Feedback and Channel State Information (CSI) Request Actions

Abstract

[Solution] A receiving device is provided, comprising a control section and a payload section, the control section configured to receive from a transmitting device a data packet including a feedback request indication, the receiving device configured to detect the feedback request indication, attempt to decode the payload section of the data packet, send an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is required for the data packet, and process the data packet without sending an acknowledgement if the feedback request indication indicates that an acknowledgement is not required for the data packet.

Description

[Technical Field]

[0001] The present invention relates to feedback in communication systems. [Background technology]

[0002] A common problem in wireless communications between two devices (e.g., a base station and a user device) is detecting and correcting errors in transmitted data due to, for example, interference or fading in the physical communications channel between the two devices.

[0003] Some wireless protocols use hybrid automatic repeat request (HARQ) techniques to detect and correct errors, in which the receiving device provides feedback to the transmitting device indicating whether a data packet has been successfully (or can be) decoded. HARQ feedback consists of an acknowledgement (ACK) if the decoding is successful or expected to be successful, and a negative acknowledgement (NACK) if the decoding is unsuccessful or expected to be unsuccessful. A negative acknowledgement triggers the transmitting device to retransmit the data. In NB-IoT communication protocols, the evolved Node B (eNB) can specify the specific OFDM time and frequency resources that the user equipment (UE) should use to provide HARQ feedback.

[0004] The use of acknowledgment signals, such as HARQ feedback, can help ensure reliable communication between two devices. However, having to wait for an acknowledgment can cause congestion on subsequent data packet transmissions. This problem can be particularly problematic when the two communicating devices are far apart, as this increases transmission latency. However, the effects of noise and interference can be particularly severe over long-distance communications, so simply disabling HARQ feedback can require very conservative operation with low data rates. Some devices can handle many HARQ processes in parallel, which can alleviate congestion in some situations, but requires additional resources.

[0005] An improved approach would be desirable. Summary of the Invention

[0006] According to a first aspect of the present invention, there is provided a receiving device comprising a control unit and a payload unit, the control unit configured to receive from a transmitting device a data packet including a feedback request indication, detect the feedback request indication, attempt to decode the payload unit of the data packet, send an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is required for the data packet, and process the data packet without sending an acknowledgement if the feedback request indication indicates that an acknowledgement is not required for the data packet.

[0007] According to a second aspect of the present invention, there is provided a communication system comprising a transmitting device and a receiving device, wherein the transmitting device comprises a control unit and a payload unit, the control unit being configured to transmit a data packet including a feedback request indication to the receiving device, and the receiving device is configured to receive the data packet from the transmitting device, detect the feedback request indication, attempt to decode the payload unit of the data packet, send an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is requested for the data packet, and process the data packet without sending an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is not requested for the data packet.

[0008] According to a third aspect of the present invention, there is provided a method of operating a communications system, the method comprising: a transmitting device transmitting a data packet to a receiving device, the data packet comprising a control section and a payload section, the control section including a feedback request indication; the receiving device receiving the data packet, detecting the feedback request indication, attempting to decode the payload section of the data packet, sending an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is required for the data packet, and processing the data packet without sending an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is not required for the data packet.

[0009] Therefore, those skilled in the art will appreciate that the feedback request indication allows for dynamic requesting of feedback on a packet-by-packet basis, thereby providing a communication system with increased flexibility. For example, the transmitting device may use the feedback request indication to request feedback when transmitting important data packets (e.g., conveying resource control signals) and disable feedback when transmitting unimportant data packets, thereby reducing congestion while still ensuring that important data packets are properly received. In many communication systems, performance can be significantly improved because most of the traffic can be classified as unimportant.

[0010] The receiving device may attempt to decode the entire payload portion of the data packet before sending the acknowledgment. Alternatively, the receiving device may attempt to decode only a portion of the payload portion before acknowledging. In some embodiments, attempting to decode the payload portion may consist of first evaluating one or more error detection portions of the data packet (e.g., one or more parity bits or check bits). If the error detection portion indicates that successful decoding is likely, the receiving device may proceed with attempting to decode the entire data packet. Conversely, if the error detection portion indicates that successful decoding is not likely, the receiving device may skip attempting to decode the entire data packet.

