Scheduling wireless communications based on aging metrics

Abstract

Aspects of the present application relate to scheduling wireless communications based on channel estimation aging. A channel estimate may be generated based on a signal wirelessly transmitted by a user equipment. An aging metric associated with the channel estimate may be determined. Wireless communications with at least some of the user equipments may be scheduled based on the aging metrics.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to wireless communications, and more particularly to scheduling and / or rate selection for wireless communications.

[0002] Cross-reference to priority application

[0003] This application claims priority to U.S. Provisional Patent Application No. 63 / 365,113, filed on May 20, 2022, entitled “Scheduling Wireless Communications Based on Aging Metrics,” and claims priority to U.S. Provisional Patent Application No. 63 / 365,111, filed on May 20, 2022, entitled “Wireless Communications Rate Selection Based on Aging Metrics,” the disclosures of each of which are hereby incorporated by reference in their entirety and for all purposes. Background Art

[0004] In a wireless communication system, there may be multiple user equipments (UEs) arranged to communicate wirelessly with a communication network. Channel estimates may be generated from reference signals (such as sounding reference signals). Channel estimates may be used to mitigate intra-cell interference. High data rates and / or low latency communications are typically required. Where high data rates are required, there may be dense UE deployments. There may be technical challenges in efficiently utilizing wireless communication resources while maintaining relatively low intra-cell interference. Summary of the invention

[0005] The innovations described in the claims each have multiple aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the claims, some of the prominent features of the application will now be briefly described.

[0006] One aspect of the present application is a method for scheduling wireless communications based on channel estimate aging. The method includes generating a channel estimate based on a signal wirelessly transmitted by a user device, determining an aging metric associated with the channel estimate, and scheduling wireless communications with at least some of the user devices based on the aging metric.

[0007] The signal wirelessly transmitted by the user equipment may be a sounding reference signal. A first sounding reference signal among the sounding reference signals may be wirelessly transmitted by a first user equipment among the user equipment in a first time slot. A second sounding reference signal among the sounding reference signals may be wirelessly transmitted by a second user equipment among the user equipment in a second time slot, wherein the second time slot follows the first time slot.

[0008] The wireless communication may be a time division duplex (TDD) multiple input multiple output (MIMO) wireless communication.

[0009] One of the aging metrics may be based only on a time delay associated with a respective channel estimate. One of the aging metrics may be based on a mobility of a channel associated with a respective channel estimate and a time delay associated with the respective channel estimate. One of the aging metrics may be based on a channel quality prediction associated with a respective channel estimate and a time delay associated with the respective channel estimate.

[0010] The scheduling may include selecting a first set of antenna ports of the user equipment for wireless communication during a time slot based on a corresponding first aging metric of the aging metrics indicating lower channel uncertainty, and not scheduling a second set of antenna ports of the user equipment for wireless communication during the time slot based on a corresponding second aging metric of the aging metrics indicating high channel uncertainty. The scheduling may include using at least some of the aging metrics to determine a user equipment priority for a time slot. The scheduling may include reducing a number of layers of the wireless communication used for a time slot. The scheduling may include reducing a number of layers of the wireless communication used for a time slot.

[0011] The scheduling may include using at least some of the aging metrics to determine a user equipment priority for a time slot. The determining of the user equipment priority for a time slot may also be based on one or more quality of service metrics. The scheduling may include reducing a number of layers of wireless transmission for a time slot.

[0012] The scheduling may include reducing the number of layers used for wireless communication for a time slot.

[0013] The method may further include performing modulation and coding scheme selection for a set of antenna ports of the user equipment scheduled for a time slot based on at least some of the aging metrics.

[0014] Another aspect of the present application is a non-transitory computer-readable storage comprising computer-executable instructions, wherein when executed by a baseband unit, the computer-executable instructions cause any of the methods disclosed herein to be performed.

[0015] Another aspect of the present application is a system for wireless communication. The system includes a baseband unit including at least one processor and storing instructions, which when executed by the at least one processor, cause the baseband unit to perform operations. The operations include generating a channel estimate based on a signal received from a user device, determining an aging metric associated with the channel estimate, and scheduling wireless communications with at least some of the user devices based on the aging metric.

[0016] The system may include one or more radio units in communication with the baseband unit. The one or more radio units may be configured to wirelessly communicate with at least some of the user devices via the wireless communication. The one or more radio units may include distributed remote radio units.

[0017] Another aspect of the present application is a method for scheduling wireless communications. The method includes receiving sounding reference signals from user devices in different uplink time slots, generating channel estimates based on the sounding reference signals received in the different uplink time slots, and scheduling wireless communications with at least some of the user devices based on the time at which the sounding reference signals were received from at least some of the user devices.

[0018] Another aspect of the present application is a method for user equipment rate selection based on channel estimate aging. The method includes generating a channel estimate based on a signal wirelessly transmitted by a user equipment, determining an aging metric associated with the channel estimate, and performing modulation and coding scheme selection for a group of the user equipment based on at least some of the aging metrics.

[0019] Another aspect of the present application is a wireless communication system. The system includes a baseband unit, which includes at least one processor and stores instructions, wherein when executed by the at least one processor, the instructions cause the baseband unit to perform operations. The operations include generating channel estimates based on signals received from user devices, determining an aging metric associated with the channel estimates, and selecting a modulation and coding scheme for a group of user devices based on at least some of the gain metrics. The system may include one or more radio units in communication with the baseband unit, wherein the one or more radio units are configured to wirelessly communicate with the group of user devices using the selected modulation and coding scheme. The one or more radio units may include distributed remote radio units.

[0020] Another aspect of the present application is a computer readable memory comprising instructions that, when executed by one or more processors, cause any of the methods disclosed herein to be performed.

[0021] For the purpose of summarizing the present application, certain aspects, advantages and novel features of the innovations are described herein. It should be understood that not all of these advantages can be implemented according to any particular embodiment. Therefore, these innovations can be embodied or performed in a manner that realizes or optimizes one advantage or group of advantages taught herein, without having to realize other advantages taught or suggested herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the present application will now be described by way of non-limiting examples with reference to the accompanying drawings.

[0023] Figure 1A A user equipment (UE) is illustrated having antenna ports divided into groups. Figure 1B The mapping of antenna port groups to time slots for two UEs is illustrated.

[0024] Figure 2 is a flow chart of a method of scheduling wireless communications according to an embodiment.

[0025] Figure 3 is a diagram illustrating a mapping of transmit groups to time slots for time division duplex (TDD) wireless communications with UE antenna port scheduling having up-to-date sounding reference signal (SRS) channel estimates according to an embodiment.

[0026] Figure 4A is a timing diagram illustrating an example frame structure and processing delays associated with channel estimation. Figure 4B is a graph illustrating example channel annual aging priorities over time.

[0027] Figure 5A is a timing diagram illustrating an example frame structure and processing delays associated with channel estimation. Figure 5B is an example graph illustrating a reduction in the number of wireless communication layers over time due to channel estimation aging.

[0028] Figure 6 is a flow chart of a rate selection method according to an embodiment.

