Abstract:
Apparatus having corresponding methods and computer-readable media comprise: a Mobile Wireless Standards (MWS) transceiver configured to transceive MWS signals in accordance with a schedule, wherein the schedule is based on link status reports transmitted by the MWS transceiver as part of the MWS signals; one or more Industrial, Scientific and Medical (ISM) band transceivers, wherein each ISM band transceiver is configured to transceive ISM band signals; and an arbiter configured to modify the link status reports, prior to transmission of the link status reports, based on at least one of i) an expected transmission of the ISM band signals by one of the ISM band transceivers, and ii) an expected reception of the ISM band signals by one of the ISM band transceivers.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This disclosure claims the benefit of U.S. Provisional Patent Application Ser. No. 61/521,689, filed on Aug. 9, 2011, entitled “FEEDBACK SPOOFING 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 un-licensed 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 Mobile Wireless Standards (MWS) transceiver configured to transceive MWS signals in accordance with a schedule, wherein the schedule is based on link status reports transmitted by the MWS transceiver as part of the MWS signals; one or more Industrial, Scientific and Medical (ISM) band transceivers, wherein each ISM band transceiver is configured to transceive ISM band signals; and an arbiter configured to modify the link status reports, prior to transmission of the link status reports, based on at least one of i) an expected transmission of the ISM band signals by one of the ISM band transceivers, and ii) an expected reception of the ISM band signals by one of the ISM band transceivers. 
     Embodiments of the apparatus can include one or more of the following features. In some embodiments, the arbiter is further configured to modify the link status reports based on at least one of i) a priority of traffic carried by the MWS signals, and ii) a priority of traffic carried by the ISM band signals. In some embodiments, the link status reports include a channel condition value; and wherein the arbiter is further configured to modify the channel condition value in the link status reports based on the expected transmission of the ISM band signals by one of the ISM band transceivers. In some embodiments, the link status reports include a traffic demand value; and wherein the arbiter is further configured to modify the traffic demand value in the link status reports based on the expected reception of the ISM band signals by one of the ISM band transceivers. In some embodiments, the MWS transceiver comprises at least one of: a Long Term Evolution (LTE) transceiver; and a Worldwide Interoperability for Microwave Access (WiMAX) transceiver. In some embodiments, the one or more ISM band transceivers comprise at least one of: a WiFi transceiver; a Bluetooth transceiver; and a ZigBee transceiver. 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: transceiving Mobile Wireless Standards (MWS) signals in accordance with a schedule, wherein the schedule is based on link status reports; transmitting the link status reports as part of the MWS signals; transceiving Industrial, Scientific and Medical (ISM) band signals; and modifying the link status reports, prior to transmitting the link status reports, based on at least one of i) an expected transmission of the ISM band signals from the electronic device, and ii) an expected reception of the ISM band signals by the electronic device. 
     Embodiments of the method can include one or more of the following features. Some embodiments comprise modifying the link status reports based on at least one of i) a priority of traffic carried by the MWS signals, and ii) a priority of traffic carried by the ISM band signals. In some embodiments, the link status reports include a channel condition value; and the method further comprises modifying the channel condition value in the link status reports based on the expected transmission of the ISM band signals from the electronic device. In some embodiments, the link status reports include a traffic demand value; and the method further comprises modifying the traffic demand value in the link status reports based on the expected reception of the ISM band signals by the electronic device. In some embodiments, the MWS signals comprise at least one of: Long Term Evolution (LTE) signals; and Worldwide Interoperability for Microwave Access (WiMAX) signals. In some embodiments, the one or more ISM band signals comprise at least one of: WiFi signals; Bluetooth signals; and ZigBee signals. 
     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: transceiving Mobile Wireless Standards (MWS) signals in accordance with a schedule, wherein the schedule is based on link status reports; transmitting the link status reports as part of the MWS signals; transceiving Industrial, Scientific and Medical (ISM) band signals; and modifying the link status reports, prior to transmitting the link status reports, based on at least one of i) an expected transmission of the ISM band signals from the electronic device, and ii) an expected reception of the ISM band signals by the electronic device. 
     Embodiments of the computer-readable media can include one or more of the following features. In some embodiments, the functions further comprise: modifying the link status reports based on at least one of i) a priority of traffic carried by the MWS signals, and ii) a priority of traffic carried by the ISM band signals. In some embodiments, the link status reports include a channel condition value; and the functions further comprise modifying the channel condition value in the link status reports based on the expected transmission of the ISM band signals from the electronic device. In some embodiments, the link status reports include a traffic demand value, and the functions further comprise modifying the traffic demand value in the link status reports based on the expected reception of the ISM band signals by the electronic device. In some embodiments, the MWS signals comprise at least one of: Long Term Evolution (LTE) signals; and Worldwide Interoperability for Microwave Access (WiMAX) signals. In some embodiments, the one or more ISM band signals comprise at least one of: WiFi signals; Bluetooth signals; and ZigBee signals. 