[0011] The receiving device may be configured to send the acknowledgment to the transmitting device if the feedback request indication indicates that the acknowledgment is requested for the data packet and an attempt to decode the payload portion is successful or likely to be successful (i.e., an attempt to decode one or more error detection portions or the entire data packet indicates that the data packet was successfully received). In other words, the acknowledgment may be a positive acknowledgment. In such a case, the transmitting device may interpret the absence of an acknowledgment when an acknowledgment is requested as a negative acknowledgment, indicating that some or all of the packet was not successfully received.

[0012] The receiving device may be configured to send the acknowledgment to the transmitting device if the feedback request indication indicates that an acknowledgment is requested for the data packet and an attempt to decode the payload portion has failed or is likely to fail (i.e., an attempt to decode one or more error detection portions or the entire data packet indicates that the data packet was not successfully received). In other words, the acknowledgment may be a negative acknowledgment. The transmitting device may be configured to retransmit the packet upon a negative acknowledgment.

[0013] The receiving device may be configured to send both positive and negative acknowledgments as appropriate. In one set of embodiments, the receiving device is configured to send a positive acknowledgment to the transmitting device if the feedback request indication indicates that an acknowledgment is required for the data packet and the decoding attempt is successful or likely to be successful, and to send a negative acknowledgment to the transmitting device if the feedback request indication indicates that an acknowledgment is required for the data packet and the decoding attempt is or likely to be unsuccessful.

[0014] The acknowledgment sent by the receiving device may consist of a single acknowledgment bit, for example, the acknowledgment bit having a first state (e.g., "1") may indicate a positive acknowledgment, and the acknowledgment bit having a second state (e.g., "0") may indicate a negative acknowledgment.

[0015] The acknowledgement may comprise a Hybrid Automatic Repeat Request (HARQ) acknowledgement, where a positive acknowledgement may comprise a HARQ-ACK and a negative acknowledgement may comprise a HARQ-NACK.

[0016] In one set of embodiments, the receiving device (and the transmitting device) are configured to communicate using Orthogonal Frequency Division Multiplexing (OFDM). The data packets may be comprised of OFDM packets consisting of multiple symbols spread across multiple time periods and multiple frequency subcarriers. In one set of embodiments, the receiving device is configured to operate in accordance with a 3GPP Long Term Evolution (LTE) communications protocol, such as the Narrowband Internet of Things (NB-loT) protocol.

[0017] The transmitting device and the receiving device may be configured to perform bidirectional communication, i.e., each may comprise a transceiver device. In other words, in one set of embodiments, the transmitting device comprises a first transceiver device and the receiving device comprises a second transceiver device. In such embodiments, the first transceiver device may also be configured to receive and acknowledge data packets from the second transceiver device in a similar manner.

[0018] The transmitting device may be a base station, for example, an LTE-Evolved Node B (eNB), such as an eNB of the NB-IoT standard. The receiving device may be an end user device, for example, an LTE-standard User Equipment (UE), such as an NB-IoT standard UE. The data packets transmitted by the receiving device may be downlink data packets. The acknowledgement may be transmitted in an uplink data packet. Conversely, the receiving device may be a base station, for example, an LTE-Evolved Node B (eNB), and the transmitting device may be an end user device, for example, an LTE-standard User Equipment (UE).

[0019] The transmitter may be configured to wait for an acknowledgment (if requested) for a given data packet before transmitting additional data packets (i.e., in case a retransmission of the data packet is necessary). In some embodiments, the communications system may be configured to support multiple acknowledgment processes in parallel, i.e., acknowledgments for multiple packets can exist simultaneously. However, applicants have come to recognize that supporting multiple parallel acknowledgment processes may require additional hardware resources and increase energy usage. Thus, in one set of embodiments, the receiving device and / or the transmitting device are configured to support only a limited number of parallel acknowledgment processes. For example, the receiving device and / or the transmitting device may be configured to support only one acknowledgment process at a time, or to support only two parallel acknowledgment processes.

