WO2018202658A1

WO2018202658A1 - Dynamic adaptivity mode

Info

Publication number: WO2018202658A1
Application number: PCT/EP2018/061103
Authority: WO
Inventors: Yusheng Liu; David Sugirtharaj; Emma Wittenmark; Oskar Drugge
Original assignee: Telefonaktiebolaget LM Ericsson AB
Current assignee: Telefonaktiebolaget LM Ericsson AB
Priority date: 2017-05-02
Filing date: 2018-05-02
Publication date: 2018-11-08
Anticipated expiration: 2019-11-02

Abstract

A method of operation of a network node and a corresponding network node are disclosed. The method comprises determining, based on the type of wireless devices that need to be scheduled during the upcoming scheduling interval, a select adaptivity mode for downlink transmissions during the upcoming scheduling interval. The select adaptivity mode is one of a predefined set of adaptivity modes comprising an adaptive mode and a non-adaptive mode. Further the method comprises indicating the select adaptivity mode to one or more wireless devices and performing downlink transmissions using the select adaptivity mode.

Description

DYNAMIC ADAPTIVITY MODE

Background

The Third Generation Partnership Project (3GPP) initiative "License Assisted Access (LAA)" intends to allow Long Term Evolution (LTE) equipment to also operate in the unlicensed radio spectrum such as the 5 gigahertz (GHz) band. The unlicensed spectrum is used as a complement to the licensed spectrum. Accordingly, devices connect in the licensed spectrum (Primary Cell (PCell)) and use Carrier Aggregation (CA) to benefit from additional transmission capacity in the unlicensed spectrum (Secondary Cell (SCell)). To reduce the changes required for aggregating licensed and unlicensed spectrum, the LTE frame timing in the PCell is simultaneously used in the SCell.

In addition to LAA operation, it should be possible to run LTE fully on the unlicensed band without the support from the licensed band. This is called LTE in unlicensed spectrum (LTE-U) standalone.

Regulatory requirements, however, may not permit transmissions in the unlicensed spectrum without prior channel sensing. Since the unlicensed spectrum must be shared with other radios of similar or dissimilar wireless technologies, a so called Listen-Before- Talk (LBT) method should be applied. Today, the unlicensed 2.4 GHz spectrum is mainly used by equipment implementing the IEEE 802.1 1 Wireless Local Area Network (WLAN) standard. This standard is known under its marketing brand "Wi-Fi."

The LBT procedure leads to uncertainty at the enhanced or evolved Node B (eNB) regarding whether it can transmit a downlink subframe(s) or not. This leads to a corresponding uncertainty at the User Equipment device (UE) as to if it has a subframe to decode or not. An analogous uncertainty exists in the uplink direction where the eNB is uncertain if the UEs scheduled on the SCell actually transmitted or not.

For enhanced Machine Type Communication (eMTC) technologies to use the 2.4 GHz spectrum, there are several classifications for compliance, such as the European Standard ETSI EN 300 328 v2.1.1 . The system may be employing frequency hopping or wideband transmissions. To be considered for frequency hopping, the bandwidth must be narrow enough to hop on N individual frequencies within the band. Narrow bandwidth is generally favorable for eMTC operation as it has reduced complexity and power saving for devices. A further advantage is that higher transmit power is allowed since wideband transmissions should comply with a low Power Spectral Density (PSD). The PSD limitation is 10 decibel- milliwatts (dBm) / 1 megahertz (MHz).

Further, equipment/devices can be adaptive or non-adaptive as specified by ETSI EN 300 328 v2.1.1 (e.g. in sections 4.2.2, 4.3.1 .7 and 4.3.2.6). Adaptive mode is there defined as a mode of operation in which an equipment or device can adapt its medium access to its radio environment by identifying other transmissions present in the band. An adaptive equipment or device is an equipment or device that is operating in adaptive mode and then uses an automatic mechanism which allows the equipment to adapt automatically to its radio environment by identifying frequencies that are being used by other equipment. ETSI EN 300 328 v2.1.1 specifies adaptivity for frequency hopping or non-frequency hopping modulation.

For frequency hopping equipment, being adaptive allows a longer continuous transmission (e.g., 60 milliseconds (ms)) versus a shorter on-off transmission of, e.g., 30 ms in total with, e.g., a 5 ms on and 5 ms off burst pattern.

A non-adaptive equipment or device does not use such an automatic mechanism and hence is subject to certain restrictions with respect to using the transmission medium or channel in order to ensure sharing with other equipment. Non-adaptive transmissions are good for coverage enhancement since it would be deterministic and predictable and thus allow repetition at the transmitter and accumulation at the receiver to improve coverage. However, an important drawback of using non-adaptive transmission is an associated limit on the channel medium utilization, i.e. the total transmit time a device is allowed to utilize the channel over a certain defined observation period.

Adaptive transmissions or adaptive mode require Clear Channel Assessment (CCA) to identify other transmissions in the channel before the transmission and, hence, interference from other systems can delay the transmission. Instead of delaying the transmission, another alternative is to adapt a frame-based transmission where, if the CCA fails, the transmission burst is dropped totally and the next scheduled transmission is attempted directly in the next frame. The occasions where such transmissions occur are known to the UE and so the system has deterministic behavior in that sense. Such a scheme is also referred to as frame-based LBT (c.f. section 4.8.3.1 of ETSI EN 301 893 version 1.8.1 ) where the LBT is performed just prior to a frame boundary. If the UE does not detect the transmission, it can save power by going to sleep and waking up for the next occasion. Other LBT schemes such as e.g. a load based LBT (c.f. section 4.8.3.2 of ETSI EN 301 893 version 1.81 ) that allow transmissions to start at any point in time (without following any frame structure) are also possible.

Regulatory requirements allow for adaptive equipment to operate in non-adaptive mode, which indicates that devices are allowed to dynamically switch between adaptive and non- adaptive mode.

