FIELD

[0001] The disclosure relates to a method for power saving in a radio receiver of a device and a device implementing such method. The invention further provides one or more computer readable media that store instructions to implement a method for power saving in a radio receiver of a device. In particular, the disclosure relates to techniques for substantial power saving in connected mode, in particular 3 GPP LTE connected mode with low to medium throughput.

BACKGROUND

[0002] In a conventional radio communication system 100, e.g. as illustrated in Fig. 1 downlink transmission 101 from radio cell 110 to mobile station 120 may include information regarding power control of the mobile station. A power up command 102 may signal the mobile station 120 to operate in normal power mode while a power down command 104 may signal the mobile station 120 to operate in power saving mode. However, latencies for decoding the power up and power down commands 102, 104, signaling and shutting down the receive path decrease the power saving performance. There is a need to improve power saving performance in the mobile device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The accompanying drawings are included to provide a further understanding of embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description.

[0004] Fig. 1 is a schematic diagram illustrating a conventional radio communication system [0005] Fig. 2 schematically illustrates an exemplary method 200 for power saving in a radio receiver according to a first aspect of the disclosure.

[0006] Fig. 3 schematically illustrates an exemplary method 300 for power saving in a radio receiver according to a first aspect of the disclosure.

[0007] Figs. 4 and 5 schematically illustrate exemplary time-frequency grids of modulation symbols forming a subframe of a radio channel.

[0008] Fig. 6 illustrates an exemplary LTE subframe timing and highlights the first and second section of the subframe for the different micro-sleep modes, when controlling the power supply to the reception power domain of a radio receiver.

[0009] Fig. 7 shows a basic state diagram for switching the operation mode of the radio receiver between a normal mode and micro-sleep mode.

[0010] Fig. 8 schematically illustrates an exemplary method for power saving in a radio receiver according to a second aspect of the disclosure.

[0011] Fig. 9 illustrates an exemplary construction of a micro-sleep pattern for determining the micro-sleep mode to be used in respective subframes of a sequence of subframes.

[0012] Fig. 10 shows a mobile device according to an embodiment of this disclosure.

[0013] Fig. 11 shows an exemplary time-frequency grid of resource elements (REs) forming a subframe of a radio channel.

[0014] Fig. 12 shows an exemplary time-frequency grid of resource elements forming a subframe of a radio channel of an OFDM-based mobile communication system, such as for example 3 GPP LTE-based systems.

[0015] Fig. 13 shows the operation of a radio receiver in a continuous reception mode in case of receiving data within a subframe and a normal micro-sleep mode in case of receiving no data within a subframe.

[0016] Fig. 14 shows the operation of a radio receiver in a normal micro-sleep mode, a maximum micro-sleep mode and a reduced micro-sleep mode according to this disclosure. DETAILED DESCRIPTION

[0017] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the invention may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0018] The methods and devices described herein may be based on power saving and power saving circuits in mobile devices and radio receivers. The mobile devices and radio receivers may be usable within an Orthogonal Frequency Division Multiplexing (OFDM)-based mobile communication network, such as for example a system based on 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), i.e. LTE Release 8 or higher.

[0019] The methods and devices described below may be implemented in mobile devices (or mobile stations or user equipments (UE)). The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives.

[0020] It is understood that comments made in connection with a described method may also hold true for a corresponding device configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include circuitry or a unit to perform the described method step, even if such circuitry or unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

[0021] The methods and devices described herein may be configured to transmit and/or receive radio signals. Reception of a radio signal may for example include demodulation of the signal received via one or more antennas and decoding the demodulated signal to obtain information. Transmission of a radio signal may for example include encoding information and modulating the encoded information to obtain a signal transmitted via one or more antennas. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender) with a radio frequency lying in a range of about 3 Hz to 300 GHz. The frequency range may correspond to frequencies of alternating current electrical signals used to produce and detect radio waves.

[0022] In the following, embodiments are described with reference to the drawings, wherein like reference numerals are generally utilized to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects of embodiments. However, it may be evident to a person skilled in the art that one or more aspects of the embodiments may be practiced with a lesser degree of these specific details. The following description is therefore not to be taken in a limiting sense.

[0023] The various aspects summarized may be embodied in various forms. The following description shows by way of illustration various exemplary embodiments and implementations in which the aspects may be practiced. It is understood that the described aspects and/or embodiments are merely examples, and that other aspects and/or embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present disclosure.

[0024] The terminology used in this disclosure is first summarized, for consistency and ease of description thereafter. While this invention may be applied in a wide range of communication systems, LTE terminology is used where applicable for convenience of description.

[0025] For an easier reference, an example time-frequency grid of communication signals is shown in Fig. 11. This example grid occupies a subframe in the time domain, which is an LTE term for transmission time interval (TTI). A subframe, or a TTI, is a temporal format designed to hold a block of signals, such that decoding the block does not require a block in another subframe. A subframe comprises one or more resource element (RE), more generally known as modulation symbol, which occupies a frequency unit of subcarrier and a time unit of an OFDM symbol. In Fig. 11, an RE is represented by a single rectangle. Thus a subframe comprises one or more OFDM symbols, and a system bandwidth comprises one or more subcarriers, where the system bandwidth is the total frequency bandwidth used by a transmitter-receiver link. While the basic time unit is called OFDM symbol, this grid structure can be used to illustrate any waveform whose modulation symbols can logically be represented by distinct time-frequency positions. [0026] An example resource element mapping to the time-frequency grid in an LTE system is shown in Fig. 12. Rectangles having a checkerboard filling denote REs carrying control channel signals, and the striped REs denote reference signals (RS). In LTE, the control channel may include physical control format indicator channel (PCFICH), physical hybrid automatic repeat request indicator channel (PHICH), and physical downlink control channel (PDCCH). The set of OFDM symbols containing control channel REs may also be referred as the control channel region. A communication system may support multiple types of reference signals. For instance, one type may be intended for channel estimation of control signals, another type may be designed for channel estimation of data signals, and still another type may be assigned for channel quality measurement. Two types of LTE reference signals are shown in Fig. 12. REs filled with stripes inclined 45° to the right denote cell-specific reference signals (CRS) and REs filled with stripes inclined 45° to the left denote channel state information-reference signals (CSI-RS). A receiver may use CRS for control signal decoding and CSI-RS for channel quality measurement. For a given receiver operation, all or only a part of a reference signal type may be used. That is, a receiver may choose to use a subset of reference signals to reduce computation and/or to reduce power consumption. As an example, a UE may choose to use the CRS (reference signal type 1 in the Fig. 12) in only the OFDM symbol 0 for estimating the channel that the control channel signals underwent, disregarding the CRS in the OFDM symbols 4, 7, and 11.

[0027] An exemplary power saving operation of a radio receiver is shown in Fig. 13. The top row of rectangles represent OFDM symbols of contiguous stream of subframes received. The OFDM symbols 0, 1, 2 may comprise the control channel region as explained in connection with Figs. 11 and 12 previously. The middle and the bottom rows represent an exemplary receiver operation in two different scenarios: The middle row corresponds to the reception and processing of a subframe containing data signals, and the bottom row corresponds to the reception and processing of a subframe without data signals. The presence and absence of data signals is indicated by the control channel of the subframe. As illustrated in Fig. 13, circuit components (or circuit blocks) forming the radio receiver may be partitioned into multiple power domains, where a power domain referred to in this disclosure is a logical entity that may comprise one or more groups of physical circuit blocks, such that the power supply of each group and, hence, each power domain, can be independently controlled. For instance, the radio frequency (RF), analog baseband, and parts of digital baseband blocks that are used for capturing an intended radio signal in the time-frequency format of the communication system may be classified as a "reception power domain", and the parts of digital baseband blocks that are used to map the captured signal format into useful information may be classified as a "decoding power domain".

[0028] The reception power domain may for example comprise circuit blocks that facilitate one or more of the following functions: low-noise amplification, frequency down-conversion, analog-to-digital conversion, gain (signal level) control, RF impairment estimation and compensation, frequency synchronization, time synchronization, antenna beam synchronization, and FFT (fast Fourier transform). In another example, the reception power domain may be further partitioned into an analog reception power domain and a digital reception power domain, to better reflect different electrical characteristics of analog and digital circuit components.

[0029] The decoding power domain may for example comprise circuit blocks that facilitate one or more of the following functions: channel estimation, demapping and demodulation, channel decoding (error correction), HARQ (hybrid automatic repeat request) combining, and channel state information estimation.

