Patent Description:
The invention further relates to a method of scheduling transmissions to client devices and a method of transmitting feedback.

The invention also relates to a computer program product enabling a computer system to perform such methods.

Narrowband Internet of Things (NB-loT) has been specified in 3GPP Release <NUM> with the aim to efficiently support loT applications in LTE-based mobile networks with the requirements of deep indoor coverage, low complexity, low cost devices and long device battery life, amongst others.

There are two types of NB-loT carriers specified in 3GPP Release <NUM>, each occupying a bandwidth of <NUM>, the same as one LTE Physical Resource Block (i.e. <NUM> OFDM sub-carriers each with <NUM> width): anchor carriers and non-anchor carriers. An anchor carrier carries all the common control channels for NB-loT (for the delivery of system information, synchronization, etc.). There could be one or more anchor carriers dedicated to NB-loT applications. A non-anchor carrier does not carry the common control channels of NB-loT. In case the in-band operation mode of NB-loT is used, the LTE Physical Resource Block (PRB) of the non-anchor carrier is not dedicated to NB-loT, i.e. it can be shared by NB-loT client devices (a client device is referred to as "User Equipment" or "UE" in LTE) and regular (not NB-loT capable) LTE client devices via PRB resource allocation done by e.g. a joint scheduler.

An idle NB-loT client device camps on an anchor NB-loT carrier and uses it for setting up the connection (i.e. paging and RACH procedure). During the connection set-up process (i.e. when transiting from RRC_ldle to RRC_Connected mode), the NB-loT client device might be allocated an anchor or non-anchor NB-loT carrier for its transmission/reception of data. Typically, an LTE carrier is wideband and the radio propagation condition is frequency-selective. At the exact locations of static client devices, the receive wideband signal may experience a "dip" at some Physical Resource Blocks (assuming the in-band mode operation mode of NB-loT is used), while it might experience much better radio condition at some other PRBs. Typically, each static client device experiences the frequency-selective channel differently: when for one static client device the PRB is in a "dip", the same PRB might have relatively very strong radio channel response for another static client device. For mobile devices, the radio channel quality of particular PRB is varying over time due to its mobility and if a PRB may experience a "dip" this is temporary and changes as the devices move around in the coverage area of the NB-loT system. In LTE, a scheduler assigns frequency and time resources as PRBs to a client device as soon as there is data to transmit by or to the client device. The smallest scheduling time interval is the transmission time interval (TTI). The most advanced resource assignment available in LTE is the so-called 'channel aware' time-frequency scheduling. For the downlink, the scheduler learns the time-frequency fading per client device via channel quality information (CQI) feedback from the client device. Ideally, this feedback is per PRB. For the uplink, the scheduler residing at the base station learns the time-frequency fading per client device via so-called sounding reference signal (SRS) transmission per client device. The SRS is a pilot signal transmitted over the whole frequency band of the LTE carrier (e.g. a <NUM> band) so the scheduler can measure the channel for that client device in each PRB. Based on the time-frequency fading information determined for a client device, the scheduler assigns the PRBs that are 'best' for this client device to this client device. Although 'channel aware' time-frequency scheduling takes the time-frequency fading per client device into account, which frequency resources are used for anchor and non-anchor NB-loT carriers is configured by operators manually. As a result, the frequency-selective radio channels are not taken into account sufficiently. This is especially a problem for static client devices experiencing poor radio conditions (e.g. client devices installed at fixed locations deep in a building), as these client devices may experience unchanged radio conditions during the whole data transmission. <CIT> discloses a system and method for broadband multi-carrier communications. The system includes a base station, user equipment, and a transmission scheme manager. The base station transmits a downlink reference signal. The user equipment receives the downlink reference signal and acquires channel status information from the downlink reference signal for at least one available frequency band within a downlink frequency band. The transmission scheme manager is coupled to the base station and allocates a radio resource to the user equipment based on channel status feedback from the user equipment. The channel status feedback is at least partially based on the channel status information. <CIT> discloses methods and systems for communicating in a wireless communications system utilizing a plurality of frequency bands for downlink (DL) transmission and a plurality of frequency bands for uplink (UL) transmission. In an embodiment, a mobile device receives a DL signal via a DL frequency band. The DL signal contains DL-UL frequency-band association information. The DL signal is decoded to obtain the DL-UL frequency-band association information which is used to determine a UL frequency band for UL transmission. The mobile device configures its radio-frequency (RF) circuitry to operate in the UL frequency band for UL transmission.

Accordingly, aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may all generally be referred to herein as a "circuit", "module" or "system.