Summary

As indicated above, there are pros and cons related to the use of adaptive versus non- adaptive mode for frequency hopping. European regulations indicate that dynamic switching may be allowed. However, existing solutions lack procedures and signaling to coordinate such dynamic behavior.

Embodiments disclosed herein will advantageously enable a more efficient system maximizing the coverage and capacity under the constraints of the regulatory

requirements.

According to one aspect, a method of operation of a network node comprises determining, based on the type of wireless devices that need to be scheduled during the upcoming scheduling interval, a select adaptivity mode for downlink transmissions during the upcoming scheduling interval. The select adaptivity mode is one of a predefined set of adaptivity modes comprising an adaptive mode and a non-adaptive mode. Further the method comprises indicating the select adaptivity mode to one or more wireless devices and performing downlink transmissions using the select adaptivity mode.

According to another aspect, a network node for a cellular communications network is adapted to determine, based on the type of wireless devices that need to be scheduled during an upcoming scheduling interval, a select adaptivity mode for downlink

transmissions during the upcoming scheduling interval. The select adaptivity mode is one of a predefined set of frequency hopping adaptivity modes comprising an adaptive mode and a non-adaptive mode. The network node is further adapted to indicate the select frequency hopping adaptivity mode to one or more wireless devices; and perform downlink transmissions using the select frequency hopping adaptivity mode. Brief Description of the Drawings

The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure, and together with the description serve to explain the principles of the disclosure.

Figure 1 illustrates one example of a cellular communications network in which

embodiments of the present disclosure may be implemented;

Figure 2 illustrates one example of an adaptive frequency hopping solution that may be suitable to include as one of the options in a dynamic scheme;

Figure 3 illustrates one example of a non-adaptive frequency hopping solution;

Figure 4 is a flow chart that illustrates the operation of a network node according to first embodiments of the present disclosure;

Figure 5 is a flow chart that illustrates the operation of a wireless device according to the first embodiments of the present disclosure;

Figure 6 is a flow chart that illustrates the operation of a network node according to a second embodiment of the present disclosure;

Figure 7 illustrates a first example of the second embodiment;

Figure 8 illustrates a second example of the second embodiment;

Figure 9 is a flow chart that illustrates the operation of a network node according to a third embodiment of the present disclosure;

Figure 10 is a flow chart that illustrates the operation of a wireless device according to a third embodiment of the present disclosure;

Figures 1 1 and 12 illustrate example embodiments of a wireless device; and

Figures 13 through 15 illustrate example embodiments of a network node. Detailed Description

The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure. Radio Node: As used herein, a "radio node" is either a radio access node or a wireless device.

Radio Access Node: As used herein, a "radio access node" or "radio network node" is any node in a radio access network of a cellular communications network that operates to wirelessly transmit and/or receive signals. Some examples of a radio access node include, but are not limited to, a base station (e.g., a New Radio (NR) base station (gNB) in a Third Generation Partnership Project (3GPP) Fifth Generation (5G) NR network or an enhanced or evolved Node B (eNB) in a 3GPP Long Term Evolution (LTE) network), a high-power or macro base station, a low-power base station (e.g., a micro base station, a pico base station, a home eNB, or the like), and a relay node.

Core Network Node: As used herein, a "core network node" is any type of node in a core network. Some examples of a core network node include, e.g., a Mobility Management Entity (MME), a Packet Data Network Gateway (P-GW), a Service Capability Exposure Function (SCEF), or the like.

Wireless Device: As used herein, a "wireless device" is any type of device that has access to (i.e., is served by) a cellular communications network by wirelessly transmitting and/or receiving signals to a radio access node(s). Some examples of a wireless device include, but are not limited to, a User Equipment device (UE) in a 3GPP network and a Machine Type Communication (MTC) device.

Network Node: As used herein, a "network node" is any node that is either part of the radio access network or the core network of a cellular communications network/system. Note that the description given herein focuses on a 3GPP cellular communications system and, as such, 3GPP terminology or terminology similar to 3GPP terminology is oftentimes used. However, the concepts disclosed herein are not limited to a 3GPP system.

Note that, in the description herein, reference may be made to the term "cell" however, particularly with respect to 5G NR concepts, beams may be used instead of cells and, as such, it is important to note that the concepts described herein are equally applicable to both cells and beams.

Figure 1 illustrates one example of a cellular communications network 10 in which embodiments of the present disclosure may be implemented. As illustrated, a number of wireless devices 12 (e.g., UEs) wirelessly transmit signals to and receive signals from radio access nodes 14 (e.g., eNBs or gNBs, which is a 5G NR base station), each serving one or more cells 16. The radio access nodes 14 are connected to a core network 18. In some embodiments, at least some of the radio access nodes 14 operate on carrier frequencies in the unlicensed spectrum that are subject to LBT. For example, in some embodiments, at least some of the radio access nodes 14 are MulteFire radio access nodes 14 that provide standalone operation in unlicensed spectrum.

The present disclosure proposes different ways for a radio access node (e.g., eNB) to coordinate dynamic switching of adaptive versus non-adaptive mode through different types of signaling from the radio access node and corresponding procedures for the wireless device (e.g., UE) and the radio access node. When operating in non-adaptive mode, there is a restriction on channel medium utilization that may become limiting as the system gets loaded (with UEs that have data to send or receive). While the limitation on channel medium utilization isn't applicable for adaptive mode, the adaptive mode suffers from a non-deterministic behavior which may limit the potential for repetition over a large number of subframes. Depending on the use-case and deployment, i.e. the coverage and capacity required by the network, the radio access node will either configure wireless devices to use the adaptive or non-adaptive mode. There may also be use-cases where the wireless devices served by the network contains some wireless devices in dire radio conditions requiring the improved coverage offered by the non-adaptive mode, as well as some wireless devices in relatively better radio conditions. For this last use-case, the radio access node may determine the appropriate mode of operation for each individual wireless device. The wireless devices are then collected into two or more different sets, depending on their mode of operation. The different sets of wireless devices (e.g., wireless devices operating in adaptive or non-adaptive mode) are then scheduled in a time division multiplexing manner with dynamic switching.

