WO2021123931A1

WO2021123931A1 - Switching between single layer and multilayer transmission

Info

Publication number: WO2021123931A1
Application number: PCT/IB2020/058676
Authority: WO
Inventors: Amr El-Keyi; Chandra Bontu
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-12-19
Filing date: 2020-09-17
Publication date: 2021-06-24

Abstract

An apparatus, a method, and a computer storage medium for switching between single layer and multilayer uplink transmission are disclosed. According to one aspect, a network node comprises processing circuitry configured to measure a received signal quality of a scheduled uplink transmission from a wireless device, WD, and to determine a signal quality metric for a single layer reception and a signal quality metric for a multilayer reception based on the measured received signal quality. The processing circuitry is further configured to determine a relationship at least between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception and to determine a number of layers for a next uplink transmission from the WD based on the determined relationship.

Description

SWITCHING BETWEEN SINGLE LAYER AND MULTILAYER

TRANSMISSION

TECHNICAL FIELD

The present disclosure relates to wireless communications, and in particular, to switching between single layer and multilayer transmission.

BACKGROUND

Spatial multiplexing can provide significant capacity improvements to wireless cellular systems by transmitting multiple spatial layers (data streams) on the same time-frequency resources when the user equipment (UE) or wireless device (WD) is in good radio conditions. In single user multiple input multiple output (SU- MIMO) transmission, multiple layers are scheduled simultaneously to a single user. These layers are spatially multiplexed by mapping the transmitted layers to the available transmit antennas using a precoder. In this case, the transmission power is shared among the transmitted layers resulting in a lower received signal to interference-plus-noise ratio (SINR) per transmission layer than that of single-layer transmission. Nevertheless, when the WD is in good radio conditions, the multiplicative throughput gain due to multi-layer transmission exceeds the throughput loss due to SINR reduction per layer leading to spatial multiplexing capacity gains.

Fifth Generation (5G) wireless systems, also called New Radio (NR), refer to a wireless communication system under development by the Third Generation Partnership Project (3GPP). In NR, uplink SU-MIMO can be implemented via codebook-based precoding where the uplink precoding matrix is selected from a finite set of available precoders. The uplink precoder is chosen by the network node and signaled to the wireless device (WD) in the uplink grant. Several methods have been proposed for selecting the number of layers and the uplink precoding matrix for SU- MIMO transmission. These methods rely on collecting information about the uplink channel state and processing this information to determine the transmission rank, i.e., the number of uplink layers, and the uplink precoding matrix. Performing this task requires changing the uplink transmission rank and repeatedly switching the transmission mode of the uplink between single-layer and multi-layer transmission. For example, in order to allow continuous tracking of the statistics corresponding to each transmission rank hypothesis, some proposed algorithms use periodic rank polling to force scheduling uplink transmissions with various number of layers. In addition, in order to estimate the uplink transmit covariance matrix, a switching mechanism has been proposed to periodically switch between exploration mode where the number of layers and the precoder are selected for the purpose of improving the current covariance estimate and exploitation mode where the precoder is selected to maximize the throughput gain using the current channel covariance estimate.

Existing solutions for codebook-based uplink SU-MIMO rank and precoder selection may require repeatedly switching the transmission mode of the uplink between single-layer and multi-layer transmission in order to track the channel statistics corresponding to different transmission rank hypotheses. This may cause throughput loss as non-optimal transmission ranks must be periodically scheduled for the uplink especially when the WD mobility increases. In addition, switching the transmission mode of the WD between single layer and multi-layer transmission may require exchanging higher-layer messages between WD and the network node, resulting in additional delay and performance loss.

SUMMARY

Some embodiments of the present disclosure advantageously provide methods, systems, and apparatuses for switching between single layer and multilayer uplink transmission.

Some embodiments are applicable to NR as well as Long Term Evolution (LTE) (which is a currently extant wireless communication system according to standards developed by the 3GPP) and NR. Some embodiments switch between single-layer and multi-layer uplink transmission modes such to maximize a signal quality metric. For example, the network node, e.g., access node, can adaptively switch between single layer and multilayer uplink (UL) transmission by:

(1) measuring a received signal quality of a scheduled UL transmission;

(2) computing a signal quality metric for single layer reception and multilayer reception based on the measured received signal quality; (3) computing a ratio of maximum signal quality metric for multilayer reception to the signal quality of a single layer reception; and

(4) determining layers for the next UL transmission based on the computed ratio. According to some embodiments, the received signal quality is in the form of a SINR. The signal quality metric is uplink information carrying capacity (ICC), i.e., the number of bits that can be correctly decoded with the target error rate at the network node. Switching may be done based on the filtered ICC ratio, i.e., the ratio between the ICC of multi-layer transmission and that of single layer transmission. For each uplink reception, the ICC ratio is updated by using the information collected from processing the current uplink reception. Hence, some embodiments do not require scheduling uplink transmissions for the purpose of tracking the channel statistics corresponding to different uplink transmission rank hypotheses. Switching may be performed in some embodiments by comparing the filtered ICC ratio to an upper and a lower threshold and maintaining the same transmission mode as that in the previous uplink transmission if the filtered ICC ratio lies between the two thresholds. This reduces the number of switching events and avoids repeated switching back and forth between the two transmission modes. Simulation results show the ability of some embodiments to improve both the average uplink cell throughput and the cell edge throughput compared to known algorithms. This may be achieved, for example, by switching to multi-layer transmission when the WD is in good radio conditions and maintaining single layer transmission when the radio condition of the WD deteriorates. According to one aspect of the present disclosure, a network node configured to communicate with a wireless device, WD, is provided. The network node includes processing circuitry that is configured to measure a received signal quality of a scheduled uplink transmission from the WD and to determine a signal quality metric for a single layer reception and a signal quality metric for a multilayer reception based on the measured received signal quality. The processing circuitry is further configured to determine a relationship at least between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception and to determine a number of layers for a next uplink transmission from the WD based on the determined relationship. In some embodiments, the relationship is a ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception, the signal quality metric for the multilayer reception being based at least on uplink information carrying capacity, ICC, for the multilayer reception, and the signal quality metric for the single layer reception being based at least on uplink ICC for the single layer reception. In some other embodiments, the determined number of layers for the next uplink transmission maximizes the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception. In other embodiments, the determined number of layers for the next uplink transmission is selected based at least on the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception.

In another embodiment, the determined number of layers is one of greater than 1 if the determined relationship is greater than an upper threshold, unchanged if the determined relationship is within the upper threshold and a lower threshold, and equal to 1 if the determined relationship is less than the lower threshold. In some embodiments, the processing circuitry is further configured to select an uplink precoder from a precoder codebook based on the determined number of layers when the determined number of layers is greater than 1.

In some other embodiments, the processing circuitry is further configured to determine a rank hypothesis based at least on the measured received signal quality and determine an ICC estimation based at least on the rank hypothesis without scheduling an uplink transmission. In another embodiment, determining the ICC estimation is further based on at least one of a rank of an uplink reception from the WD, an uplink interference estimation, an uplink power control state, an uplink channel quality estimation, and an average signal to noise ratio, SINR.

