Abstract:
Apparatus having corresponding methods and computer-readable media comprise: a first transceiver comprising a controller configured to select one of a plurality of frequency regions, and a transmitter configured to transmit, according to a first protocol, first wireless signals in the one of the plurality of the frequency regions selected by the controller, wherein each frequency region is characterized by a respective type of unwanted interference generated responsive to the transmitter transmitting the first wireless signals in the respective frequency region; an arbiter configured to select one or more frequency channels based on the one of the plurality of the frequency regions selected by the controller; and a second transceiver configured to transceive, according to a second protocol, second wireless signals only in the one or more frequency channels selected by the arbiter.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This disclosure claims the benefit of U.S. Provisional Patent Application Ser. No. 61/534,675, filed on Sep. 14, 2011, entitled “Frequency Operation Indication for In-device Co-existence Interference Avoidance,” the disclosure thereof incorporated by reference herein in its entirety. 
    
    
     FIELD 
     The present disclosure relates generally to the field of wireless communication. More particularly, the present disclosure relates to avoiding interference between different wireless communication technologies that use adjacent or overlapping frequency bands. 
     BACKGROUND 
     The popularity of multiple wireless communication technologies for handheld platforms has created a need to integrate wireless communication technologies on a single wireless communication device. However, the frequency bands of some of these technologies are close enough to result in interference. For example, the unlicensed 2.4 GHz Industrial, Scientific and Medical (ISM) frequency band is adjacent to some of the bands used by Mobile Wireless Standards (MWS) technologies to result in adjacent channel interference. In many electronic devices such as smartphones, both ISM and MWS technologies are implemented in the same device. For example, a smartphone may employ LTE (Long Term Evolution) for phone calls, WiFi for local area networking, and Bluetooth for headsets. LTE transmissions from the smartphone will cause adjacent channel interference with incoming Bluetooth and WiFi signals. Similarly, Bluetooth and WiFi transmissions from the smartphone will cause adjacent channel interference with incoming LTE signals. This adjacent channel interference can significantly degrade performance not only at the smartphone, but also at connected MWS base stations. 
     SUMMARY 
     In general, in one aspect, an embodiment features an apparatus comprising: a first transceiver comprising a controller configured to select one of a plurality of frequency regions, and a transmitter configured to transmit, according to a first protocol, first wireless signals in the one of the plurality of the frequency regions selected by the controller, wherein each frequency region is characterized by a respective type of unwanted interference generated responsive to the transmitter transmitting the first wireless signals in the respective frequency region; an arbiter configured to select one or more frequency channels based on the one of the plurality of the frequency regions selected by the controller; and a second transceiver configured to transceive, according to a second protocol, second wireless signals only in the one or more frequency channels selected by the arbiter. 
     Embodiments of the apparatus can include one or more of the following features. In some embodiments, the first protocol is a Mobile Wireless Standards (MWS) protocol; and the second protocol is an Industrial, Scientific and Medical (ISM) band protocol. In some embodiments, the first protocol is an Industrial, Scientific and Medical (ISM) band protocol; and the second protocol is a Mobile Wireless Standards (MWS) protocol. In some embodiments, each of the first protocol and the second protocol is an Industrial, Scientific and Medical (ISM) band protocol. In some embodiments, the controller is further configured to provide an information signal, wherein the information signal indicates the one of the plurality of the frequency regions selected by the controller; and the arbiter is further configured to select the one or more frequency channels based on the information signal provided by the controller. In some embodiments, the types of unwanted interference comprise: spurious emissions; and out-of-band emissions. Some embodiments comprise one or more integrated circuits comprising the apparatus. Some embodiments comprise an electronic communication device comprising the apparatus. 
     In general, in one aspect, an embodiment features a method for an electronic device, the method comprising: selecting one of a plurality of frequency regions, wherein each frequency region is characterized by a respective type of unwanted interference generated responsive to the electronic device transmitting first wireless signals in the respective frequency region; transmitting, according to a first protocol, the first wireless signals in the one of the plurality of the frequency regions; selecting one or more frequency channels based on the one of the plurality of the frequency regions selected by the controller; and transceiving, according to a second protocol, second wireless signals only in the one or more frequency channels. 
     Embodiments of the method can include one or more of the following features. In some embodiments, the first protocol is a Mobile Wireless Standards (MWS) protocol; and the second protocol is an Industrial, Scientific and Medical (ISM) band protocol. In some embodiments, the first protocol is an Industrial, Scientific and Medical (ISM) band protocol; and the second protocol is a Mobile Wireless Standards (MWS) protocol. In some embodiments, each of the first protocol and the second protocol is an Industrial, Scientific and Medical (ISM) band protocol. Some embodiments comprise providing an information signal, wherein the information signal indicates the one of the plurality of the frequency regions; and selecting the one or more frequency channels based on the information signal. In some embodiments, the types of unwanted interference comprise: spurious emissions; and out-of-band emissions. 
     In general, in one aspect, an embodiment features computer-readable media embodying instructions executable by a computer in an electronic device to perform functions comprising: selecting one of a plurality of frequency regions, wherein each frequency region is characterized by a respective type of unwanted interference generated responsive to the electronic device transmitting first wireless signals in the respective frequency region; transmitting, according to a first protocol, the first wireless signals in the one of the plurality of the frequency regions; selecting one or more frequency channels based on the one of the plurality of the frequency regions selected by the controller; and transceiving, according to a second protocol, second wireless signals only in the one or more frequency channels. 
     Embodiments of the computer-readable media can include one or more of the following features. In some embodiments, the first protocol is a Mobile Wireless Standards (MWS) protocol; and the second protocol is an Industrial, Scientific and Medical (ISM) band protocol. In some embodiments, the first protocol is an Industrial, Scientific and Medical (ISM) band protocol; and the second protocol is a Mobile Wireless Standards (MWS) protocol. In some embodiments, each of the first protocol and the second protocol is an Industrial, Scientific and Medical (ISM) band protocol. In some embodiments, the functions further comprise: providing an information signal, wherein the information signal indicates the one of the plurality of the frequency regions; and selecting the one or more frequency channels based on the information signal. In some embodiments, the types of unwanted interference comprise: spurious emissions; and out-of-band emissions. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  shows elements of a communication system according to one embodiment. 
         FIG. 2  graphically illustrates the selection of frequency regions according to type of unwanted interference. 
         FIG. 3  shows a process for the user equipment of  FIG. 1  according to an embodiment where the arbiter assigns WiFi channels to the WiFi MAC based on the LTE channels used by the LTE device. 
         FIG. 4  shows a process for the user equipment of  FIG. 1  according to an embodiment where the arbiter assigns LTE channels to the LTE device based on the WiFi channels use by the WiFi MAC. 
     