[0030] A typical radio receiver, as shown in Fig. 13, may have multiple modes of operation depending on the signal composition of a subframe, where a mode of operation is a distinct combination of power domain states. In the example of Fig. 13, when the radio receiver, upon receiving and decoding the control channel of a subframe, discovers that the subframe contains data signals, the reception power domain is kept powered on to continue the reception of data. When the radio receiver, upon receiving and decoding the control channel, discovers that the subframe does not contain data signals, the reception power domain may be powered off until the start of the next subframe to reduce power consumption. This power saving behavior of switching the power of power domains on and off within a subframe is called "micro-sleep", and the particular micro-sleeping after decoding the control channel of a subframe is referred to as "normal micro-sleep", which is the prevalent form of micro-sleep. As also shown in Fig. 13, turning the power of a power domain on or off requires a transient phase (time) for signaling the switch between the power states and for settling the associated electrical characteristics to steady states. Such transient phases are referred to as Rx turn-off and Rx turn-on in Fig. 13 and in this disclosure and can occupy a significant fraction of the subframe length, especially for radio frequency (RF) and analog blocks. Thus the reception power domain may be further partitioned into analog and digital domains, or into even smaller domains to facilitate finer control of power consumption of the radio receiver. [0031] In the following, the disclosure mainly focuses on the whole reception power domain for an easier understanding, but of course the power domain may be further sub-divided in sub-domains as appropriate. In this disclosure, a "power off period is referred to as a contiguous time interval comprising an Rx turn-off transient phase, a power down phase where the associated power domain is in a stable low-power state (sometimes also referred to as a power down state), and an Rx turn-on transient phase. In some exemplary implementations of normal micro-sleep, the time required for decoding the control channel may require as substantial duration of time in comparison to the duration of a subframe, so that the actual power down phase of the reception power domain may be only a small fraction of the subframe when there is no data in the subframe.

[0032] A first aspect of this disclosure generally relates to extending the power-saving time period of a radio receiver within a subframe in a variable manner to both maximize the micro- sleep duration and to allow receiving reference signals that the radio receiver may require for performing one or more reference signal-based tasks. Fig. 14 shows examples of three micro- sleep operation modes: normal micro-sleep, maximum micro-sleep, and reduced micro-sleep. The latter two may be classified as submodes of a "no-data" micro-sleep mode. The normal micro-sleep is the typical micro-sleep operation shown in Fig. 13, and may be for example used in time periods where data transmission is expected to be received by the radio receiver. In the maximum micro-sleep submode, the reception power domain of the radio receiver is turned off immediately after receiving the control channel in the subframe. This submode can thus maximize the micro-sleep duration. The maximum micro-sleep mode may be advantageously be used in time periods where no data transmission is expected by the radio receiver and/or where there is no need for receiving reference signals outside the control channel region of the subframe. For example, the maximum micro-sleep mode could be used within subframes outside the DRX cycle (DRX = discontinued reception). Note that the use of the maximum micro-sleep mode is however not limited to its use in time periods where no data transmission is expected by the radio receiver or where there is no need for receiving reference signals outside the control channel region of the subframe.

[0033] In the reduced micro-sleep submode, the reception power domain of the radio receiver is turned off after receiving the control channel and the last reference signal that the radio receiver is to receive within the given subframe in order to be able to perform one or more reference signal-based tasks. In the example shown in Fig. 14, the radio receiver engaged in reduced micro-sleep submode may choose to use the CSI-RS located in the OFDM symbols 5 and 6 for channel quality measurement, and thus the reception power domain is powered off after the OFDM symbol 6. The reduced micro-sleep submode may be used in time periods where no data is expected to be received by the radio receiver and/or where there is a need for receiving reference signals outside the control channel region.

[0034] In this disclosure a radio receiver may switch from a normal micro-sleep mode to the no-data (maximum) micro-sleep mode, if the number of contiguous received subframes without data exceeds certain threshold. Such threshold testing is one exemplary way of deciding the time period where the radio receiver expects no data transmission and, hence, engages in no-data micro-sleep mode. In addition, the radio receiver may switch from the no- data micro-sleep mode to the normal micro-sleep mode if it detects, upon decoding the control channel of a subframe, that the subframe contains data.

[0035] A first aspect of this disclosure extends this concept, by introducing a reduced micro- sleep submode as another no-data micro-sleep submode. In another second aspect, this disclosure also relates to a switching mechanism between the reduced micro-sleep and maximum micro- sleep submodes.

[0036] A method 200 for saving power in a radio receiver of a device according to the first aspect of this disclosure is exemplarily shown in Fig. 2. The device's radio receiver is assumed to receive a sequence of subframes via a radio channel. The sequence of subframes may be within a period of time in which the radio receiver is not expecting to receive data, but this is not mandatory. The radio receiver can be operated essentially in two submodes of a no- data micro-sleep mode, in which the reception power domain of the radio receiver is turned on for reception for a duration of a first section of a respective subframe of the sequence, and is turned off for a duration of a second section of the respective subframe of the sequence. In other words, the first section of a subframe may be a time period in which the reception power domain is powered on, and the second section of a subframe may be a time period in which the reception power domain is powered off. The no-data micro-sleep mode comprises a reduced micro-sleep submode and a maximum micro-sleep submode. The radio receiver may operate 201 in the reduced micro-sleep submode. Furthermore, the radio receiver may operate in the maximum micro-sleep submode 202. The difference between the two submodes is that the duration of the first section of a given subframe in the maximum micro-sleep submode is equal to or shorter than the first section of a given subframe in the reduced micro-sleep submode. [0037] In an exemplary implementation of the method 200, in the maximum micro-sleep submode, the first section of a respective subframe may be a time period required by the device for receiving a number of consecutive REs (or symbols) of the subframe corresponding to a downlink control channel. For example, in an exemplary implementation of the disclosure, the first section of the subframe received by the radio receiver in the maximum micro-sleep submode may be equal to a time period required by the device for receiving the control channel of the subframe.

[0038] Formulated differently, the first section may also be defined as the sum of the duration for receiving a number of consecutive REs (or modulation symbols) corresponding to the downlink control channel. Considering an exemplary implementation of the disclosure in an ODFM-based mobile communication system, the duration of the first section may be equal to the time period required for receiving the OFDM symbols corresponding to the downlink control channel.

[0039] In another example of the method 200, in the reduced micro-sleep submode, the first section of a respective subframe may correspond to a time period required by the device to receive a number of consecutive REs (or modulation symbols) of the subframe corresponding to a downlink control channel and the reference signals of the subframe used by the device for one or more reference signal-based tasks, e.g. channel estimation, channel measurements, time synchronization, frequency synchronization, and/or beam synchronization. Such reference signal-based tasks are also referred to as RS-based tasks in this disclosure.

[0040] One may assume without losing generality that the RSs are scattered across several REs within a time-frequency array of REs that forms the subframe, as for example noted in connection with Fig. 13. In a further exemplary implementation of the method 200, the first section in the reduced micro-sleep submode may thus have a duration that corresponds to a duration between (and including) the first symbol in the subframe comprising a first RS that the radio receiver may need to receive in order to allow the device to perform RS-based tasks or comprising first symbols of the downlink control channel (whichever is received earlier in time), and the symbol (inclusive) of the subframe carrying the last RS that the radio receiver may need to receive in order to allow the device to perform RS-based tasks or the last symbols of the downlink control channel (whichever is received later in time).

[0041] As RSs may be sent at least partially simultaneously to the downlink control channel (i.e. some of the OFDM symbols the REs of which carry the downlink control channel may also include RSs), for the purpose of the reduced micro-sleep submode, the first section of a subframe may include all symbol durations for signaling the downlink control channel and the one or more additional symbol durations carrying RSs. The first section may form a continuous time period within the subframe, but although this may be the case in most practical implementations of this disclosure, this is not mandatory.

[0042] Assuming that the downlink control channel is transmitted in the first number of symbol durations of a subframe, the first section in the reduced micro-sleep submode may also be defined as a duration that corresponds to the duration between the first symbol of the subframe, and the symbol of the subframe that carries the last RS that the radio receiver may need to receive in order to allow the device to perform RS-based tasks.