In some other embodiments, the determination of the relationship between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception is further based at least in part on the determined ICC estimation. In another embodiment, the processing circuitry is further configured to determine a modulation and coding scheme, MCS, to be utilized by the WD in the next uplink transmission, the determined MCS being based at least on the determined ICC estimation. In another embodiment, the processing circuitry is further configured to cause one of a single layer transmission by the WD and a multilayer transmission by the WD based at least on the determined number of layers. According to another aspect of the present disclosure, a method for a network node to determine a transmission mode for communication with a wireless device, WD, is provided. The method includes measuring a received signal quality of a scheduled uplink transmission from the WD and determining a signal quality metric for a single layer reception and a signal quality metric for a multilayer reception based on the measured received signal quality. The method further includes determining a relationship at least between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception and determining a number of layers for a next uplink transmission from the WD based on the determined relationship.

In some embodiments, the relationship is a ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception, the signal quality metric for the multilayer reception being based at least on uplink information carrying capacity, ICC, for the multilayer reception, and the signal quality metric for the single layer reception being based at least on uplink ICC for the single layer reception. In some other embodiments, the determined number of layers for the next uplink transmission maximizes the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception. In some other embodiments, the determined number of layers for the next uplink transmission is based at least on the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception.

In another embodiment, the determined number of layers is one of greater than 1 if the determined relationship is greater than an upper threshold, unchanged if the determined relationship is within the upper threshold and a lower threshold, and equal to 1 if the determined relationship is less than the lower threshold. In some embodiments, the method further includes selecting an uplink precoder from a precoder codebook based on the determined number of layers when the determined number of layers is greater than 1.

In some other embodiments, the method further includes determining a rank hypothesis based at least on the measured received signal quality and determining an ICC estimation based at least on the rank hypothesis without scheduling an uplink transmission. In another embodiment, determining the ICC estimation is further based on at least one of a rank of an uplink reception from the WD, an uplink interference estimation, an uplink power control state, an uplink channel quality estimation, and an average signal to noise ratio, SINR.

In some other embodiments, the determination of the relationship between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception is further based at least in part on the determined ICC estimation. In another embodiment, the method further includes determining a modulation and coding scheme, MCS, to be utilized by the WD in the next uplink transmission, the determined MCS being based at least on the determined ICC estimation. In another embodiment, the method further includes causing one of a single layer transmission by the WD and a multilayer transmission by the WD based at least on the determined number of layers.

According to another aspect of the present disclosure, a computer storage medium storing an executable computer program is provided. When executable computer program is executed by processing circuitry, the executable computer program causes the processing circuitry to at least one of perform and control a method according to and one of Claims 11-20.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments, and the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic diagram of an example network architecture illustrating a communication system connected via an intermediate network to a host computer according to the principles in the present disclosure; FIG. 2 is a block diagram of a host computer communicating via a network node with a wireless device over an at least partially wireless connection according to some embodiments of the present disclosure;

FIG. 3 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for executing a client application at a wireless device according to some embodiments of the present disclosure;

FIG. 4 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a wireless device according to some embodiments of the present disclosure;

FIG. 5 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data from the wireless device at a host computer according to some embodiments of the present disclosure; FIG. 6 is a flowchart illustrating example methods implemented in a communication system including a host computer, a network node and a wireless device for receiving user data at a host computer according to some embodiments of the present disclosure; FIG. 7 is a flowchart of an example process in a network node for switching between single layer and multilayer uplink transmission according to some embodiments of the present disclosure;

FIG. 8 is a flowchart of another example process in a network node for switching between single layer and multilayer uplink transmission according to some embodiments of the present disclosure;

FIG. 9 is block diagram of one example embodiment for switching between single layer and multilayer uplink transmission;

FIG. 10 is a block diagram of one example embodiment for computation of signal quality metric; FIG. 11 is a block diagram of one example embodiment for computation of ratio of maximum signal quality metric for multilayer reception to the signal quality of a single layer reception;

FIG. 12 is a graph of simulation results for one embodiment according to principles set forth herein; FIG. 13 is a graph of simulation results for one embodiment according to principles set forth herein;

FIG. 14 is a graph of simulation results for one embodiment according to principles set forth herein; and

FIG. 15 is a graph of simulation results for one embodiment according to principles set forth herein.

DETAILED DESCRIPTION

Before describing in detail example embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to switching between single layer and multilayer uplink transmission. Accordingly, components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Like numbers refer to like elements throughout the description.

As used herein, relational terms, such as “first” and “second,” “top” and “bottom,” and the like, may be used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the concepts described herein. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms

“comprises,” “comprising,” “includes” and/or “including” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. In embodiments described herein, the joining term, “in communication with” and the like, may be used to indicate electrical or data communication, which may be accomplished by physical contact, induction, electromagnetic radiation, radio signaling, infrared signaling or optical signaling, for example. One having ordinary skill in the art will appreciate that multiple components may interoperate and modifications and variations are possible of achieving the electrical and data communication.

In some embodiments described herein, the term “coupled,” “connected,” and the like, may be used herein to indicate a connection, although not necessarily directly, and may include wired and/or wireless connections. The term “network node” used herein can be any kind of network node comprised in a radio network which may further comprise any of base station (BS), radio base station, base transceiver station (BTS), base station controller (BSC), radio network controller (RNC), g Node B (gNB), evolved Node B (eNB or eNodeB), Node B, multi- standard radio (MSR) radio node such as MSR BS, multi-cell/multicast coordination entity (MCE), integrated access and backhaul (IAB) node, relay node, donor node controlling relay, radio access point (AP), transmission points, transmission nodes, Remote Radio Unit (RRU) Remote Radio Head (RRH), a core network node (e.g., mobile management entity (MME), self-organizing network (SON) node, a coordinating node, positioning node, MDT node, etc.), an external node (e.g., 3rd party node, a node external to the current network), nodes in distributed antenna system (DAS), a spectrum access system (SAS) node, an element management system (EMS), etc. The network node may also comprise test equipment. The term “radio node” used herein may be used to also denote a wireless device (WD) such as a wireless device (WD) or a radio network node.

In some embodiments, the non-limiting terms wireless device (WD) or a user equipment (UE) are used interchangeably. The WD herein can be any type of wireless device capable of communicating with a network node or another WD over radio signals, such as wireless device (WD). The WD may also be a radio communication device, target device, device to device (D2D) WD, machine type WD or WD capable of machine to machine communication (M2M), low-cost and/or low-complexity WD, a sensor equipped with WD, Tablet, mobile terminals, smart phone, laptop embedded equipped (LEE), laptop mounted equipment (LME), USB dongles, Customer Premises Equipment (CPE), an Internet of Things (IoT) device, or a Narrowband IoT (NB-IOT) device etc.

Also, in some embodiments the generic term “radio network node” is used. It can be any kind of a radio network node which may comprise any of base station, radio base station, base transceiver station, base station controller, network controller, RNC, evolved Node B (eNB), Node B, gNB, Multi-cell/multicast Coordination Entity (MCE), IAB node, relay node, access point, radio access point, Remote Radio Unit (RRU) Remote Radio Head (RRH).

