PATENT DOCUMENT

Publication Number: US-9554283-B2
Application Number: US-201314095277-A
Country: US
Kind Code: B2

Title: Carrier aggregation using unlicensed frequency bands

Abstract:
Carrier aggregation using unlicensed frequency bands. A primary carrier for communication between a base station (BS) and a wireless user equipment (UE) device may be configured according to a first wireless communication technology. The primary carrier may be on a licensed frequency band. A secondary carrier for communication between the BS and the UE may also be configured according to a first wireless communication technology. The secondary carrier may be on an unlicensed frequency band. Channel conditions for each of multiple possible channels of the unlicensed frequency band may be assessed according to a second wireless communication technology as part of configuring the secondary carrier.

Claims:
What is claimed is: 
     
       1. A wireless user equipment (UE) device, comprising:
 a radio, comprising one or more antennas configured for wireless communication; and 
 a processing element operably coupled to the radio, 
 wherein the radio and the processing element are configured to:
 establish a primary carrier with a base station according to a cellular communication technology, wherein the primary carrier is on a licensed frequency band; 
 receive information indicating a plurality of channels on an unlicensed frequency band from the base station via the primary carrier; 
 determine whether the UE device is capable of communicating according to the cellular communication technology on each of the plurality of channels of the unlicensed frequency band; 
 transmit information indicating whether the UE device is capable of communicating according to the cellular communication technology on each of the plurality of channels of the unlicensed frequency band to the base station via the primary carrier, wherein the information indicates that the UE device is not capable of communicating according to the cellular communication technology for at least a first channel of the plurality of channels of the unlicensed frequency band, wherein the information is configured for use by the base station in selecting a channel on which to establish a secondary carrier; and 
 establish the secondary carrier with the base station according to the cellular communication technology, wherein the secondary carrier is on the unlicensed frequency band. 
 
 
     
     
       2. The UE device of  claim 1 , wherein the radio and the processing element are further configured to:
 monitor channel conditions of a channel on which the secondary carrier is established; and 
 transmit information regarding the channel conditions of the channel on which the secondary carrier is established to the base station. 
 
     
     
       3. The UE device of  claim 2 , wherein the radio and the processing element are further configured to:
 receive an indication to move the secondary carrier to a different channel on the unlicensed frequency band than the channel on which the secondary carrier is established; and 
 establish the secondary carrier on the different channel in response to the indication. 
 
     
     
       4. The UE device of  claim 1 , wherein the radio and the processing element are further configured to:
 receive control communications for both the primary carrier and the secondary carrier via the primary carrier. 
 
     
     
       5. The UE device of  claim 1 ,
 wherein the unlicensed frequency band is an industrial-scientific-medical (ISM) frequency band. 
 
     
     
       6. The UE device of  claim 1 , wherein the radio and the processing element are further configured to:
 transmit a contention control message according to a different wireless communication technology on the channel on which the secondary carrier is established prior to at least one communication using the secondary carrier. 
 
     
     
       7. A method, comprising:
 establishing a primary carrier between a base station and a mobile station according to a cellular communication technology, wherein the primary carrier is on a licensed frequency band; 
 establishing a secondary carrier between the base station and the mobile station according to the cellular communication technology, wherein the secondary carrier is on an unlicensed frequency band; 
 determining channel conditions of a first channel on which the secondary carrier is established; 
 in response to the channel conditions of the first channel falling below a desired level, performing handover from the first channel to a second channel of the secondary carrier. 
 
     
     
       8. The method of  claim 7 , wherein determining channel conditions of the secondary channel comprises periodically:
 monitoring channel conditions of the first channel; and 
 transmitting information regarding the channel conditions of the first channel to the base station. 
 
     
     
       9. The method of  claim 7 , wherein performing handover comprises:
 receiving an indication to move the secondary carrier to the second channel on the unlicensed frequency band; and 
 establishing the secondary carrier on the second channel in response to the indication. 
 
     
     
       10. The method of  claim 7 , wherein said determining channel conditions is performed by the mobile station. 
     
     
       11. The method of  claim 7 , wherein said determining channel conditions is performed by the base station. 
     
     
       12. The method of  claim 7 , further comprising:
 receiving control communications for both the primary carrier and the secondary carrier via the primary carrier. 
 
     
     
       13. The method device of  claim 7 , further comprising:
 transmitting a contention control message according to a different wireless communication technology on the first channel on which the secondary carrier is established prior to at least one communication using the secondary carrier. 
 
     
     
       14. An apparatus, comprising:
 one or more processing elements, wherein the one or more processing elements are configured to:
 establish a primary carrier between a base station and a mobile station according to a cellular communication technology, wherein the primary carrier is on a licensed frequency band; 
 establish a secondary carrier between the base station and the mobile station according to the cellular communication technology, wherein the secondary carrier is on an unlicensed frequency band; 
 determine channel conditions of a first channel on which the secondary carrier is established; 
 in response to the channel conditions of the first channel falling below a desired level, perform handover from the first channel to a second channel of the secondary carrier. 
 
 
     
     
       15. The apparatus of  claim 14 , wherein determining channel conditions of the secondary channel comprises periodically:
 monitoring channel conditions of the first channel; and 
 transmitting information regarding the channel conditions of the first channel to the base station. 
 
     
     
       16. The apparatus of  claim 14 , wherein performing handover comprises:
 receiving an indication to move the secondary carrier to the second channel on the unlicensed frequency band; and 
 establishing the secondary carrier on the second channel in response to the indication. 
 