[0029] Figure 7 is a flow chart of a method of scheduling wireless communications according to an embodiment.

[0030] Figure 8 is a timing diagram illustrating handling of retransmissions in SRS-aware scheduling according to an embodiment.

[0031] Fig. 9 is a timing diagram illustrating prioritization of UEs with guaranteed bit rate (GBR) quality of service (QoS) specification and SRS-aware scheduling according to an embodiment.

[0032] Fig.10 is a timing diagram illustrating an example frame structure and staggered SRS transmission according to an embodiment.

[0033] Fig.11 An example of a multiple transmit / receive point network is illustrated.

[0034] Fig.12 is a block diagram of an example network system with scheduling and / or rate selection based on channel estimate aging, according to an embodiment.

[0035] Fig.13is a diagram illustrating an example multiple-input multiple-output (MIMO) network environment in which scheduling and / or rate selection based on channel estimate aging may be implemented. DETAILED DESCRIPTION

[0036] The following description of certain embodiments gives various descriptions of specific embodiments. However, the innovations described herein may be embodied in a variety of different ways, such as defined and covered by the claims. In this specification, reference is made to the accompanying drawings in which similar reference numerals may indicate identical or functionally similar elements. It should be understood that the elements shown in the accompanying drawings are not necessarily drawn to scale. In addition, it should be understood that certain embodiments may include more elements than a subset of the elements shown in and / or illustrated in the accompanying drawings. In addition, some embodiments may combine any suitable combination of features from two or more of the accompanying drawings.

[0037] The wireless communication system may have specifications for various communication parameters. For example, the wireless communication system may have specifications for high data rate applications, such as extended reality and / or enhanced mobile broadband applications. As another example, the wireless communication system may have specifications for ultra-reliable and low latency applications. The wireless communication system may have specifications for other verticals, including automotive and extensions of high data rate and / or ultra-reliable and low latency, such as metaverse applications.

[0038] In practice, high data rate use cases can occur in dense small cell deployment scenarios. In this case, user equipment (UE) can be densely located in a specific geographical location. In this case, multi-user multiple input multiple output (MU-MIMO) applications can provide relatively high spectral efficiency for a given bandwidth. Time division duplex (TDD) multiple input multiple output (MIMO) systems can support downlink MU-MIMO based on sounding reference signal (SRS) by exploiting channel reciprocity. Channel state information (CSI) at the base station can be used to construct the downlink precoder to mitigate and / or eliminate intra-cell interference between data streams transmitted on the same time-frequency resources.

[0039] Although channel estimates based on SRS received from UEs can be used to mitigate intra-cell interference, channel estimates may age. As more time passes from when the channel estimates were generated, the uncertainty associated with the channel estimates increases. Channel estimate aging can reduce the intra-cell orthogonality provided by the precoder because channel conditions can change due to the transmission of the SRS from the UE. For example, due to mobility, the channel may evolve relative to when the SRS was transmitted from the UE. As channel conditions change, the precoder may become outdated. Channel estimate aging may alternatively or additionally be affected by processing and / or scheduling delays at the base station.

[0040] Another technical challenge is SRS capacity. SRS resources are limited. This can limit the number of UEs and antenna ports per UE that can be used for downlink beamforming. During a specific time slot, only some UEs can transmit SRS in certain applications. Using aged channel estimates can lead to aging effects and increased interference. For periodic SRS transmissions, there is a trade-off between increasing the SRS period to support more UEs and the performance loss due to channel aging.

[0041] It is desirable to utilize SRS resources efficiently. By dividing UEs and their corresponding SRS antenna ports into different disjoint transmission groups (virtual UEs), SRS resource utilization can be enhanced. Figure 1A A UE is illustrated with antenna ports divided into groups. Figure 1B The mapping of antenna port groups to time slots for two UEs is illustrated.

[0042] Figure 1A UE 10 is shown, whose SRS antenna ports P0, P1, P2 and P3 are divided into two different transmission groups. The first transmission group includes SRS antenna ports P0 and P1 and corresponds to virtual UE0; the second transmission group includes SRS antenna ports P2 and P3 and corresponds to virtual UE1.

[0043] In some applications, such as Figure 1B , each transmit group in the wireless communication system may include a configured SRS antenna port subset for a UE subset. Some or all of the transmit groups may include all antenna ports for one or more UEs of a UE subset in various applications. In some applications, some or all of the transmit groups may include antenna port subsets for one or more UEs. Different transmit groups may transmit in different time slots.

[0044] Figure 1B 1 shows a mapping of transmit groups to time slots for TDD wireless communication. In a first time slot, transmit group 0 may transmit. Transmit group 0 includes SRS antenna ports P0 and P1 of a first UE 10A. In a second time slot, transmit group 1 may transmit. Transmit group 1 includes SRS antenna ports P0 and P1 of a second UE 10B. In a third time slot, the first UE 10A may transmit from SRS antenna ports P2 and P3. In a fourth time slot, the second UE 10B may transmit from SRS antenna ports P2 and P3. Figure 1B As shown, the first UE 10A can divide the SRS antenna ports into different transmission groups. The SRS can be transmitted from these antenna ports at different times associated with the transmission. The aging of the SRS channel estimate may cause technical problems. Even with efficient SRS resource utilization, there are still technical challenges associated with channel estimation aging.

[0045] Various aspects of the present application relate to scheduling wireless communications based on the aging of SRS channel estimates. Such scheduling can mitigate the effects of channel estimate aging. UE selection can give priority to UEs with recently transmitted SRS. Rate selection and / or layer selection of the selected UE can be based on an aging metric. The aging metric is based on the aging of the SRS channel estimate. In some cases, the aging metric is also based on one or more additional parameters, such as mobility and / or channel estimate quality measurements. Considering the aging of the SRS channel estimate when scheduling wireless communications can be referred to as SRS-aware scheduling.

[0046] Methods for scheduling wireless communications based on the aging of SRS estimates are disclosed. A first method involves scheduling only UEs that have recently transmitted SRS. A second method includes using SRS channel estimate aging in UE priority calculations, which are used to select UEs to be scheduled. Of all eligible UEs in each time slot, the UE with the highest UE priority can be scheduled for transmission in that time slot. A third method includes scheduling fewer layers with increased channel estimate aging to mitigate the effects of aging. Any suitable principles and advantages of these methods can be implemented together with each other. For any of these scheduling methods, modulation and coding scheme (MCS) selection can also be performed based on the aging metric of the scheduled UE. The scheduling wireless communication method disclosed herein can be performed by any suitable circuit and / or hardware, such as a baseband unit (BBU) of a base station specifically configured to perform the operations of the method. Such a BBU may include at least one processor and store instructions that, when executed by at least one processor, result in the execution of some or all of the operations of the method disclosed herein. In some cases, the BBU includes a centralized unit (CU) and at least one distributed unit (DU). Reference will be made to Figures 2 to 5B Example methods for scheduling wireless communications based on aging of SRS channel estimates are discussed.