<FIG> depicts an environment comprising an embodiment of the system for scheduling transmissions to client devices, base station <NUM> (e.g. an LTE eNodeB), and embodiments of the client devices for transmitting feedback, static client devices <NUM>-<NUM>. In <FIG>, the static client devices <NUM>-<NUM> are located in a building <NUM> and mobile client devices <NUM>-<NUM> are vehicles driving on a road.

The base station <NUM> comprises a transceiver <NUM> and a processor <NUM>, see <FIG>. The processor <NUM> is configured to use the transceiver <NUM> to receive feedback about a plurality of candidate downlink frequency resources from the plurality of static client devices <NUM>-<NUM> and/or measure channel qualities of a plurality of candidate uplink frequency resources from receptions of transmissions by the plurality of static client devices <NUM>-<NUM>. The plurality of static client devices <NUM>-<NUM> comprises one or more active client devices and one or more idle client devices. The processor <NUM> is further configured to select a subset of the plurality of candidate downlink frequency resources and/or a subset of the plurality of candidate uplink frequency resources based on the received feedback and/or the measured channel qualities. The processor <NUM> is further configured to schedule transmissions to the plurality of client devices on the selected subset of candidate downlink frequency resources and/or transmissions from the plurality of static client devices <NUM>-<NUM> on the selected subset of uplink frequency resources. In the embodiment of <FIG>, the base station <NUM> further comprises storage means <NUM>, e.g. for storing the selection/configuration and/or the schedule.

The selected uplink frequency resource(s) and the selected downlink frequency resource(s) may be used as NB-loT anchor carriers, for example. The selected uplink frequency resource(s) and the selected downlink frequency resource(s) may optionally be used as NB-loT non-anchor carriers. Alternatively, the above-mentioned measurements and/or feedback may be re-used or measurements may be performed and feedback may be transmitted in the same manner to determine on which non-anchor carrier(s) to schedule transmissions.

The static client device <NUM> comprises a transceiver <NUM> and a processor <NUM>, see <FIG>. The processor <NUM> is configured to use the transceiver <NUM> to measure at least one channel quality of at least one candidate downlink frequency resource from at least one reception of at least one transmission by the base station <NUM> on the at least one candidate downlink frequency resource. The processor <NUM> is further configured to use the transceiver <NUM> to transmit feedback based on one or more of the at least one measured channel quality to the base station <NUM> on a plurality of candidate uplink frequency resources. The static client devices <NUM>-<NUM> comprise a transceiver and a processor configured as described above. In the embodiment of <FIG>, the static client device <NUM> further comprises a sensor <NUM>. The static client devices <NUM>-<NUM> comprise a similar sensor. These sensors may be smart electricity sensors, for example.

In the embodiment of <FIG>, the processor <NUM> is configured to use the transceiver <NUM> to receive the feedback about the plurality of candidate downlink frequency resources on the plurality of candidate uplink frequency resources and measure the channel quality of the plurality of candidate uplink frequency resources from receptions of the feedback on the plurality of candidate uplink frequency resources.

In the embodiment of <FIG>, the processor <NUM> is configured to use the receiver <NUM> to receive the feedback about at least one candidate downlink frequency resource on the at least one candidate uplink frequency resource paired with the at least one candidate downlink frequency resource, if such a pairing has been specified. The feedback comprises an identification of one or more candidate downlink frequency resources to which the feedback relates when the feedback is transmitted on an unpaired candidate uplink frequency resource.

In accordance with the claims, the processor <NUM> is further configured to determine at least one combined quality for at least one pair of candidate downlink and uplink frequency resources and select a subset of the plurality of candidate downlink frequency resources and a subset of the plurality of candidate uplink frequency resources based on the at least one combined quality if such a pairing has been specified. Separate (e.g. channel) qualities may be used for non-paired candidate downlink and uplink frequency resources. In practice, most likely either all candidate downlink and uplink frequency resources are paired or none of them is paired.

The processor <NUM> is further configured to schedule transmissions to mobile client devices <NUM>-<NUM> on the selected subset of candidate downlink frequency resources and transmissions from the mobile client devices <NUM>-<NUM> on the selected subset of uplink frequency resources. The selected subset of candidate downlink frequency resources is not based on feedback received from the mobile client devices <NUM>-<NUM>. The selected subset of candidate uplink frequency resources is not based on a channel quality measured from a reception of a transmission by the mobile client devices <NUM>-<NUM>.

The processor <NUM> is configured to use the transceiver <NUM> to transmit wireless signals, specifically pilot signals, on the plurality of candidate downlink frequency resources. The processor <NUM> is configured to use the transceiver <NUM> to inform the plurality of static client devices <NUM>-<NUM> of at least one time at which it will start transmitting the wireless signals on the plurality of candidate downlink frequency resources.