[0020] In one set of embodiments, the communications system is a non-terrestrial communications system (i.e., forming part of a non-terrestrial network (NTN)). The transmitting device may be provided, for example, by a satellite in low earth orbit. The receiving device may be a terrestrial device (i.e., located on or near the surface of the Earth) configured to receive data packets from the transmitting device provided by the satellite. For example, the receiving device may be an IoT device of an NTN. The advantages of the present invention may be particularly pronounced in non-terrestrial communications systems where transmission distances (and therefore propagation delays) can be large and congestion problems may be most common (e.g., when the system runs out of acknowledgement procedures to use).

[0021] In one set of embodiments, the control unit is configured as a Physical Downlink Control Channel (PDCCH) of the LTE standard, e.g., a Physical Downlink Control Channel (NPDCCH) of the NB-ioT standard. The feedback request indication may be configured in the ACK / NACK field of DCI format N1. Conventionally, the ACK / NACK resource field simply indicates which resources to use for HARQ feedback, but the applicant has realized that it may be beneficial to reuse this to provide dynamic feedback operation.

[0022] The acknowledgement (positive or negative) may be transmitted as part of a subsequent data packet transmitted from the receiving device to the transmitting device. For example, the acknowledgement may be transmitted as part of Uplink Control Information (UCI) on a Physical Uplink Control Channel (PUCCH) or a Physical Uplink Shared Channel (PUSCH) of the LTE standard, e.g., a Physical Uplink Control Channel (NPUCCH) or a Physical Uplink Shared Channel (NPUSCH) of the NB-IoT standard. In one set of embodiments, the acknowledgement is transmitted using Physical Uplink Shared Channel (NPUSCH) Format 2 of the NB-IoT standard.

[0023] The acknowledgment (positive or negative) may be transmitted using fixed (i.e., predetermined) time and frequency resources (e.g., at a predetermined time and frequency offset within an OFDM packet structure). However, in one set of embodiments, the feedback request indication specifies the time and / or frequency resources on which the acknowledgment is to be transmitted. For example, the feedback request indication may indicate a frequency and / or time offset within an OFDM packet structure on which the acknowledgment should be transmitted. The feedback request indication may specify a subcarrier and / or a time slot on which the acknowledgment (e.g., an uplink control signal carrying an ACK / NACK message) is to be transmitted. Enabling dynamic allocation of time and / or frequency resources for the acknowledgment may improve flexibility and performance of the communications system. In some embodiments, the feedback request indication may be configured to only specify time and / or frequency resources, and the receiving device is configured to interpret a range of time and / or frequency resources (e.g., a single time and / or frequency resource) specified in the feedback request indication as indicating that feedback is not requested. This allows existing control signals, such as the ACK / NACK resource field, to be reused for conveying additional acknowledgement control signals without requiring major changes on the sending side, making it easy to apply the present invention to each existing communication protocol.

[0024] As explained above, allowing the transmitting device to dynamically request packet acknowledgments provides increased flexibility and reduces communication congestion caused by long round-trip acknowledgment latencies. However, because not all packets are acknowledged, the communication system may be more vulnerable to data loss due to poor communication channel conditions. In some embodiments, feedback may be requested for only a small portion of each packet (e.g., less than 10% of each packet). Accordingly, in one set of embodiments, the receiving device is configured to determine channel quality information regarding a communication channel between the transmitting device and the receiving device, and, if the feedback request indication indicates that channel quality information is requested, transmit the channel quality information to the transmitting device.

[0025] Thus, the transmitting device can dynamically request and receive updates regarding channel conditions. This allows the transmitting device to identify when channel conditions are deteriorating and take appropriate action (e.g., requesting packet feedback more frequently). The transmitting device may be configured to perform additional error correction in response to channel quality information transmitted from the receiving device, for example, by reducing the coding rate of data packets. For example, if the channel quality information indicates that channel conditions have deteriorated or are deteriorating, the transmitting device may be configured to request feedback for the next data packet using the feedback request indication. For example, the transmitting device (or a corresponding network system) may classify the receiving device as a mobile device based on the channel quality information and previous communications.

