WO2013131268A1

WO2013131268A1 - Apparatus and methods for pdcch reliability improvement to handle dl cc broken in unlicensed band

Info

Publication number: WO2013131268A1
Application number: PCT/CN2012/072097
Authority: WO
Inventors: Na WEI; Erlin Zeng; Gilles Charbit; Haiming Wang; Wei Bai; Wei Hong; Pengfei Sun
Original assignee: Renesas Mobile Corporation
Priority date: 2012-03-08
Filing date: 2012-03-08
Publication date: 2013-09-12

Abstract

A method to handle broken DL CC in an unlicensed band is described. The method includes determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The method also includes detecting in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the method includes detecting in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission. The method also includes, in response to detecting a DCI transmission, receiving, from an access point, the at least one DCI transmission. Apparatus and computer readable media are also described.

Description

APPARATUS AND METHODS FOR PDCCH RELIABILITY

IMPROVEMENT TO HANDLE DL CC BROKEN IN UNLICENSED BAND

TECHNICAL FIELD:

The exemplary and non-limiting embodiments relate generally to wireless communication systems, methods, devices and computer programs and, more specifically, relate to handling broken DL CC in an unlicensed band.

BACKGROUND:

This section is intended to provide a background or context to what is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.

The following abbreviations that may be found in the specification and/or the drawing figures are defined as follows:

3 GPP third generation partnership project

BW bandwidth

BD blind detection

CC component carrier

CCE control channel element

CDM code division multiplexing

CRS common reference signal

DCF distributed coordination function

DCI downlink control information

DL downlink (eNB towards UE)

eNB E-UTRAN Node B (evolved Node B)

EPC evolved packet core

E-UTRAN evolved UTRAN (LTE) FD frequency diversity

FDD frequency division duplex

FFT fast Fourier transform

HARQ hybrid automatic repeat request

ΓΜΤ-Α international mobile telephony-advanced

ITU international telecommunication union

ITU-R ITU radiocommunication sector

LTE long term evolution of UTRAN (E-UTRAN)

LTE-A long term evolution advanced

MAC medium access control (layer 2, L2)

MB master information block

MM/MME mobility management/mobility management entity

Node B base station

O&M operations and maintenance

OFDMA orthogonal frequency division multiple access

P-BCH physical broadcast channel

PCC primary cell carrier

PDCCH physical downlink control channel

PDCP packet data convergence protocol

PCFICH physical control format indicator channel

PDSCH physical downlink shared channel

PHICH physical HARQ indicator channel

PHY physical (layer 1, LI)

P-SCH primary synchronization channel

RACH random access channel

RAT radio access technology

REG resource element group

RLC radio link control

RRC radio resource control

RRH remote radio head

RRM radio resource management

SCC secondary cell carrier SC-FDMA single carrier, frequency division multiple access

S-GW serving gateway

SIB system information block

SINR signal to noise ratio

S-SCH secondary synchronization channel

TCC tracking component carrier

TVWS television white space

UE user equipment, such as a mobile station or mobile terminal

UL uplink (UE towards eNB)

UTRAN universal terrestrial radio access network

As is specified in 3GPP documents, LTE-A should operate in spectrum allocations of different sizes, including wider spectrum allocations than those of prior LTE releases (e.g., up to 100MHz) to achieve the peak data rate of lOOMbit/s for high mobility and 1 Gbit s for low mobility. Carrier aggregation, where two or more component carriers (CCs) are aggregated, may be used in order to support transmission bandwidths larger than 20MHz. The carrier aggregation could be contiguous or non-contiguous. This technique, as a bandwidth extension, can provide significant gains in terms of peak data rate and cell throughput as compared to non-aggregated operation.

A terminal may simultaneously receive one or multiple component carriers depending on its capabilities. A LTE-A terminal with reception capability beyond 20 MHz can simultaneously receive transmissions on multiple component carriers. A legacy terminal might receive transmissions on a single component carrier only, provided that the structure of the component carrier follows the relevant specifications. Moreover, it is required that LTE-A should be backwards compatible with older standards in the sense that a legacy terminal should be operable in the LTE-A system, and that a LTE-A terminal should be operable in a Rel-8 LTE system. Figure 1 shows an example of the carrier aggregation, where M 20MHz component carriers are combined together to form M^x20MHz BW (e.g., 5 ^χ 20MHz = 100MHz given M = 5). Legacy terminals may receive/transmit on one component carrier, whereas LTE-A terminals may receive/transmit on multiple component carriers simultaneously to achieve higher (wider) bandwidths.

With further regard to carrier aggregation, what is implied is that one eNB can effectively contain more than one cell on more than one CC (frequency carrier), and the eNB can utilize one (as in E-UTRAN Rel-8) or more cells (in an aggregated manner) when assigning resources and scheduling the UE. Some of the CC may be on a licensed spectrum band and others may be on an unlicensed spectrum band. A licensed spectrum band, supervised by operators, is a scarce resource. The scarcity of this resource along with the current licensed spectrum policy, having limited to no flexible spectrum usage, may not be enough to support a larger number of cellular devices and higher-QoS traffic in the near future. Therefore, traffic off-loading to unlicensed band, e.g., a TV white space (TVWS) band, may be an attractive solution for cellular operators.

Figure 2 is an illustration of the regulatory requirements on the TVWS bands. As shown, the bands are separated in to various TV channels 200. Of the limited channels shown, there is a low VHF band 202 covering channels 2-6; a high VHF band 204 covering channels 7-13 and an UHF band 206 covering channels 14-51 (this band extends beyond channel 51). Some channels 310 are only allowed to be used for DL transmission (fixed devices only) and some of these channels are only allowed to be used for UL transmission (e.g., channels which are adjacent to TV channel). Other channels 230 are allowed for communications between a fixed device while yet other channels 240 are not allowed. When using these kinds of carriers, frequency division duplexing (FDD) may be utilized.

LTE has been mainly designed to operate in licensed bands, where the channel is dedicated to the LTE system under regulation. However, deploying LTE in unlicensed bands has been contemplated lately in order to further enhance the LTE performance by utilizing the unlicensed band for additional bandwidth. The unlicensed band does not include license restrictions and, thus, may be shared by different radio access technology (RAT) devices. This shared band deployment has the potential to bring LTE many benefits such as:

Low cost: Given that no license is required, the extra spectrum will be gained with much lower cost;

· Flexible deployment: Similarly, as no license is mandatory in these shared bands, the system can be deployed in a flexible manner regardless of the need and application; and

^• New applications: The deployment in unlicensed band is more of an ad-hoc style compared with to the cellular infrastructure of LTE system on the licensed band. Therefore new applications can be devised in the field such as monitoring, control, telemetry, etc.

By the way of utilization the shared band, the LTE implementations can be divided into two categories: 1) a standalone utilization, where the whole LTE system is operating in shared bands; and 2) a hybrid utilization, where both licensed bands and unlicensed bands are available for the LTE system. In the hybrid utilization the LTE system may adopt dynamic strategies to utilize both types of bands.