In the following sections, the main points of the adaptive solutions and non-adaptive solutions, respectively, are outlined.

ETSI EN 300 328 v.2.1.1 specifies that non-adaptive and adaptive solutions can be applicable to either frequency hopping systems or equipment using modulations other than frequency hopping. When operating in accordance with an adaptive solution, a node (e.g., a radio access node 14 or a wireless device 12) is said to be operating in an adaptive mode or an adaptive frequency hopping mode. One example of an adaptive solution using adaptive frequency hopping mode, that may be suitable to include as one of the options in a dynamic scheme is illustrated in Figure 2. Figure 2 shows an example of frame-based LBT with three periods in each dwell time: one period for LBT, one period for downlink (D) communication and one period for uplink (U) transmission.

The radio access node 14 (e.g., eNB) determines whether or not to transmit at the beginning of each dwell time or frame based on LBT. Assuming a frame based LBT, and in case the LBT fails, the transmission is cancelled. In case the LBT succeeds, the radio access node transmits for the duration of a maximum channel occupancy time (MCOT). The MCOT may be limited by regulations. Assuming a load-based LBT and in case the CCA fails, the LBT procedure will retry sensing until transmission has been made. The wireless device (e.g., UE) 12 attempts to detect a preamble contained in the initial downlink portion of the frame. To minimize power consumption at the wireless device 12, the wireless device 12 goes to sleep in case the preamble is not detected. Depending on its length, the preamble may generate a significant overhead in the system. For simplified wireless device procedures when it comes to Hybrid Automatic Repeat Request (HARQ) operation, the main proposals focus on limiting the number of HARQ repetitions such that the full message is contained within one transmission or MCOT, or dwell time(the time spent on a specific frequency in a frequency hopping sequence, or the time period between hops). With such a limitation on the number of HARQ repetitions, the coverage of transmissions may be limited.

An example of a non-adaptive solution is shown in Figure 3. When operating in

accordance with a non-adaptive solution, a node (e.g., a radio access node 14 or a wireless device 12) is said to be operating in a non-adaptive mode or non-adaptive frequency hopping mode.

The main idea of the non-adaptive solution is to create a deterministic HARQ repetition pattern which can be used to accumulate over longer periods of time at the wireless device side. The wireless device 12 is scheduled using Physical Downlink Control Channel (PDCCH) using repetitions that may span over multiple dwell times. The wireless device 12 is configured with a Discontinuous Reception (DRX) pattern with a potentially long sleep time, and at wake-up it is required to attempt the decoding of a number of hypothetical PDCCH formats, including different repetition levels. When compared to the adaptive solution using LBT, no preamble is required as there is no uncertainty related to the LBT; consequently, the wireless device 12 will not attempt the detection of any preamble.

A number of embodiments are described herein. It should be appreciated that these embodiments may be used in combination.

In the first embodiment, a system that can mix the adaptive and non-adaptive modes using the following radio access node (e.g., eNB) and wireless device (e.g., UE) procedures and signaling is considered.

The radio access node 14 can operate in either non-adaptive or adaptive mode. In case the radio access node 14 is in the adaptive mode, it employs channel sensing or CCA. One example of an adaptive design could use a frame-based LBT as shown in relation to Figure 2, which is an example frame structure that complies with regulatory rules for adaptive frequency hopping equipment. Other frame-structures could be envisioned that would comply with regulatory rules for adaptive equipment using other modulations than frequency hopping. In case the radio access node 14 is in the non-adaptive mode, it employs a different frame structure that complies with regulatory rules for non-adaptive equipment, such as, e.g., the structure shown in relation to Figure 3. Figure 3 embodies an example of a frame structure that complies with the regulatory rules for non-adaptive frequency hopping equipment. Other frame-structures could be envisioned that would comply with regulatory rules for non-adaptive equipment using other modulations than frequency hopping.

In some embodiments, the Primary Synchronization Signal (PSS) / Secondary

Synchronization Signal (SSS) and the Master Information Block (MIB) are identical in design and position in time and frequency, regardless of the adaptivity mode configured. The PSS/SSS and MIB / System Information Block (SIB) transmission is subject to LBT whenever the radio access node 14 is operating in adaptive mode.

Wireless devices 12 will synchronize using the PSS/SSS and read the MIB. The MIB will contain an indication of the adaptivity mode. The wireless device 12 will then adopt different behavior depending on the adaptivity mode indication.

For the case of the wireless device 12 being configured in adaptive mode, the wireless device 12 will monitor the beginning of the dwell time and try and detect the preamble that indicates a successful LBT. Assuming a frame based LBT and in case no preamble is detected at the beginning of the dwell time, the wireless device 12 will go to sleep until the beginning of the next frame. Assuming an LBT for which transmissions could start at any point in time such as e.g. a load-based LBT, the device would not go to sleep, but would continue to attempt detection of preambles.

For the case of the wireless device 12 being configured in non-adaptive mode, the wireless device 12 will monitor for the PDCCH using a finite set of hypotheses of repetition level and format according to prior art procedures not considered core of the present disclosure. The radio access node 14 may change modes. The mode change will then be reflected in an updated MIB.

Note that, in an alternative embodiment, the design and/or the position in time and/or frequency of the PSS/SSS may be different for the different adaptivity modes. The radio access node 14 may then utilize the PSS/SSS to provide an implicit indication of the desired adaptivity mode. This implicit signaling may be used in addition to or as an alternative to the broadcast signaling described herein. At the wireless device 12, the wireless device 12 detects the transmitted PSS/SSS and is able to determine the desired adaptivity mode based on the design and/or position in time and/or frequency of the PSS/SSS.

