WO2019160484A1 - Apparatus and method for reliable decoding of physical downlink control channel - Google Patents

Abstract

An apparatus and method are disclosed for decoding downlink control. In one embodiment, a method in a wireless device (WD) includes, based on decoding a physical control format indicator channel, PCFICH, determining whether the PCFICH is correctly decoded; and in response to determining that the PCFICH is not correctly decoded, performing blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH.

Description

APPARATUS AND METHOD FOR RELIABLE DECODING OF PHYSICAL DOWNLINK CONTROL CHANNEL

TECHNICAL FIELD

Wireless communication and in particular, to wireless device processing when blindly decoding downlink control.

BACKGROUND

Long Term Evolution (LTE) uses orthogonal frequency division multiplexing (OFDM) in the downlink and discrete Fourier transform (DFT)-spread OFDM in the uplink. In the time domain, LTE downlink transmissions are organized into radio frames of 10 milliseconds (ms), each radio frame consisting of ten equally-sized subframes of length Tsubframe = 1 ms, as shown in FIG. 1.

Furthermore, the resource allocation in LTE is typically described in terms of resource blocks (RB), where a resource block corresponds to one slot (0.5 ms) in the time domain and 12 contiguous subcarriers in the frequency domain. A pair of two adjacent resource blocks in the time direction (1.0 ms) is known as a resource block pair. This is also denoted as TTI (Transmission Time Index).

Downlink transmissions are dynamically scheduled, i.e., in each subframe the base station transmits control information about to which terminals data is transmitted and upon which resource blocks the data is transmitted, in the current downlink subframe. This control signaling is typically transmitted in the first 1, 2, 3 or 4 OFDM symbols in each subframe and the number n=l,2,3 or 4 is known as the Control Format Indicator (CFI) indicated by the physical CFI channel (PCFICH) transmitted in the first symbol of the control region. The control region also contains physical downlink control channels (PDCCH) and possibly also physical hybrid automatic repeat request (HARQ) indication channels (PHICH) carrying acknowledgment/non acknowledgement (ACK/NACK) for the uplink transmission.

The downlink subframe also contains common reference symbols (CRS), which are known to the receiver and used for coherent demodulation of e.g. the control information. A downlink system with CFI=3 OFDM symbols as control is illustrated in FIG. 2. In a 3^rd Generation Partnership Project (3GPP) Release-8 TTI, one such portion of the DL transmission is termed as one TTI. Receiving the (short) physical downlink control channel, (S)PDCCH, is dependent on the reception of the Physical Control Format Indicator Channel, PCFICH.

The PCFICH is carries information on the number of PDCCH symbols used in the LTE subframe, also called Control Format Indicator, CFI. The CFI can take the value of 1, 2 or 3, indicating that the PDCCH is mapped onto 1, 2 or 3 symbols.

The wireless device (WD) may search for a valid PDCCH once the WD knows the size of the PDCCH region.

It may know possible mappings of PDCCH candidates in the search and hence the search is limited to a certain set of mapping combinations, also called a search space. The mapping of a given PDCCH candidate to physical resources is dependent on the CFI. That is, the WD may know the CFI in order to know how the PDCCH candidates are mapped.

The PDCCH can be transmitted using one of several available aggregation levels (ALs). An aggregation level, also called a PDCCH format, is an aggregation of resources for transmitting the information. For example, if comparing aggregation level N with a higher aggregation level M, M/N more resources are used in AL M compared to AL N. The aggregation levels are currently defined in levels of 2ⁿ, where n={0,l,2,3}.

The more resources that are used for transmitting the PDCCH the better is the receiver performance. If ignoring aspects such as difference in diversity and channel estimation performance, a doubling of the aggregation level results in a 3 dB gain on link level in a noise limited environment. Since the PDCCH decoding relies on the PCFICH decoding, the PCFICH should be more reliable than PDCCH. However, PCFICH may not be configured with the concept of aggregation levels (unlike

PDCCH), but has been designed for a“worst case” coverage scenario and is not adapted based on the WD coverage since the PCFICH is broadcasted to all WDs, which may not be efficient, as discussed in more detail below.

SUMMARY Some embodiments advantageously provide methods and wireless devices for reducing wireless device processing (as compared with known arrangements) when blindly decoding downlink control.

In some embodiments, the WD will analyze the PCFICH decoding and, based on the outcome, execute blind decoding in different ways depending on whether the PCFICH is considered to have been correctly decoded.