Note that although terminology from one particular wireless system, such as, for example, 3GPP LTE and/or New Radio (NR), may be used in this disclosure, this should not be seen as limiting the scope of the disclosure to only the aforementioned system. Other wireless systems, including without limitation Wide Band Code Division Multiple Access (WCDMA), Worldwide Interoperability for Microwave Access (WiMax), Ultra Mobile Broadband (UMB) and Global System for Mobile Communications (GSM), may also benefit from exploiting the ideas covered within this disclosure. Note further, that functions described herein as being performed by a wireless device or a network node may be distributed over a plurality of wireless devices and/or network nodes. In other words, it is contemplated that the functions of the network node and wireless device described herein are not limited to performance by a single physical device and, in fact, can be distributed among several physical devices.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Some embodiments provide switching between single layer and multilayer uplink transmission. Some embodiments, can adaptively select the number of layers for uplink transmission based only on the information provided from uplink receptions and do not need scheduling of uplink transmissions to update the channel statistics.

Some embodiments provide improvements in both the average uplink cell throughput and the cell edge throughput compared to previous algorithms by selecting the transmission rank of each WD based on its radio conditions.

Some embodiments avoid repeatedly switching back and forth between single layer and multi-layer transmission modes. Hence, embodiments avoid the delay and throughput loss that occur when switching is done using higher layer messages exchanged between the WD and the network node.

Referring now to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 1 a schematic diagram of a communication system 10, according to an embodiment, such as a 3GPP-type cellular network that may support standards such as LTE and/or NR (5G), which comprises an access network 12, such as a radio access network, and a core network 14. The access network 12 comprises a plurality of network nodes 16a, 16b, 16c (referred to collectively as network nodes 16), such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area 18a, 18b, 18c (referred to collectively as coverage areas 18). Each network node 16a, 16b, 16c is connectable to the core network 14 over a wired or wireless connection 20. A first wireless device (WD) 22a located in coverage area 18a is configured to wirelessly connect to, or be paged by, the corresponding network node 16a. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node 16b. While a plurality of WDs 22a, 22b (collectively referred to as wireless devices 22) are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole WD is in the coverage area or where a sole WD is connecting to the corresponding network node 16. Note that although only two WDs 22 and three network nodes 16 are shown for convenience, the communication system may include many more WDs 22 and network nodes 16.

Also, it is contemplated that a WD 22 can be in simultaneous communication and/or configured to separately communicate with more than one network node 16 and more than one type of network node 16. For example, a WD 22 can have dual connectivity with a network node 16 that supports LTE and the same or a different network node 16 that supports NR. As an example, WD 22 can be in communication with an eNB for LTE/E-UTRAN and a gNB for NR/NG-RAN.

The communication system 10 may itself be connected to a host computer 24, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 24 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service provider. The connections 26, 28 between the communication system 10 and the host computer 24 may extend directly from the core network 14 to the host computer 24 or may extend via an optional intermediate network 30. The intermediate network 30 may be one of, or a combination of more than one of, a public, private or hosted network. The intermediate network 30, if any, may be a backbone network or the Internet. In some embodiments, the intermediate network 30 may comprise two or more sub-networks (not shown).

The communication system of FIG. 1 as a whole enables connectivity between one of the connected WDs 22a, 22b and the host computer 24. The connectivity may be described as an over-the-top (OTT) connection. The host computer 24 and the connected WDs 22a, 22b are configured to communicate data and/or signaling via the OTT connection, using the access network 12, the core network 14, any intermediate network 30 and possible further infrastructure (not shown) as intermediaries. The OTT connection may be transparent in the sense that at least some of the participating communication devices through which the OTT connection passes are unaware of routing of uplink and downlink communications. For example, a network node 16 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 24 to be forwarded (e.g., handed over) to a connected WD 22a. Similarly, the network node 16 need not be aware of the future routing of an outgoing uplink communication originating from the WD 22a towards the host computer 24.

A network node 16 is configured to include a ratio determiner 32 which is configured to determine a ratio of a signal quality for multilayer reception to a signal quality of single layer reception. The ratio determiner 32 may reside in one of the network nodes 16, when WD is simultaneously communicating with more than one network nodes.

Example implementations, in accordance with an embodiment, of the WD 22, network node 16 and host computer 24 discussed in the preceding paragraphs will now be described with reference to FIG. 2. In a communication system 10, a host computer 24 comprises hardware (HW) 38 including a communication interface 40 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 10. The host computer 24 further comprises processing circuitry 42, which may have storage and/or processing capabilities. The processing circuitry 42 may include a processor 44 and memory 46. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 42 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 44 may be configured to access (e.g., write to and/or read from) memory 46, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read- Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Processing circuitry 42 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by host computer 24. Processor 44 corresponds to one or more processors 44 for performing host computer 24 functions described herein. The host computer 24 includes memory 46 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 48 and/or the host application 50 may include instructions that, when executed by the processor 44 and/or processing circuitry 42, causes the processor 44 and/or processing circuitry 42 to perform the processes described herein with respect to host computer 24. The instructions may be software associated with the host computer 24.

The software 48 may be executable by the processing circuitry 42. The software 48 includes a host application 50. The host application 50 may be operable to provide a service to a remote user, such as a WD 22 connecting via an OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the remote user, the host application 50 may provide user data which is transmitted using the OTT connection 52. The “user data” may be data and information described herein as implementing the described functionality. In one embodiment, the host computer 24 may be configured for providing control and functionality to a service provider and may be operated by the service provider or on behalf of the service provider. The processing circuitry 42 of the host computer 24 may enable the host computer 24 to observe, monitor, control, transmit to and/or receive from the network node 16 and or the wireless device 22.

The communication system 10 further includes a network node 16 provided in a communication system 10 and including hardware 58 enabling it to communicate with the host computer 24 and with the WD 22. The hardware 58 may include a communication interface 60 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 10, as well as a radio interface 62 for setting up and maintaining at least a wireless connection 64 with a WD 22 located in a coverage area 18 served by the network node 16. The radio interface 62 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers. The communication interface 60 may be configured to facilitate a connection 66 to the host computer 24. The connection 66 may be direct or it may pass through a core network 14 of the communication system 10 and/or through one or more intermediate networks 30 outside the communication system 10.

In the embodiment shown, the hardware 58 of the network node 16 further includes processing circuitry 68. The processing circuitry 68 may include a processor 70 and a memory 72. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 68 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 70 may be configured to access (e.g., write to and/or read from) the memory 72, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the network node 16 further has software 74 stored internally in, for example, memory 72, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the network node 16 via an external connection. The software 74 may be executable by the processing circuitry 68. The processing circuitry 68 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by network node 16. Processor 70 corresponds to one or more processors 70 for performing network node 16 functions described herein. The memory 72 is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 74 may include instructions that, when executed by the processor 70 and/or processing circuitry 68, causes the processor 70 and/or processing circuitry 68 to perform the processes described herein with respect to network node 16. For example, processing circuitry 68 of the network node 16 may include a ratio determiner 32 which is configured to determine a ratio of a signal quality for multilayer reception to a signal quality of single layer reception.

