmitter to directly transmit the second signal to a relay station, and at least one of each of the second downlink control information includes at least a second allocated downlink resource to be used by a wireless terminal receiver to directly receive further downlink signals from a first cell station, and the controller is modified to generate uplink information, and in direct operation mode, the wireless terminal transmitter is configured by the wireless terminal controller to transmit to the first cell station over a first allocated uplink resource for direct communication to the first cell station, and the wireless terminal receiver is configured by the wireless terminal controller to directly receive further downlink signals from the first cell station over a first allocated downlink resource, In TX-restricted operation mode, the wireless terminal transmitter is further configured by the wireless terminal controller to transmit a second signal to the relay station on a second resource that carries uplink information to be forwarded to a second cell station, and the wireless terminal receiver is further configured by the wireless terminal controller to receive further downlink signals directly from the first cell station on a second allocated downlink resource.

[0039] According to a second variation of a second aspect of the present invention combined with the first variation, the relay station comprises a relay station transmitter for transmitting a relay message including the uplink information to a second cell station.

[0040] According to a third variation of a second aspect of the present invention combined with a first or second variation, the second cell station is adapted to transmit a third downlink signal to a relay station carrying third downlink control information, the third downlink control information including at least an indication of a third configuration parameter to be used by the relay station to transmit a relay message to the second cell station.

[0041] Therefore, the network has the ability to fully control and schedule the resources allocated for transmission from wireless terminals to the network, and thus allocate resources for each hop of transmission to the cell station, for example. This typically means that the entire path for transmission (including multiple hops if multiple relay stations are used) is secured by a network scheduler located in the cell station. Depending on the architecture, a second cell station controls all uplink allocation from the relay stations to the network.

[0042] As previously described in relation to a first aspect of the present invention, the first cell station and the second cell station may be a single cell station.

[0043] According to a fourth variation of a second aspect of the present invention, the first downlink signal and the second downlink signal can be a single downlink signal received by the wireless terminal and the relay station. This further reduces the control signaling required for resource allocation for message transmission.

[0044] Similar to the fourth variation, and possibly in combination with the fourth variation, the second and third downlink signals may also be a single downlink signal received at the relay station. This further reduces allocation signaling, as a single signal is used for allocating upstream routes.

[0045] In a fifth variation of the second embodiment, combined with any of the variations discussed previously, the relay station comprises a relay station controller for determining whether a message has been properly received and / or properly decoded (for example, by verifying the integrity of the received message), and a relay station transmitter configured by the controller to transmit an acknowledgment message to a wireless terminal indicating whether the message has been properly received and / or decoded.

[0046] In a sixth variation of the second embodiment, combined with any of the previously discussed variations, the message carrying uplink information includes at least one uplink user data packet to be forwarded by the relay station to a second cell station.

[0047] In a seventh variation, which can be combined with a sixth variation, the first cell station transmitter is adapted to transmit an acknowledgment message indicating that the message has been correctly decoded by the second cell station or the first cell station.

[0048] According to a third aspect of the present invention, a relay station as described in claim 18 is proposed, which operates in a cellular communication network having at least one first cell station and a wireless terminal served by the first cell station, The relay station is served by a second cell station that serves the second cell. The relay station, A relay station receiver adapted to receive a second downlink signal from a second cell station carrying second downlink control information, wherein the second downlink control information includes at least one instruction for a first configuration parameter for receiving a message from a wireless terminal, A relay station controller for controlling a relay station receiver to receive the message containing uplink information in a first configuration parameter, A relay station transmitter adapted to transfer uplink information in relay data messages to a second cell station. It is equipped with.

[0049] It should be noted that relay data messages may include control information and / or user data. Furthermore, relay data messages may include information that is the result of some processing of the uplink information, including the uplink information itself (which can also be control information and / or user data), or a combination of that information with other information, such as as described in the embodiments below.

[0050] In a first variation of a third aspect of the present invention, the relay station receiver is adapted to receive a third downlink signal from a second cell station carrying third downlink control information, the third downlink control information including at least an indication of an allocated uplink resource to be used by the relay station to transmit a relay message to the second cell station.

[0051] In a second variant of a third aspect of the present invention combined with the first variant, the relay station controller is adapted to determine whether a message has been properly received and / or properly decoded (for example, by verifying the integrity of the received message), and the relay station transmitter is configured by the relay station controller to transmit an acknowledgment message to a wireless terminal indicating whether the message has been properly received and / or decoded.

[0052] According to a fourth aspect of the present invention, a first cell station is proposed that serves the first cell described in claim 19 in a cellular communication system, and the cellular communication system is At least one relay station served by a second cell station serving a second cell, Wireless terminals served by the first cell station and Equipped with, The first cell station, A first cell station transmitter for transmitting a first downlink signal carrying first downlink control information to a wireless terminal, wherein the first downlink control information includes at least an indication of first configuration parameters to be used by the wireless terminal to transmit a message to a relay station, A first cell station controller for configuring a relay station with second downlink control information, wherein the second downlink control information includes at least instructions for a second configuration parameter to be used by the relay station to receive messages from a wireless terminal, and the first and second resources at least partially overlap the first cell station controller and It is equipped with.

[0053] In a first variation of a fourth aspect of the present invention, the configuration by a first cell station controller of a relay station includes the first cell station causing a second cell station to transmit a second downlink message to the relay station, which includes the second downlink control information.

[0054] However, it should be noted that, as in the other aspect of the present invention, the first cell station and the second cell station may be a single cell station. This is, for example, a case where the wireless terminal and the relay station are served by the same cell.

[0055] A fifth aspect of the present invention is proposed in claim 20 for operating a wireless terminal to communicate in a cellular network, wherein the cellular network has at least one relay station served by at least one first cell station serving a first cell and a second cell station serving a second cell. The method is, A wireless terminal receives a downlink signal transmitted by a first cell station, the downlink signal carrying downlink control information, wherein the downlink control information includes at least an indication of a first configuration parameter to be used by the wireless terminal to transmit a message to a relay station. The wireless terminal generates uplink information, A wireless terminal transmits a message carrying uplink information to a relay station using a first configuration parameter, wherein the uplink information is to be forwarded to a second cell station. It has.

[0056] According to a seventh aspect of the present invention, a computer program product is proposed which, when executed on a computer device, has coding means for producing steps of the method of a sixth aspect of the present invention.

[0057] It should be noted that the above-mentioned devices are implemented based on individual hardware circuit equipment, which involves the arrangement of individual hardware components, integrated chips, or chip modules, or on signal processing devices or chips controlled by software routines or programs stored in memory, written on computer-readable media, or downloaded from a network such as the Internet.

[0058] It should be understood that wireless terminals, systems, relay stations, cell stations, and methods have similar, corresponding, and / or identical preferred embodiments, particularly as defined in the dependent claims.

[0059] It should be understood that preferred embodiments of the present invention may also be dependent claims with each independent claim or any combination of embodiments.

[0060] These and other aspects of the present invention will become apparent from the embodiments described below and will be explained with reference to the embodiments described below. [Brief explanation of the drawing]

[0061] [Figure 1A] This is a block diagram representing a network in which the present invention can be implemented. [Figure 1B] This is a block diagram representing a multi-hop network in which the present invention can be implemented. [Figure 2A] This is a block diagram representing the layered model of the user plane using a relay architecture. [Figure 2B] This is a block diagram representing the layer model of the control plane using a relay architecture. [Figure 3] This is a block diagram representing a network using a multi-hop relay architecture for cell stations. [Figure 4] This is a block diagram representing a network according to the first embodiment of the present invention. [Figure 5]This is a flowchart illustrating the operation of the network in the first embodiment. [Figure 6] This is a block diagram representing a wireless terminal according to the first embodiment. [Figure 7] This is a block diagram representing a relay station according to the first embodiment. [Figure 8] This is a block diagram representing a cell station according to the first embodiment. [Figure 9] This is a block diagram representing a network according to a second embodiment of the present invention. [Figure 10] This is a block diagram representing a network according to a third embodiment of the present invention. [Figure 11] This is a block diagram representing a network according to a fourth embodiment of the present invention. [Figure 12] This is a block diagram representing a network according to a fifth embodiment of the present invention. [Figure 13] This is a block diagram representing a network using dual connectivity. [Modes for carrying out the invention]

[0062] In the following, embodiments are described in the context of 3GPP® cellular networks, but these embodiments may be applicable to other types of networks. As previously described, cells are served by cellular base stations, which are called “eNB” (4G term) and “gNB” (5G term) in 3GPP®. eNB / gNB are part of the Radio Access Network RAN ​​and interface to the functions of the Core Network (CN). “UE” stands for “User Equipment” and is the standard 3GPP® term for wireless client devices or the specific roles played by such devices. The term “Node” is used to represent a UE or gNB / eNB. “NF” stands for Network Function of the CN.

[0063] "Indirect network connection" is as defined in TS22.261. "D2D" is device-to-device communication, and "PC5" is an interface for using sidelink communication as defined by V2X (TS23.287) or ProSe (TS23.303, TS23.304, and TS38.300). "UL" is used for uplink Uu communication as defined in TS38.300, "DL" is used for downlink Uu communication as defined in TS38.300, and "Sidelink" or "SL" is used for sidelink communication as defined in TS38.300.

[0064] In the following description, “upstream” or “uplink” is used for data flows destined to go to a cell station, such as a gNB, while “downstream” or “downlink” is used for data flows from a gNB destined to go to an UE in the RAN. “User data” is used for any type of user data or application data that is not related to the management or operation of cellular network functions (typically at or above the IP layer). Upstream transmission involves an indirect network connection via one or more relay stations, so that the signal / message is first sent to a relay station, which then forwards the signal / message to the gNB. Relay stations support UL (Uu interface) and / or SL (PC5 interface). Therefore, upstream transmission occurs over UL (Uu interface) and / or SL (PC5 interface), depending on the network configuration and context. In the context of this patent application, since wireless terminals are capable of receiving signals / messages directly from cell stations (even when operating in a transmit mode restricted to sending upstream signals / messages), unless otherwise specified, the term "downlink" is typically used for transmissions over DL (Uu interface) and the term "downstream" is typically used for indirect communication via relay stations, and therefore, transmissions may also occur over SL (PC5 interface), depending on the network configuration and context.

[0065] In the cellular network in which the present invention is implemented, each cell 10 is served by a base station 100, as previously mentioned with reference to Figure 1A. There are several secondary stations near cell 10 and near base station 100. At least some of these secondary stations can communicate directly with base station 100. Furthermore, some of the secondary stations can function as relay stations 120, since they include the function of relaying communication between base station 100 and another secondary station 110. This relay function helps, for example, extend the coverage of cell 10 to a secondary station 110 outside of coverage (OoC). Relay stations 120 can also be mobile stations (e.g., UEs) or different types of devices. This cellular network is, for example, a 4G or 5G network, or some other type of cellular network. Since 4G and 5G networks include the possibility of relaying by UEs with sidelink capabilities, relay stations 120 and secondary stations 110 in Figure 1A are UEs with sidelink capabilities in this example. Although Figure 1A is limited to a single-hop architecture, various embodiments of the present invention described herein can also be adapted to the case of a multi-hop architecture, as shown in Figure 1B.

[0066] Direct communication with a base station has several drawbacks, or may not even be possible for a period of time. Direct communication with a base station requires high energy consumption and / or high energy peaks to transmit messages with sufficient radio transmit power, which is unacceptable for wearable UEs or IoT UEs (wireless, typically battery-powered). Sometimes, conditions can even worsen (due to interference or further attenuation), making transmission impossible. In practice, a UE (e.g., an IoT device) has limited radio transmit power and therefore, when the UE is far away, moves out of range, and / or is subjected to interference or has new obstacles in the transmission path, it may no longer be able to reach the base station (gNB) using the available and / or selected transmit mode. On the other hand, the UE may still receive transmissions from the gNB despite worsened conditions, thanks to, for example, more flexible and robust transmit modes at the gNB, or higher available transmit power.

[0067] The current solution, as defined by 3GPP®, allows wireless terminals acting as fully or partially out-of-coverage (OoC) remote UEs (e.g., intermittently out of coverage, or consequently, transmission to cell stations (e.g., gNBs) lacks sufficient signal quality, leading to numerous retries or message loss) to communicate via relay stations that act as relay UEs to send upstream data or receive downstream data. However, all communication with remote UEs currently takes place via sidelink (SL) channels, using a self-scheduling method for resource selection (mode 2) for the remote UEs. This self-scheduling has several problems. - Self-scheduling requires the remote UE to broadly "sens" designated sidelink time / frequency resources to determine when it can send to or receive messages from the relay UE. This sensing increases energy consumption. This high energy consumption for wearable UEs or IoT UEs (wireless, typically battery-powered) is unacceptable due to the limitations of portable devices, and especially for IoT devices. - Self-scheduling restricts the remote UE to using only pre-configured resources, the so-called sidelink resource pool, for sending sidelinks to the relay UE, while in reality there are other, more optimal resources available that the remote UE is not currently authorized to use. Furthermore, remote UEs must compete for (potentially limited) sidelink resources with other UEs outside their coverage (e.g., other OoC remote UEs connected to the same relay UE), or with OoC UEs that rely on sidelink communication for their applications, such as ProSe D2D or V2X D2D applications. Many users of sidelink spectral resources, combined with a self-scheduling approach (without central orchestration by gNB for OoC UEs), can increase radio transmit collisions and the probability of transmit failures with relay UEs. - The potentially limited bandwidth available for downstream data (via relay UEs) to indirectly connected remote UEs may, in certain cases, be insufficient for downstream data capacity. a. For example, one reason for this bottleneck is that the resources allocated for sidelink (SL) communication required by the relay UE to send data to the remote UE are a very limited subset of the entire set of available cellular resources. b. Another reason is that the relay UE needs to serve other remote UEs simultaneously, and therefore the relay UE's limited resources (spectrum, processing time, buffer memory, etc.) need to be shared across multiple devices. Other remote UEs have a higher priority in order to be served by the relay. Furthermore, if the relay UE needs to apply the DRX feature for power saving purposes, or wants to do so, it may occur that the remote UE sends to the relay UE while the relay UE is in its DRX sleep / inactive state, or the remote UE must wait until the relay UE's DRX is active before sending. This can increase latency or, in some cases, result in partial data loss. - There is a possibility of packet collisions due to resource allocation (mode 2) duplication when a remote UE is outside the coverage area and therefore no resources are scheduled for the remote UE to send.

[0068] A known solution for scheduling SL resources for relay UEs directly connected to a gNB is described in TR37.985 v16.0. The gNB sends a DCI format 3_0 / 3_1 message to the relay UE, which then makes the SL available on the indicated resource. However, the inventors of this invention recognize the following disadvantages of this known solution. ● Because DCI messages are only directed to the relay UE, the remote UE is unaware of the scheduled resource. Therefore, the remote UE does not know when to prepare to receive the SL from the relay UE. ● This known solution cannot be used to schedule resources for transmission for remote UEs. In fact, under the current specification, scheduling messages are not sent to OoC UEs, including partially OoC UEs such as transmit-limiting UEs (as will be described in more detail later). Therefore, remote UEs do not know when / how best to send in SL so that relay UEs receive scheduling messages, and remote UEs can perform as poorly as self-scheduling.

[0069] The proposed embodiments of the present invention overcome these shortcomings by defining scheduling and data transmission methods so that both the relay UE and the remote UE are informed of the resources to be used for communication, for example, in situations where the connectivity of the remote UE is limited.

