1-bit signaling feedback to configure or change the communication system device

Abstract

The present application discloses a device for configuring or changing a communication system by 1-bit signaling feedback. In the communication system, a transmitter is configured to change a transmission feature used for communicating with a receiver, wherein the receiver is configured to determine the reception quality of a communication link between the transmitter and the receiver, and send feedback information indicating whether the reception quality has changed or the direction of the reception quality change or whether the transmission feature should be maintained to the transmitter, wherein the transmitter is configured to further change the transmission feature used for communicating with the receiver depending on the feedback information received from the receiver.

Description

[0001] This application is a divisional application whose applicant is Fraunhofer Gesellschaft, whose application date is June 13, 2017, whose application number is 201780050292.1, and whose invention name is “Device for configuring or changing a communication system with 1-bit signaling feedback”. Technical Field

[0002] Embodiments relate to transmitters and receivers. Other embodiments relate to methods for transmitting and methods for receiving. Some embodiments relate to 1-bit signaling feedback to configure or change settings of a communication system. Some embodiments relate to 1-bit signaling feedback to improve the performance of full-dimensional MIMO. Background Art

[0003] In any communication system consisting of a transmitter and a receiver communicating over a noisy channel, resources are required, where the configuration of the system is obtained by feedback from the receiver to the transmitter. Figure 1 A schematic block diagram of such a communication system 100 is shown comprising a transmitter 12 and a receiver 14 communicating on a channel 11 that overlaps with noise 13. Whenever the set of possible configurations becomes larger, the feedback 30 for selecting a particular configuration also becomes larger. Thus, a limited feedback channel 30 also limits the number of possible configurations to choose from.

[0004] The communication system may be a wired communication system like the Internet or a wireless communication system like WLAN (WLAN=Wireless Local Area Network), GSM (GSM=Global System for Mobile Communications), UMTS (UMTS=Universal Mobile Telecommunications System) and LTE (LTE=Long Term Evolution).

[0005] The settings of the communication system that may be changed or configured using the feedback channel 30 may be the modulation and / or code rate selected therefrom, the set of transmitters and combinations thereof, in a wireless system with multiple antenna transmitters, the number of beamformers / precoders, and in a wireless system with resource pools, for example in the frequency domain, the spatial domain, or the code domain.

[0006] In the recently completed LTE Release 12, up to 8 antennas and multiplexing streams are considered. For example, in the study called "Study on Elevation Beamforming / Full-Dimension (FD) MIMO for LTE" [3GPP, "Study on Elevation Beamforming / Full-Dimension (FD) MIMO for LTE", 3rd Generation Partnership Project, Volume 13.0.0, July 2015], the trend towards more antennas and therefore increasing the total spectral efficiency by multiplexing more streams continues, with up to 64 antennas and 16 streams considered. Amplifying the existing mechanisms of LTE leads to an increase in overhead and signaling in the downlink due to the insertion of reference signals (RS) and channel state information reference signals (CSI-RS) in the physical downlink shared channel (PDSCH). In Figure 2 The main signal flows of precoded downlink MIMO in a frequency division duplex (FDD) system are shown in FIG.

[0007] Figure 2 Shown in [Li, J., Su, X., Zeng, J., Zhao, Y., Yu, S., Xiao, L., and Xu, X. (2013, June). Codebook design for uniform rectangular arrays of massive antennas. Vehicular Technology Conference (VTC Spring) , 2013 IEEE 77 (pp. 1-5), IEEE] for signal flow in downlink MIMO FDD systems with precoding. Specifically, Figure 2 1 shows a schematic block diagram of a MIMO system 10 including a multi-antenna transmitter 12 and a multi-antenna receiver 14. The multi-antenna transmitter 12 includes a precoder (precoding unit) 16 and a plurality of antennas 18 (eg, N antennas) connected to the precoder 16. t antennas, where N t is a natural number greater than or equal to 2, N t ≥2). The multi-antenna receiver 14 includes a demodulator (or demodulation unit) 20 and a plurality of antennas 22 (eg, N r antennas, where N r is a natural number greater than or equal to 2, N r ≥2). In addition, the multi-antenna receiver 14 includes a CSI extractor 24 (CSI=channel state information), a codebook 26 and a codeword selector 28. The CSI extractor 24 is configured to extract channel state information. The codebook 26 includes a plurality of codewords. Each codeword may be associated with a codebook index. The codeword selector is configured to select one of the codewords of the codebook based on the channel state information provided by the CSI extractor 24. The multi-antenna receiver 14 is configured to send the codebook index of the selected codeword to the multi-antenna transmitter 12 using uplink feedback 30. The multi-antenna transmitter 12 also includes a codebook 32, which includes a plurality of codewords, wherein the codebook 32 is configured to select one of the codewords based on the codebook index received from the multi-antenna receiver 14 on the uplink feedback 30 and provide the selected codeword to the precoder 16.

[0008] The codebook size at the receiver and hence the codeword selection is limited due to the insertion of SR and CSI-RS in the PDSCH. It is known from the literature that the limited codebook of the beamformer / precoder (used interchangeably in this document) also limits the performance through beamforming gain. The codebook is a quantization of the channel and results in a mismatch (loss of beamforming gain) compared to precoding with perfect channel state information (CSI) at the transmitter [D. Love, R. Heath, V. Lau, D.Gesbert, B. Rao and M. Andrews, “An overview of limited feedback in wirelesscommunication systems”, Selected Areas in Communications, IEEE Journal on, Volume 26, Pages 1341-1365, October 2008].

[0009] With [3GPP, “Study on Elevation Beamforming / Full-Dimension (FD) MIMOfor LTE”, 3rd Generation Partnership Project , Volume V13.0.0, July 2015], the simulation assumptions are similar, Figure 3 The possible gain from increasing the codebook size is given in . Specifically, Figure 3 Figure 1 shows the SINR (signal to interference plus noise ratio) from increasing codebook size in a full-dimensional MIMO downlink transmission, compared to LTE Release 13 [3GPP, “Study on Elevation Beamforming / Full-Dimension (FD) MIMO for LTE”, 3rd Generation Partnership Project , Volume V13.0.0, July 2015] have similar assumptions. Figure 3 In , approximately 10 dB gain in SINR from 16 to 200 beamformers can be observed. Therefore, it may be desirable to have a larger codebook without additional signaling overhead to increase spectral efficiency through increased beamforming gain.

[0010] In the research project “Study on Elevation Beamforming / Full-Dimension (FD) MIMO for LTE” [3GPP, “Study on Elevation Beamforming / Full-Dimension (FD) MIMO for LTE”, 3rd Generation Partnership Project, Volume V13.0.0, July 2015], the problem is addressed by directly increasing the amount of reference signals (RS) and channel state information reference signals (CSI-RS) in the physical downlink shared channel (PDSCH). There is a trade-off between reduced efficiency of the PDSCH and the gain from spatial multiplexing of a larger number of streams. Even by limiting the number of streams, for example to 16, there is still the gain expected from an increased codebook size or a higher quantization of the CSI.