[0047] Figure 2 2 is a flow chart of a method 20 for scheduling wireless communication according to an embodiment. The UE may wirelessly transmit an SRS to a network system. The network system may receive the SRS. In block 22, the network system may generate a channel estimate based on the SRS received from the UE. The BBU may generate a channel estimate.

[0048] At block 24, an aging metric may be determined for the channel estimate. The aging metric is based on the aging of the corresponding channel estimate. The aging metric may be based purely or solely on a time delay associated with the channel estimate. The time delay may indicate how long ago the channel was sampled. The time delay may indicate a delay between SRS transmission and / or reception and scheduling. For example, the aging metric may be or represent a timestamp associated with the channel estimate, an amount of time since the channel estimate was generated, or an amount of time since the SRS was received. The aging metric may be based on a time delay associated with the channel estimate and one or more other parameters.

[0049] In some applications, the aging metric may also be based on the Doppler of the channel. In such applications, determining the aging metric at block 24 may include estimating the Doppler of the channel. Such an aging metric is based on the time delay and the mobility of the channel. A high aging metric value indicating high channel aging may be the result of a low time delay and high channel mobility. A high aging metric value indicating high channel aging may be the result of a high time delay and low channel mobility.

[0050] In some applications, the aging metric may be based on a measurement of time delay and channel prediction quality. In such applications, determining the aging metric at block 24 may include estimating the prediction quality of the channel. A high aging metric value indicating high channel aging may be the result of a high prediction error. A low aging metric value indicating low channel aging may be the result of a low prediction error. Even in the case of high mobility, a low aging metric value indicating low channel aging is possible for a low prediction error.

[0051] At block 26, wireless communications may be scheduled based on aging metrics. The aging metrics may each be associated with a corresponding channel associated with a UE antenna port. Data may then be wirelessly transmitted to at least some of the user equipment as part of the wireless communications. The wireless communications may be TDD MIMO wireless communications. Scheduling may include scheduling only UEs that have recently transmitted SRS, using SRS channel estimate aging in UE priority calculations, or scheduling fewer layers as channel estimate aging increases. Modulation and coding scheme selection for a group of user equipment scheduled during a time slot may be performed based on at least some of the aging metrics.

[0052] Although channel estimation aging may be discussed herein with reference to uplink SRS reception, any suitable principles and advantages disclosed herein may be applied to channel state information (CSI) measurements and / or data received by a base station from a UE. CSI may be obtained from feedback of UE measurements.

[0053] Figure 3 1 is a diagram illustrating a mapping of transmit groups to time slots for TDD wireless communications according to an embodiment, wherein UE antenna port scheduling has the latest SRS channel estimate. UEs 10A and 10B may each have four antenna ports. Antenna ports may be physical antennas. Transmit groups may be as described in reference Figure 1B The discussion is divided into. Before each time slot, the UE antenna port can transmit SRS. For example, SRS wirelessly transmitted from antenna ports P0 and P1 of the first UE 10A can be received before the first time slot. There is an SRS channel estimation processing delay between receiving the SRS and generating the channel estimate. After this processing delay, wireless communications associated with the channel can be scheduled.

[0054] exist Figure 3 In each time slot shown, a group of UE antenna ports with the latest SRS channel estimates are scheduled for wireless communication with the network. This can alleviate the channel aging problem by using new SRS channel estimates. The channel estimate generated based on the SRS received from antenna ports P0 and P1 of the first UE 10A is the latest for the first time slot. Wireless communication with antenna ports P0 and P1 of the first UE 10A can be scheduled for the first time slot. The channel estimate generated based on the SRS received from antenna ports P0 and P1 of the second UE 10B is the latest for the second time slot. Wireless communication with antenna ports P0 and P1 of the second UE 10B can be scheduled for the second time slot. The channel estimate generated based on the SRS received from antenna ports P2 and P3 of the first UE 10A is the latest for the third time slot. Wireless communication with antenna ports P2 and P3 of the first UE 10A can be scheduled for the third time slot. The channel estimate generated based on the SRS received from antenna ports P2 and P3 of the second UE 10B is the latest for the fourth time slot. Wireless communication with antenna ports P2 and P3 of the second UE 10B may be scheduled for the fourth time slot.

[0055] although Figure 3 is discussed with reference to time slots, but in some applications, Figure 3 One or more of a time slot may refer to a group of two or more time slots. A scheduling window may refer to one or more time slots in which one or more UEs are available for scheduling. Figure 8 and Fig. 9 An example scheduling window is discussed where multiple UEs may be scheduled during a number of time slots.

[0056] exist Figure 3 In the example of FIG. 1 , two UEs 10A and 10B with four antenna ports are grouped together for wireless communication. Any suitable number of UEs and / or antenna ports may be scheduled for a time slot of a particular application.

[0057] UE priority may be adjusted based on channel estimate aging. UE priority may be calculated based on one or more of the following data or quality of service (QoS) metrics of the application: traffic type, delay budget, reliability, or throughput / effective throughput. Channel estimate aging metrics may be incorporated into UE priority determination. Thus, aging metrics and one or more QoS indicators may be used to determine UE priority.

[0058] For example, user data may be classified into different queues based on one or more QoS indicators. UE priority may be determined based on queue priority, proportional fair scheduling (PFS) priority, and channel age priority. For example, for scheduling at time t+T using a channel estimate from time t, the UE priority may be expressed by Formula 1.

[0059]

[0060] In formula 1, is the PFS priority, calculated as the instantaneous achievable data rate r(t) and the average service data rate ratio, and the channel aging priority is a decreasing function of the channel aging τ.

[0061] The PFS priority may be intended to fairly distribute data rates between UEs. The PFS priority may be calculated as the ratio of the instantaneous data rate to the historical throughput. The channel aging priority may decrease as the utilized SRS channel estimate ages.

[0062] Figure 4A is a time diagram illustrating an example frame structure having a special time slot (S), an uplink time slot (U), and a downlink time slot (D). The example frame structure includes a special time slot, followed by 2 uplink time slots, and then 7 downlink time slots. Figure 4A As shown, SRS can be received in a special time slot. The SRS channel estimate can be used after a processing delay. For example, the SRS channel estimate can be ready for use Figure 4A The second downlink time slot of the example frame structure shown in .

[0063] The period of SRS transmission may vary over time. In some cases, SRS may be received from the antenna port of the UE every frame or period. In some other cases, SRS may be received from the antenna port of the UE every 4 frames or periods (e.g., in reference Figure 3 In the example discussed). As the time between SRS transmissions varies, the channel aging priority can be used to calculate the UE priority. Figure 4A In the present invention, the UE priority based on the channel aging priority can be used to schedule wireless communication in the downlink time slot. After the channel estimation and the corresponding channel aging priority, the channel aging priority can be used to determine which UEs and antenna ports are scheduled in the downlink time slot.

[0064] Figure 4Bis a graph illustrating an example channel aging priority over time. The channel aging priority may decrease monotonically with the time between consecutive SRS transmissions. The channel aging priority may be obtained through the corresponding SRS channel estimate.

