BACKGROUND OF THE INVENTION

One of the main requirements for 5G is to improve the link reliability and quality-of-service. For this reason, hybrid automatic repeat request (hybrid ARQ or HARQ) is an important process to maintain reliable communication and to guarantee the most possible error correction and decoding capabilities. However, HARQ itself is a complicated process that needs to compute different redundancy versions of an initial transmission.

Once the transmitter node (base-station or a mobile station) receives a negative acknowledgement (NACK), it will automatically retransmit a new version of the previously transmitted transport block (TB) composed of different arrangements of redundancy bits and data bits.

The plurality of HARQ or ARQ approaches have been discussed within known technology: HARQ process and ARQ process is covered in [LTE-36212] [LTE-36211], dual connectivity and multi-connectivity is part of literature [CD-MC], buffer for satellite broadcast is part of literature [Relay], donor base station and remote base station is part of literature [Rel11], resource allocation resource grating in time and frequency is the state of the ART. [LTE36213].

A critical feature of the HARQ process is that it has a critical timely manner. This means that if acknowledgement (ACK) is not received within a given window, the transmitted might be forced to (unnecessarily) send retransmission again. This will be very critical in satellite communication where the round-trip-time (RTT) already exceeds the maximum possible time window size. Even more difficult will be compensating this RTT delay, which will result in 4 to 15 times more parallel HARQ process compared to normal terrestrial communication; this might be practically infeasible.

Another problem in the HARQ process is that it keeps the uplink channel of the ground mobile set/user equipment (UE) busy with allocating resources in the satellite links in the backward direction. This will cause an inefficient and power-hungry process. Therefore, there is a need for an improved approach.

SUMMARY

An embodiment may have a user equipment of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the user equipment including a transceiver which includes: a non-terrestrial signal receiver configured to receive the data packet from the non-terrestrial node; a unit for analyzing the signal quality of the data packet, said unit being configured to generate the acknowledgement command in case of a sufficiently correct reception of the data packet or to generate the non-acknowledgement command in case of an incorrect reception of the data packet; and a terrestrial signal transmitter configured to transmit the acknowledgement command or the non-acknowledgement command to the terrestrial node in order to initiate using the non-acknowledgement command a retransmission of the data packet and/or a redundancy version of the data packet.

Another embodiment may have a method for operating a user equipment of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method including the following steps: receiving a data packet using a non-terrestrial signal receiver; analyzing the signal quality of the data packet and generating the acknowledgment command in case of a sufficiently correct reception of the data packet or generating a non-acknowledgement command in case of an incorrect reception of the data packet; and transmitting the acknowledgment command or the non-acknowledgment command to the terrestrial node using a terrestrial signal transmitter in order to initiate using the non-acknowledgment command a retransmission of the data packet or a retransmission of a redundancy version of the data packet.

Another embodiment may have a terrestrial node of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the terrestrial node, the terrestrial node including: a non-terrestrial signal receiver configured to receive the data packet or a redundancy version of the data packet from the non-terrestrial node; a memory configured to buffer the data packet or the redundancy version of the data packet; a terrestrial signal receiver configured to receive the acknowledgement command or the non-acknowledgement command from the user equipment; and a terrestrial signal transmitter configured to retransmit the data packet or a redundancy version of the data packet to the user equipment as response to the non-acknowledgment command.

Another embodiment may have a method for operating a terrestrial node a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method includes the following steps: receiving the data packet or a redundancy version of the data packet from the non-terrestrial node using a non-terrestrial signal receiver; buffering the data packet or the redundancy version of the data packet using a memory; receiving the acknowledgment command and/or the non-acknowledgment command from the user equipment using the terrestrial signal receiver; and retransmitting the buffered data packet or the buffered redundancy version of the data packet to the user equipment using a terrestrial transceiver as response to the non-acknowledgment command.

Another embodiment may have a satellite of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the satellite includes a transceiver including: one or more transmitters, wherein the one or more transmitters are configured to transmit the data packet to the user equipment and to transmit the data packet or a redundancy version of the data packet to the terrestrial node.

Another embodiment may have a method operating a satellite of system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method including the steps: transmitting the data packet to the user equipment; and transmitting the data packet or a redundancy version of the data packet to the terrestrial node.