In the embodiment shown in <FIG>, the base station <NUM> comprises one processor <NUM>. In an alternative embodiment, the base station <NUM> comprises multiple processors. The processor <NUM> of the base station <NUM> may be a general-purpose processor, e.g. an Intel or an AMD processor, or an application-specific processor, for example. The processor <NUM> may comprise multiple cores, for example. The processor <NUM> may run a Unix-based or Windows operating system, for example. The transceiver <NUM> of the base station <NUM> may use one or more cellular communication technologies such as GPRS, CDMA, UMTS, NB-loT and/or LTE to communicate with the client devices <NUM>-<NUM>, for example. In the embodiment shown in <FIG>, a receiver and a transmitter are combined in the transceiver <NUM> of the base station <NUM>. In an alternative embodiment, the base station <NUM> comprises a receiver and a transmitter that are separate. The storage means <NUM> may comprise solid state memory, e.g. one or more Solid State Disks (SSDs) made out of Flash memory, or one or more hard disks, for example. The base station <NUM> may comprise other components typical for a component in a mobile communication network, e.g. a power supply, or typical for a base station, e.g. an array of antennas. In the embodiment shown in <FIG>, the base station <NUM> comprises one device. In an alternative embodiment, the base station <NUM> comprise multiple devices.

In the embodiment shown in <FIG>, the static client device <NUM> comprises one processor <NUM>. In an alternative embodiment, the static client device <NUM> comprises multiple processors. The processor <NUM> may be a general-purpose processor, e.g. an ARM processor, or an application-specific processor. The processor <NUM> may run a Unix-based operating system, for example. The transceiver <NUM> of the static client device <NUM> may use one or more cellular communication technologies such as e.g. GPRS, CDMA, UMTS, NB-loT (Narrow Band - Internet of Things) and/or LTE to communicate with the base station <NUM>, for example. In the embodiment shown in <FIG>, a receiver and a transmitter are combined in the transceiver <NUM> of the static client device <NUM>. In an alternative embodiment, the static client device <NUM> comprises a receiver and a transmitter that are separate. The sensor <NUM> may comprise one or more cameras and/or one or more microphones, for example. The static client device <NUM> may comprise other components typical for a client device, e.g. a battery.

In the embodiment shown in <FIG>, the system for scheduling transmissions to client devices is a base station. In an alternative embodiment, the system may comprise a base station plus one or more other components/functions of a mobile communication network, e.g. plus a physical or virtual node which schedules transmissions to client devices. The system may comprise multiple base stations distributed over multiple sites or one base station working with multiple distributed antennas at different locations (Remote Radio Head (RRH) concept), for example.

First embodiments of the method of scheduling transmissions to client devices and the method of transmitting feedback are shown in <FIG>. A step <NUM> comprises a client device transmitting pilot signals (e.g. LTE Sounding Reference Signals or pilot signals similar to LTE Sounding Reference Signals) to a base station on a plurality of candidate uplink frequency resources. In the embodiments of <FIG>, the uplink frequency resources are frequency bands allocated as LTE Physical Resource Blocks (PRBs). LTE uses Orthogonal Frequency-Division Multiplexing (OFDM) in which a large number of closely spaced orthogonal subcarrier signals are used to carry data in parallel. In an alternative embodiment, resources may be allocated to users in a different way. In the embodiments of <FIG>, the selected uplink frequency resources are used as NB-loT carriers.

Step <NUM> is carried out in stage <NUM> shown in <FIG>. Stage <NUM> corresponds to time slots <NUM>-<NUM> in <FIG>. Time slots <NUM>-<NUM> are indicated on timeslot bar <NUM>. In time slot <NUM>, static client device UE1 transmits a pilot signal (up1) to the base station on candidate uplink NB-loT carrier <NUM>, static client device UE3 transmits a pilot signal (up3) to the base station on candidate uplink NB-loT carrier <NUM>, and static client device UE2 transmits a pilot signal (up2) to the base station on candidate uplink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits a pilot signal (up2) to the base station on candidate uplink NB-loT carrier <NUM>, UE1 transmits a pilot signal (up1) to the base station on candidate uplink carrier <NUM>, and UE3 transmits a pilot signal (up3) to the base station on candidate uplink NB-loT carrier <NUM>.

In time slot <NUM>, UE3 transmits a pilot signal (up3) to the base station on candidate uplink NB-loT carrier <NUM>, UE1 transmits a pilot signal (up1) to the base station on candidate uplink NB-loT carrier <NUM>, and UE2 transmits a pilot signal (up2) to the base station on candidate uplink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits a pilot signal (up2) to the base station on candidate uplink NB-loT carrier <NUM>, UE3 transmits a pilot signal (up3) to the base station on candidate uplink NB-loT carrier <NUM>, and UE1 transmits a pilot signal (up1) to the base station on candidate uplink NB-loT carrier <NUM>. In the embodiment of <FIG> (and also in the embodiments of <FIG> and <FIG>-<NUM>), UE1 to UE3 do not transmit simultaneously on a single candidate uplink NB-loT carrier. In an alternative embodiment, multiple of the UEs transmit on a single candidate uplink NB-loT carrier simultaneously in at least one time slot. This may be used to reduce the length of stage <NUM> of <FIG> (and stage <NUM> of <FIG> and stage <NUM> of <FIG>).