     
     
       17. The apparatus of  claim 14 , wherein said determining channel conditions is performed by the mobile station. 
     
     
       18. The apparatus of  claim 14 , wherein said determining channel conditions is performed by the base station. 
     
     
       19. The apparatus of  claim 14 , wherein the one or more processing elements are further configured to:
 receive control communications for both the primary carrier and the secondary carrier via the primary carrier. 
 
     
     
       20. The apparatus of  claim 14 , wherein the one or more processing elements are further configured to:
 transmit a contention control message according to a different wireless communication technology on the first channel on which the secondary carrier is established prior to at least one communication using the secondary carrier.

Description:
FIELD 
     The present application relates to wireless devices, and more particularly to a system and method for wireless devices to perform wireless communication with hybrid carrier aggregation using licensed and unlicensed frequency bands. 
     DESCRIPTION OF THE RELATED ART 
     Wireless communication systems are rapidly growing in usage. Additionally, there exist numerous different wireless communication technologies and standards. Some examples of wireless communication standards include GSM, UMTS (WCDMA), LTE, LTE Advanced (LTE-A), 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), IEEE 802.11 (WLAN or Wi-Fi), IEEE 802.16 (WiMAX), Bluetooth, and others. 
     In some wireless communication systems, such as certain cellular communication networks, wireless communication is performed on frequency bands which have been licensed (e.g., by a cellular network provider). Additionally, in some wireless communication systems, such as Wi-Fi and Bluetooth wireless communication systems, wireless communication is performed on unlicensed frequency bands, such as the 2.4 GHz ISM frequency band. 
     SUMMARY 
     Embodiments are presented herein of methods for configuring wireless devices to perform wireless communication with hybrid carrier aggregation using licensed and unlicensed frequency bands, and of devices configured to implement the methods. 
     According to the techniques described herein, a wireless device may communicate with a base station according to a first wireless communication, such as LTE, to establish a primary carrier, which may be used for control communications, data communications, etc. The primary carrier may be established on a licensed frequency band. 
     Additionally, the wireless device may communicate with the base station according to the same wireless communication technology to establish a secondary carrier. The secondary carrier may be established on an unlicensed frequency band. The secondary carrier may be used for data communications, though control communications relating to the secondary carrier may be performed via the primary carrier. 
     Since the secondary carrier may be established on an unlicensed frequency band, the base station and the wireless device may take certain steps to avoid and/or deter interference. For example, the base station might assess channel conditions for each of multiple channels of the unlicensed frequency band according to a second wireless communication technology, such as Wi-Fi. The base station may then select a channel for the secondary carrier based on the channel condition assessments. 
     In some cases, one or both of the base station or the wireless device may additionally employ contention control techniques according to the second wireless technology when communicating on the secondary carrier. For example, Wi-Fi clear-to-send (CTS) messages might be transmitted prior to communicating on the secondary carrier in some instances. 
     The techniques described herein may be implemented in and/or used with a number of different types of devices, including but not limited to cellular phones, tablet computers, wearable computing devices, portable media players, and any of various other computing devices. 
     This Summary is intended to provide a brief overview of some of the subject matter described in this document. Accordingly, it will be appreciated that the above-described features are merely examples and should not be construed to narrow the scope or spirit of the subject matter described herein in any way. Other features, aspects, and advantages of the subject matter described herein will become apparent from the following Detailed Description, Figures, and Claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A better understanding of the present subject matter can be obtained when the following detailed description of the embodiments is considered in conjunction with the following drawings, in which: 
         FIG. 1  illustrates an exemplary (and simplified) wireless communication system; 
         FIG. 2  illustrates a base station (BS) in communication with a user equipment (UE) device; 
         FIG. 3  illustrates an exemplary block diagram of a UE; 
         FIG. 4  illustrates an exemplary block diagram of a BS; 
         FIG. 5  illustrates an exemplary carrier aggregation scheme; 
         FIG. 6  illustrates an exemplary cross-carrier scheduling scheme; and 
         FIG. 7  is a flowchart diagram illustrating an exemplary method for carrier aggregation using unlicensed frequency bands. 
     
    
    