[0070] It should be understood that limited connectivity may be due to external conditions and design / operational choices of the remote UE. For example, a remote UE may encounter limited connectivity due to its location (e.g., cell edge or inside a building) where direct uplink transmission to the base station would be too expensive in terms of energy or power, or due to its capacity (low remaining battery charge, low-power devices such as energy harvesting terminals), or it may lead to many retries or message loss due to insufficient signal quality. In another example, a remote UE may be used in a location where the transmit level cannot exceed a threshold (hospital, laboratory where radiation levels must remain within a given range). These limitations correspond to TX-limited wireless terminals that do not (or preferably do not) have the ability to transmit directly to the cell station.

[0071] Such asymmetrical situations where a reply cannot be sent arise due to inherent TX limitations in the wireless terminal (or remote UE), such as one or more of the following specific examples: 1. For example, the maximum allowable peak current drain from a wireless terminal battery due to its small battery form factor, such as a coin cell, or due to the battery's inherent chemical properties. 2. Maximum allowable transmit power of wireless terminal radios by using, for example, low-cost / low-power / compact form factor wireless modules. 3. For example, a limited duty cycle available for high-power transmission when the high-power Tx mode is powered by a (ultra)capacitor charged via a battery with limited output current or through energy harvesting. 4. Suboptimal antenna designs, such as a limited number of antennas due to the small form factor of the wireless terminal, or low effective radiated Tx power. While a cell station compensates for this limitation by increasing its transmit power and / or increasing signal repetition or other means, the wireless terminal cannot compensate for this limitation due to one or more of limitations 1, 2, 3, or 8. 5. Unoptimal device placements that interfere with wireless terminal transmission, such as embedded UE or M2M modules located in basements, deep inside buildings, etc. While cell stations compensate for this limitation by increasing their transmit power and / or increasing signal repetition or other means, wireless terminals cannot compensate because they are limited by one or more of the limitations 1, 2, 3, or 8, or because their location (e.g., human body) restricts their transmit power. 6. For example, the limited number of antennas or capacity for signal processing at the wireless terminal may prevent it from performing (effective) Tx beam steering toward the cell station. The cell station may compensate for this limitation by increasing its transmit power and / or increasing signal repetition or other means, but the wireless terminal may not be able to compensate due to one or more of the limitations 1, 2, 3, or 8. 7. Generally, an "asymmetrical" configuration between the cell station transmitter and the wireless terminal transmitter. 8. Limited support in the UE for coverage expansion modes, such as increasing the number of iterations to send messages to cell stations. 9. The transmit and receive frequencies are different (e.g., as in an FDD), or the modulation for the transmit / receive signals is different, and the transmit-receive link budget is different. 10. The wireless terminal has limited energy available for transmission (e.g., low remaining battery power or the energy harvesting capacity is not yet fully charged), but still has an urgent / important message to send (e.g., an emergency SMS).

[0072] Therefore, as described above, one object of the present invention in the case of a TX-restricted wireless terminal is to solve the above problem for the specific case in which a wireless terminal is capable of receiving transmissions from a cell station (i.e., channels on DL) but is not capable of physically transmitting replies (i.e., via UL), or is capable in principle of transmitting replies but does not do so to conserve energy or for other reasons (e.g., possible local usage rules).

[0073] Conversely, restricted connections further include Rx-restricted stations that have the ability to transmit directly to cell stations but cannot receive directly. This can be due to a low-sensitivity receiver or local interference (e.g., coexistence with a nearby Wi-Fi network).

[0074] The "asymmetry" aspect mentioned in point 7 above concerns the difference between the cell station transmitter and the wireless terminal transmitter, which, in some situations, can make it more likely for the cell station to transmit to the wireless terminal than the other way around. 1. High power (dBm) for transmission available at cell stations vs. low power at wireless terminals 2. Different frequency bands used for transmission and reception, where the link budget for downlink is higher than that for uplink. 3. A cell station powered by a wall outlet and a battery-powered (or energy harvesting) wireless terminal.

[0075] From the perspective of these cases, the inventors recognize that the above list of limitations will be relatively common in the future as 5G is increasingly adopted in wearable, low-power, and IoT devices.

[0076] Other work in 3GPP® discussed in TR23.733 and TR36.746 includes considerations of architectural enhancements to enable wireless terminals, such as IoT devices (in the role of remote UEs), to operate at very low power by connecting to wider networks using relay stations that function as relay UEs. Because the relay UEs are physically very close, they can be reached using very low-power transmissions. These discussions lead to several new relay architectures, including a Layer 2 (L2) relay architecture. Layer 2 of the OSI model corresponds to the Data Link Layer or Radio Layer 2 in 3GPP® (RLC, MAC, PDCP), while Layer 3 of the OSI model corresponds to the Network Layer (Internet Protocol Layer). Unlike ProSe 4G relay, which operates at the Application Layer (L3, roughly the Internet Protocol IP Layer), this L2 relay architecture is intended to provide end-to-end IP packet and PDCP packet transmission to and from wireless terminals, as shown in Figure 2A regarding the user plane stack. Similarly, as can be seen in Figure 2B regarding the control plane stack, an L2 relay for control plane data is proposed.

[0077] Such an architecture allows a wireless terminal acting as a remote UE to be directly visible as a registered entity in the core network. This offers several advantages for applications such as monitoring or billing, and for improved control by cell stations via the wireless terminal. Furthermore, the wireless terminal can access all the functions of the core network as if it were directly connected. Note that alternative relay architectures exist, such as the proposal for Layer 3 (L3) relay in ProSe 5G (user plane only) in TR23.752, which are very similar to those in the case of 4G. In addition, other types of relay devices have been discussed or are being discussed (see, for example, TR22.859), such as using a UE as a gateway UE (e.g., a mobile phone or residential gateway) to relay traffic from personal IoT devices (e.g., wearables, in-home devices) to the 5G network.

[0078] Furthermore, 3GPP® is working further on new features discussed in TR38.874 regarding Integrated Access and Backhaul (IAB) to enable relaying between cell stations. The goal of IAB is to make it easier to expand the coverage area of ​​5G radio access networks through the deployment of additional intermediate wirelessly connected cell stations or smaller cells. The main difference from UE-based relays (such as Sidelink) is that in IAB, the device is a highly sophisticated device with many resources, whereas in UE-based relays, the wireless terminal can be a very low-power, resource-limited device with very few resources to dedicate to functioning as a relay station. Additionally, in IAB, cell stations are typically owned and operated by the same network infrastructure provider, whereas in the case of UE-based relays, the relay stations acting as relay UEs are typically owned by many different individuals with different subscriptions for each mobile network operator. Furthermore, in the case of relay UEs, mobile network operators desire complete authority control over which UEs can function as relay UEs and which remote UEs and relay UEs are permitted access to the mobile network, whereas in IABs, this is seamlessly integrated within the core network. Mobile network operators also desire complete control over the resources / frequency that relay UEs can use for sidelink communication with remote UEs, whereas in IABs, intermediate nodes have more autonomy in scheduling resources for downlink devices. Note that in some cases (e.g., 3GPP® also discusses the use of automotive IAB nodes (see, e.g., TR22.839)), some of these characteristics and procedures (e.g., ownership, authorization, resource allocation) are more similar to relay UEs than to base stations.

[0079] As shown in Figure 3, this architecture uses a mechanism similar to a ProSe repeater, which allows IAB nodes to relay traffic for other IAB nodes to the IAB donor. Communication between IAB nodes uses a 5G-defined interface "F1," as defined in TS38.473, between a base station central unit (CU) and its linked distributed units (DUs), which is commonly used for distributed cell stations. For registration and some control information, the IAB node further includes mobile terminal / UE components.

[0080] However, these improvements fail to solve all of the previously mentioned problems, on the one hand, with sidelink scheduling, and on the other hand, with direct communication with base stations that require high energy consumption and are unreliable.

[0081] Accordingly, according to a first embodiment of the present invention, a cellular network is proposed, as shown in Figure 4, having a cell station 400, such as a gNB400 serving cell 40. Multiple secondary stations are included in this cell. A first type of secondary station 410 is a secondary station that encounters (or requests) a restricted connection. In this embodiment, this restricted connection corresponds to the transmission restrictions described previously, in the sense that direct transmission to the cell station is prevented (or blocked). This first type of secondary station is a wireless terminal, such as a remote UE410. A second type of secondary station, also located in the first cell in this example, functions as a relay station 420, i.e., has sufficient capacity and appropriate functionality to function as a repeater between the cell station and other secondary stations. These relay stations 420 are located between the cell station 400 and the first type of secondary station, i.e., the wireless terminal 410, or optionally, the second type of secondary station (i.e., relay station 420) in the case of a multi-hop system (not shown in Figure 4). This relay station 420 functions as a relay UE 420 solely for upstream flow. This first embodiment enables upstream data flow 411 and downlink data flow 401 (including, for example, both data traffic and control information transmitted over their respective channels). According to this embodiment, a direct radio link 401 (DL) from the cell station 400 to the wireless terminal 410 and the relay station 420 is used to schedule resources to the wireless terminal and the relay station and to publish downlink data. An indirect link 411 between the wireless terminal 410 and the cell station 400 through the relay station 420 is available for upstream data. Another downlink direct link 402 between the cell station 400 and the relay station 420 is used, on the one hand, to schedule upstream resources (e.g., sidelink resources) to be used between the wireless terminal 410 and the relay station 420, and on the other hand, to schedule uplink resources to be used between the relay station 420 and the cell station 400. Furthermore, relay station 420 uses its own uplink connection 403 for transmitting to cell station 400.In Figure 4, this uplink connection 403 is direct to the cell station 400. However, in the case of a multi-hop relay system, this uplink connection 403 is indirect. Note that in the various embodiments below, the upstream link 411 is logically included in the uplink connection 403 (allowing for greater flexibility in the connection). Alternatively, the operation of the various embodiments below can be adapted to maintain links 411 and 403 as separate logical (or possibly physical) links.

[0082] Therefore, it is proposed that the cellular wireless communication system includes at least one cell station 400, at least one secondary station 420 (e.g., a relay UE) functioning as a relay station 420, and at least one wireless terminal 410 (e.g., functioning as a remote UE). In this embodiment, the cell station 400 is capable of transmitting one or more communication resource reserve messages via downlink direct links 401 and 402 to indicate at least one of the following: - Downlink resources, also known as "DLresources," for future downlink data transmission directly from cell station 400 to wireless terminal 410. - Upstream resources, also known as "Us resources," for future upstream data transmission from wireless terminal 410 via SL and / or UL, and - Upstream resources for reception by the relay station, also called "Us-Rx resources," for receiving upstream data transmissions from wireless terminals 410, typically via SL and / or UL, in a secondary station 420 that functions as a relay station 420.

[0083] Uplink and upstream resources are either the same, based on the same resource pool, or based on separate resource pools. Uplink and upstream resources are not distinguishable by the wireless terminal 410 or the relay station 420 (this is the case, for example, when uplink resources are shared with the relay station to allow the relay station 420 to operate on behalf of the cell station, as will be described later). However, typically, uplink and upstream resources are distinguishable, and therefore, a cell station can indicate what type of cell station it is, for example, by using different DCI formats or different RRC messages. As an option (applicable to any other embodiment), the first cell station schedules both direct uplink resources (e.g., for communication via the Uu interface) and upstream resources (e.g., for communication via a sidelink, e.g., to a relay station) for the wireless terminal 410, and / or sends information about both the uplink and upstream resources to the wireless terminal in the first message, and / or sends configuration information about the conditions or thresholds under which the uplink resources and upstream resources should be used. Upon receiving both sets of resources, the wireless terminal sends a copy of the message / signal in both the uplink and upstream resources, or selects which resources to use based on the configuration information received from the cell station about the conditions or thresholds to apply, or based on pre-configured conditions or thresholds (e.g., stored in the USIM). These conditions / thresholds are the same as or overlap with the conditions / thresholds that the wireless terminal uses to determine whether it should operate or be required to operate in TX restricted mode.If a wireless terminal decides to operate in TX-restricted mode, it will communicate with the relay station using upstream resources rather than uplink resources, and will adjust the wireless terminal's transmit power depending on whether uplink or upstream resources are used, and / or whether the wireless terminal is configured by the cell station as either uplink or upstream resources. The cell station configures the wireless terminal (e.g., through control signals / messages, e.g., as part of SIB, RRC, or DCI signals / messages, or as part of UE policy information) with information about transmit power limits (e.g., minimum or maximum) and / or information about recommended transmit power to be used for different modes / situations / coverage levels / signal quality thresholds in which the device (e.g., a wireless terminal operating in TX-restricted mode) operates, for different (type) resources (e.g., uplink via Uu or upstream via sidelink), for different destinations (e.g., identified through a given identifier if a specific relay station should be used). The wireless terminal uses this configuration information to determine what transmit power to use.

[0084] It should be noted that this architecture is part of a special operating mode, and different architectures are typically used, such as the conventional architecture with a direct duplex link between the wireless terminal and the cell station. As will be detailed later, certain operating conditions or other events trigger the network, cell stations, relay stations, and / or wireless terminals to operate in this special operating mode (i.e., TX-restricted mode).

[0085] In any case, this architecture includes a mechanism for operating a secondary station, which is a wireless terminal 410 such as a remote UE, to communicate with the cell station 400 within the cellular network. This first cell station 400 serves the first cell 40. Furthermore, in this cell, at least one other secondary station 420 can operate as a relay station 420. As depicted in Figure 5, the mechanism includes the following steps. S51: The first cell station 400 sends a first message to the wireless terminal 410 that carries first downlink control information, including instructions for the allocated upstream resources. S52: The first cell station 400 sends at least one second message to the relay station 420 carrying second downlink control information. This second downlink control information is carried by one or more messages and includes information about upstream-allocated resources that a wireless terminal intends to send the message to the relay station 420. The second downlink control information further includes a message for allocating resources that should be used by the relay station 420 when forwarding the message. S53: The first message is detected by the wireless terminal 410, which decodes the message to obtain instructions for the allocated upstream resource. This allocated resource is available to the wireless terminal 410 to transmit the upstream signal to the relay station 420. S54: The wireless terminal 410 generates uplink information to be included in the message (i.e., information that is transmitted directly to the gNB via the Uu interface in normal bidirectional communication mode, e.g., user data) and uses the allocated upstream resources to send an upstream signal carrying the message to the relay station 420. Note that the uplink information is intended to be forwarded to the cell station 400. For this purpose, the uplink information is attached / pre-added / updated / multiplexed with information about the relay station (e.g., the relay station's L2 identifier or other identifier) ​​as part of the upstream message. S55: Relay station 420 receives messages from wireless terminal 410 on upstream resources allocated by cell station 400. S56: Relay station 420 optionally processes messages if necessary and forwards uplink information (or upstream signals / messages) to cell station 400.

[0086] In this embodiment, only one cell station 400 is included, but this mechanism can be adapted to cases where two or more cell stations need to be in operation. As will be detailed in further embodiments, for example, this is the case when, for example, a relay station is in a different cell and the relay station is served by another station rather than by cell station 400. As will be detailed later, the first cell station 400 undertakes to send a message to the wireless terminal 410 containing resource allocations (e.g., Us resources and / or Ds resources), while the other station transmits resource allocations to the relay station 420, such as UL resources and Us-Rx resources (for UL and coming in via SL from the wireless terminal, respectively).

[0087] It should be noted that the messages sent in step S51 and the messages sent in step S52 are merged (for example, bundled or encoded together in a single message using a common identifier for both the relay station 420 and the wireless terminal 410). Alternatively, as described above, these messages that allocate resources for the wireless terminal 410 to transmit and for the relay station to receive are sent via two separate messages decoded by both UEs. These messages can be sent by the first cell station 400, or in the case of two cell stations, by either one of the cell stations, or each message can be sent by one of the cell stations.