According to one aspect, a wireless device WD is configured to communicate with a network node and has processing circuitry configured to determine if a physical control format indicator channel, PCFICH, is correctly decoded. If the PCFICH is correctly decoded, then a search for a valid physical downlink control channel, PDCCH, candidate is performed assuming a number of symbols of the PDCCH channel indicated by a control format indicator, CFI, of the PCFICH. If the PCFICH is determined not to be correctly decoded, then blind decoding of the PDCCH is performed only for a subset of possible aggregation levels. In some embodiments, if the PCFICH is determined not to be correctly decoded, then the blind decoding of the PDCCH is performed only for a subset of possible aggregation levels where performance is considered limited by PCFICH decoding.

According to one aspect of the disclosure, a wireless device, WD, configured to communicate with a network node is provided. The WD comprises processing circuitry configured to, based on decoding a physical control format indicator channel, PCFICH, determine whether the PCFICH is correctly decoded; and in response to determining that the PCFICH is not correctly decoded, perform blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH.

In some embodiments of this aspect, the processing circuitry is further configured to, in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH for a subset of possible aggregation levels of the at least one CFI. In some embodiments of this aspect, the processing circuitry is further configured to, in response to determining that the PCFICH is correctly decoded, perform a search for a PDCCH candidate assuming a number of symbols of the PDCCH indicated by the CFI of the PCFICH; and in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH assuming a number of symbols of the PDCCH indicated by the assumed at least one CFI. In some embodiments of this aspect, the processing circuitry is further configured to determine the assumed at least one CFI from a table. In some embodiments of this aspect, the subset of possible aggregation levels correspond to aggregation levels where performance is determined to be limited by the PCFICH decoding.

In some embodiments of this aspect, the assumed at least one CFI is based at least in part on at least one decoding metric. In some embodiments of this aspect, an order of which the assumed at least one CFI is attempted is further based at least in part on at least one of a cell bandwidth and a traffic type. In some embodiments of this aspect, the processing circuitry is further configured to perform the blind decoding of the PDCCH by being configured to perform successive blind decoding attempts assuming a different CFI of the at least one CFI for each successive blind decoding attempt. In some embodiments of this aspect, the processing circuitry is further configured to, in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH only for a subset of possible aggregation levels, the subset of possible aggregation levels corresponding to the aggregation levels in which performance is determined to be limited by the PCFICH decoding.

According to another aspect of the disclosure, a method for a wireless device, WD, is provided. The method comprises, based on decoding a physical control format indicator channel, PCFICH, determining whether the PCFICH is correctly decoded. The method comprises, in response to determining that the PCFICH is not correctly decoded, performing blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH.

In some embodiments of this aspect, the method further includes, in response to determining that the PCFICH is not correctly decoded, performing the blind decoding of the PDCCH for a subset of possible aggregation levels of the at least one CFI. In some embodiments of this aspect, the method further includes, in response to determining that the PCFICH is correctly decoded, performing a search for a PDCCH candidate assuming a number of symbols of the PDCCH indicated by the CFI of the PCFICH; and in response to determining that the PCFICH is not correctly decoded, performing the blind decoding of the PDCCH assuming a number of symbols of the PDCCH indicated by the assumed at least one CFI. In some embodiments of this aspect, the method further includes determining the assumed at least one CFI from a table. In some embodiments of this aspect, the subset of possible aggregation levels correspond to aggregation levels where performance is determined to be limited by the PCFICH decoding.

In some embodiments of this aspect, the assumed at least one CFI is based at least in part on at least one decoding metric. In some embodiments of this aspect, an order of which the assumed at least one CFI is attempted is further based at least in part on at least one of a cell bandwidth and a traffic type. In some embodiments of this aspect, the performing the blind decoding of the PDCCH further comprises performing successive blind decoding attempts assuming a different CFI of the at least one CFI for each successive blind decoding attempt. In some embodiments of this aspect, the method further includes, in response to determining that the PCFICH is not correctly decoded, performing the blind decoding of the PDCCH only for a subset of possible aggregation levels, the subset of possible aggregation levels corresponding to the aggregation levels in which performance is determined to be limited by the PCFICH decoding.

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 an illustration of a frame structure;

FIG. 2 is an illustration of a control signaling and reference symbols in a subframe;

FIG. 3 is a graph of performance curves that show PCFICH and PDCCH performance at different aggregation levels; FIG. 4 is a schematic diagram of an exemplary network architecture illustrating a communication system connected via an intermediate network to a host computer according to the principles in the present disclosure;

FIG. 5 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. 6 is a block diagram of an alternative embodiment of a host computer according to some embodiments of the present disclosure;

FIG. 7 is a block diagram of an alternative embodiment of a network node according to some embodiments of the present disclosure;

FIG. 8 is a block diagram of an alternative embodiment of a wireless device according to some embodiments of the present disclosure;

FIG. 9 is a flowchart illustrating exemplary 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. 10 is a flowchart illustrating exemplary 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. 11 is a flowchart illustrating exemplary 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. 12 is a flowchart illustrating exemplary 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. 13 is a flowchart of an exemplary process in a wireless device according to some embodiments of the present disclosure;

FIG. 14 is a flowchart of an exemplary process in a wireless device configured to analyze the PCFICH decoding and, based on the outcome, execute blind decoding in different ways depending on whether the PCFICH is considered to be correctly decoded; and

FIG. 15 is a diagram of subslots for transmission of SPDCCH.