The communication system 10 further includes the WD 22 already referred to. The WD 22 may have hardware 80 that may include a radio interface 82 configured to set up and maintain a wireless connection 64 with a network node 16 serving a coverage area 18 in which the WD 22 is currently located. The radio interface 82 may be formed as or may include, for example, one or more RF transmitters, one or more RF receivers, and/or one or more RF transceivers.

The hardware 80 of the WD 22 further includes processing circuitry 84. The processing circuitry 84 may include a processor 86 and memory 88. In particular, in addition to or instead of a processor, such as a central processing unit, and memory, the processing circuitry 84 may comprise integrated circuitry for processing and/or control, e.g., one or more processors and/or processor cores and/or FPGAs (Field Programmable Gate Array) and/or ASICs (Application Specific Integrated Circuitry) adapted to execute instructions. The processor 86 may be configured to access (e.g., write to and/or read from) memory 88, which may comprise any kind of volatile and/or nonvolatile memory, e.g., cache and/or buffer memory and/or RAM (Random Access Memory) and/or ROM (Read-Only Memory) and/or optical memory and/or EPROM (Erasable Programmable Read-Only Memory).

Thus, the WD 22 may further comprise software 90, which is stored in, for example, memory 88 at the WD 22, or stored in external memory (e.g., database, storage array, network storage device, etc.) accessible by the WD 22. The software 90 may be executable by the processing circuitry 84. The software 90 may include a client application 92. The client application 92 may be operable to provide a service to a human or non-human user via the WD 22, with the support of the host computer 24. In the host computer 24, an executing host application 50 may communicate with the executing client application 92 via the OTT connection 52 terminating at the WD 22 and the host computer 24. In providing the service to the user, the client application 92 may receive request data from the host application 50 and provide user data in response to the request data. The OTT connection 52 may transfer both the request data and the user data. The client application 92 may interact with the user to generate the user data that it provides.

The processing circuitry 84 may be configured to control any of the methods and/or processes described herein and/or to cause such methods, and/or processes to be performed, e.g., by WD 22. The processor 86 corresponds to one or more processors 86 for performing WD 22 functions described herein. The WD 22 includes memory 88 that is configured to store data, programmatic software code and/or other information described herein. In some embodiments, the software 90 and/or the client application 92 may include instructions that, when executed by the processor 86 and/or processing circuitry 84, causes the processor 86 and/or processing circuitry 84 to perform the processes described herein with respect to WD 22.

In some embodiments, the inner workings of the network node 16, WD 22, and host computer 24 may be as shown in FIG. 2 and independently, the surrounding network topology may be that of FIG. 1.

In FIG. 2, the OTT connection 52 has been drawn abstractly to illustrate the communication between the host computer 24 and the wireless device 22 via the network node 16, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the WD 22 or from the service provider operating the host computer 24, or both. While the OTT connection 52 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network).

The wireless connection 64 between the WD 22 and the network node 16 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the WD 22 using the OTT connection 52, in which the wireless connection 64 may form the last segment. More precisely, the teachings of some of these embodiments may improve the data rate, latency, and/or power consumption and thereby provide benefits such as reduced user waiting time, relaxed restriction on file size, better responsiveness, extended battery lifetime, etc.

In some embodiments, a measurement procedure may be provided for the purpose of monitoring data rate, latency and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 52 between the host computer 24 and WD 22, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 52 may be implemented in the software 48 of the host computer 24 or in the software 90 of the WD 22, or both. In embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 52 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software 48, 90 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 52 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the network node 16, and it may be unknown or imperceptible to the network node 16. Some such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary WD signaling facilitating the host computer’s 24 measurements of throughput, propagation times, latency and the like. In some embodiments, the measurements may be implemented in that the software 48, 90 causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 52 while it monitors propagation times, errors etc.

Thus, in some embodiments, the host computer 24 includes processing circuitry 42 configured to provide user data and a communication interface 40 that is configured to forward the user data to a cellular network for transmission to the WD 22. In some embodiments, the cellular network also includes the network node 16 with a radio interface 62. In some embodiments, the network node 16 is configured to, and/or the network node’s 16 processing circuitry 68 is configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the WD 22, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the WD 22.

In some embodiments, the host computer 24 includes processing circuitry 42 and a communication interface 40 that is configured to a communication interface 40 configured to receive user data originating from a transmission from a WD 22 to a network node 16. In some embodiments, the WD 22 is configured to, and/or comprises a radio interface 82 and/or processing circuitry 84 configured to perform the functions and/or methods described herein for preparing/initiating/maintaining/supporting/ending a transmission to the network node 16, and/or preparing/terminating/maintaining/supporting/ending in receipt of a transmission from the network node 16.

Although FIGS. 1 and 2 show various “units” such as the ratio determiner 32 as being within a respective processor, it is contemplated that these units may be implemented such that a portion of the unit is stored in a corresponding memory within the processing circuitry. In other words, the units may be implemented in hardware or in a combination of hardware and software within the processing circuitry.

FIG. 3 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIGS. 1 and 2, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIG. 2. In a first step of the method, the host computer 24 provides, such as via processing circuitry 42 and/or communication interface 40 and/or host application 50, user data (Block S100). In an optional substep of the first step, the host computer 24 provides, such as via processing circuitry 42 and/or communication interface 40 and/or host application 50, the user data by executing a host application, such as, for example, the host application 50 (Block S102). In a second step, the host computer 24 initiates a transmission carrying the user data, such as via processing circuitry 42 and/or communication interface 40 and/or host application 50, to the WD 22 (Block S104). In an optional third step, the network node 16 transmits, such as via processing circuitry 68 and/or processor 70 and/or radio interface 62 and/or communication interface 60, to the WD 22 the user data which was carried in the transmission that the host computer 24 initiated, in accordance with the teachings of the embodiments described throughout this disclosure (Block S106). In an optional fourth step, the WD 22 executes a client application, such as, for example, the client application 92, associated with the host application 50 executed by the host computer 24 (Block s 108).

FIG. 4 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 1, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 1 and 2. In a first step of the method, the host computer 24 provides user data, such as via processing circuitry 42 and/or communication interface 40 and/or host application 50, (Block S 110). In an optional substep (not shown) the host computer 24 provides the user data by executing a host application, such as, for example, the host application 50. In a second step, the host computer 24 initiates a transmission carrying the user data, such as via processing circuitry 42 and/or communication interface 40 and/or host application 50, to the WD 22 (Block S 112). The transmission may pass via the network node 16, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step, the WD 22 receives the user data, such as via processing circuitry 84 and/or radio interface 82 and/or client application 92, carried in the transmission (Block SI 14).

FIG. 5 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 1, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 1 and 2. In an optional first step of the method, the WD 22 receives input data, such as via processing circuitry 84 and/or radio interface 82 and/or client application 92, provided by the host computer 24 (Block SI 16). In an optional substep of the first step, the WD 22 executes the client application 92, such as via processing circuitry 84 and/or radio interface 82, which provides the user data in reaction to the received input data provided by the host computer 24 (Block S 118). Additionally or alternatively, in an optional second step, the WD 22 provides user data, such as via processing circuitry 84 and/or radio interface 82 and/or client application 92, (Block S120). In an optional substep of the second step, the WD provides the user data by executing a client application, such as, for example, client application 92 (Block S122). In providing the user data, the executed client application 92 may further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the WD 22 may initiate, such as via processing circuitry 84 and/or radio interface 82 and/or client application 92, in an optional third substep, transmission of the user data to the host computer 24 (Block S124). In a fourth step of the method, the host computer 24 receives the user data, such as via processing circuitry 42 and/or communication interface 40 and/or host application 50, transmitted from the WD 22, in accordance with the teachings of the embodiments described throughout this disclosure (Block S126).