Based on this categorization, it is expected that shared band LTE systems will face different operating scenarios to LTE systems that use only licensed bands, for example, frequent PCell breaks when deploying standalone LTE systems in TVWS with a FDD mode.

On unlicensed bands, for a standalone LTE system using FDD, there is a chance that the downlink component carrier (DL CC) or uplink component carrier (UL CC) is broken due to a number of causes. For example, the ON/OFF pattern used by the LTE system to share the resource with other systems operating on the unlicensed band, interference from other RAT devices, and various regulation requirements. When a LTE DL CC in the unlicensed band is broken this can cause a physical downlink control channel (PDCCH) error for certain UEs. With such an error, it is hard for the UE to decode information such as DL or UL grants. Additionally a broken DL CC may impact other PHY channels. The physical downlink shared channel (PDSCH) may not be used to transmit DL data. This can also cause inefficient AC /NAC feedback in a physical uplink control channel (PUCCH) due to possible "empty bits" in ACK/NACK sequence. A break in the physical broadcast channel (PBCH) may prevent transmission of a master information block (ΜΓΒ) while a break in the physical control format indicator channel (PCFICH) may prevent indicating the PDCCH domain. As noted above, a break in the PDCCH may interfere with transmitting DL assignments and/or UL assignments. Also, this could not trigger the use of a random access channel (RACH). A break in the physical HARQ indicator channel (PHICH) may prevent transmission of the HARQ feedback to an UL transmission, which is scheduled from a given DL CC.

The specified minimum performance requirements for PCFICH and PDCCH may be the same as in traditional LTE systems. A standalone LTE systems on unlicensed bands may use small cell configurations (e.g., similar to a HeNB or pico cells) due to regulatory requirements on ISM bands and TVWS bands. If so, the PDCCH domain could be pre-determined by specification, which removes the need for PCFICH.

The specified minimum performance requirements for demodulation of ΜΓΒ on PBCH (e.g., -6.1 dB for single transmission (Tx) configuration) are much higher than that for the PCFICH/PDCCH (e.g., -1.7 dB for single Tx configuration) due to a 40 ms repetition and strong coding. Such ΜΓΒ detection in the UE can be done following P/S-SCH detection at interference levels significantly higher than that for the PCFICH/PDCCH. If such detection is not possible then the UE cannot synchronized in time and frequency (as needed for FFT windowing) and, thus, the UE cannot receive basic system information (e.g.., DL bandwidth configuration, System Frame Number, PHICH configuration), which are perquisites for UE before it can do anything else.

In the existing LTE system, there are some techniques to ensure certain performance target of PDCCH. For example, different aggregation levels, e.g., L = 1 , 2, 4, and 8, are defined to provide different effective coding rates for the DCI. This allows the eNB to schedule L - 8 for the lowest coding rate if the signal to noise ratio (SINR) is very low. Alternatively, for a given CC, a PDCCH signal can be mapped in a distributed manner in the time and f equency domain, by means of resource element group (REG) level interleaving to provide a degree of diversity gain. In coordinated silencing for LTE HeNB deployment on TVWS using carrier aggregation, the eNB/He B supports primary, secondary (licensed) and supplementary (TVWS) cell communication to allow the eNB/HeNB and UE to communicate with each other over the licensed band only, or, over both licensed and unlicensed bands simultaneously. Since the licensed band may be used for the Primary cell, then the proposed LTE system is not a standalone LTE system, and do not apply to the problem of broken CC in a standalone LTE system.

These known techniques do not solve the issue of broken CC in unlicensed band, as for a given time period one CC may be interfered more than another, which means interleaving within a single CC or having a lower encoding rate cannot ensure satisfactory PDCCH performance.

What is needed is a way to improve the PDCCH reliability in case broken CC conditions apply in a standalone LTE system. With improved PDCCH reliability, the DL or UL assignment or RACH trigger can work properly.

SUMMARY

The below summary section is intended to be merely exemplary and non-limiting. The foregoing and other problems are overcome, and other advantages are realized, by the use of the exemplary embodiments.

In a first aspect thereof an exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The method also includes detecting in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the method includes detecting in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission. The method also includes, in response to detecting a DCI transmission, receiving, from an eNB, the at least one DCI transmission.

In a further aspect thereof an exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes receiving, in a first subframe, a DCI transmission in a first CC in an unlicensed band. The method also includes determining, based on a hopping pattern, a second CC in the unlicensed band and receiving, in a second subframe, a DCI transmission in the second CC.

In another aspect thereof an exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The method includes selecting a first CCE in the search space. The method also includes transmitting, from an eNB to at least one UE, a DCI transmission in the first CCE.

i a further aspect thereof an exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes transmitting, in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The method includes determining based on a hopping pattern, a second CC in the unlicensed band. The method also includes transmitting, in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

In another aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to determine a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The actions also include to detect in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the actions include to detect in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission. The actions also include, in response to detecting a DCI transmission, to receive, from an eNB, the at least one DCI transmission.

In a further aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to receive, in a first subframe, a DCI transmission in a first CC in an unlicensed band. The actions also include to determine, based on a hopping pattern, a second CC in the unlicensed band and to receive, in a second subframe, a DCI transmission in the second CC.

In another aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to determine a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The actions include to select a first CCE in the search space. The actions also include to transmit, f om an eNB to at least one UE, a DCI transmission in the first CCE.

In a further aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to transmit, in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The actions include to determine based on a hopping pattern, a second CC in the unlicensed band. The actions also include to transmit, in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

In another aspect thereof an exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The actions also include detecting in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the actions include detecting in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission. The actions also include, in response to detecting a DCI transmission, receiving, from an e B, the at least one DCI transmission.

In a further aspect thereof an exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include receiving, in a first subframe, a DCI transmission in a first CC in an unlicensed band. The actions also include determining, based on a hopping pattern, a second CC in the unlicensed band and receiving, in a second subframe, a DCI transmission in the second CC.

In another aspect thereof an exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The actions include selecting a first CCE in the search space. The actions also include transmitting, from an eNB to at least one UE, a DCI transmission in the first CCE.

In a further aspect thereof an exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include transmitting, in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The actions include determining based on a hopping pattern, a second CC in the unlicensed band. The actions also include transmitting, in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

In another aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The apparatus also includes means for detecting in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. The apparatus include means for detecting in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission in response to not detecting a DCI transmission. The apparatus also includes means for receiving, from an eNB, the at least one DCI transmission in response to detecting a DCI transmission.

In a further aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for receiving, in a first subframe, a DCI transmission in a first CC in an unlicensed band. The apparatus also includes means for determining, based on a hopping pattern, a second CC in the unlicensed band and means for receiving, in a second subframe, a DCI transmission in the second CC.

In another aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The apparatus includes means for selecting a first CCE in the search space. The apparatus also includes means for transmitting, from an eNB to at least one UE, a DCI transmission in the first CCE.