DETAILED DESCRIPTION

As discussed above, since the PDCCH decoding relies on the PCFICH decoding, the PCFICH should be more reliable than PDCCH. However, PCFICH may not be configured with the concept of aggregation levels (unlike PDCCH), but has been designed for a“worst case” coverage scenario and is not adapted based on the WD coverage since the PCFICH is broadcasted to all WDs, which may not be efficient.

If, however, the aggregation level is further increased compared to the aggregation level defined when PCFICH was designed, the PCFICH performance might become the bottleneck. One measure to prevent this is to also aggregate the PCFICH, but this might have issues with backwards compatibility in the network.

FIG. 3 shows example PCFICH and PDCCH performance at different aggregation levels. Three types of performance curves are shown:

1. Isolated PCFICH performance

2. Isolated PDCCH performance

3. PDCCH performance that is dependent on a correct PCFICH decoding

As can be seen in FIG. 3, when the aggregation level increases, the PCFICH limits the PDCCH performance (for a given aggregation level, the dashed line will be to the right of the solid line).

Thus, in some embodiments of the present disclosure, the WD is configured to analyze the PCFICH decoding and, based on the outcome, execute blind decoding in different ways depending on whether the PCFICH is considered to have been correctly decoded.

Before describing in detail exemplary embodiments, it is noted that the embodiments reside primarily in combinations of apparatus components and processing steps related to reducing wireless device processing when blindly decoding downlink control. 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), 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 a 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), relay node, integrated access and backhaul (LAB) 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, 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.

As used herein, a“valid PDCCH” is a downlink (DL) control that is scheduled for the WD. This means that the identity the WD searches for matches the decoding of the PDCCH. In some cases, the ID is exclusively-ORed with the cyclic redundancy check (CRC) bits for determining a match.

Embodiments provide for wireless device processing when blindly decoding downlink control in a manner that is a reduction over the processing used in known arrangements. Some embodiments allow the network to increase the aggregation level of the PDCCH to improve downlink (DL) control performance in the wireless communication system while leaving the PCFICH untouched to ensure backwards compatibility in the system. According to one aspect, a wireless device WD may be configured to communicate with a network node and has processing circuitry configured to determine if a physical control format indicator channel, PCFICH, is correctly decoded. If the PCFICH is correctly decoded, then the processing circuitry is configured to search for a valid physical downlink control channel, PDCCH, assuming a size of the PDCCH channel indicated by a control format indicator, CFI, of the PCFICH. If the PCFICH is not correctly decoded, then the processing circuitry is further configured to perform blind decoding of the PDCCH only for aggregation levels (ALs) where performance is considered limited by PCFICH decoding. For example, ALs where performance is considered limited by the PCFICH decoding may include, for example, aggregation levels whose performances are determined to be better than those of PCFICH for e.g., a given signal -to-noise ratio (SNR).

Returning to the drawing figures, in which like elements are referred to by like reference numerals, there is shown in FIG. 4 a schematic diagram of a communication system, according to an embodiment, including a communication system 10, such as a 3GPP-type cellular network, 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 l6a, l6b, l6c (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 l8a, 18b, l8c (referred to collectively as coverage areas 18). Each network node l6a, l6b, l6c is connectable to the core network 14 over a wired or wireless connection 20. A first wireless device (WD) 22a located in coverage area l8a is configured to wirelessly connect to, or be paged by, the corresponding network node l6c. A second WD 22b in coverage area 18b is wirelessly connectable to the corresponding network node l6a. 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.

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. 4 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 wireless device 22 is configured to include a PDCCH decode unit 34 which is configured to, based on decoding a physical control format indicator channel, PCFICH, determine whether the PCFICH is correctly decoded. The PDCCH decode unit 34 is configured to, in response to determining that the PCFICH is not correctly decoded, perform blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH.

In some embodiments, the WD 22 is configured to include a PDCCH decode unit 42 which is configured to blindly decode a PDCCH when a physical control format indicator, PCFICH, is not correctly decoded, the blind decoding being performed only for aggregation levels where performance is considered limited by PCFICH decoding.

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. 5. 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 a traditional processor 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 comprising 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 a traditional processor 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) 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.

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 a traditional processor 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) 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. For example, the processing circuitry 84 of the wireless device 22 may include a PDCCH decode unit 34 configured to, based on decoding a physical control format indicator channel, PCFICH, determine whether the PCFICH is correctly decoded; and, in response to determining that the PCFICH is not correctly decoded, perform blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH.