[0026] The receiving device may be configured to determine the channel quality information by measuring the signal-to-noise ratio (SNR) of a received signal (e.g., a common downlink signal such as a narrowband reference signal (NRS) or a synchronization signal).

[0027] The channel quality information may comprise a variety of different indications of channel quality. The channel quality information may comprise an absolute indication or measurement of channel quality, such as a value indicating channel quality on a numerical scale. For example, the channel quality information may comprise the SNR of the received signal. Additionally or alternatively, the channel quality information may comprise a relative or differential indication or measurement of channel quality, such as channel quality compared to a previous report on channel quality, or a trend in channel quality (e.g., indicating whether channel quality is improving or worsening). The channel quality information may, for example, identify whether the SNR of the received signal is increasing or decreasing, and optionally indicate the degree of this increase or decrease. The channel quality information may comprise a Channel State Information (CSI) report of the LTE standard.

[0028] The channel quality information may consist of a single bit, for example, a bit having a first state (e.g., "1") may indicate "good" or "improving" channel quality, and a bit having a second state (e.g., "0") may indicate "bad" or "deteriorating" channel quality.

[0029] Alternatively, in one set of embodiments, the channel quality information may comprise multiple bits, e.g., providing more detailed information about the quality of the communication channel. The channel quality information may comprise multiple bits coded using an orthogonal cover code (OCC), e.g., coded with a predetermined bit or symbol sequence that is transmitted to the transmitting device. For example, an OCC may be used to code two bits with a predetermined bit or symbol sequence that carries uplink control information (e.g., uplink control channel symbols).

[0030] Similar to the acknowledgement, the channel quality information may be transmitted as part of a subsequent data packet transmitted from the receiving device to the transmitting device. It may be transmitted using fixed (i.e., predetermined) time and frequency resources (e.g., at a predetermined time and frequency offset within an OFDM packet structure). However, in one set of embodiments, the feedback request indication specifies the time and / or frequency resources on which the channel quality information is to be transmitted. For example, the feedback request indication may indicate a frequency and / or time offset within an OFDM packet structure from which the channel quality information should be transmitted. The feedback request indication may specify subcarriers and / or time slots on which the channel quality information (e.g., an uplink control signal carrying the channel quality information) is to be transmitted. Enabling dynamic allocation of time and / or frequency resources for the channel quality information may improve the flexibility and performance of the communication system.

[0031] The receiving device may be configured to transmit the aforementioned channel quality information along with the acknowledgement. For example, the feedback request indication may indicate that channel quality information and an acknowledgement are requested for the data packet. The feedback request indication may indicate that one or both of the channel quality information and the acknowledgement are requested, or that neither is requested. In other words, for some packets, the transmitting device may request either no feedback (no acknowledgement or channel quality information), an acknowledgement but no channel quality information, channel quality information but no acknowledgement, or an acknowledgement and channel quality information (i.e., maximum feedback).

[0032] The receiving device may be configured to combine the channel quality information and the acknowledgment, e.g., to improve communication efficiency. For example, the receiving device may be configured to encode the channel quality information and the acknowledgment as a single transmission signal. In one set of embodiments, the receiving device may be configured to encode the channel quality information using time and / or frequency resources used to transmit the acknowledgment (e.g., to encode the channel quality information using at least two time and / or frequency resources available for transmitting the acknowledgment). Accordingly, the transmitter may be configured to encode the channel quality information by detecting which time and / or frequency resources the acknowledgment is transmitted on (e.g., which subcarriers and / or time slots the acknowledgment is transmitted on). For example, the receiving device may be configured to transmit the acknowledgment using one or more specific time and / or frequency resources that identify the channel quality information. In other words, the receiving device may be configured to select time and / or frequency resources to use for the acknowledgment based on channel quality. The transmitting device may be configured to perform blind decoding within a set of time and / or frequency resources (e.g., a set specified by the transmitting device using the feedback request indication) to detect the acknowledgment and / or decode channel quality information.

