Abstract:
A device including a first transceiver configured to transmit and receive, using a first antenna, according to a first communication protocol, a second transceiver configured to transmit and receive, using a second antenna, according to the first communication protocol, and a third transceiver configured to transmit and receive, using the second antenna, according to a second communication protocol. A controller is configured to select between a first mode where the first, second, and third transceivers are configured to respectively communicate using the first and second antennas at a same time, and a second mode where the first, second, and third transceivers are configured to respectively communicate using the first and second antennas at different times. In the first mode and the second mode, the controller is further configured to selectively allow the second transceiver to transmit and receive using the second antenna at a same time as the third transceiver.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation of U.S. patent application Ser. No. 13/228,071 (now U.S. Pat. No. 8,780,872), filed on Sep. 8, 2011, which claims the benefit of U.S. Provisional Application No. 61/381,010, filed on Sep. 8, 2010. The entire disclosures of the applications referenced above are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates generally to wireless communications. More particularly, the present disclosure relates to coexistence between wireless local-area networking (WLAN) signals and non-WLAN signals. 
     BACKGROUND 
     The popularity of various wireless networking technologies for handheld platforms has created a need to integrate multiple networking technologies on a single integrated circuit. Of these networking technologies, the two most widely used are wireless local-area networking (WLAN) and Bluetooth. Both of these technologies use the same un-licensed 2.4 GHz Industrial, Scientific and Medical (ISM) band. This situation poses a difficult problem for designing integrated circuits and external logic components that allow both of these technologies to simultaneously coexist. 
     One solution is temporal coexistence (also referred to as time-multiplex coexistence). A conventional temporal coexistence implementation  100  is shown in  FIG. 1 . Referring to  FIG. 1 , a WLAN transceiver  102  and a Bluetooth transceiver  104  share an antenna  106  using a switch  108  that is controlled by a switch controller  110 . Because Bluetooth operates according to a known schedule, switch controller  110  can schedule WLAN transmissions around the Bluetooth transmissions. However, because the Bluetooth schedule is not known to WLAN link partners such as access points and the like, there are frequent collisions on the receive side. These collisions can reduce WLAN performance to one-half of baseline. In addition, it is necessary to include additional protection in switch controller  110  to prevent rate spirals. This additional protection involves additional complexity and cost. 
     SUMMARY 
     In general, in one aspect, an embodiment features an apparatus comprising: a first antenna; a second antenna; a first wireless local-area network (WLAN) transceiver configured to operate, on a dedicated basis, with the first antenna; a second WLAN transceiver configured to share operation of the second antenna; and a non-WLAN transceiver configured to operate with the second antenna with the second WLAN transceiver. 
     In general, in one aspect, an embodiment features a method of transmitting and receiving communications in a device, wherein the device includes a first antenna, a second antenna, a first wireless local-area network (WLAN) transceiver, a second WLAN transceiver, and a non-WLAN transceiver, and wherein the method comprises: operating the first WLAN transceiver with the first antenna on a dedicated basis, operating the second WLAN transceiver and the non-WLAN transceiver with the second antenna on a shared basis. 
     In general, in one aspect, an embodiment features computer-readable media embodying instructions executable by a computer to perform functions comprising: operating a first wireless local-area network (WLAN) transceiver with a first antenna on a dedicated basis; operating a second WLAN transceiver with a second antenna; and operating a non-WLAN transceiver with the second antenna. 
     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. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  shows a conventional temporal coexistence implementation for WLAN and Bluetooth. 
         FIG. 2  shows elements of a dual-technology wireless communication device having multiple antennas according to one embodiment. 
         FIG. 3  shows detail of a shared path module that allows the SoC of  FIG. 2  to receive WLAN signals and Bluetooth signals simultaneously according to one embodiment. 
         FIG. 4  shows a coexistence state diagram for the dual-technology wireless communication device of  FIGS. 2 and 3  according to one embodiment. 
         FIG. 5  shows a spatial coexistence state diagram for the spatial coexistence mode controller of  FIG. 2  according to one embodiment. 
         FIG. 6  shows a temporal coexistence state diagram for the temporal coexistence mode controller of  FIG. 2  according to one embodiment. 
         FIG. 7  shows detail of the SoC of  FIG. 2 , including arbiters to manage the sharing of the shared antenna, according to one embodiment. 
     
    
    
     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. 