     While the features described herein may be susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to be limiting to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the subject matter as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Terms 
     The following is a glossary of terms used in this disclosure: 
     Memory Medium—Any of various types of non-transitory memory devices or storage devices. The term “memory medium” is intended to include an installation medium, e.g., a CD-ROM, floppy disks, or tape device; a computer system memory or random access memory such as DRAM, DDR RAM, SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash, magnetic media, e.g., a hard drive, or optical storage; registers, or other similar types of memory elements, etc. The memory medium may include other types of non-transitory memory as well or combinations thereof. In addition, the memory medium may be located in a first computer system in which the programs are executed, or may be located in a second different computer system which connects to the first computer system over a network, such as the Internet. In the latter instance, the second computer system may provide program instructions to the first computer for execution. The term “memory medium” may include two or more memory mediums which may reside in different locations, e.g., in different computer systems that are connected over a network. The memory medium may store program instructions (e.g., embodied as computer programs) that may be executed by one or more processors. 
     Carrier Medium—a memory medium as described above, as well as a physical transmission medium, such as a bus, network, and/or other physical transmission medium that conveys signals such as electrical, electromagnetic, or digital signals. 
     Programmable Hardware Element—includes various hardware devices comprising multiple programmable function blocks connected via a programmable interconnect. Examples include FPGAs (Field Programmable Gate Arrays), PLDs (Programmable Logic Devices), FPOAs (Field Programmable Object Arrays), and CPLDs (Complex PLDs). The programmable function blocks may range from fine grained (combinatorial logic or look up tables) to coarse grained (arithmetic logic units or processor cores). A programmable hardware element may also be referred to as “reconfigurable logic”. 
     Computer System—any of various types of computing or processing systems, including a personal computer system (PC), mainframe computer system, workstation, network appliance, Internet appliance, personal digital assistant (PDA), television system, grid computing system, or other device or combinations of devices. In general, the term “computer system” can be broadly defined to encompass any device (or combination of devices) having at least one processor that executes instructions from a memory medium. 
     User Equipment (UE) (or “UE Device”)—any of various types of computer systems devices which are mobile or portable and which performs wireless communications. Examples of UE devices include mobile telephones or smart phones (e.g., iPhone™, Android™-based phones), portable gaming devices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™, iPhone™), laptops, PDAs, portable Internet devices, music players, data storage devices, or other handheld devices, etc. In general, the term “UE” or “UE device” can be broadly defined to encompass any electronic, computing, and/or telecommunications device (or combination of devices) which is easily transported by a user and capable of wireless communication. 
     Base Station—The term “Base Station” has the full breadth of its ordinary meaning, and at least includes a wireless communication station installed at a fixed location and used to communicate as part of a wireless telephone system or radio system. 
     Processing Element—refers to various elements or combinations of elements. Processing elements include, for example, circuits such as an ASIC (Application Specific Integrated Circuit), portions or circuits of individual processor cores, entire processor cores, individual processors, programmable hardware devices such as a field programmable gate array (FPGA), and/or larger portions of systems that include multiple processors. 
     Channel—a medium used to convey information from a sender (transmitter) to a receiver. It should be noted that since characteristics of the term “channel” may differ according to different wireless protocols, the term “channel” as used herein may be considered as being used in a manner that is consistent with the standard of the type of device with reference to which the term is used. In some standards, channel widths may be variable (e.g., depending on device capability, band conditions, etc.). For example, LTE may support scalable channel bandwidths from 1.4 MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide while Bluetooth channels may be 1 Mhz wide. Other protocols and standards may include different definitions of channels. Furthermore, some standards may define and use multiple types of channels, e.g., different channels for uplink or downlink and/or different channels for different uses such as data, control information, etc. 
     Automatically—refers to an action or operation performed by a computer system (e.g., software executed by the computer system) or device (e.g., circuitry, programmable hardware elements, ASICs, etc.), without user input directly specifying or performing the action or operation. Thus the term “automatically” is in contrast to an operation being manually performed or specified by the user, where the user provides input to directly perform the operation. An automatic procedure may be initiated by input provided by the user, but the subsequent actions that are performed “automatically” are not specified by the user, i.e., are not performed “manually”, where the user specifies each action to perform. For example, a user filling out an electronic form by selecting each field and providing input specifying information (e.g., by typing information, selecting check boxes, radio selections, etc.) is filling out the form manually, even though the computer system must update the form in response to the user actions. The form may be automatically filled out by the computer system where the computer system (e.g., software executing on the computer system) analyzes the fields of the form and fills in the form without any user input specifying the answers to the fields. As indicated above, the user may invoke the automatic filling of the form, but is not involved in the actual filling of the form (e.g., the user is not manually specifying answers to fields but rather they are being automatically completed). The present specification provides various examples of operations being automatically performed in response to actions the user has taken. 
       FIGS. 1 and 2 —Communication System 
       FIG. 1  illustrates an exemplary (and simplified) wireless communication system. It is noted that the system of  FIG. 1  is merely one example of a possible system, and embodiments of the invention may be implemented in any of various systems, as desired. 
     As shown, the exemplary wireless communication system includes a base station  102 A which communicates over a transmission medium with one or more user devices  106 A,  102 B, etc., through  106 N. Each of the user devices may be referred to herein as a “user equipment” (UE). Thus, the user devices  106  are referred to as UEs or UE devices. 