A step <NUM> comprises the base station receiving the pilot signals from the client device and from further ones of the plurality of client devices. A step <NUM> comprises the base station measuring channel qualities (e.g. pilot signal level) on the plurality of candidate uplink NB-loT carriers from receptions of transmissions of the pilot signals. The plurality of client devices comprises one or more active client devices and/or one or more idle client devices. By analyzing the channel qualities, the base station can estimate if and where the `fade dip' in the uplink is. This `fade dip' may be on different frequency positon between downlink and uplink for the frequency division duplexing (FDD) communication. While for the Time division duplexing (TDD) communication, there is symmetry between downlink and uplink.

A step <NUM> comprises selecting a subset of the plurality of the candidate uplink NB-loT carriers based on the measured channel qualities. Which carriers have been selected may be communicated via a selected/configured downlink carrier. A step <NUM> comprises scheduling transmissions to the plurality of client devices on the manually configured downlink NB-loT carrier(s) and transmissions from the plurality of client devices on the selected subset of uplink NB-loT carriers. Step <NUM> is performed repeatedly for a certain period, e.g. hours, days, weeks, or months, after which steps <NUM> to <NUM> are repeated. Steps <NUM> to <NUM> may be performed at the initial deployment of NB-loT, and optionally repeated afterwards e.g. periodically in order to account for the changes at NB-loT client devices (e.g. deployment of new NB-loT client devices and/or movements of existing NB-loT client devices). Optionally, the periodicity of this scheme may be adapted while the scheme is being performed, e.g. based on an expectation of how quickly there might be (significant) changes at NB-loT client devices.

The scheduled transmissions take place in time slots <NUM>-<NUM> shown in <FIG>. In time slots <NUM>-<NUM>, the base station transmits data (dd1) to UE1 on manually configured downlink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, the base station transmits data (dd3) to UE3 on downlink carrier <NUM>. In time slots <NUM>-<NUM>, the base station transmits data (dd2) to UE2 on downlink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits data (ud2) to the base station on selected uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, UE1 transmits data (ud1) to the base station on selected uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, UE3 transmits data (ud3) to the base station on selected uplink NB-loT carrier <NUM>.

In the embodiment of <FIG> (and also in the embodiments of <FIG> and <FIG>-<NUM>), transmissions to/from UEs are multiplexed in the time domain. In an alternative embodiment, the transmissions to/from UEs are multiplexed in the frequency domain (different subcarriers are used by different UEs), or in both time and frequency domains. In the embodiment of <FIG> (and also in the embodiments of <FIG> and <FIG>-<NUM>), only a single downlink NB-loT carrier and a single uplink NB-loT carrier are used for transmissions to/from UEs. In an alternative embodiment, multiple downlink NB-loT carriers and/or multiple uplink NB-loT carriers are used for transmissions to/from UEs.

Second embodiments of the method of scheduling transmissions to client devices and the method of transmitting feedback are shown in <FIG>. A step <NUM> comprises a base station transmitting pilot signals to a plurality of client devices on a plurality of candidate downlink NB-loT carriers. The plurality of client devices comprises one or more active client devices and/or one or more idle client devices. The pilot signals could be LTE Cell Specific Reference Signals or Narrowband Reference Signals (NRS) as specified for NB-loT, for example.

NB-loT client devices are currently only able to measure one single downlink PRB (i.e. not multiple PRBs at the same time) due to the reception/transmission bandwidth limit of the receiver, e.g. the receiver is simple, because the client device needs to be low cost. The client devices therefore listen on each of the candidate downlink NB-loT carriers in sequence. This procedure introduces some overhead in using radio resource and the time spent, as well as overhead for a client device in measuring and reporting. On the other hand, this procedure typically only happens once per e.g. hour, day, week, or a month, so the overhead is manageable. Furthermore, this procedure could be scheduled at a time when there is little traffic in the network (e.g. at night), in order to mitigate the impact.