[0065] The number of layers for MIMO communications may be reduced based on channel estimate aging. As channel estimates age, intra-cell interference may increase. As channel estimates age, the total number of scheduled layers for wireless communications per UE cluster may be reduced to mitigate intra-cell interference associated with channel estimate aging. In some applications, the total number of layers for wireless communications with a UE may be reduced based on aging of one or more channel estimates associated with the UE.

[0066] Figure 5A is a timing diagram illustrating an example frame structure with special time slots (S), uplink time slots (U), and downlink time slots (D). The maximum number of layers for wireless communication can be highest when the SRS channel estimate is ready for use. After the SRS channel estimate is ready, the maximum number of layers can decrease monotonically over time. As the uncertainty of the SRS channel estimate increases, the number of layers that can be used for wireless communication decreases. This can mitigate intra-cell interference associated with aging channel estimates. Figure 5A In the embodiment, as the channel estimate aging increases, wireless communications in the downlink time slot can be scheduled with fewer layers. For example, when the SRS channel estimate value is available, more layers can be scheduled in the second downlink time slot, and when the time after receiving the SRS is longer, fewer layers can be scheduled in the seventh downlink time slot.

[0067] Figure 5B is an example diagram illustrating the decrease in the number of wireless communication layers over time due to channel estimate aging. The maximum number of layers to be scheduled for each UE cluster decreases monotonically with the time between consecutive SRS transmissions. The maximum number of layers can be obtained using the corresponding SRS channel estimate for scheduling wireless communications with the UE cluster.

[0068] Various aspects of the present application relate to rate selection based on aging of SRS channel estimates. Such rate selection can mitigate the effects of channel estimate aging. A modulation and coding scheme (MCS) can be selected based on an aging metric. As the aging metric indicates more channel estimate aging, the MCS can be reduced. In some applications, the decibel backoff of the MCS can be proportional to the aging metric. MCS selection based on aging metric can be implemented by any suitable principles and advantages of SRS-aware scheduling disclosed herein. Considering the aging of SRS channel estimates in rate selection can be referred to as SRS-aware rate selection.

[0069] Figure 660 is a flow chart of a rate selection method 60 according to an embodiment. The UE may transmit the SRS wirelessly to the network system. In the method 60, any suitable principles and advantages discussed above may be used, for example, with reference to Figure 2 In the method 20 , a channel estimate is generated at block 22 , and an aging metric associated with the channel estimate may be determined at block 24 .

[0070] At block 64, MCS selection for the user equipment may be performed based on the aging metrics. The aging metrics may be at least some of the aging metrics determined at block 24.

[0071] MCS selection may include applying a backoff in the inner loop signal to interference plus noise ratio (SINR) calculation for the selected UE. The backoff may be in decibels (dB) and is proportional to the age of the SRS channel estimate used.

[0072] For MCS selection without considering SRS channel estimation aging, MCS can be based on inner loop SINR and ACK / NACK feedback from UE (outer loop). This MCS can be implemented according to formula 2.

[0073]

[0074] As an example, MCS(u) may be a function of the form shown in Equation 3. It can represent the backoff term due to ACK / NACK feedback from the UE.

[0075]

[0076] Even with SRS-aware scheduling, some UEs with high priority may still be scheduled despite the fact that the channel estimate is outdated. For example, UEs with high priority may be scheduled due to one or more of QoS, latency specifications, retransmissions, etc. The precoder and rate selection of these UEs may potentially be based on aged channel estimates. This may result in performance degradation. Therefore, SRS channel estimate aging may be considered in rate (e.g., MCS) selection. Aging metrics may be incorporated into MCS selection. MCS backoff may be applied in a manner proportional to SRS channel estimate aging and / or aging metrics in accordance with any suitable principles and advantages disclosed herein. The SRS-aware MCS selection may be performed according to formulas 4 and / or 5, where the aging backoff is an aging metric. Term It can represent the outer loop backoff term due to ACK / NACK feedback from the UE.

[0077]

[0078] For example, MCS(u) may be a function in the form shown in Formula 5.

[0079]

[0080] MCS selection may be applied with any suitable principles and advantages of SRS-aware scheduling disclosed herein.

[0081] The MCS selection may be performed for a UE scheduled for TDD MIMO communication in a particular time slot. The MCS selection may be performed for the scheduled UE based on the aging metric determined at block 24. After selecting the MCS, the network system may wirelessly communicate with the UE using the selected modulation and coding scheme. Such wireless communication may be TDD MIMO communication.

[0082] Figure 7 7 is a flow chart of a method 70 for scheduling wireless communications according to an embodiment. At block 72, a base station such as a gNodeB (gNB) may configure a UE for SRS transmission. The UEs and antenna ports may be divided into different transmission groups. An example of such division may include grouping the UEs and antenna ports, as described in reference to Figure 1A and 1B The UE may then wirelessly transmit the SRS at block 74. The antenna ports of the transmit group may transmit the SRS in corresponding time slots.

[0083] A baseband unit (BBU) of the base station may perform channel estimation based on the received SRS at block 75. For example, the gNB may perform channel estimation based on the SRS at a physical layer (PHY). The channel estimate may be stored in a cache with timing information such as a timestamp. The timing information indicates when the SRS was wirelessly transmitted. The timing information indicates when the SRS channel estimate was generated. The timing information indicates aging of the channel estimate.

[0084] The channel estimate and timing information may be provided to a scheduler of the BBU at block 76. The scheduler may be a medium access control (MAC) scheduler. The scheduler may be included in the gNB. The scheduler may perform scheduling and rate selection at block 78. Scheduling may involve selecting UEs and / or antenna ports for wireless communication in a particular time slot based on the channel estimate and timing information. Scheduling may be implemented using any suitable principles and advantages disclosed herein, for example, with reference to Figures 2 to 5B The scheduler may perform rate selection based on the channel estimate and the timing information. For example, MCS selection may be performed based on the channel estimate and a timestamp associated with the channel estimate. Rate selection may be implemented using any suitable principles and advantages disclosed herein, such as reference Figure 6 .

[0085] In some cases, UEs are scheduled regardless of channel aging to meet QoS parameters such as end-to-end delay or guaranteed bit rate (GBR). Scheduling UEs and / or antenna ports with the latest SRS channel estimates based solely on aging metrics may not be sufficient to handle such situations. Different approaches or combinations of approaches may be used to meet QoS parameters for these situations. The scheduler can handle these situations by trading off cell throughput to achieve the lowest QoS acceptance metric.

[0086] Figure 8 is a timing diagram illustrating processing retransmissions in SRS-aware scheduling according to an embodiment. In order to prioritize retransmissions to reduce and / or minimize latency, a combination of the above methods may be implemented. Figure 8 In the example shown, there are 6 UEs in the TDD system, each with 2 layers. A frame may include 10 time slots, time slot 0 to time slot 9. The UEs may be divided into two groups, each group sounding in a different special time slot. In time slot 0, UEs 0, 1, 2 transmit SRS. UEs 3, 4, 5 transmit SRS in time slot 10. SRS channel estimates may be prepared for UEs 0, 1, 2 at time slot 4.