     The base station  102 A may be a base transceiver station (BTS) or cell site, and may include hardware that enables wireless communication with the UEs  106 A through  106 N. The base station  102 A may also be equipped to communicate with a network  100  (e.g., a core network of a cellular service provider, a telecommunication network such as a public switched telephone network (PSTN), and/or the Internet, among various possibilities). Thus, the base station  102 A may facilitate communication between the user devices and/or between the user devices and the network  100 . 
     The communication area (or coverage area) of the base station may be referred to as a “cell.” The base station  102 A and the UEs  106  may be configured to communicate over the transmission medium using any of various radio access technologies (RATs), also referred to as wireless communication technologies, or telecommunication standards, such as GSM, UMTS (WCDMA, TD-SCDMA), LTE, LTE-Advanced (LTE-A), 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), Wi-Fi, WiMAX etc. 
     Base station  102 A and other similar base stations (such as base stations  102 B . . .  102 N) operating according to the same or a different cellular communication standard may thus be provided as a network of cells, which may provide continuous or nearly continuous overlapping service to UEs  106 A-N and similar devices over a wide geographic area via one or more cellular communication standards. 
     Thus, while base station  102 A may act as a “serving cell” for UEs  106 A-N as illustrated in  FIG. 1 , each UE  106  may also be capable of receiving signals from (and possibly within communication range of) one or more other cells (which might be provided by base stations  102 B-N and/or any other base stations), which may be referred to as “neighboring cells”. Such cells may also be capable of facilitating communication between user devices and/or between user devices and the network  100 . Such cells may include “macro” cells, “micro” cells, “pico” cells, and/or cells which provide any of various other granularities of service area size. For example, base stations  102 A-B illustrated in  FIG. 1  might be macro cells, while base station  102 N might be a micro cell. Other configurations are also possible. 
     Note that a UE  106  may be capable of communicating using multiple wireless communication standards. For example, a UE  106  might be configured to communicate using two or more of GSM, UMTS, CDMA2000, WiMAX, LTE, LTE-A, WLAN, Bluetooth, one or more global navigational satellite systems (GNSS, e.g., GPS or GLONASS), one and/or more mobile television broadcasting standards (e.g., ATSC-M/H or DVB-H), etc. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible. 
       FIG. 2  illustrates user equipment  106  (e.g., one of the devices  106 A through  106 N) in communication with a base station  102  (e.g., one of the base stations  102 A through  102 N). The UE  106  may be a device with cellular communication capability such as a mobile phone, a hand-held device, a computer or a tablet, or virtually any type of wireless device. 
     The UE  106  may include a processor that is configured to execute program instructions stored in memory. The UE  106  may perform any of the method embodiments described herein by executing such stored instructions. Alternatively, or in addition, the UE  106  may include a programmable hardware element such as an FPGA (field-programmable gate array) that is configured to perform any of the method embodiments described herein, or any portion of any of the method embodiments described herein. 
     In some embodiments, the UE  106  may be configured to communicate using any of multiple radio access technologies/wireless communication protocols. For example, the UE  106  may be configured to communicate using two or more of GSM, UMTS, CDMA2000, LTE, LTE-A, WLAN/Wi-Fi, or GNSS. Other combinations of wireless communication technologies are also possible. 
     The UE  106  may include one or more antennas for communicating using one or more wireless communication protocols. In some embodiments, the UE  106  may share one or more parts of a receive and/or transmit chain between multiple wireless communication standards. The shared radio may include a single antenna, or may include multiple antennas (e.g., for MIMO) for performing wireless communications. Alternatively, the UE  106  may include separate transmit and/or receive chains (e.g., including separate antennas and other radio components) for each wireless communication protocol with which it is configured to communicate. As a further alternative, the UE  106  may include one or more radios which are shared between multiple wireless communication protocols, and one or more radios which are used exclusively by a single wireless communication protocol. Other configurations are also possible. 
       FIG. 3 —Exemplary Block Diagram of a UE 
       FIG. 3  illustrates an exemplary block diagram of a UE  106 . As shown, the UE  106  may include a system on chip (SOC)  300 , which may include portions for various purposes. For example, as shown, the SOC  300  may include processor(s)  302  which may execute program instructions for the UE  106  and display circuitry  304  which may perform graphics processing and provide display signals to the display  360 . The processor(s)  302  may also be coupled to memory management unit (MMU)  340 , which may be configured to receive addresses from the processor(s)  302  and translate those addresses to locations in memory (e.g., memory  306 , read only memory (ROM)  350 , NAND flash memory  310 ) and/or to other circuits or devices, such as the display circuitry  304 , wireless communication circuitry  330 , connector I/F  320 , and/or display  360 . The MMU  340  may be configured to perform memory protection and page table translation or set up. In some embodiments, the MMU  340  may be included as a portion of the processor(s)  302 . 
     As shown, the SOC  300  may be coupled to various other circuits of the UE  106 . For example, the UE  106  may include various types of memory (e.g., including NAND flash  310 ), a connector interface  320  (e.g., for coupling to a computer system, dock, charging station, etc.), the display  360 , and wireless communication circuitry (e.g., radio)  330  (e.g., for LTE, Wi-Fi, GPS, etc.). 
     The UE device  106  may include at least one antenna, and in some embodiments multiple antennas, for performing wireless communication with base stations and/or other devices. For example, the UE device  106  may use antenna  335  to perform the wireless communication. As noted above, the UE  106  may be configured to communicate wirelessly using multiple wireless communication standards in some embodiments. 
     As described further subsequently herein, the UE  106  may include hardware and software components for implementing features for carrier aggregation using both licensed and unlicensed frequency bands, such as those described herein with reference to, inter alia,  FIG. 7 . The processor  302  of the UE device  106  may be configured to implement part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). In other embodiments, processor  302  may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit). Alternatively (or in addition) the processor  302  of the UE device  106 , in conjunction with one or more of the other components  300 ,  304 ,  306 ,  310 ,  320 ,  330 ,  335 ,  340 ,  350 ,  360  may be configured to implement part or all of the features described herein, such as the features described herein with reference to, inter alia,  FIG. 7 . 