[0088] Furthermore, the first cell station 400 directly signals the wireless terminal to the scheduled downlink transmission. In this example, this signaling occurs within the same frame as the downlink transmission. Thus, the wireless terminal 410 is able to receive downlink data on the DL resource signaled by the first cell station and transmit upstream data on the allocated Us resource. This upstream data includes, for example, user data destined to flow into or beyond the core network, or at least one of the following: user data destined to flow into or beyond the core network, or feedback data such as an acknowledgment (ACK / NACK) indicating whether the wireless terminal 410 has correctly received downlink data previously sent directly to the wireless terminal 410 by the first cell station 400.

[0089] Optionally, as soon as the upstream signal in step S54 is received, the relay station 420 sends acknowledgment data (e.g., HARQ signal) to the wireless terminal 410. This acknowledgment data therefore indicates whether the data signal was received correctly or incorrectly. For this purpose, the first cell station 400 includes HARQ process information (e.g., HARQ process ID, timing / resource information) in the second downlink control information, for example, in step S52. In this example, the relay station 420 can act on behalf of the first cell station to send HARQ feedback information back to the wireless terminal 410. The first cell station further provides several security certificates or information about the type, format, encoding, scrambling, or content of the signal or message (for example, as part of the second downlink control information) to enable the relay station 420 to verify the integrity of the message or to (partially) decode the message / signal, and further provides instruction / policy information that, under certain conditions, permits the relay station 420 to send approval data to the wireless terminal (410) (for example, if the CRC or message integrity code / message authentication code is verified to be correct). The relay station 420 uses the information received from the first cell station to perform some processing on the upstream signal / message received from the wireless terminal 410, and if the result of this processing satisfies one or more conditions, sends approval data to the wireless terminal 410. Alternatively, the relay station 420 first forwards the received upstream signal / message (or uplink information to be added to a different message after processing) to the first cell station, and the first cell station, upon successful reception / decoding / integrity verification of the forwarded upstream signal / message (or a different message containing uplink information), sends the signal / message back to the relay station 420 (instead of sending the acknowledgment data directly to the wireless terminal 410), and so the relay station 420 subsequently sends the acknowledgment data to the wireless terminal 410.

[0090] It should be noted that the upstream signal in step S54, sent over the allocated Us resource, may be incidentally received directly by the first cell station 400 (for example, if channel conditions momentarily improve). Therefore, the data sent in step S54 is actually transmittable directly to the cell station 400, and the link to the relay station 420 can serve as a backup in case the direct transmit power level is insufficient. This is particularly relevant in the case where the wireless terminal 410 is on the edge of the Tx connection to the cell station 400, and its transmission may also be correctly received by the first cell station 400. In that case, the cell station 400 can directly process the upstream signal / message containing uplink information. The cell station 400 informs the relay station 420 (for example, through a second control signal) that the upstream signal (identified, for example, by its upstream resource, message identifier, or other part of the message) has already been correctly received directly by the first cell station 400. The relay station 420 then either abandons this message, avoids sending this message to the cell station 400, or avoids sending the approval data to the wireless terminal 410.

[0091] As mentioned in step S56, relay station 420 can relay the uplink data received from wireless terminal 410 upstream to its upstream cell station via one or more hops. There is HARQ feedback at each hop. The uplink data is then finally received by the first cell station 400. If the data contains upstream user data, the receiving cell station directly sends back feedback data, such as an ACK / NACK, to the wireless terminal 410 in a future downlink (DL) transmission using new Ds resources, indicating whether the user data was successfully received, for example. If the user data was not received correctly, feedback data, such as a NACK, indicates to the wireless terminal 410 that at least a portion of the previously transmitted data is missing. Cell station 400 then directly schedules a retransmission of the data by the wireless terminal 410. This can be done by allocating future Us resources. The retransmission is then relayed, possibly, through relay station 420.

[0092] In a particular variation of this embodiment, the cell station instructs a TX-limited wireless terminal to operate with a sidelink mode 2 resource allocation (for example, through an SIB / RRC message sent as part of a first or second downlink signal), and simultaneously, the TX-limited wireless terminal uses the sidelink mode 2 resource allocation instead of the scheduled upstream or uplink resources. As previously mentioned, the wireless terminal limits or reduces its transmit power when using these mode 2 resources in the TX-limited state.

[0093] According to the first embodiment, and again referring hereto to Figure 6, the wireless terminal, which functions as a wireless terminal 410, typically comprises an antenna 61 or antenna array (for example, in the case of a MIMO-compatible wireless terminal). This antenna 61 is coupled to a communication unit 62 comprising a receiver 621 and a transmitter 622. The communication unit 62 is compatible with 3GPP® standards such as UMTS, LTE, or NR and operates as appropriate depending on the current connection. In the embodiment, a controller 63, such as a microprocessor, is included to control the communication unit and its receiver 621 and transmitter 622. Note that the controller 63 is dedicated to the communication unit 62 and, in some cases, is included within it. The controller 63 further operates other systems and is not solely dedicated to the communication unit 62. Typically, some or all of the processes involved are operated by software stored in the memory 64 of the wireless terminal 410. However, it is also possible that the entire invention is included in the hardware within the components. Note that the wireless terminal includes functions for operating according to relay architectures such as sidelinks as defined in 3GPP® networks.

[0094] In this embodiment, the controller 63 causes the communication unit to operate in TX-restricted mode (i.e., a mode in which the wireless terminal cannot (or does not want to) transmit directly to the cell station, and the wireless terminal has reduced its transmit power but can still receive downlink signals from the cell station). This can be implemented according to an architecture as described with reference to Figure 4, or in any of the further embodiments further detailed herein. The controller 63 has the capability to configure the receiver and transmitter of the communication unit and to generate uplink data (e.g., user data, acknowledgment data, buffer status information). Depending on the conditions currently encountered, or based on a specific trigger message, the controller 63 switches to TX-restricted operation mode.

[0095] In TX-restricted mode, the receiver is adapted to receive a first downlink signal sent directly by a first cell station carrying each first downlink control information, one of which includes configuration parameters (such as a first resource instruction, a transmit mode instruction, or an operating mode instruction, or one or more other parameters relating to communication (receive or transmit)) to be used by the wireless terminal to transmit a second signal (i.e., an upstream signal / message) to a relay station, and at least one of which includes a second allocated downlink resource to be used by the wireless terminal to receive further downlink signals directly from the first cell station. Configuration parameters include, for example, resources, frequency, time / wake-up schedule, information on which modulation or signal encoding or scrambling or transmit power should be used for upstream signals / messages, information on which specific types of upstream signals / messages should be used (such as sidelink discovery messages), and / or L1 / L2 source or target identity information (or other identity information such as user information ID, PRUK ID, SUCI, SUPI, GUTI, or RNTI) (e.g., relay station identity) to be used in upstream signals / messages, or a specific set of security certificates to be used for upstream signals / messages. The receiver is further adapted to receive additional downlink signals directly from the first cell station on the second allocated downlink resource. Optionally, resource acquisition messages and data transmissions occur within the same radio frame.

[0096] In TX-restricted mode, the transmitter is adapted to transmit a second signal (i.e., an upstream signal / message (such as in step S54 above)) carrying uplink information to a relay station on a first resource, and / or uses the received configuration parameters to generate an upstream signal / message having desired characteristics (e.g., specific transmit power based on battery level, frequency, modulation format, coding scheme, protection mechanism), and the uplink information is then forwarded to a second cell station (e.g., by forwarding the received upstream signal / message and / or by sending a different message containing the uplink information).

[0097] As an option in this embodiment (and applicable to other embodiments), the controller initiates TX limit mode operation after the receiver receives a downlink signal directly transmitted by the first cell station (for example, after the first cell station determines through measurement that the uplink signal of the wireless terminal is of poor quality), by instructing or including a trigger to activate TX limit mode. As previously mentioned, this triggers a reduction in the transmit power or various resources to be used (for example, upstream resources directed towards the relay station rather than uplink resources for direct Uu communication with the first cell station). For this purpose, the cell station transmits a separate TX-restricted-mode switch message or TX-restricted-mode information element as a downlink signal, or as a specific downlink signal (e.g., having a specific waveform or frequency) for this purpose, as part of, for example, an SIB or RRC message or awakening signal (i.e., a unique signal received by an awakening receiver to awaken the main radio communication module, such as a WUS-like signal as specified in 3GPP® TS36.300 and TS36.213, or a IEEE 802.11ba-like signal; thus, the trigger for switching to TX-restricted-mode is indicated by the specific timing / resource / identity used or through the awakening signal payload). Such a message / information element / signal includes the identity of the wireless terminal (e.g., L2 identity, SUCI / SUPI / GUTI, or RNTI) or the identity of the group of devices to which the wireless terminal belongs (e.g., L2 group identity), so that the wireless terminal can determine that the message / information element / signal applies to its respective wireless terminal.The aforementioned messages / information elements / signals must be encrypted (for example, using a pre-shared or public key received from a first cell station (signed by the core network or a certificate authority), or using a previously used key or a key derived from this key (for example, based on Kamf, Kausf, or ProSe remote user keys (PRUK))) in order to prevent a malicious device from using such messages to force a wireless terminal to switch to TX-restricted communication.

[0098] As an alternative (to this embodiment and other embodiments), the controller initiates TX limit mode operation if a transmit or receive operation satisfies one or more (pre-configured) conditions (e.g., configured by the cell station through SIB / RRC messages or UE policy information (e.g., from PCF), or pre-configured in the USIM), or a (pre-configured) signal strength / signal reception quality threshold or signal transmission failure threshold, or if the energy level of the wireless terminal falls below a certain threshold. This decision is based, for example, on one or more of the following methods: a) A measurement of the signal metric of a signal received directly by a wireless terminal from the first station of a cell, a signal received by the wireless terminal from a relay station, or a signal received by the wireless terminal from another cell station. For example, an event such as the RSRP of a downlink transmission from a cell station falling below a certain threshold indicates to the wireless station that the wireless terminal is approaching the edge of a coverage area from which it can transmit directly to the cell station. The wireless station may need to take measurements at specific time intervals or apply some historical offsets to ensure that the situation is stable and to avoid the ping-pong effect. The threshold to be applied here is (pre) configured by the cell station through configuration information sent to the wireless terminal (e.g., as part of the SIB), which includes conditions / policies (e.g., RSRP thresholds) that the wireless terminal should apply to decide to use TX limiting mode. b) Detection of failed or nearly failed transmissions, such as retry counters reported directly from the wireless terminal to the cell station or vice versa, or retry counters reported to the wireless terminal via a relay station, where there is no acknowledgment of the message sent to the first cell station. The threshold to be applied here is (pre) configured by the cell station through configuration information sent to the wireless terminal (e.g., as part of the SIB), which includes conditions / policies that the wireless terminal should apply to decide to use TX limiting mode (e.g., the maximum number of failed uplink transmissions). c) Coverage expansion mode requested by a possible wireless device or enabled by the network. d) Whether the remaining battery charge or battery / power type used by the wireless terminal, and / or the Tx power level of the wireless terminal are above / below a specific threshold.

[0099] Alternatively, the controller may initiate TX-restricted mode operation when a relay station is discovered, and therefore, discovery messages received from the relay station may indicate support for TX-restricted operation or specify a field (e.g., a Boolean element) that should trigger a wireless terminal to switch to TX-restricted mode when it is included or has a certain value.

[0100] As yet another option (in this embodiment and other embodiments), the transmitter is adapted to transmit an initial signal that instructs or includes a trigger to activate TX-restricted mode, either directly to the first cell station (i.e., via the Uu interface) or to a relay station (i.e., via an indirect message to be forwarded to the first cell station by the relay station, for example, using the ProSe relay procedure). In the case of the Uu interface, this is a one-time high-power "hello" message transmission sent directly to the first cell station as a new or existing RACH message (with new / additional informational elements instructing a request for TX-restricted mode) sent over an unscheduled resource, for example, via an allocated UL resource or during a random access procedure (see TS38.300), assuming that the wireless terminal still has sufficient Tx power reserves and energy remaining to send a "hello" message transmission. In this way, the wireless station can notify the cell station that the wireless terminal is there and that the wireless terminal requires a relay station to send a reply (at a sustainable lower power transmission level). As soon as a cell station receives such a message, it determines, for example, which relay station the wireless terminal should use (if the wireless terminal is not already using it), based on location information, measurement data, or discovery information further included as part of such an initial signal (e.g., a "hello" message), schedules an upstream resource for the wireless terminal as appropriate, and then transmits this upstream resource to the wireless terminal in one of the first downlink signals mentioned earlier.

[0101] As another option, when a wireless terminal stops using TX restricted communication mode, the relay station may optionally continue listening for upstream signals from pre-authorized wireless terminals that exist within a pre-established security context. This is useful for detecting, for example, devices that can only use TX restricted communication at this time (and therefore do not have the ability to reach the cell station directly), devices that have entered the vicinity of the relay station, and devices that need to communicate. For this purpose, pre-authorized wireless terminals must use a unique identity or certificate in their discovery, relay join request, or other upstream signals / messages (e.g., PC5 signaling messages). To enable the relay station to verify that the wireless terminal is pre-authorized, the relay station may configure the corresponding information or remember the corresponding information from previous communications with the wireless terminal (e.g., using the same or induced PC5 session key). Alternatively, the relay station may forward incoming upstream signals to the cell station to which it is connected and / or to the core network for further processing and to further check whether the wireless terminal is pre-authorized.

[0102] In the case of TX-restricted mode, the wireless terminal sends uplink information to a relay station rather than directly to the cell station. Therefore, the wireless terminal deploys two sets of antennas (e.g., an antenna for receiving DL signals from the cell station coming from one direction, and an antenna for transmitting upstream signals to the relay station in the other direction), or a single set of antennas that intermittently switches between a mode for receiving DL signals from the cell station and a mode for transmitting upstream signals to the relay station. For this purpose, the wireless terminal is configured by the cell station with (estimated) location information (e.g., geographic or relative coordinates, or distance / direction from a reference point) and / or directional information (e.g., the angle between the DL signal coming from the cell station and the upstream signal going out to the relay station, the transmission angle relative to the reference line or magnetic north of the DL signal or upstream signal). This allows the wireless terminal to configure its antennas appropriately and receive signals from the correct direction / transmit signals in the correct direction (e.g., by changing the beamforming characteristics of the transmitted signal). This allows beamforming towards the relay station (either a different beam or having a different synchronous signal block (SSB) index than the beam directed towards the first cell station). The wireless terminal is further configured by the cell station with information about the timing of mode switching (e.g., based on normal intervals or for resources scheduled for downlink and upstream communications). This is useful in cases where the antenna switches between a mode for receiving DL signals from the cell station and a mode for transmitting upstream signals to the relay station. Alternatively, the wireless terminal deploys one or more omnidirectional antennas, in which case location / angle is not required and is ignored. However, in the case of a single omnidirectional antenna, mode switching is applied, and the wireless terminal is appropriately configured with information about the timing of mode switching.

[0103] In other words, optionally, the receiver and transmitter operate different sets of antennas, and the controller instructs the transmitter to perform beamforming toward the relay station based on, for example, the relay station's location and / or angular information (e.g., the angle between the beam used for downlink signals from the cell station, such as those received by wireless terminals, and the beam used for upstream signals directed toward the relay station). Such location or angular information is received from the first cell station and / or relay station.

[0104] In this embodiment, the controller 63 alternately operates the communication units according to a network having a conventional architecture and a network having a special architecture as described with reference to Figure 4 or in any of the further embodiments described below. Depending on the conditions currently encountered or based on a specific trigger message, the controller 63 switches from conventional operation (e.g., direct bidirectional operation by a cell station acting as a scheduler) to asymmetric operation (i.e., TX-limited operation mode). In this case, the controller 63 can configure the receiver to receive and decode resource-reservation messages indicating downlink messages (e.g., paging messages) coming from the cell station, and to receive downlink data transmissions from the cell station on the scheduled radio resources. Optionally, the resource-reservation message and data transmission occur within the same radio frame.