[0087] UE 0, 1, 2 may be used to schedule wireless communications in time slots 4 to 9. For these time slots, UE 0, 1, and 2 with the latest SRS channel estimates may be scheduled during a scheduling window spanning time slots 4 to 9.

[0088] UE 4 may be in the retransmission queue for time slot 6. Due to being in the retransmission queue, the priority of UE 4 may be increased in time slot 6. An aging metric may be incorporated into the UE priority calculation. UE 4 may have a high priority for retransmission, and UEs 0, 1, and 2 may have a relatively high priority due to having newer SRS channel estimates. Due to the high priority of UE 4, it may be scheduled for retransmission in time slot 6. In time slot 6, two of UEs 0, 1, and 2 may also be scheduled for wireless communication.

[0089] As channel estimation aging increases, the number of scheduled layers can be reduced. In slots 4 to 6, 6 layers (3 UEs, 2 layers each) can be scheduled, while in slots 7 to 9, 4 layers (2 UEs, 2 layers each) can be scheduled.

[0090] Rate selection can take into account channel estimate aging. Figure 8 In , the MCS of the selected UE may be reduced in later downlink time slots relative to earlier time slots. Figure 8 In the example, the MCS of the selected UE can be backed off in each time slot.

[0091] Fig. 9is a timing diagram illustrating prioritization of UEs with guaranteed bit rate (GBR) QoS specification and SRS-aware scheduling according to an embodiment. In order to meet the GBR QoS specification and mitigate the channel aging effect, a combination of the above methods can be implemented. Fig. 9 In the example shown, there are 6 UEs in the TDD system, and each UE has 2 layers. UE 2 and 4 can be in the GBR queue.

[0092] A frame may include 10 time slots, time slot 0 to time slot 9. UEs may be divided into two groups, each group detecting in a different special time slot. In time slot 0, UEs 0, 1, 2 transmit SRS. UEs 3, 4, 5 transmit SRS in time slot 10. SRS channel estimates may be prepared for UEs 0, 1, 2 at time slot 4.

[0093] UE 0, 1, 2 may be used to schedule wireless communications in time slots 4 to 8. For these time slots, UE 0, 1, and 2 with the latest SRS channel estimates may be scheduled during a scheduling window spanning time slots 4 to 8.

[0094] UE 2 may meet its GBR specification in time slot 8. UE 4 may be in the GBR queue for time slot 9. An aging metric may be incorporated into the UE priority calculation. UE 4 may have a high priority to meet the GBR specification for time slot 9. UEs 0 and 1 may have a relatively high priority because they have updated SRS channel estimates and have one or more other parameters associated with a higher priority than UE 2. Due to the high priority of UE 4, it may be scheduled for wireless communication in time slot 9. UE 4 may meet its GBR specification with wireless communication in time slot 9. In time slot 9, UEs 0 and 1 are also scheduled for wireless communication.

[0095] Rate selection can take into account channel estimate aging. Fig. 9 In , the MCS of the selected UE may be reduced in later downlink time slots than in earlier time slots. Fig. 9 In the example, the MCS of the selected UE can be backed off in each time slot.

[0096] Downlink performance can be improved by maximizing the consistency between the actual channel and the assumed channel used for precoding. This can be achieved by using channel estimates and / or SRS predictions with reduced SRS aging. Aging reduction is possible if a subset of UEs are in high mobility and have highly aged channel estimates. When most or all UEs are in high mobility, a different approach may be advantageous.

[0097] It is desirable to have relatively constant SRS aging across downlink time slots. SRS aging may be more similar across downlink time slots with staggered SRS transmissions during uplink time slots. In some applications, SRS channel estimate aging may be relatively constant by performing SRS sounding in uplink time slots that are mapped one-to-one with downlink time slots. In such applications, UE scheduling in downlink time slots may be based on when the UE transmits SRS in an uplink time slot.

[0098] Although in some embodiments disclosed herein, the SRS is transmitted in a special time slot, the SRS may be transmitted in an uplink time slot alternatively or additionally. Transmitting the SRS in an uplink time slot may allow for staggered transmission of the SRS. Using staggered SRS transmissions, SRS channel estimates may be available at different times. Compared to SRS transmissions only in special time slots, there is a higher probability of obtaining minimum delay or reduced delay SRS estimates using staggered SRS transmissions. By scheduling wireless communications in downlink time slots based on aging according to the principles and advantages disclosed herein, staggered SRS channel estimates may improve downlink performance.

[0099] In an example method, SRS may be received from UEs in different uplink time slots. Channel estimates may be generated based on the SRS received in the different uplink time slots. Wireless communications may be scheduled using at least some of the user devices based on when sounding reference signals are received from at least some of the user devices.

[0100] Fig.10 is a timing diagram illustrating an example frame structure and staggered transmission of SRS. The diagram illustrates an example frame structure with 4 downlink time slots (D), 1 special time slot (S), and 5 uplink time slots (U). SRS can be wirelessly transmitted by the UE in different uplink time slots. For example, in Fig.10 In the example, SRS can be transmitted in 4 of 5 uplink time slots. One uplink time slot can include one or more SRS symbols. For example, 2 SRS symbols can be transmitted by the UE in an uplink time slot of 14 symbols. In this example, the uplink time slot can also include 1 physical uplink control channel (PUCCH) symbol and 11 physical uplink shared channel (PUSCH) symbols.

[0101] refer to Fig.10 , a first group of one or more UEs may transmit SRS during uplink time slot U6. An SRS channel estimate may be generated and may be used in downlink time slot D 10The other groups of one or more UEs may transmit SRS during uplink time slots U7, U8, and U9, and the corresponding channel SRS estimates may be used to transmit SRS during downlink time slots D, D, and D, respectively. 11 , D 12 and D 13 At the dispatch. Fig.10 In the example of , due to the SRS channel estimation processing delay, the SRS channel estimate is available four time slots after the SRS transmission.

[0102] Wireless communications and / or MCS selection may be scheduled based on the time delay of the SRS channel estimate. The time delay of the SRS channel estimate of the UE is an aging metric associated with the UE. Any suitable principles and advantages of using one or more aging metrics disclosed herein may be applied to the context of staggered SRS transmissions, such as Fig.10 When UEs transmit SRS in different time slots, UEs may be scheduled for downlink transmissions with less aged SRS transmissions. For example, a UE transmitting SRS in a first uplink time slot may be scheduled in a downlink time slot before another UE transmitting SRS in a second uplink time slot after the first uplink time slot.

[0103] Using staggered SRS transmissions, in some applications, the UE with the smallest delayed and / or smallest aged SRS channel estimate can be scheduled for downlink transmission. Fig.10 , a UE transmitting SRS during uplink time slot U7 can transmit SRS during downlink time slot D 10 Another UE that transmits SRS during uplink time slot U8 can be scheduled in downlink time slot D 11 is scheduled in, and so on. Fig.10 In the example of , an SRS channel estimate with minimum delay and / or minimum aging is available in each downlink timeslot. With more uplink timeslots, there are more opportunities for staggered SRS transmissions. Scheduling is not limited to downlink timeslots with minimum aging relative to SRS transmissions. Later timeslots with higher aging are also possible, but with corresponding performance tradeoffs. However, for a given downlink timeslot, staggered SRS transmissions increase the likelihood that the scheduler will find a UE with a more favorable aging metric in all timeslots.