       FIG. 4 —Exemplary Block Diagram of a Base Station 
       FIG. 4  illustrates an exemplary block diagram of a base station  102 . It is noted that the base station of  FIG. 4  is merely one example of a possible base station. As shown, the base station  102  may include processor(s)  404  which may execute program instructions for the base station  102 . The processor(s)  404  may also be coupled to memory management unit (MMU)  440 , which may be configured to receive addresses from the processor(s)  404  and translate those addresses to locations in memory (e.g., memory  460  and read only memory (ROM)  450 ) or to other circuits or devices. 
     The base station  102  may include at least one network port  470 . The network port  470  may be configured to couple to a telephone network and provide a plurality of devices, such as UE devices  106 , access to the telephone network as described above in  FIGS. 1 and 2 . 
     The network port  470  (or an additional network port) may also or alternatively be configured to couple to a cellular network, e.g., a core network of a cellular service provider. The core network may provide mobility related services and/or other services to a plurality of devices, such as UE devices  106 . In some cases, the network port  470  may couple to a telephone network via the core network, and/or the core network may provide a telephone network (e.g., among other UE devices serviced by the cellular service provider). 
     The base station  102  may include at least one antenna  434 , and possibly multiple antennas. The at least one antenna  434  may be configured to operate as a wireless transceiver and may be further configured to communicate with UE devices  106  via radio  430 . The antenna  434  communicates with the radio  430  via communication chain  432 . Communication chain  432  may be a receive chain, a transmit chain or both. The radio  430  may be configured to communicate via various wireless telecommunication standards, including, but not limited to, LTE, LTE-A, UMTS, CDMA2000, Wi-Fi, etc. 
     The BS  102  may be configured to communicate wirelessly using multiple wireless communication standards. In some instances, the base station  102  may include multiple radios, which may enable the base station  102  to communicate according to multiple wireless communication technologies. For example, as one possibility, the base station  102  may include an LTE radio for performing communication according to LTE as well as a Wi-Fi radio for performing communication according to Wi-Fi. In such a case, the base station  102  may be capable of operating as both an LTE base station and a Wi-Fi access point. As another possibility, the base station  102  may include a multi-mode radio which is capable of performing communications according to any of multiple wireless communication technologies (e.g., LTE and Wi-Fi). 
     Such capabilities may be particularly useful for managing interference and coordinating communication on unlicensed frequency bands, e.g., on which wireless communication according to multiple wireless communication technologies may be possible (and possibly even common), which the BS  102  may be configured to do. For example, as described further subsequently herein, the BS  102  may include hardware and software components for implementing features for carrier aggregation using both licensed and unlicensed frequency bands, such as those described herein with reference to, inter alia,  FIG. 7 . The processor  404  of the base station  102  may be configured to implement part or all of the methods described herein, e.g., by executing program instructions stored on a memory medium (e.g., a non-transitory computer-readable memory medium). Alternatively, the processor  404  may be configured as a programmable hardware element, such as an FPGA (Field Programmable Gate Array), or as an ASIC (Application Specific Integrated Circuit), or a combination thereof. Alternatively (or in addition) the processor  404  of the BS  102 , in conjunction with one or more of the other components  430 ,  432 ,  434 ,  440 ,  450 ,  460 ,  470  may be configured to implement part or all of the features described herein, such as the features described herein with reference to, inter alia,  FIG. 7 . 
       FIG. 5 —Carrier Aggregation 
     Carrier aggregation is a scheme in which multiple carriers (e.g., frequency channels) may be used for wireless communication with a UE according to a wireless communication technology.  FIG. 5  illustrates one exemplary carrier aggregation scheme (e.g., which may be used in accordance with the LTE radio access technology) which may be used in accordance with other aspects of this disclosure, such as with respect to the method of  FIG. 7 . 
     In the illustrated scheme, up to five component carriers (carriers  504 ,  506 ,  508 ,  510 ,  512 ) may be aggregated for a single user device (such one of the UEs  106  illustrated in and described with respect to  FIGS. 1-3 ). Each component carrier may use a channel width of up to 20 MHz. As one possibility, each component carrier may be an LTE release  8  carrier. Thus, according to the exemplary scheme, a UE may be allocated up to 100 MHz of bandwidth. In many instances, such a carrier aggregation scheme may enable a UE participating in it with greater throughput than without such a scheme. 
     In many cases, component carriers may utilize adjacent frequency channels. However, it should be noted that it is also possible to implement carrier aggregation utilizing non-continuous frequency channels, potentially including non-continuous frequency channels within the same frequency band, and/or frequency channels within different frequency bands. For example, according to the method of  FIG. 7 , it may be possible to implement carrier aggregation using a frequency channel in a licensed frequency band as one component carrier, and a frequency channel in an unlicensed frequency band as another component carrier. 
     It should be noted that while the exemplary scheme illustrated in  FIG. 5  and the associated description are provided by way of example as one possible manner of implementing carrier aggregation, they are not intended to be limiting to the disclosure as a whole. Numerous alternatives to and variations of the details thereof are possible and should be considered within the scope of the present disclosure. For example: carrier aggregation schemes may be implemented in conjunction with other wireless communication technologies; carriers according to other LTE releases or other radio access technologies altogether may be used; carriers having different channel widths may be used; different numbers of component carriers may be supported; and/or any of numerous other alternatives to and variations of the illustrated scheme are also possible. 
       FIG. 6 —Cross-Carrier Scheduling 
     For systems which implement carrier aggregation, various control schemes/mechanisms are possible. As one possibility, an independent cell may be implemented on each component carrier, for example by providing a control channel with data scheduling and other control features for each cell on the component carrier for that cell. As another possibility, some or all control functions may be centralized. For example, a “primary cell” might be implemented on one component carrier, while “secondary cells” might be implemented on any additional component carriers, such that some or all control information for the secondary cells is communicated by way of the primary cell. 