In some embodiments, the processing circuitry 84 is further configured to, in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH for a subset of possible aggregation levels of the at least one CFI. In some embodiments, the processing circuitry 84 is further configured to, in response to determining that the PCFICH is correctly decoded, perform a search for a PDCCH candidate assuming a number of symbols of the PDCCH indicated by the CFI of the PCFICH; and, in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH assuming a number of symbols of the PDCCH indicated by the assumed at least one CFI. In some embodiments, the processing circuitry 84 is further configured to determine the assumed at least one CFI from a table. In some embodiments, the subset of possible aggregation levels correspond to aggregation levels where performance is determined to be limited by the PCFICH decoding.

In some embodiments, the assumed at least one CFI is based at least in part on at least one decoding metric. In some embodiments, an order of which the assumed at least one CFI is attempted is further based at least in part on at least one of a cell bandwidth and a traffic type. In some embodiments, the processing circuitry 84 is further configured to perform the blind decoding of the PDCCH by being configured to perform successive blind decoding attempts assuming a different CFI of the at least one CFI for each successive blind decoding attempt. In some embodiments, the processing circuitry 84 is further configured to, in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH only for a subset of possible aggregation levels, the subset of possible aggregation levels corresponding to the aggregation levels in which performance is determined to be limited by the PCFICH decoding.

In some embodiments, the PDCCH decode unit 34 is configured to blindly decode a PDCCH when a physical control format indicator, PCFICH, is not correctly decoded, the blind decoding being performed only for aggregation levels where performance is considered limited by PCFICH decoding.

In some embodiments, the inner workings of the network node 16, WD 22, and host computer 24 may be as shown in FIG. 5 and independently, the surrounding network topology may be that of FIG. 4.

In FIG. 5, 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. 4 and 5 show various “units” such as PDCCH decode unit 34 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. 6 is a block diagram of an alternative host computer 24, which may be implemented at least in part by software modules containing software executable by a processor to perform the functions described herein. The host computer 24 include a communication interface module 41 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 memory module 47 is configured to store data, programmatic software code and/or other information described herein.

FIG. 7 is a block diagram of an alternative network node 16, which may be implemented at least in part by software modules containing software executable by a processor to perform the functions described herein. The network node 16 includes a radio interface module 63 configured 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 network node 16 also includes a communication interface module 61 configured for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 10. The communication interface module 61 may also be configured to facilitate a connection 66 to the host computer 24. The memory module 73 that is configured to store data, programmatic software code and/or other information described herein.

FIG. 8 is a block diagram of an alternative wireless device 22, which may be implemented at least in part by software modules containing software executable by a processor to perform the functions described herein. The WD 22 includes a radio interface module 83 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 memory module 89 is configured to store data, programmatic software code and/or other information described herein. The PDCCH decode module 35 is configured to blindly decode a PDCCH when a physical control format indicator, PCFICH, is not correctly decoded, the blind decoding being performed only for aggregation levels where performance is considered limited by PCFICH decoding.

FIG. 9 is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of FIGS. 4 and 5, 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. 5. In a first step of the method, the host computer 24 provides user data (block S100). In an optional substep of the first step, the host computer 24 provides the user data by executing a host application, such as, for example, the host application 74 (block S102). In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (block S104). In an optional third step, the network node 16 transmits to the WD 22 the user data which was carried in the transmission that the host computer 22 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 114, associated with the host application 74 executed by the host computer 24 (block S108). FIG. 10 is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of FIG. 4, 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. 4 and 5. In a first step of the method, the host computer 24 provides user data (block Sl 10). 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 74. In a second step, the host computer 24 initiates a transmission carrying the user data to the WD 22 (block Sl 12). 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 carried in the transmission (block Sl 14).

FIG. 11 is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of FIG. 4, 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. 4 and 5. In an optional first step of the method, the WD 22 receives input data provided by the host computer 24 (block Sl 16). In an optional substep of the first step, the WD 22 executes the client application 114, which provides the user data in reaction to the received input data provided by the host computer 24 (block Sl 18). Additionally or alternatively, in an optional second step, the WD 22 provides user data (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 114 (block S122). In providing the user data, the executed client application 114 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, 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 transmitted from the WD 22, in accordance with the teachings of the embodiments described throughout this disclosure (block S126).

FIG. 12 is a flowchart illustrating an exemplary method implemented in a communication system, such as, for example, the communication system of FIG. 4, 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. 4 and 5. 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 user data from the WD 22 (block S128). In an optional second step, the network node 16 initiates transmission of the received user data to the host computer 24 (block S 130). In a third step, the host computer 24 receives the user data carried in the transmission initiated by the network node 16 (block S132).