In a further aspect thereof an exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for transmitting, in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The apparatus includes means for determining based on a hopping pattern, a second CC in the unlicensed band. The apparatus also includes means for transmitting, in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of exemplary embodiments are made more evident the following Detailed Description, when read in conjunction with the attac e Drawing Figures, wherein:

Figure 1 shows an example of carrier aggregation as proposed for the LTE-A system.

Figure 2 is an illustration of the regulatory requirements on the TVWS bands.

Figure 3 shows a simplified block diagram of exemplary electronic devices that are suitable for use in practicing various exemplary embodiments.

Figure 4 illustrates an exemplary PDCCH search space in accordance with an embodiment.

Figure 5 shows a simplified block diagram of processing for one CCflag and DCI format.

Figure 6 illustrates an exemplary DL CC hopping in accordance with an embodiment.

Figure 7 is a logic flow diagram that illustrates the operation of an exemplary method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with various exemplary embodiments.

Figure 8 is another logic flow diagram that illustrates the operation of an exemplary method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with various exemplary embodiments.

Figure 9 is a further logic flow diagram that illustrates the operation of an exemplary method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with various exemplary embodiments.

Figure 10 is another logic flow diagram that illustrates the operation of an exemplary method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with various exemplary embodiments.

DETAILED DESCRIPTION

Various exemplary embodiments enable a standalone LTE system operating in an unlicensed band to improve the reliability in CCs used for PDCCH. Thus, the standalone LTE system may be able to handle situations where one or more DL CC are broken. Additionally, PDCCH reliability may be improved for different scenarios in unlicensed band, for example, where some of the DL CC in the unlicensed bands are more reliable than other DL CC and where all DL CC are equally reliable/unstable.

Also, once the PDCCH is correctly detected, it will be possible to transmit/receive signals such as PHICH, PDSCH or PUSCH as they can be scheduled via the PDCCH on DL CCs (PHICH and PDSCH) and UL CCs (PUCCH and PUSCH) which are not broken. The UL grant for PUSCH may be indicated to a UE by DCI format. The PUCCH transmission power command (TPC) may also be indicated to the UE by DCI format, though resources used for PUCCH transmissions and PUCCH format may be configured by dedicated signaling. Thus, PUSCH/PUCCH transmissions can be properly scheduled even if the SIB2 linked DL is experiencing bad quality/broken.

Before describing in further detail various exemplary embodiments, reference is made to Figure 3 for illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing exemplary embodiments.

In the wireless system 330 of Figure 3, a wireless network 335 is adapted for communication over a wireless link 332 with an apparatus, such as a mobile communication device which may be referred to as a UE 310, via a network access node, such as a Node B (base station), and more specifically an eNB 320.

The UE 310 includes a controller, such as a computer or a data processor (DP) 314, a computer-readable memory medium embodied as a memory (MEM) 316 that stores a program of computer instructions (PROG) 318, and a suitable wireless interface, such as radio frequency (RF) transceiver 312, for bidirectional wireless communications with the eNB 320 via one or more antennas and/or via one or more radio access technologies (RATs).

The eNB 320 also includes a controller, such as a computer or a data processor (DP) 324, a computer-readable memory medium embodied as a memory (MEM) 326 that stores a program of computer instructions (PROG) 328, and a suitable wireless interface, such as RF transceiver 322, for communication with the UE 310 via one or more antennas and/or via one or more radio access technologies (RATs).

At least one of the PROGs 318 and 328 is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with exemplary embodiments, as will be discussed below in greater detail. That is, various exemplary embodiments may be implemented at least in part by computer software executable by the DP 314 of the UE 310; and/or by the DP 324 of the eNB 320, or by hardware, or by a combination of software and hardware (and firmware).

The UE 310 and the eNB 320 may also include dedicated processors, for example DCI processor 315 and DCI processor 325.

In general, the various embodiments of the UE 310 can include, but are not limited to, cellular telephones, tablets having wireless communication capabilities, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

The computer readable MEMs 316 and 326 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The DPs 314 and 324 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multicore processor architecture, as non-limiting examples. The wireless interfaces (e.g., RF transceivers 312 and 322) may be of any type suitable to the local technical environment and may be implemented using any suitable communication technology such as individual transmitters, receivers, transceivers or a combination of such components. hi a first embodiment, multipIe-CC PDCCH may be scheduled. The eNB decides in which subframe and CC the PDCCH signal is scheduled. Based on the interference condition, eNB can choose the best CC for PDCCH (which may be transmitted on one CC). The UE monitors a number of CC in order to locate the PDCCH. The HE may perform blind detections of the CC within a limited PDCCH search space. The PDCCH search space is defined so that the PDCCH candidates can be located in more than one CC. This limits the total number of blind detections a UE may attempt. The eNB can also configure or define how many CCs and which CC the UE shall try blind detections and/or the number of blind detections the UE may perform and the location of PDCCH candidates (e.g., the PDCCH search space) for a given CC. The eNB may also provide possible configurations of the DCI format.

The PDCCH candidates can be blindly detected by the UE on more than one CCs based on a definition of the PDCCH searching space. This makes it possible that, if a subset of the active DL CCs are be unreliable, the eNB can simply schedule the PDCCH on good CCs (e.g., those that are not broken/experiencing excessive interference). This avoids delays caused by attempting to inform the UE of the changes which may not necessary be received by the UE due to the unreliable DL CCs. This allows the eNB to adapt to a fast-changing interference pattern, since an interference-aware eNB can adjust the PDCCH scheduling accordingly.

Figure 4 illustrates an exemplary PDCCH search space 440 in accordance with an embodiment. As shown, three CC, CC #1 430, CC #2 434 and CC #3 438 may include PDCCH candidates in a single subframe. Each CC is subdivided into control channel elements (CCEs). A subset of the CCE in each CC are PDCCH candidates. A candidate can be, as non-limiting examples, a single CCE (440), two CCE (450) or 4 CCE (460).

The UE may be permitted (e.g., by configuration from the eNB) a limited number of blind detections. These blind detections (BDs) may be evenly distributed between the CC (as shown) or distributed unevenly. As shown in Figure 4, there are 66 candidates evenly spread between the three CC (22 to each CC). Thus, at a given time, the UE may monitor the 22 candidates in each CC in order to determine which the eNB decides to use for PDCCH scheduling. In case some CCs are interfered, the PDCCH can still go through. Additionally, the total number of BDs is prevented can be tailored to the UEs capabilities to ensure a UE is not forced to perform an excessive number of BDs. If more BDs are allowed for advanced UEs, more candidates can be defined to each CC; however, if the UE can handle a limited number of BDs (e.g., in an older UE) the number of candidates may be limited to those that the UE can handle. When the PDCCH candidates are defined in multiple CCs, the UE can perform channel estimation and decoding on multiple CCs (although the total number of BDs does not increase).

In a second embodiment, PDCCH signals with the same or different contents are transmitted from more than one CCs. This provides PDCCH frequency diversity (FD) against interference. Additionally, the UE receiving the PDCCH signals may perform soft bit combining of the signals to provide channel coding gain.