     Such a scheme may be referred to as “cross-carrier scheduling”, and  FIG. 6  illustrates one such exemplary scheme (e.g., which may be used in accordance with the LTE radio access technology). It should be noted that while the exemplary scheme illustrated in  FIG. 6  and the associated description are provided by way of example as one possible manner of implementing a cross-carrier scheduling mechanism, they are not intended to be limiting to the disclosure as a whole. Numerous alternatives to and variations of these exemplary details are possible and should be considered within the scope of the present disclosure. 
     As shown, in the exemplary scheme a user device (e.g., a UE  106  such as illustrated in and described with respect to  FIGS. 1-3 ) may have three active carriers as part of its connection to a network (e.g., by way of one or more base stations  102  such as illustrated in and described with respect to  FIGS. 1-2 and 4 ), which may be implemented as a primary cell  602  and two secondary cells  604 ,  606 . The network may provide control data  608  (e.g., for scheduling user data communications, performing mobility related functions, etc.) for all three cells by way of a control channel of the primary cell  602 . For example, the control data  608  may be communicated by way of a physical downlink control channel (PDCCH) of the primary cell  602 . 
     The network may provide user data  610  (e.g., application data for networking applications such as web browser applications, email applications voice call applications, video chat applications, game applications, etc.) to the UE  106  on any or all of the cells  602 ,  604 ,  606 . For example, various portions of the user data  610  may be communicated by way of a physical downlink shared channel (PDSCH) of each of the primary cell  602  and the secondary cells  604 ,  606 . 
     Thus, cross-carrier scheduling may be used in conjunction with carrier aggregation to centralize (at least a portion of) control communications on one cell. This technique may be used in many instances for infrastructure mode communications between a UE and a network, such as illustrated in the exemplary scheme of  FIG. 6 . Such a technique may be particularly useful if different component carriers are known and/or expected to have different interference levels, since in such a case the carrier having the lowest interference level may advantageously be used for high priority control data. Such a situation may be the case, for example, if, as in the method of  FIG. 7 , one component carrier is on a licensed frequency band for which the potential for interference is substantially limited to that caused by network controlled wireless communication, while another component carrier is on an unlicensed frequency band which may be subject to interference caused by wireless communication which is not under network control. 
       FIG. 7 —Communication Flow Diagram 
       FIG. 7  is a communication/signal flow diagram illustrating a scheme for hybrid carrier aggregation using both licensed and unlicensed frequency bands. The scheme shown in  FIG. 7  may be used in conjunction with any of the computer systems or devices shown in the above Figures, among other devices. As shown, according to the scheme a BS  102  (e.g., such as illustrated in and described with respect to  FIGS. 1-2 and 4 ) may provide a UE  106  (e.g., such as illustrated in and described with respect to  FIGS. 1-3 ) with a carrier aggregation communication link having component carriers in both licensed and unlicensed frequency bands. 
     In various embodiments, some of the elements of the scheme shown may be performed concurrently, in a different order than shown, or may be omitted. Additional elements may also be performed as desired. As shown, the scheme may operate as follows. 
     In  702 , the BS  102  may establish (e.g., configure) a primary carrier (or “primary cell”) with the UE  106 . The primary carrier may be established according to a first wireless communication technology (or “radio access technology” or “RAT”), such as LTE. The primary carrier may be established on a particular (“first”) channel (e.g., a frequency channel). 
     The first channel may be a channel be in a licensed frequency band, which may also be referred to herein as a “first frequency band”. For example, a cellular network provider may have licensed a particular frequency band (possibly specifically for use in conjunction with a particular radio access technology, such as LTE-A, LTE, WCDMA, CDMA2000, GSM, etc.), and may provide a cellular network which operates primarily within that licensed frequency band. Such a licensed frequency band may be subject to less external interference than an unlicensed frequency band. For example, an unlicensed frequency band might be subject to interference from other wireless communication technologies and/or from other cellular network operators utilizing a similar or the same wireless communication technology in the unlicensed frequency band, whereas a licensed frequency band may not be subject to such external interference sources, e.g., if the licensed frequency band is licensed for the exclusive use of one particular cellular network provider. 
     The primary carrier may provide the UE  106  with an infrastructure mode type communication link to a cellular network. Thus, the primary carrier may provide a connection to a core network, e.g., of a cellular service provider, with which a user of the UE  106  may have a subscription and/or other agreement to provide cellular service. The cellular network may thus provide connectivity between the user device and various services and/or devices coupled to the cellular network, such as other user devices, a public switched telephone network, the Internet, various cloud-based services, etc. The primary carrier may be used for control communications between the UE  106  and the BS  102 , and may also be used for data (e.g., user data) communications. 
     Note that as part of such a cellular network, the base station  102  may operate in conjunction with numerous other base stations (which may provide other cells) and other network hardware and software to provide continuous (or nearly continuous) overlapping wireless service over a wide geographic area. At least in some instances, the UE  106  may select a cell with the BS  102  to establish as the primary cell from among multiple cells within wireless communication range of the UE  106 , which may be provided by nearby base stations. For example, the UE  106  may be capable of discovering, detecting signals from, and possibly communicating with some or all of multiple neighboring cells, e.g., depending on signal strength/quality, permission, technological interoperability, etc. The primary cell may be selected and configured/established on the basis of one or more signal strength and/or signal quality measurements of the primary cell and/or other nearby cells, among other possible criteria (e.g., wireless traffic congestion of the cell(s), operator of the cell(s), wireless technology according to which the cell(s) operate, etc.). 