Embodiments provide for reducing the number of blind decodes that the WD 22 performs, compared to not relying on the PCFICH at all. That is, in order for the PCFICH not to be limiting performance, the receiver would have to ignore PCFICH and blindly decode the PDCCH assuming CFI=l,2 or 3. This would triple the blind decodes at the WD 22. As used herein, blind decoding is a decoding attempt of a PDCCH of a given payload size and aggregation level. An aggregation level defines the amount of physical resources a PDCCH candidate for decoding is mapped to. A blind decode is a decoding attempt assuming a control payload size and size of the mapping to physical resources. By adopting the solution described herein, the number of blind decodes may be reduced without degrading overall PDCCH performance.

FIG. 13 is a flowchart of an exemplary process according to some

embodiments of the present disclosure, which may reduce wireless device 22 processing e.g., when blindly decoding downlink control. One or more Blocks and/or functions and/or methods performed by WD 22 may be performed by one or more elements of WD 22 such as by PDCCH decode unit 34 in processing circuitry 84, processor 86, radio interface 82, etc., according to the example method. In some embodiments, the method includes, based on decoding a physical control format indicator channel, PCFICH, determining (block S134), such as via processing circuitry 84 and/or PDCCH decode unit 34, whether the PCFICH is correctly decoded. The method includes, in response to determining that the PCFICH is not correctly decoded, performing (block S136), such as via processing circuitry 84 and/or PDCCH decode unit 34, blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH. In some embodiments, the method includes, in response to determining that the PCFICH is not correctly decoded, performing, such as via processing circuitry 84 and/or PDCCH decode unit 34, the blind decoding of the PDCCH for a subset of possible aggregation levels of the at least one CFI. In some embodiments, the method further includes, in response to determining that the PCFICH is correctly decoded, performing, such as via processing circuitry 84 and/or PDCCH decode unit 34, a search for a PDCCH candidate assuming a number of symbols of the PDCCH indicated by the CFI of the PCFICH. In some embodiments, the method includes, in response to determining that the PCFICH is not correctly decoded, performing, such as via processing circuitry 84 and/or PDCCH decode unit 34, the blind decoding of the PDCCH assuming a number of symbols of the PDCCH indicated by the assumed at least one CFI. In some embodiments, the method further includes determining, such as via processing circuitry 84 and/or PDCCH decode unit 34, the assumed at least one CFI from a table. In some embodiments, the subset of possible aggregation levels correspond to aggregation levels where performance is determined to be limited by the PCFICH decoding.

In some embodiments, the assumed at least one CFI is based at least in part on at least one decoding metric. In some embodiments, an order of which the assumed at least one CFI is attempted is further based at least in part on at least one of a cell bandwidth and a traffic type. In some embodiments, the performing the blind decoding of the PDCCH further comprises performing, such as via processing circuitry 84 and/or PDCCH decode unit 34, successive blind decoding attempts assuming a different CFI of the at least one CFI for each successive blind decoding attempt. In some embodiments, the method further includes, in response to determining that the PCFICH is not correctly decoded, performing, such as via processing circuitry 84 and/or PDCCH decode unit 34, the blind decoding of the PDCCH only for a subset of possible aggregation levels, the subset of possible aggregation levels corresponding to the aggregation levels in which performance is determined to be limited by the PCFICH decoding.

Referring to FIG. 14, in some embodiments, the process includes receiving and decoding the PCFICH (block S138). The WD 22 then determines if the PCFICH is correctly decoded (block S140). In one embodiment the assessment as to whether the PCFICH was correctly decoded or not may be based on the decoding metric of soft-values from the demodulator. In one specific embodiment the decoding metrics of the different code words may be compared to assess whether the PCFICH was correctly decoded. If the PCFICH is considered to be correctly decoded, blind decoding is performed (block S142). As an example, a search for a valid physical downlink control channel (PDCCH) candidate is performed assuming a number of symbols of the PDCCH channel indicated by a control format indicator (CFI) of the PCFICH. If the PCFICH is not considered to be correctly decoded, in one

embodiment, the blind decoding of the PDCCH is performed only for a subset of possible aggregation levels. In some embodiments, blind decoding is only performed for subset of possible aggregation levels where performance is considered limited by PCFICH decoding.

If the PCFICH is not correctly decoded, the probability that AL4 is decodable is limited. This considers that the PCFICH and the PDCCH are sent at the same point in time, or at most separated by a few OFDM symbols, thus presumably experiencing the same radio channel conditions (if mapped reasonably close in frequency). FIG. 3 only shows the average performance over signal to noise ratio (SNR) and not momentary variations, but it can be generally assumed that if the PDCCH experiences worse average performance compared to the PCFICH, the risk that the PDCCH is in error when PCFICH is in error is considerable. The probability increases the larger the performance difference between the PDCCH and the PCFICH. For AL4, if assuming the average operating point for PDCCH is le-2, the average performance for the PCFICH is around le-3. Hence, the conditional probability of PDCCH error, if PCFICH is in error, will be very high. It would be a waste of WD 22 power consumption to attempt to decode the PDCCH with this knowledge. Instead, it can only decode the ALs that are still probable to be correctly decoded, even under the condition of PCFICH error.