[0011] US2015 / 0016560A1 discloses a system and method for feedback in a precoded MIMO communication system. Specifically, in a closed-loop wireless communication system, a codebook-based feedback mechanism is provided to enable non-uniform precoding for multi-stream transmission, wherein suitable transmit power allocation and AMC are used in each stream for optimization. The codebook-based feedback mechanism uses a precoding codebook with a power allocation matrix, which is constrained to specify that beamforming always applies full power to a predetermined beam. With this constraint, a 1-bit power allocation feedback index can be used to switch between beamforming and spatial multiplexing. Summary of the invention

[0012] It is therefore an object of the present invention to provide a concept that allows increasing the number of different possible configurations of a communication system to choose from, without increasing the configuration selection signalling overhead.

[0013] An embodiment provides a transmitter for communicating with a receiver, wherein the transmitter is configured to change a transmission characteristic for communicating with the receiver, wherein the transmitter is configured to further change the transmission characteristic for communicating with the receiver depending on feedback information received from the receiver, the feedback information indicating whether the reception quality has changed or the direction of the reception quality change or whether the transmission characteristic should be maintained.

[0014] Other embodiments provide a receiver configured to establish a communication link with a transmitter, wherein the receiver is configured to determine a reception quality of the communication link, wherein the receiver is configured to send feedback information to the transmitter indicating whether the reception quality has changed or the direction of the change in reception quality or whether the transmission characteristic should be maintained.

[0015] According to the concept of the present invention, feedback information (e.g., 1-bit feedback information) sent from a receiver to a transmitter is used to indicate to the transmitter whether the reception quality has changed or the direction of the reception quality change or whether the transmission characteristics should be maintained. Based on the feedback information, the transmitter can adjust its transmission characteristics for communicating with the receiver.

[0016] Other embodiments provide a method for sending, the method comprising:

[0017] - Establishing a communication link with a receiver;

[0018] - changing the transmission characteristics used to communicate with the receiver; and

[0019] - further changing the transmission characteristics used for communicating with the receiver depending on feedback information received from the receiver, the feedback information indicating whether the reception quality has changed or the direction in which the reception quality has changed or whether the transmission characteristics should be maintained.

[0020] Other embodiments provide a method for receiving, the method comprising:

[0021] - Establish a communication link with the transmitter;

[0022] - determining the reception quality of the communication link; and

[0023] - Sending feedback information to the transmitter indicating whether the reception quality has changed or the direction in which the reception quality has changed or whether the transmission feature should be maintained.

[0024] In an embodiment, the feedback information may include exactly 1 bit.

[0025] When the value of the reception quality detected by the receiver is greater than a reference value, the feedback information may include a first value, and when the value of the reception quality detected by the receiver is equal to or less than the reference value, the feedback information may include a second value different from the first value. The reference value may be a previous value of the reception quality or a minimum value or a maximum value among a plurality of previous values ​​of the reception quality.

[0026] When the value of the reception quality detected by the receiver is less than a reference value, the feedback information may include a first value, and when the value of the reception quality detected by the receiver is equal to or greater than the reference value, the feedback information may include a second value different from the first value. The reference value may be a previous value of the reception quality or a minimum value or a maximum value among a plurality of previous values ​​of the reception quality.

[0027] In an embodiment, the reception quality may be at least one of a signal to interference plus noise ratio, a signal to noise ratio, a channel quality indicator, a received signal power, and an effective data throughput.

[0028] In an embodiment, the transmission characteristic may be at least one of a transmission power, a code rate, a set of scheduled resources, a beamforming pattern, a precoder setting, and a set of access nodes for coordinated transmission in a single frequency network.

[0029] In an embodiment, in the first operating mode, the transmitter may be configured to select one from a plurality of different transmission characteristics for communicating with the receiver depending on selection information received from the receiver.

[0030] In an embodiment, in the first mode of operation, the transmitter may be configured to randomly select one of a plurality of different transmission characteristics for communicating with the receiver.

[0031] In an embodiment, in the first operating mode, the transmitter may be configured to select a default transmission feature.

[0032] In an embodiment, in the second operation mode, the transmitter may be configured to change transmission characteristics for communicating with the receiver, wherein the transmitter may be configured to further change the transmission characteristics for communicating with the receiver depending on feedback information received from the receiver.

[0033] The transmitter may be configured to switch to a first operating mode for establishing a communication link between the transmitter and the receiver.Furthermore, the transmitter may be configured to switch to a second mode for a time period comprising at least two changes in the transmission characteristics.

[0034] The transmitter may be configured to signal a change of the operating mode to the receiver.Alternatively, the transmitter may be configured to change the operating mode in dependence on signaling information received from the receiver.

[0035] The transmitter may be configured to not use a downlink channel from the transmitter to the receiver in the second operation mode for transmitting control information (eg reference signals, pilots), the control information indicating to the receiver the transmission characteristics to use.

[0036] In an embodiment, the transmitter may be configured to iteratively further vary transmission characteristics used for communicating with the receiver depending on feedback information received from the receiver.

[0037] In an embodiment, the transmitter may comprise a plurality of antennas, wherein the transmission characteristic may be a beam pattern, wherein the transmitter may be configured to change or further change the beam pattern by changing the direction of a main lobe of the beam pattern.

[0038] The transmitter may be configured to change the direction of the main lobe in the same direction when the feedback information indicates a higher reception quality. In addition, the transmitter may be configured to change the direction of the main lobe in a different direction when the feedback information indicates a lower reception quality.

[0039] The transmitter may be configured to change or further change the beam pattern by continuously changing the main lobe of the beam pattern in the same direction until feedback information indicates that the characteristics of the beam pattern should be maintained.

[0040] In an embodiment, in the first operation mode, the receiver may be configured to select one of a plurality of different transmission characteristics depending on the determined reception quality and to send selection information to the transmitter indicating one of the plurality of different transmission characteristics to be used by the transmitter.

[0041] In an embodiment, in the second operation mode, the receiver may be configured to send feedback information to the transmitter.

[0042] The receiver may be configured to switch to a first operating mode for establishing a communication link between the transmitter and the receiver.Furthermore, the receiver may be configured to switch to a second mode for a time period comprising at least two changes in the transmission characteristic.

[0043] The receiver may be configured to switch to the first operation mode or the second operation mode depending on signaling information received from the sender.Alternatively, the receiver may be configured to switch to the first operation mode or the second operation mode and signal the current operation mode to the sender.

[0044] The receiver may be configured to not use the downlink channel from the transmitter to the receiver in the second mode of operation to receive control information indicating to the receiver the transmission characteristics to use.

[0045] Other embodiments provide a multi-antenna transmitter configured to establish a communication link with a receiver, wherein the multi-antenna transmitter is configured to change a beamforming pattern used for communicating with the receiver, wherein the multi-antenna transmitter is configured to further change the beamforming pattern used for communicating with the receiver depending on feedback information received from the receiver, the feedback information indicating whether a received SINR has changed or the direction of a received SINR change or whether characteristics of the beam pattern should be maintained.

[0046] In an embodiment, the feedback information comprises exactly 1 bit.