The eNB may define a fixed linkage between the PDCCH candidate from one CC and the candidate(s) from the other CC(s). This helps prevent increasing the number of blind detections performed by the UE. The eNB may also add a flag/bitmap CCflag that is separately encoded and appended to the DCI format. The flag may be UE specific, or UE-group based, or for all UEs in the cell based on eNB knowledge of the interfered CCs. The flag can allow determination of the CCs which are not broken before soft bit combining of the DCI format on the "un-broken" CCs proceeds.

In order to lower the PDCCH search complexity a UE may attempt a limited number of DB (e.g., 66) jointly in a first CC #1 for a given PDCCH candidate, candidate #kl, and another PDCCH candidate on a second CC, candidate #k2, and another PDCCH candidate on a third CC, candidate #k3. The UE then tries a soft combination of the decoded bits of candidates #kl, #k2 and #k3, which allows for extra coding gain and frequency diversity. The UE may also perform CRC checking after the soft decision combining and hardening of the resulting soft bits (signaling bits for the DCI format and CRC bits) to determine whether the PDCCH has been reliably decoded. Due to a fixed linkage between the candidates, e.g., between #kl-#k2 and #kl-#k3, the total number of BDs done jointly for the candidate #kl, #k2 and #k3 will still be limited (e.g., to 66). However, for each BD, the UE has to decode three PDCCH coding blocks- the BD candidate and the two linked candidate. This increased the computational decoding complexity since the candidate soft-decision PDCCH decodings are followed by soft-decision combining.

The eNB may use the FD/soft decoding gain to schedule PDCCH with lower aggregation levels. Each candidate PDCCH can be encoded and rate matched to aggregated CCEs (e.g., 1, 2, 4 or 8 CCEs), before the joint BD attempts followed by soft-decision combining over the multiple CCs is performed. If fewer broken CCs are experienced, a higher PDCCH decoding performance will be experienced. The eNB may also configure a smaller UE- specific search space size to overall reduce the BD complexity (the same number of BD attempts, but overall fewer BD done by UE since there is a smaller search). The search space may be a UE-specific search space tailored for a given UE based on the interference experienced by that UE.

Figure 5 shows a simplified block diagram of processing for one CCfiag and DCI format. The flag/bitmap CCfiag 510 is used to indicate how many CCs will used for the transmission of a PDCCH. The CCfiag 510 and the DCI format 515 are separately CRC attached. The CCs can be appended/concatenated to the DCI format 515 used to give the grants. After separate CRC coding 530 and channel coding 535, the encoded CCfiag and DCI format are concatenated 550 before rate matching and mapping to CCEs 560. The rate matching allows fitting of a rate-matched sequence to the CCEs with an aggregation (e.g., level 1, 2, 4, or 8 CCEs). One CCE may be 36 resource elements. The flag may be UE specific or intended for all the UEs, depending on whether the eNB indicates that some CCs are broken for a UE, a group of UEs or all UEs in the LTE system on the unlicensed band.

The CCfiag may be indicated via dynamical signaling, thus, the indication of broken CCs is more flexible that via configuration of ON/OFF patterns via higher-layer signaling. The eNB may gain knowledge of the interfered CCs during an ON duration period, for example, based on UE reporting. Since the flag is detected blindly and once decoded, in order to avoid increasing PDDCH detection failure, the CCflag may be block encoded (e.g., to allow error detection and error correction with very low erroneous probability) with significantly stronger coding than used for DCI and concatenated with the separately encoded DCI format. The parity check bits of the encoded CCflag may also be scrambled with a UE-specific NTI to allow the UE to determine whether the CCflag is for it.

The UE blindly detects the CCflag across all the configured carriers during an overlapping ON period with FD/soft decision gain in order to determine which CC are used for the grants. The UE then detects the DCI format in a known carrier and a known physical resources (e.g., no BD attempts are needed anymore, as already done during determination of the CCflag) with higher FD/soft decision gain as only the DCI formats on the PDCCHs on a valid CCs are soft-decision combined based on the CCflag to get the grants indicated on the DCI format.

If UE-specific scrambling is used in the CCflag encoding, then the UE performs DCI decoding if the CCflag is intended for the UE. The DCI decoding may use weighted soft decision combining of PDCCHs, in order to recover from a wrong CCflag detection if at least one reliable CC is used.

If the CCs in the unlicensed band are equally reliable/unstable, the FD provided by using multiple CC helps recover failures if any CC are broken (provided enough CC are good). If the eNB knows which CC are more reliable, the eNB may select the CC used to reduce the chances that one or more CC are broken.

In a third embodiment, the PDCCH may be hop over different CC. In each SF, the PDCCH for an UL grant (e.g., a grant of an UL carrier) is provided on a DL CC, however, the DL CC may change over SFs. The eNB may configure an ON/OFF of such hopping. Additionally, the hopping pattern and how frequent such hopping occurs are configurable for each UE. This allows the hopping to handle the different interference levels that may be seen by each UE. The eNB may configure the ON/OFF of the control signaling hopping over different CCs. When most of the DL unlicensed band carriers are equally reliable/unstable, the hopping pattern may be selected randomly and hops are approximately evenly distributed among a group of carriers during an overlapping ON duration. Alternatively, if some carriers are more reliable than others (though this may change over time), the eNB may signal from time to time to direct the control hopping to the reliable CC among a group of carriers during an overlapping ON duration. The pattern may indicate a sequence of CC to be used, e.g., CC #1, CC #2, CC #3, CC #1, CC #2, etc. The sequence may be indicated by a reference (e.g., an index of a table of possible patterns). Additionally, the eNB may provide details regarding how often the CC will be changed, for example, the DL CC is hopped after 1, 2 or 3 SF. The eNB may provide the details of the hopping pattern to the UE so that the UE knows where to check for the DL CC in each subframe.

As noted above, if the CCs in the unlicensed band are equally reliable/unstable, the eNB may randomly assign a hopping pattern to be used. If the hopping pattern evenly distributes the hops to all CCs, there is a chance that the hop lands on a broken/bad CC. However, even if this occurs, the DL CC will hop off the broken CC to another CC limiting the disruption. If the eNB knows which CC are more reliable, the eNB may select a hopping pattern that is semi-static (e.g., staying on a given CC longer) and/or distributes the hop so that the reliable CC are used more often. For example, if CC #1 and CC #2 are reliable, the hopping pattern may simply alternate between the two.