Flow charts for the radio access node 14 and wireless device 12 behavior are shown in Figures 4 and 5, respectively. For all flow charts and block diagrams, optional steps or components are illustrated by dashed lines.

As illustrated in Figure 4, the adaptivity mode for the radio access node 14 may be configured, e.g., by deployment (i.e., at the time of deployment) (step 100). In this manner, the adaptivity mode of the radio access node 14 is statically defined but, in some

embodiments, can be changed, e.g., by the operator of the cellular communications network 10. The radio access node 14 indicates the adaptivity mode to wireless devices 12 attached to its cell(s) through signaling in broadcast system information, e.g. through signaling in MIB/SIB (step 102). In other words, the radio access node 14 transmits an indication of the adaptivity mode in the MIB or SIB. The radio access node 14 then performs downlink transmission in accordance with the configured adaptivity mode. More specifically, if the radio access node 14 is configured for the adaptive mode (step 104, YES), the radio access node 14 transmits using an adaptive mode, such as the frame based LBT structure, as discussed above (step 106). In other words, the radio access node 14 transmits using the adaptive mode, for example using the adaptive frequency hopping mode. Conversely, if the radio access node 14 is not configured with the adaptive mode (i.e., if the radio access node 14 is configured with the non-adaptive mode) (step 104, NO), the radio access node 14 transmits using a frame structure supporting

regulations for non-adaptive transmissions, as discussed above (step 108). In other words, the radio access node 14 transmits using the non-adaptive mode, e.g. using the non- adaptive frequency hopping mode.

As illustrated in Figure 5, at the wireless device 12, the wireless device 12 synchronizes to the cell and reads the broadcast information, e.g. the MIB or SIB to thereby obtain the indication of the adaptivity mode for the cell (step 200). The wireless device 12 then operates either in the adaptive mode or the non-adaptive mode in accordance with the indication of the adaptivity mode. More specifically, if the adaptivity mode is the adaptive frequency hopping mode (step 202, YES), the wireless device 12 attempts decoding of the preamble (i.e., the preamble in the downlink part in the frame structure as illustrated in Figure 2 where the preamble is transmitted each frame in the adaptive mode (e.g. a frame based LBT) configuration and used at the wireless device side to detect that the radio access node 14 has cleared its LBT) according to the frame structure for adaptive operation, as discussed above (step 204). In other words, the wireless device 12 operates in the adaptive frequency hopping mode for downlink reception. Conversely, if the adaptive mode is not enabled (i.e., if the non-adaptive mode is enabled) (step 202, NO), the wireless device 12 attempts decoding of PDCCH according to the frame structure for non-adaptive operation (step 206) for a frame based LBT. In other words, the wireless device 12 operates in the non-adaptive frequency hopping mode for downlink reception. The wireless device 12 reads the MIB or SIB continuously and updates accordingly.

A second embodiment relates to radio access node (e.g., eNB) scheduling and builds on the first embodiment

As illustrated in Figure 6, as a wireless device 12 (e.g., UE) attaches to the cell served by the radio access node 14, the radio access node 14 classifies the wireless device 12 to be in either normal coverage, or extended coverage (step 300). Here coverage is a measure of the range over which communication is possible. Coverage can e.g. be measured as a maximum path-loss (MPL) i.e. the maximum attenuation between a transmitter and a receiver that the system can realize before the communication link quality (in terms of e.g. throughput) becomes too low to support the intended use-case. The MPL can be used with an appropriate model of path-loss per distance covered to estimate the coverage range in terms of distance in meters. As used herein, "normal coverage" is coverage, or range, of the communication link between the node and the wireless device, that can be realized with any of the modes of operation, adaptive as well as non-adaptive. Extended coverage is the coverage, or range, of the communication link, between the node and the wireless device, that can be realized with only one of the modes, for a case where one of the modes has better coverage. It is expected that the non-adaptive mode will have better coverage due to its deterministic nature (see also below in relation to Figure 7). This means that the non-adaptive mode can reach the normal and extended coverage wireless devices, while the adaptive mode cannot reach all wireless devices, only the normal coverage wireless devices. The classification of wireless device 12 as either normal coverage or extended coverage wireless device is performed through either of:

• Measuring Signal to Noise Ratio (SNR) on uplink sounding signals. For normal coverage, the SNR is at least as high as a defined minimum SNR requirement for reception of data using the mode (adaptive or non-adaptive) that has the highest minimum SNR requirement for data reception (i.e., equal to or higher than a defined SNR threshold). If the SNR meets this requirement, the wireless device 12 is classified as a normal coverage wireless device; otherwise, the wireless device 12 is classified as an extended coverage wireless device; or

· Downlink quality such as, e.g., Reference Signal Received Power (RSRP),

Reference Signal Received Quality (RSRQ), or Channel Quality Indication (CQI) reported back to the radio access node 14. For normal coverage, the quality is at least as high as a minimum downlink quality requirement for reception of data using the mode (adaptive or non-adaptive) that has the highest minimum downlink quality requirement for data reception (i.e., equal to or higher than a defined quality threshold). If the wireless device 12 meets this requirement, then the wireless device 12 is classified as a normal coverage wireless device; otherwise, the wireless device 12 is classified as an extended coverage wireless device.