    
    
     The leading digit(s) of each reference numeral used in this specification indicates the number of the drawing in which the reference numeral first appears. 
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure provide coexistence among multiple wireless communication technologies based on the frequency regions used by one or more of the wireless signals, where each frequency region is characterized by a respective type of unwanted interference generated by transmitting wireless signals in the respective frequency region. In some cases, the wireless communication technologies use adjacent frequency bands, and so cause adjacent channel interference. For example, some bands used by Mobile Wireless Standards (MWS) technologies are adjacent to the Industrial, Scientific and Medical (ISM) frequency band. In other cases, the interference results from wireless communication technologies using frequency bands that partially overlap or fully overlap. For example, both WiFi and Bluetooth use the ISM frequency band. 
       FIG. 1  shows elements of a communication system  100  according to one embodiment. Although in the described embodiments the elements of the communication system  100  are presented in one arrangement, other embodiments may feature other arrangements. For example, elements of the communication system  100  can be implemented in hardware, software, or combinations thereof. 
     Referring to  FIG. 1 , the communication system  100  includes a user equipment (UE)  102  capable of communications using multiple wireless technologies. The user equipment  102  can be implemented as any sort of electronic device capable of performing the functions described herein. For example, the user equipment  102  can be implemented as a smartphone, tablet computer, or the like. Elements of user equipment  102  can be implemented as one or more integrated circuits. 
     The user equipment  102  includes multiple transceivers employing different wireless technologies. In the example of  FIG. 1 , the transceivers include a Mobile Wireless Standards (MWS) transceiver and an Industrial, Scientific and Medical (ISM) band transceiver. In other embodiments, other numbers of transceivers and other combinations of wireless technologies can be employed instead. For example, the MWS transceivers can include Long Term Evolution (LTE) transceivers, Worldwide Interoperability for Microwave Access (WiMAX) transceivers, and the like, and the ISM band transceivers can include WiFi transceivers, Bluetooth transceivers, ZigBee transceivers, and the like. The transceivers can include two MWS transceivers or two ISM transceivers. The ISM band equipment can also include receive-only devices such as global positioning system (GPS) receivers, frequency modulation (FM) radio receivers, and the like. 
     In the example of  FIG. 1 , the transceivers include a WiFi media access controller (MAC)  104  and an LTE device  108 . Each transceiver communicates using one or more respective antennas. In particular, the WiFi MAC  104  uses one or more antennas  110 , and the LTE device  108  uses one or more antennas  114 . In some embodiments, one or more of the antennas  110 ,  114  can be combined. 
     The WiFi MAC  104  includes a receiver (WiFi Rx)  116 , a transmitter (WiFi Tx)  118 , and a WiFi controller  106 . The LTE device  108  includes a receiver (LTE Rx)  120 , a transmitter (LTE Tx)  122 , and an LTE controller  112 . The WiFi MAC  104  uses antenna  110  to transmit and receive wireless WiFi protocol signals  124  (also referred to herein as WiFi signals  124 ). The LIE device  108  uses antenna  114  to transmit and receive wireless LTE protocol signals  126  (also referred to herein as LTE signals  126 ). 
     The user equipment  102  also includes an arbiter  128 . The arbiter  128 , the LTE controller  112 , and the WiFi controller  106  can be implemented as one or more processors. Processors according to various embodiments can be fabricated as one or more integrated circuits. The arbiter  128  includes a channel map  138 . The channel map  138  can be stored in an internal memory of the arbiter  128 , in a memory external to the arbiter  128 , or the like. The arbiter  128  receives information signals  130 ,  132  from the transceivers  104 ,  108 , and provides control signals  134 ,  136  to the transceivers  104 ,  108 . The arbiter  128  receives the information signals  130  from the WiFi MAC  104 , and provides the control signals  134  to the WiFi MAC  104 . The arbiter  128  receives the information signals  132  from the LTE device  108 , and provides the control signals  136  to the LTE device  108 . In some embodiments, not all of the information signals  130 ,  132  and control signals  134 ,  136  are used. 