[0043] Depending on which RSs are to be received within a given subframe when operating the radio receiver in the reduced micro-sleep submode and depending on the position of these RSs within the time-frequency grid of REs forming the subframe, the first section of the subframe may have different durations within different subframes in which the radio receiver is operated in reduced micro-sleep submode. Formulated differently, in reduced-micro sleep submode, the number of symbols forming the first section of a subframe may (but not necessarily has to) vary between subframes, and is, in any case, equal to or larger than the number of symbols forming the first section in the maximum micro-sleep submode.

[0044] The method 200 may comprise switching between the maximum micro-sleep submode and the reduced micro-sleep submode as indicated by the arrows between the two blocks marked with reference numerals 201 and 202 in Fig. 2. The switching between the two submodes of the no-data micro-sleep mode may for example depend on whether or not the device is to perform one or more RS-based tasks. For example, if the device is to perform a channel measurement in a subframe, e.g. for reporting channel state information (CSI) in the uplink, the device may require to receive some of or all of the RSs that are present within the subframe and the first section of the subframe has to be extended to a duration ensuring reception of all RSs required for the given channel measurement. Hence, the device would switch to the reduced micro-sleep submode in the subframe (if not already operating in this submode).

[0045] A second aspect of the disclosure relates to the switching between different submodes of the no-data micro-sleep mode. For example, the switching between the submodes of the no-data micro-sleep mode may be based on micro-sleep pattern. According to one embodiment of this second aspect, a micro-sleep pattern may be generated, e.g. by a processor of a device. The micro-sleep pattern may for example indicate one or more subframes within a sequence of subframes in which the radio receiver is to be operated in a reduced micro-sleep submode. Furthermore, the radio receiver may be switched, e.g. by a switching unit of the device, between the reduced micro-sleep submode and a maximum micro-sleep submode in accordance with the micro-sleep pattern. Thus switching may be performed on a per-subframe basis.

[0046] The micro-sleep pattern may be for example generated by combining a plurality of sub-patterns, where each of the sub-patterns is indicative of a respective RS configuration within the sequence of subframes. Optionally, the micro-sleep pattern may indicate one or more subframes within a sequence of subframes in which the radio receiver is to be operated in the reduced-micro sleep submode, and one or more subframes within the sequence of subframes in which the radio receiver is to be operated in the maximum micro-sleep submode.

[0047] This second aspect of the disclosure may be readily combined with any embodiment of the first aspect of the disclosure. Note that the second aspect may also be implemented in one or more computer readable media that store instructions that, when executed by a processor of a device, cause the device to perform any of the different embodiments of the second aspect mentioned in this disclosure.

[0048] Another method 300 for saving power in a radio receiver of a device is exemplarily shown in Fig. 3. Method 300 can be considered an optional further improvement of method 200 shown in Fig. 2 related to the first aspect of the disclosure, but also as an implementation of the second aspect of this disclosure outlined herein. A processor or a processing circuitry in the radio receiver of the device may determine 301, e.g. for each subframe to be received, whether or not to receive all or part of one or more RS types in the next subframe for RS -based tasks, such as making one or more channel measurements and/or for radio channel synchronization. If the device determines that RSs in next subframe are required for a RS -based task, the radio receiver is operated 302 in reduced micro-sleep submode for reception of the next subframe. Otherwise, the radio receiver is operated 303 in maximum micro-sleep submode for reception of the next subframe.

[0049] When operating 302 in reduced micro-sleep submode for the reception of the next subframe (or to put it differently, if the device determines to receive certain RSs outside the control channel region within the next subframe), the radio receiver is turned on for a duration required to receive and process the first section of the next subframe comprising REs corresponding to both, a downlink control channel and the RSs for RS-based tasks, and the reception power domain of the radio receiver is turned off for the second section of the next subframe after having received the REs corresponding to the downlink control channel and the RSs. In this case, the radio receiver of the device may thus receive the REs corresponding to a downlink control channel, and the RSs for RS-based tasks (only).

[0050] When operating 303 in maximum micro-sleep mode for the reception of the next subframe (or to put it differently, if the device determines to not receive certain RSs outside the control channel region within the next subframe), the radio receiver is turned on for a duration required to receive and process the first section of the next subframe comprising REs corresponding to a downlink control channel, and the reception power domain of the radio receiver is turned off after having received and processed the REs corresponding to the downlink control channel during the second section of the next subframe. In this case, the radio receiver may thus receive the REs corresponding to a downlink control channel (only).

[0051] The processor or a processing circuitry of the radio receiver in the device may for example determine 301 which one of the no-data micro-sleep submodes is to be used for the reception of respective subframe within a sequence of subframe based on a pattern. For example, the one or more subframes of a sequence of subframes in which the reduced micro- sleep submode is to be used and the one or more subframes of the sequence in which the maximum micro-sleep submode is to be used may be indicated by a pattern. The pattern may for example indicate, for each subframe of the sequence, the duration of the first section during which the radio receiver is to be turned on for reception.

[0052] The pattern could be for example configured using access stratum (AS) signaling. In one example implementation the access stratum signaling is Radio Resource Control (RRC) signaling.

[0053] In a further exemplary implementation, the processor of the device may generate the pattern by combining a plurality of sub-patterns. In one example, each of the sub-patterns may indicate one or more subframes of the sequence in which the reduced micro-sleep submode is to be used and the one or more subframes of the sequence in which the maximum micro-sleep submode is to be used. In another example, each of the sub-patterns (further) indicates, for each subframe of the sequence, the duration of the first section during which the reception power domain of the radio receiver is to be turned on. [0054] Optionally, the pattern could also further indicate the subframes in which a normal micro-sleep mode and/or a continuous reception mode is to be used. In normal micro-sleep mode, the reception power domain of the radio receiver is turned off for the rest of the subframe after decoding the control channel, only if the control channel indicates that there is no data for the device in the subframe. In continuous reception mode, the radio receiver is turned on for reception of an entire subframe including the first section and the second section of REs/symbols. Since normal micro-sleep mode may be considered to include the continuous reception mode as a submode and the normal micro-sleep mode supports data reception, it is used as the reference micro-sleep behavior in this disclosure. That is, when normal micro- sleep mode is referred to, it implicitly includes continuous reception mode as well.

[0055] Generally, in the different embodiments described herein, the second period of a subframe may thus correspond to the remainder of the subframe, i.e. the REs not belonging to the first section. Revisiting the above ODFM-based exemplary implementation of method 200 discussed herein above, the second section may comprise all OFDM symbols other than those belonging to the first section. In one exemplary implementation, the second period of the subframe may have different phases.

[0056] For example, the second period may comprise a radio receiver turn-off phase, which may be a transitional period for the radio receiver to power down the circuit block(s) belonging to the reception power domain of the radio receiver. The second phase may comprise a power down phase (also referred to as stable low-power state) in which circuit block(s) of the radio receiver's reception power domain are in a stable low-power state to minimize power consumption. Furthermore, the second period may have a radio receiver turn- on phase, which is a transitional period for the radio receiver to power on circuit block(s) of the reception power domain for reception. The difference between the maximum micro-sleep submode and the reduced micro-sleep submode may thus also be expressed as the difference in the duration of the power down phase, where the reception power domain of the radio receiver is in a stable low-power state. Such power down phase in the maximum micro-sleep submode is usually longer than the power down phase in the reduced micro-sleep mode but this is not mandatory. Depending on the RS location in the subframe, it may also happen that the durations of the power down phase in both submodes are equal.

[0057] Another embodiment relates to a device, e.g. a mobile device. The device comprises a radio receiver that is to receive a sequence of subframes via a radio channel. Furthermore, the device comprises a control unit that is to operate the radio receiver in a no-data micro-sleep mode, in which a reception power domain of the radio receiver is turned on for reception for a duration of a first section of a respective subframe of the sequence, and is turned off for a duration of a second section of the respective subframe of the sequence. For example, the control unit may be implemented within the radio receiver. The control unit may comprise some processing resources and may be implemented by means of a processing circuitry or processor. As in the previous embodiments, the no-data micro-sleep mode comprises a reduced micro-sleep submode and a maximum micro-sleep submode. The duration of the first section of a given subframe in the maximum micro-sleep submode is equal to or shorter than the first section of a given subframe in the reduced micro-sleep submode. Optionally, there may be also normal micro-sleep mode in addition to the no-data micro-sleep mode.