FIG. 6 is a flowchart illustrating an example method implemented in a communication system, such as, for example, the communication system of FIG. 1, in accordance with one embodiment. The communication system may include a host computer 24, a network node 16 and a WD 22, which may be those described with reference to FIGS. 1 and 2. In an optional first step of the method, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 16 receives, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, user data from the WD 22 (Block S128). In an optional second step, the network node 16 initiates transmission, such as via processing circuitry 68 and/or processor 70 and/or radio interface 62 and/or communication interface 60, of the received user data to the host computer 24 (Block S130). In a third step, the host computer 24 receives the user data, such as via processing circuitry 42 and/or communication interface 40 and/or host application 50, carried in the transmission initiated by the network node 16 (Block s 132).

FIG. 7 is a flowchart of an example process in a network node 16 for switching between single layer and multilayer uplink transmission. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 68 (including the ratio determiner 32), processor 70, radio interface 62 and/or communication interface 60. Network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is configured to measure a received signal quality of a scheduled uplink transmission from the WD (Block S134). The network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is further configured to determine a signal quality metric for single layer reception and multilayer reception based on the measured received signal quality (Block S136). The network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is further configured to determine a ratio of signal quality for multilayer reception to a signal quality of single layer reception (Block S138). The network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is further configured to determine a number of layers for a next uplink transmission from the WD based on the determined ratio (Block S140).

FIG. 8 is a flowchart of another example process in a network node 16 for switching between single layer and multilayer uplink transmission. One or more blocks described herein may be performed by one or more elements of network node 16 such as by one or more of processing circuitry 68 (including the ratio determiner 32), processor 70, radio interface 62 and/or communication interface 60. Network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is configured to measure a received signal quality of a scheduled uplink transmission from the WD (Block S142). The network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is further configured to determine a signal quality metric for a single layer reception and a signal quality metric for a multilayer reception based on the measured received signal quality (Block S144). The network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is further configured to determine a relationship at least between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception (Block S146).

The network node 16 such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60 is further configured to determine a number of layers for a next uplink transmission from the WD based on the determined relationship (Block S 148).

In another embodiment, the determined number of layers is one of greater than 1 if the determined relationship is greater than an upper threshold, unchanged if the determined relationship is within the upper threshold and a lower threshold, and equal to 1 if the determined relationship is less than the lower threshold. In some embodiments, the method further includes selecting, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, an uplink precoder from a precoder codebook based on the determined number of layers when the determined number of layers is greater than 1.

In some other embodiments, the method further includes determining, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, a rank hypothesis based at least on the measured received signal quality and determining an ICC estimation based at least on the rank hypothesis without scheduling an uplink transmission. In another embodiment, determining, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the ICC estimation is further based on at least one of a rank of an uplink reception from the WD, an uplink interference estimation, an uplink power control state, an uplink channel quality estimation, and an average signal to noise ratio, SINR.

In some other embodiments, the determination of the relationship between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception is further based at least in part on the determined ICC estimation. In another embodiment, the method further includes determining, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, a modulation and coding scheme, MCS, to be utilized by the WD in the next uplink transmission, the determined MCS being based at least on the determined ICC estimation. In another embodiment, the method further includes causing one of a single layer transmission by the WD and a multilayer transmission by the WD based at least on the determined number of layers.

Having described the general process flow of arrangements of the disclosure and having provided examples of hardware and software arrangements for implementing the processes and functions of the disclosure, the sections below provide details and examples of arrangements for switching between single layer and multilayer uplink transmission.

Consider a multiple input multiple output (MIMO) wireless cellular system having a network node 16 and one or multiple connected WDs 22. Assume that the network node 16 has an iV-element antenna array and that the WD 22 is equipped with an M-element antenna. The WD 22 can transmit multiple independent data streams (layers) to the network node using the MXL wideband precoding matrix W_L where L > 1 is the number of uplink transmission layers. The number of layers L is selected by the network node 16, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, where L £ L_max and L_max < min(M, N) is the maximum number of layers that can be transmitted by the WD 22 in the uplink. Accordingly, the precoding matrix is selected by the network node such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, from a finite codebook 0_L containing all rank L precoders that can be supported by the WD 22. The number of layers and precoding matrix may be signaled by the network node, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, to the WD 22 in the uplink grant to be used in its next uplink transmission. In addition to multi-layer transmission, the WD 22 can transmit, such as via radio interface 82, a single layer using only 1 antenna where all the available uplink transmission power is utilized to transmit from this antenna. In this case, there may be no need to transmit any uplink precoding information leading to reduction in the size of the uplink grant. In certain scenarios, the WD 22 may be communicating, such as via radio interface 82, with more than one network node. In such scenarios, for example, assume that the network nodes 16a and 16b each has an iV-element antenna array and that the WD 22 is equipped with an M-element antenna. The WD 22 can transmit, such as via radio interface 82, multiple independent data streams (layers) to the network node using the MXL wideband precoding matrix W_L where L > 1 is the number of uplink transmission layers. The number of layers L is selected, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, by one of the network nodes 16a or 16b where L < L_max and L_max < min(M, 2 N) is the maximum number of layers that can be transmitted by the WD 22 in the uplink. Accordingly, the precoding matrix is selected by the network node, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, from a finite codebook 0_L containing all rank L precoders that can be supported by the WD 22. In some embodiments, a system and algorithm to switch, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, between single layer and multi-layer uplink transmission are provided. Some embodiments maximize an uplink transmission performance metric, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60. In some embodiments, the ICC of the uplink transmission are considered as the performance metric, i.e., the number of bits that can be correctly decoded with a target block/ bit error rate at the network node 16. Other performance metrics may include the average delay or latency of the uplink transmission and/or the block error rate of the uplink transmission.

FIG. 9 shows a block diagram of an example system for switching between single-layer and multi-layer uplink transmission modes for maximizing the uplink ICC. The example system of FIG. 9 may be implemented by processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, in network node 16. However, it is understood that the elements of FIG. 9 can be implemented in or across other devices and/or multiple network nodes 16. When an uplink scheduling request is received, the processing circuitry 68 may decide, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the transmission mode based on the filtered ICC ratio (Block S150). The instantaneous ICC ratio may be defined at time instant t, n_ICC(t), as the ratio between the maximum ICC of multi-layer transmission and that of a single layer transmission, as follows:

where r_jK(t) is the ICC estimated, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, of a K -layer uplink transmission at time t (Block S158) and (Block S160).

The instantaneous ICC ratio is filtered, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, over time to smooth out variations in the instantaneous ICC ratio (Block S154). When an uplink reception is received at time t, the filtered ICC ratio may be updated, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, using the instantaneous ICC ratio computed at this time instant, for example using a first-order filter, as follows: nice ^{= a} nice + (1 ^{— a}) n_ICC(t) where n_ICC is the filtered ICC ratio and 0 < a < 1 is the filtering parameter that controls the memory of the filter (Block S154).