[0047] In an embodiment, in a first operating mode, the multi-antenna transmitter may be configured to select one of a plurality of different beamforming patterns for communicating with a receiver depending on selection information received from the receiver, the selection information indicating one of the plurality of different beamforming patterns to be used by the multi-antenna transmitter.

[0048] In an embodiment, in the second operating mode, the multi-antenna transmitter may be configured to change the beamforming pattern used for communicating with the receiver, wherein the multi-antenna transmitter may be configured to further change the beamforming pattern used for communicating with the receiver depending on feedback information received from the receiver.

[0049] The multi-antenna transmitter may be configured to switch to a first operating mode for establishing a communication link between the multi-antenna transmitter and a receiver, and wherein the multi-antenna transmitter may be configured to switch to a second operating mode for a time period including at least two changes of the beam pattern.

[0050] The multi-antenna transmitter may be configured to signal a change of mode to the receiver.

[0051] The multi-antenna transmitter may be an LTE transmitter.Thereby, the multi-antenna transmitter may be configured to not use the PDSCH to transmit control information in the second operation mode, the control information indicating to the receiver the beam pattern to use.

[0052] In an embodiment, the multi-antenna transmitter may be configured to iteratively further change the beamforming pattern used for communicating with the receiver depending on feedback information received from the receiver.

[0053] In an embodiment, the multi-antenna transmitter may be configured to change or further change the beam pattern by changing the direction of a main lobe of the beam pattern.

[0054] The multi-antenna transmitter may be configured to change the direction of the main lobe in the same direction when the feedback information indicates a higher SINR. In addition, the multi-antenna transmitter may be configured to change the direction of the main lobe in a different direction when the feedback information indicates a lower SINR.

[0055] In an embodiment, the multi-antenna transmitter may be configured to change or further change the beam pattern by changing the direction of the main lobe of the beam pattern in the azimuth direction and the elevation direction respectively after each other.

[0056] In an embodiment, the multi-antenna transmitter may be configured to change or further change the beam pattern by continuously changing the main lobe of the beam pattern in the same direction until feedback information indicates that the characteristics of the beam pattern should be maintained.

[0057] Other embodiments provide a receiver configured to establish a communication link with a multi-antenna transmitter, wherein the receiver is configured to determine a SINR of the communication link, wherein the receiver is configured to send feedback information to the multi-antenna transmitter indicating whether the received SINR has changed or the direction of the received SINR change or whether the beam pattern should be maintained.

[0058] In an embodiment, the feedback information comprises exactly 1 bit.

[0059] In an embodiment, in the first operation mode, the receiver may be configured to select one of a plurality of different beamforming patterns depending on the determined SINR, and send selection information indicating one of the plurality of different beamforming patterns to be used by the multi-antenna transmitter to the multi-antenna transmitter.

[0060] In an embodiment, in the second operation mode, the receiver may be configured to send feedback information to the multi-antenna transmitter.

[0061] The receiver may be configured to switch to a first operation mode for establishing a communication link between the multi-antenna transmitter and the receiver.Furthermore, the receiver may be configured to switch to a second operation mode for a time period comprising at least two changes of the beam pattern.

[0062] The receiver may be configured to switch to the first operation mode or the second operation mode depending on signaling information received from the multi-antenna transmitter.

[0063] The receiver may be an LTE receiver.Thereby, the receiver may be configured to not use the PDSCH to transmit control information in the second operation mode, the control information indicating a selected beam pattern from among a plurality of different beam patterns selected by the multi-antenna transmitter.

[0064] Other embodiments provide a method for multi-antenna transmission, the method comprising:

[0065] - Establishing a communication link with a receiver;

[0066] - changing the beamforming pattern used to communicate with the receiver; and

[0067] - further changing the beamforming pattern used for communicating with the receiver depending on feedback information received from the receiver, the feedback information indicating whether the received SINR has changed or the direction of the received SINR change or whether the characteristics of the beam pattern should be maintained.

[0068] Other embodiments provide a method for receiving, the method comprising:

[0069] - Establish a communication link with a multi-antenna transmitter;

[0070] -determine the SINR of the communication link; and

[0071] - Sending feedback information indicating whether the reception SINR has changed or the direction in which the reception SINR has changed or whether the characteristics of the beam pattern should be maintained to the multi-antenna transmitter. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Embodiments of the present invention are described herein with reference to the accompanying drawings.

[0073] Figure 1 A schematic block diagram showing a prior art communication system;

[0074] Figure 2 A schematic block diagram showing a prior art MIMO system;

[0075] Figure 3 A graph showing SINR (in dB) versus codebook size (in number of codewords) for a single user and a single base station is shown;

[0076] Figure 4 A schematic block diagram of a transmitter according to an embodiment is shown;

[0077] Figure 5 shows a schematic block diagram of a receiver according to an embodiment;

[0078] Figure 6a-6c A schematic block diagram showing a communication system including a transmitter and a receiver at different points in time;

[0079] Figure 7a-7e A schematic block diagram showing a communication system including a transmitter and a receiver at different points in time;

[0080] Figure 8 A schematic block diagram of a communication system including a multi-antenna transmitter and a receiver according to an embodiment is shown;

[0081] Fig. 9 A flow chart illustrating a method for operating a communication system including a multi-antenna transmitter and (MIMO) receiver according to an embodiment;

[0082] Fig.10 A flow chart showing a method for transmitting according to an embodiment; and

[0083] Fig.11 A flow chart of a method for receiving according to an embodiment is shown. DETAILED DESCRIPTION

[0084] In the following description, equal or equivalent elements or elements having equal or equivalent functions are denoted by equal or equivalent reference numerals.

[0085] In the following description, a number of details are set forth to provide a more comprehensive explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other cases, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention. In addition, unless otherwise specifically stated, the features of the different embodiments described hereafter may be combined with each other.

[0086] Figure 4 A schematic block diagram of a transmitter 100 for communicating with a receiver according to an embodiment of the present invention is shown. The transmitter 100 is configured to change a transmission feature for communicating with the receiver, wherein the transmitter 100 is configured to further change the transmission feature for communicating with the receiver depending on feedback information 120 received from the receiver, the feedback information 120 indicating whether the reception quality has changed or the direction of the reception quality change or whether the transmission feature should be maintained.

[0087] In an embodiment, the transmitter 100 may include at least one antenna 102, for example for transmitting a signal 122 to a receiver and / or for receiving a signal 124 from the receiver. Thus, the transmitter 100 may be a transceiver.

[0088] In an embodiment, the feedback information 120 may include exactly 1 bit.

[0089] For example, when the value of the reception quality detected by the receiver is greater than the reference value, the feedback information 120 may include a first value (e.g., logic 1), and when the value of the reception quality detected by the receiver is equal to or less than the reference value, the feedback information 120 may include a second value different from the first value (e.g., logic 0). Naturally, when the value of the reception quality detected by the receiver is less than the reference value, the feedback information may also include the first value (e.g., logic 1), and when the value of the reception quality detected by the receiver is equal to or greater than the reference value, the feedback information may also include the second value (e.g., logic 0). The reference value may be a previous value of the reception quality or a minimum value or a maximum value among a plurality of previous values ​​of the reception quality.