[0105] Furthermore, the controller 63 is adapted to request radio resources for data transmission by causing the transmitter 622 to send a message to at least one relay station 420.

[0106] Furthermore, as explained in relation to the flowchart in Figure 5, the reserved message coding, content, and / or timing can optionally instruct the wireless terminal 410 to allocate Ds resources for receiving downlink data and Us resources for transmitting data, within a single message.

[0107] The transmitter 622 can be configured to send data intended for a cell station to a relay station via reserved upstream resources. The data included may include, for example, feedback data such as ACK / NACK indicating whether the wireless terminal 410 has successfully received data transmission from the cell station, new user data destined to go to an edge server located on the network or at the first cell station, or other control messages such as buffer status report (BSR) data indicating the status of one or more of the transmit buffers of the wireless terminal 410.

[0108] As shown in Figure 7, a relay station 420 capable of operating as a relay UE typically includes an antenna 71 or antenna array (for example, in the case of a MIMO-compatible wireless terminal). This antenna 71 is coupled to a communication unit 72 comprising a receiver 721 and a transmitter 722. In these exemplary embodiments, the communication unit 72 is compatible with 3GPP® standards such as UMTS, LTE, or NR and operates as appropriate depending on the current connection. Embodiments include a controller 73, such as a microprocessor, for controlling the communication unit 72 and its receiver 721 and transmitter 722. Note that the controller 73 is dedicated to the communication unit 72 and, in some cases, is included within it. The controller 73 is not solely dedicated to the communication unit 72, but also drives other systems. Typically, some or all of the processes involved are operated by software stored in the memory 74 of the relay station 420. However, it is also possible that the entire invention is contained within the hardware of the components. Please note that relay stations, as relay UEs in 3GPP® networks, include functions to operate in accordance with relay operations such as sidelink transmission and reception.

[0109] In this embodiment, the relay station is directly or indirectly connected to a network, such as a core network (CN), via a cell station, such as a RAN base station. The receiver 721 is configured by the controller 73 to receive and decode an upstream allocation sent by the cell station, which indicates the resources to be used for upstream transmissions coming from the wireless terminal 410. This scheduling allocation includes allocation coding, content, frequency information, and / or timing information, implicitly or explicitly indicating (e.g., by an identifier) ​​the resource to be reserved for use by the wireless terminal 410, which is directly connected to the relay station via a radio link. Optionally, an identifier of the wireless terminal 410 (e.g., an L1 or L2 identifier) ​​is included in the scheduling allocation to indicate the wireless terminal 410. The controller 73 is adapted to configure the receiver to subsequently receive data from the wireless terminal 410 on the scheduled resources, as mentioned in step S55.

[0110] The controller 73 is adapted to control the receiver 721 and transmitter 722 in order to relay upstream data from the wireless terminal 410 to the cell station 400 according to relay operation. This forwarding transmission is either direct or indirect through the upstream parent node.

[0111] Furthermore, the relay station is adapted to send feedback data (e.g., ACK / NACK) to the wireless terminal 410 in response to receiving data from the wireless terminal 410, indicating whether or not the data was received correctly.

[0112] As shown in Figure 8, the cell station 400 includes an antenna 81 or an antenna array (for example, in the case of a MIMO-compatible cell station). This antenna is coupled to a communication unit 82, which includes a receiver 821 and a transmitter 822. In these exemplary embodiments, the communication unit 82 is compatible with 3GPP® standards such as UMTS, LTE, or NR and operates as appropriate depending on the current connection. Embodiments include a controller 83, such as a microprocessor, for controlling the communication unit 82 and its receiver 821 and transmitter 822. Note that the controller 83 is dedicated to the communication unit 82 and, in some cases, is included within it. The controller 83 is not only dedicated to the communication unit 82 but also drives other systems further. Typically, some or all of the processes involved are operated by software stored in the cell station 400's memory 84. However, it is also possible that the entire invention is included in the hardware within the components. Furthermore, the cell station 400 includes a scheduler 85 coupled to the controller 83, which is responsible for allocating the cell's shared resources to multiple secondary stations. Interface 86 is included for managing communication with the core network. Interface 86 can be further adapted to manage communication with other cell stations via different interfaces (e.g., X2) using backhaul channels.

[0113] As illustrated with respect to Figure 5, the controller 83 of cell station 400 is adapted to configure transmitter 822 to transmit downlink data to wireless terminal 410. The controller can operate without receiving any transmissions, such as feedback from the wireless terminal 410 (at least not directly). Furthermore, receiver 821 is adapted to receive and process feedback data indicating whether previous DL transmission data to wireless terminal 410 was successfully received, and the feedback data is received from wireless terminal 410 directly or indirectly, i.e., via relay station 420.

[0114] Furthermore, the scheduler is adapted to schedule resources to enable the special asymmetric operation shown in Figure 5. This includes scheduling downlink data for direct downlink transmissions from cell station 400 to wireless terminal 410. This further includes allocating upstream resources between wireless terminal 410 and relay station 420. The corresponding resources (for receiving upstream signals / uplink information from wireless terminal 410) are further signaled to the relay station to direct incoming upstream transmissions from the wireless terminal. Finally, in this particular example where the relay station is located within a cell served by the cell station, the scheduler can further schedule resources to be used by the relay station for forwarding incoming upstream data.

[0115] The scheduling operation is at least partially based on information regarding the buffer status of various stations in the network, including the relay station 420 and possibly the wireless terminal 410. The BSR can be received directly or indirectly from the wireless terminal 410.

[0116] Similar to the wireless terminal 410 and the relay station 420, the controller 83 can switch for any given station between a “normal” operating mode (direct bidirectional connection), a “relay” mode (indirect bidirectional connection (all upstream and downstream communications pass through one or more relay stations)), and / or a “TX-restricted” mode (indirect connection with direct DL data transfer and scheduling). This connection mode is selected depending on the capabilities of the given UE, i.e., if the UE supports these modes.

[0117] As a result of this embodiment, a wireless terminal acting as a remote UE can reduce the number of times it needs to "detect" sidelink channels to self-schedule resources to transmit—in many cases, the wireless terminal can simply wait for the cell station's (gNB) scheduling decision on Us resources and transmit over those Us resources. This thus reduces the energy consumption of the wireless terminal.

[0118] Furthermore, a cell station or gNB can more optimally schedule communication resources using knowledge / data / measurement reports from many UEs, as well as knowledge / data / measurement reports from even more communication resources / channels / bandwidth. Thus, a cell station or gNB has the ability to better evaluate the load per relay station and more intelligently decide on the scheduling and / or switching of possible UEs to this asymmetric operating mode.

[0119] It should be noted that in some situations, for example, when a cell station has not allocated any resources to a wireless terminal, and the latter needs to indirectly indicate to the network that it has data waiting to be transmitted, for example, by transmitting a BSR and / or by transmitting user data to a relay station (e.g., urgent user data such as for emergency services), self-scheduling by the wireless terminal is still necessary.

[0120] Furthermore, in "TX-restricted" mode, data can be sent directly from the cell station to the wireless terminal acting as a remote UE without requiring an indirect route through a relay station, as is typically the case with relay data, resulting in a larger downlink data capacity, similar to "relay" mode. As a result, data from the cell station to the wireless terminal does not "burden" the sidelink (SL) resources available between the relay station and that wireless terminal. In one implementation where the network or relay station defines how sidelink resources are shared between upstream and downstream data, it is possible, for example, to reduce the sharing of downstream sidelink resources for the sake of upstream sidelink resources. This makes more sidelink resources available for other types of sidelink communication (e.g., D2D, V2X, ProSe, relay).

[0121] In the case of a relay station, another advantage is that it does not need to detect all potential SL channels that a wireless terminal acting as a remote UE might transmit on 24 / 7. Instead, the relay station specifically listens on a scheduled channel, i.e., resource Us-Rx, to receive wireless terminal transmissions. As a result, the relay station can use more advanced "energy-saving" modes, such as those in 3GPP® (e.g., DRX energy-saving mode), which do not require the relay station to "always on" listening on sidelink resources that wireless terminals might potentially send data to the relay station.

[0122] Some further details regarding resource scheduling as envisioned for 5G are provided below. 5G resource scheduling consists of a complex interaction of multiple scheduling mechanisms and protocols that work together.

[0123] The primary scheduling method in 5G is dynamic, meaning resources are allocated according to demand based on available data and channel conditions. There is also semi-persistent scheduling (SPS), which is a pre-configured schedule that can be quickly activated / deactivated by the gNB based on current demand. Finally, there is persistent scheduling, which can only be activated once and remains active until explicitly cleared by a specific designated event. The intention is that dynamic scheduling decisions are always added in addition to persistent / semi-persistent scheduling decisions to handle special events such as fluctuations in data rates or data retransmissions. A complex ensemble of reporting structures for reporting measurements to the gNB, along with control mechanisms for the gNB to enable / disable / request reporting on the fly, for the scheduler to learn channel conditions, is defined in 3GPP®.

[0124] Various protocols are used when implementing scheduling mechanisms. ● See also RRC, Figure 2B. This can operate end-to-end between the gNB and UE in the UL and DL, potentially via one or more relay hops on the SL when using the new L2 relay architecture. RRC is primarily used for non-time-critical static or semi-static scheduling information. In other words, it is the scheduling configuration. ConfiguredGrantConfig is the information element for uplink scheduling. ● MAC Control Elements (CEs) - These are short elements (also known as information elements, or IEs) inserted between existing UL / DL / SL transmissions via the MAC layer, used to efficiently signal specific events or configurations in UL, DL, or SL. One specific case is the Buffer Status Report (BSR) MAC CE used by the UE to signal the UE's current data buffer status to the gNB / scheduler. The MAC CE is the primary mechanism for the UE to indicate that it has data pending that requires UL scheduling. When the UE has some data available for transmission in its buffer, and UL acceptance for resources, the UE uses a portion of these resources to add information about one or more of its buffers for one or more corresponding logical channel groups. However, when there is no UL acceptance for a resource, another mechanism for requesting the resource is the Scheduling Request (SR) in the UCI. Other MAC CEs are used by the gNB to control the UE's behavior when performing the measurements and DRX described above. ● Downlink Control Information (DCI) - Short messages sent downlink on a low bitrate control channel (PDCCH) with special blindly detectable modulation / coding. This is at the PHY L1 layer and does not use the MAC L2 header structure. Various DCI formats with different information content are defined. Resources for dynamic scheduling are indicated in the DCI, and DL data transmissions typically follow the DCI message within 1 ms, but can be scheduled up to 4 ms ahead. For UL, scheduling is typically done for the next slot 1-2 ms ahead, but can be up to 8 ms ahead. For scheduling sidelink resources, DCI formats 3_0 and 3_1 are defined in TS38.212. These are only SL resources that should be used by the UE itself scheduled for transmission, and not SL resources used by remote UEs to transmit to relay UEs.

[0125] In this document, the term "downlink control information" is used as a general term for any control / configuration-related information and is not necessarily limited to DCI-related content / messages, but should be noted as it may also be sent as part of a System Information Block (SIB), RRC, or MAC CE message, for example. ● Uplink Control Information (UCI) - A short sequence of bytes sent over the uplink in PUCCH using one of several different formats. The UCI contains a Scheduling Request (SR) bit and is used by the UE when there are no UL resources to send a BSR MAC CE. In response to the SR, the gNB scheduler will allocate UL resources for the UE in the future.

[0126] Of the above, only RRC protocol messages can be carried end-to-end between the remote UE and the gNB in ​​the case of the L2 relay architecture (see Figure 3). All other mechanisms must function directly between the gNB and the UE, or, if defined, between the relay UE and its downstream remote UEs, when they are in direct radio contact at L1 / L2.

[0127] The resource scheduling overview described above is applicable to UEs directly connected to the gNB. When single or multi-hop relays are introduced into the network, these solutions are insufficient, as they primarily operate on direct links between the gNB and the UE. There are guidances for various solutions already known or discussed by the 3GPP® RAN Working Group on how such scheduling can function in single-hop relay scenarios. For example, these include: ● An OoC remote UE can self-schedule its transmissions on the SL based on its own channel measurement and random access process. This is referred to as "resource allocation mode 2" in TR37.985. ● The gNB can schedule resources for all directly connected relay UEs to send to remote UEs, as defined in TR37.985 "Resource Allocation Mode 1". However, there is no mechanism for the gNB to schedule resources for reverse traffic returning to the relay UEs. ● gNB schedules all resources for all directly and indirectly connected UEs (Note: Details of this method have not yet been defined by 3GPP®). ● One primary UE in a group can adjust resource allocation to match its group members, and in some cases, this may work even if some group members are outside coverage but still within the primary group member UE's scope.

[0128] One issue recently mentioned in discussions at the 3GPP® RAN#86 meeting regarding the scope of Release 17 is that it is important to note that self-scheduling for sidelinks (SLs) as currently defined for V2X communication is considered energy inefficient and therefore unsuitable for small battery-powered devices such as mobile phones or IoT devices. The primary V2X use case for this communication has so far been V2V (vehicle-to-vehicle) communication, where energy consumption is not a major concern.

[0129] In a variation of a previous embodiment, the wireless terminal can be connected as a remote UE. In this role, the wireless terminal can detect that it is capable of receiving signals from one or more cell stations. Once this is determined, the wireless terminal sends a message to its relay station (e.g., a relay UE) indicating the signals (and / or the identity of the cell stations) that the wireless terminal is capable of receiving. The message includes instructions regarding energy, power levels, and signal quality, which help in determining whether to switch to an asymmetric operating mode. The relay station then further sends or relays this information to its own upstream cell stations. Optionally, this information is further dispersed within the RAN so that the RAN can configure at least one cell station (preferably corresponding to the one first detected by the wireless terminal) for direct data transmission and / or resource allocation, as described in a previous embodiment or as detailed in a further embodiment.

[0130] Furthermore, when a wireless terminal is connected as a remote UE and in a TX-restricted state, the cell station can be configured to monitor and detect the change from the TX-restricted state to a normal state that enables bidirectional communication with the wireless terminal. This can be done, for example, by the cell station detecting a transmission from the wireless terminal to the relay station made on an allocated Us resource. Other suitable methods (monitoring RSSI, signal quality monitoring based on a reference signal, or others) may be used. Accordingly, the cell station notifies the wireless terminal that it is triggering a switch from TX-restricted operation to normal operation.

[0131] When a wireless terminal is connected as a remote UE in a TX-limited state, the wireless terminal also detects a change from the TX-limited state to a state outside of gNB coverage where further communication with the gNB is not possible. This can be monitored by detecting that no more gNB transmissions are being received, such as a synchronization signal or periodically broadcast system information (SIB). Alternatively, conventional monitoring of some received power or quality (similar to measurements performed for handover) is used in this context. In response, the wireless terminal switches from TX-limited operation to normal relay operation, such as a remote UE. The wireless terminal further notifies the cell station gNB of this new situation (via indirect messages forwarded by the relay UE).

[0132] In this embodiment, suppose we select the case where wireless terminal 410 is connected as a remote UE and in a transmit-limited state. When relay station 420 detects that wireless terminal 410 has gone out of coverage of cell station 400 and therefore relay communication with the cell station is no longer possible, relay station 420 stops its relay operation for wireless terminal 410 and notifies wireless terminal 410 via a sidelink message. Wireless terminal 410 then begins a discovery process to find a new relay station to use. Meanwhile, wireless terminal 410 also checks whether it is possible to re-enter normal operation through direct bidirectional operation with the cell station. For relay station 420 to detect that wireless terminal 410 has gone out of coverage, wireless terminal 410 can detect that no more gNB transmissions are being received, such as periodically broadcast system information (SIB). In another example, the relay station can use one of the measurement events, such as detecting that the RSRP / RSRQ from the cell station is below a threshold. These events are signs that the relay station is moving outside the cell or that its connection quality is deteriorating. Another possibility is that the relay station is notifying of a substantial change in location, for example, based on GPS coordinates.