[0058] In a further embodiment the control unit may cause the radio receiver to switch between the maximum micro-sleep submode and the reduced micro-sleep submode for receiving subframes, based on whether or not the device is to perform one or more RS-based tasks based on signals outside the control channel region. Such RS-based tasks may include channel measurements and time, frequency, and/or beam synchronization.

[0059] The control unit of the device may further determine whether or not to receive reference signals in a next subframe in the sequence for RS-based tasks. If the device determines to not receive the RSs within the next subframe, the device turns on the reception power domain of the radio receiver for a duration required to receive the REs corresponding to a downlink control channel that form the first section of the next subframe, and may turn off the radio receiver during the second section of the next subframe, after having received the REs corresponding to the downlink control channel. In another exemplary embodiment, the radio receiver is to receive the REs corresponding to a downlink control channel only, if the device determines to not receive the RSs within the next subframe.

[0060] If the device's control unit determines to receive the RSs within the next subframe, the reception power domain of the radio receiver may be turned on for a duration required to receive the first section of the next subframe comprising REs corresponding to both, a downlink control channel and the RSs for performing one or more RS-based tasks. The reception power domain of the radio receiver may be turned off for the second section of the next subframe after having received the REs corresponding to the downlink control channel and the RSs. [0061] According to another embodiment, the control unit determines the one or more subframes of the sequence in which the reduced micro-sleep submode is to be used and the one or more subframes of the sequence in which the maximum micro-sleep submode is to be used based on a pattern. For example, as noted above, the radio receiver may for example construct the pattern based on information received via access stratum signaling.

[0062] The device according to another embodiment comprises a processor that generates the pattern by combining a plurality of sub-patterns. For example, each of the sub-patterns may indicate one or more subframes of the sequence in which the reduced micro-sleep submode is to be used and the one or more subframes of the sequence in which the maximum micro-sleep submode is to be used. Optionally, the pattern may also indicate one or more subframes within the sequence in which the normal micro-sleep mode and/or a continuous reception mode is to be used. Further or alternatively, each sub-pattern may indicate, for each subframe of the sequence, the duration of the first section during which the radio receiver is to be turned on for reception.

[0063] In a device according to another embodiment, the radio receiver is to detect within the first section of a subframe, while operating in a no-data micro-sleep mode, scheduling information in a downlink control channel indicative of the presence of downlink data for reception by the radio receiver in the second section of the respective subframe and/or within one or more of the next subframes of the sequence; and the control unit is to switch from the no-data micro-sleep mode to normal micro-sleep mode or continuous reception mode. The radio receiver may further receive a retransmission of the downlink data. Optionally, the device may also comprise a radio transmitter that transmits a negative acknowledgment (NACK) for the downlink data in response to detecting the scheduling information.

[0064] A further embodiment of the invention relates to one or more (non-transitory) computer-readable media storing instructions that, when executed by a processor of a device, cause a radio receiver of the device that is to receive a sequence of subframes via a radio channel to save power by operating the radio receiver in a no-data micro-sleep mode, in which a reception power domain of the radio receiver is turned on for reception for a duration of a first section of a respective subframe of the sequence, and is turned off for a duration of a second section of the respective subframe of the sequence. The no-data micro-sleep mode comprises a reduced micro-sleep submode and a maximum micro-sleep submode, and the duration of the first section of a given subframe in the maximum micro-sleep submode is equal to or shorter than the first section of a given subframe in the reduced micro-sleep submode.

[0065] The one or more computer-readable media according to another embodiment, further store instructions that, when executed by the processor of the device, cause the device to perform the steps of the method for reducing power consumption according to one of the different embodiments and implementations discussed herein.

[0066] Figs. 4 and 5 schematically illustrate exemplary time-frequency grids of REs forming a subframe of a radio channel. The REs are indicated by rectangles within Figs. 4 and 5, where "special" REs within the array are marked and explained in the legend at the bottom of Figs. 4 and 5. For exemplary purposes only, the subframe structure of Figs. 4 and 5 has n REs (that may also be referred to as resource elements (REs)) in the time domain and m REs in the frequency domain.

[0067] In Figs. 4 and 5, n = 14 for exemplary purposes only, but more generally n £ [10,11,12, ... ,16], for example. The sub-fame duration T _SF may be for example 1ms, 2ms, etc. Each column of REs within the array may be referred to as an OFDM symbol, or symbol for short. Accordingly the symbol duration T _symbo i is thus equivalent to T _symbo i = T _SF /n.

[0068] The number of REs m in the frequency domain corresponds to the number of subbands N _BW . The number of subbands N _BW may depend on the radio channel bandwidth BW _channel , and the bandwidth of the subbands BW _subband . Accordingly, N _BW =

B W ianne i / B W _{subb and} .

[0069] The time-frequency grid shown in Figs. 4 and 5 may be for example representing a subframe of a radio channel within an OFDM-based mobile communication system. In this case a symbol formed by a respective column of modulation systems may also be referred to as an OFDM symbol. Hence, an OFDM symbol corresponds to m— N _BW REs that are transmitted simultaneously via the radio channel and has a OFDM symbol duration of Tsymboi ⁼ At the bottom of Figs. 4 and 5, the bolder rectangles below the continuous line highlights the - in this example - 14 symbols (e.g. OFDM symbols) of the subframe.

[0070] Turning to Fig. 4, the downlink control channel, e.g. PDCCH, may be sent within REs of the first three symbols #0 to #2. Note that it is possible that the downlink control channel spans less or more symbols, e.g. 4 symbols, such as symbols #0 to #3. Furthermore, RSs for one or more RS-based tasks may be present within REs of symbols #1, #4 and #7. [0071] In the maximum micro-sleep submode, the reception power domain of the radio receiver would be turned on for the first section that spans symbols #0 to #2, and could be turned off from symbols #3 to #13 forming the second section of the subframe. In the reduced micro-sleep submode, the reception power domain of the radio receiver would thus be turned on for the first section that spans symbols #0 to #7, whereas the reception power domain of the radio receiver can be turned off from symbols #8 to #13 forming the second section of the subframe.

[0072] As highlighted in the example of Fig. 5, the downlink control channel may not necessarily be transmitted within the first symbols, but may also be located in the middle (or also the end) of the subframe, e.g. in symbols #6, #7 and #8. Again, RSs for one or more RS- based tasks may be present within REs of symbols #1, #4 and #7. During the maximum micro-sleep submode, the second section of the subframe during which the reception power domain of the radio receiver of the device is turned off may be split in two parts within a single subframe. Whether the reception power domain of the radio receiver can be turned off prior to reception of the symbols #6, #7 and #8 for reception of the downlinlc control channel and thus whether the second section is split in two parts as shown in Fig. 5 may depend on different factors, as will be outlined in further detail below. In the reduced micro-sleep submode, the first section of the subframe may span from symbols #1 to #8, while the second section of the subframe during which the reception power domain of the radio receiver is turned on is indicated as comprising the symbols #0 and #9 to #13.

[0073] Assuming just for exemplary purposes that the duration of the number of symbols during which no symbol is to be received (e.g. the second section of symbols #9 to #13 in Fig. 5) is smaller than the sum of durations of the radio receiver turn-off phase and radio receiver turn-on phase, the reception power domain of the radio receiver could not be powered down, as it has to be turned on before entering into power down phase. Yet, assuming that subframes having an exemplary structure as shown in one of Figs. 4 and 5 are consecutively repeated on a radio channel, the second section may also considered to span across the boundaries of subframes, as indicated by dotted rectangles to the left and right of symbols #0 to #13 of Figs. 5. As indicated by the dotted arrows of the second sections for the two micro-sleep submodes, when extending the second section into the next subframe, the number of symbols during which no symbols is to be received (e.g. Fig. 5: symbols #9 to #13 and symbol #0 of the next subframe for the reduced micro-sleep submode, and symbols #9 to #13 and symbols #0 to #5 in the next subframe for the maximum micro-sleep submode) is high enough to turn-off the reception power domain of the radio receiver such that it can enter into a stable low-power state.

[0074] Fig. 6 illustrates a timing of a 3 GPP LTE subframe according to a conventional 3 GPP LTE standard. The 3 GPP LTE subframe may be received as a radio subframe by the method 200 described above with respect to Fig. 2 or may be received as an LTE subframe by the method 300 described above with respect to Fig. 3.