     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  shows a process for the communication system of  FIG. 1  according to an embodiment where the arbiter modifies a Channel Quality Indicator (CQI) value in a link status report. 
         FIG. 3  shows a process for the communication system of  FIG. 1  according to an embodiment where the arbiter modifies a Buffer Status Report (BSR) value in a link status report. 
     
    
    
     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 through feedback spoofing. Several wireless communications technologies schedule transmissions to and from electronic devices, also referred to herein as “user equipment,” based on feedback from the user equipment. According to the described embodiments, a user equipment modifies (that is, “spoofs”) this feedback to affect the schedule in order to prevent interference between different wireless technologies. 
     This feedback generally takes the form of link status reports that include channel condition values, traffic demand values, and the like. One example of a channel condition value is the Channel Quality Indicator (CQI) employed by LTE (Long Term Evolution) and WiMAX systems. One example of a traffic demand value is the Buffer Status Report (BSR) employed by LTE systems. In the following description, various embodiments are described as using CQIs and/or BSRs. However, the present disclosure applies to any sort of link status report. Furthermore, while coexistence is described for Mobile Wireless Standards (MWS) transceivers and Industrial, Scientific and Medical (ISM) transceivers, the present disclosure applies to other sorts of wireless communication technologies as well. 
       FIG. 1  shows elements of a communication system  100  according to one embodiment. Although in the described embodiments the elements of communication system  100  are presented in one arrangement, other embodiments may feature other arrangements. For example, elements of communication system  100  can be implemented in hardware, software, or combinations thereof. 
     Referring to  FIG. 1 , 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 one Mobile Wireless Standards (MWS) transceiver and two Industrial, Scientific and Medical (ISM) band transceivers. 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 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 ISM band transceivers include a WiFi media access controller (MAC)  104  and a Bluetooth controller  106 , and the MWS transceiver is implemented as 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 , the Bluetooth controller  106  uses one or more antennas  112 , and the LTE device  108  uses one or more antennas  114 . In some embodiments, one or more of the antennas  110 ,  112 ,  114  can be combined. 
     Each transceiver communicates with one or more respective devices. Each ISM band transceiver transceives ISM band signals. Each MWS transceiver transceives MWS signals in accordance with a schedule. The schedule is based on link status reports transmitted by the MWS transceiver as part of the MWS signals. In the example of  FIG. 1 , the WiFi MAC  104  exchanges WiFi signals  116  with one or more WiFi devices  118  over a WiFi local-area network (WLAN)  120 . The WLAN  120  can operate in ad-hoc mode or infrastructure mode. In ad-hoc mode, the WiFi devices  118  can include smartphones, other computers, and the like. In infrastructure mode, the WiFi devices  118  can include access points, and the like. The Bluetooth controller  106  exchanges Bluetooth signals  122  with a Bluetooth device  124  over a Bluetooth link  126 . The Bluetooth device  124  can be a Bluetooth headset or the like. The LTE device  108  exchanges LTE signals  140  with a base station  128 , also referred to as an LTE evolved Node B (eNB or eNodeB), over an LTE link  130 . The LTE device  108  transceives the LIE signals  140  in accordance with the schedule  132 . The schedule  132  is based on link status reports  134  transmitted by the LTE device  108  as part of the LTE signals  140 . 
     The user equipment  102  also includes an arbiter  136  that schedules the WiFi MAC  104 , the Bluetooth controller  106 , and the LTE device  108 . The arbiter  136  can be implemented as a processor. Processors according to various embodiments can be fabricated as one or more integrated circuits. The arbiter  136  receives the schedule  132  from the base station  128 , and can store the schedule  132  in a memory  138 . The arbiter  136  causes the LTE device  108  to transceive the LTE signals  140  in accordance with the schedule  132 . The arbiter  136  also generates link status reports  134 , and can store the link status reports  134  in the memory  138 . The arbiter  136  causes the LTE device  108  to transmit the link status reports  134  to the base station  128  as part of the LTE signals  140 . The base station  128  generates the schedules  132  based on the link status reports  134 . 