[0033] In one set of embodiments, the receiving device may be configured to transmit the acknowledgment using a first set of time and / or frequency resources indicative of a first channel quality indication and to transmit the acknowledgment using a second set of time and / or frequency resources indicative of a second channel quality indication. For example, the feedback request indication may indicate that an acknowledgment and channel quality information are requested and may specify a pair of time and / or frequency resources to use when transmitting the acknowledgment and the channel quality information. As a result, the receiver may be configured to transmit the acknowledgment using a first pair of resources indicative of a first channel quality (e.g., indicating that channel quality is improving) and a second pair of resources indicative of a second channel quality (e.g., indicating that channel quality is deteriorating). In other words, the receiving device may be configured to convey channel quality information to the transmitting device by transmitting an acknowledgment (e.g., HARQ-ACK / NACK feedback) using specific resources.

[0034] Each feature of any aspect or embodiment described herein may, where appropriate, also apply to any other aspect or embodiment described herein, and where reference is made to different embodiments, it should be understood that these are not necessarily entirely different and may overlap. [Brief explanation of the drawings]

[0035] One or more embodiments will now be described, by way of example only and not by way of limitation, with reference to the accompanying drawings, in which: [Figure 1] 1 is a schematic diagram of a wireless communication system according to an embodiment of the present invention; [Figure 2] 1 illustrates a downlink data packet used in each embodiment of the present invention. [Figure 3] 1 illustrates an uplink data packet used in each embodiment of the present invention. [Figure 4] 10 illustrates the information provided in a feedback request prompt of one embodiment of the present invention. [Figure 5] 10 illustrates information provided in a feedback request instruction field according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] 1 illustrates a wireless communication system 100 operating according to an NB-IoT communication protocol. The system 100 comprises an evolved Node B (eNB) 102 and a user equipment (UE) 104. In this example, the communication system 100 forms part of a non-terrestrial network (NTN), where the eNB 102 is served by a satellite (e.g., a low-earth orbit satellite) and the UE 104 is an IoT device of the terrestrial NTN (e.g., a sensor device at or near the Earth's surface).

[0037] In use, the eNB 102 transmits data to the UE 104 using downlink data packets on the physical channel, and the UE 104 transmits data to the eNB 102 using uplink data packets on the physical channel. The downlink and uplink data are transmitted using OFDM across 12 subcarriers at 3.75 kHz or 15 kHz, respectively.

[0038] An example of a downlink data packet 200 is shown schematically in Figure 2. The downlink packet 200 consists of a control portion allocated to a NB-IoT standard Physical Downlink Control Channel (NPDCCH) 202 (packet 200 may consist of multiple portions allocated to the NPDCCH, but only one is shown here). The NPDCCH 202 carries downlink control information (DCI), such as resource allocation and decoding information. The downlink data packet 200 also includes a payload portion (again, only one portion is shown) allocated to a NB-IoT standard Physical Downlink Shared Channel (NPDSCH) 204. The NPDCCH 204 carries the actual user data.

[0039] An example of an uplink data packet 300 is shown in Figure 3. The uplink data packet 300 consists of a control section (one example shown) assigned to the NB-ioT standard Physical Uplink Shared Channel (NPUSCH) Format 2 302. The NPUSCH Format 2 302 carries Uplink Control Information (UCI).

[0040] The radio signals carrying downlink data packets 200 from the eNB 102 to the UE 104 may be subject to noise, interference, and fading. Therefore, the communication system 100 employs a dynamic hybrid automatic repeat request (HARQ) technique that allows the UE 104 to send feedback to the eNB 102 indicating that a packet arrived correctly or requesting that the eNB 102 retransmit an incorrectly received packet. However, because the eNB 102 is provided by satellite, the physical distance between the eNB 102 and the UE 104 can be large (e.g., hundreds of kilometers), resulting in relatively long round-trip signal times. The need to wait for HARQ feedback for each packet can lead to communication congestion if the transmitter runs out of HARQ processes to schedule (and, in some embodiments, may only have one HARQ process available).