[0075] In LTE a 1 ms downlink radio subframe 600 consists of 14 OFDM symbols (with normal cyclic prefix). The PDCCH (Physical Downlink Control Channel) is transmitted in the first symbols of a subframe and carries Downlink Control Information (DCI). The exact number of OFDM symbols carrying the PDCCH may be dynamically selected by the eNodeB. The number of OFDM symbols carrying the PDCCH may be signaled by the eNodeB in the PCFICH (Physical Control Format Indicator Channel) comprised within the subframe. For a cell bandwidth BW≥ 3 MHz the PDCCH may be transmitted in the first up to 3 OFDM symbols #0 to #2. For a cell bandwidth BW = 1.4 MHz the PDCCH may be transmitted in the first up to 4 OFDM symbols #0 to #3, respectively. The following, remaining symbols of the subframe may contain the PDSCH (Physical Downlink Shared Channel) which carries user data and higher layer control plane messages. Note that RSs may be present in the PDCCH region and/or PDSCH region.

[0076] The Downlink Control Information (DCI) on the PDCCH may include downlink (DL) grant information. The DL grant is a scheduling grant which indicates that there is data for the UE in the following PDSCH symbols of the subframe. Note that in a more generic implementation, a scheduling grant may also indicate that there is data for the UE in the PDSCH symbols of another subsequent subframe.

[0077] The sequence of PDCCH and PDSCH as exemplarily shown in Fig. 6 may allow the UE to save power by turning off the reception power domain of the radio receiver during the PDSCH region when using the maximum micro-sleep submode. Note that it may be possible to turn off/on individual components of the reception power domain of the radio receiver individually, e.g. the analog subdomain and digital subdomain. Turning off the reception power domain may be of particular relevance for power saving in RRC connected mode, where the UE is supposed to continuously monitor the PDCCH (except for connected mode DRX (Discontinuous Reception)). [0078] Furthermore, in some subframes, some REs within the PDSCH region may carry RSs, such as the cell-specific RS (CRS), UE-specific RS (DM-RS), CSI-RS, etc. The UE may be configured to perform RS-based tasks, such as for example reporting channel measurements in the uplink (UL) on demand or periodically, and thus the UE may need to receive RSs in one or more subframes ahead the subframe in which channel quality reporting should occur. Furthermore, the UE may also require to receive some RSs for synchronization from time to time, and thus the pilot symbols that may also be located in the PDSCH region may need to be received in some of the subframes. Hence, in determining which micro-sleep mode to use for a given subframe, the UE may consider whether or not particular RSs outside the PDCCH region are required or not. If RSs outside the PDCCH region are to be received, the UE may use the reduced micro-sleeps submode to assure reception of the RS(s).

[0079] As shown in Fig. 6, if a processor in the UE determines to operate in maximum micro- sleep submode for a given subframe, the UE may only receive the PDCCH of the subframe within approx. 215 με (equivalent to 3 OFDM symbols of a 1 ms subframe having 14 OFDM symbols in total). Hence, in the maximum micro-sleep submode the first section of the subframe during which the reception power domain is turned on may have a duration of approx. 215 μΞ in this example. The second section of the subframe may thus have a duration of approx. 785 με.

[0080] The second section of the subframe during which the reception power domain is turned off may comprise several subphases. For example, it may be further assumed that the UE requires a radio receiver turn-off phase of another approx. 150 μΞ for signaling from the processor to the radio receiver by means of providing turn-off signal(s) to the components that are part of the reception power domain of the radio receiver, in response to which the reception power domain component(s) enter(s) into a power down state. Furthermore, it is assumed that there is also a turn-on phase of e.g. approx. 100 με required to allow the processor to turn-on the reception power domain component(s) of the radio receiver for reception of the next subframe. Hence, as exemplarily shown in Fig. 6, when assuming a subframe duration of 1 ms, the radio receiver can be powered down for approx. 535 of the subframe, which corresponds to a power saving of approx. 53,5%.

[0081] In case the processor of the UE determines that there are RSs to be perceived in the next subframe, the processor may determine to use a reduced micro-sleep submode for the next subframe. For exemplary purposes, the last RS(s) may be located within OFDM symbol #6 shown in Fig. 6 (for example, the UE may want to receive the RS type 2 shown in Fig. 12). In this case, the UE would receive the PDCCH region of the subframe and the RSs including the last RS(s) located within OFDM symbol #6. In the reduced micro-sleep submode, the first section of the subframe is thus 3 OFDM symbol duration longer than that in maximum micro- sleep submode, i.e. has a duration of approx. 429 με. After receipt of OFDM symbol #6 the processor can turn off the component(s) of the radio receiver's reception power domain. As described with respect to the maximum micro-sleep submode, the processor enters the reception power domain into a radio receiver turn-off phase of another approx.150 με, where turn-off signal(s) is/are provided to the radio receiver's reception power domain, and in response to which the radio receiver enters into a power down state. Similar to the maximum micro-sleep submode there is also a turn-on phase of e.g. approx. 100 με required to allow the processor to turn-on the radio receiver's reception power domain for reception of the next subframe. Hence, in this example, the radio receiver can be entered into power down state for approx. 321 με, so that overall a power saving of 32,1% can still be achieved in this example.

[0082] Fig. 7 shows a basic state diagram 700 for switching the operation mode of the radio receiver between a normal mode 701 and no-data micro-sleep mode 702 according to an exemplary embodiment. Instead of dynamically switching the reception power domain of the radio receiver during the PDSCFI region depending on the PDCCH decoding result only, the proposed embodiment switches to micro-sleep mode 702 under certain conditions, where the radio receiver is always turned off after PDCCH reception, i.e. after the number of PDCCH symbols indicated in the PCFICH.

[0083] The following condition 704 may be used to enter the no-data micro-sleep mode 702: In RRC connected mode, in case no DL grant has been received for a threshold number (N _I(UeDL ) of consecutive subframes and there is no pending DL HARQ retransmission (not shown in Fig. 7), the UE enters into no-data micro-sleep mode. Subframes with retransmissions may not be counted in criterion 704, e.g. if there are 4 consecutive idle subframes, followed by a subframe with a retransmission and again 2 consecutive idle subframes this is counted as 6 consecutive idle subframes. The threshold N _Id i _eDL may be configurable. The threshold N _IdleDL may be adapted dynamically according to the DL traffic profile, e.g. depending on the active applications or the traffic history. A typical value for threshold N _IcUeDL may be 10. Other values may be used as well, for example 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, etc. [0084] Once no-data micro-sleep mode 702 is active the UE may further determine whether RSs in a respective subframe to be received next is to be received in order to perform RS- based task, e.g. to obtain channel state information, such as for example a Channel Quality Indicator (CQI), a Precoding Matrix Indicator (PMI), Rank Indication (RI), etc. to be reported in the uplink. In addition or alternatively, the UE may further determine whether one or more RSs are to be received within the next subframe for RS -based tasks. If no such RSs are to be received, the radio receiver's reception power domain can be operated in maximum micro- sleep submode. Otherwise, the radio receiver's reception power domain is operated in reduced micro-sleep submode, so that reception of the RSs is ensured.

[0085] As noted above, in the example of Fig. 6, PDSCH data for the first DL grant will be missed as the radio receiver is turned off in the PDSCH region of the subframe. Since the component(s) of the reception power domain of the radio receiver are turned off in the PDCCH region in case of operating in no-data micro-sleep mode, the UE is aware of a scheduling grant sent on PDCCH (the received signal corresponding to the PDCCH is still decoded by the decoding power domain), but the DL is not received as the reception power domain is turned off in the PDSCH region of the subframe. As soon as this is detected 703, a NACK can be sent from the UE to the eNB for the current HARQ process, and processor of the UE may switch from the no-data micro-sleep mode 702 to the normal mode 701 such that from the next subframe onwards the radio receiver again operates in normal mode 701 where the radio receiver is turned off after the PDCCH symbols only in case there is no DL data for the UE within the subframe.

[0086] In accordance with the first and second aspect of this disclosure, the rules for activating the reduced micro-sleep submode may be represented by a pattern of subframes. Fig. 8 schematically illustrates an exemplary method for power saving in a radio receiver according to a second aspect of the disclosure, where the switching between the no-data micro-sleep mode is using a micro-sleep pattern. This pattern may be referred to as a reduced micro-sleep pattern. The pattern may indicate those subframes in a sequence of multiple subframes in which the reduced micro-sleep mode is to be used. Alternatively, the pattern may indicate for each subframe in a sequence of multiple subframes the micro-sleep submode to be used in the respective subframe (given that micro-sleep mode is used in the respective subframe). [0087] In some exemplary implementations, the reduced micro-sleep pattern may be a union of multiple sub-patterns. The decomposition to sub-patterns may be done with respect to distinct reference signal (RS) configurations within the subframes.