Alternatively, the average ICC ratio, n_ICC at time t can be computed, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, as ratio of the maximum average ICC of multi-layer transmission to the average ICC of a single layer transmission, as follows: nice

where rj_L = 0rj_L + (1 — q)h _L(t) and rj₁ = Qh₁ + (1 — q)h _t(t), 0 < Q £ 1 is the filtering parameter (Block S154).

In some embodiments, the transmission mode may be selected, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, by comparing the filtered ICC ratio against an upper threshold

and a lower threshold (Block S 150). If the ICC ratio satisfies I1_ICC >

(an upper threshold) then transmission is switched, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, to multi-layer transmission mode, while if I1_ICC

(a lower threshold) then transmission is switched, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, to single layer transmission mode (Block S150). Otherwise, the transmission mode used in the previous uplink transmission is also used in the next uplink transmission. Other mode selection algorithms are also possible that compare the filtered ICC against a single threshold while taking into consideration a lower bound on the time duration of operating in any transmission mode. In this case, switching is allowed only when the a given number of uplink transmissions are scheduled using the current transmission mode.

FIG. 9 shows that when multi-layer transmission mode is selected, the transmission rank, L, is selected such that the selected rank yields the maximum ICC, i.e.,

L = argmax ¾(t)

2< K£L_max

Afterwards, the uplink precoder may be selected, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, from the rank-L precoder codebook 0_L (Block S156). On the other hand, when single-layer transmission is selected, there is no need for precoding. Finally, the estimated uplink ICC is forwarded, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, to the uplink link adaptation algorithm to determine the modulation and coding scheme (MCS) to be used by the WD 22 in the next uplink transmission (Block S158) and/or (Block S162). This information is also signaled, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, to the WD 22 in the uplink grant. Note that for each transmission rank, there may exist a dedicated ICC estimator, (Block S160) and/or (Block S164), that estimates, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the ICC associated with this transmission rank.

Some embodiments of ICC estimation algorithm, (Block S158) and/or (Block S162), and the ICC ratio computation (Block S154) algorithm implemented, for example, by processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, are as follows.

Some embodiments use a separate ICC estimator, (Block S160) and (Block S164), for each possible rank hypothesis L where 1 £ L < L_max. FIG. 10 shows a block diagram of an example ICC computation algorithm associated with rank hypothesis L. As noted above, this algorithm may be implemented, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60. The state of the ICC estimator may be updated when a rank-L uplink transmission is received, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, at time t_L (Block S166). First, the algorithm may compute, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the average estimated SINR at the output of the cell receiver (Block S166) for the L-layer uplink transmission by averaging the estimated output SINR over all the active frequency bands used in the uplink transmission and the transmitted layers, as follows:

where Nf_L(t_L) is the number of frequency bins used in the rank-L transmission that occurred at time instant t_L.

The algorithm also estimates, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the interference-plus-noise (IPN) of the uplink for each frequency bin, /(/, t_L) , e.g., by subtracting the received desired signal power from the total received power at this frequency bin (Block S168). An average IPN estimate / is then obtained by averaging over frequency, as follows:

where Nf(t_L) is the total number of frequency bins over which the IPN is estimated at time instant t_L .

In addition, the average WD 22 transmission power per frequency bin is calculated, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, (Block S170), as:

The uplink channel quality estimator (Block S172) may estimate, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the rank-L uplink channel gain using the estimates of the average SINR, average IPN, and the average WD 22 transmission power per frequency bin as follows:

The channel gain G_L(t_L ) is filtered in the time domain to reduce temporal variations and obtain a stable and accurate measure of the average rank-L uplink channel gain G_L.

Using the average channel gain and uplink IPN, the rank-L gain to interference-plus-noise ratio, G1NR_L(/, t_L) may be calculated, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, for each frequency bin, (Block S172), as follows:

which is then used by the ICC estimator, (Block S 174), to calculate, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the rank-L SINR for each frequency band as follows:

SINR _L(f, t_L) = p(f, t_L) G1NR_l(/, t_L) The total ICC for rank-L transmission can then be calculated, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, by mapping the SINR for each frequency bin to the corresponding information capacity for the target block error rate. For example, using the Shannon capacity formula for an additive white Gaussian channel and error-free reception, the total ICC estimate at time t_L is given by:

According some embodiments, the L transmission layers may be received, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, across multiple network nodes when the WD is simultaneously connected to multiple network nodes. For example, LI and L2 layers may be respectively received by network nodes 16a and 16b. In such scenarios, the SINR is independently for LI and L2 layers and then total ICC is estimated summing the ICC as follows. J?_L(t_L) = V log (1 + SINR_L1( , t_L)) + ^ log (l + SINR _i2(/, t_L))

/ /

In this scenario, a single layer transmission can be received by network 16a or

16b.

FIG. 11 shows a block diagram of an example ICC ratio computation algorithm, as may be performed by processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60. In some embodiments, the instantaneous ICC ratio may be computed by the network node 16, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, from each uplink reception. When a rank-L uplink transmission is received at time t_L, the ICC estimate of rank-L transmission,

I^S readily available using the ICC estimator associated with rank-L hypothesis described above, (Block S176). In order to compute, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, the instantaneous ICC ratio, (Block S180), at time t_L, an estimate ICC of the remaining rank hypotheses may be used (Block S 178). In other words: ¾(ti) for 1 < K £ L_max and K ¹ L.

In some embodiments, the ICC of the remaining rank hypotheses, (Block S178), can be estimated, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, as that obtained from the corresponding ICC estimator, (Block S176), at its latest update time instant as follows:

VK( L) ⁼ VK( K) where t_K is the time instant at which the latest K — layer uplink transmission was received. In some embodiments, the ICC of the remaining rank hypotheses can be estimated, (Block S178), such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, using the information available from the uplink channel quality estimator associated with the rank-L ICC estimator. In order to compute the ICC estimate for rank K hypothesis, utilize the rank-L signal to interference-plus-noise ratio,

SINR_l(/, t_L) to estimate SINR^ (/, t_L) as follows:

where p_K is the average power used to transmit one layer of a rank- K uplink transmission and b_k is a penalty term that corresponds to the residual inter-layer interference at the output of the cell receiver in decibel. For example, for a network node 16 equipped with a 64-antenna interference rejection receiver, the values of b_k can be selected as 0, 0.5, 1, and 2 dB for K = 1, 2, 3, and 4, respectively. After calculating SINR^ (/, t_L) for different frequencies /, the total ICC for rank-/6 transmission can then be calculated, such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, by mapping the SINR for each frequency bin to the corresponding information capacity for the target block error rate. This can be done using the Shannon capacity formula for an additive white Gaussian channel and error-free reception. The total ICC estimate at time t_L may be given by:

After computing the instantaneous ICC ratio, the network node may update, (Block S182), such as via processing circuitry 68 and/or ratio determiner 32 and/or processor 70 and/or radio interface 62 and/or communication interface 60, a filtered ICC ratio based at least on the instantaneous ICC ratio computed, (Block SI 80) to determine a filtered ICC ratio.