[0133] In a further embodiment, a cell station (designated gNBx) sends out a specific “discover” type signal instructing all wireless terminals that are acting as remote UEs and / or in a transmit-restricted state, and so that wireless terminals should respond to the signal if they are capable of receiving it. After receiving such a signal, such wireless terminals operating in full relay operation can respond by sending a discovery request or response (e.g., using a ProSe / sidelink discovery message) to their own relay station 420 or another nearby relay station 420. Relay station 420 then forwards the discovery response via the RAN to its own cell station gNB1 that generated the “discover” signal, to the core network CN, and / or cell station gNBx, if this is part of its active set (base stations that relay station 420 is currently in contact with). After receiving the discovery response, one entity in the RAN (e.g., gNBx) configures a direct transmission of data / resources to a possible wireless terminal, as described in embodiments of the present invention (e.g., to enable asymmetric operation modes).

[0134] In these various examples, a cell station gNBx can determine that a possible wireless terminal is in a TX-restricted state, and / or the network (e.g., NG-RAN) can determine that a possible wireless terminal is in a TX-restricted state and then instruct one or more cell stations to use the TX-restricted operation by the possible wireless terminal. This determination can be based on one or more of the following methods: a) Measured signal metrics of signals received directly by a cell station from a possible wireless terminal, signals from a wireless terminal received by a relay station, signals from a relay station near the wireless terminal, signals from a relay station serving the wireless terminal, or signals from a wireless terminal received by another cell station. For example, an event in which the RSRP of an uplink transmission from a wireless terminal falls below a certain threshold indicates to the cell station that the wireless terminal is approaching the edge of the coverage area from which it can transmit directly to the cell station. The cell station may need to take measurements over a specific time interval or apply some historical offset to ensure that the situation is stable and to avoid the ping-pong effect. b) For example, detection of a failed or nearly failed transmission, such as a message sent to a wireless terminal not being acknowledged, a retry counter reported directly from the wireless terminal to the cell station, or a retry counter reported from the wireless terminal to the cell station via a relay station, or the wireless terminal's Tx power level subsequently reported directly to the cell station exceeding a certain threshold. c) Coverage expansion mode is requested by a possible wireless terminal or enabled by the network. d) Historical or analytical data indicates that the wireless terminal is experiencing an uplink problem. e) Capability information and / or status information of a possible wireless terminal (e.g., representing TX limiting capability and / or status), and / or identity information (e.g., a device belonging to a specific group of TX limiting devices), received from a possible wireless terminal, from an application function, or from an Integrated Data Management (UDM) network function (e.g., part of subscription information), or received through a Network Exposure Function (NEF), (e.g., through RRC, MAC CE, or an initial RACH message or registration / installation message). This includes knowledge of the device model, number of antennas, UE category, and whether it supports RF backscatter communication. f) The remaining battery charge, or the type of battery / power source used by the wireless terminal. This further includes information on whether the device has no battery and / or is obtaining energy solely from energy harvesting. This information is reported, for example, while the wireless terminal still has a bidirectional link with the cell station, or through the initial RACH message or registration / installation message.

[0135] In a further variation of the previous embodiment, for example, based on one of the mechanisms discussed above, as soon as the cell station determines that a possible wireless terminal is in a TX-restricted state, the cell station sends a message to a relay station (preferably the relay station communicating with the possible wireless terminal) indicating, possibly, the identity of the wireless terminal and indicating that the wireless terminal should use a TX-restricted communication mode. The indicated identity of the possible wireless terminal is used in future resource scheduling messages from the cell station, and the relay station can therefore infer from the resource scheduling messages that the wireless terminal intends to send upstream data to the relay station. The relay station may also be informed of incoming uplink messages on part of the uplink / upstream resources. As an example, the identity is the RNTI (Radio Network Temporary Identifier) ​​of the wireless terminal. The relay station uses this RNTI in addition to its own RNTI to monitor PDCCH messages to receive DCI from the cell station for the wireless terminal and to use the DCI to receive upstream information from the wireless terminal using the allocated uplink / upstream resources.

[0136] Alternatively, a cell station signals a set of Us-Rx resources (e.g., a resource pool) to be monitored by a relay station (instead of a specific resource for a single transmit). The actual resources allocated to a wireless terminal are simply one or more resource blocks from the set of Us-Rx resources signaled to the relay station by the cell station. As in the example above, the identity of one or more wireless terminals expected to transmit is optionally signaled. The set of Us-Rx resources can be further signaled as a semi-persistent schedule, a time / wake-up schedule, or as a specific frequency to be monitored.

[0137] In a further variation of the present invention, the wireless terminal can connect to a relay station using the 3GPP® 5G ProSe relay discovery and selection procedure.

[0138] In yet another variation of the previous embodiment, the wireless terminal can indirectly (via a relay station) report any location changes to the cell station in a location change status report. If there is little to no location change, the cell station can maintain the same operating mode for the wireless terminal (e.g., full relay operation or TX-restricted mode, or direct bidirectional mode). If there is a significant location change, the cell station can adapt its transmission settings toward the wireless terminal and / or have a different cell station take over its role as a direct cell station. Another possibility is that the cell station configures the wireless terminal to initiate or perform some measurements to detect if another cell station is more appropriate or if a different operating mode is more suitable for the current conditions. The measurements performed by the wireless terminal can be similar to those performed for the cell station handover mechanism.

[0139] In yet another variation of the previous embodiment, a cell station can configure and activate intermittent reception (DRX) mode in a wireless terminal via direct message, and the wireless terminal can then transmit to its relay station during its “awakening” time. The DRX mode reduces the terminal’s energy consumption by intermittently switching off its communication unit and allows it to be activated during a certain periodic awakening cycle. Since the cell station is aware of the periodicity of the DRX burst pattern, it can appropriately adjust resource scheduling. Similarly, the cell station can activate DRX in a relay station and then schedule resources for transmission from the wireless terminal to its relay station only during the awakening cycles of both the wireless terminal and the relay station.

[0140] It should be noted that all previously described embodiments may be combined with one another. Furthermore, unless expressly indicated otherwise, these modifications are equally applicable to other embodiments of the present invention.

[0141] According to a second embodiment of the present invention, the operation of the system will now be described with reference to Figure 9. In this system, the wireless terminal 910 is within the coverage of cell station 900, i.e., cell 90. A relay station 920, further connected to cell station 900, can function as a relay between the wireless terminal 910 and cell station 900. During normal operation, the wireless terminal can directly receive data and control signaling from cell station 900 and directly transmit data and control information back to the cell station over the link. If the wireless terminal 910 is completely disconnected from cell station 900, for example, if it is unable to properly receive signals originating from cell station 900, the wireless terminal 910 can enter full relay operation thanks to the relay station 920. In this mode of operation, all upstream and downstream connections pass through the relay station 920. However, as described in previous embodiments, the wireless terminal 910 can further operate in TX-restricted operation when it is in a TX-restricted state.

[0142] In this particular case, the wireless terminal 910 can generate upstream user data to be sent via the relay station 920. The data is then optionally authorized by the cell station 900 via direct transmission. The detailed operation is carried out as described below. ● As the first step S90 (not shown), optionally, the wireless terminal 910 instructs the relay station 920 that it has pending data to transmit. This can be done, for example, by using a pre-configured sidelink resource for this purpose, for example, through a Buffer Status Report (BSR) type message, or a scheduling request type message followed by a BSR. This step is optional, especially if the cell station already has a scheduled Us resource for the wireless terminal 910 and a corresponding resource Us-Rx for the relay station 920, for use in the near future (for receiving incoming upstream data), based on a BSR or SR+BSR previously received by the cell station, for example. After the wireless terminal 910 sends this instruction to the relay station 920, for example, a Buffer Status Report type message, the relay station 920 instructs the cell station that the wireless terminal requires the resource. This can be done simply by forwarding the corresponding BSR, or by some other signaling. The wireless terminal sends additional information to the relay station, for example, a measurement report or other message indicating that the wireless terminal 910 is currently a TX-restricted station, i.e., it can directly receive data from the cell station 900 but cannot successfully send data to the cell station 900. The wireless terminal sends a further request to transition to TX-restricted operation (for example, due to limited remaining battery capacity or other events, as mentioned in the previous example). In addition, some user data with SR / BSR and the previously mentioned message inserted is sent to the relay station 920. When the cell station 900 receives information via the relay station that the wireless terminal 910 needs resources or is operating / supporting TX-restricted mode, the cell station 900 schedules upstream resources for the wireless terminal 910 and further schedules corresponding resources for the relay station 920 to receive the upstream signal from the wireless terminal 910 and send the scheduled resources as part of the first or second downlink signal.Alternatively, even if the wireless terminal 910 is TX-limited, the wireless terminal 910 may send a specific signal (e.g., a narrowband pulse, or a scheduling request, or a signal at a specific frequency and / or a frequency lower than the frequency the wireless terminal normally uses for operation, or a signal temporarily sent at a transmit power higher than the transmit power that the device can sustain for a longer period) that can be received by the cell station 900 (or another nearby cell station) and indicate that the wireless terminal needs resources or should operate / support TX-limited mode. If such a signal is received by the cell station 900, the cell station 900 will schedule upstream resources for the wireless terminal 910 and further schedule corresponding resources for the relay station 920 to receive the upstream signal from the wireless terminal 910 and to send the scheduled resources as part of a first or second downlink signal. ● In step S91, cell station 900 (gNB1) transmits a single control message containing resource allocation, or a set of control messages instructing a set of resource, frequency, and / or time / wake-up schedule related information. This control message includes an identifier for wireless terminal 910, or a common identifier in the concatenation "wireless terminal 910-relay station 920". This message instructs a Us resource, or a specific frequency for use by the wireless terminal to perform future data transmissions, and / or a corresponding instruction for resource allocation (for use by the relay station) that directs incoming upstream data from wireless terminal 910 corresponding to the Us resource. In the example, the instructions for the allocated Us resource and allocated Us-Rx resource for incoming upstream are represented in a single field or in a single byte array in the control message. As another example of instructions regarding allocated Us resources, a control message from cell station 900 (gNB1) includes flags or parameters to instruct wireless terminal 910 to use a subset of sidelink resources already configured on wireless terminal 910. The control message further includes additional information on how the upstream signal should be transmitted by wireless terminal 910 (e.g., what modulation or signal encoding or scrambling or transmit power should be used, what particular type of signal / message (e.g., a sidelink discovery message) should be used / generated), and / or what L1 / L2 source or target identity information (or other identity information such as user information ID, PRUK ID, SUCI, SUPI, GUTI, or RNTI) should be used in the message (e.g., the identity of the relay station), or what particular security certificate should be used for the message. Wireless terminal 910 uses this information to generate each upstream signal to be received by relay station 920.Similarly, the relay station 920 receives corresponding information from the cell station 900 and uses this information to receive a specific upstream signal from the wireless terminal 910.

[0143] It should be noted that the wireless terminal 910 and the relay station 920 are pre-configured to monitor the control area based on the corresponding DCI type and identifier. As previously mentioned, the identifier can be a newly defined “remote-UE-RNTI” associated with the wireless terminal 910, or an identifier created for the “wireless terminal 910-relay station 920” concatenation. This allows each relay station to schedule resources for different wireless terminals, which reduces the risk to the relay station of completely disrupting the upstream connection of the wireless terminals if the relay station leaves, as a backup relay station can be easily used by allocating different resources to the RNTI. When monitoring the control area, each of the wireless terminal 910 and the relay station then blindly decodes a set of PDCCH candidates based on the RNTI to detect whether a valid DCI is included.

[0144] Therefore, in step S91, both the wireless terminal 910 and the relay station 920 receive and decode the PDCCH message from the cell station 900, which has a CRC scrambled with this new RNTI type. As a result, this prompts the relay station 920 to attempt "reverse scrambling" of the PDCCH message with both its own identity (typically its C-RNTI) and the new RNTI in order to determine what and to whom the message is intended. If the PDCCH decoding is successful, the corresponding DCI enables the following configuration: - Wireless terminal 910 transmitter for preparing and transmitting data using allocated Us resources, and - A relay station 920 receiver (Rx) to listen for data transmissions using the same Us resource. ● In step S92, the wireless terminal 910 transmits data within the scheduled resource, and the relay station 920 listens for transmitted data within the same / corresponding resource. Typically, the cell station 900 is unable to properly receive the transmitted data due to transmission restrictions to the wireless terminal, as previously indicated. ● In step S93, relay station 920 relays the received data from the wireless terminal upstream to cell station 900. Note that this relay can be connected directly or indirectly via multiple hops. For simplicity, only direct relay is shown in Figure 9. Relay station 920 uses the uplink resources allocated in conjunction with the resources allocated in step S91 in a separate PDCCH message, and the CRC is now scrambled at relay station 920's RNTI. Semi-persistent scheduling resources may also be allocated to the relay station to enable it to forward data transmissions from all of its sidelink-connected terminals. Yet another possibility is that the message sent in step S91 includes a further allocation of resources to be used by the relay station for forwarding. This further resource allocation needs to be signaled before the normal allocation so that the relay station can process the incoming upstream and prepare the data packets to be forwarded. ● In step S94, cell station 900 optionally sends feedback data directly to wireless terminal 910 to acknowledge (ACK / NACK) the receipt of upstream data from relay station 920. This includes HARQ acknowledgment data, PDCP feedback data (or higher layer (e.g., IP), or others) using a PDCP control PDU, PDCP status report PDU type, and FMC and bitmap data as specified by TS38.323. Furthermore, cell station 900 may also (or alternatively) transmit this feedback data to wireless terminal (and thus indirectly) through a relay station. However, direct transmission is assumed to be more efficient. The feedback data is optionally combined with further downlink data to wireless terminal within the same transport block for efficiency.

[0145] Note that each transmission hop in an indirect network connection includes, for example, a corresponding MAC HARQ process to ensure that each hop is authorized at the MAC level.

[0146] The third embodiment depicted in Figure 10 corresponds to the second embodiment, except that the relay station 1020 is currently served by cell station 1001 (in cell 10b), which is different from cell station 1000 that serves the wireless terminal 1010 (in cell 10a). Thus, this particular case in which the wireless terminal 1010 generates upstream user data approved by cell station 1001 is described hereby. As described, there are two cell stations: cell station 1001, which is used by the relay station 1020, and cell station 1000, which is a cell station that can transmit directly to the wireless terminal 1010. Thus, cell station 1000 can transmit upstream resource allocations to the wireless terminal 1010, and cell station 1001 can transmit the corresponding upstream resource allocations to the relay station 1020. ● As a preliminary step not shown, the wireless terminal 1010 initiates / triggers resource allocation if necessary, as performed in step S90 of a previous embodiment. ● In step S100, the two cell stations 1000 and 1001 coordinate their next transmissions in time, providing a Us resource for use in transmitting for the wireless terminal 1010 and a Us-Rx resource for listening for the relay station 1020. In this case, the Us resource is either identical to or significantly overlaps with the Us-Rx resource (i.e., the Us resource is included in a signaled Us-Rx resource that can be signaled, for example, through semi-persistent scheduling (SPS), dynamic scheduling, or as a pool of resources). ● In steps S101 and S102, cell stations 1000 and 1001 each transmit communication resource reservation messages indicating wireless Us resources and Us-Rx resources, respectively, for use by one or more of the wireless terminals 1010 for future data transmission and by the relay station 1020 for data reception. Note that the Us-Rx resources are previously signaled, for example, as part of a relay configuration information element indicating a pool of resources or SPS allocation. In this case, this can be done before step S100. This is not specific to this embodiment and is further applicable to other described embodiments. Both the wireless terminals 1010 and the relay station 1020 receive the reservation via their respective cell stations and decode the PDCCH message by detecting or descrambling the message with an identifier, which is the “remote UE-RNTI” referred to in previous embodiments for both. Alternatively, this is a "remote UE-RNTI" to be used by the relay station to descramble PDCCH candidates, and a regular RNTI to be used by the wireless terminal to descramble PDCCH candidates. The relay station then configures its receiver (Rx) to listen for data transmissions using the Us-Rx resource.Alternatively or additionally, cell stations 1000 and 1001 exchange information with each other and / or transmit a set of control messages to wireless terminal 1010 that instruct on a set of resources, frequencies, and / or time / awakening schedule-related information, or additional information on how the upstream signal should be transmitted by wireless terminal 1010 (e.g., what modulation or signal encoding or scrambling or transmit power should be used, what particular type of signal / message (e.g., a sidelink discovery message) should be used / generated), and / or what L1 / L2 source or target identity information (or other identity information such as user information ID, PRUK ID, SUCI, SUPI, GUTI, or RNTI) should be used in the message (e.g., the identity of the relay station), or what particular security certificate should be used for the message. Wireless terminal 1010 uses this information to generate the respective upstream signals to be received by relay station 1020. Similarly, relay station 1020 receives corresponding information from cell station 1000 or 1001 and uses this information to receive a specific upstream signal from wireless terminal 1010. ● In step S103, the wireless terminal 1010 transmits upstream information within the scheduled Us resource, and the relay station 1020 receives upstream information within the Us-Rx resource.