[0088] As shown in Fig. 8, a sub-pattern may be constructed 801 for each RS configuration. A RS configuration may define the subframes containing the RS and the time-frequency position of the RS in a relevant subframe. Several of such sub-patterns may be combined 802 by a processor of the device to form a single reduced micro-sleep pattern.

[0089] Construction of a reduced micro-sleep pattern or sub-patterns based on RS configurations allows reception of reference signals that can be used for desired actions, e.g. channel quality measurements, synchronization, etc. The channel quality measurement may be reported at a later point in time, i.e. a later subframe. Channel quality reporting by means of CSI may be periodic or on demand of a base station (eNodeB). The construction scheme also lends itself well to sub-sampling of RS-containing subframes, such that the desired actions may use a recent, but not necessarily the latest RS, thereby providing a platform for trading-off the degree of power saving with reporting accuracy. A reduced micro-sleep pattern or a sub-pattern may specify the subframes in the reduced micro-sleep submode and the subframes in the maximum micro-sleep submode. The pattern may additionally specify the micro-sleep interval for each subframe in the reduced micro-sleep submode.

[0090] As further shown in Fig. 8, the processor may switch 803 the operation mode of the radio receiver between the reduced micro-sleep submode and the maximum micro-sleep submode according to the final single reduced micro-sleep pattern obtained at step 802.

[0091] The following example description is an illustration of the concept of using a reduced micro-sleep pattern in the context of a user equipment (UE) device with a LTE single-carrier connection in transmission mode (TM) 10. The UE in the no-data micro-sleep mode may further switch 803 between reduced micro-sleep submode and maximum micro-sleep submode in accordance with a reduced-sleep pattern. The reduced-sleep pattern may be a fixed-length string of bits (bitmap). Each bit or a predetermined number of bits of the pattern corresponds to a respective subframe of a sequence of subframes. For example, a bit value of 1 may indicate reduced micro-sleep and the value of 0 may indicate maximum micro-sleep for the given subframe. This reduced-sleep pattern may be constructed by a bit-wise OR operation on multiple sub-patterns of the same length. [0092] Each sub-pattern (sub-bitmap) may correspond to a distinct transmission and interference condition. A CSI report may contain multiple CSIs, each of which is associated with a CSI process and, if CSI sub-frame sets are configured, for each CSI sub-frame set. A CSI process is a unique combination of a CSI-RS configuration and a CSI-IM (channel state information - interference measurement) configuration, and represents a unique configuration of intended and interfering transmitters. A CSI sub-frame set corresponds to a distinct transmit signal configuration at the set of interfering transmitters. Each combination of a CSI- RS or a CSI-IM configuration and a CSI sub-frame set may be viewed as a reference signal configuration. Thus the UE may construct a sub-bitmap for each of these combinations. A bitmap or a sub-bitmap can be characterized by its length and its bit pattern. One or multiple bits may correspond to a subframe. Thus, the length of a sub-bitmap may be set to the maximum period of a CSI-RS/IM configuration, e.g. 80 subframes, or to an integer multiple thereof. The bit pattern may be set according to the occurrence and the position of the given CSI-RS/IM within a given CSI subframe set. Specifically, a group of bits corresponding to a subframe can be set to certain distinct value, e.g. all zeros, if the subframe does not contain the CSI-RS/IM associated with the bit pattern. This indicates that the UE may engage in the maximum micro-sleep submode. In other cases, the respective groups of bits corresponding to a respective one of the subframes can be set to a distinct value or values, if the subframe contains a CSI-RS/IM, where each distinct value denotes a distinct symbol position of the CSI-RS/IM within the subframe. Hence, each of the distinct values may indicate a distinct length of reduced micro-sleep intervals. For further power saving at the cost of reduced accuracy of the associated reporting, these bitmaps may be sub-sampled such that a subset of the subframes where the receiver operates in reduced micro-sleep submode is switched to maximum micro-sleep submode.

[0093] Fig. 9 illustrates the construction of a micro-sleep for an example TM 10 scenario in LTE. In this simplified example, a 40-bit micro-sleep pattern of 20-subframe periodicity is constructed, considering three CSI-RS/IM configurations.

[0094] The first CSI-RS (or IM) configuration has subframe periodicity of 5, a subframe offset of 1, and occupies ODFM symbols {5, 6}. The second CSI-RS configuration has subframe periodicity of 5, a subframe offset of 2, and occupies OFDM symbols {9, 10}. The third CSI-RS configuration has subframe periodicity of 10, a subframe offset of 4, and occupies OFDM symbols {5, 6}. [0095] In the Fig. 10, bit string '00' denotes maximum micro-sleep, bit string '01 ' denotes reduced micro-sleep submode starting after OFDM symbol 6, and bit string '10' denotes reduced micro-sleep submode starting after OFDM symbol 10. Sub-bitmap 0 activates reduced micro-sleep submode for all subframes with first CSI-RS, while sub-bitmaps 1 and 2 activate reduced micro-sleep submode for subframes with second and third CSI-RS configurations, respectively. The final micro-sleep pattern is a combination of the three sub- bitmaps.

[0096] Similar decompositions of a micro-sleep pattern into multiple sub-patterns can be constructed for other transmission modes (TMs) and/or in other wireless communication systems.

[0097] Fig. 10 shows an exemplary mobile device that incorporates the principles of this disclosure. Mobile device may comprise one or more antennas and/or one or more antenna arrays 1005. Antenna arrays may be useful when implementing an embodiment in a wireless communication system that supported MIMO. Furthermore, the mobile device comprises a radio receiver 1001 coupled to the antenna(s) and/or antenna array(s) 1005 to receive signals. The radio receiver 1001 may be implemented by means of a dedicated receiver circuitry on an integrated circuit, optionally, together with at least some parts of the radio transmitter 1002. The radio receiver 1001 's operation mode may be controlled by processor(s) 1104, so as to switch the radio receiver 1001 mode between the different micro-sleep submodes for example in connection with Figs. 2 to 6 or Fig. 8. The radio receiver 1001 may be further switched between normal micro-sleep mode and no-data micro-sleep mode as explained for example in connection with Figs. 7 and 8.

[0098] The radio receiver 1001 may further comprise reception power domain 1010 and a decoding power domain 1011. The reception power domain 1010 may for example comprise circuit blocks that facilitate one or more of the following functions: low-noise amplification, frequency down-conversion, analog-to-digital conversion, gain (signal level) control, RF impairment estimation and compensation, frequency synchronization, time synchronization, antenna beam synchronization, and FFT (fast Fourier transform). In another example, the reception power domain may be further partitioned into an analog reception power domain and a digital reception power domain (not shown in Fig. 10), to better reflect different electrical characteristics of analog and digital circuit components. The decoding power domain 1011 may for example comprise circuit blocks that facilitate one or more of the following functions: channel estimation, demapping and demodulation, channel decoding (error correction), HARQ (hybrid automatic repeat request) combining, and channel state information estimation.

[0099] The circuit blocks of the reception power domain 1010 and circuit blocks of the decoding power domain 1011 may be at least in part coupled to each other so as to pass signals received via the antenna(s) and/or antenna array(s) 1105 to the circuit blocks of the reception power domain 1010 and from there to the circuit blocks of the decoding power domain 1011 for processing the signals. The reception power domain 1010 of the radio receiver 1101 may for example receive analog signals corresponding to respective subframes under control of processor 1004. The radio receiver 1001 may have also some processing functionality, e.g. may include a processor. The processing functionality is part of decoding power domain 1011 of the radio receiver 1001. For example, the decoding power domain 1011 of the radio receiver 1001 may comprise a demodulation component for demodulation of (soft) symbols received by the analog components 1010 and decoding component to decode the demodulated symbols of the received signals. The power supply of the circuit blocks of the reception power domain 1010 and optionally also the decoding power domain 1011 may be individually controlled by processor(s) 1004, so as to independently switch on and off the one or more blocks of circuitry forming of the reception power domain 1010, and optionally independently switch on and off the one or more blocks of circuitry forming the decoding power domain 1011.