Optionally, the radio access node 14 creates one set or group of wireless devices containing the wireless devices 12 classified as being normal coverage wireless devices and another set or group of wireless devices containing the wireless devices 12 classified as extended coverage wireless devices. The radio access node 14 determines whether to enable or disable adaptive mode or choose the adaptivity mode for the coming scheduling period (step 302). This

determination is based on:

• Whether extended coverage wireless devices 12 need to be scheduled:

o Whether or not extended coverage wireless devices 12 need to be scheduled can be based on any suitable scheduling algorithm taking into account, e.g.:

^■ Buffer status

^■ Current link quality

^■ Quality of Service (QoS) requirements

o Extended coverage wireless devices 12 may require the non-adaptive mode of operation due to the improved coverage associated with this mode of operation

• Statistics on channel medium utilization during times when adaptive mode (with LBT) was used. When using the adaptive mode of operation, the channel medium utilization will depend on the LBT success ratio, with no lower limit. The non-adaptive mode of operation guarantees a minimum channel medium utilization but is restricted by a limit of the maximum allowed channel medium utilization. One example of how to use the statistics of channel medium utilization when determining the adaptivity mode could therefore be to prefer to enable adaptive mode whenever the channel medium utilization in the past scheduling period(s) has been larger than the maximum channel medium utilization allowed when using the non-adaptive mode of operation.

• Interference measurements. In high interference scenarios, again non- adaptive mode may be preferred in order to secure access to the channel.

• Load and buffer status of normal coverage wireless devices 12. When the buffer status of the normal coverage wireless devices 12 is such that a higher capacity is required to serve more wireless devices 12 (implying higher load of the cell), adaptive mode may be preferred in order to increase the medium utilization above the maximum limit restricting the non-adaptive mode. Hence, selecting the adaptive mode when the load is higher than a load threshold. Once the adaptivity mode is determined, the radio access node 14 indicates the adaptivity mode to wireless devices 12, e.g., through signaling in broadcast system information, e.g. through signaling in MIB/SIB (step 304). In other words, the radio access node 14 transmits an indication of the adaptivity mode, e.g., in the MIB or SIB. Alternatively, the indication may be transmitted via dedicated signaling, as described below. The radio access node 14 then performs downlink transmission in accordance with the configured adaptivity mode. More specifically, if the radio access node 14 is configured for the adaptive mode (step 306, YES), the radio access node 14 transmits using an adaptive mode, such as a frame based LBT structure as discussed above (step 308). In other words, the radio access node 14 transmits using the adaptive mode, for example the adaptive frequency hopping mode. Conversely, if the radio access node 14 is not configured with the adaptive mode (i.e., if the radio access node 14 is configured with the non-adaptive mode) (step 306, NO), the radio access node 14 transmits using a frame structure supporting regulations for non-adaptive transmissions, as discussed above (step 310). In other words, the radio access node 14 transmits using the non-adaptive mode, for example the non-adaptive frequency hopping mode.

The wireless device 12 behavior is the same as for the first embodiment described above and in relation to Figure 5.

To further clarify the workings of the dynamic scheduling consider the following examples. In the first example as shown in Figure 7, wireless devices WD_H and WD_L are classified as normal coverage wireless devices 12 and wireless device WD_M is classified as an extended coverage wireless device 12. The disc in Figure 7 represents the border of positions of wireless devices classified as normal coverage wireless devices or extended coverage wireless devices. In case the radio access node 14, which may use a

conventional scheduling algorithm, has concluded that WD_M is to be scheduled, the radio access node 14 selects non-adaptive mode, as this mode realizes extended coverage and hence is the only mode that can be used to reach WD_M. Depending on the amount of data to be served to WD_M and the length of the scheduling period chosen, there may be room to also serve WDH and/or WDL during this time period. This is possible to do since WDH and WD_L are reachable with any of the adaptivity modes.

In a following scheduling period, it may happen that only normal coverage wireless devices 12 are to be scheduled (i.e., WDH and/or WDL in this example). This time the radio access node 14 can choose the adaptivity mode based on what mode it expects to give the best medium utilization. In the example of Figure 7, there is low interference from other systems, and hence the LBT associated with adaptive mode will clear or be successful with a high probability. The radio access node 14 now uses statistics of previous scheduling periods where adaptive mode was chosen to calculate the rate of LBT success. It determines the historic LBT success rate to be high, and it calculates the medium utilization in terms of percentage of time it was able to access the channel. The radio access node 14 further computes interference measurements performed during idle times. It may also use the buffer status to see if there is a need to access the channel with a high rate. In the example let's assume there is a lot of data in the wireless device buffers, and that the radio access node 14 would like to maximize the channel access rate. Assume further that the historic channel medium utilization was 40% and that the maximum allowed channel medium utilization when operating in non-adaptive mode is 10%. Assume further that the radio access node 14 measures the interference level and deems it to be low, i.e. below an interference threshold. The radio access node 14 may now form a decision metric based on weighting and adding any or all of these measurements and compare this to a threshold for enabling of adaptive mode. The radio access node 14 thus selects adaptive mode for the coming scheduling period.

In a second example, using the same scenario, but here with added high interference from other systems, e.g. WiFi stations (STAs). The scenario is depicted in Figure 8. The disc in Figure 8 represents the border of positions of wireless devices classified as normal coverage wireless devices or extended coverage wireless devices. For the case when WDM is to be scheduled, just as in the first scenario, the only option to choose for the radio access node 14 is the non-adaptive mode. However, as we turn to the case when only normal wireless devices 12 are to be scheduled, the radio access node 14 now measures historic LBT success rate to be low, and determines the historic medium utilization to be, e.g., 5%, which is lower than the guaranteed medium utilization associated with the non- adaptive mode. The radio access node 14 also measures the interference to be high, i.e. above an interference threshold. Finally, the radio access node 14 forms the same decision metric as in the first example but selects non-adaptive mode for the coming scheduling period. A third embodiment builds on the first embodiment, but where dedicated signaling rather than broadcast signaling is used to indicate the adaptivity mode for each wireless device 12. The radio access node 14 (e.g., eNB) may then switch adaptivity mode back and forth, e.g., so as to serve the wireless devices 12 that have a matching adaptivity state at each point in time. The dedicated signaling to indicate whether adaptive mode is enabled could be done through semi-static Radio Resource Control (RRC) signaling or as part of PDCCH signaling.