As the DL interference conditions are typically UE-specific, the control hopping may depend on certain UE's neighbor systems' interference level. The configuration may also be UE-specific. To minimize the impact on CC linkage, SEB2 linkage DL CC may be used for PL measurement, timing advance (TA) reference, RACH link, PHICH link, etc. Additionally, UL grant linkage and A/N feedback on a PHICH may depend on the actual DL CC used. Figure 6 illustrates an exemplary DL CC hopping in accordance with an embodiment. As shown, three CC, CC#1 620, CC #2 630 and CC #3 640 may be used for the DL CC. Each CC is subdivided into control channel elements (CCEs). In the first subframe, SF #1 612, CC #1 620 is used for the DL CC. In SF #2 614, the DL CC hops in accordance with a hopping pattern, and CC #2 630 is used for the DL CC. Again, in SF #3 616, the DL CC hops. In SF #3 616, CC #3 640 is used. The pattern may then repeat (for example, in the next subframe CC #1 620 would be used for the DL CC). As noted above, if the CCs in the unlicensed band are equally reliable/unstable, the eNB may randomly assign a hopping pattern to be used. If the hopping pattern evenly distributes the hops to all CCs, there is a chance that the hop lands on a broken/bad CC. However, even if this occurs, the DL CC will hop off the broken CC to another CC limiting the disruption. If the eNB knows which CC are more reliable, the eNB may select a hopping pattern that is semi-static (e.g., staying on a given CC longer) and/or distributes the hop so that the reliable CC are used more often. For example, if CC #1 and CC #2 are reliable, the hopping pattern may simply alternate between the two.

While the exemplary embodiments have been described above in the context of the PDCCH, it should be appreciated that other signaling may be based on the PDCCH signaling, for example, PHICH signaling, etc. In the first embodiment, when UE detects a PDCCH in a DL CC, the UE will receive a PHICH signal from the same DL CC. The exact PHICH resource on that DL CC can be predefined or configured via higher layer. If the PHICH resource is to be linked to PUSCH resources the eNB can make sure that no PHICH collision would happen. In the second embodiment, PHICH signals may be transmitted to a UE on multiple DL CCs, just as PDCCHs. In this case, the PHICH resources may be predefined or configured via higher layer. In the third embodiment, the PHICH signal can follow the same hopping mechanism/pattern as the PDCCH.

The hopping pattern may also change which CCE is used. This may be fixed CCE within each CC (e.g., a set CCE each time a given CC is used), or may change regardless of the CC used. Additionally, the hopping pattern may hope the CCE used within the same CC between subframes, for example, in first subframe a first CCE in a given CC is used and in the next subframe a different CCE in the same CC is used. Based on the foregoing it should be apparent that the exemplary embodiments provide a method, apparatus and computer program(s) for handling broken DL CC in an unlicensed band.

Figure 7 is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with an exemplary embodiment. In accordance with these exemplary embodiments a method performs, at Block 710, a step of determining a search space of PDCCH candidate CCEs. The search space comprises a subset of CCE in a plurality of CCs in an unlicensed band. At Block 720, the method performs a step of detecting in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the method performs a step of detecting in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission at Block 730. At block 740, in response to detecting a DCI transmission, the method performs a step of receiving, from an access point (e.g., an eNB), the at least one DCI transmission

Figure 8 is another logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with an exemplary embodiment. In accordance with these exemplary embodiments a method performs, at Block 810, a step of determining a search space of PDCCH candidate CCEs. The search space comprises a subset of CCE in a plurality of CCs on an unlicensed band. The method performs, at Block 820, a step of selecting a first CCE in the search space. At Block 830, the method performs a step of transmitting, from an access point (e.g., an eNB) to at least one mobile device (e.g., a UE), a DCI transmission in the first CCE. Figure 9 is a further logic flow diagram that illustrates the operation of an exemplary method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with various exemplary embodiments. In accordance with these exemplary embodiments a method performs, at Block 910, a step of determining a search space of PDCCH candidate CCEs. The search space comprises a subset of CCE in a plurality of CCs on an unlicensed band. At Block 920, the method performs a step of selecting a first CCE in the search space. The method performs a step of transmitting, from an access point to at least one mobile device, a DCI transmission in the first CCE at Block 930.

Figure 10 is another logic flow diagram that illustrates the operation of an exemplary method, and a result of execution of computer program instructions embodied on a computer readable memory, in accordance with various exemplary embodiments. In accordance with these exemplary embodiments a method performs, at Block 1010, a step of transmitting, in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. At Block 1020, the method performs a step of determining based on a hopping pattern, a second CC in the unlicensed band. The method also performs a step of transmitting, in a second subframe, a DCI transmission in the second CC of a plurality of CCs at Block 1030.

The various blocks shown in Figures 7-10 may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s). A first exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes determining (e.g., by a processor) a search space of PDCCH candidate CCEs. The search space includes a subset of CCEs in a plurality of CCs in an unlicensed band. The method also includes detecting (e.g., by a processor) in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the method includes detecting (e.g., by a processor) in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission. The method also includes, in response to detecting a DCI transmission, receiving (e.g., by a receiver), from an access point, the at least one DCI transmission.

In a further exemplary embodiment of the method above, the method also includes receiving an indication of the search space location.

In another exemplary embodiment of any one of the methods above, receiving the at least one DCI transmission includes receiving the at least one DCI transmission in a first CCE. The method also includes receiving a PHICH signal in the first CCE.

In a further exemplary embodiment of any one of the methods above, receiving the at least one DCI transmission, includes receiving a plurality of DCI transmissions in a plurality of PDCCH candidate CCE. The method also includes decoding bits of the plurality of DCI transmissions; and soft combining the decoding bits of the plurality of DCI transmissions. At least one PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a first CC and at least one other PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a second CC. The plurality of PDCCH candidate CCE may include a first linked candidate CCE in a first CC and a second linked candidate CCE in a second CC. In response to detecting a DCI transmission in the first linked candidate CCE, the method includes determining the second linked candidate CCE in the second CC based on the first linked candidate CCE in a first CC; and receiving, from the access point, the at least one DCI transmission of the plurality of DCI transmissions in the second linked candidate CCE in the second CC.

hi another exemplary embodiment of any one of the methods above, the method also includes determining whether the at least one PDCCH candidate CCE includes a flag indicating a number of CCs which carry DCI transmissions. The flag may also indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format.

A further exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes receivmg (e.g., by a receiver), in a first subframe. a DCI transmission in a first CC in an unlicensed band. The method also includes determining (e.g., by a processor), based on a hopping pattern, a second CC in the unlicensed band and receiving (e.g., by a receiver), in a second subframe, a DCI transmission in the second CC.

In another exemplary embodiment of the method above, the method also mcludes receiving the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

In a further exemplary embodiment of any one of the methods above, the hopping pattern randomly distributes the DCI transmission among CCs in the unlicensed band. A further exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes determining (e.g., by a processor) a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The method includes selecting (e.g., by a processor) a first CCE in the search space. The method also includes transmitting (e.g., by a transmitter), from an access point to at least one mobile device, a DCI transmission in the first CCE.

In another exemplary embodiment of the method above, the method also includes transmitting, from the access point to the at least one mobile device, an indication of the search space.

In a further exemplary embodiment of any one of the methods above, the method also includes transmitting a PHICH signal in the first CCE.

In another exemplary embodiment of any one of the methods above, the method also includes selecting at least one other CCE in the search space; and transmitting, from the access point to at least one mobile device, at least one other DCI transmission in the at least one other CCE. The first CCE may be located in a first CC and at least one of the at least one other CCE is located in a second CC. If the first CCE is a first linked CCE, selecting the at least one other CCE may include selecting a second linked CCE in the second CC based on the first linked CCE in the first CC.