Another embodiment may have a satellite of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment as well as a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the satellite includes a memory which is configured to buffer the data packet to be sent to the user equipment and/or a redundancy version of the data packet.

Another embodiment may have a method for operating a satellite or system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment as well as a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method includes the following steps: buffering the data packet or a redundancy version of the data packet by a memory of the satellite; and/or forwarding the data packet or the redundancy version of the data packet to a terrestrial node, such that the terrestrial node buffers the data packet or the redundancy version of the data packet.

Another embodiment may have a HARQ controller of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the HARQ controller is configured to control the buffering performed a memory of the satellite and/or by a memory of the terrestrial node.

Another embodiment may have a gateway of a system, the system including at least a ARQ controller according to one of the claims28-31, the gateway including a further HARQ controller and/or an ARQ controller; or wherein the gateway includes an ARQ controller receiving acknowledgement command and the non-acknowledgement command relayed back to the satellite by the terrestrial node in order to satisfy the automatic repeat request ARQ of upper layers.

Another embodiment may have a method for operating a HARQ controller of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, wherein the method includes the steps: buffering the data packet or a redundancy version of the data packet to a memory of the satellite; and/or buffering the data packet or the redundancy version of the data packet to a memory of the terrestrial node.

Another embodiment may have a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes s a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for operating a user equipment of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method including the following steps: receiving a data packet using a non-terrestrial signal receiver; analyzing the signal quality of the data packet and generating the acknowledgment command in case of a sufficiently correct reception of the data packet or generating a non-acknowledgement command in case of an incorrect reception of the data packet; and transmitting the acknowledgment command or the non-acknowledgment command to the terrestrial node using a terrestrial signal transmitter in order to initiate using the non-acknowledgment command a retransmission of the data packet or a retransmission of a redundancy version of the data packet, when said computer program is run by a computer.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for operating a terrestrial node a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method includes the following steps: receiving the data packet or a redundancy version of the data packet from the non-terrestrial node using a non-terrestrial signal receiver; buffering the data packet or the redundancy version of the data packet using a memory; receiving the acknowledgment command and/or the non-acknowledgment command from the user equipment using the terrestrial signal receiver; and retransmitting the buffered data packet or the buffered redundancy version of the data packet to the user equipment using a terrestrial transceiver as response to the non-acknowledgment command, when said computer program is run by a computer.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method operating a satellite of system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method including the steps: transmitting the data packet to the user equipment; and transmitting the data packet or a redundancy version of the data packet to the terrestrial node, when said computer program is run by a computer.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for operating a satellite or system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment as well as a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method includes the following steps: buffering the data packet or a redundancy version of the data packet by a memory of the satellite; and/or forwarding the data packet or the redundancy version of the data packet to a terrestrial node, such that the terrestrial node buffers the data packet or the redundancy version of the data packet, when said computer program is run by a computer.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for operating a HARQ controller of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, wherein the method includes the steps: buffering the data packet or a redundancy version of the data packet to a memory of the satellite; and/or buffering the data packet or the redundancy version of the data packet to a memory of the terrestrial node, when said computer program is run by a computer.

Another embodiment may have a terrestrial node of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment via a non-terrestrial channel, wherein the user equipment is configured to analyze a channel quality of the non-terrestrial channel and to transmit an information regarding the channel quality of the non-terrestrial channel to the base station, the terrestrial node including: a non-terrestrial signal receiver configured to receive the data packet or a redundancy version of the data packet from the non-terrestrial node; a memory configured to buffer the data packet or the redundancy version of the data packet; a terrestrial signal receiver configured to receive the information regarding the channel quality of the non-terrestrial channel from the user equipment; and a terrestrial signal transmitter configured to retransmit the data packet or a redundancy version of the data packet to the user equipment as response to a channel quality of the non-terrestrial channel below a threshold.