[0041] Therefore, the communication system 100 uses a dynamic HARQ feedback scheme in which feedback is not sent on a packet-by-packet basis. The NPDCCH 202 of each downlink data packet 200 includes a feedback request indication field 206 that indicates to the UE 104 whether feedback is requested for that data packet 200, and the time-frequency resources 304 in the NPUSCH format 2 302 of the uplink data packet 300 that are used for this feedback.

[0042] The communications system 100 can also facilitate providing periodic channel state information (CSI) updates from the UE 104, i.e., periodic reporting on the quality of the channel between the eNB 102 and the UE 104. A feedback request indication field 206 in each downlink data packet 200 indicates whether a CSI update is requested and which resources in the NPUSCH format 2 302 of the uplink data packet 300 to use for this update. It is particularly useful for the eNB 102 to be able to request periodic CSI updates when HARQ feedback is not used periodically, and to identify when channel conditions are deteriorating and when additional error compensation (e.g., increasing the periodic request for HARQ feedback or changing the coding rate for future data packets) may be necessary.

[0043] Dynamic feedback can be implemented in various ways. Two possible embodiments are now described with further reference to Figures 4 and 5. In these embodiments, the feedback request indication field 206 is the ACK / NACK resource field of DCI format N1. The feedback request indication field 206 consists of 4 bits (i.e., it can have 16 values). When HARQ feedback is requested, the UE 104 sends a single-bit acknowledgment indicating whether the packet was received correctly (ACK) or not (NACK).

[0044] In one embodiment (shown in FIG. 4), the feedback request indication field 206 can a) indicate that HARQ feedback is requested and specify one of eight resources in NPUSCH format 2 302 to be used for HARQ feedback, b) indicate that a CSI update is requested and specify one of seven resources for CSI information in NPUSCH format 2 302, or c) indicate that feedback is not requested.

[0045] If the feedback request indicator field 206 has a value in the first set 402, it indicates that HARQ-ACK / NACK feedback is requested (option (a)). The first set 402 has eight possible values ​​(0, 1, 4, 5, 8, 9, 12, and 13), which specify eight possible resources for HARQ feedback in NPUSCH format 2 302. For example, a value of "0" indicates that the HARQ feedback bit (ACK / NACK) should be transmitted on subcarrier index 0 in NPUSCH format 2 302 of the uplink data packet 300 with a timing offset of k0=13.

[0046] If the feedback request indication field 206 has a value in the second set 404, it indicates that no HARQ-ACK / NACK is requested but a CSI update is requested (option (b)). The second set 404 has seven candidate values ​​(2, 3, 6, 7, 10, 11, and 14), which specify seven candidate resources for the CSI report in the NPUSCH format 2 302. For example, a value of "2" indicates that the CSI report data should be transmitted on subcarrier index 2 in the NPUSCH format 2 302 of the uplink data packet 300 with a timing offset of k0=13.

[0047] Finally, if the feedback request instruction field 206 has a value in the third set 406, this indicates that feedback is not requested (i.e., option ((c)). In this example, the third set 406 consists of a single value, "15."

[0048] In use, the UE 104 receives downlink data packets, detects the value of the feedback request indicator field 206, and attempts to decode the user data carried in the NPDSCH 204. In the first step of this decoding, the UE 104 evaluates one or more error detection portions of the downlink data packet (e.g., one or more check bits or parity bits), which indicate whether the data packet is sufficiently error-free for its decoding to be successful.

[0049] If the value of the feedback request indication field 206 is in the first set 402, the UE 104 transmits an ACK or NACK to the eNB 102 using the resources indicated by the value of the feedback request indication field 206 in NPUSCH format 2 302. If the decoding attempt is successful, the UE 104 transmits an ACK (e.g., "1"), and if the decoding attempt is unsuccessful, the UE 104 transmits a NACK (e.g., "0").

[0050] If the value of the feedback request indication field 206 is in the second set 404, the UE 104 does not send an ACK or NACK, but sends a CSI indication based on recent measurements of channel quality to the eNB 102 using the resources indicated by the value of the feedback request indication field 206 in NPUSCH format 2 302. The CSI indication is determined, for example, from channel quality measurements based on narrowband reference signals or synchronization signals received by the receiver.