[0090] The reception quality may be at least one of a signal to interference plus noise ratio (SINR), a signal to noise ratio (SNR), a channel quality indicator (CQI), received signal power and effective data throughput (considering coding overhead and block error), and an interference power level.

[0091] The transmission characteristic may be one of transmit power, code rate, a set of scheduled resources, a beamforming pattern, a precoder setting, a set of access nodes for coordinated transmission in a single frequency network (eg, a set of serving or interfering transmitters).

[0092] In an embodiment, the transmitter 100 may be configured to iteratively further vary transmission characteristics used for communicating with the receiver depending on feedback information 120 received from the receiver.

[0093] In an embodiment, the transmitter 100 may be configured to switch between a first operating mode and a second operating mode.

[0094] In the first operation mode, the transmitter 100 may be configured to select one of a plurality of different transmission characteristics for communicating with the receiver depending on the selection information 130 received from the receiver. Additionally (e.g. alternatively), in the first operation mode, the transmitter 100 may be configured to randomly select one of a plurality of different transmission characteristics for communicating with the receiver. Additionally (e.g. alternatively), in the first operation mode, the transmitter 100 may be configured to select a default transmission characteristic.

[0095] In the second operation mode, the transmitter 100 may be configured to change the transmission characteristics for communicating with the receiver, wherein the transmitter 100 may be configured to further change the transmission characteristics for communicating with the receiver depending on feedback information received from the receiver.

[0096] The transmitter 100 may be configured to switch to a first operating mode for establishing a communication link between the transmitter 100 and the receiver, and to switch to a second operating mode after the communication link between the transmitter 100 and the receiver is established, e.g. for a given time period, the time period e.g. comprising at least two changes in the transmission characteristics.

[0097] Furthermore, the transmitter 100 may be configured to signal a change of the operating mode to the receiver.Alternatively, the transmitter 100 may be configured to change the operating mode depending on signaling information received from the receiver.

[0098] In addition, the transmitter 100 can be configured to not use the downlink channel from the transmitter to the receiver to send control information in the second operation mode, and the control information indicates the transmission characteristics used to the receiver. For example, signaling from the transmitter to the receiver is not used, so it is transparent to the receiver and does not increase additional signaling overhead.

[0099] Figure 5 An exemplary block diagram of a receiver 150 for communicating with a transmitter 100 according to an embodiment of the present invention is shown. The receiver 150 is configured to establish a communication link with the transmitter 100, wherein the receiver 150 is configured to determine the reception quality of the communication link, wherein the receiver 150 is configured to send feedback information 120 to the transmitter 100 indicating whether the reception quality has changed or the direction of the reception instruction change or whether the transmission feature should be maintained.

[0100] In an embodiment, the receiver 150 may include at least one antenna 152, for example, for transmitting the signal 124 to the transmitter 100 and / or receiving the signal 122 from the transmitter. The receiver 150 may be a transceiver.

[0101] In an embodiment, the feedback information 120 may include exactly 1 bit.

[0102] For example, when the value of the reception quality detected by the receiver is greater than the reference value, the feedback information 120 may include a first value (e.g., logic 1), and when the value of the reception quality detected by the receiver is equal to or less than the reference value, the feedback information 120 may include a second value different from the first value (e.g., logic 0). Naturally, when the value of the reception quality detected by the receiver is less than the reference value, the feedback information may also include the first value (e.g., logic 1), and when the value of the reception quality detected by the receiver is equal to or greater than the reference value, the feedback information may also include the second value (e.g., logic 0). The reference value may be a previous value of the reception quality or the minimum or maximum value among a plurality of previous values ​​of the reception quality.

[0103] In an embodiment, the receiver 150 may be configured to switch between a first mode of operation and a second mode of operation.

[0104] In a first operation mode, the receiver 150 may be configured to select one of a plurality of different transmission characteristics depending on the determined reception quality and to send selection information 130 to the transmitter indicating one of the plurality of different transmission characteristics to be used by the transmitter.

[0105] In the second operation mode, the receiver 150 may be configured to send the feedback information 120 to the transmitter 100 .

[0106] The receiver 150 may be configured to switch to a first operating mode for establishing a communication link or a communication channel between the transmitter 100 and the receiver 150, and to switch to a second operating mode after establishing the communication link or the communication channel between the transmitter 100 and the receiver 150, for example for a given time period, the time period for example including at least two changes in the transmission characteristics.

[0107] Furthermore, the receiver 150 may be configured to switch to the first operation mode or the second operation mode depending on signaling information received from the transmitter 100. Alternatively, the receiver 150 may be configured to switch to the first operation mode or the second operation mode and signal the current operation mode to the transmitter.

[0108] Furthermore, the receiver 150 may be configured not to use the downlink channel from the transmitter to the receiver in the second operation mode to receive control information indicating to the receiver the transmission characteristics to use.

[0109] In an embodiment, feedback information (e.g., 1-bit feedback) is sent from the receiver to the transmitter to indicate whether a specific performance indicator measured by the receiver has increased or decreased. This means that, for example, when the maximum value of the performance indicator is of interest, 1 (or 0) is sent if the value is larger, and 0 (or 1) is sent if the values ​​are the same or smaller. When the minimum value of the performance indicator is of interest, the same operation can be performed when the value is smaller. The reference value used for comparison can be the previous value (see the example in Figure 6) or the maximum / minimum value within the time when the transmitter started changing the setting. Whenever a new maximum / minimum value is received, the maximum / minimum value used for comparison is updated, see the example in Figure 7. Using this scheme, the transmitter can change the settings of the system to any desired configuration that is not limited by the feedback channel. The initial settings from which it starts are most likely obtained through the existing state of the art mechanism, but can also be random settings. Regarding the example, this can be:

[0110] First, a modulation and / or code rate is selected from it. The transmitter can change the code rate, for example a lower code rate to increase the effective data throughput. With effective data throughput, it means a throughput without redundancy added by the code and only successfully received and decoded messages. This means that on the one hand, redundancy is added and the effective throughput is reduced by increasing the code rate, and on the other hand, reducing the code rate increases the ratio of unsuccessfully received and decoded messages. In a feedback system, the receiver signals the code rate to be used from a limited set to the transmitter. With the scheme proposed here, the transmitter can change the code rate to other values ​​that are not included in the limited set (but are technically possible in the system) and obtain feedback from the receiver whether the effective data throughput has increased.

[0111] Secondly, a set of transmitters or a subset thereof. In this example, the receiver has a set of transmitters from which to select for transmission. The receiver can indicate an indication of a specific transmitter to be used or a specific set of transmitters. However, whenever the number of transmitters is large, the required feedback is also large. By measuring a specific value again (such as the receiver signal strength or signal-to-noise ratio (SNR) or signal-to-noise-plus-interference ratio SINR at the receiver), the set of transmitters can be changed and the receiver indicates whether the value is increased or decreased by 1 or 0.