     The information signals  130 ,  132  include indications of the frequency regions used by the wireless signals  124 ,  126 , respectively. The indications of the frequency regions used by the wireless signals  124 ,  126  can include indications of the frequency regions used by the wireless signals  124 ,  126  received by the receivers  116 ,  120 , indications of the frequency regions used by the wireless signals  124 ,  126  employed by the transmitters  118 ,  122  to transmit the wireless signals  124 ,  126 , and the like. The frequency regions can include present frequency regions, as well as planned future frequency regions. 
     In conventional approaches, the indicated frequency regions are selected without regard to the type of unwanted interference produced by transmitting wireless signals in the frequency regions. However, different types of unwanted interference generated by one transceiver in a multi-transceiver device affect channels of the other receiver in the multi-transceiver device to different degrees. The present disclosure considers two types of unwanted interference: spurious emission and out-of-band emission. However, it will be understood that the techniques described herein are easily extended to other types of unwanted interference. 
     Spurious emission and out-of-band emission are defined with reference to the frequency channel in which the desired signal is transmitted. Out-of-band emission is emission on frequencies immediately outside the channel bandwidth which results from the modulation process, but excludes spurious emissions. Spurious emission is emission on frequencies which are outside the channel bandwidth, but excludes out-of-band emissions. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and frequency conversion products. 
     According to the described embodiments, the frequency regions of a transceiver are selected according to the type of unwanted interference generated by transmission of wireless signals in the channels.  FIG. 2  illustrates this selection graphically for a 20 MHz LTE channel  202 . Referring to  FIG. 2 , the LTE channel  202  is divided into two regions: a center region (region 0) and an edge region (region 1). The center region 0 is more likely allocated for a data channel, while the edge region 1 is more likely allocated for a control channel, such as a Physical Uplink Control Channel (PUCCH). In LTE release 8 and 9, the PUCCH control channel and data channel won&#39;t be transmitted at the same time. The LTE data channel generally transports more data, and so is generally allocated more LTE uplink resource blocks than the LIE control channel. For example, the LTE control channel is generally allocated less than 6 resource blocks, while the LTE data channel is generally allocated more than 10 resource blocks when the wider LTE bandwidth is allocated, such as 10 MHz. As a result, the center region 0 is characterized by out-of-band emissions, while the edge region 1 is characterized by spurious emission. 
     The described embodiments employ this difference in the selection of channels available to the co-located WiFi MAC  104 . In one embodiment, information signals  132  inform the arbiter  128  of the LTE frequency region employed by LTE device  108 . Based on that LTE frequency region, the arbiter  128  selects one or more WiFi frequency channels available for use by the WiFi MAC  104 , and informs the WiFi MAC  104  of the one or more available frequency channels using control signals  134 . For example, the arbiter  128  employs the channel map  138  to select the one or more available WiFi frequency channels based on the LTE frequency region employed by the LTE device  108 . An example mapping is shown in Table 1. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 LTE frequency region 
                 available WiFi frequency channels 
               