     Note further that cell selection may be an initial cell selection, e.g., upon powering on the UE  106  (or possibly after powering on a radio of the UE  106 , e.g., upon exiting a limited-operation or “airplane mode”), according to some embodiments. Alternatively, the cell selection may be part of a cell re-selection procedure. For example, the UE  106  might perform a cell re-selection procedure to select a new cell with better signal strength and/or quality as a primary cell based on experiencing degraded signal strength and/or quality on a previous primary cell, e.g., as a result of moving from a service area of the previous primary cell to a service area of the new primary cell. 
     In  704 , the BS  102  may scan channels of an unlicensed (“second”) frequency band, such as an industrial-scientific-medical (ISM) frequency band, e.g., for interference. As previously noted, since unlicensed frequency bands may be subject to interference from other wireless communication (e.g., potentially from one or more other wireless communication technologies) which is not under network control, it may be desirable to determine how much interference is currently present on each of the channels in the unlicensed frequency band prior to selecting one for use as a secondary carrier. 
     In particular, at least in some instances it may be desirable to check for Wi-Fi interference, e.g., if the unlicensed frequency band is one in which Wi-Fi communication is known to be performed. Thus the BS  102  may scan one or more Wi-Fi channels on the unlicensed frequency band. The BS  102  may be equipped with (or coupled to and in control of) Wi-Fi communication circuitry (e.g., may be configured to act as a Wi-Fi access point, or may be coupled to and control a Wi-Fi access point) specifically for such a purpose (and/or for other purposes), if desired. Scanning the Wi-Fi channels may include measuring any of various channel condition metrics and/or metrics which may be used to gauge or infer interference levels, such as RSSI. As one possibility, the BS  102  may perform power spectrum density detection on such an unlicensed frequency band. 
     Based on scanning the Wi-Fi channels, the BS  102  may select one or more channels (e.g., Wi-Fi channels, or channels according to the first wireless communication technology (such as LTE channels) which may correspond/overlap in frequency with one or more of the Wi-Fi channels) in the unlicensed frequency band as potential channels on which to establish a secondary carrier. The selected channel(s) may be those on which Wi-Fi interference has been determined to be less likely and/or prevalent, such as channels for which RSSI are below a desired threshold. 
     Having selected one or more channels as potential secondary carriers, the BS  102  may provide an indication of such channels to the UE  106 . For example, the BS  102  may generate and provide a list of potential channels in the unlicensed frequency band to the UE  106  in a configuration message (e.g., an RRC configuration object) via the primary cell. The UE  106  may store such a list of potential channels and configure each channel on the list as a potential carrier, though each remain ‘inactive’ and unused as an actual carrier until more explicitly activated. 
     In  708 , the UE  106  may additionally provide feedback to the BS  102  (e.g., via the primary cell) with respect to such a list of potential channels in the unlicensed frequency band. For example, the UE  106  may perform one or more measurements (e.g., on interference/signal strength/RSSI scans/any of various other channel condition metrics) on some or all of the potential channels to determine channel conditions for those channels local to the UE  106 , e.g., to confirm that those channels are also relatively free of interference in the vicinity of the UE  106 . As another example, the UE  106  may have limits to its wireless communication capabilities, as a result of which it may not be possible to perform communications according to the first wireless communication technology on a particular frequency band, potentially including one or more of the potential channels indicated by the BS  102 . Thus, the UE  106  might provide channel condition information, a pruned (or unpruned) list of supported channels, a list of unsupported channels, and/or any of various other forms of feedback to the BS  102  with respect to the list of potential channels in the unlicensed frequency band. 
     Once any scanning/channel measurements have been performed by the BS  102 , and possibly based additionally on any feedback received from the UE  106 , then the BS  102  may select a (“second”) channel on which to establish the secondary carrier. The selection may be based on one or more of the scanning/channel measurements, any feedback received from the UE  106 , and/or network resource allocation considerations (e.g., known loading/use of network controlled communications, resource availability, etc.), among various possibilities. 
     In  710 , a secondary carrier may be established on the unlicensed frequency band. The secondary carrier may be established on the selected “second” channel. The BS  102  may activate the secondary carrier by providing an indication the UE  106  to establish the secondary carrier on the second channel, e.g., via a configuration message (such as a “Scell Add” configuration message in LTE) transmitted on the primary carrier. Note that the secondary carrier may, like the primary carrier, be established according to the first wireless communication technology. 
     In some instances, the cellular network may utilize cross-carrier scheduling to schedule/allocate secondary cell resources to the UE  106 . For example, the BS  102  may provide scheduling information (e.g., uplink and/or downlink grants) for scheduling secondary cell resources the UE  106  via the primary carrier. Using cross-carrier scheduling may enable the network to keep control communications on the licensed frequency band, which as previously noted with respect to  FIG. 6 , may be subject to less (or at least less external) interference than the unlicensed frequency band. 
     In  712 , one or the other (or possibly both) of the BS  102  or the UE  106  may transmit a contention control message on the second channel (or on a channel of the second wireless communication technology corresponding in frequency to the second channel). The contention control message may be transmitted prior to at least one communication between the UE  106  and the BS  102  via the secondary carrier. The contention control message may be in a format according to a second wireless communication technology, and may be transmitted using signals according to the second wireless communication technology. For example, the contention control message may be a Wi-Fi clear-to-send (CTS) message. 
     One or both of the BS  102  and the UE  106  may be equipped with (or communicatively coupled with) wireless communication circuitry capable of communicating according to the second wireless communication technology. For example, as previously noted, the BS  102  may be equipped with Wi-Fi communication circuitry; additionally or alternatively, the UE  106  may be equipped with Wi-Fi communication circuitry. 