Step <NUM> is carried out in stage <NUM> shown in <FIG>. Stage <NUM> corresponds to time slots <NUM>-<NUM> in <FIG>. In time slots <NUM>-<NUM>, the base station transmits a pilot signal (dp) on candidate downlink NB-loT carrier <NUM>, on candidate downlink NB-loT carrier <NUM>, on candidate downlink NB-loT carrier <NUM> and on candidate downlink NB-loT carrier <NUM>. In the embodiment of <FIG> (and also in the embodiments of <FIG>), the pilot signal (dp) is transmitted on all of the candidate downlink NB-loT carriers simultaneously. In an alternative embodiment, the pilot signal (dp) is transmitted on the candidate downlink NB-loT carriers in sequence or according to another schedule. This may result in a more efficient use of resources. The schedule for transmitting the pilot signal (dp) may be standardized or communicated by the base station to the UEs, for example.

A step <NUM> comprises a client device receiving these pilot signals. A step <NUM> comprises the client device measuring at least one channel quality of at least one of the plurality of candidate downlink NB-loT carriers from at least one reception of at least one transmission by the base station on the plurality of candidate downlink NB-loT carriers. A step <NUM> comprises transmitting feedback based on one or more of the at least one measured channel quality to the base station on a single, manually configured uplink NB-loT carrier.

Step <NUM> is carried out in stage <NUM> shown in <FIG>. Stage <NUM> corresponds to time slots <NUM>-<NUM> in <FIG>. In time slot <NUM>, UE1 transmits its feedback (f1) to the base station on manually configured uplink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits its feedback (f2) to the base station on uplink NB-loT carrier <NUM>. In time slot <NUM>, UE3 transmits its feedback (f3) to the base station on uplink NB-loT carrier <NUM>. In the embodiment of <FIG>, illustrated in <FIG>, the feedback identifies which one or more of candidate downlink NB-loT carriers <NUM>-<NUM> is or are preferred by the client device. The period in which stages <NUM> and <NUM> take place may be pre-configured in the base station and in the client devices or communicated by the base station to the client devices, for example. In the embodiment of <FIG>, the feedback transmitted by the UEs is multiplexed in the time domain. In an alternative embodiment, the feedback transmitted by the UEs is multiplexed in the frequency domain (different subcarriers are used by different UEs), or in both time and frequency domains.

A step <NUM> comprises the base station receiving this feedback from the client device and receiving further feedback from the further ones of the plurality of client devices. A step <NUM> comprises selecting a subset of the plurality of candidate downlink NB-loT carriers based on the received feedback. Step <NUM> comprises scheduling transmissions to the plurality of client devices on the selected subset of candidate downlink NB-loT carriers and transmissions from the plurality of client devices on the manually configured uplink NB-loT carrier(s).

The scheduled transmissions take place in time slots <NUM>-<NUM> shown in <FIG>. In time slots <NUM>-<NUM>, the base station transmits data (dd1) to UE1 on selected downlink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, the base station transmits data (dd3) to UE3 on selected downlink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, the base station transmits data (dd2) to UE2 on selected downlink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits data (ud2) to the base station on manually configured uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, UE1 transmits data (ud1) to the base station on manually configured uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, UE3 transmits data (ud3) to the base station on manually configured uplink NB-loT carrier <NUM>.

Third embodiments of the method of scheduling transmissions to client devices and the method of transmitting feedback are shown in <FIG>. Steps <NUM>, <NUM> and <NUM> are the same as in <FIG>. However, step <NUM> of <FIG> has been replaced with a step <NUM> in <FIG>. Step <NUM> comprises transmitting feedback based on one or more of the at least one measured channel quality of at least one of the plurality of candidate downlink NB-loT carriers to the base station on a plurality of candidate uplink NB-loT carriers.

Step <NUM> is carried out in stage <NUM> shown in <FIG>. Stage <NUM> corresponds to time slots <NUM>-<NUM> in <FIG>. In time slot <NUM>, UE1 transmits its feedback relating to candidate downlink carrier <NUM> (f1a) to the base station on candidate uplink NB-loT carrier <NUM>, UE3 transmits its feedback relating to candidate downlink carrier <NUM> (f3b) to the base station on candidate uplink NB-loT carrier <NUM> and UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2c) to the base station on candidate uplink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2a) to the base station on candidate uplink NB-loT carrier <NUM>, UE1 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f1b) to the base station on candidate uplink NB-loT carrier <NUM> and UE3 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f3d) to the base station on candidate uplink NB-loT carrier <NUM>.

In time slot <NUM>, UE3 transmits its feedback relating to candidate downlink carrier <NUM> (f3a) to the base station on candidate uplink NB-loT carrier <NUM>, UE1 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f1c) to the base station on candidate uplink NB-loT carrier <NUM> and UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2d) to the base station on candidate uplink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2b) to the base station on candidate uplink NB-loT carrier <NUM>, UE3 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f3c) to the base station on candidate uplink NB-loT carrier <NUM> and UE1 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f1d) to the base station on candidate uplink NB-loT carrier <NUM>. In the embodiment of <FIG>, illustrated in <FIG>, the feedback comprises the Received Signal Received Power (RSRP) of a single downlink carrier. In an alternative embodiment, the feedback additionally or alternatively comprises other performance metrics like RSRQ, CQI, SNR, SINR.