               
                   
                   
               
             
             
               
                   
                 0 
                 3-11 
               
               
                   
                 1 
                 5-11 
               
               
                   
                   
               
             
          
         
       
     
     Referring to Table 1, the benefit of employing LTE frequency regions characterized by type of unwanted interference can be seen. LTE region 0 is characterized by out-of-band emission, while LTE region 1 is characterized by spurious emission. Spurious emission is generally more wideband than out-of-band emission, and so effects more WiFi channels than out-of-band emission. Therefore more WiFi channels are available when the LTE device  108  is transmitting in LTE region 0 than when the LTE device  108  is transmitting in LTE region 1. 
     Similar mappings can be used for other sorts of transceivers. For example, in some embodiments, user equipment  102  includes a Bluetooth transceiver, and the arbiter  128  employs the channel map  138  to select the available Bluetooth frequency channels based on the LTE frequency sub-region employed by the LTE device  108 . An example mapping is shown in Table 2. 
     
       
         
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 LTE frequency sub-region 
                 available Bluetooth frequency channels 
               
               
                   
                   
               
             
             
               
                   
                 0 
                 11-79 
               
               
                   
                 1 
                 21-79 
               
               
                   
                   
               
             
          
         
       
     
     In some embodiments, the LTE frequency regions are divided into LTE frequency sub-regions having non-uniform bandwidths. Different channels in one transceiver generate different levels of interference for the other transceiver in the user equipment  102 . In terms of frequency, the closer an LTE channel is to a WiFi channel, the more interference an LTE transmission will produce in the WiFi channel. Therefore, in some embodiments, the LTE sub-regions nearer the WiFi band are narrower than the LTE sub-regions farther from the WiFi band. In one embodiment, information signals  132  inform the arbiter  128  of the LTE frequency sub-region employed by the LTE device  108 . Based on those LTE frequency sub-regions, the arbiter  128  selects one or more WiFi frequency channels available for use by the WiFi MAC  104 , and informs the WiFi MAC  104  of the one or more available frequency channels using control signals  134 . For example, the arbiter  128  employs the channel map  138  to select the one or more available WiFi frequency channels based on the LTE frequency sub-region employed by the LTE device  108 . 
     In some embodiments, the arbiter  128  uses the channel map  138  to assign channels to the WiFi MAC  104 , as described above. In other embodiments, the arbiter  128  can assign channels to the WiFi MAC  104  in other ways, for example by using programmable thresholds or frequency offsets to give sufficient frequency gaps between the LTE and WiFi operating regions. It should be noted that the mappings and regions of  FIG. 2  and Tables 1 and 2 are shown by way of example. Other embodiments can feature other mappings and regions. 
       FIG. 3  shows a process  300  for user equipment  102  of  FIG. 1  according to an embodiment where the arbiter  128  assigns WiFi channels to the WiFi MAC  104  based on the LTE channels used by the LTE device  108 . Although in the described embodiments the elements of process  300  are presented in one arrangement, other embodiments may feature other arrangements. For example, in various embodiments, some or all of the elements of process  300  can be executed in a different order, concurrently, and the like. Also some elements of process  300  may not be performed, and may not be executed immediately after each other. In addition, some or all of the elements of process  300  can be performed automatically, that is, without human intervention. 
     Referring to  FIG. 3 , at  302 , the LTE controller  112  selects one of a plurality of LTE frequency regions, where each LTE frequency region is characterized by a respective type of unwanted interference. The LTE frequency region can be assigned to the LIE device  108 , for example, by a base station, also referred to as an LTE evolved Node B (eNB or eNodeB). Subsequently, at  304 , the LTE device  108  transmits, according to the LTE protocol, wireless signals  126  in the selected frequency region. 