Another embodiment may have a method for operating a terrestrial node a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment via a non-terrestrial channel, wherein the user equipment is configured to analyze a channel quality of the non-terrestrial channel and to transmit an information regarding the channel quality of the non-terrestrial channel to the base station, the method includes the following steps: receiving the data packet or a redundancy version of the data packet from the non-terrestrial node using a non-terrestrial signal receiver; buffering the data packet or the redundancy version of the data packet using a memory; receiving the information regarding the channel quality of the non-terrestrial channel from the user equipment using the terrestrial signal receiver; and retransmitting the buffer data packet or the buffered redundancy version of the data packet to the user equipment using a terrestrial transceiver as response to a channel quality of the non-terrestrial channel below a threshold.

Another embodiment may have a terrestrial node of a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment as well as a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the terrestrial node including: a terrestrial signal receiver configured to receive another data packet from the user equipment, the other data packet is to be transmitted to the gateway; a unit for analyzing the signal quality of the other data packet, said unit being configured to generate an acknowledgement command in case of a sufficiently correct reception of the data packet or to generate an non-acknowledgement command in case of an incorrect reception of the data packet; and a terrestrial signal transmitter configured to transmit the acknowledgement command or the non-acknowledgement command to the user equipment in order to initiate using the non-acknowledgement command a retransmission of the other data packet and/or a redundancy version of the other data packet, wherein parallel resources are used for the retransmission; further including a controller configured to choose or adapt the modulation and coding scheme in accordance to the communication requirements of the transmission between the user equipment and the terrestrial node and in accordance to the communication requirements of the transmission between the terrestrial node and the non-terrestrial node.

Another embodiment may have a method for operating a terrestrial node a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment as well as a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method includes the following steps:

receiving another data packet from the user equipment using a non-terrestrial signal receiver, the other data packet is to be transmitted to the gateway; analyzing the signal quality of the other data packet and generating an acknowledgement command in case of a sufficiently correct reception of the data packet or generating an non-acknowledgement command in case of an incorrect reception of the data packet; transmitting the acknowledgement command or the non-acknowledgement command to the user equipment using a terrestrial signal transmitter to in order to initiate using the non-acknowledgement command a retransmission of the other data packet and/or a redundancy version of the other data packet, wherein parallel resources are used for the retransmission; and choosing or adapting the modulation and coding scheme in accordance to the communication requirements of the transmission between the user equipment and the terrestrial node and in accordance to the communication requirements of the transmission between the terrestrial node and the non-terrestrial node.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for operating a terrestrial node a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment, wherein terrestrial node includes a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment via a non-terrestrial channel, wherein the user equipment is configured to analyze a channel quality of the non-terrestrial channel and to transmit an information regarding the channel quality of the non-terrestrial channel to the base station, the method includes the following steps: receiving the data packet or a redundancy version of the data packet from the non-terrestrial node using a non-terrestrial signal receiver; buffering the data packet or the redundancy version of the data packet using a memory; receiving the information regarding the channel quality of the non-terrestrial channel from the user equipment using the terrestrial signal receiver; and retransmitting the buffer data packet or the buffered redundancy version of the data packet to the user equipment using a terrestrial transceiver as response to a channel quality of the non-terrestrial channel below a threshold, when said computer program is run by a computer.

Another embodiment may have a non-transitory digital storage medium having a computer program stored thereon to perform the method for operating a terrestrial node a system, the system including a gateway, a non-terrestrial node, a terrestrial node and at least a user equipment as well as a HARQ controller, wherein the gateway is configured to forward a data packet, said data packet to be transmitted to the user equipment, to the non-terrestrial node, wherein the non-terrestrial node is configured to forward the received data packet to the user equipment using a signal, wherein the user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node with regard to a signal quality and to generate a negative acknowledgment command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality, wherein the user equipment is configured to transmit the acknowledgement command and the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node, the method includes the following steps: receiving another data packet from the user equipment using a non-terrestrial signal receiver, the other data packet is to be transmitted to the gateway; analyzing the signal quality of the other data packet and generating an acknowledgement command in case of a sufficiently correct reception of the data packet or generating an non-acknowledgement command in case of an incorrect reception of the data packet; transmitting the acknowledgement command or the non-acknowledgement command to the user equipment using a terrestrial signal transmitter to in order to initiate using the non-acknowledgement command a retransmission of the other data packet and/or a redundancy version of the other data packet, wherein parallel resources are used for the retransmission; and choosing or adapting the modulation and coding scheme in accordance to the communication requirements of the transmission between the user equipment and the terrestrial node and in accordance to the communication requirements of the transmission between the terrestrial node and the non-terrestrial node, when said computer program is run by a computer.