[0104] In some applications, SRS may be transmitted in special time slots and uplink time slots. This may result in SRS estimates being available for scheduling at staggered times.

[0105] Depending on various applications, the SRS may be transmitted during one or more uplink time slots and become available during another uplink time slot before the first downlink time slot after the SRS transmission.

[0106] Any suitable principles and advantages disclosed herein may be implemented in a multi-cell and / or multi-transmit / receive point (TRP) network. In such a network, the TRP may be a gNB, a remote radio unit (RRU), or a relay node (e.g., an integrated access backhaul (IAB) node). The TRP may collaboratively transmit data to and / or receive data from the UE.

[0107] Fig.11 An example multi-TRP network 100 is illustrated. In the multi-TRP network 100, the network system includes a base station 102 and relay nodes 104A and 104B. UEs 10A, 10B, 10C, 10D, 10E, 10F communicate wirelessly with the network system in the multi-TRP network 100. SRS can be transmitted by UEs 10A to 10F to the base station 102. The transmission can be direct or with the aid of one or more relays 104A, 104B with a backhaul to the base station 102. There may be intra-cell interference between SRSs from different UEs 10A to 10F. Therefore, not all UEs 10A to 10F can transmit SRSs in every special time slot. UEs 10A to 10F and / or their antenna ports can be divided into different non-intersecting transmission groups. Any appropriate combination of the features of the methods disclosed herein can be applied to mitigate channel aging effects.

[0108] although Fig.11 Relay nodes 104A and 104B are illustrated, but any other suitable TRP may be implemented alternatively or additionally. Such other TRPs may coordinate transmission to and / or reception from the UE. In some cases, one or more relay nodes and one or more other TRPs may coordinate transmission to and / or reception from the UE.

[0109] The network system may be configured to schedule wireless communications and / or perform rate selection based on channel estimate aging according to any suitable principles and advantages disclosed herein.The network system may exchange TDD MIMO information with the UE. Fig.12 An example network system 110 is illustrated. The network system 110 may operate in any suitable network environment, such as Fig.13 network environment 230 and / or any suitable network environment.

[0110] Fig.121 is a block diagram illustrating an example network system 110 including a baseband unit (BBU) 112 and a remote radio unit (RRU) 130 according to an embodiment. The BBU 112 may schedule wireless communications and / or perform rate selection according to any suitable principles and advantages disclosed herein. The BBU 112 includes at least one processor and stores instructions that, when executed by the at least one processor, may cause the BBU 112 to perform any suitable baseband operation disclosed herein. The BBU 112 may be coupled to at least one remote radio unit 130. One or more remote radio units 130 may communicate wirelessly with a UE based on the scheduling and rate selection performed by the BBU 112. The BBU 112 may be coupled to multiple remote radio units 130, as shown. Such remote radio units 130 may be distributed. The remote radio units 130 and / or the fronthaul circuitry may perform radio frequency processing.

[0111] The remote radio unit 130 may include one or more antennas, such as at least a first antenna 142 and a second antenna 144, for wireless communication. The wireless communication may be, for example, TDD MIMO wireless communication. The remote radio unit 130 may include any appropriate number of antennas and / or antenna arrays. The antennas 142 and 144 of the RRU 130 are coupled to the transceiver 134. The transceiver 134 may perform any suitable radio frequency processing to support wireless communication. The transceiver 134 includes a receiver and a transmitter. The receiver may process signals received via antennas 142 and / or 144. The transceiver 134 may provide the processed signal to the RRU interface 128 included in the BBU 112. The transceiver 134 may include any appropriate number of receiving paths. The transmitter may process signals received from the BBU 112 to transmit via antennas 142 and / or 144. The transmitter of the transceiver 134 may provide signals to antennas 142 and / or 144 for transmission. The transceiver 134 may include any appropriate number of transmitting paths. Transceiver 134 may include different transmit and receive paths for each antenna 142 and 144 .

[0112] As shown, BBU 112 includes a processor 114, a channel estimator 116, a scheduler 118, a rate selector 120, a data memory 124, a beamformer 126, an RRU interface 128, and a bus 129. Bus 129 may couple several elements of BBU 112. Data may be communicated between elements of BBU 112 via bus 129.

[0113] The processor 114 may include any appropriate physical hardware configured to perform the functions described with reference to the processor 114. The processor 114 may manage communications between the network system 110 and the UE and / or network nodes. For example, the processor 114 may enable control information and data to be wirelessly sent to the UE via one or more RRUs 130. The processor 114 may include a processor, a microprocessor, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a programmable logic device (such as a field programmable gate array (FPGA)), etc., configured with specific executable instructions, or any combination thereof, which is designed to perform the functions described herein. In some applications, the processor 114 may be implemented by any suitable combination of a computing device and / or a discrete processing circuit.

[0114] The channel estimator 116 may generate a channel estimate based on a reference signal received from the UE. For example, the channel estimator 116 may generate a channel estimate based on an SRS received from the UE. The channel estimator 116 may generate channel estimates for various communication channels in a wireless communication environment. The channel estimator 116 may also generate timing information associated with the channel estimate. The channel estimator 116 may generate an aging metric associated with the channel estimate. The channel estimator 116 may be implemented by a dedicated circuit and / or by a circuit of the processor 114. In some cases, the channel estimator 116 may include a circuit for channel estimation of an SRS and / or a CSI-RS.

[0115] The scheduler 118 can schedule wireless communications between the network system 110 and the UE. The scheduler 118 can schedule wireless communications based on an aging metric associated with a channel estimate according to any appropriate principles and advantages disclosed herein. Such scheduling can involve scheduling only UEs and antenna ports with the latest channel estimates, using an aging metric in a user priority calculation, or reducing one or more of the number of layers wirelessly communicating with a UE cluster during a time slot based on an aging metric. The scheduler 118 can be implemented by dedicated circuits and / or circuits of the processor 114.

[0116] Rate selector 120 may perform user rate selection for wireless communications between network system 110 and a UE. Rate selector 120 may perform MCS selection based on an aging metric associated with a channel estimate in accordance with any suitable principles and advantages disclosed herein. The rate selection may involve backing off in the MCS based on an aging metric indicating that the channel estimate has aged. Rate selector 120 may be implemented by dedicated circuitry and / or circuitry of processor 114.

[0117] As shown, the processor 114 is in communication with a data memory 124. The data memory 124 may store instructions executable by one or more processors (e.g., including one or more of the processor 114, the channel estimator 116, the scheduler 118, or the rate selector 120) to implement any suitable combination of the features described herein. The data memory 124 may store information associated with one or more of an aging metric, user selections, user priorities, rate selections, etc. The data memory 124 may store any other suitable data for the BBU 112.