Consider now the blind decodes per ALs used in LTE for the PDCCH in the user-specific search space, see Table 1. In some embodiments, a total of 16 blind decodes are performed for a given DL control size attempted to be decoded.

Table 1 : Blind decodes per AL for PDCCH

AL Blind decodes

Assume also that an aggregation level 16 is introduced while keeping the blind decodes to 16 to avoid additional processing at the WD 22, see Table 2 (only one blind decode for AL8 and AL16 is assumed, instead of two blind decodes for AL8).

Table 2: Assumed blind decodes per AL for PDCCH including AL16

In cases where the PCFICH is correctly decoded, all 16 PDCCH candidates are attempted in a conventional manner.

In another embodiment, in cases where the PCFICH is not correctly decoded, and if X=4, the blind decodes per an assumed CFI (a value is assumed since the PCFICH has not been acquired) is 2 (AL4)+l (AL8)+l (AL16) = 4. Assuming further that the three CFI hypothesis is attempted, the total number of blind decodes would be 4*3=12, which is still less than the conventionally required 16 blind decodes.

In another embodiment, the WD 22 can use information after assessing whether the PCFICH is correctly decoded as described earlier together with known information such as cell bandwidth, traffic type to further reduce the average number of blind decoding.

In one specific embodiment, if the PCFICH is not correctly decoded, the WD 22 may use known information such as cell bandwidth, traffic type, and decoding metrics to set the order of CFI hypothesis (CFI =1, 2, or 3) to start the blind decoding process. In one embodiment, the WD 22 that knows that ongoing traffic is of ultra- reliable low latency communication (URLLC)/high-priority type may use known information about cell bandwidth together with decoding metrics to deduce the likelihood of correct CFI. Blind decoding based on different CFI hypotheses then follows the order of deduced likelihood.

For example, after performing the assessment if the PCFICH was correctly decoded, the WD 22 may have access to a decoding metric of each CFI hypothesis as shown in Table 3 below. Assuming that a>b»c=~d, and that the WD 22 knows that ongoing traffic is of URLLC type, the WD 22 can use the decoding metric

information alone to set the order of CFI hypothesis to start the blind decoding, i.e., CFI=l (block S144) before CFI=2 (block S146) and before CFI=3 (block S148), where X is the number of aggregation levels of the PDCCH.

Alternatively, the WD 22 may use additional information to adjust this order. For example, if cell bandwidth is smaller than some threshold value, it can use the facts that larger control channel duration (in time) is more likely required for small bandwidth and high AL for PDCCH is more likely needed for URLLC WD 22, to adjust the order of blind decoding to a new order, e.g., CFI=2 before CFI=l before CFI=3. With a proper threshold setting, this can reduce the average number of blind decoding and possible false positive of PCFICH estimation.

Table 3: Assumed blind decodes per AL for PDCCH including AL16

As described above, the relative metrics of each CFI hypothesis, in connection with prior knowledge of CFI distribution, can be used to determine in which order candidates corresponding to respective CFI hypothesis are evaluated. In another embodiment, the number of candidates corresponding to respective CFI candidates may be dependent on the combination of metrics and prior knowledge. In an example where 12 blind decodes were performed for all CFI hypotheses with AL>=4, since there was room for 16 blind decodes in total, an additional 2 decodes could be performed for the CFI candidate that is viewed as most likely.

In one embodiment, where the PCFICH is considered not correctly decoded, and decoding attempts are performed as above for different AL, a PDCCH may be spread over all CFI number of symbols and may give a successful estimate of the CFI. This new estimate of CFI may then be used for any remaining PDCCH / SPDCCH / PDSCH processing. In cases where short TTI (sTTI) is configured, the SPDCCH (Short PDCCH) search space may start in the first symbol of the subslot/slot transmission, except for some configurations where the control for the subslot/slot is sent in the PDCCH.

For SPDCCH with subslot transmission, there are two patterns used for the start of the sTTI, as shown in FIG. 15.

As is seen, for CFI equal to 1 or 3 the subslot number 1 starts in symbol 3, while if CFI is equal to 2 subslot number 1 starts in symbol 2. The WD 22 should know or assume CFI for the SPDCCH search space in sTTI#0 and sTTI#l, but not for the remaining sTTI#2-5.

An embodiment for the subslot configuration is then:

• Assess if PCFICH was correctly decoded according to previous embodiments.