[0147] Typically, cell station 1000 may be unable to properly receive transmitted data due to transmission restrictions to the wireless terminal, as previously indicated. Alternatively, cell station 1001 may be out of range for the wireless terminal, and / or wireless terminal 1010 may not have an active connection to cell station 1001 for direct transmission to cell station 1001. ● In step S104, the relay station 1020 relays the received upstream information from the wireless terminal 1010, such as user data, upstream to the cell station 1001. The cell station 1001 optionally notifies the cell station 1000 of which feedback data should be sent back from the cell station 1000 to the wireless terminal 1010.

[0148] It should be noted that this relay can be direct or indirect via multiple hops. For simplicity, only direct relay is shown in Figure 10. Relay station 1020 uses the uplink resources allocated in step S101 in a separate PDCCH message, this time with its CRC scrambled by relay station 1020's RNTI. Semi-persistent scheduling resources may also be allocated to the relay station, possibly even before step S100, to enable the relay station to forward data transmissions from all its sidelink-connected terminals. Another further possibility, as mentioned in previous embodiments, involves a further allocation of resources to be used by relay station 1020 for forwarding the message sent in step S101. This further resource allocation needs to be signaled earlier than the normal allocation so that relay station 1020 can process the incoming upstream and prepare the data packets to be forwarded. ● In step S105, the cell station 1000 optionally sends feedback to the wireless terminal, such as an acknowledgment indicating whether the data was received correctly, as in a previous embodiment. ○ These include HARQ or PDCP level approval as detailed in previous embodiments, or higher layers (e.g., IP), or others. The feedback data in steps 104 and 105 is marked as optional because, depending on the decision of the scheduler in cell station 1001, it is further sent to the wireless terminal 1010 via relay station 1020 instead of cell station 1000.

[0149] The fourth embodiment depicted in Figure 11 corresponds to the second embodiment, except that it represents a case where a wireless terminal receives downlink user data from the core network. As in the second embodiment, there may be only one cell station 1100 serving cell 11. ● In step S111, cell station 1100 transmits a communication resource allocation message, for example in PDCCH, which includes or indicates / encodes the identifier of wireless terminal 1110. This resource allocation message indicates the Us resources that wireless terminal 1110 can transmit over the sidelink (SL), and the Us-Rx resources that relay station 1120 can receive over the SL. Cell station 1100 further transmits a resource allocation indicating the Ds resources that the wireless terminal should receive downlink data from. Note that the Ds resource allocation and Us resource allocation may be combined in a single message or in separate messages. ○ In step S111a, the cell station 1100 transmits downlink data in the designated Ds resource, and the wireless terminal 1110 receives and decodes user data in the Ds resource. The Us resource is scheduled some time after the Ds resource so that the wireless terminal 1110 has an opportunity to send feedback data in the assigned Us resource. As discussed in relation to the second embodiment, the Us resource and the Us-Rx resource are assigned in the same message or different messages. As mentioned, in the third embodiment, the Us resource and the Us-Rx resource are identical or substantially overlapping. In the case where a single message assigns both the Us resource and the Us-Rx resource, the single message is a PDCCH message whose CRC is scrambled with a newly defined "Remote-UE-RNTI" identifier, as discussed in relation to the second embodiment. ● In step S112, the wireless terminal 1110 transmits feedback data, such as an acknowledgment (ACK) message or a rejection (NACK) message, to the relay station 1120 via a sidelink (SL), indicating whether the DL data from the cell station 1100 was received correctly (ACK), incorrectly (NACK), or possibly partially incorrectly (e.g., NACK'), respectively. Typically, the cell station 1100 is unable to correctly receive the transmitted data due to transmission restrictions to the wireless terminal 1110, as previously shown. The relay station 1120 receives the feedback data transmission from the wireless terminal 1110 within the Us-Rx resource. Note that the feedback data may also include normal upstream data, as in the two prior embodiments for upstream user data, or MAC control elements such as BSRs. ● In step S113, the relay station 1120 transfers the information to the cell station 1100 directly or indirectly (for example, via a further relay UE). ● In cases where the feedback data indicates a NACK, or alternatively, where the feedback data was not received in time, the cell station 1100, in step S114, optionally retransmits the relevant DL data block in a new resource DL' allocation sent to the wireless terminal 1110, either entirely or partially (in the case of a NACK').

[0150] A fifth embodiment of the present invention, depicted in Figure 12, corresponds to the fourth embodiment, except that the relay station 1220 is currently served by cell station 1201 in cell 12b, which is different from cell station 1200 (in cell 12a) that serves the wireless terminal 1210. Thus, this represents a case in which the wireless terminal 1210 receives downlink user data from a core network having two cell stations that play a role. ● In step S120, cell station 1201 coordinates with other cell stations 1200 regarding downlink user data for wireless terminal 1210 and resource allocation for the next step, as in the third embodiment. Thus, the coordination ensures that the Us resources and Us-Rx resources are equal or at least substantially overlapping. ● In step S121, cell station 1201 sends a communication resource reservation message to wireless terminal 1210 indicating a Us-Rx resource that the relay station needs to receive on the sidelink (SL) for one of its remote UEs. Details of this transmission are similar, for example, to those in the third and fourth embodiments. Relay station 1220 schedules reception on the Us-Rx resource. Optionally, as described in relation to previous embodiments, step S121 may be performed earlier, for example, before step S120. That is, cell station 1201 selects a resource pool for relay station 1220 to monitor the sidelink. Cell station 1201 can therefore signal this to other cell station 1200 in step S120 as part of coordination. Cell station 1200 can then select an available resource in this resource pool.

[0151] Note that, in addition to the resource pool, periodic resource reservations for relay station 1220 should be listened for. This periodic resource reservation is initially configured at relay station 1220 in step S121. Subsequently, the two cell stations 1200 and 1201 coordinate in step S120 if the resources for the periodic reservation are still available for use. Cell station 1201 can, for example, send one or more resource proposals to the other cell station 1200. Cell station 1201 can store this information in a table, for example, listing which of the resource opportunities are still available. Then, in step S122, cell station 1200 can send one specific resource reservation to wireless terminal 1210.

[0152] A variation using a resource pool can function similarly to the periodic resource allocation described above. Cell station 1201 maintains a table of all resources in the pool and which resources are already in use. Therefore, coordination step S120 includes cell station 1201 selecting an available resource from the table and sending this information to other cell stations 1200.

[0153] Alternatively, coordination could simply involve cell station 1201 telling other cell stations 1200 to "choose any resource you like from this pool X," and thus the responsibility for selecting resources rests with cell station 1200. If cell station 1200 is the exclusive user of the resource pool, a conflict is unlikely. However, this is prone to resource conflicts and / or interference if multiple cell stations all use the same resource pool and select resources independently from the resource pool without coordination. To prevent this, cell station 1200 could collect measurements from many UEs, for example, about resource usage / interference levels, in order to correctly select resources. ● In step S122, another cell station 1200 sends a similar message to the wireless terminal 1210 instructing it to use the Us resource. Cell station 1200 then sends a resource reservation to the wireless terminal instructing it to use the Ds resource for receiving downlink (DL) data. This may be in the same or a different message. ○ In step S122a, the cell station 1200 then transmits user data within the designated Ds resource that the wireless terminal receives and decodes. Note that Us resource allocation is signaled before, after, or during the transmission of DL user data.

[0154] Furthermore, steps S121 and S122 may be performed in parallel. ● In step S123, the wireless terminal 1210 sends feedback data, such as an acknowledgment (ACK) message or a rejection (NACK) message, to the relay station 1220 using the Us resource, indicating whether the data from the cell station 1200 was received correctly (ACK), incorrectly (NACK), or partially incorrectly (NACK'), respectively. This feedback is received by the relay station 1220. ● In step S124, the relay station 1220 forwards the feedback information to the cell station 1201 directly or indirectly (for example, via a relay UE - not shown). Optionally, in step S125, cell station 1201 transfers all or part of the feedback data to another cell station 1200. ● In cases where the feedback data indicates NACK / NACK', or alternatively, if the feedback data is not received in time, the cell station 1200 is set up in the next step S126 to retransmit the non-existent / corrupted data to the wireless terminal 1210 with a new resource allocation DL'.

[0155] In certain variations of the previous embodiment, applicable to both single gNB and dual gNB cases, a relay station can send back PHY-level ACK / NACKs, such as HARQ feedback data, to the transmitting cell station on behalf of the wireless terminal, if the relay station is within range of a cell station that directly transmits user data to the wireless terminal. This variation is based on the assumption that the relay station and the wireless terminal are relatively close, for example, in the same area and under roughly the same radio conditions, so that the relay station's feedback has some values ​​indicating how well the wireless terminal received the data transmission from the transmitting cell station. The benefit here is that the transmitting cell station can directly receive feedback at the PHY level on whether the data was received correctly, without having to wait for the above-mentioned PHY-layer feedback information (such as PDCP feedback or feedback information via the IP layer), which can sometimes take a long time to arrive and generate, resulting in latency for DL ​​data.

[0156] The relay station transmits PHY feedback (e.g., HARQ feedback information) autonomously or after receiving a signal from the wireless terminal instructing it to perform its own PHY feedback. HARQ feedback is preferably sent to the transmitting cell station within the HARQ feedback time interval (flexible in 5G, but typically 4ms as in LTE). To achieve this, the relay station receives (from the cell station or the wireless terminal) the RNTI value or other identity information that the cell station uses to send resource-save or downlink messages to the wireless terminal. This allows the relay station to decode the PDCCH resource-save message and be aware of when transmission to the wireless terminal is to take place, and then the relay station can decide to send PHY-level ACK / NACKs, such as HARQ feedback, back to the cell station rather than the wireless terminal. The relay station also receives information from the cell station or from the wireless terminal which is the TX limiter, and / or uses recently received measurement data from the wireless terminal to determine the quality of connection between the wireless terminal and its cell station. This can act as a trigger for the relay station to decide, on behalf of the wireless terminal, when to send ACK / NACK feedback and when not to send it. Alternatively, the relay station may duplicate the HARQ feedback if it is further aware that HARQ feedback is sent between the wireless terminal and the cell station and knows the TX limit status of the wireless terminal (and therefore knows that it is unlikely that HARQ feedback will arrive at the cell station). For this purpose, the relay station receives HARQ process information from the wireless terminal or the cell station to act on behalf of the wireless terminal to ensure that the same HARQ process number and the same subframe are used. In yet another alternative, the wireless terminal sends a signal with information indicating HARQ feedback information to the relay station before the HARQ feedback time interval occurs (e.g., using a sidelink), and the relay station can then transmit the HARQ feedback information to the cell station during the scheduled feedback time interval.

[0157] This means that, for a wireless terminal, upon receiving a PDCCH indicating a scheduled DL transmission, the wireless terminal forwards some or all of the received DCI, such as the HARQ process number and subframe number, to the relay station so that the relay station can provide feedback on behalf of the wireless terminal.

[0158] Similarly, in another variation of the previously discussed embodiment, if a wireless terminal transmits user data directly to a cell station (for example, using an uplink resource U allocated for the wireless terminal but also decodeable by a relay station), the relay station can send a PHY-level ACK / NACK, such as HARQ feedback, to the wireless terminal on behalf of the cell station. For this purpose, the wireless terminal receives HARQ process information (e.g., HARQ process ID, timing / resource information) from the cell station to act on behalf of the cell station to ensure that the same HARQ process number and the same subframe are used. The first or second cell station further provides (e.g., via an RRC message) some security certificates or information about the type, format, encoding, scrambling, or content of the signal or message to enable the relay station to verify the integrity of the message or decode the message / signal (partially), and further provides instruction / policy information that, if (e.g., the CRC or message integrity code / message authentication code is verified to be correct), the relay station is construed to send approval data to the wireless terminal. It should be noted that such policy information is further configured on the device by the core network (for example, through the Policy Control Function (PCF)). The relay station uses the information received from the first or second cell station to perform several processes on the uplink / upstream signals / messages received from the wireless terminal, and if the result of this processing satisfies one or more conditions, it sends approval data to the wireless terminal.Alternatively, the relay station first forwards the received uplink / upstream signal / message to a second cell station to which it is connected (the second cell station then forwards it to the first cell station), and then, if the second cell station (or the first cell station indirectly through the second cell station) successfully receives / decodes / verifies the integrity of the forwarded uplink / upstream signal / message, it sends the signal / message back to the relay station (instead of sending the acknowledgment data directly to the wireless terminal), and therefore the relay station then sends the acknowledgment data to the wireless terminal.

[0159] The guiding assumption for the above solution for sending approval is the (typical) case where the relay station and remote UE are relatively close together, the relay station has a higher incoming signal quality of the wireless terminal's signal, while the cell receives only a very weak signal directly from the wireless terminal. This has the advantage that, in the typical case where the cell station can receive the uplink transmission directly from the wireless terminal, the cell station can respond directly to the feedback information itself, but in the temporary situation where the cell station cannot receive the uplink transmission due to TX limitations, the relay station can receive the uplink data on behalf of the cell station. Furthermore, the relay station can respond on behalf of the cell station with feedback information (e.g., ACK / NACK or HARQ). The relay station will also be responsible for further relaying the uplink data to its cell station so that the uplink data is not lost.

[0160] To accomplish this task, various techniques can be used by relay stations to avoid collisions with potential feedback information sent by cell stations. ● The relay station detects, for example, that a wireless terminal directly performed an uplink transmission, but the cell station did not respond with PHY feedback information within the expected time frame. The relay station then sends this information to the wireless terminal on behalf of the cell station. ● The relay station receives a command from the cell station to begin sending feedback information on behalf of the wireless terminal. This command is triggered, for example, by a measurement at the cell station indicating that the wireless terminal signal is becoming very weak. ● Relay stations use random backoff periods to send feedback data, and cell stations do the same. Feedback responses from relay stations and cell stations will then be separated within a certain timeframe with a certain probability, and if one party realizes that the other party has already responded, the other party is no longer required to respond.

[0161] The overall benefit of this solution is that wireless devices (e.g., low-power IoT devices with resource constraints) do not need to retransmit uplink data lost by a cell station to a cell station or relay station. Reducing the need for retransmission saves energy.