A step <NUM> comprises the base station receiving the feedback from the client devices on the plurality of candidate uplink NB-loT carriers. A step <NUM> comprises the base station measuring channel qualities on the plurality of candidate uplink NB-loT carriers from receptions of the feedback from the plurality of client devices. A step <NUM> comprises selecting a subset of the plurality of candidate downlink NB-loT carriers and a subset of the plurality of candidate uplink NB-loT carriers based on the received feedback and the measured channel qualities.

Step <NUM> comprises scheduling transmissions to the plurality of client devices on the selected subset of candidate downlink NB-loT carriers and transmissions from the plurality of client devices on the selected subset of candidate uplink NB-loT carriers. In the embodiment of <FIG>, the uplink NB-loT carriers and the downlink NB-loT carriers are paired, i.e. an uplink NB-loT carrier has a pre-defined relative frequency position to the downlink NB-loT carrier (where the base station has transmitted the pilot signal). In this case, the base station implicitly knows for which downlink carrier the feedback received in step <NUM> is.

The scheduled transmissions take place in time slots <NUM>-<NUM> shown in <FIG>. In time slots <NUM>-<NUM>, the base station transmits data (dd1) to UE1 on selected downlink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, the base station transmits data (dd3) to UE3 on selected downlink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, the base station transmits data (dd2) to UE2 on selected downlink NB-loT carrier <NUM>. In time slot <NUM>, UE2 transmits data (ud2) to the base station on selected uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, UE1 transmits data (ud1) to the base station on selected uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM>, UE3 transmits data (ud3) to the base station on selected uplink NB-loT carrier <NUM>.

Fourth embodiments of the method of scheduling transmissions to client devices and the method of transmitting feedback are shown in <FIG>. In these fourth embodiments, the uplink NB-loT carriers and the downlink NB-loT carriers are not paired, i.e. there is no uplink NB-loT carrier that has a one-to-one relation with the downlink carrier where the base station has transmitted the pilot signal. Steps <NUM> to <NUM>, steps <NUM> to <NUM> and step <NUM> are the same as in <FIG>. Step <NUM> of <FIG> has been replaced with step <NUM> of <FIG> and step <NUM> of <FIG>. Since the uplink NB-loT carriers and the downlink NB-loT carriers are not paired, they are selected separately, which may result in better performance. This is illustrated in <FIG>.

The difference between <FIG> and <FIG> is that in <FIG>, candidate uplink NB-loT carrier <NUM> has been selected instead of candidate uplink NB-loT carrier <NUM>. In <FIG>, downlink NB-loT carrier <NUM> is paired with uplink NB-loT carrier <NUM>, downlink carrier <NUM> is paired with uplink NB-loT carrier <NUM>, downlink NB-loT carrier <NUM> is paired with uplink NB-loT carrier <NUM>, and downlink NB-loT carrier <NUM> is paired with uplink NB-loT carrier <NUM>. Thus, the selected downlink NB-loT carrier <NUM> and the selected uplink NB-loT carrier <NUM> of <FIG> are paired and the selected downlink NB-loT carrier <NUM> and the selected uplink NB-loT carrier <NUM> of <FIG><NUM> are not paired.

In time slot <NUM> of <FIG>, UE2 transmits data (ud2) to the base station on selected uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM> of <FIG>, UE1 transmits data (ud1) to the base station on selected uplink NB-loT carrier <NUM>. In time slots <NUM>-<NUM> of <FIG>, UE3 transmits data (ud3) to the base station on selected uplink NB-loT carrier <NUM>. In <FIG>, the feedback transmitted by the client devices in stage <NUM> is the same as in <FIG>. Although the selected downlink NB-loT carrier <NUM> and the selected uplink NB-loT carrier <NUM> are not paired, the pairing between downlink NB-loT carriers and uplink NB-loT carriers is used in stage <NUM> in <FIG>.

In <FIG>, the pairing between downlink NB-loT carriers and uplink NB-loT carriers is not used in stage <NUM>. In <FIG>, the feedback transmitted on an uplink NB-loT carrier does not relate to a paired downlink NB-loT carrier, but identifies to which downlink NB-loT carrier it does relate. Like in <FIG> and <FIG>, the feedback comprises the Received Signal Received Power (RSRP) of a single downlink NB-loT carrier. In an alternative embodiment, the feedback additionally or alternatively comprises other performance metrics like RSRQ, CQI, SNR, SINR.