[0118] The beamformer 126 can generate parameters for the serving node of the UE. The parameters may include one or more of the transmission mode, time, frequency, power, beamforming matrix, tone allocation, or channel rank. The beamformer 126 can determine the desired and / or optimal parameters of the RRU 130 coupled to the BBU 112, which contributes to network-wide enhancement and / or optimization of downlink data transmission. Similar functions can be implemented to receive uplink data transmissions. The beamformer 126 is an example of an advanced precoding block that can enhance wireless communications in a TDD MTMO network. The beamformer 126 can generate a precoder that mitigates and / or eliminates intra-cell interference.

[0119] The processor 114 is shown in communication with an RRU interface 128. The RRU interface 128 may be any suitable interface for providing signals to and receiving signals from the RRU 130. As an example, the RRU interface 128 may be a common public radio interface.

[0120] Fig.13 2 is a diagram illustrating an example multiple-input multiple-output (MIMO) network environment 230 in which scheduling and / or rate selection based on channel estimate aging can be implemented. Various UEs can wirelessly communicate with a network system in the MIMO network environment 230. Such wireless communication can achieve high throughput. The wireless communication can be TDD communication. The antennas of the MIMO network environment 230 used for wireless communication with the UE can be distributed. Channel estimation of channels between different nodes can be performed based on SRS in the MIMO network environment 230. Scheduling and / or rate selection based on channel estimate aging according to any appropriate principles and advantages disclosed herein can be implemented in the MIMO network environment 230. The BBU 240 of the network system can perform such scheduling and / or rate selection.

[0121] Various standards and / or protocols may be implemented in the MIMO network environment 230 to communicate data wirelessly between a base station and a wireless communication device. Some wireless devices may communicate via a physical layer using an orthogonal frequency division multiplexing (OFDM) digital modulation scheme. Example standards and protocols for wireless communications in the network environment 230 may include the third generation partnership project (3GPP) long term evolution (LTE), long term evolution advanced (LTEAdvanced), 3GPP new air interface (NR) (also referred to as 5G), global mobile communication system (GSM), enhanced data rate GSM evolution (EDGE), global microwave access interoperability (WiMAX) and IEEE802.11 standards (may be referred to as Wi-Fi). In some systems, a radio access network (RAN) may include one or more base stations associated with one or more evolved node Bs (also commonly referred to as enhanced node Bs, eNodeBs or eNBs), gNBs or any other suitable node Bs (xNBs). In some other embodiments, a radio network controller (RNC) may be provided as a base station. A base station provides a bridge between a wireless network and a core network such as the Internet. A base station may be included to facilitate data exchange of wireless communication devices of a wireless network. The base station may determine an aging metric, perform scheduling, and perform rate selection according to any suitable principles and advantages disclosed herein.

[0122] A wireless communication device may be referred to as a user equipment (UE). A UE may be a device used by a user, such as a smartphone, a laptop, a tablet, a cellular phone, a wearable computing device (such as smart glasses or a smart watch or a headset), one or more networked devices (e.g., a consumer networked device or an industrial factory device), an industrial robot or a vehicle with connectivity. In some embodiments, a UE may include a sensor or other networked device configured to collect data and to provide the data wirelessly to a device (e.g., a server) connected to a core network (such as the Internet). Such a device may be referred to as an Internet of Things (IoT) device. Downlink (DL) transmissions typically refer to communications from a base transceiver station (BTS) or eNodeB to a UE. Uplink (UL) transmissions typically refer to communications from a UE to a BTS.

[0123] Fig.13 Illustrated is a collaborative or cloud radio access network (C-RAN) environment 230. In the network environment 230, eNodeB functionality is split between a baseband unit (BBU) 240 and a plurality of remote radio units (RRUs) (eg, RRU 255, RRU 265, and RRU 275). Fig.13The network system includes a BBU 240 and RRUs 255, 265, and 275. One RRU may include multiple antennas. RRUs and / or TRPs may be referred to as service nodes. BBU 240 may be physically connected to RRUs 255, 265, 275, for example, via an optical fiber connection. BBU 240 may provide operating information to the RRUs to control the transmission and reception of signals from the RRUs and control data and payload data to be transmitted. The RRUs may provide data received from UEs within a service area associated with the RRUs to the network. Fig.13 As shown, RRU 255 provides services to devices within service area 250. RRU 265 provides services to devices within service area 260. RRU 275 provides services to devices within service area 270. For example, wireless downlink transmission services may be provided to service area 270 to transmit data to one or more devices within service area 270.

[0124] In the network environment 230, the network system can communicate wirelessly with the UE via distributed MIMO. For example, UE 283 can communicate MIMO data wirelessly with antennas of the network system, and the antennas of the network system include at least one antenna of RRU 255, at least one antenna of RRU 265, and at least one antenna of RRU 275. As another example, UE 282 can communicate MIMO data wirelessly using distributed antennas, which include at least one antenna of RRU 255 and at least one antenna of RRU 265. As yet another example, UE 288 can communicate MIMO data wirelessly using distributed antennas, which include at least one antenna of RRU 255 and at least one antenna of RRU 275. For example, any suitable principles and advantages of reference signal channel estimation disclosed herein can be implemented in such distributed MIMO applications.

[0125] The illustrated RRUs 255, 265, and 275 include multiple antennas and can provide MIMO communications. For example, the RRUs can be equipped with various numbers of transmit antennas (e.g., 2, 4, 8, or more) that can be used to transmit to one or more receivers (such as UEs) simultaneously. The receiving device can include more than one receive antenna (e.g., 2, 4, etc.). The receive antenna array can be configured to simultaneously receive transmissions from the RRUs. Each antenna included in the RRU can be individually configured to transmit and / or receive according to a specific time, frequency, power, and direction configuration. Similarly, each antenna included in the UE can be individually configured to transmit and / or receive according to a specific time, frequency, power, and direction configuration. This configuration can be provided by the BBU 240.

[0126] Fig.13The service area shown can provide communication services to a heterogeneous group of user devices. For example, service area 250 can include a cluster of UEs 290, such as a group of devices associated with users attending a large event. Service area 250 can also include additional UEs 292 away from the cluster of UEs 290. Mobile user devices 294 can move from service area 260 to service area 270. Another example of a mobile user device is a vehicle 286, which can include a transceiver for wireless communication for real-time navigation, in-vehicle data services (e.g., streaming video or audio) or other data applications. Network environment 230 may include semi-mobile or fixed UEs configured for wireless communication, such as robotic devices 288 (e.g., robotic arms, autonomous drive units or other industrial or commercial robots) or televisions 284.

[0127] User equipment 282 may be located in an area with overlapping services (eg, service area 250 and service area 260). Each device in network environment 230 may have different performance requirements, which in some cases may conflict with the requirements of other devices.

[0128] Scheduling wireless communications and / or rate selection based on aging metrics according to any suitable principles and advantages disclosed herein may be performed in network environment 230. With such scheduling and / or rate selection, intra-cell interference may be reduced and / or mitigated.

[0129] Depending on the embodiment, certain actions, events, or functions of any method or algorithm described herein may be performed in a different order, may be added, combined, or omitted entirely (e.g., not all described operations or events are necessary for the practice of the method or algorithm). In addition, in some embodiments, operations or events may be performed concurrently, such as through multithreading, interrupt handling, or execution on multiple processors or processor cores or other parallel architectures, rather than sequentially.