In a further exemplary embodiment of any one of the methods above, transmitting the DCI transmission includes transmitting, in the CCE, a flag indicating a number of CCs which the DCI transmission and the at least one other DCI transmission. The flag may indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format indication. In another exemplary embodiment of any one of the methods above, selecting the first CCE is based at least in part on interference conditions in the subset of CCE.

A further exemplary embodiment provides a method to handle broken DL CC in an unlicensed band. The method includes transmitting (e.g., by a transmitter), in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The method includes determining (e.g., by a processor) based on a hopping pattern, a second CC in the unlicensed band. The method also includes transmitting (e.g., by a transmitter), in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

In another exemplary embodiment of the method above, the method also includes transmitting the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

In a further exemplary embodiment of any one of the methods above, the hopping pattern randomly distributes the DCI transmission among the plurality of CCs in the unlicensed band.

In another exemplary embodiment of any one of the methods above, the method also includes selecting the hopping pattern based at least in part on interference conditions in the of a plurality of CCs.

A further exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to determine a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The actions also include to detect in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the actions include to detect in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission. The actions also include, in response to detectin^g a DCI transmission, to receive, from an access point, the at least one DCI transmission.

In another exemplary embodiment of the apparatus above, the actions also include to receive an indication of the search space location.

In a further exemplary embodiment of any one of the apparatus above, receiving the at least one DCI transmission includes receiving the at least one DCI transmission in a first CCE. The actions also include to receive a PHICH signal in the first CCE.

In another exemplary embodiment of any one of the apparatus above, receiving the at least one DCI transmission, includes receiving a plurality of DCI transmissions in a plurality of PDCCH candidate CCE. The actions also include to decode bits of the plurality of DCI transmissions; and to soft combine the decoding bits of the plurality of DCI transmissions. At least one PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a first CC and at least one other PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a second CC. The plurality of PDCCH candidate CCE may include a first linked candidate CCE in a first CC and a second linked candidate CCE in a second CC. In response to detecting a DCI transmission in the first linked candidate CCE, the actions include to determine the second linked candidate CCE in the second CC based on the first linked candidate CCE in a first CC; and to receive, from the access point, the at least one DCI transmission of the plurality of DCI transmissions in the second linked candidate CCE in the second CC.

In a further exemplary embodiment of any one of the apparatus above, the actions include to determine whether the at least one PDCCH candidate CCE includes a flag indicating a number of CCs which carry DCI transmissions. The flag may also indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format.

In another exemplary embodiment of any one of the apparatus above, the apparatus is embodied in a mobile device.

In a further exemplary embodiment of any one of the apparatus above, the apparatus is embodied in an integrated circuit. Another exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to receive, in a first subframe, a DCI transmission in a first CC in an unlicensed band. The actions also include to determine, based on a hopping pattern, a second CC in the unlicensed band and to receive, in a second subframe, a DCI transmission in the second CC.

In a further exemplary embodiment of the apparatus above, the actions also include to receive the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

In another exemplary embodiment of any one of the apparatus above, the hopping pattern randomly distributes the DCI transmission among CCs in the unlicensed band.

In a further exemplary embodiment of any one of the apparatus above, the apparatus is embodied in a mobile device.

In another exemplary embodiment of any one of the apparatus above, the apparatus is embodied in an integrated circuit.

A further exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to determine a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The actions include to select a first CCE in the search space. The actions also include to transmit, from an access point to at least one mobile device, a DCI transmission in the first CCE.

In another exemplary embodiment of the apparatus above, the actions also include to transmit, from the access point to the at least one mobile device, an indication of the search space.

In a further exemplary embodiment of any one of the apparatus above, the actions also include to transmit a PHICH signal in the first CCE.

In another exemplary embodiment of any one of the apparatus above, the actions also include to select at least one other CCE in the search space; and to transmit, from the access point to at least one mobile device, at least one other DCI transmission in the at least one other CCE. The first CCE may be located in a first CC and at least one of the at least one other CCE is located in a second CC. If the first CCE is a first linked CCE, selecting the at least one other CCE may include selecting a second linked CCE in the second CC based on the first linked CCE in the first CC.

In a further exemplary embodiment of any one of the apparatus above, transmitting the DCI transmission includes transmitting, in the CCE, a flag indicating a number of CCs which the DCI transmission and the at least one other DCI transmission. The flag may indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format indication.

In another exemplary embodiment of any one of the apparatus above, selecting the first CCE is based at least in part on interference conditions in the subset of CCE.

h another exemplary embodiment of any one of the apparatus above, the apparatus is embodied in an integrated circuit.

A further exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes a processor and memory storing computer program code. The memory and the computer program code are configured to, with the processor, cause the apparatus to perform actions. The actions include to transmit, in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The actions include to determine based on a hopping pattern, a second CC in the unlicensed band. The actions also include to transmit, in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

In another exemplary embodiment of the apparatus above, the actions also include to transmit the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

In a further exemplary embodiment of any one of the apparatus above, the hopping pattern randomly distributes the DCI transmission among the plurality of CCs in the unlicensed band.

In another exemplary embodiment of any one of the apparatus above, the actions also include to select the hopping pattern based at least in part on interference conditions in the of a plurality of CCs.

A further exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The actions also include detecting in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. In response to not detecting a DCI transmission, the actions include detecting in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission. The actions also include, in response to detecting a DCI transmission, receiving, from an access point, the at least one DCI transmission.

In another exemplary embodiment of the computer readable medium above, the actions also include receiving an indication of the search space location.

In a further exemplary embodiment of any one of the computer readable medium above, receiving the at least one DCI transmission includes receiving the at least one DCI transmission in a first CCE. The actions also include receiving a PHICH signal in the first CCE.

In another exemplary embodiment of any one of the computer readable media above, receiving the at least one DCI transmission, includes receiving a plurality of DCI transmissions in a plurality of PDCCH candidate CCE. The actions also include decoding bits of the plurality of DCI transmissions; and soft combining the decoding bits of the plurality of DCI transmissions. At least one PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a first CC and at least one other PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a second CC. The plurality of PDCCH candidate CCE may include a first linked candidate CCE in a first CC and a second linked candidate CCE in a second CC. Fn response to detecting a DCI transmission in the first linked candidate CCE, the actions include determining the second linked candidate CCE in the second CC based on the first linked candidate CCE in a first CC; and receiving, from the access point, the at least one DCI transmission of the plurality of DCI transmissions in the second linked candidate CCE in the second CC.

In a further exemplary embodiment of any one of the computer readable media above, the actions also include determining whether the at least one PDCCH candidate CCE includes a flag indicating a number of CCs which carry DCI transmissions. The flag may also indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format.

In another exemplary embodiment of any one of the computer readable media above, the computer readable medium is a non-transitory computer readable medium (e.g., CD-ROM, RAM, flash memory, etc.).

A further exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include receiving, in a first subframe, a DCI transmission in a first CC in an unlicensed band. The actions also include determining, based on a hopping pattern, a second CC in the unlicensed band and receiving, in a second subframe, a DCI transmission in the second CC.