[0051] If the value of the feedback request indication field 206 is in the third set 406 (ie, equal to "15"), the UE 104 does not send any feedback to the eNB 102 and simply continues processing the downlink data packet.

[0052] In another embodiment (shown in FIG. 5), the UE 104 returns HARQ-ACK / NACK feedback and CSI information together. The feedback request indication field 206 is again a 4-bit field that can assume 16 values. In this embodiment, the feedback request indication field 206 can a) indicate that HARQ feedback is requested and specify one of the eight pairs of resources for HARQ-ACK / NACK and CSI update combinations in NPUSCH format 2 302, or b) indicate that feedback is not requested.

[0053] The least significant bit (LSB) of the feedback request indication field 206 indicates whether feedback is requested. If the LSB is equal to 1 (i.e., the value of the feedback request indication field 206 is odd), the UE 104 is instructed to not send feedback (i.e., not to send HARQ-ACK / NACK feedback or CSI reports).

[0054] If the LSB is equal to 0 (i.e., the value of the Feedback Request Indicator field 206 is even or 0), the UE 104 is instructed to return HARQ feedback and CSI updates. The remaining 3 bits are used to specify how this feedback should be sent.

[0055] The remaining three bits identify which of the eight pairs of resources in NPUSCH format 2 302 is used for HARQ-ACK / NACK and CSI feedback (if feedback is enabled). For example, if the remaining three bits are all equal to zero, this identifies the first resource pair 500 in NPUSCH format 2 302 of uplink data packet 300, which consists of a first resource 502 with subcarrier index 0 and a timing offset of k0=13, and a second resource 504 with subcarrier index 1 and a timing offset of k0=13.

[0056] The UE 104 transmits a combination of HARQ-ACK / NACK and CSI feedback by transmitting HARQ feedback (e.g., "0" or "1") on a designated resource pair corresponding to the desired CSI report. If channel quality is improving, the UE 104 transmits HARQ feedback on the first resource 502 of the pair. If channel quality is deteriorating, the UE 104 transmits HARQ feedback on the second resource 504 of the pair. The eNB 102 then performs blind decoding at the appropriate position within NPUSCH format 2 302 to identify which resource 502, 504 was used (to identify the CSI report) and determine the bits transmitted on that resource (to identify the HARQ feedback). Encoding the CSI feedback using the time and frequency resources used for transmitting the HARQ-ACK / NAK allows for particularly flexible use of communication resources, as the UE may transmit two bits while transmitting on only a single resource. In this embodiment, the amount of uplink (UL) resources used for UE feedback increases (i.e., two subcarriers are reserved for one UE), but due to the fact that feedback may be disabled for most downlink data packets, the overall use of UL control resources in the network may not increase.

[0057] In the embodiment shown in FIG. 5, the ACK / NACK is combined with another indication of whether the channel quality is improving or deteriorating. In a variation of this embodiment, the ACK / NACK itself can also be used to indicate CSI information. For example, as shown in Table 1 below, an ACK transmitted on the first resource may indicate an SNR increase of 0.5 dB, and a NACK transmitted on the first resource may indicate an SNR decrease of −0.5 dB. An ACK transmitted on the second resource may indicate a larger SNR increase of 2 dB, and a NACK transmitted on the second resource may indicate an even larger SNR decrease of −2 dB. The CSI information indicated by ACK / NACK on the same resource is not necessarily symmetrical (e.g., an ACK on the first TF resource may indicate no change in SNR, and a NACK on the first TF resource may indicate a change in SNR of −0.5 dB). TIFF2025529667000002.tif28166Table 1 - Using ACK / NACK to indicate CSI information

[0058] While the present invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions, or equivalent arrangements not heretofore described, but which are commensurate with the scope of the invention. Also, while various embodiments of the invention have been described, it should be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the present invention is not limited by the foregoing description, but is limited only by the appended claims.