The performance of the proposed uplink SU-MIMO precoding technique using system-level simulations has been evaluated by simulating 5G cellular system with bandwidth 30 MHz and carrier frequency 3.5 GHz. The simulated system operates in time division duplex mode where the downlink/uplink timeslot pattern is 3/1. Consider a 7-site deployment scenario where each site has 3 cells, the inter-site distance is equal to 1.7 Km and the WDs 22 are dropped randomly in the simulation area. The simulation assumes that all the WDs 22 have non-coherent uplink transmission capabilities and that the number of uplink transmission antennas is equal to 2. Hence, the maximum number of uplink layers is given by 2. In addition, consider a single layer uplink transmission with full transmission power from antenna port 0.

The parameters of the proposed mode selection algorithm are selected as

= 1.1, = 0.9, and a = 0.95. The 5G spatial channel model (SCM) Urban Macro channel model with non-line of sight (NLOS) communication is used in this simulation. The antenna configuration at the network node 16 is the advanced antenna system (AAS) AIR 6488 (4x8x2) configuration and the traffic model for the uplink is selected as full buffer. Simulation results are averaged over 10 Monte Carlo runs where in each run the WDs 22 are dropped in independent random locations and the simulation duration is selected as 10 seconds. The performance of the proposed algorithm is compared with the performance of the multi-layer uplink transmission scheme where the transmission rank is adaptively selected between 1 and 2, and the single-layer transmission scheme where full power is always utilized to transmit 1- layer from the first antenna of the WD 22.

FIG. 12 shows the average uplink cell throughput over the 21 cells versus the number of WDs 22 in the simulation area. This figure shows that the proposed algorithm yields a performance slightly better than known multi-layer transmission algorithms. Furthermore, the gain due to multi-layer uplink transmission using the proposed algorithm is around 45% compared to fixed rank 1-layer transmission. This is due to the ability of the proposed algorithm to increase the number of layers for the WDs 22 that are in good radio conditions, e.g., the WDs 22 that are located close to their serving network node. FIG. 13 shows the average uplink cell edge throughput, i.e., the average 10^th percentile of the uplink throughput of each WD 22, versus the number of WDs 22 in the simulation area. As can be seen, the cell edge throughput of the proposed algorithm is very close to that of the single layer transmission. This confirms the ability of the proposed algorithm to adaptively select the transmission rank based on the channel conditions where the algorithm selects transmission rank 1 for WDs 22 at the cell edge yielding similar cell edge throughout to that obtained via single layer transmission.

FIG. 14 shows the average number of uplink layers versus the number of active WDs 22 in the system. This figure that the proposed switching algorithm yields an average number of layers close to 1.5. On the other hand, some known multi-layer transmission algorithms selects a larger number of layers on average for all WDs 22 that is very close to 2 layers and does not consider the performance of cell edge WDs 22. FIG. 15 shows the average number of switching events between single layer and multi-layer transmission. As can be seen, using the proposed switching algorithm does not cause excessive switching events as using the two switching thresholds

and ijcc prevents the algorithm from going into hysteresis. This may be particularly important in cellular systems where switching the transmission mode of the WD 22 may require higher-layer messages that incur additional delay and performance loss Thus, some embodiments may include at least one of the following: A network node 16 for switching the uplink transmission mode between single layer and multi-layer transmission for maximizing a signal quality metric;

A method at the network node 16 to adaptively switch between single layer and multilayer transmission comprising; measuring a received signal quality of a scheduled UL transmission; computing a signal quality metric for single layer reception and multilayer reception based on the measured received signal quality; computing a ratio of maximum signal quality metric for multilayer reception to the signal quality of a single layer reception; and determining layers for the next UL transmission based on the computed ratio; and

A method at the network node 16 for estimating the ICC ratio using only the ICC estimate obtained from processing the current uplink transmission without the need for scheduling any uplink transmissions for the purpose of updating the statistics corresponding to different rank hypotheses.

According to one aspect, a network node 16 configured to communicate with a WD 22 is provided. The network node 16 includes a radio interface 62 and/or comprising processing circuitry 68 configured to: measure a received signal quality of a scheduled uplink transmission from the WD 22, determine a signal quality metric for single layer reception and multilayer reception based on the measured received signal quality, determine a ratio of a signal quality for multilayer reception to a signal quality of single layer reception, and determine a number of layers for a next uplink transmission from the WD 22 based on the determined ratio.

According to this aspect, in some embodiments, the ratio is obtained using only an information carrying capacity (ICC) estimate obtained from processing a current uplink transmission without the need for scheduling any uplink transmission for updating statistics corresponding to different rank hypothesis. In some embodiments, the network node 16, radio interface 62 and/or processing circuitry 68 is further configured to switch the uplink transmission mode between single layer and multi-layer transmission for increasing a signal quality metric above a level of the determined signal quality. In some embodiments, the network node 16, radio interface 62 and/or processing circuitry 68 is further configured to determine the ratio for each of a plurality of rank hypotheses and a receiving network node 16. In some embodiments, a rank hypothesis is updated when a rank uplink transmission is received from the WD 22. In some embodiments, the measure of a received signal quality of a scheduled uplink transmission from the WD 22 comprises combining measured signal qualities from received signals from WDs 22 at other network nodes. In some embodiments, the network node 16, radio interface 62 and/or processing circuitry 68 is further configured to switch an uplink transmission mode between single layer towards the network node, another network node and/or a WD 22 and multi-layer transmission for increasing a signal quality metric above a level of the determined signal quality. According to another aspect, a method including steps that may be performed by processing circuitry 68. The method includes measuring a received signal quality of a scheduled uplink transmission from the WD 22, determining a signal quality metric for single layer reception and multilayer reception based on the measured received signal quality, determining a ratio of a signal quality for multilayer reception to a signal quality of single layer reception, and determining a number of layers for a next uplink transmission from the WD 22 based on the determined ratio.

According to this aspect, in some embodiments, the ratio is obtained, via the ratio determiner 32, using only an information carrying capacity (ICC) estimate obtained from processing a current uplink transmission without the need for scheduling any uplink transmission for updating statistics corresponding to different rank hypothesis. In some embodiments, the method further includes switching the uplink transmission mode between single layer and multi-layer transmission for increasing a signal quality metric above a level of the determined signal quality. In some embodiments, the method further includes determining the ratio for each of a plurality of rank hypotheses and receiving network nodes 16. In some embodiments, a rank hypothesis is updated when a rank uplink transmission is received from the WD 22. In some embodiments, the measure of a received signal quality of a scheduled uplink transmission from the WD 22 comprises combining measured signal qualities from received signals from WD 22 at other network nodes. In some embodiments, the method further includes an uplink transmission mode between single layer towards the network node, another network node and/or a WD 22 and multi-layer transmission for increasing a signal quality metric above a level of the determined signal quality The foregoing paragraphs describe example embodiments that implement techniques for switching between single layer and multilayer uplink transmission. However, it will be appreciated that directly analogous methods may also be implemented for switching between single layer and multilayer downlink transmission. For example, from the UL transmissions from the WD 22, received at the network node(s) 16, the channel covariance matrix may be computed.