In another exemplary embodiment of the computer readable medium above, the actions also include receiving the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

In a further exemplary embodiment of any one of the computer readable media above, the hopping pattern randomly distributes the DCI transmission among CCs in the unlicensed band.

In another exemplary embodiment of any one of the computer readable media above, the computer readable medium is a non-transitory computer readable medium (e.g., CD-ROM, RAM, flash memory, etc.). A further exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include determining a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The actions include selecting a first CCE in the search space. The actions also include transmitting, from an access point to at least one mobile device, a DCI transmission in the first CCE.

In another exemplary embodiment of the computer readable medium above, the actions also include transmitting, from the access point to the at least one mobile device, an indication of the search space.

In a further exemplary embodiment of any one of the computer readable media above, the actions also include transmitting a PHICH signal in the first CCE.

In another exemplary embodiment of any one of the computer readable media above, the actions also include selecting at least one other CCE in the search space; and transmitting, from the access point to at least one mobile device, at least one other DCI transmission in the at least one other CCE. The first CCE may be located in a first CC and at least one of the at least one other CCE is located in a second CC. If the first CCE is a first linked CCE, selecting the at least one other CCE may include selecting a second linked CCE in the second CC based on the first linked CCE in the first CC.

In a further exemplary embodiment of any one of the computer readable media above, transmitting the DCI transmission includes transmitting, in the CCE, a flag indicating a number of CCs which the DCI transmission and the at least one other DCI transmission. The flag may indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format indication.

In another exemplary embodiment of any one of the computer readable media above, selecting the first CCE is based at least in part on interference conditions in the subset of CCE.

In a further exemplary embodiment of any one of the computer readable media above, the computer readable medium is a non-transitory computer readable medium (e.g., CD-ROM, RAM, flash memory, etc.). Another exemplary embodiment provides a computer readable medium to handle broken DL CC in an unlicensed band. The computer readable medium is tangibly encoded with a computer program executable by a processor to perform actions. The actions include transmitting, in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The actions include determining based on a hopping pattern, a second CC in the unlicensed band. The actions also include transmitting, in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

In a further exemplary embodiment of the computer readable medium above, the actions also include transmitting the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

In another exemplary embodiment of any one of the computer readable media above, the hopping pattern randomly distributes the DCI transmission among the plurality of CCs in the unlicensed band.

In a further exemplary embodiment of any one of the computer readable media above, the actions also include selecting the hopping pattern based at least in part on interference conditions in the of a plurality of CCs.

A further exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for determining (e.g., a processor) a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs in an unlicensed band. The apparatus also includes means for detecting (e.g., a processor) in at least one PDCCH candidate CCE in the search space whether the at least one PDCCH candidate CCE carries a DCI transmission. The apparatus include means for detecting (e.g., a processor) in at least one other PDCCH candidate CCE in the search space whether the at least one other PDCCH candidate CCE carries at least one DCI transmission in response to not detectins a DCI transmission. The apparatus also includes means for receiving (e.g., a receiver), from an access point, the at least one DCI transmission in response to detecting a DCI transmission.

In another exemplary embodiment of the apparatus above, the apparatus also includes means for receiving an indication of the search space location.

In a further exemplary embodiment of any one of the apparatus above, the DCI transmission receiving means includes means for receiving the at least one DCI transmission in a first CCE. The apparatus also includes means for receiving a PHICH signal in the first CCE.

In another exemplary embodiment of any one of the apparatus above, the DCI transmission receiving means includes means for receiving a plurality of DCI transmissions in a plurality of PDCCH candidate CCE. The apparatus also includes means for decoding bits of the plurality of DCI transmissions; and means for soft combining the decoding bits of the plurality of DCI transmissions. At least one PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a first CC and at least one other PDCCH candidate CCE of the plurality of PDCCH candidate CCE may be located in a second CC. The plurality of PDCCH candidate CCE may include a first linked candidate CCE in a first CC and a second linked candidate CCE in a second CC. The apparatus includes means for determining the second linked candidate CCE in the second CC based on the first linked candidate CCE in a first CC in response to detecting a DCI transmission in the first linked candidate CCE; and means for receiving, from the access point, the at least one DCI transmission of the plurality of DCI transmissions in the second linked candidate CCE in the second CC.

In a further exemplary embodiment of any one of the apparatus above, the apparatus also includes means for determining whether the at least one PDCCH candidate CCE includes a flag indicating a number of CCs which carry DCI transmissions. The flag may also indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format. Another exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for receiving (e.g., a receiver), in a first subframe, a DCI transmission in a first CC in an unlicensed band. The apparatus also includes means for determining (e.g., a processor), based on a hopping pattern, a second CC in the unlicensed band and means for receiving (e.g., a receiver), in a second subframe, a DCI transmission in the second CC.

In a further exemplary embodiment of the apparatus above, the apparatus also includes means for receiving the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

A further exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for determining (e.g., a processor) a search space of PDCCH candidate CCEs. The search space includes a subset of CCE in a plurality of CCs on an unlicensed band. The apparatus includes means for selecting (e.g., a processor) a first CCE in the search space. The apparatus also includes means for transmitting (e.g., a transmitter), from an access point to at least one mobile device, a DCI transmission in the first CCE.

In another exemplary embodiment of the apparatus above, the apparatus also includes means for transmitting, from the access point to the at least one mobile device, an indication of the search space.

In a further exemplary embodiment of any one of the apparatus above, the apparatus also includes means for transmitting a PHICH signal in the first CCE.

In another exemplary embodiment of any one of the apparatus above, the apparatus also includes means for selecting at least one other CCE in the search space; and means for transmitting, from the access point to at least one mobile device, at least one other DCI transmission in the at least one other CCE. The first CCE may be located in a first CC and at least one of the at least one other CCE is located in a second CC. The selecting means may include means for selecting a second linked CCE in the second CC based on the first linked CCE in the first CC if the first CCE is a first linked CCE.

In a further exemplary embodiment of any one of the apparatus above, the transmitting means includes means for transmitting, in the CCE, a flag indicating a number of CCs which the DCI transmission and the at least one other DCI transmission. The flag may indicate an associated UE for the DCI transmission. The flag may be appended to a DCI format indication.

A further exemplary embodiment provides an apparatus to handle broken DL CC in an unlicensed band. The apparatus includes means for transmitting (e.g., a transmitter), in a first subframe, a DCI transmission in a first CC of a plurality of CCs in an unlicensed band. The apparatus includes means for determining (e.g., a processor) based on a hopping pattern, a second CC in the unlicensed band. The apparatus also includes means for transmitting (e.g., a transmitter), in a second subframe, a DCI transmission in the second CC of a plurality of CCs.

In another exemplary embodiment of the apparatus above, the apparatus also includes means for transmitting the hopping pattern. The hopping pattern indicates which CC is used for transmitting DCI transmissions in a given subframe. The hopping pattern may indicate when the CC used for DCI transmissions changes.