Claims

1. a control unit and a payload unit, the control unit receiving a data packet including a feedback request instruction from a transmitting device; Detecting a feedback request indication; attempting to decode a payload portion of said data packet; transmitting an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is required for the data packet; and processing the data packet without sending an acknowledgement if the feedback request indication indicates that no acknowledgement is required for the data packet. A receiving device characterized by:

2. configured to transmit an acknowledgment to the transmitting device if the feedback request indication indicates that an acknowledgment is requested for the data packet and an attempt to decode the payload portion is successful or expected to be successful.

2. The receiving device according to claim 1, wherein:

3. configured to transmit a negative acknowledgment to the transmitting device if the feedback request indication indicates that an acknowledgment is required for the data packet and an attempt to decode the payload portion fails or is likely to fail.

3. The receiving device according to claim 1 or 2.

4. The acknowledgement comprises an acknowledgement of a hybrid automatic repeat request.

4. The receiving device according to claim 1, wherein the receiving device is a receiving device for receiving a signal from a receiving terminal.

5. comprising a ground device configured to receive data packets from a transmitter provided by a satellite.

5. The receiving device according to claim 1, wherein the receiving device is a receiving device for receiving a signal from a receiving terminal.

6. The data packet comprises an orthogonal frequency division multiplexed packet comprised of multiple symbols spread across multiple time periods and multiple frequency subcarriers.

6. The receiving device according to claim 1, wherein the receiving device is a receiving device for receiving a signal from a receiving terminal.

7. Consists of user equipment that conforms to the LTE NB-IoT standard 7. The receiving device according to claim 6, wherein:

8. The control unit is configured in a physical downlink control channel of the LTE standard, and the feedback request indication is configured in the ACK / NACK field of DCI format N1.

8. The receiving device according to claim 6 or 7.

9. The feedback request indication specifies time and / or frequency resources for transmitting the acknowledgement.

9. The receiving device according to claim 1, wherein the receiving device is a receiving device for receiving a signal from a receiving terminal.

10. The receiving device is configured to interpret the range of time and / or frequency resources specified in the feedback request indication as an indication that feedback is not requested.

10. The receiving device according to claim 9, wherein:

11. determining channel quality information relating to a communication channel between the transmitting device and the receiving device; and transmitting the channel quality information to the transmitting device if the feedback request indication indicates that channel quality information is requested.

11. A receiving device according to claim 1, wherein the receiving device is a receiving device for receiving a signal from a receiving terminal.

12. The channel quality information is comprised of a plurality of bits coded with a predetermined bit or sequence of symbols that are transmitted to the transmitter using an orthogonal cover code.

12. The receiving device according to claim 11, wherein:

13. The feedback request indication specifies time and / or frequency resources for transmitting the channel quality information.

13. The receiving device according to claim 11 or 12.

14. The receiving device is configured to encode the channel quality information using time and / or frequency resources used to transmit the acknowledgement.

14. A receiving device according to claim 11, wherein the receiving device is a receiving device for receiving a signal from a receiving terminal.

15. configured to transmit the acknowledgement using a first set of time and / or frequency resources indicative of a first channel quality indication, and to transmit the acknowledgement using a second set of time and / or frequency resources indicative of a second channel quality indication.

15. The receiving device according to claim 14, wherein:

16. a transmitting device; a receiving device, the transmitting device is configured to include a control unit and a payload unit, and the control unit is configured to transmit a data packet including a feedback request instruction to the receiving device; The receiving device receiving the data packet from the transmitting device; detecting the feedback request indication; attempting to decode a payload portion of said data packet; transmitting an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is required for the data packet; and processing the data packet without sending an acknowledgement to the transmitting device if the feedback request indication indicates that no acknowledgement is required for the data packet. A communication system comprising:

17. 1. A method of operating a communications system, the method comprising: a transmitting device configured with a control unit and a payload unit, the control unit transmitting a data packet including a feedback request instruction to a receiving device; The receiving device: receiving the data packet; detecting the feedback request indication; attempting to decode a payload portion of said data packet; transmitting an acknowledgement to the transmitting device if the feedback request indication indicates that an acknowledgement is required for the data packet; and processing the data packet without sending an acknowledgement to the transmitting device if the feedback request indication indicates that no acknowledgement is required for the data packet. A method characterized by:

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