In time slot <NUM> of <FIG>, UE1 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f1a) to the base station on candidate uplink NB-loT carrier <NUM>, UE3 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f3c) to the base station on candidate uplink NB-loT carrier <NUM> and UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2d) to the base station on candidate uplink NB-loT carrier <NUM>. In time slot <NUM> of <FIG>, UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2b) to the base station on candidate uplink NB-loT carrier <NUM>, UE1 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f1b) to the base station on candidate uplink NB-loT carrier <NUM> and UE3 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f3a) to the base station on candidate uplink NB-loT carrier <NUM>.

In time slot <NUM> of <FIG>, UE3 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f3d) to the base station on candidate uplink NB-loT carrier <NUM>, UE1 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f1c) to the base station on candidate uplink NB-loT carrier <NUM> and UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2a) to the base station on candidate uplink NB-loT carrier <NUM>. In time slot <NUM> of <FIG>, UE2 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f2c) to the base station on candidate uplink NB-loT carrier <NUM>, UE3 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f3b) to the base station on candidate uplink NB-loT carrier <NUM> and UE1 transmits its feedback relating to candidate downlink NB-loT carrier <NUM> (f1d) to the base station on candidate uplink NB-loT carrier <NUM>.

In <FIG>, the feedback transmitted on a candidate uplink NB-loT carrier identifies which one or more of candidate downlink NB-loT carriers <NUM>-<NUM> is or are preferred by the client device, like in <FIG>. However, since feedback should be transmitted on multiple candidate uplink NB-loT carriers, a client device transmits the same feedback on all the candidate uplink NB-loT carriers <NUM>-<NUM>. UE1 transmits its feedback on candidate uplink NB-loT carrier <NUM> in time slot <NUM>, on candidate uplink NB-loT carrier <NUM> in time slot <NUM>, on candidate uplink NB-loT carrier <NUM> in time slot <NUM> and on candidate uplink NB-loT carrier <NUM> in time slot <NUM>.

UE2 transmits its feedback on candidate uplink NB-loT carrier <NUM> in time slot <NUM>, on candidate uplink NB-loT carrier <NUM> in time slot <NUM>, on candidate uplink NB-loT carrier <NUM> in time slot <NUM> and on candidate uplink NB-loT carrier <NUM> in time slot <NUM>. UE3 transmits its feedback on candidate uplink NB-loT carrier <NUM> in time slot <NUM>, on candidate uplink NB-loT carrier <NUM> in time slot <NUM>, on candidate uplink NB-loT carrier <NUM> in time slot <NUM> and on candidate uplink NB-loT carrier <NUM> in time slot <NUM>.

<FIG> and <NUM>-<NUM> show the use of Frequency Division Multiplexing (FDD). In an alternative embodiment, Time Division Multiplexing (TDD) is used. In this alternative embodiment, the same frequency resources are used for both uplink and downlink and downlink and uplink frequency resources thus do not need to be paired.

Step <NUM> of <FIG> and <FIG>, step <NUM> of <FIG> and <FIG>, and step <NUM> of <FIG> at least comprise selecting one or more NB-loT anchor carriers and may optionally comprise selecting one or more NB-loT non-anchor carriers. The base station/network may perform this selection, for example, by first determining for each candidate carrier how many of the client devices can be served on this candidate carrier (e.g. by determining whether a determined RSRP in the downlink or a measured signal strength in the uplink exceeds a certain threshold).

For example, a first candidate downlink carrier may be able to serve <NUM>% of the client devices, a second candidate downlink carrier may be able to serve <NUM>% of the client devices, a third candidate downlink carrier may be able to serve <NUM>% of the client devices, and a fourth candidate downlink carrier may be able to serve <NUM>% of the client devices. A first candidate uplink carrier may be able to serve <NUM>% of the client devices, a second candidate uplink carrier may be able to serve <NUM>% of the client devices, a third candidate uplink carrier may be able to serve <NUM>% of the client devices, and a fourth candidate uplink carrier may be able to serve <NUM>% of the client devices.

A single downlink carrier and/or a single uplink carrier may be selected or multiple downlink carriers and/or multiple uplink carriers may be selected. In the former case, the selected downlink carrier may be the first candidate downlink carrier (serving <NUM>% of the client devices) and/or the selected uplink carrier may be the first candidate uplink carrier (serving <NUM>% of the client devices), for example.

In the latter case, the base station/network may use, for example, one of the following criteria for selecting multiple carriers based on the determined information:.

When determining how many client devices can be served with a candidate downlink carrier, it may be taken into account whether these client devices can be served by the statically configured uplink carriers or candidate uplink carriers. When determining how many client devices can be served with a candidate uplink carrier, it may be taken into account whether these client devices can be served by the statically configured downlink carriers or candidate downlink carriers. For example, the first candidate uplink carrier and the first candidate downlink carrier might together be able to serve <NUM>% of the client devices in both uplink and downlink, while the second candidate downlink carrier and the second candidate uplink carrier might together be able to serve <NUM>% of the client devices in both uplink and downlink. In this case, the latter combination may be preferred.