     The link status reports  134  can include channel condition values such as Channel Quality Indicators (CQI), traffic demand values such as Buffer Status Report (BSR), and the like. In conventional systems, these values represent actual conditions. But in the described embodiments, in order to achieve coexistence between the wireless technologies implemented in the user equipment  102 , the arbiter  136  modifies one or more of these values in order to affect the schedules  132 . For example, the arbiter  136  can modify a channel condition value in a link status report  134  in response to an expected transmission of ISM band signals by one of the ISM band transceivers. This modification can be implemented so as to postpone a transmission of MWS signals to the user equipment  102  so the transmission of the ISM band signals does not interfere with reception of the MWS signals. 
     As another example, the arbiter  136  can modify a traffic demand value in a link status report  134  in response to an expected reception of ISM band signals by one of the ISM band transceivers. This modification can be implemented so as to postpone a transmission of MWS signals by the user equipment  102  so the transmission of the MWS signals does not interfere with reception of the ISM signals. The arbiter  136  can also modify the link status reports  134  based on other factors, such as priorities of the traffic carried by the MWS and ISM band signals, and the like. Specific implementations of these modifications are discussed in detail below. 
       FIG. 2  shows a process  200  for the communication system  100  of  FIG. 1  according to an embodiment where the arbiter  136  modifies a Channel Quality Indicator (CQI) value in a link status report  134 . Although in the described embodiments the elements of process  200  are presented in one arrangement, other embodiments may feature other arrangements. For example, in various embodiments, some or all of the elements of process  200  can be executed in a different order, concurrently, and the like. Also some elements of process  200  may not be performed, and may not be executed immediately after each other. 
     Referring to  FIG. 2 , at  202 , the base station  128  sends a CQI request message to the user equipment  102 . As used herein, the term “message” generally refers to a wireless electronic signal representing a digital message. At  204 , arbiter  136  generates a CQI report that includes one or more CQI values. The CQI values can include resource block values indicating wideband or subband indices, modulation and coding scheme (MCS) index values, transmission mode selection values, and the like. As part of generating the CQI report, arbiter  136  can modify one or more of the CQI values in response to an expected transmission of WiFi signals  116  by the WiFi MAC  104 , or an expected transmission of Bluetooth signals  122  by Bluetooth controller  106 . For example, the arbiter  136  can change the MCS index value to a low or zero value. 
     The arbiter  136  can base the modification on traffic priorities as well. The frequency resolution of the CQI measurement can be either wideband (that is, for the entire signal bandwidth) or narrowband (that is, for a single subband or a group of the subbands). In the case of a wideband CQI measurement, if the priority of the expected ISM transmit traffic exceeds a predetermined ISM transmit threshold priority, the user equipment  102  modifies the wideband CQI to have an MCS index that is lower than the calculated MCS index. The priority of the ISM traffic is calculated according to factors such as traffic type, quality of service (QoS), and the like. The ISM transmit threshold priority is programmable. The amount to decrease MCS index can depend on an estimate of the LTE receive traffic amount, priority, radio frequency (RF) filters, antenna isolation and band separation between ISM transmit and LTE receive, LTE receiver performance and capability, and the like. In addition, the LTE sounding signal power may be lowered, or the sounding signal may not be sent, according to the lower or zero MCS feedback. 
     In the case of a narrowband CQI measurement, if the priority of the expected ISM transit traffic exceeds a predetermined threshold ISM transmit priority, the user equipment  102  modifies the narrowband CQI to have an MCS index that is lower than the calculated MCS index for subbands that are close to the ISM band. Compared to the wideband case, this narrowband case can move the LTE receive band to subbands far from the ISM transmit band. The priority of the ISM traffic is calculated according to factors such as traffic type, QoS, and the like. The threshold ISM transmit priority is programmable. The amount to decrease the MCS index can depend on an estimate of LTE receive traffic amount, priority, RF filters, antenna isolation and band separation between ISM transmit and LTE receive, LTE receiver performance and capability, and the like. 
     In one embodiment, the arbiter  136  has knowledge of the collision pattern between the LTE receive and ISM transmit signals. Before a collision occurs, the arbiter  136  estimates the actual MCS based on the channel condition and the interference from the ISM transmit signals. The arbiter  136  can calibrate the MCS based on different configurations, for example depending on factors such as LTE transmission configuration, antenna isolation, filter specifications, and the like. 
     At  206 , the arbiter  136  causes the LTE device  108  to send a CQI report message to the base station  128 . The CQI report includes the modified CQI value(s). At  208 , the base station  128  generates the schedule  132  based on the modified CQI value(s). However, note that LTE base stations  128  are not obligated to follow CQI feedback from the user equipment  102 . At  210 , the base station  128  sends downlink traffic to the user equipment  102 , according to the schedule  132 , at a time when the downlink traffic will not suffer from interference from the expected ISM transmit traffic. 