The wireless device 12 receives the dedicated signaling and adapts its behavior

accordingly as described in the first embodiment, and also briefly described below.

In some embodiments, a wireless device 12 is by default configured in non-adaptive mode and attempts to decode the PDCCH using a finite set of hypotheses of repetition level and format, e.g., according to conventional procedures.

In case the wireless device 12 receives dedicated signaling indicating adaptivity mode, the wireless device 12 follows the indication from this dedicated signaling.

For the case of the wireless device 12 being configured in adaptive mode, the wireless device 12 will monitor the beginning of the dwell time and try and detect the preamble that indicates a successful LBT. Assuming a frame-based LBT and in case no preamble is detected at the beginning of the dwell time, the wireless device 12 will go to sleep until the beginning of the next frame. Assuming an LBT for which transmissions could start at any point in time such as e.g. a load-based LBT, the device would not go to sleep, but would continue to attempt detection of preambles.

A fourth embodiment builds on the first and third embodiments, but here both broadcast and dedicated signaling is used to indicate the adaptivity mode for each wireless device 12. The radio access node 14 may, e.g., first signal a default adaptivity mode via broadcast signaling and thereafter signal an adaptivity mode to particular wireless devices 12 via dedicated signaling. The dedicated signaling to indicate whether adaptive mode is enabled could be done through semi-static Radio Resource Control (RRC) signaling or as part of PDCCH signaling (e.g. PDCCH or dedicated RRC signaling). At the wireless device 12, the wireless device 12 listens for both the broadcast and dedicated signaling and operates in accordance with the most recently received signaling. Flow charts showing the radio access node 14 (e.g., eNB) and the wireless device 12 (e.g., UE) behaviors with respect to the third or fourth embodiments, are shown in Figures 9 and 10, respectively.

As illustrated in Figure 9, as a wireless device 12 (e.g., UE) attaches to the cell, the radio access node 14 classifies the wireless device 12 to be in either normal coverage, or extended coverage, as described above with respect to step 300 of Figure 6 (step 400). The radio access node 14 determines the adaptivity mode for the upcoming scheduling interval (i.e., determines whether to enable or disable adaptive mode for the upcoming scheduling interval), as described above with respect to step 302 of Figure 6 (step 402). In this embodiment, a default adaptivity mode is the non-adaptive mode. The default adaptivity mode may be predefined (e.g., by standard) or preconfigured (e.g., by broadcast signaling such as, e.g., MIB or SIB). Thus, in step 402, the radio access node 14 also determines whether any of the wireless devices 12 require a change in adaptivity mode. More specifically, the default adaptivity mode may be the non-adaptive mode. Consider an example where in step 402 the radio access node 14 selects the adaptive mode, e.g., because a relatively large number of normal coverage wireless devices 12 need to be scheduled in the upcoming scheduling interval. Further consider a scenario in which not all of the wireless devices 12 are capable of operating in the adaptive mode or a scenario in which some of the wireless devices 12 are extended coverage wireless devices for which non-adaptive mode is desired. In this example, the radio access node 14 then determines that only some of the wireless devices 12 should be changed to the adaptive mode.

The radio access node 14 indicates the adaptivity mode to the wireless devices 12 needing a change using dedicated signaling (step 404). In some embodiments the adaptivity mode signaled by dedicated signaling is an updated adaptivity mode that essentially overrides the adaptivity mode signaled by the MIB or SIB. In other embodiments, the indication transmitted via dedicated signaling in step 404 is an initial adaptivity mode indication for the respective wireless device(s) 12.

The radio access node 14 determines whether normal or extended coverage wireless devices 12 should be scheduled for the upcoming scheduling interval (e.g., a burst or Transmit Time Interval (TTI)) (step 406). This determination corresponds to the

determining of the adaptivity mode in step 402. For instance, if the radio access node 14 determines to use the non-adaptive mode in step 402, then the radio access node 14 determines that at least extended coverage wireless devices 12 and potentially normal coverage wireless devices 12 are to be scheduled in the upcoming scheduling interval. Conversely, if the radio access node 14 determines to use the adaptive mode in step 402, then the radio access node 14 determines that, e.g., normal coverage wireless devices 12 are to be scheduled in the upcoming scheduling interval.

The radio access node 14 then performs downlink transmission in accordance with the configured adaptivity mode. More specifically, if the radio access node 14 is configured for the adaptive mode (step 408, YES), the radio access node 14 transmits using an adaptive mode, e.g. a frame based LBT structure, as discussed above (step 410). In other words, the radio access node 14 transmits using the adaptive mode, for example the adaptive frequency hopping mode. Conversely, if the radio access node 14 is not configured with the adaptive mode (i.e., if the radio access node 14 is configured with the non-adaptive mode) (step 408, NO), the radio access node 14 transmits using a frame structure supporting regulations for non-adaptive transmissions, as discussed above (step 412). In other words, the radio access node 14 transmits using the non-adaptive mode, for example the non-adaptive frequency hopping mode. This process may then be repeated for the next scheduling interval.

As illustrated in Figure 10, at the wireless device 12, the wireless device 12 synchronizes to the cell and reads the MIB and SIB (step 500). In this example, the MIB or SIB includes an indication of an adaptivity mode, as described above. The wireless device 12 sets its adaptivity mode as indicated in the latest received MIB or SIB (step 502). For this example, the frame based LBT is described, but similar application could be made with the load- based LBT.