In a f rther exemplary embodiment of any one of the apparatus above, the hopping pattern randomly distributes the DCI transmission among the plurality of CCs in the unlicensed band.

In another exemplary embodiment of any one of the apparatus above, the apparatus also includes means for selecting the hopping pattern based at least in part on interference conditions in the of a plurality of CCs.

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although not limited thereto. While various aspects of the exemplary embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as nonlimiting examples, hardware, software, firmware, srjecial purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

It should thus be appreciated that at least some aspects of the exemplary embodiments may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments.

Various modifications and adaptations to the foregoing exemplary embodiments may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications will still fall within the scope of the non-limiting and exemplary embodiments.

For example, while the exemplary embodiments have been described above in the context of the E-UTRAN (UTRAN-LTE) system, it should be appreciated that the exemplary embodiments are not limited for use with only this one particular type of wireless communication system, and that they may be used to advantage in other wireless communication systems such as for example (WLAN, UTRA , GSM as appropriate).

It should be noted that the terms "connected," "coupled," or any variant thereof, mean any connection or coupling, either direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are "connected" or "coupled" together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be "connected" or "coupled" together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non-limiting and non-exhaustive examples. Further, the various names used for the described parameters (e.g., R TI, etc.) are not intended to be limiting in any respect, as these parameters may be identified by any suitable names. Further, the various names assigned to different channels (e.g., PUCCH, PDSCH, RACH, etc.) are not intended to be limiting in any respect, as these various channels may be identified by any suitable names.

Furthermore, some of the features of the various non-limiting and exemplary embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles, teachings and exemplary embodiments, and not in limitation thereof.

Claims

What is Claimed is:

1. A method comprising:

determining a search space of physical downlink control channel candidate control channel elements, where the search space comprises a subset of control channel element in a plurality of component carriers in an unlicensed band;

detecting in at least one physical downlink control channel candidate control channel element in the search space whether the at least one physical downlink control channel candidate control channel element carries a downlink control information transmission;

in response to not detecting a downlink control information transmission, detecting in at least one other physical downlink control channel candidate control channel element in the search space whether the at least one other physical downlink control channel candidate control channel element carries at least one downlink control information transmission; and

in response to detecting a downlink control information transmission, receiving, from an access point, the at least one downlink control information transmission.

2. The method of claim 1, further comprising receiving an indication of the search space location.

3. The method of claim 1, where receiving the at least one downlink control information transmission comprises receiving the at least one dowrdink control information transmission in a first control channel element and

the method further comprises receiving a physical hybrid automatic repeat request indicator channel signal in the first control channel element.

4. The method of claim 1 , where receiving the at least one downlink control information transmission, comprises receiving a plurality of downlink control information transmissions in a plurality of physical downlink control channel candidate control channel elements; and

the method further comprises: decoding bits of the plurality of downlink control information transmissions; and soft combining the decoding bits of the plurality of downlink control information transmissions.

5. The method of claim 4, where at least one physical downlink control channel candidate control channel element of the plurality of physical downlink control channel candidate control channel elements is located in a first component carrier and at least one other physical downlink control channel candidate control channel element of the plurality of physical downlink control channel candidate control channel elements is located in a second component carrier.

6. The method of claim 4, where the plurality of physical downlink control channel candidate control channel elements comprise a first linked candidate control channel element in a first component carrier and a second linked candidate control channel element in a second component carrier.

7. The method of claim 6, where, in response to detecting a downlink control information transmission in the first linked candidate control channel element, determining the second linked candidate control channel element in the second component carrier based on the first linked candidate control channel element in a first component carrier; and

receiving, from the access point, the at least one downlink control information transmission of the plurality of downlink control information transmissions in the second linked candidate control channel element in the second component carrier.

8. The method of claim 1, further comprising determining whether the at least one physical downlink control channel candidate control channel element comprises a flag indicating a number of component carriers which carry downlink control information transmissions.

9. The method of claim 8, where the flag further indicates an associated mobile device for the downlink control mformation transmission.

10. The method of claim 8, where the flag is appended to a downlink control information format.

11. A method comprising:

receiving, in a first subframe, a downlink control information transmission in a first component carrier in an unlicensed band;

determining based on a hopping pattern, a second component carrier in the unlicensed band; and

receiving, in a second subframe, a downlink control information transmission in the second component carrier.

12. The method of claim 11, further comprising receiving the hopping pattern, where the hopping pattern indicates which component carrier is used for transmitting downlink control information transmissions in a given subframe.

13. The method of claim 12, where the hopping pattern indicates when the component carrier used for downlink control information transmissions changes.

14. The method of claim 11, where the hopping pattern randomly distributes the downlink control information transmission among component carriers in the unlicensed band.

15. A method comprising:

determining a search space of physical downlink control channel candidate control channel elements, where the search space comprises a subset of control channel elements in a plurality of component carriers on an unlicensed band;

selecting a first control channel element in the search space; and

transmitting, from an access point to at least one mobile device, a downlink control information transmission in the first control channel element.

16. The method of claim 15, further comprising transmitting, from the access point to the at least one mobile device, an indication of the search space.

17. The method of claim 15, further comprising transmitting a physical hybrid automatic repeat request indicator channel signal in the first control channel element.

18. The method of claim 15, further comprising:

selecting at least one other control channel element in the search space; and transmitting, from an access point to at least one mobile device, at least one other downlink control information transmission in the at least one other control channel element.

19. The method of claim 18, where the first control channel element is located in a first component carrier and at least one of the at least one other control channel element is located in a second component carrier.

20. The method of claim 19, where the first control channel element is a first linked control channel element and selecting the at least one other control channel element comprises selecting a second linked control channel element in the second component carrier based on the first linked control channel element in the first component carrier.

21. The method of claim 15, where transmitting the downlink control information transmission comprises transmitting, in the first control channel element, a flag indicating a number of component carriers which the downlink control information transmission and the at least one other downlink control information transmission.

22. The method of claim 21, where the flag further indicates an associated mobile device for the downlink control information transmission.

23. The method of claim 21, where the flag is appended to a downlink control information format indication.

24. The method of claim 15, where selecting the first control channel element is based at least in part on interference conditions in the subset of control channel elements.

25. A method comprising:

transmitting, in a first subframe, a downlink control information transmission in a first component carrier of a plurality of component carriers in an unlicensed band; determining based on a hopping pattern, a second component carrier in the unlicensed band; and

transmitting, in a second subframe, a downlink control information transmission in the second component carrier of a plurality of component carriers.

26. The method of claim 25, further comprising transmitting the hopping pattern, where the hopping pattern indicates which component carrier is used for transmitting downlink control information transmissions in a given subframe.

27. The method of claim 26, where the hopping pattern indicates when the component carrier used for downlink control information transmissions changes.

28. The method of claim 25, where the hopping pattern randomly distributes the downlink control information transmission among the plurality of component carriers in the unlicensed band.

29. The method of claim 25, further comprising selecting the hopping pattern based at least in part on interference conditions in the of a plurality of component carriers.