[0112] Third, in wireless systems with multi-antenna transmitters, the number of beamformers / precoders. In wireless systems (e.g., WiFi, LTE) in which the transmitter has multiple antennas, the number of beamformers / precoders to be used is defined in a codebook from which the receiver can select, see Figure 6. With a large codebook, the amount of feedback for transmission indications also increases. Using the proposed 1-bit feedback scheme, the transmitter can change the beamformer / precoder to improve a specific performance indication at the receiver. This performance indication can be, but is not limited to, received signal power, SNR, SINR, block error rate, bit error rate, interference plus noise power.

[0113] Fourth, wireless systems with resource pools such as frequency domain, space domain or code domain. In wireless systems with large resource pools such as frequency domain, space domain or code domain, users must report which resource is the best resource to be used by the transmitter. This requires a lot of feedback from the receiver. This problem is even more severe in shared access systems when multiple receivers use the same uplink channel (control, feedback or data channel) to feedback their resources. Using the proposed 1-bit scheme, the transmitter can arrange specific resources for the receiver and then start changing the resources assigned to the receiver based on the user's 1-bit feedback. Again, the measured values ​​can be, but are not limited to, its received signal power, SNR, SINR, block error rate, bit error rate, interference plus noise power.

[0114] Figure 6a-6c 1 shows a schematic block diagram of a communication system 180 including a transmitter 100 and a receiver 150 at different points in time. The transmitter 100 and the receiver 150 communicate on a communication channel 182 that overlaps with noise 184. In other words, Figure 6a-6c A communication system based on 1-bit feedback is shown using an example where a previous value is used for comparison. Here, the minimum value is of interest, and smaller measured performance indicators are indicated using 0, and equal or greater values ​​are indicated using 1.

[0115] exist Figure 6a In the embodiment, at a first time point (time point 1), the transmitter 100 is configured to communicate with the receiver 150 using a first transmission feature (configuration n1), wherein the receiver 150 is configured to determine (eg, measure) a reception quality to obtain a first performance indication (PI1).

[0116] exist Figure 6b, at a second time point (time point 2), the transmitter 100 is configured to change the transmission characteristic from the first transmission characteristic (configuration n1) to a second transmission characteristic (configuration n2) different from the first transmission characteristic, wherein the receiver 150 is configured to determine the reception quality, obtain a second performance indication (PI2), compare the second performance indication (PI2) with a reference value, and provide 1-bit feedback information based on the comparison between the second performance indication (PI2) and the reference value. As exemplarily shown in FIG6 , the reference value is the previous performance indication, i.e., the first performance indication (PI1). In the example shown in FIG6 , Figure 6b In the example of , the second performance indicator (PI2) is less than the first performance indicator (PI1) so that the 1-bit feedback information includes a logic 0.

[0117] exist Figure 6c , at a third time point (time point 3), the transmitter 100 is configured to change the transmission characteristic from the second transmission characteristic (configuration n2) to a third transmission characteristic (configuration n3) different from the second transmission characteristic, wherein the receiver 150 is configured to determine the reception quality to obtain a third performance indicator (PI3), compare the third performance indicator (PI3) with a reference value, and provide 1-bit feedback information based on the comparison between the third performance indicator (PI3) and the reference value. Figure 6c As shown in the example, the reference value is the previous performance indicator, namely the second performance indicator (PI2). Figure 6c In the example shown, the third performance indicator (PI3) is greater than or equal to the second performance indicator (PI2), so that the 1-bit feedback information includes a logical 1.

[0118] Figure 7a-7e 1 shows a schematic block diagram of a communication system 180 including a transmitter 100 and a receiver 150 at different points in time. The transmitter 100 and the receiver 150 communicate on a communication channel 182 that overlaps with noise 184. In other words, Figure 7a-7e A communication system based on 1-bit feedback is illustrated using an example in which a minimum value is used for comparison.

[0119] exist Figure 7a In the embodiment, at a first time point (time point 1), the transmitter 100 is configured to communicate with the receiver 150 using a first transmission feature (configuration n1), wherein the receiver 150 is configured to determine (eg, measure) a reception quality to obtain a first performance indication (PI1).

[0120] exist Figure 7bIn the embodiment, at a second time point (time point 2), the transmitter 100 is configured to change the transmission characteristic from the first transmission characteristic (configuration n1) to a second transmission characteristic (configuration n2) different from the first transmission characteristic, wherein the receiver 150 is configured to determine the reception quality to obtain a second performance indication (PI2), compare the second performance indication (PI2) with the reference indication, and provide 1-bit feedback information based on the comparison between the second performance indication (PI2) and the reference indication. Figure 7b As shown in FIG, the reference indication is the minimum indication among the previous performance indications. Since the first performance indication (PI1) is the minimum indication among the previous performance indications or is the only available performance indication, the receiver 150 is configured to compare the second performance indication (PI2) with the first performance indication (PI1). Figure 7b In the example of , the second performance indicator (PI2) is smaller than the first performance indicator (PI1), so that the 1-bit feedback information includes a logic 0. The second performance indicator is a new reference indicator.

[0121] exist Figure 7c In the embodiment, at a third time point (time point 3), the transmitter 100 is configured to change the transmission characteristic from the second transmission characteristic (configuration n2) to a third transmission characteristic (configuration n3) different from the second transmission characteristic, wherein the receiver 150 is configured to determine the reception quality to obtain a third performance indicator (PI3), compare the third performance indicator (PI3) with a reference value, and provide 1-bit feedback information based on the comparison between the third performance indicator (PI3) and the reference value. Figure 7c As exemplarily shown in FIG. , the reference indication is the minimum indication among the previous performance indications. Since the second performance indication (PI2) is the minimum indication among the previous performance indications, the receiver 150 is configured to compare the second performance indication (PI2) with the third performance indication (PI3). Figure 7c In the example of , the third performance indicator (PI3) is greater than or equal to the second performance indicator (PI2), so that the 1-bit feedback information includes a logic 1. The second performance indicator is still a reference indicator.

[0122] exist Figure 7d , at a fourth time point (time point 4), the transmitter 100 is configured to change the transmission characteristic from the third transmission characteristic (configuration n3) to a fourth transmission characteristic (configuration n4) different from the third transmission characteristic, wherein the receiver 150 is configured to determine the reception quality to obtain a fourth performance indicator (PI4), compare the fourth performance indicator (PI4) with a reference value, and provide 1-bit feedback information based on the comparison between the fourth performance indicator (PI4) and the reference value. Figure 7dAs exemplarily shown in FIG. , the reference indication is the minimum indication among the previous performance indications. Since the second performance indication (PI2) is the minimum indication among the previous performance indications, the receiver 150 is configured to compare the second performance indication (PI2) with the fourth performance indication (PI4). Figure 7d In the example of , the fourth performance indicator (PI4) is smaller than the second performance indicator (PI2), so that the 1-bit feedback information includes a logic 0. The fourth performance indicator is a new reference indicator.