If NO

o For the search space of subslot number 0, follow the embodiments of PDCCH as above.

o For the search space of subslot number 1

^■ perform blind decoding of AL>=X assuming pattern 1 (CFI=l or CFI=3)

^■ perform blind decoding of AL>=X assuming pattern 2 (CFI=2) o For the search space of subslot number two to five, perform standard blind decoding of the SPDCCH search space, thereby ignoring the CFI value. Alternatively, the invention can also be applied in this case, to reduce the number of blind decodes, even if not different hypothesis need to be used for different number of PDCCH symbols.

For SPDCCH associated with slot based PDSCH, the first slot uses the PDCCH search space, while the second slot uses a SPDCCH search space.

An embodiment for the slot configuration is:

Assess if PCFICH was correctly received according to previous embodiments.

If NO o For the search space of slot number, follow the embodiments of PDCCH as above.

o For the search space of slot number 1, perform standard blind decoding of the SPDCCH search space, thereby ignoring the CFI value. Alternatively, the invention can also be applied in this case, to reduce the number of blind decodes, even if not different hypothesis need to be used for different number of PDCCH symbols.

Thus, some embodiments allow the network to increase the aggregation level of the PDCCH to improve DL control performance in the system while leaving the PCFICH untouched to ensure backwards compatibility in the system. Even if PCFICH cannot be considered reliable, the total number of blind decodes are not increased.

Some additional embodiments may include one or more of the following: Embodiment Al . A wireless device (WD) configured to communicate with a network node, the WD configured to, and/or comprising a radio interface and/or processing circuitry configured to:

determine if a physical control format indicator channel, PCFICH, is correctly decoded;

if the PCFICH is correctly decoded, then search for a valid physical downlink control channel, PDCCH, candidate assuming a number of symbols of the PDCCH channel indicated by a control format indicator, CFI, of the PCFICH; and

if the PCFICH is determined not to be correctly decoded, then perform blind decoding of the PDCCH only for a subset of possible aggregation levels.

Embodiment A2. The WD of Embodiment Al, wherein the subset of possible aggregation levels is chosen based on known performance curves.

Embodiment A3. The WD of Embodiment Al, wherein aggregation levels where performance is considered limited by the PCFICH decoding are determined from a table.

Embodiment A4. The WD of Embodiment Al, wherein blind decoding of the PDCCH is performed assuming a CFI.

Embodiment A5. The WD of Embodiment A4, wherein the assumed CFI is based on a decoding metric. Embodiment A6. The WD of Embodiment A5, wherein the order of which the assumed CFI is attempted is further based on additional knowledge including at least one of cell bandwidth and traffic type.

Embodiment A7. The WD of Embodiment Al, wherein a PDCCH spread over a plurality of CFI symbols provides an estimate of a CFI to be used for signal processing in the wireless device.

Embodiment A8. The WD of Embodiment Al, wherein performing blind decoding includes performing successive blind decoding attempts assuming different CFIs.

Embodiment A9. The WD of Embodiment Al, wherein if the PCFICH is determined not to be correctly decoded, then the blind decoding of the PDCCH is performed only for a subset of possible aggregation levels where performance is considered limited by PCFICH decoding.

Embodiment B 1. A method implemented in a wireless device (WD), the method comprising:

determining if a physical control format indicator channel, PCFICH, is correctly decoded;

if the PCFICH is correctly decoded, then searching for a valid physical downlink control channel, PDCCH, candidate assuming a number of symbols of the PDCCH channel indicated by a control format indicator, CFI, of the PCFICH; and if the PCFICH is determined not to be correctly decoded, then performing blind decoding of the PDCCH only for a subset of possible aggregation levels.

Embodiment B2. The method of Embodiment Bl, wherein the subset of aggregation levels is chosen based on known performance curves.

Embodiment B3. The method of Embodiment B 1 , wherein aggregation levels where performance is considered limited by the PCFICH decoding are determined from a table.

Embodiment B4. The method of Embodiment Bl, wherein blind decoding of the PDCCH is performed assuming a CFI.

Embodiment B5. The method of Embodiment B4, wherein the assumed CFI is based on a decoding metric. Embodiment B6. The method of Embodiment B5, wherein the order of which the assumed CFI is attempted is further based on additional knowledge including at least one of cell bandwidth and traffic type.

Embodiment B7. The method of Embodiment Bl, wherein a PDCCH spread over a plurality of CFI symbols provides an estimate of a CFI to be used for signal processing in the wireless device.

Embodiment B8. The method of Embodiment Bl, wherein performing blind decoding includes performing successive blind decoding attempts assuming different CFIs.

Embodiment B9. The method of Embodiment Bl, wherein if the PCFICH is determined not to be correctly decoded, then the blind decoding of the PDCCH is performed only for a subset of possible aggregation levels where performance is considered limited by PCFICH decoding.