[0100] Similarly, the radio transmitter 1002 of the mobile device is also coupled to the antenna(s) and/or antenna array(s) 1004 and transmits data, such as the channel state information reported by the mobile device. The radio transmitter 1002 may also have a transmission power domain and encoding power domain, similar to the radio receiver 1001 structure. The radio transmitter 1002 may have also some processing functionality, e.g. a processor. For example, the radio transmitter's encoding power domain may comprise a coding component and a modulation component to encode transmission data and to modulate the encoded data to REs of a subframe for transmission. The radio transmitter's transmission power domain may include one or more of frequency up-conversion, digital-to-analog conversion, gain (signal level) control, antenna beam synchronization, and IFFT (inverse fast Fourier transform). Note that the radio receiver 1001 and radio transmitter 1002 may also be combined into a transceiver component. The transceiver component may be formed by an integrated circuit. The integrated circuit may have different blocks of circuitry the power supply of which can be controlled independently. [0101] The mobile device also comprises one or more processors 1004. The processor(s) 1004 may be provided separately from other components, or may be partly incorporated therein. The processor(s) 1004 may for example react on instructions that are stored in memory 1003 and cause the mobile device to perform the procedures as outlined in connection with the embodiments of Figs. 2 to 9. For example, the processor(s) 1004 may execute instructions that allow the mobile device to perform a method for saving power according to any aspect and any embodiment thereof discussed in this disclosure.

[0102] The various embodiments may also be performed or embodied by a combination of computing devices (processors) and software programs providing the desired functionality stored on any kind of computer readable storage media, for example RAM, EPROM, EEPROM, flash memory, registers, hard disks, CD-ROM, DVD, etc. One or more computer readable storage media may be used to store a sequence of instructions that when executed by a device that includes comprising a computing device or processor to perform one of the various embodiments thereof described herein.

[0103] It should be further noted that the individual features of the different embodiments of may individually or in arbitrary combination be subject matter to another embodiment encompassed by this disclosure.

[0104] Having thus described various embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the embodiments may be employed without a corresponding use of the other features.

Additional Examples

[0105] Example 1 provides a method for saving power in a radio receiver of a device that is to receive a sequence of subframes via a radio channel, the method comprising: operating the radio receiver in a no-data micro-sleep mode, in which a reception power domain of the radio receiver is turned on for reception for a duration of a first section of a respective subframe of the sequence, and is turned off for a duration of a second section of the respective subframe of the sequence, wherein said no-data micro-sleep mode comprises a reduced micro-sleep submode and a maximum micro-sleep submode, and wherein the duration of the first section of a given subframe in the maximum micro-sleep submode is shorter than the first section of a given subframe in the reduced micro-sleep submode.

[0106] Example 2 is an optional improvement of Example 1, in which, in the maximum micro-sleep submode, the first section of a respective subframe is a time period required by the device for receiving a number of consecutive modulation symbols of the subframe corresponding to a downlink control channel.

[0107] Example 3 is an optional improvement of Example 1 or 2, in which, in the reduced micro-sleep submode, the first section of a respective subframe is a time period required by the device for receiving a number of consecutive modulation symbols of the subframe corresponding to a downlink control channel and to one or more reference signals for one or more reference signal-based tasks.

[0108] Example 4 is an optional improvement of one of Examples 1 to 3, in which the method further comprises switching between the maximum micro- sleep submode and the reduced micro-sleep submode depending on whether or not the device is to perform reference signal- based tasks.

[0109] Example 5 is an optional improvement of one of Examples 1 to 4, in which the method further comprises determining by the device whether or not to receive one or more reference signals in a next subframe in the sequence for performing one or more reference signal-based tasks.

[0110] Example 6 is an optional improvement of Example 5 in which the method further comprises, in case the device determines not to receive the one or more reference signals within the next subframe, turning on the reception power domain of the radio receiver for a duration required to receive the first section of the next subframe comprising modulation symbols corresponding to a downlink control channel, and turning off the reception power domain of the radio receiver after having received said modulation symbols corresponding to the downlink control channel during the second section of the next subframe.

[0111] Example 7 is an optional improvement of one of Examples 5 or 6, in which the method further comprises in case the device determines to receive the one or more reference signals within the next subframe, turning on the reception power domain of the radio receiver for a duration required to receive the first section of the next subframe comprising modulation symbols corresponding to both, a downlink control channel and the one or more reference signals, and turning off the reception power domain of the radio receiver for the second section of the next subframe after having received said modulation symbols corresponding to the downlink control channel and said one or more reference signals.

[0112] Example 8 is an optional improvement of Example 7, in which the method further comprises in case the device determines to receive the one or more reference signals within the next subframe, receiving said modulation symbols corresponding to a downlink control channel, and receiving said one or more reference signals for performing one or more reference signal-based tasks.

[0113] Example 9 is an optional improvement of one of Examples 1 to 8, in which one or more subframes of said sequence in which the reduced micro-sleep submode is to be used and one or more subframes of said sequence in which the maximum micro-sleep submode is to be used is indicated by a pattern.

[0114] Example 10 is an optional improvement of Example 9, in which the pattern indicates, for each subframe of the sequence, the duration of the first section during which the reception power domain of the radio receiver is to be turned on for reception.

[0115] Example 11 is an optional improvement of Example 9 or 10, further comprising configuring the pattern using access stratum signalling.

[0116] Example 12 is an optional improvement of one of Examples 9 to 11, in which the method further comprises generating the pattern by combining a plurality of sub-patterns, each of which indicates one or more subframes of said sequence in which the reduced micro- sleep submode is to be used and the one or more subframes of said sequence in which the maximum micro-sleep submode is to be used.

[0117] Example 13 is an optional improvement of Example 12, in which the method further comprises generating the pattern by combining a plurality of sub-patterns.

[0118] Example 14 is an optional improvement of Example 12 or 13, in which each sub- pattern indicates, for each subframe of the sequence, the duration of the first section during which the reception power domain of the radio receiver is to be turned on for reception.

[0119] Example 15 is an optional improvement of one of Examples 1 to 14, in which the second period comprises a radio receiver turn-off phase, which is a transitional period for the radio receiver to power down the radio receiver's reception power domain, a power down phase in which the radio receiver's reception power domain is in a stable low-power state, and a radio receiver turn-on phase, which is a transitional period for the radio receiver to power on the radio receiver's reception power domain for reception.

[0120] Example 16 is an optional improvement of one of Examples 1 to 15, in which the method further comprises: while in the no-data micro-sleep mode, detecting within the first section of a subframe scheduling information of a downlink control channel indicative of the presence of downlink data for reception by the radio receiver in the second section of the respective subframe and/or within one or more of the next subframes of the sequence; and switching from the no-data micro-sleep mode to a normal micro-sleep mode or a continuous reception mode; and receiving a retransmission of the downlink data.

[0121] Example 17 is an optional improvement of Example 16, in which the method further comprises transmitting a negative acknowledgement (NACK) in response to detecting the scheduling information.

[0122] Example 18 is an optional improvement of one of Examples 1 to 17, in which the reception power domain comprises active analog components; and wherein the method further comprises: when operating the radio receiver in the no-data micro-sleep mode, turning off the active analog components for the second section of the subframe.

[0123] Example 19 is an optional improvement of Example 18, in which active analog components are turned-off immediately after having received the last modulation symbols of the first section of the respective subframe.

[0124] Example 20 is an optional improvement of one of Examples 18 or 19, in which the reception power domain further comprises digital components; and wherein the method further comprises: when operating the radio receiver in the no-data micro-sleep mode, turning off the digital components for the second section of the subframe.

[0125] Example 21 is an optional improvement of Example 20, in which the digital components are turned-off immediately after having received the last modulation symbols of the first section of the respective subframe.

[0126] Example 22 provides a device comprising: a radio receiver adapted to receive a sequence of subframes via a radio channel; and a control unit adapted to operate the radio receiver in a no-data micro-sleep mode, in which a reception power domain of the radio receiver is turned on for reception for a duration of a first section of a respective subframe of the sequence, and is turned off for a duration of a second section of the respective subframe of the sequence, wherein said no-data micro-sleep mode comprises a reduced micro-sleep submode and a maximum micro-sleep submode, and wherein the duration of the first section of a given subframe in the maximum micro-sleep submode is equal to or shorter than the first section of a given subframe in the reduced micro-sleep submode.

[0127] Example 23 is an optional improvement of Example 22, in which the control unit is adapted to switch between the maximum micro-sleep submode and the reduced micro-sleep submode depending on whether or not the device is to perform one or more reference signal- based tasks.