[0123] exist Figure 7e , at a fifth time point (time point 5), the transmitter 100 is configured to change the transmission characteristic from the fourth transmission characteristic (configuration n4) to a fifth transmission characteristic (configuration n5) different from the fourth transmission characteristic, wherein the receiver 150 is configured to determine the reception quality to obtain a fifth performance indication (PI5), compare the fifth performance indication (PI5) with a reference value, and provide 1-bit feedback information based on the comparison between the fifth performance indication (PI5) and the reference value. Figure 7e As exemplarily shown in FIG. , the reference indication is the minimum indication among the previous performance indications. Since the fourth performance indication (PI4) is the minimum indication among the previous performance indications, the receiver 150 is configured to compare the fifth performance indication (PI5) with the fourth performance indication (PI4). Figure 7e In the example of , the fifth performance indicator (PI5) is greater than or equal to the fourth performance indicator (PI4), so that the 1-bit feedback information includes a logic 1. The fourth performance indicator is still a reference indicator.

[0124] Figure 8 A schematic block diagram of a communication system 180 including a multi-antenna transmitter 100 and a receiver 150 according to an embodiment is shown.

[0125] The transmitter 100 may be configured to establish a communication link with the receiver 150, wherein the multi-antenna transmitter 100 is configured to change a beamforming pattern for communicating with the receiver 150, wherein the multi-antenna transmitter 100 may be configured to further change the beamforming pattern for communicating with the receiver 150 depending on feedback information 120 received from the receiver 150, the feedback information 120 indicating whether the received SINR has changed or the direction of the received SINR change or whether a characteristic of the beam pattern should be maintained.

[0126] The receiver 150 may be configured to establish a communication link with the multi-antenna transmitter 100, wherein the receiver 150 may be configured to determine the SINR of the communication link, wherein the receiver 150 may be configured to send feedback information 120 to the multi-antenna transmitter 100 indicating whether the received SINR has changed or the direction of the received SINR change or whether the characteristics of the beam pattern should be maintained.

[0127] For example, multi-antenna transmitter 100 may include multiple antennas 102 for transmitting signal 122 to receiver 150 and receiving signal 124 from receiver 150. Receiver 150 may include one antenna or more than one antenna 152 for receiving signal 122 from transmitter 100 and transmitting signal 124 to transmitter 100 (i.e., receiver 150 may be a multi-antenna receiver).

[0128] The feedback information 120 may include exactly 1 bit, ie, a logic 1 or a logic 0.

[0129] For example, when the value of the received SINR is greater than the reference value, the feedback information 120 may include a first value (e.g., logic 1), and when the value of the received SINR is equal to or less than the reference value, the feedback information 120 may include a second value different from the first value (e.g., logic 0). Naturally, when the value of the received SINR is less than the reference value, the feedback information may also include a first value (e.g., logic 1), and when the value of the received SINR is equal to or greater than the reference value, the feedback information may also include a second value (e.g., logic 0). The reference value may be a previous value of the SINR or a minimum or maximum value among multiple previous values ​​of the SINR.

[0130] In an embodiment, the multi-antenna transmitter 100 may be configured to, in a first operating mode, select one of a plurality of different beamforming patterns (e.g., from a codebook) depending on selection information received from the receiver 150, the selection information (e.g., a codebook index) indicating one of the plurality of different beamforming patterns to be used by the multi-antenna transmitter.

[0131] Furthermore, the multi-antenna transmitter 100 may be configured to change the beamforming pattern used for communicating with the receiver 150 in the second operation mode, wherein the multi-antenna transmitter 100 may be configured to further change the beamforming pattern used for communicating with the receiver depending on feedback information received from the receiver.

[0132] In an embodiment, the receiver 150 may be configured to select one of a plurality of different beamforming patterns (e.g., from a codebook) in a first operating mode depending on a determined SINR, and send selection information (e.g., a codebook index) indicating one of the plurality of different beamforming patterns used by the multi-antenna transmitter 100 to the multi-antenna transmitter 100.

[0133] Furthermore, the receiver 150 may be configured to send feedback information 120 to the multi-antenna transmitter 100 in the second operation mode.

[0134] In an embodiment, the multi-antenna transmitter 100 may be configured to switch to a first operating mode for establishing a communication link between the multi-antenna transmitter 100 and the receiver 150, and wherein the multi-antenna transmitter 100 may be configured to switch to a second operating mode for a time period including at least two changes of the beam pattern.

[0135] Similarly, the receiver 150 may be configured to switch to a first operating mode for establishing a communication link between the multi-antenna transmitter 100 and the receiver 150, and wherein the receiver 150 is configured to switch to a second operating mode for a time period including at least two changes of the beam pattern.

[0136] The multi-antenna transmitter 100 may be configured to send signaling information to the receiver 150, the signaling information signaling the receiver of the change in operating mode.

[0137] The receiver 150 may be configured to switch to the first operation mode or the second operation mode depending on the signaling information received from the multi-antenna transmitter 100 .

[0138] In an embodiment, a large codebook can be used without additional signaling in the PDSCH by using 1-bit feedback from the receiver 150 to the transmitter 100, which indicates whether the received SINR is increased after changing the beamformer / precoder selected for the receiver at the transmitter side without informing the receiver of the change.

[0139] Embodiments enable almost unlimited codebooks or quantization of channels. The codebook structure of the full-dimensional codebook C_FD is theoretically the following assuming a rectangular-shaped antenna array at the transmitter:

[0140] C_FD=C_v⊗C_h

[0141] where C_v is the codebook for elevation beamforming and C_h is the codebook for azimuth beamforming. Details can be found in [3GPP, “Study on Elevation Beamforming / Full-Dimension (FD) MIMO forLTE”, 3rd Generation Partnership Project, Vol. 13.0.0, July 2015] and [YH Nam, MS Rahman, Y. Li, G. Xu, E. Onggosanusi, J. Zhang and JY Seol, “Fulldimension MIMO for LTE-Advanced and 5G”, Information Theory and Applications Workshop (ITA), 2015, pp. 143-148, February 2015]. To construct C_v and C_h, the Discrete Fourier Transform (DFT) matrix can be used. This means a structured codebook where a specific column (stream) of the codebook corresponds to a specific direction. This side information can be exploited in the following steps:

[0142] 1. Each receiver selects the most suitable beamformer (column) from C_FD;

[0143] 2. Each receiver feeds back the precoding matrix indication (PMI) corresponding to the selected entry from step 1;

[0144] 3. The transmitter starts transmitting to the receiver using the beamformer selected in step 2;

[0145] 4. The transmitter tells the receiver that it is now starting the fast 1-bit feedback mode.

[0146] 5. The transmitter begins modifying the beamformer so that the main lobe of the beam is different from the beamformer used in step 3 or the previous iteration of step 5;

[0147] 6. If the received SINR of the beamformer used in step 5 is higher (feedback 1) or lower (feedback 0) than the received SINR of the beamformer used in step 3 or the previous iteration of step 5, the receiver sends a 1-bit feedback;

[0148] Based on the feedback in step 6, the process of further beamformer changes is continued with step 5 or terminated, depending on the specific algorithm of each operator.