[0162] In an alternative embodiment, multiple cell stations within an area send DL transmissions to a wireless terminal. This results in overlapping data transmissions, thus improving transmission robustness and creating diversity in radio conditions. Consequently, this increases the probability of correct data reception by the wireless terminal. Since a TX-limited wireless terminal cannot directly send back a PHY-level ACK / NACK to one or more of the cell stations, this overlap reduces the probability of incomplete DL data transmissions at the wireless terminal. Furthermore, multiple cell stations can send resource reserve messages to the wireless terminal indicating resource Us' / Us'', each with a specific spectral allocation that the wireless terminal can select from upstream data and use to send the upstream data, and can send the corresponding resource reserve to a nearby relay station to receive the upstream data from the wireless terminal.

[0163] In an alternative embodiment, a cell station capable of reaching a wireless terminal sends relay selection or relay reselection information to the wireless terminal. This information can be encoded in a System Information Block (SIB), RRC message, Downlink Control Information (DCI), or other type of message and includes, for example, the L2 identity and other information of nearby relay stations (e.g., information about the timing / frequency / resources when nearby relay stations send discovery messages (e.g., ProSe / sidelink discovery messages) or when nearby relay stations listen for incoming discovery or "relay participation request" messages). The wireless terminal can use this information to select or reselect the relay station best suited for use. The wireless terminal can further select multiple relay stations as parents, for example, if suggested by the cell station information.

[0164] Such relay selection is particularly useful when a cell station has previously made contact with a wireless terminal (bidirectionally) but has just detected that a TX limitation situation is in effect, i.e., when the wireless terminal's signal has become so weak that it can no longer be received. This could be because the wireless terminal has reduced its transmit power due to low energy or to improve battery life, or because more power is required for another task and the total power budget is limited, or because the wireless terminal has moved and gone out of range. The cell station can then send relay selection information to the wireless terminal in only one direction to help the wireless terminal quickly acquire a relay station.

[0165] Relay reselection is used when a wireless device is already using a relay, but it should choose a better relay parent.

[0166] Additionally, a cell station can schedule resources for a relay station to listen for potential discovery messages or "relay join requests" or other upstream messages (e.g., PC5 signaling messages) from a wireless terminal, where the message indicates that the wireless terminal is looking for a relay station. For this purpose, the cell station also provides the relay station with information about the identity (e.g., L2 identity) that the wireless terminal should use in its discovery message or "relay join request" or upstream message. These scheduled resources are selected from the same range / pool as the resources communicated to the wireless terminal via the SIB / RRC described above. This allows the relay station to more easily and reliably pick up "relay join requests," discovery messages, and / or upstream messages from the wireless terminal. For example, this could mean that the relay station temporarily disabled its relaying function to conserve energy, and after receiving a message indicating a scheduled resource, the relay station decides to allow its relaying function to receive potential relay discovery requests from the wireless terminal again and then potentially serve as a relay station for that terminal.

[0167] Optionally, a cell station sends a message to a relay station requesting it to send an SL discovery message. These messages are intended to be detected by wireless terminals and are therefore available during the relay selection process to choose the best relay station (for example, in terms of signal quality). Messages sent by a cell station act as a trigger for a relay station to enable its relaying function in cases where the relay station was (temporarily) disabled upon receiving the message.

[0168] Furthermore, in order to trigger the cell station to send relay (re)selection information, the cell station optionally requests a one-time high-power "hello" message transmission from the wireless terminal to the cell station to notify the cell station that the wireless terminal is there (at a sustainable lower power level) and needs relaying to send a reply. As soon as the cell station knows that the wireless terminal is somewhere, it can broadcast the relay selection information to be received by the wireless terminal. After relay selection / connection, asymmetric operation according to embodiments of the present invention can begin. This embodiment can only function if the wireless terminal has sufficient Tx power reserves and sufficient energy reserves to send the "hello" message transmission.

[0169] In an alternative embodiment, the wireless terminal intentionally switches to TX-limited mode to conserve energy and / or to prepare for an imminent situation in which it would fall outside of Tx coverage to its cell station. In this case, the cell station has already transmitted repeater selection information to the wireless terminal (for example, before the wireless terminal switches to TX-limited mode), as detailed in the previous embodiment, and the wireless terminal is then able to select and set up a repeater connection. As soon as the repeater connection becomes active, the wireless terminal reduces its Tx power and transmits only to its repeater, rather than directly to the cell station. ● The wireless terminal autonomously determines this and signals the cell station that the wireless terminal will carry out this procedure. ● Alternatively, the cell station signals to the wireless terminal that it needs to perform this procedure (in this case, relay selection information may already be included). This is useful if the cell station, using its advanced RAN measurement and analysis, determines that the wireless terminal is at risk of going out of coverage and there are no other cell stations suitable for handover. For this purpose, the cell station transmits relay selection information or a unique signal for switching to TX-restricted mode, and therefore the unique signal includes the identity of the wireless terminal or the group of wireless terminals to which the wireless terminal belongs. The wireless terminal switches to TX-restricted mode, for example, if the identity of the wireless terminal matches the identity of the wireless terminal or the group of wireless terminals to which the wireless terminal belongs, at the same time as receiving the relay selection information from the cell station or at the same time as receiving the unique signal for switching to TX-restricted mode from the cell station.

[0170] It is important to note that various embodiments of the present invention can be combined with LTE / NR Dual Connectivity (DC), which means simultaneous connection to multiple gNBs / cells. The concept of "Dual Connectivity" (DC) is defined in both 4G and 5G standards. This is a solution that allows wireless terminals such as UEs to connect to two cell stations (in this case, gNBs) simultaneously. Simply put, one of the cell stations is the "master" and the other is the "secondary". In this specification, these are referred to as the Master Cell Group (MCG) and Secondary Cell Group (SCG), as a single cell station is actually a group of cell stations due to the carrier aggregation (CA) feature.

[0171] This solution has several different variations designated for various use cases. For example, these include: ● LTE-NR Dual Connectivity - Allows the UE to connect to, for example, a master LTE eNB while using an additional NR gNB as a secondary cell to obtain spare throughput for downlink. ● NR-NR Dual Connectivity (NR-DC) - Allows a UE to connect to, for example, two NR gNBs, using a secondary gNB for user plane DL traffic at high frequencies such as mmWave, and a master gNB for control plane traffic and UL at low frequencies. This increases DL data rates while providing the UE's UL with stable connectivity to the CN and long-distance, low-power Tx operation.

[0172] As shown in Figure 13, CUE1 and CUE2 are relay UEs, and TUE is a wireless terminal that functions as a remote UE. In this case, downlink data (resource allocation requests, user data, or feedback data) sent from the cell station to the wireless terminal is sent by multiple gNBs.

[0173] In one improved version of various embodiments, the cell station can employ quasi-real-time beam steering (e.g., directed towards a wireless terminal), in which case feedback is sent by the wireless terminal in the form of statistical / measurement reports via an indirect (relayed) path back to the cell station. The feedback is used by the cell station to adapt the beam steering in a closed loop. This is expected to be beneficial only in cases where the wireless terminal is stationary / immobile or moving very slowly, as the feedback information sent via the relay path is slower than the feedback information sent directly.

[0174] In another embodiment, a low-power wireless terminal, such as an NB-IoT or machine-to-machine module (e.g., LTE-M or UE cat.0), receives a (one-way) message directly from the cell station containing configuration information inviting the low-power wireless terminal to connect via a repeater instead of the cell station. This is useful in cases where the low-power wireless terminal has recently lost its connection to the cell station, at least in the uplink direction. Assuming the downlink connection is still operational (receivable by the low-power wireless terminal), the low-power wireless terminal can still receive this configuration message.

[0175] The message may further include information about changes in the wireless terminal's CE mode / repetition rate. The message may further include a security key (for example, stored in an encrypted container message) for securely connecting the wireless terminal directly to a nearby relay station.

[0176] After the low-power wireless terminal selects a repeater from the configuration information, one of the embodiments described previously is used for further communication via the repeater station, i.e., upstream, and for a direct downlink from the cell station.

[0177] In the previously discussed embodiments, wireless terminals can utilize the concept of RF backscatter communication, also known as environmental backscatter (sometimes combined with an energy harvester device). While such backscatter communication methods are beneficial for ultra-low power devices, they typically do not necessarily operate in the absence of any internal energy source during the period in which backscatter communication is used. There are several possible cases (=device classes), all of which fall within the scope of this embodiment. 1. The device has an internal energy source that can be used for normal 3GPP® communications, but has the ability to switch to backscatter communications for a period of time when desired, in order to limit energy consumption from that internal energy source to a very low level, or to not use energy from that internal source at all by using certain forms of energy harvesting, such as RF energy harvesting or vibration energy harvesting. 2. The device has no internal energy source; the only available energy source is, for example, energy harvesting via RF waves. 3. The device has no internal energy source, but in addition to harvesting from, for example, RF waves or vibration energy, it also has other intermittent external energy sources such as solar or wind energy. During times when the mentioned external energy sources do not provide sufficient energy, the device can fall back to harvesting from, for example, RF waves or vibration energy.

[0178] A cell station can directly provide a strong RF signal to a wireless terminal to deliver data to the wireless terminal and to provide energy to the wireless terminal's RF harvester. The cell station may determine at some point that the wireless terminal is a TX limiter and capable of using backscatter communication (using one of the previously instructed methods, such as capability or status information received from the wireless terminal, identity information (e.g., a device belonging to a specific group of TX limiter devices and / or backscatter devices), or information received from the UDM or via the NEF), and therefore the cell station may instruct the relay station and / or the wireless terminal to initiate or switch to backscatter communication by one or more of the following, for example: 1. To provide an extended configuration for discovery message monitoring in RRC signaling (e.g., SIB19 extension or dedicated). 2. Sending normal configuration messages to a wireless terminal, for example using RRC for configuration messages, without using backscatter communication, while the wireless terminal is still directly or indirectly connected to the cell station as a remote UE. Note that this only works if the wireless terminal is capable of being in a non-backscatter communication mode. 3. Send a configuration message to the relay station to instruct it to begin listening for backscatter communications from the wireless terminal, and, if necessary, to instruct it to transmit enough RF energy to be generated by the RF energy harvester of the wireless terminal. 4. Sending / broadcasting a signal (e.g., SIB or awakening signal) to a wireless terminal that indicates the use of backscatter communication mode (e.g., by setting the backscatter communication mode bit), and / or the identity of the wireless terminal (e.g., L2 identity, SUCI / SUPI / GUTI, or RNTI), or the identity of the group of devices to which the wireless terminal belongs (e.g., L2 group identity). 5. Send / broadcast configuration information to the wireless terminal (e.g., as part of the SIB) including conditions / policies that the wireless terminal should apply to decide whether to use backscatter communication (e.g., RSRP threshold or maximum number of failed uplink transmissions).

[0179] The above message must be encrypted (for example, using a pre-shared key or a public key received from the first cell station (signed by the core network or certificate authority), or using a previously used key or a key derived from a previously used key (for example, based on Kamf, Kausf, or ProSe remote user key (PRUK))) in order to prevent a malicious device from using such a message to force a wireless terminal to switch to backscatter communication. The above message further includes additional information about which (type) of signals the cell station will use to enable backscatter communication by the wireless terminal, and / or how the backscatter signal should be transmitted by the wireless terminal (e.g., which modulation or signal encoding or scrambling or transmit power to use, which signal processing algorithm (indicated by, for example, an algorithm identifier) ​​to apply, which time delay to apply, which frequency modification to apply, which multiplexing method to apply, which particular type of signal / message to use by the cell station or which particular type of upstream signal / message is expected to be transmitted for use by the wireless terminal (e.g., a sidelink discovery message), which L1 / L2 source or target identity information (or other identity information such as user information ID, PRUK ID, SUCI, SUPI, GUTI, or RNTI) to use in the upstream signal / message (e.g., relay station identity), or which particular security certificate to use for the message, for example, information about how the signal received from the cell station should be adapted / processed to the backscatter signal).

[0180] A wireless terminal decides to use backscatter communication using one or more of the above messages (for example, to receive DL signals coming from a cell station, and to process the signal so that the wireless terminal can construct an upstream signal containing data / control information (e.g., through multiplexing, signal manipulation) that the wireless terminal wishes to transmit upstream to the cell station via a relay station), and configures its receiver and transmitter and signal processing accordingly. Since backscatter signals are not reflected directly toward the cell station, the wireless terminal deploys two sets of antennas (e.g., an antenna for receiving DL signals from the cell station coming from one direction and an antenna for transmitting upstream signals to the relay station in the other direction), or a single set of antennas that intermittently switches between a mode for receiving DL signals from the cell station and a mode for transmitting upstream signals to the relay station. For this purpose, the wireless terminal is configured by the cell station with (estimated) location information (e.g., geographic or relative coordinates, or distance / direction from a reference point) and / or directional information (e.g., the angle between the incoming DL signal from the cell station and the outgoing upstream signal to the relay station, the transmission angle relative to the reference line or magnetic north of the DL signal or upstream signal). This allows the wireless terminal to configure its antenna appropriately and receive signals from the correct direction / transmit signals in the correct direction (e.g., by changing the beamforming characteristics of the transmitted signal). The wireless terminal is further configured by the cell station with information about the timing of mode switching (e.g., based on normal intervals or with respect to resources scheduled for downlink and upstream communication). This is useful in cases where the antenna switches between a mode for receiving DL signals from the cell station and a mode for transmitting upstream signals to the relay station. Alternatively, the wireless terminal deploys one or more omnidirectional antennas, in which case location / angle is not necessary and is ignored.However, in the case of a single omnidirectional antenna, mode switching is applied, and the wireless terminal is configured with information about the timing of the mode switching as appropriate.

[0181] A cell station assigns identifiers in the security context of its PLMN to identify nearby wireless terminals and relay stations capable of supporting backscatter communication. A cell station can select backscatter-enabled relay stations, for example, by: ● Proximity discovery data received by a cell station, either directly from the wireless terminal (in cases where the wireless terminal is not yet TX-limited but will soon need to switch to TX-limited mode), or from the wireless terminal via the relay station (in cases where the wireless terminal is already functioning as a remote UE for a relay station before switching to backscatter communication), or directly from the relay station (for example, when the relay station reports that it has detected a nearby wireless terminal that is capable of backscatter communication), or from another cell station. ● History data indicating wireless terminals and their priority list for past relay stations. ● The relay station selected by the user. ● Detection of a dedicated backscatter communication-enabled relay station (symbiotic node) located near the wireless terminal, which can be selected by the wireless terminal as the relay station to be used. ● Based on capability information from a connected relay station or a UE capable of becoming a relay station, or capability information provided through application functions, NEFs, or information from the UDM.

[0182] The cell station constitutes a relay station in the vicinity of the wireless terminal by transmitting backscatter communication control information (BCI) to define the properties of the PHY / MAC, for example, within SIB18, or otherwise. ● System information for backscatter communication (e.g., modulation format used, coding scheme, frequency, schedule, etc.). ● Backscatter communication channel allocation and its corresponding SL-channel mapping. ● A multiple UE backscatter communication connection in which backscatter signals from wireless terminals that are subsequently forwarded to a cell station and aggregated can be received by multiple nearby relay stations. ● A congestion mitigation technique configured to prevent multiple wireless devices from simultaneously transmitting backscatter signals in order to avoid interference.