     At  306 , the LTE controller  112  informs the arbiter  128  of the selected LTE frequency region. In particular, the LTE controller  112  provides the information signal  132 , where the information signal  132  indicates the selected LTE frequency region. For example, the information signal  132  can include the LTE frequency region bits listed in Table 1 above. At  308 , in response to the information signal  132 , the arbiter  128  selects available WiFi frequency channels based on the information signal  132 , for example as described above. At  310 , the arbiter  128  informs the WiFi MAC  104  of the selected WiFi frequency channels. In particular, the arbiter  128  provides the control signal  134 , where the control signal  134  indicates the selected WiFi frequency channels. At  312 , the WiFi MAC  104  then transceives the WiFi signals  124  on one or more of the selected WiFi frequency channels. 
     The techniques described herein can also be used by the arbiter  128  to select available LTE channels based on the WiFi channel in use by the WiFi MAC  104 .  FIG. 4  shows a process  400  for user equipment  102  of  FIG. 1  according to an embodiment where the arbiter  128  assigns LTE channels to the LTE device  108  based on the WiFi channels use by the WiFi MAC  104 . Although in the described embodiments the elements of process  400  are presented in one arrangement, other embodiments may feature other arrangements. For example, in various embodiments, some or all of the elements of process  400  can be executed in a different order, concurrently, and the like. Also some elements of process  400  may not be performed, and may not be executed immediately after each other. In addition, some or all of the elements of process  400  can be performed automatically, that is, without human intervention. 
     Referring to  FIG. 4 , at  402 , the WiFi controller  106  selects one of a plurality of WiFi frequency regions, where each WiFi frequency region is characterized by a respective type of unwanted interference. Subsequently, at  404 , the WiFi MAC  104  transmits, according to the WiFi protocol, wireless signals  124  in the selected frequency region. 
     At  406 , the WiFi controller  106  informs the arbiter  128  of the selected WiFi frequency region. In particular, the WiFi controller  106  provides the information signal  130 , where the information signal  130  indicates the selected WiFi frequency region. At  408 , in response to the information signal  130 , the arbiter  128  selects available LTE frequency channels based on the information signal  130 , for example in a manner similar to that described above for the selection of available WiFi channels. At  410 , the arbiter  128  informs the LIE device  108  of the selected LTE frequency channels. In particular, the arbiter  128  provides the control signal  136 , where the control signal  136  indicates the selected LTE frequency channels. At  412 , the LTE device  108  then transceives the LTE signals  126  on one or more of the selected LTE frequency channels. 
     Various embodiments feature one or more of the following advantages. From the viewpoint of an LTE base station, the downlink resource is saved from engaging in unsuccessful transactions resulting from potentially high interference with WiFi transmissions from the user equipment  102 . Thus the downlink resource can be used for other user equipment  102  resulting in better resource utilization efficiency for the base station. From the viewpoint of WiFi devices in user equipment  102 , the WiFi receive resource is saved from unsuccessful receive transactions resulting from potentially high interference with LTE uplink packets. Note these advantages are achieved without changing existing 3GPP LTE standards. 
     Various embodiments of the present disclosure can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations thereof. Embodiments of the present disclosure can be implemented in a computer program product tangibly embodied in a computer-readable storage device for execution by a programmable processor. The described processes can be performed by a programmable processor executing a program of instructions to perform functions by operating on input data and generating output. Embodiments of the present disclosure can be implemented in one or more computer programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Each computer program can be implemented in a high-level procedural or object-oriented programming language, or in assembly or machine language if desired; and in any case, the language can be a compiled or interpreted language. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, processors receive instructions and data from a read-only memory and/or a random access memory. Generally, a computer includes one or more mass storage devices for storing data files. Such devices include magnetic disks, such as internal hard disks and removable disks, magneto-optical disks; optical disks, and solid-state disks. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM disks. Any of the foregoing can be supplemented by, or incorporated in, AS ICs (application-specific integrated circuits). 
     A number of implementations have been described. Nevertheless, various modifications may be made without departing from the scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.