     Use of such a contention control message on a channel in an unlicensed frequency band may deter other devices which might otherwise communicate on that channel (and thereby cause interference to communication between the UE  106  and the BS  102 ) from communicating for a period of time. For example, the contention control message may include a duration value which may indicate to devices capable of operating according to the second wireless communication technology of a period of time for which the medium (e.g., channel) may be occupied. Having such knowledge as a result of the contention control message, such devices may refrain from communicating (e.g., according to the second wireless communication technology) on that particular channel until after the specified period of time has passed. 
     In  714 , the UE  106  and the BS  102  may communicate via the secondary carrier. This may include transmission of uplink data (i.e., from the UE  106  to the BS  102 ) and/or downlink data (i.e., from the BS  102  to the UE  106 ), and may be performed according to scheduling configured by the BS  102  and communicated to the UE  106  via the primary carrier (i.e., as part of cross-carrier scheduling, such as previously described herein). 
     Note that once the secondary carrier is active the UE  106  and/or the BS  102  may monitor one or more link quality metrics (e.g., signal strength and/or quality metrics such as RSRP and/or RSRQ, packet loss rate, etc.) of the secondary carrier. Results of such monitoring by the UE  106  may be reported to the BS  102  (e.g., in a link quality report) via the primary cell. Note that such monitoring and reporting may be controlled/configured by the BS  102  (e.g., using indications/requests transmitted via the primary cell) and/or may be performed by the UE  106  in a manner controlled by the UE  106 . Note additionally that such monitoring and reporting may be time based (e.g., periodically performed at certain preconfigured or dynamically configured intervals), event based (e.g., activated by certain events), or a combination of time based and event based. The BS  102  may additionally monitor (e.g., re-assess) the remainder of the unlicensed frequency band (or some portion thereof) occasionally (e.g., periodically or aperiodically). 
     Based at least in part on the link quality of the secondary carrier (e.g., as measured/reported by the UE  106  and/or as measured by the BS  102 ) and/or re-assessment of channel conditions of other channels of the unlicensed frequency band, the BS  102  may determine whether or not to initiate handover from the secondary carrier. As some point, the link quality of the second channel may fall below a desired level. In such a case, the BS  102  may determine to handover the secondary carrier to a different channel, and may select to which channel the secondary carrier is handed over. Determining that the link quality of the second channel has deteriorated may be performed in any of a variety of ways; as one example, if any monitored link quality metrics fall below a pre-configured threshold, this may be consideration that link quality of the second channel has deteriorated to an undesirable level. In such a situation, the BS  102  may be determine to switch or hop the secondary carrier to another channel, which may or may not be on the unlicensed frequency band. The BS  102  may then provide a handover command (which may simply include an “Scell Drop” command for the second channel and an “Scell Add” command for the new channel of the secondary carrier, e.g., if the new channel has already been configured as one of the channels in the list of potential channels, or may be performed in any of various other ways) via the primary cell to the UE  106 . 
     Once the UE  106  has received an indication to perform handover, with details of the handover, the UE  106  may perform handover (e.g., according to the provided details in the indication). After handover, the BS  102  and the UE  106  may continue to communicate on the secondary carrier, but the secondary carrier may be established on a different channel than previously. 
     Thus, according to the scheme of  FIG. 7 , a wireless device may be able to communicate with a cellular network on a carrier aggregation communication link for which at least one of the component carriers is on a licensed frequency band and at least one of the component carriers is on an unlicensed frequency band. This may potentially expand the throughput available to the wireless device, as use may be made of underutilized/available unlicensed portions of the RF spectrum in addition to frequency bands licensed by the cellular service provider of the wireless device. 
     Note additionally that while the method of  FIG. 7  describes steps for establishing one component carrier on a licensed frequency band and one component carrier on an unlicensed frequency band, the method may be expanded and/or repeated as desired to provide a wireless device with a cellular communication link having any number of component carriers. For example, a cellular communication link having two or more component carriers in the licensed frequency band, two or more component carriers in the unlicensed frequency band, component carriers in more than two different frequency bands, and/or any of various other configurations are possible. 
     Embodiments of the present disclosure may be realized in any of various forms. For example some embodiments may be realized as a computer-implemented method, a computer-readable memory medium, or a computer system. Other embodiments may be realized using one or more custom-designed hardware devices such as ASICs. Still other embodiments may be realized using one or more programmable hardware elements such as FPGAs. 
     In some embodiments, a non-transitory computer-readable memory medium may be configured so that it stores program instructions and/or data, where the program instructions, if executed by a computer system, cause the computer system to perform a method, e.g., any of a method embodiments described herein, or, any combination of the method embodiments described herein, or, any subset of any of the method embodiments described herein, or, any combination of such subsets. 
     In some embodiments, a device (e.g., a UE  106 ) may be configured to include a processor (or a set of processors) and a memory medium, where the memory medium stores program instructions, where the processor is configured to read and execute the program instructions from the memory medium, where the program instructions are executable to implement any of the various method embodiments described herein (or, any combination of the method embodiments described herein, or, any subset of any of the method embodiments described herein, or, any combination of such subsets). The device may be realized in any of various forms. 
     Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications.

Metadata:
Filing Date: 20131203
Publication Date: 20170124
Grant Date: 20170124
Priority Date: 20131203
Inventors: TABET TARIK
ZHANG DAWEI
ZHAO WEN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04L5/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/001", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/0453", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W16/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W16/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W72/0453", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W72/542", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W72/542", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W72/085", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04W16/14", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W72/0453", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L5/001", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 51842847