Subsequently, following procedures presented herein, the number of DL transmission layers from the network node(s) 16 can be determined. IPN may be estimated from the DL channel quality feedback from the WD 22.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, computer program product and/or computer storage media storing an executable computer program. Accordingly, the concepts described herein may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects all generally referred to herein as a “circuit” or “module.” Any process, step, action and/or functionality described herein may be performed by, and/or associated to, a corresponding module, which may be implemented in software and/or firmware and/or hardware. Furthermore, the disclosure may take the form of a computer program product on a tangible computer usable storage medium having computer program code embodied in the medium that can be executed by a computer. Any suitable tangible computer readable medium may be utilized including hard disks, CD-ROMs, electronic storage devices, optical storage devices, or magnetic storage devices.

Some embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, systems and computer program products. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer (to thereby create a special purpose computer), special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer program instructions may also be stored in a computer readable memory or storage medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instruction means which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks.

It is to be understood that the functions/acts noted in the blocks may occur out of the order noted in the operational illustrations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows. Computer program code for carrying out operations of the concepts described herein may be written in an object oriented programming language such as Java® or C++. However, the computer program code for carrying out operations of the disclosure may also be written in conventional procedural programming languages, such as the "C" programming language. The program code may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer. In the latter scenario, the remote computer may be connected to the user's computer through a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider).

Many different embodiments have been disclosed herein, in connection with the above description and the drawings. It will be understood that it would be unduly repetitious and obfuscating to literally describe and illustrate every combination and subcombination of these embodiments. Accordingly, all embodiments can be combined in any way and/or combination, and the present specification, including the drawings, shall be construed to constitute a complete written description of all combinations and subcombinations of the embodiments described herein, and of the manner and process of making and using them, and shall support claims to any such combination or subcombination. It will be appreciated by persons skilled in the art that the embodiments described herein are not limited to what has been particularly shown and described herein above. In addition, unless mention was made above to the contrary, it should be noted that all of the accompanying drawings are not to scale. A variety of modifications and variations are possible in light of the above teachings without departing from the scope of the following claims.

Claims

What is claimed is:

1. A network node (16) configured to communicate with a wireless device (22), WD, the network node (16) comprising: processing circuitry (68), the processing circuitry (68) being configured to: measure a received signal quality of a scheduled uplink transmission from the WD (22); determine a signal quality metric for a single layer reception and a signal quality metric for a multilayer reception based on the measured received signal quality; determine a relationship at least between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception; and determine a number of layers for a next uplink transmission from the WD (22) based on the determined relationship.

2. The network node (16) of Claim 1, wherein the relationship is a ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception, the signal quality metric for the multilayer reception being based at least on uplink information carrying capacity, ICC, for the multilayer reception, and the signal quality metric for the single layer reception being based at least on uplink ICC for the single layer reception.

3. The network node (16) of Claim 2, wherein the determined number of layers for the next uplink transmission maximizes the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception.

4. The network node (16) of Claim 2, wherein the determined number of layers for the next uplink transmission is selected based at least on the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception.

5. The network node (16) of any one of Claims 1-4, wherein the determined number of layers is one of: greater than 1 if the determined relationship is greater than an upper threshold; unchanged if the determined relationship is within the upper threshold and a lower threshold; and equal to 1 if the determined relationship is less than the lower threshold.

6. The network node (16) of any one of Claims 1-5, wherein the processing circuitry (68) is further configured to: select an uplink precoder from a precoder codebook based on the determined number of layers when the determined number of layers is greater than 1.

7. The network node (16) of any one of Claims 1-6, wherein the processing circuitry (68) is further configured to: determine a rank hypothesis based at least on the measured received signal quality; and determine an ICC estimation based at least on the rank hypothesis without scheduling an uplink transmission.

8. The network node (16) of Claim 7, wherein determining the ICC estimation is further based on at least one of: a rank of an uplink reception from the WD (22); an uplink interference estimation; an uplink power control state; an uplink channel quality estimation; and an average signal to noise ratio, SINR.

9. The network node (16) of any one of Claims 7 and 8, wherein the determination of the relationship between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception is further based at least in part on the determined ICC estimation.

10. The network node (16) of any one of Claims 7-9, wherein the processing circuitry (68) is further configured to: determine a modulation and coding scheme, MCS, to be utilized by the WD (22) in the next uplink transmission, the determined MCS being based at least on the determined ICC estimation.

11. The network node (16) of any one of Claims 1-10, wherein the processing circuitry (68) is further configured to: cause one of a single layer transmission by the WD (22) and a multilayer transmission by the WD (22) based at least on the determined number of layers.

12. A method for a network node (16) to determine a transmission mode for communication with a wireless device (22), WD, the method comprising: measuring (S142) a received signal quality of a scheduled uplink transmission from the WD (22); determining (S144) a signal quality metric for a single layer reception and a signal quality metric for a multilayer reception based on the measured received signal quality; determining (S146) a relationship at least between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception; and determining (S148) a number of layers for a next uplink transmission from the WD (22) based on the determined relationship.

13. The method of Claim 12, wherein the relationship is a ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception, the signal quality metric for the multilayer reception being based at least on uplink information carrying capacity, ICC, for the multilayer reception, and the signal quality metric for the single layer reception being based at least on uplink ICC for the single layer reception.

14. The method of Claim 13, wherein the determined number of layers for the next uplink transmission maximizes the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception.

15. The method of Claim 13, wherein the determined number of layers for the next uplink transmission is based at least on the ratio of the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception.

16. The method of any one of Claims 12-15, wherein the determined number of layers is one of: greater than 1 if the determined relationship is greater than an upper threshold; unchanged if the determined relationship is within the upper threshold and a lower threshold; and equal to 1 if the determined relationship is less than the lower threshold.

17. The method of any one of Claims 12-16, further including: selecting an uplink precoder from a precoder codebook based on the determined number of layers when the determined number of layers is greater than 1.

18. The method of any one of Claims 12-17, further including: determining a rank hypothesis based at least on the measured received signal quality; and determining an ICC estimation based at least on the rank hypothesis without scheduling an uplink transmission.

19. The method of Claim 18, wherein determining the ICC estimation is further based on at least one of: a rank of an uplink reception from the WD (22); an uplink interference estimation; an uplink power control state; an uplink channel quality estimation; and an average signal to noise ratio, SINR.

20. The method of any one of Claims 18 and 19, wherein the determination of the relationship between the signal quality metric for the multilayer reception and the signal quality metric of the single layer reception is further based at least in part on the determined ICC estimation.

21. The method of any one of Claims 18-20, further including: determining a modulation and coding scheme, MCS, to be utilized by the WD

(22) in the next uplink transmission, the determined MCS being based at least on the determined ICC estimation.

22. The method of any one of Claims 12-21, further including: causing one of a single layer transmission by the WD (22) and a multilayer transmission by the WD (22) based at least on the determined number of layers.

23. A computer storage medium (72) storing an executable computer program that, when executed by processing circuitry (68) causes the processing circuitry (68) to at least one of perform and control a method according to any one of Claims 12-22.