The wireless device 12 then operates either in the adaptive mode or the non-adaptive mode in accordance with its set adaptivity mode. More specifically, if the set adaptivity mode is the adaptive mode (step 504, YES), the wireless device 12 attempts decoding of the preamble according to the frame structure for adaptive operation, as discussed above (step 506). In other words, the wireless device 12 operates in the adaptive mode for downlink reception, such as in the adaptive frequency hopping mode. Conversely, if the set adaptive mode is not enabled (i.e., if the non-adaptive mode is enabled) (step 504,

NO), the wireless device 12 attempts decoding of PDCCH according the frame structure for non-adaptive operation (step 508). In other words, the wireless device 12 operates in the non-adaptive mode for downlink reception, such as in the non-adaptive frequency hopping mode.

The wireless device 12 determines whether an indication of an adaptivity mode for the wireless device 12 is received via broadcast signaling (e.g., MIB or SIB) or dedicated signaling (step 510). If not, the process returns to step 504 and is repeated. If an indication of adaptivity mode is received by the wireless device 12 via broadcast or dedicated signaling, the wireless device 12 sets its adaptivity mode according to the received indication (step 512). The process then returns to step 504 and is repeated. Figure 1 1 is a schematic block diagram of the wireless device 12 (e.g., UE) according to some embodiments of the present disclosure. As illustrated, the wireless device 12 includes circuitry 20 comprising one or more processors 22 (e.g., Central Processing Units (CPUs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), Digital Signal Processors (DSPs), and/or the like) and memory 24. The wireless device 12 also includes one or more transceivers 26 each including one or more transmitters 28 and one or more receivers 30 coupled to one or more antennas 32. In some embodiments, the functionality of the wireless device 12 described above may be implemented in hardware (e.g., via hardware within the circuitry 20 and/or within the processor(s) 22) or be implemented in a combination of hardware and software (e.g., fully or partially implemented in software that is, e.g., stored in the memory 24 and executed by the processor(s) 22).

In some embodiments, a computer program including instructions which, when executed by the at least one processor 22, causes the at least one processor 22 to carry out at least some of the functionality of the wireless device 12 according to any of the embodiments described herein is provided. In some embodiments, a carrier containing the

aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as memory).

Figure 12 is a schematic block diagram of the wireless device 12 (e.g., UE) according to some other embodiments of the present disclosure. The wireless device 12 includes one or more modules 34, each of which is implemented in software. The module(s) 34 provide the functionality of the wireless device 12 described herein. For example, the modules(s) 34 may include modules operable to perform the functions of steps 200 through 206 of Figure 5 and/or steps 500 through 512 of Figure 10.

Figure 13 is a schematic block diagram of a network node 36 (e.g., a radio access node 14 such as, for example, an eNB) or a core network node according to some embodiments of the present disclosure. As illustrated, the network node 36 includes a control system 38 that includes circuitry comprising one or more processors 40 (e.g., CPUs, ASICs, DSPs, FPGAs, and/or the like) and memory 42. The control system 38 also includes a network interface 44. In embodiments in which the network node 36 is a radio access node 14, the network node 36 also includes one or more radio units 46 that each include one or more transmitters 48 and one or more receivers 50 coupled to one or more antennas 52. In some embodiments, the functionality of the network node 36 (e.g., the functionality of the radio access node 14 or eNB) described above may be fully or partially implemented in software that is, e.g., stored in the memory 42 and executed by the processor(s) 40. Figure 14 is a schematic block diagram that illustrates a virtualized embodiment of the network node 36 (e.g., the radio access node 14 or a core network node) according to some embodiments of the present disclosure. As used herein, a "virtualized" network node 36 is a network node 36 in which at least a portion of the functionality of the network node 36 is implemented as a virtual component (e.g., via a virtual machine(s) executing on a physical processing node(s) in a network(s)). As illustrated, the network node 36 optionally includes the control system 38, as described with respect to Figure 13. In addition, if the network node 36 is the radio access node 14, the network node 36 also includes the one or more radio units 46, as described with respect to Figure 13. The control system 38 (if present) is connected to one or more processing nodes 54 coupled to or included as part of a network(s) 56 via the network interface 44. Alternatively, if the control system 38 is not present, the one or more radio units 46 (if present) are connected to the one or more processing nodes 54 via a network interface(s). Alternatively, all of the functionality of the network node 36 described herein may be implemented in the processing nodes 54. Each processing node 54 includes one or more processors 58 (e.g., CPUs, ASICs, DSPs, FPGAs, and/or the like), memory 60, and a network interface 62.

In this example, functions 64 of the network node 36 (e.g., the functions of the radio access node 14 or eNB) described herein are implemented at the one or more processing nodes 54 or distributed across the control system 38 (if present) and the one or more processing nodes 54 in any desired manner. In some particular embodiments, some or all of the functions 64 of the network node 36 described herein are implemented as virtual components executed by one or more virtual machines implemented in a virtual

environment(s) hosted by the processing node(s) 54. As will be appreciated by one of ordinary skill in the art, additional signaling or communication between the processing node(s) 54 and the control system 38 (if present) or alternatively the radio unit(s) 46 (if present) is used in order to carry out at least some of the desired functions. Notably, in some embodiments, the control system 38 may not be included, in which case the radio unit(s) 46 (if present) communicates directly with the processing node(s) 54 via an appropriate network interface(s).

In some particular embodiments, higher layer functionality (e.g., layer 3 and up and possibly some of layer 2 of the protocol stack) of the network node 36 may be implemented at the processing node(s) 54 as virtual components (i.e., implemented "in the cloud") whereas lower layer functionality (e.g., layer 1 and possibly some of layer 2 of the protocol stack) may be implemented in the radio unit(s) 46 and possibly the control system 38. The network node 14, 36 is adapted to determine a select adaptivity mode for downlink transmissions, the select adaptivity mode being one of a predefined set of adaptivity modes comprising an adaptive mode and a non-adaptive mode. It is further adapted to indicate the select adaptivity mode to one or more wireless devices 12 and perform downlink transmissions using the select adaptivity mode.