The invention is based on the general concept of a system which comprises a gateway, a non-terrestrial node or entity, like a satellite or high altitude platform, a terrestrial node, especially a terrestrial base station, and at least a user equipment. Furthermore, the system comprises a HARQ controller and the gateway. The gateway is configured to forward at least a data packet which should be transmitted to the user equipment, to the non-terrestrial node, such that the non-terrestrial node can forward the at least one received data packet to the user equipment. The user equipment is configured to analyze the received data packet with regard to a transmission error and/or to analyze the signal from the non-terrestrial node (10) with regard to a signal quality and to generate a negative acknowledgement command or an acknowledgement command dependent on the transmission error or to generate another signal indicating the reception signal quality dependent on the reception signal quality of the at least one received data packet. The user equipment is further configured to transmit the acknowledgement command and/or the non-acknowledgement command or the other signal to the terrestrial node which communicates with the non-terrestrial node.

Embodiments assume a scenario where the user-equipment/UE-to-Network-Relay/mobile-station is connected to (5G) Satellite mobile services while keeping a terrestrial connection doubly (multiply) connected to it. Here, a first aspect refers to the user equipment of the system. The user system comprises a transceiver comprising a non-terrestrial signal receiver, means for analyzing the signal quality of the at least one data packet and a terrestrial signal transmitter. The non-terrestrial signal receiver is configured to receive the at least one data packet from the non-terrestrial node. The at least one data packet is analyzed with regard to the signal quality, i.e. to determine a transmission error by the means for analyzing the signal quality of the at least one data packet, wherein said means are configured to generate the acknowledgement command in case of a sufficiently correct reception of the at least one data packet and/or to generate the non-acknowledgement command in case of an incorrect reception. This acknowledgement command or this non-acknowledgement command is transmitted using the terrestrial signal transmitter, to the terrestrial node in order to initiate using the non-acknowledgement command, a retransmission of the data packet or a redundancy version of the data packet which, for example, may be stored by the terrestrial node. According to a further embodiment, the transceiver of the user equipment comprises a terrestrial signal receiver for receiving the retransmitted data packet or the retransmitted redundancy version of the data packet from the terrestrial node. The uplink of the user equipment may also be realized via the terrestrial node, so that the user equipment comprises a terrestrial signal transmitter to transmit another data packet to be transmitted to the gateway. Vice-versa, where a terrestrial node as well as the satellite are configured to forward another data packet according to further embodiments.

Another aspect refers to a terrestrial node of the system. The base station comprises a non-terrestrial signal receiver, a terrestrial signal receiver, a terrestrial signal transmitter as well as a memory. The non-terrestrial signal receiver is configured to receive a data packet (to retransmit it to the user equipment) or a redundancy version thereof from the satellite of the High Altitude Platform. This data packet or the redundancy version thereof is buffered using the memory. The terrestrial signal receiver serves the purpose to receive the acknowledgement/non-acknowledgement command from the user equipment. The terrestrial signal transmitter is configured to transmit the at least one data packet or redundancy version thereof to the user equipment as a response to the non-acknowledgement command.

According to embodiments, the terrestrial node is configured to listen to the satellite in order to receive the data packet sent to the user equipment. According to another embodiment, the terrestrial node receives the at least one data packet or redundancy version thereof via a separate channel from the non-terrestrial node. According to embodiments, the base station may compress the decoder for performing the decoding of the received data packet received by the non-terrestrial signal receiver in order to generate a redundancy version of the data packet. For example, the decoder may decode and generate the redundancy version for each data packet received by the non-terrestrial signal receiver or perform the decoding and generating on request. According to further embodiments, the decoding may not be performed or suppressed when an information from the user equipment is available, that the received quality is ideal. According to another embodiment, the decoder may just perform the decoding, when the user equipment is assigned with the terrestrial node, and to suppress the decoding, in case a user equipment is not associated with the terrestrial node. The purpose for this is security reasons, such that the buffering of the respective data packets is just performed by the base station/satellite next to the corresponding user equipment.