[0149] Fig. 9 1 is a flow chart showing a method 200 for operating a communication system comprising a multi-antenna transmitter 100 and a (multi-antenna) receiver 150 according to an embodiment. In other words, Fig. 9 One implementation of the process in which the beamformers are changed in azimuth and elevation directions respectively after each other is shown.

[0150] In the first operation mode (first stage) 202, the receiver 150 may be configured to select one of a plurality of different beamforming patterns (e.g., from a codebook) depending on the determined SINR, and transmit selection information (e.g., a codebook index) indicating one of the plurality of different beamforming patterns used by the multi-antenna transmitter 100 to the multi-antenna transmitter 100. The multi-antenna transmitter 100 may be configured to select one of the plurality of different beamforming patterns (e.g., from a codebook) for communicating with the receiver depending on the selection information (e.g., the codebook index) received from the receiver 150.

[0151] For example, Fig. 9 As shown, in a first operation mode 202, a transmitter 100 (e.g., a base station) may send channel state information (CSI) and a demodulation reference signal DRMS ​​to a receiver 150 (e.g., a user equipment (UE)). The receiver 150 may be configured to measure 204 the SINR and save it for comparison purposes. In addition, the receiver 150 may be configured to send the PMI to the transmitter 100.

[0152] In the second operation mode (Phase 2) 206, the multi-antenna transmitter may be configured to change the beamforming pattern used for communicating with the receiver 150. The receiver may be configured to determine the SINR of the communication link and send feedback information indicating that the received SINR is high (e.g., logic 1) or low (e.g., logic 0) to the multi-antenna transmitter 100. The multi-antenna transmitter 100 may be configured to further change the beamforming pattern used for communicating with the receiver 150 depending on the feedback information received from the receiver 150. Subsequently, the multi-antenna transmitter 100 may be configured to iteratively further change the beamforming pattern used for communicating with the receiver 150 depending on the feedback information received from the receiver.

[0153] The multi-antenna transmitter 100 may be configured to change or further change the beam pattern by changing the direction of the main lobe of the beam pattern. Thus, the multi-antenna transmitter may be configured to change or further change the beam pattern by changing the direction of the main lobe of the beam pattern in the azimuth direction and the elevation direction separately or jointly after each other.

[0154] like Fig. 9 As indicated, the multi-antenna transmitter 100 may be configured to change or further change the beam pattern by continuously changing the main lobe of the beam pattern in the same direction until the feedback information indicates that the characteristics of the beam pattern should be maintained. For example, in the feedback information, another bit (e.g., two bits of feedback in total) may be added to indicate that the transmission strategy is maintained or the transmission strategy should be updated using predictions or other side information. Alternatively, information may be included as to how long the transmission strategy should be maintained or fixed.

[0155] Specifically, in the second operation mode (second stage) 206, the transmitter 100 may be configured to move the main lobe in the elevation direction. The receiver may be configured to measure 206 the SINR and send 1-bit feedback information to the multi-antenna transmitter 100 depending on the measured SINR. For example, if the current SINR (or new SINR) is less than 208 the previous SINR (or old SINR), the feedback information may include a logic 0, wherein if the current SINR (or new SINR) is greater than 210 the previous SINR (or old SINR), the feedback information may include a logic 1. Thus, the multi-antenna transmitter may be configured to continuously move 212 the beam until it receives a logic 1, i.e., until the current SINR (or new SINR) is greater than the previous SINR (or old SINR). This process may be repeated until 1 bit is received when the multi-antenna transmitter starts to move 214 the beam in the azimuth direction. Similarly, the receiver may be configured to measure 206 the SINR and send 1-bit feedback information to the multi-antenna transmitter 100 depending on the measured SINR. When the multi-antenna transmitter 100 receives 1 bit, it stops moving 216 the beamformer.

[0156] Fig.10 A flow chart of a method 300 for transmitting is shown. The method 300 comprises a step 302 of establishing a communication link with a receiver. Furthermore, the method 300 comprises a step 304 of changing a transmission characteristic for communicating with the receiver. Furthermore, the method 300 comprises a step 306 of further changing a transmission characteristic for communicating with the receiver depending on feedback information received from the receiver, the feedback information indicating whether the reception quality has changed or the direction of the reception quality change or whether the transmission characteristic should be maintained.

[0157] Fig.11 A flow chart of a method 320 for receiving is shown. The method 320 comprises a step 322 of establishing a communication link with a transmitter. Furthermore, the method 300 comprises a step 324 of determining a reception quality of the communication link. Furthermore, the method 320 comprises a step 326 of sending feedback information to the transmitter indicating whether the reception quality has changed or the direction in which the reception quality has changed or whether the transmission feature should be maintained.

[0158] In an embodiment, additional fast 1-bit feedback based on the rate of change of the beamformer at the transmitter is provided and included in the protocol, indicating whether the changed beamformer has a higher received SNR / SINR than the previous beamformer compared to the last or maximum value within a certain window in the past.

[0159] Embodiments provide at least one of the following advantages. First, the receive SNR is increased by utilizing a codebook with virtually unlimited size, since an arbitrary step size for changing the beamformer direction can be chosen and is only limited by the hardware at the transmitter. Second, no additional signaling overhead in the PDSCH is required. Third, due to the low additional 1-bit feedback, very short feedback intervals per TTI (TTI = Transmission Time Interval) are enabled.

[0160] Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent descriptions of corresponding methods, wherein a block or device corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method step also represent descriptions of corresponding blocks or items or features of a corresponding apparatus. Some or all of the method steps may be performed by (or using) hardware devices, such as a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such a device.

[0161] Depending on the specific implementation requirements, embodiments of the present invention may be implemented in hardware or software. The implementation may be performed using a digital storage medium, such as a floppy disk, DVD, Blu-ray, CD, ROM, PROM, EPROM, EEPROM or flash memory, on which electronically readable control signals are stored, which cooperate (or are capable of cooperating) with a programmable computer system in order to perform the corresponding method. Thus, the digital storage medium may be computer readable.

[0162] Some embodiments according to the invention comprise a data carrier having electronically readable control signals, which are capable of cooperating with a programmable computer system, such that one of the methods described herein is performed.

[0163] Generally, embodiments of the present invention can be implemented as a computer program product with a program code, the program code being operative for performing one of the methods when the computer program product runs on a computer.For example, the program code may be stored on a machine readable carrier.

[0164] Other embodiments comprise the computer program for performing one of the methods described herein, stored on a machine readable carrier.

[0165] In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing one of the methods described herein, when the computer program runs on a computer.

[0166] A further embodiment of the inventive methods is, therefore, a data carrier (or a digital storage medium, or a computer-readable medium) comprising, recorded thereon, the computer program for performing one of the methods described herein. The data carrier, the digital storage medium or the recorded medium are typically tangible and / or non-transitory.

[0167] A further embodiment of the inventive method is, therefore, a data stream or a sequence of signals representing the computer program for performing one of the methods described herein.For example, the data stream or the sequence of signals may be configured to be transmitted via a data communication connection, for example via the Internet.

[0168] A further embodiment comprises processing means, for example a computer or a programmable logic device, configured to or adapted to perform one of the methods described herein.