     DESCRIPTION 
     Embodiments of the present disclosure provide dual-technology wireless coexistence for multi-antenna devices. In particular, in one aspect, the disclosed embodiments describe coexistence for wireless local-area networking (WLAN) and Bluetooth technologies. However, while the disclosed embodiments are described in terms of WLAN and Bluetooth technologies, the disclosed techniques are applicable to other wireless technologies as well. The wireless technologies can include non-WLAN signals other than Bluetooth. For example, the non-WLAN signals can include near field communication (NFC) signals, FM signals, GPS signals, other ISM band signals, and the like. 
     In the described embodiments, dual-technology wireless coexistence is provided by spatial coexistence. That is, the WLAN signals and Bluetooth signals use different antennas. In some embodiments, all of the antennas can be used for the WLAN signals when Bluetooth signals are absent, not used, or the like. In such embodiments, the WLAN transceiver can be operated in multiple-input and multiple-output (MIMO) mode. In some embodiments, temporal coexistence can be used instead of spatial coexistence under some circumstances, for example when Bluetooth traffic levels are low, when the received Bluetooth or WLAN signal is weak, when the antennas and/or adaptive frequency hopping (AFH) cannot provide sufficient isolation, and the like. In some embodiments, the device can negotiate the number of MIMO streams with an access point, for example using the IEEE 802.11n spatial multiplexing (SM) powersave mechanism or similar mechanisms. 
       FIG. 2  shows elements of a dual-technology wireless communication device  200  having multiple antennas according to one embodiment. Although in the described embodiments, the elements of device  200  are presented in one arrangement, other embodiments may feature other arrangements, as will be apparent to one skilled in the relevant arts based on the disclosure and teachings provided herein. For example, elements of device  200  can be implemented in hardware, software, or combinations thereof. In some embodiments, device  200  is compliant with all or part of IEEE standard 802.11, including draft and approved amendments 802.11a, 802.11b, 802.11d, 802.11e, 802.11g, 802.11h, 802.11i, 802.11k, 802.11n, 802.11p, 802.11r, 802.11s, 802.11u, 802.11v, 802.11w, 802.11z, and 802.11aa, and with the Bluetooth standard issued by the Bluetooth Special Interest Group. 
     Referring to  FIG. 2 , dual-technology wireless communication device  200  includes a dual-technology wireless communication system-on-chip (SoC)  212  electrically coupled to a host module  214  and a front end  228 . Front end  228  is electrically coupled to radio-frequency (RF) antennas  206 A and  206 B. Dual-technology wireless communication device  200  can be implemented as any sort of device, for example including smartphones, personal digital assistants (PDAs), computers, and the like. Antennas  206  can be implemented in any manner. Host module  214  can be implemented in any manner, and can interface with SoC  212  using any sort of interface, for example including Secure Digital Input/Output (SDIO), Universal Serial Bus (USB), universal asynchronous receiver/transmitter (UART), and the like. 
     Dual-technology wireless communication SoC  212  includes a Bluetooth transceiver  204  and two WLAN transceivers  202 A and  202 B. However, the elements of SoC  212  can be implemented separately if desired. For example, Bluetooth transceiver  204  can be implemented on one SoC while WLAN transceivers  202 A and  202 B are implemented on another SoC. In addition, Bluetooth transceiver  204  generally has differential outputs that are terminated with a balun. However, for clarity the balun is not shown in  FIG. 2 . 
     Antenna  206 A is dedicated to WLAN transceiver  202 A (that is, WLAN transceiver  202 A is configured to operate with antenna  206 A on a dedicated basis), while antenna  206 B is shared by WLAN transceiver  202 B and Bluetooth transceiver  204  (that is, WLAN transceiver  202 B and Bluetooth transceiver  204  are configured to operate with antenna  206 B on a shared basis). In other embodiments wireless communication device  200  can include more WLAN transceivers  202  and antennas  206 . In particular, communication device  200  can include N WLAN transceivers  202  and N antennas  206 , where N is an integer greater than one, and where the N antennas  206  include one shared antenna  206  and N−1 dedicated antennas  206 . The techniques disclosed herein apply to such embodiments as well. 