Embodiment Cl . A wireless device, comprising:

a memory module configured to store a physical downlink control channel, PDCCH, value; and

a PDCCH decode module configured to blindly decode a PDCCH when a physical control format indicator, PCFICH, is not correctly decoded, the blind decoding being performed only for a subset of possible aggregation levels where performance is considered limited by PCFICH decoding.

As will be appreciated by one of skill in the art, the concepts described herein may be embodied as a method, data processing system, and/or computer program product. 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.” 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.

Abbreviations that may be used in the preceding description include:

Abbreviation Explanation

AL Aggregation Level

CFI Control Format Indicator

PDCCH Physical Downlink Control Channel

PCFICH Physical Control Format Indicator Channel

PDSCH Physical Downlink Shared Channel

UE User Equipment

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 wireless device, WD (22), configured to communicate with a network node, the WD (22) comprising:

processing circuitry (84) configured to:

based on decoding a physical control format indicator channel, PCFICH, determine whether the PCFICH is correctly decoded; and

in response to determining that the PCFICH is not correctly decoded, perform blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH.

2. The WD (22) of Claim 1, wherein the processing circuitry (84) is further configured to:

in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH for a subset of possible aggregation levels of the at least one CFI.

3. The WD (22) of any one of Claims 1 and 2, wherein the processing circuitry (84) is further configured to:

in response to determining that the PCFICH is correctly decoded, perform a search for a PDCCH candidate assuming a number of symbols of the PDCCH indicated by the CFI of the PCFICH; and

in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH assuming a number of symbols of the PDCCH indicated by the assumed at least one CFI.

4. The WD (22) of any one of Claims 1-3, wherein the processing circuitry (84) is further configured to determine the assumed at least one CFI from a table.

5. The WD (22) of any one of Claims 2-4, wherein the subset of possible aggregation levels correspond to aggregation levels where performance is determined to be limited by the PCFICH decoding.

6. The WD (22) of any one of Claims 1-5, wherein the assumed at least one CFI is based at least in part on at least one decoding metric.

7. The WD (22) of any one of Claims 1-6, wherein an order of which the assumed at least one CFI is attempted is further based at least in part on at least one of a cell bandwidth and a traffic type.

8. The WD (22) of any one of Claims 1-7, wherein the processing circuitry (84) is further configured to perform the blind decoding of the PDCCH by being configured to:

perform successive blind decoding attempts assuming a different CFI of the at least one CFI for each successive blind decoding attempt.

9. The WD (22) of any one of Claims 1-8, wherein the processing circuitry (84) is further configured to:

in response to determining that the PCFICH is not correctly decoded, perform the blind decoding of the PDCCH only for a subset of possible aggregation levels, the subset of possible aggregation levels corresponding to the aggregation levels in which performance is determined to be limited by the PCFICH decoding.

10. A method for a wireless device, WD (22), the method comprising: based on decoding a physical control format indicator channel, PCFICH, determining (S134) whether the PCFICH is correctly decoded; and

in response to determining that the PCFICH is not correctly decoded, performing (S136) blind decoding of a physical downlink control channel, PDCCH, assuming at least one control format indicator, CFI, different from the CFI of the PCFICH.

11. The method of Claim 10, further comprising:

in response to determining that the PCFICH is not correctly decoded, performing the blind decoding of the PDCCH for a subset of possible aggregation levels of the at least one CFI.

12. The method of any one of Claims 10 and 11, further comprising:

in response to determining that the PCFICH is correctly decoded, performing a search for a PDCCH candidate assuming a number of symbols of the PDCCH indicated by the CFI of the PCFICH; and

in response to determining that the PCFICH is not correctly decoded, performing the blind decoding of the PDCCH assuming a number of symbols of the PDCCH indicated by the assumed at least one CFI.

13. The method of any one of Claims 10-12, further comprising determining the assumed at least one CFI from a table.

14. The method of any one of Claims 11-13, wherein the subset of possible aggregation levels correspond to aggregation levels where performance is determined to be limited by the PCFICH decoding.

15. The method of any one of Claims 10-14, wherein the assumed at least one CFI is based at least in part on at least one decoding metric.

16. The method of any one of Claims 10-15, wherein an order of which the assumed at least one CFI is attempted is further based at least in part on at least one of a cell bandwidth and a traffic type.

17. The method of any one of Claims 10-16, wherein the performing the blind decoding of the PDCCH further comprises:

performing successive blind decoding attempts assuming a different CFI of the at least one CFI for each successive blind decoding attempt.

18. The method of any one of Claims 10-17, further comprising:

in response to determining that the PCFICH is not correctly decoded, performing the blind decoding of the PDCCH only for a subset of possible aggregation levels, the subset of possible aggregation levels corresponding to the aggregation levels in which performance is determined to be limited by the PCFICH decoding.