[0169] A further embodiment comprises a computer having installed thereon the computer program for performing one of the methods described herein.

[0170] Another embodiment according to the invention comprises an apparatus or system configured to transmit (e.g. electronically or optically) a computer program for performing one of the methods described herein to a receiver. For example, the receiver may be a computer, a mobile device, a memory device, etc. For example, the apparatus or system may comprise a file server for transmitting the computer program to the receiver.

[0171] In some embodiments, a programmable logic device (e.g., a field programmable gate array) can be used to perform some or all of the functions of the methods described herein. In some embodiments, the field programmable gate array can cooperate with a microprocessor to perform one of the methods described herein. Generally, the method is preferably performed by any hardware device.

[0172] The devices described herein may be implemented using hardware devices, or using computers, or using a combination of hardware devices and computers.

[0173] The apparatus described herein, or any component of an apparatus described herein, may be implemented at least partially in hardware and / or software.

[0174] The methods described herein may be performed using a hardware device, or using a computer, or using a combination of a hardware device and a computer.

[0175] Any component of a method described herein, or an apparatus described herein, may be performed at least in part by hardware and / or software.

[0176] The embodiments described above are merely illustrative of the principles of the present invention. It should be understood that modifications and variations of the arrangements and details described herein will be apparent to other persons skilled in the art. Therefore, it is intended that the scope of the present invention be limited only by the scope of the appended patent claims, and not by the specific details presented in the description and explanation of the embodiments herein.

Claims

1. A transmitter (100) for communicating with a receiver (150), wherein the transmitter (100) is configured in a first operating mode to change a transmit power for communicating with the receiver (150), wherein the transmitter (100) is configured to further change the transmit power for communicating with the receiver (150) depending on feedback information (120) received from the receiver (150), the feedback information (120) indicating whether a received signal power should be increased or decreased or whether the transmit power should be maintained, in, The transmitter is configured in a second operation mode to select one of a plurality of different transmit powers for communicating with the receiver depending on selection information received from the receiver, or wherein the transmitter is configured in the second operation mode to select a default transmit power.

2. The transmitter (100) according to claim 1, wherein: The feedback information (120) comprises exactly 1 bit.

3. The transmitter (100) according to claim 2, wherein: When the value of the received signal power detected by the receiver (150) is greater than a reference value, the feedback information (120) includes a first value, and when the value of the received signal power detected by the receiver (150) is equal to or less than the reference value, the feedback information (120) includes a second value different from the first value; or wherein, when the value of the received signal power detected by the receiver (150) is less than the reference value, the feedback information (120) includes a first value, and when the value of the received signal power detected by the receiver (150) is equal to or greater than the reference value, the feedback information (120) includes a second value different from the first value; The reference value is a previous value of the received signal power, or a minimum value or a maximum value among a plurality of previous values ​​of the received signal power.

4. The transmitter (100) according to claim 1, wherein: The transmitter (100) is configured to switch to the first operating mode for establishing a communication link between the transmitter (100) and the receiver (150), and wherein the transmitter (100) is configured to switch to the second operating mode for a time period including at least two changes of the transmission power.

5. The transmitter (100) according to claim 1, wherein: The transmitter (100) is configured to signal a change of an operating mode to the receiver (150), or wherein the transmitter (100) is configured to change the operating mode depending on signaling information received from the receiver (150).

6. The transmitter (100) according to claim 1, wherein: The transmitter (100) is configured not to use a downlink channel from the transmitter (100) to the receiver (150) to transmit control information in the second operation mode, the control information indicating to the receiver (150) a transmit power to use.

7. The transmitter (100) according to claim 1, wherein: The transmitter (100) is configured to iteratively further vary the transmit power used for communicating with the receiver (150) depending on the feedback information received from the receiver (150).

8. A receiver (150), wherein: The receiver is used to establish a communication link with a transmitter (100), wherein the receiver (150) is configured to determine a received signal power of the communication link, wherein the receiver (150) is configured in a first operation mode to send feedback information to the transmitter (100) indicating whether the received signal power is increased or decreased or whether the transmission power should be maintained, The receiver is configured in the second operation mode to select one of a plurality of different transmit powers depending on the determined received signal power, and to send selection information indicating one of the plurality of different transmit powers to be used by the transmitter to the transmitter.

9. The receiver (150) of claim 8, wherein the feedback information comprises exactly 1 bit.

10. The receiver (150) according to claim 9, wherein when the value of the received signal power detected by the receiver (150) is greater than a reference value, the feedback information includes a first value, and when the value of the received signal power detected by the receiver (150) is equal to or less than the reference value, the feedback information includes a second value different from the first value; or wherein when the value of the received signal power detected by the receiver (150) is less than a reference value, the feedback information includes a first value, and when the value of the received signal power detected by the receiver (150) is equal to or greater than the reference value, the feedback information includes a second value different from the first value; The reference value is a previous value of the received signal power, or a minimum value or a maximum value among a plurality of previous values ​​of the received signal power.

11. The receiver (150) of claim 8, wherein: The received signal power is at least one of a signal to interference plus noise ratio, a signal to noise ratio, a channel quality indicator, a received signal power, and an effective data throughput.

12. The receiver (150) of claim 8, wherein: The receiver (150) is configured to switch to the first operating mode for establishing a communication link between the transmitter (100) and the receiver (150), and wherein the receiver (150) is configured to switch to the second operating mode for a time period that includes at least two changes in transmit power.

13. The receiver (150) of claim 8, wherein: The receiver (150) is configured to switch to the first operating mode or the second operating mode depending on signaling information received from the transmitter (100), or wherein the receiver (150) is configured to switch to the first operating mode or the second operating mode and signal the current operating mode to the transmitter (100).

14. The receiver (150) of claim 8, wherein: The receiver (150) is configured to not use a downlink channel from the transmitter (100) to the receiver (150) in the second operation mode to receive control information indicating to the receiver (150) a transmit power to use.

15. A system comprising: The transmitter (100) according to claim 1; as well as A receiver (150) as claimed in claim 8.

16. A method for sending, the method comprising: establishing a communication link with a receiver (150); In the first operating mode, varying a transmit power used to communicate with the receiver (150); further varying the transmit power used for communicating with the receiver (150) depending on feedback information (120) received from the receiver (150), the feedback information (120) indicating whether reception quality has changed or the direction in which reception quality has changed or whether the transmit power should be maintained; In the second operating mode, One of a plurality of different transmit powers for communicating with the receiver is selected depending on selection information received from the receiver, or a default transmit power is selected.

17. A method for receiving, the method comprising: establishing a communication link with a transmitter (100); determining a reception quality of the communication link; as well as In the first operating mode, sending feedback information (120) indicating whether the reception quality has changed or the direction in which the reception quality has changed or whether the transmission power should be maintained to the transmitter (100); In the second operating mode, selecting one of a plurality of different transmission powers depending on the determined reception quality, and Selection information indicating one of a plurality of different transmission powers to be used by the transmitter is transmitted to the transmitter.

18. A computer program product for executing the method of claim 16 or 17.

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