Another aspect refers to the satellite of the system. Here, the satellite is typically configured to transmit the at least one data packet to the user equipment and in parallel to the base station. Vice-versa, the satellite may be configured to forward the received another data packet to the gateway. According to an embodiment, the satellite may be configured to transmit the at least one data packet to the user equipment and to transmit the at least one data packet or a redundancy version of the data packet to the terrestrial node using a dedicated wideband channel. Here, it is typical, that the HARQ controllers integrated into the gateway controls the transmitter or transmitters of the satellite. The controlling can be performed, in that way, that the gateway assigns different resources for transmitting the at least one data packet to the user equipment and for transmitting the at least one data packet or the redundancy version thereof to the terrestrial node.

Another embodiment assesses the synchronization to a non-terrestrial node, together with a one or more terrestrial Base-station, Buffer or Relay/UE-to-Network-Relay. Here, according to an embodiment, the satellite may comprise a memory for buffering the at least one data packet to be sent to the user equipment or a redundancy version thereof. Here, different buffering strategies may be applied, e.g., if the satellite as well as the terrestrial node comprise buffers. For example, some data packets to be transmitted to the user equipment may be forwarded to the terrestrial node in order to buffer same. For example, different redundancy versions of the at least one data packet (or additional data packets) may be distributed alternating to the memories of the satellite and the terrestrial node. This approach enables to distribute the retransmission balance. According to another approach, the buffering is performed, such that the first redundancy versions are buffered by the memory of the terrestrial node, such that the user equipment has fast access to same, while the last redundancy versions are buffered by the memory of the satellite. Here, the buffering is controlled by the HARQ controller, which may be part of the gateway. According to further embodiments, the buffering is performed based on the satellite downlink congestion level.

Another aspect refers to a terrestrial node comprising a non-terrestrial signal receiver, a memory, a terrestrial signal receiver and a terrestrial signal transmitter. The non-terrestrial signal receiver is configured to receive the data packet or a redundancy version of the data packet from the non-terrestrial node. The memory buffers the data packet or the redundancy version of the data packet. The terrestrial signal receiver receives the information regarding the channel quality of the non-terrestrial channel from the user equipment, wherein the terrestrial signal transmitter retransmits the data packet or a redundancy version of the data packet to the user equipment as response to a channel quality of the non-terrestrial channel below a threshold.

Another aspect refers to terrestrial node comprising a non-terrestrial signal receiver, means for analyzing the signal quality and a terrestrial signal transmitter. The non-terrestrial signal receiver is configured to receive another data packet from the user equipment, the other data packet is to be transmitted to the gateway. The means for analyzing the signal quality of the other data packet are configured to generate an acknowledgement command in case of a sufficiently correct reception of the data packet or to generate an non-acknowledgement command in case of an incorrect reception of the data packet. The terrestrial signal transmitter transmits the acknowledgement command or the non-acknowledgement command to the user equipment in order to initiate using the non-acknowledgement command a retransmission of the other data packet and/or a redundancy version of the other data packet. Here, parallel resources are used for the retransmission. This enables that the forwarding the UL may be continued without interruption although there are some failed frames within the transmission.

All the above aspects are based on the general idea of using satellite connections together with terrestrial networks for a purpose of offloading busy ground base stations and/or covering weak and heavily faded cells. For this reason, the satellite links to the user equipment can be best utilized for downlink (forward) transmission. The uplink channel (during feedback of acknowledgements, channels data information or low traffic uplink data) can be rerouted to the newest possible base station or a network-connected relaying node. The above embodiments minimize the HARQ process timing, delays (including system and frame delivery latency), and overhead over the satellite channel. This is done by utilizing dual-connectivity (DC)/multi-connectivity (MC) with a ground station. Embodiments also offloads the DL traffic from terrestrial to the non-terrestrial network allowing minimum feedback and HARQ mechanism timing.

Although, the above embodiments/aspects have been discussed in context of different entities of the system which is used, it should be noted that further embodiments refer to the corresponding operation methods for operating the user equipment, for operating the terrestrial node, for operating the satellite or for operating the HARQ controller. According to another embodiment the method may be performed using a computer program running on a computer.

Another embodiment provides a system comprising the above-discussed entities.