[0130] Conditional language used herein, such as "can", "could", "might", "may", "eg", "such as", etc., unless otherwise explicitly stated or understood in the context of use, is generally intended to convey that certain embodiments include, while other embodiments do not include certain features, elements and / or operations. Therefore, such conditional language is generally not intended to imply that one or more embodiments require features, elements and / or operations in any way, or that one or more embodiments must include logic for determining whether these features, elements, and / or steps are included or will be performed in any particular embodiment with or without other input or prompts. The terms "comprising", "including", etc. are synonymous and are used in an inclusive, open-ended manner, and do not exclude additional elements, features, actions, operations, etc. In addition, when words such as "herein", "above", "below", and words of similar meaning are used in this application, they should refer to the application as a whole, not to any particular part of the application. Where the context permits, words used in the singular or plural in the above specific embodiments may also include the plural or singular, respectively. Additionally, the term "or" is used in an inclusive sense (rather than an exclusive sense) so that when used, for example, to connect a list of elements, the term "or" means one, some, or all of the elements in the list.

[0131] Unless expressly stated otherwise, subjunctive language such as the phrase "at least one of X, Y, Z" is generally understood in context to mean that an item, term, etc. may be X, Y, or Z, or any combination thereof (e.g., X, Y, and / or Z). Thus, such disjunctive language is generally not intended to, and should not, imply that certain embodiments require that at least one of X, at least one of Y, or at least one of Z all be present.

[0132] Unless expressly specified otherwise or generally understood from the context, the term "a" or "an" should generally be interpreted as including one or more of the items described. Therefore, a phrase such as "a device configured to" is intended to include one or more of the devices described. Such one or more devices may also be collectively configured to perform the described clauses. For example, "a processor configured to perform clauses A, B, and C" may include a first processor configured to perform clause A, which works in conjunction with a second processor configured to perform clause B and C.

[0133] As generally used herein, the word "coupled" refers to two or more elements that can be coupled to each other directly or through one or more intermediate elements. Likewise, as generally used herein, the word "connected" refers to two or more elements that can be connected directly or through one or more intermediate elements. The connection can be via an air interface and / or via wires and / or optical fibers and / or any other suitable connection.

[0134] As used herein, the term "determining" or "determining" includes a variety of actions. For example, "determining" may include calculating, computing, processing, deriving, generating, obtaining, searching (e.g., searching in a table, database, or another data structure), determining by a hardware element without user intervention, etc. In addition, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), etc. via a hardware element without user intervention. In addition, "determining" may include parsing, selecting, choosing, establishing, etc. by a hardware element without user intervention.

[0135] Although the above detailed description has shown, described and pointed out the novel features applied to various embodiments, it is understood that various omissions, substitutions and changes may be made to the form and details of the illustrated devices or algorithms without departing from the spirit of the present disclosure. For example, the circuit blocks and / or method blocks described herein may be deleted, moved, added, subdivided, combined, arranged in different orders and / or modified. Each of these blocks may be implemented in various different ways. Any part of any method disclosed herein may be performed in association with specific instructions stored on a non-transitory computer-readable storage medium executed by one or more processors. As can be appreciated, certain embodiments described herein may be embodied in a form that does not provide all the features and benefits set forth herein, because some features may be used or practiced separately from other features. The scope of certain embodiments disclosed herein is indicated by the appended claims rather than by the foregoing description. All changes within the meaning and equivalent scope of the claims should be included within their scope.

Claims

1. A method for scheduling wireless communications based on channel estimation aging, the method comprising: generating a channel estimate based on a signal wirelessly transmitted by a user equipment; determining an aging metric associated with the channel estimate; as well as Wireless communications with at least some of the user equipment are scheduled based on the aging metric.

2. The method of claim 1, wherein: The signal wirelessly transmitted by the user equipment is a sounding reference signal.

3. The method of claim 2, wherein: A first one of the sounding reference signals is wirelessly transmitted by a first one of the user equipments in a first time slot, and a second one of the sounding reference signals is wirelessly transmitted by a second one of the user equipments in a second time slot, the second time slot following the first time slot.

4. The method of claim 1, wherein: The wireless communication is a time division duplex (TDD) multiple input multiple output (MIMO) wireless communication.

5. The method of claim 1, wherein: One of the aging metrics is based solely on a time delay associated with a corresponding channel estimate.

6. The method of claim 1, wherein: One of the aging metrics is based on mobility of a channel associated with a corresponding channel estimate and a time delay associated with the corresponding channel estimate.

7. The method of claim 1, wherein: One of the aging metrics is based on a channel quality prediction associated with a corresponding channel estimate and a time delay associated with the corresponding channel estimate.

8. The method of claim 1, wherein: The scheduling includes selecting a first group of antenna ports of the user equipment for wireless communication during a time slot based on a corresponding first aging metric among the aging metrics indicating lower channel uncertainty, and not scheduling a second group of antenna ports of the user equipment for wireless communication during the time slot based on a corresponding second aging metric among the aging metrics indicating high channel uncertainty.

9. The method of claim 8, wherein: The scheduling includes using at least some of the aging metrics to determine user equipment priorities for time slots.

10. The method of claim 9, wherein: The scheduling includes reducing a number of layers of the wireless communication used for a time slot.

11. The method of claim 8, wherein: The scheduling includes reducing the number of layers used for wireless communication in the time slot.

12. The method of claim 1, wherein: The scheduling includes using at least some of the aging metrics to determine user equipment priorities for time slots.

13. The method of claim 12, wherein: The determining of the user equipment priority of the time slot is also based on one or more quality of service metrics.

14. The method of claim 12, wherein: The scheduling includes reducing the number of layers used for wireless communication in the time slot.

15. The method of claim 1, wherein: The scheduling includes reducing the number of layers used for wireless communication in the time slot.

16. The method of claim 1, further comprising: Based on at least some of the aging metrics, modulation and coding scheme selection is performed for a set of antenna ports of the user equipment scheduled for a time slot.

17. A non-transitory computer-readable memory comprising computer-executable instructions, wherein: When executed by a baseband unit, a method is performed, the method comprising: generating a channel estimate based on a signal wirelessly transmitted by a user equipment; determining an aging metric associated with the channel estimate; and Wireless communications with at least some of the user equipment are scheduled based on the aging metric.

18. A system for wireless communication, the system comprising: A baseband unit, comprising at least one processor and storing instructions, wherein when executed by the at least one processor, the baseband unit is caused to perform operations, the operations comprising: generating a channel estimate based on a signal received from a user equipment; determining an aging metric associated with the channel estimate; and Wireless communications with at least some of the user equipment are scheduled based on the aging metric.

19. The system of claim 18, further comprising: One or more radio units in communication with the baseband unit, the one or more radio units configured to wirelessly communicate with at least some of the user devices via the wireless communication.

20. The system of claim 19, wherein: The one or more radio units include distributed remote radio units.

Images