The adaptive mode may be an adaptive frequency hopping mode and the non-adaptive mode may be a non-adaptive frequency hopping mode.

In some embodiments, a computer program including instructions which, when executed by the at least one processor 40, 58, causes the at least one processor 40, 58 to carry out the functionality of the network node 36 or a processing node 54 according to any of the embodiments described herein is provided. In some embodiments, a carrier containing the aforementioned computer program product is provided. The carrier is one of an electronic signal, an optical signal, a radio signal, or a computer readable storage medium (e.g., a non-transitory computer readable medium such as the memory 60).

Figure 15 is a schematic block diagram of the network node 36 (e.g., the radio access node 14 or a core network node) according to some other embodiments of the present disclosure. The network node 36 includes one or more modules 66, each of which is implemented in software. The module(s) 66 provide the functionality of the network node 36 described herein. In some embodiments, the module(s) 66 may comprise, for example, modules operable to perform the functions of steps 100 through 108 of Figure 4, the functions of steps 300 through 310 of Figure 6, and/or the functions of steps 400 through 412 of Figure 9. A network node 14, 36 for a cellular communications network 10, comprises a determining module 66 operable to determine a select adaptivity mode for downlink transmissions. The select adaptivity mode being one of a predefined set of adaptivity modes comprising an adaptive mode and a non-adaptive mode. The network node further comprises an indicating module 66 being operable to indicate the select adaptivity mode to one or more wireless devices 12 and a performing module 66 being operable to perform downlink transmissions using the select adaptivity mode.

Those skilled in the art will recognize improvements and modifications to the embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein.

Claims

1. A method of operation of a network node (14, 36), comprising:

determining (302, 402), based on the type of wireless devices (12) that need to be scheduled during the upcoming scheduling interval, a select adaptivity mode for downlink transmissions during the upcoming scheduling interval, the select adaptivity mode being one of a predefined set of adaptivity modes comprising an adaptive mode and a non- adaptive mode;

indicating (304, 404) the select adaptivity mode to one or more wireless devices (12); and

performing (308-310; 410-412) downlink transmissions using the select adaptivity mode.

2. The method of claim 1 further comprising classifying (300; 400) the type of wireless devices that need to be scheduled during the upcoming scheduling interval as normal coverage wireless devices or extended coverage wireless devices.

3. The method of claim 2, wherein the classifying the type of wireless devices that need to be scheduled during the upcoming scheduling interval as normal coverage wireless devices or extended coverage wireless devices is based on measuring signal to noise ratio on uplink sounding signals or measuring downlink quality.

4. The method of claim 2 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval based on whether normal coverage wireless devices (12) or extended coverage wireless devices (12) need to be scheduled during the upcoming scheduling interval.

5. The method of any of claim 1 -4 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval based on a number of extended coverage wireless devices (12) needed to be scheduled during the upcoming scheduling interval.

6. The method of any one of claims 1 -5 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval based on one or more channel characteristics of a corresponding downlink channel.

7. The method of any one of claims 1 -6 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval based on one or more statistics regarding utilization of a corresponding downlink channel.

8. The method of any one of claims 1 -7 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises:

selecting the adaptive mode as the select adaptive mode if utilization of a corresponding downlink channel in one or more past scheduling intervals exceeds a maximum utilization allowed when using the non-adaptive mode.

9. The method of any one of claims 1 -8 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises:

selecting the non-adaptive mode as the select adaptivity mode if utilization of the corresponding downlink channel in the one or more past scheduling intervals does not exceed a predefined, predetermined, or preconfigured threshold.

10. The method of any one of claims 1 -9 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval further comprises: selecting the adaptive mode as the select adaptivity mode if utilization of the corresponding downlink channel in the one or more past scheduling intervals exceeds a predefined, predetermined, or preconfigured threshold.

1 1 . The method of any one of claims 1 -10 wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval based on load and buffer status of normal coverage wireless devices (12).

12. The method of any one of claims 1 -1 1 wherein, determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises:

selecting the non-adaptive mode as the select adaptivity mode if interference is above an interference threshold.

13. The method of any one of claims 1 -1 1 wherein, determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises:

selecting the adaptive mode as the select adaptivity mode if interference is below an interference threshold.

14. The method of claim 1-13 wherein, determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises: selecting the adaptive mode as the select adaptivity mode if a load is higher than a load threshold.

15. The method of any one of claims 1 -14 wherein indicating (304, 404) the select adaptivity mode to the one or more wireless devices (12) comprises indicating (304) the select adaptivity mode in broadcasted system information; and/or indicating (404) the selecting frequency hopping adaptivity mode in dedicated signaling.

16. The method of any one of claims 4-15, wherein determining (302, 402) the select adaptivity mode for downlink transmissions during the upcoming scheduling interval comprises:

selecting the non-adaptive mode as the select adaptivity mode if extended coverage wireless devices need to be scheduled.

17. The method of any one of claims 1 -16 wherein the adaptive mode is an adaptive frequency hopping mode and the non-adaptive mode is a non-adaptive frequency hopping mode.

18. A network node (14, 36) for a cellular communications network (10), the network node 14, 36) adapted to:

determine, based on the type of wireless devices (12) that need to be scheduled during an upcoming scheduling interval, a select adaptivity mode for downlink

transmissions during the upcoming scheduling interval, the select adaptivity mode being one of a predefined set of frequency hopping adaptivity modes comprising an adaptive mode and a non-adaptive mode;

indicate the select frequency hopping adaptivity mode to one or more wireless devices (12); and

perform downlink transmissions using the select frequency hopping adaptivity mode.

19. The network node (14, 36) of claim 18 wherein the network node (14, 36) is further adapted to perform the method of any one of claims 2-17.