A combined quality of a paired downlink frequency resource and uplink frequency resource may be determined in one of the following ways, for example:.

The measurements performed in step <NUM> of <FIG> and step <NUM> of <FIG> and <FIG> and the feedback received in steps <NUM> of <FIG> and step <NUM> of <FIG> and <FIG> may be used in step <NUM> to determine which time-frequency resources to allocate to a client device if multiple downlink NB-loT carriers and/or multiple downlink NB-loT have been selected/configured.

In the telecommunications system <NUM> of <FIG>, three generations of networks are schematically depicted together for purposes of brevity. A more detailed description of the architecture and overview can be found in 3GPP Technical Specification TS <NUM> 'Network Architecture' which is included in the present application by reference in its entirety. Other types of cellular telecommunication system can alternatively or additionally be used, e.g. a <NUM> cellular telecommunication system.

The lower branch of <FIG> represents a GSM/GPRS or UMTS network.

For a GSM/GPRS network, a radio access network (RAN) system <NUM> comprises a plurality of nodes, including base stations (combination of a BSC and a BTS), not shown individually in <FIG>. The core network system comprises a Gateway GPRS Support Node <NUM> (GGSN), a Serving GPRS Support Node <NUM> (SGSN, for GPRS) or Mobile Switching Centre (MSC, for GSM, not shown in <FIG>) and a Home Location Register <NUM> (HLR). The HLR <NUM> contains subscription information for user devices <NUM>, e.g. mobile stations MS.

For a UMTS radio access network (UTRAN), the radio access network system <NUM> also comprises a Radio Network Controller (RNC) connected to a plurality of base stations (NodeBs), also not shown individually in <FIG>. In the core network system, the GGSN <NUM> and the SGSN <NUM>/MSC are connected to the HLR <NUM> that contains subscription information of the user devices <NUM>, e.g. user equipment UE.

The upper branch of the telecommunications system in <FIG> represents a next generation network, commonly indicated as Long Term Evolution (LTE) system or Evolved Packet System (EPS).

The radio access network system <NUM> (E-UTRAN), comprises base stations (evolved NodeBs, eNodeBs or eNBs), not shown individually in <FIG>, providing cellular wireless access for a user device <NUM>, e.g. user equipment UE. The core network system comprises a PDN Gateway (P-GW) <NUM> and a Serving Gateway <NUM> (S-GW). The E-UTRAN <NUM> of the EPS is connected to the S-GW <NUM> via a packet network. The S-GW <NUM> is connected to a Home Subscriber Server HSS <NUM> and a Mobility Management Entity MME <NUM> for signalling purposes. The HSS <NUM> includes a subscription profile repository SPR for user devices <NUM>.

For GPRS, UMTS and LTE systems, the core network system is generally connected to a further packet network <NUM>, e.g. the Internet.

Further information of the general architecture of an EPS network can be found in 3GPP Technical Specification TS <NUM> 'GPRS enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access'.

<FIG> depicts a block diagram illustrating an exemplary data processing system that may perform the methods as described with reference to <FIG> and <FIG>.

Examples of input devices may include, but are not limited to, a keyboard, a pointing device such as a mouse, or the like.

In various embodiments, the application <NUM> may be stored in the local memory <NUM>, he one or more bulk storage devices <NUM>, or separate from the local memory and the bulk storage devices.

Claim 1:
A system (<NUM>) for scheduling transmissions to client devices, comprising:
at least one receiver (<NUM>); and
at least one processor (<NUM>) configured to:
- use said at least one receiver (<NUM>) to receive feedback about a plurality of candidate downlink frequency resources from a plurality of client devices (<NUM>-<NUM>) and/or measure channel qualities of a plurality of candidate uplink frequency resources from receptions of transmissions by said plurality of client devices (<NUM>-<NUM>),
- select a subset of said plurality of candidate downlink frequency resources and/or a subset of said plurality of candidate uplink frequency resources based on said received feedback and/or said measured channel qualities, and
- schedule transmissions to said plurality of client devices on said selected subset of candidate downlink frequency resources and/or transmissions from said plurality of client devices (<NUM>-<NUM>) on said selected subset of uplink frequency resources, characterized in that at least one of said plurality of candidate downlink frequency resources is paired with at least one of said plurality of candidate uplink frequency resources and said at least one processor (<NUM>) is configured to determine at least one combined quality for at least one pair of candidate downlink and uplink frequency resources and select a subset of said plurality of candidate downlink frequency resources and a subset of said plurality of candidate uplink frequency resources based on said at least one combined quality.