       FIG. 3  shows a process  300  for the communication system  100  of  FIG. 1  according to an embodiment where the arbiter  136  modifies a Buffer Status Report (BSR) value in a link status report  134 . 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. 
     Referring to  FIG. 3 , at  302 , the base station  128  sends a BSR request message to the user equipment  102 . However, user equipment  102  is not required to wait for a BSR request message, and can send a BSR message report without first receiving a BSR request message under certain conditions. At  304 , arbiter  136  generates a BSR that includes one or more BSR values. 
     The BSR values can include a BSR traffic amount value that represents an amount of LTE uplink traffic buffered at user equipment  102  for transmission to the base station  128 . The BSR traffic amount value is calculated in terms of aggregate traffic of logical channels in each logical channel group (LCG). Each LCG can be selected based on the priority and quality of service (QoS) of logical channels. A BSR can be triggered when 1) data are generated for uplink with a higher priority than any existing data (if any), or 2) a periodic BSR timer expires (for example every 5 subframes). As part of generating the BSR, arbiter  136  can modify one or more of the BSR values in response to an expected reception of WiFi signals  116  by the WiFi MAC  104 , or an expected reception of Bluetooth signals  122  by Bluetooth controller  106 . For example, the arbiter  136  can change the BSR traffic amount value to a lower or zero value. 
     The arbiter  136  can base the modification on traffic priorities as well. If the priority of the expected ISM receive traffic exceeds a predetermined ISM receive threshold priority, the user equipment  102  modifies the BSR traffic amount value to have a value that is lower than the calculated BSR traffic amount value. The priority of the ISM traffic is calculated according to factors such as traffic type, QoS, and the like. The ISM receive threshold priority is programmable. The amount to decrease the BSR traffic amount value can depend on the priority and QoS of the LTE transmit traffic, an estimate of the ISM traffic amount, priority, radio frequency (RF) filters, antenna isolation and band separation between ISM transmit and LTE receive, ISM receiver performance and capability, and the like. In some embodiments, the BSR traffic amount value is reduced less for high priority MWS traffic and/or high QoS MWS traffic than for low priority MWS traffic and/or low QoS MWS traffic. If the BSR traffic amount value is to be reduced to zero, it is not necessary to send a BSR message. 
     At  306 , the arbiter  136  causes the LTE device  108  to send a BSR message to the base station  128 . The BSR includes the modified BSR value(s). At  308 , the base station  128  generates the schedule  132  based on the modified BSR value(s). At  310 , the base station  128  sends the schedule  132 , or a representation thereof, to the user equipment  102 . At  312 , the arbiter  136  causes the LTE device  108  to send uplink traffic to the base station  128 , according to the schedule  132 , at a time when ISM downlink traffic will not suffer from interference from the LTE uplink traffic. 
     Various embodiments feature one or more of the following advantages. From the viewpoint of an LTE base station  128 , CQI spoofing saves the downlink resource from engaging in unsuccessful transactions resulting from potentially high interference with ISM 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  128 . From the viewpoint of ISM devices in user equipment  102 , BSR spooling saves the ISM receive resource from unsuccessful receive transactions resulting from potentially high interference with LTE uplink packets. Note these advantages are achieved without changing existing 3GPP LTE standards. 
     In some embodiments, the user equipment  102  considers timers for an out-of-sync procedure that monitors the radio links between the user equipment  102  and the base station  128 , such that the user equipment  102  will not lose the connection with the base station  128  due to spooling. For example, the user equipment  102  may not continue CQI spooling until timer T310 expires. According to the 3GPP LTE standard, timer T310 will be started upon N310 consecutive out-of-sync indications, which tells the user equipment  102  that the radio link quality is not good enough. Then, at the expiry of T310, the user equipment  102  either goes to radio resource control idle (RRC_idle) or tries to re-establish RRC connection, with the LIE device  108  turned off within 40 ms. 
     In some embodiments, when expecting ISM traffic, the user equipment  102  considers latency between feedback transmission and its reflection to eNB scheduling (for example, 8 ms for CQI feedback and downlink scheduling assignment for current 3GPP LTE FDD (frequency division duplexing) systems). 
     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, ASICs (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. For example, the user equipment  102  can implement one or both of the embodiments of  FIGS. 2 and 3 . Accordingly, other implementations are within the scope of the following claims.