[0183] In backscatter communication modes, the energy required for a wireless terminal to reflect or modulate a signal toward a relay station is typically derived from the RF signal of the cell station. Information about the power generated or received signal strength / bandwidth / frequency / density available to the wireless terminal (remote UE) is used to select device-specific scheduling, modulation format, transmit power, coding scheme, protection mechanism, and connection termination instructions. For example: ● The wireless terminal autonomously determines such a set of parameters based on the available energy while it is already operating on RF-generated energy. ● While still in non-backscatter communication mode, the wireless terminal first measures the incoming RF power and / or other signal characteristics and reports them to the cell station (directly or indirectly via its relay station). The cell station then proposes the parameters to be used and transmits them to the wireless terminal. When the wireless terminal then begins using RF backscatter communication mode, it will use the parameters specified for transmission. ● The cell station provides the wireless terminal with configuration information (e.g., via SIB or RRC) about the set of parameters to be used for different levels of available RF generated energy, and / or different RF signal strength / bandwidth / frequency / density, and / or different RF signal types. The wireless terminal uses this configuration information to select the set of parameters to be used for the upstream signal to the relay station. These parameters differ for each cell or synchronous signal block (SSB).

[0184] Once a period of backscatter communication is successfully completed, the involved devices are returned to their normal state. For example, as follows: ● The TX limiting operation returns to one without backscatter communication as specified in this invention. ● Returns to operating as a wireless terminal directly connected to a cell station, without using a relay station. ● Use both direct cell station connections and one or more relay connections, or just one or more relay connections.

[0185] When a wireless terminal ceases using RF backscatter communication, the relay station optionally continues to listen for backscatter signals / requests from pre-authorized wireless terminals that exist within a pre-established security context. This is useful, for example, for detecting devices that can only use RF backscatter communication at this time, devices that have entered the vicinity of the relay station, and devices that need to communicate. For this purpose, pre-authorized wireless terminals must use a unique identity or certificate in their discovery, relay join request, or other upstream signals / messages (e.g., PC5 signaling messages). To enable the relay station to verify that a wireless terminal is pre-authorized, the relay station configures the corresponding information or remembers the corresponding information from previous communications with the wireless terminal (e.g., using the same or induced PC5 session key). Alternatively, the relay station forwards incoming RF backscatter communications to the cell station to which it is connected and / or to the core network for further processing and to further check whether the wireless terminal is pre-authorized.

[0186] In other words, in order to enable RF backscatter communication, the wireless terminal is configured to communicate over a cellular network, the cellular network further comprising at least one first cell station serving a first cell and at least one relay station served by a second cell station serving a second cell. Wireless devices, A controller adapted to generate uplink information, which operates in backscatter communication mode and has the capability to configure receivers and transmitters, A receiver adapted to receive a first downlink signal in backscatter communication mode, which is transmitted directly by a first cell station and carries each first downlink control information, wherein at least one of the first downlink control information includes at least an instruction for a first resource and / or configuration parameter (e.g., unique modulation) to be used by a wireless terminal to transmit a second signal directly to a relay station, and at least one of the first downlink control information includes at least a second allocated downlink resource to be used by a wireless terminal to receive further downlink signals directly from the first cell station, The system comprises a transmitter adapted to transmit a second signal to a relay station on a first resource carrying uplink information to be forwarded to a second cell station in backscatter communication mode, and a receiver further adapted to receive additional downlink signals directly from the first cell station on a second allocated downlink resource. Optionally, the controller initiates backscatter communication mode operation after the receiver receives a downlink signal transmitted directly by the first cell station, which indicates or includes a trigger to activate backscatter communication mode. Another option is for the controller to initiate backscatter communication mode operation if the transmit or receive operation meets one or more (pre-configured) signal strength / receive quality thresholds or signal transmission failure thresholds, or if the energy level of the wireless terminal falls below a certain threshold, or if a relay station is discovered. Yet another option is for the transmitter to transmit an initial signal directly to the first cell station or relay station, indicating or including a trigger to activate backscatter communication mode.

[0187] The controller is further adapted to obtain energy from the incoming downlink signal and / or to perform signal processing on the incoming downlink signal from the first cell station, and so the controller processes the incoming signal to produce an output signal that includes or multiplexes uplink information, and so the output signal (i.e., the upstream signal / message to be received by the relay station) carries the uplink information.

[0188] As a further option, the receiver and transmitter operate different sets of antennas, respectively, and the controller instructs the transmitter to perform beamforming toward the relay station based on, for example, the relay station's location and / or angular information (e.g., the angle between the beam used for downlink signals from the cell station, such as those received by wireless terminals, and the beam used for upstream signals directed toward the relay station). Such location or angular information is received from the first cell station and / or relay station.

[0189] As a further option, the controller has the capability to operate alternately according to a backscatter communication mode and a second operating mode, and to configure the receiver and transmitter to operate in the selected mode, wherein the receiver is adapted to receive a second downlink signal that is sent directly by the first cell station in the second operating mode, and which carries each second downlink control information, and at least one of each second downlink control information includes at least an indication of a third allocated uplink resource to be used by the wireless terminal to transmit the first uplink signal directly to the first cell station, and at least one of each second downlink control information However, the configuration includes at least an indication of a fourth allocated downlink resource to be used by a wireless terminal to receive further downlink signals directly from the first cell station, wherein the transmitter is adapted in a second operating mode to transmit to the first cell station over a third allocated uplink resource for direct communication to the first cell station, and the receiver is configured by the controller to receive further downlink signals directly from the first cell station over a fourth allocated downlink resource, so that the signal transmitted uplink to the first cell station is a reflected backscatter signal, which is processed by the controller to carry uplink information.

[0190] As mentioned throughout this description, the embodiments and variations of the present invention relate to the context of the 3GPP® 5G standard. They are applicable below. ● Medical applications / connected healthcare involving multiple wireless (4G / 5G) connected sensor nodes or actuator nodes. ● For example, small-form-factor medical applications / connected healthcare devices such as HealthDot patches with built-in detectors that should be placed on the skin. ● Typical IoT applications involving wireless, mobile, or fixed sensor or actuator nodes. ○ For example, smart cities, logistics, agriculture, etc. ○ Generally, any IoT application where the UE needs to be low-power, inexpensive, or have a small form factor. ● Emergency services, public services, and critical communication applications. ● A typical V2X system. ● Specifically, a V2P system, in this case a person (P) carries a wireless terminal with limited battery capacity and / or limited transmission power. ● Improved coverage for 5G cellular networks using high-frequency (e.g., mmWave) RF communication. ● Any other application area of ​​4G / 5G communication where relay stations are used.

[0191] It should be noted that the embodiments described above are not limited to devices outside of coverage. They are beneficial to any wireless terminal even when operating within cell coverage. In practice, as previously explained, for example, using indirect links allows for lower energy consumption communication, while using direct links simultaneously avoids the monitoring / detection costs of sidelink resources, thus giving wireless terminals the ability to reduce the amount of power required for operation.

[0192] Furthermore, it will be understood by those skilled in the art that, in general, the terms used herein and especially in the appended claims are intended to be “open” terms, for example, that the term “includes” should be interpreted as “includes but not limited to,” the term “has” should be interpreted as “has at least,” and the term “equipped” should be interpreted as “equipped but not limited to,” and so on. Where a particular number of introduced claims are intended to be enumerated, such intent will be explicitly enumerated in the claims, and where there is no such enumeration, such intent will not be present, as will be understood by those skilled in the art. For example, for the sake of understanding, the following appended claims include the use of the introductory phrases “at least one” and “one or more” to introduce a list of claims. However, the use of such phrases should not be interpreted as suggesting that the introduction of a claim enumeration by the indefinite article "a" or "an" is intended to limit any particular claim containing such an enumeration to an implementation that contains only one such enumeration, even when the same claim contains the introductory phrase "one or more" or "at least one" and an indefinite article such as "a" or "an". For example, "a" and / or "an" should be interpreted as meaning "at least one" or "one or more", and the same applies to the use of the definite article used to introduce a claim enumeration. Furthermore, in examples where a similar convention to "at least one of A, B, and C" is used, it is generally intended that such a structure is understood by those skilled in the art, for example, "a system having at least one of A, B, and C" includes, but is not limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or systems having A, B, and C together.In examples where a similar convention is used to "at least one of A, B, or C," it is generally intended that such a structure is understood by those skilled in the art, for example, "a system having at least one of A, B, or C" includes, but is not limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or systems having A, B, and C together. It will further be understood by those skilled in the art that any separate word and / or phrase presenting two or more alternative terms in practice should be understood as presuming the possibility of including one of the terms, either one or both of the terms, whether in this description, claims, or drawings. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B."

[0193] The devices are executed by program code means of a computer program and / or as dedicated hardware for the associated devices. The computer program is stored and / or distributed on a suitable medium, such as an optical storage medium or a solid-state medium, supplied together with or as part of other hardware, but may be further distributed in other forms, such as via the Internet or other wired or wireless telecommunications systems.

Claims

1. A wireless terminal for communication over a cellular network, wherein the cellular network comprises at least one first cell station serving a first cell, and at least one relay station served by a second cell station serving a second cell. The aforementioned wireless terminal, A controller operating in TX-limited operation mode, comprising a controller that generates uplink information, A receiver configured by a controller to receive a first downlink signal directly transmitted by the first cell station in TX-restricted operation mode, the first downlink signal carrying each of the first downlink control information, wherein at least one of the first downlink control information includes at least an instruction for a first configuration parameter to be used by the wireless terminal to transmit a signal directly to the relay station, and at least one of the first downlink control information includes at least a second configuration parameter to be used by the wireless terminal to receive further downlink signals directly from the first cell station, In the TX limiting operation mode, the transmitter configured by the controller transmits a second signal carrying the uplink information to be forwarded to the second cell station to the relay station using the first configuration parameters. Equipped with, The receiver further receives the additional downlink signal directly from the first cell station using the second configuration parameter. Wireless terminal.

2. The wireless terminal according to claim 1, wherein the controller starts the TX limiting operation mode after the receiver receives the TX limiting operation mode activation signal, which is a downlink signal sent directly by the first cell station that instructs or triggers the activation of the TX limiting operation mode.

3. The wireless terminal according to claim 1 or 2, wherein the controller starts TX limiting operation mode when the transmission or reception operation satisfies one or more pre-configured signal strength / signal reception quality thresholds or one or more signal transmission failure thresholds, when the energy level of the wireless terminal falls below a specific threshold, or when the relay station is discovered.

4. The wireless terminal according to claim 1 or 2, wherein the transmitter transmits an initial signal to the first cell station and / or the relay station that instructs or triggers the activation of the TX limiting operation mode.

5. The controller operates alternately according to the first operating mode and the second operating mode, which are the TX limiting operating modes. The receiver is adapted to receive, in the second operating mode, a second downlink signal directly transmitted by the first cell station, the second downlink signal carrying each second downlink control information, wherein at least one of the second downlink control information includes at least an indication of a third configuration parameter to be used by the wireless terminal to directly transmit an uplink signal to the first cell station, and at least one of the second downlink control information includes at least an indication of a fourth configuration parameter to be used by the wireless terminal to directly receive further downlink signals from the first cell station. The aforementioned controller generates uplink information, The wireless terminal according to claim 1 or 2, wherein the transmitter is configured by the controller to transmit to the first cell station using the third configuration parameter for direct communication to the first cell station in the second operating mode, and the receiver is configured by the controller to directly receive the further downlink signal from the first cell station using the fourth configuration parameter.

6. The wireless terminal according to claim 5, wherein the receiver further receives a third downlink signal transmitted by the first cell station, the third downlink signal carrying third downlink control information, the third downlink control information includes at least an indication of a downlink resource where user data transmitted by the first cell station is scheduled to be received, and the controller configures the receiver to receive the user data.

7. The wireless terminal according to claim 6, wherein the uplink information includes approval data based on a determination of whether the user data has been successfully decoded, and the approval data is transmitted by the transmitter to the first cell station using the third configuration parameter when the controller is operating in the second operating mode, or to the relay station using the first configuration parameter when the controller is operating in the first operating mode.

8. The wireless terminal according to claim 5, wherein the uplink information includes at least one uplink user data packet, the user data packet is sent directly to the first cell station in the second operating mode, and the user data packet is forwarded to the second cell station by the relay station in the first operating mode.

9. The wireless terminal according to claim 8, wherein the receiver receives further downlink control information including an instruction on whether the uplink user data packet has been successfully decoded.

10. The wireless terminal according to claim 1 or 2, wherein the first cell station and the second cell station are a single cell station.

11. The wireless terminal according to claim 1 or 2, wherein the transmitter uses backscatter communication.

12. A first cell station serving a first cell, At least one relay station served by a second cell station serving a second cell, The wireless terminal served by the first cell station and A cellular communication system equipped with, The first cell station comprises a first cell station transmitter for directly transmitting a first downlink signal carrying first downlink control information to the wireless terminal, wherein the first downlink control information includes at least an indication of first configuration parameters to be used by the wireless terminal to transmit the signal to the relay station. The second cell station comprises a second cell station transmitter for transmitting a second downlink signal carrying second downlink control information to the relay station, wherein the second downlink control information includes at least an indication of a second configuration parameter to be used by the relay station to receive the signal from the wireless terminal, and the first and second configuration parameters overlap at least partially. The wireless terminal comprises a wireless terminal controller that generates uplink information, and a wireless terminal transmitter configured by the wireless terminal controller to transmit a message carrying the uplink information to the relay station using the first configuration parameter, The relay station includes a relay station receiver that receives the message using the second configuration parameter. Cellular communication system.

13. The cellular communication system according to claim 12, wherein the relay station comprises a relay station transmitter for transmitting a relay message including the uplink information to the second cell station.

14. The cellular communication system according to claim 13, wherein the second cell station transmits a third downlink signal to the relay station carrying third downlink control information, the third downlink control information includes at least an indication of a third configuration parameter used by the relay station to transmit the relay message to the second cell station.

15. The cellular communication system according to claim 14, wherein the first downlink signal and the second downlink signal are a single downlink signal received by the wireless terminal and the relay station.

16. The cellular communication system according to claim 14 or 15, wherein the second downlink signal and the third downlink signal are a single downlink signal received by the relay station.

17. The cellular communication system according to any one of claims 12 to 15, wherein the message carrying the uplink information includes at least one uplink user data packet to be forwarded by the relay station to the second cell station.

18. A relay station operating in a cellular communication network comprising at least one first cell station serving a first cell and a wireless terminal served by the first cell station, The relay station is served by a second cell station that serves a second cell. The aforementioned relay station, A relay station receiver that receives a second downlink signal from the second cell station that carries second downlink control information, wherein the second downlink control information includes at least one instruction for a first configuration parameter for receiving a message from the wireless terminal, A relay station controller for controlling the receiver of the relay station to receive the message containing uplink information in the first configuration parameter, A relay station transmitter that transfers the uplink information in the relay data message to the second cell station. A relay station equipped with these features.

19. A cellular communication system comprising a wireless terminal served by a first cell station and at least one relay station served by a second cell station serving a second cell, wherein the first cell station serving the first cell is a first cell station serving a first cell, The first cell station, A first cell station transmitter for transmitting a first downlink signal carrying first downlink control information to the wireless terminal, wherein the first downlink control information includes at least an indication of first configuration parameters to be used by the wireless terminal to transmit a message to a relay station, A first cell station controller for configuring the relay station with second downlink control information, wherein the second downlink control information includes at least instructions for a second configuration parameter to be used by the relay station to receive the message from the wireless terminal, and the first and second resources at least partially overlap the first cell station controller and A first cell station equipped with [the following].

20. A method for operating a wireless terminal to communicate in a cellular network comprising at least one first cell station serving a first cell and at least one relay station served by a second cell station serving a second cell, The aforementioned method, The steps include: the wireless terminal receiving a downlink signal transmitted by the first cell station, the downlink signal carrying downlink control information, wherein the downlink control information includes at least an indication of a first configuration parameter to be used by the wireless terminal to transmit a message to the relay station; The steps include: generating uplink information in the wireless terminal; The steps include: the wireless terminal transmitting the message carrying the uplink information to the relay station using the first configuration parameter, wherein the uplink information is transferred to the second cell station; A method having.

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