[0128] Example 24 is an optional improvement of Example 22 or 23, in which the control unit is adapted to determine whether or not to receive one or more reference signals in a next subframe in the sequence for performing one or more reference signal-based tasks.

[0129] Example 25 is an optional improvement of Example 24, in which the control unit is to, if the control unit determines not to receive the one or more reference signals within the next subframe, turn on the reception power domain of the radio receiver for a duration required to receive the first section of the next subframe comprising modulation symbols corresponding to a downlink control channel, and to turn off the reception power domain of the radio receiver after having received said modulation symbols corresponding to the downlink control channel during the second section of the next subframe.

[0130] Example 26 is an optional improvement of Example 24 or 25, in which the radio receiver is adapted to receive the modulation symbols corresponding to a downlink control channel in case the device determines not to receive the one or more reference signals within the next subframe.

[0131] Example 27 is an optional improvement of one of Examples 24 to 26, in which the control unit is adapted to, if the control unit determines to receive the one or more reference signals within the next subframe, turn on the reception power domain of the radio receiver for a duration required to receive the first section of the next subframe comprising modulation symbols corresponding to both, a downlink control channel and the one or more reference signals for performing one or more reference signal-based tasks, and to turn off the reception power domain of the radio receiver for the second section of the next subframe after having received said modulation symbols corresponding to the downlink control channel and said one or more reference signals.

[0132] Example 28 is an optional improvement of Example 27, in which the radio receiver is adapted to receive said modulation symbols corresponding to a downlink control channel carrying and to receive said one or more reference signals for performing one or more reference signal-based tasks, in case the device determines to receive the one or more reference signals within the next subframe.

[0133] Example 29 is an optional improvement of one of Examples 22 to 28, in which the control unit is adapted to determine the one or more subframes of said sequence in which the reduced micro-sleep submode is to be used and the one or more subframes of said sequence in which the maximum micro-sleep submode is to be used based on a pattern.

[0134] Example 30 is an optional improvement of Example 29, in which the pattern indicates, for each subframe of the sequence, the duration of the first section during which the radio receiver is to be turned on for reception.

[0135] Example 31 is an optional improvement of Example 29 or 30, in which the radio receiver is adapted to receive the pattern via access stratum signalling.

[0136] Example 32 is an optional improvement of one of Examples 29 to 31, in which the device further comprises a processing unit to generate the pattern by combining a plurality of sub-patterns, each of which indicates one or more subframes of said sequence in which the reduced micro-sleep submode is to be used and the one or more subframes of said sequence in which the maximum micro-sleep submode is to be used.

[0137] Example 33 is an optional improvement of Example 32, in which the processing unit is adapted to generate the pattern by combining a plurality of sub-patterns.

[0138] Example 34 is an optional improvement of Example 32 or 33, in which each sub- pattern indicates, for each subframe of the sequence, the duration of the first section during which the reception power domain of the radio receiver is to be turned on for reception.

[0139] Example 35 is an optional improvement of one of Examples 22 to 34, in which: the radio receiver is adapted to detect in the first section of a subframe, while in the no-data micro-sleep mode, scheduling information of a downlink control channel indicative of the presence of downlink data for reception by the radio receiver in the second section of the respective subframe and/or within one or more of the next subframes of the sequence; and the control unit is adapted to switch from the no-data micro-sleep mode to a normal micro-sleep mode or a continuous reception mode, wherein in said normal micro-sleep mode the reception power domain of the radio receiver is turned off after decoding the control channel for the rest of the subframe, only if the control channel indicates that there is no data signal in the subframe, and wherein in said in the continuous reception mode the reception power domain of the radio receiver is turned on for reception of an entire subframe including the first section and the second section of modulation symbols; and the radio receiver is adapted to receive a retransmission of the downlink data.

[0140] Example 36 is an optional improvement of Example 35, in which the device further comprises a radio transmitter adapted to transmit a negative acknowledgement (NACK) in response to detecting the scheduling information.

[0141] Example 37 is an optional improvement of one of Examples 22 to 36, in which the reception power domain comprises active analog components; and in which the control unit is adapted to turn off the active analog components for the second section of the subframe, when operating the radio receiver in the no-data micro-sleep mode.

[0142] Example 38 is an optional improvement of Example 37, in which the control unit is adapted to turn-off the active analog components immediately after the analog components of the radio receiver having received the last modulation symbols of the first section of the respective subframe.

[0143] Example 39 is an optional improvement of one of Examples 37 or 38, in which the reception power further comprises digital components; wherein the control unit is adapted to turn off the digital components for the second section of the subframe, when operating the radio receiver in the no-data micro-sleep mode.

[0144] Example 40 is an optional improvement of Example 39, in which the control unit is adapted to turn off the digital analog components immediately after the analog components having received the last modulation symbols of the first section of the respective subframe.

[0145] Example 41 relates to a computer-readable medium storing instructions that, when executed by a processor of a device, cause a radio receiver of the device to receive a sequence of subframes via a radio channel to safe power by: operating the radio receiver in a no-data micro-sleep mode, in which a reception power domain of the radio receiver is turned on for reception for a duration of a first section of a respective subframe of the sequence, and is turned off for a duration of a second section of the respective subframe of the sequence, wherein said no-data micro-sleep mode comprises a reduced micro-sleep submode and a maximum micro-sleep submode, and wherein the duration of the first section of a given subframe in the maximum micro-sleep submode is equal to or shorter than the first section of a given subframe in the reduced micro-sleep submode.

[0146] Example 42 is an optional improvement of Example 41, in which the computer- readable medium stores instructions that, when executed by a processor of a device, cause a radio receiver of the device to receive a sequence of subframes via a radio channel to safe power by performing the steps of the method according to one of Examples 1 to 21.

[0147] Example 43 provides a method comprising: generating a micro-sleep pattern that indicates one or more subframes within a sequence of subframes in which the radio receiver is to be operated in a reduced micro-sleep mode; and switching, on a per-subframe basis, between the reduced micro-sleep submode and a maximum micro-sleep submode in accordance with the micro-sleep pattern.

[0148] Example 44 is an optional improvement of Example 43, in which the method further comprises generating the micro-sleep pattern by combining a plurality of sub-patterns, each of the sub-patterns being indicative of a respective reference signal configuration within the sequence of subframes.

[0149] Example 45 is an optional improvement of Example 43 or 44, in which the micro- sleep pattern indicates one or more subframes within a sequence of subframes in which the radio receiver is to be operated in the reduced-micro sleep mode, and one or more subframes within the sequence of subframes in which the radio receiver is to be operated in the maximum micro-sleep mode.

[0150] Example 46 is an optional improvement of one of Examples 43 to 45, in which the method further comprises the steps of one of Examples 1 to 21.

[0151] Example 47 provides a device comprising: a radio receiver; a processor adapted to generate a micro-sleep pattern indicative of one or more subframes within a sequence of subframes in which the radio receiver is to be operated in a reduced micro-sleep mode; and a switching unit adapted to switch the radio receiver, on a per-subframe basis, between the reduced micro-sleep submode and a maximum micro-sleep submode in accordance with the micro-sleep pattern.

[0152] Example 48 is an optional improvement of Example 47, in which the processor is adapted to generate the micro-sleep pattern by combining a plurality of sub-patterns, each of the sub-patterns being indicative of a respective reference signal configuration within the sequence of subframes.

[0153] Example 49 provides one or more computer-readable media that store instructions that, when executed by a processor of a device, cause the device to: generate a micro-sleep pattern that indicates one or more subframes within a sequence of subframes in which a radio receiver is to be operated in a reduced micro-sleep mode; and switch the radio receiver, on a per-subframe basis, between the reduced micro-sleep submode and a maximum micro-sleep submode in accordance with the micro-sleep pattern.

[0154] Example 50 is an optional improvement of the one or more computer readable media according to Example 49, in which the one or more computer readable media further store instructions that, when executed by the processor of the device, cause the device to generate the micro-sleep pattern by combining a plurality of sub-patterns, each of the sub-patterns being indicative of a respective reference signal configuration within the sequence of subframes.

[0155] Example 51 is an optional improvement of the one or more computer readable media according to Example 49 or 50, in which the one or more computer readable media further store instructions that, when executed by the processor of the device, cause the device to perform the method steps of one of Examples 1 to 21.