     Front end  228  provides signal paths between transceivers  202 ,  204  and antennas  206 . In particular, front end  228  provides signal paths between WLAN transceiver  202 A and dedicated antenna  206 A. Front end  228  also provides signal paths between shared antenna  206 B, WLAN transceiver  202 B and Bluetooth transceiver  204 . WLAN transceivers  202  are capable of operation in both the 2.4 GHz band and the 5 GHz band. Front end  228  includes diplexers  216 A and  216 B that provide signal paths for both bands between antenna  206   s  and WLAN transceivers  202 . Diplexers  216  can include filters such as band-pass filters and the like as well. Front end  228  also includes power amplifiers (PA) and low-noise amplifiers (LNA) for the WLAN signal paths. In particular, each WLAN receive path includes a low-noise amplifier, and each WLAN transmit path includes a power amplifier. 
     Front end  228  also includes switches  218 ,  208  to switch between transmit and receive signals, and to provide a signal path for Bluetooth signals. In particular, single-pole double-throw (SPDT) switch  218 A switches between 5 GHz WLAN transmit (5GTX) and receive (5GRX) signals, and SPDT switch  218 B switches between 2.4 GHz WLAN transmit (2GTX) and receive (2GRX) signals, for WLAN transceiver  202 A. Similarly, SPDT switch  218 C switches between 5GTX and 5GRX signals for WLAN transceiver  202 A. Single-pole triple-throw (SP3T) switch  208  allows sharing of antenna  206 B between WLAN transceiver  202 B and Bluetooth transceiver  204 . In particular, SP3T switch  208  switches between 2GTX signals, 2GRX signals, and Bluetooth (BT) transmit and receive signals. All of the switches  218 ,  208  operate according to switch control signals  224 . 
     SoC  212  also includes a coexistence mode controller  210 . Coexistence mode controller  210  includes a spatial coexistence mode controller  220  and a temporal coexistence mode controller  222 . Coexistence mode controller  210  provides switch control signals  224  and mode control signals  226 . Transceivers  202 ,  204  operate according to mode control signals  226  as described below. In  FIG. 2 , control signal paths are shown as broken arrows, while communication signal paths are shown as solid arrows. 
     In some embodiments, SoC  212  includes a shared path module that allows SoC  212  to simultaneously receive WLAN signals and Bluetooth signals.  FIG. 3  shows detail of the shared path module according to one embodiment. Referring to  FIG. 3 , SoC  212  includes WLAN transceiver  202 B, Bluetooth transceiver  204 , coexistence mode controller  210 , SP3T switch  208 , an LNA, and shared path module  300 . Shared path module  300  includes five switches S 1 , S 2 , S 3 , S 4  and S 5  and an LNA. Switches S operate according to switch control signal  224 . The operation of switches S is described below. 
       FIG. 4  shows a coexistence state diagram  400  for dual-technology wireless communication device  200  of  FIGS. 2 and 3  according to one embodiment. State diagram  400  includes a state  402  for the spatial coexistence mode, and a state  404  for the temporal coexistence mode. Note some embodiments do not implement the temporal coexistence mode. 
     Coexistence mode controller  210  selects either a spatial coexistence mode (state  402 ) or a temporal coexistence mode (state  404 ). The spatial coexistence mode is a mode in which the WLAN signals and Bluetooth signals simultaneously employ different antennas, and the temporal coexistence mode is a mode in which the WLAN signals and Bluetooth signals employ the same antennas, but at different times. Spatial coexistence mode controller  220  controls transceivers  202 ,  204  when the spatial coexistence mode is selected. Temporal coexistence mode controller  222  controls transceivers  202 ,  204  when the temporal coexistence mode is selected. Coexistence mode controller  210  selects either the spatial coexistence mode or the temporal coexistence mode based on factors including Bluetooth (that is, non-WLAN) traffic levels, Bluetooth (that is, non-WLAN) signal levels, Bluetooth (that is, non-WLAN) operating bandwidth, Bluetooth (that is, non-WLAN) operating frequencies, WLAN signal levels, WLAN traffic levels, WLAN operating bandwidth, WLAN operating frequencies, and the like. For example, when the WLAN operating frequency is 5 GHz, then coexistence is disabled. 
     For example, coexistence mode controller  210  can select the spatial coexistence mode when the Bluetooth traffic level is high, and can select the temporal coexistence mode when the Bluetooth traffic level is low. Coexistence mode controller  210  can determine the Bluetooth traffic level based on the Bluetooth profile, by tracking Bluetooth activity, and the like. For example, Bluetooth activity can be tracked by measuring the number of Bluetooth packets transmitted and/or received during a chosen interval. 
       FIGS. 5 and 6  show coexistence state diagrams for the spatial coexistence mode and the temporal coexistence mode, respectively. In these state diagrams, WLAN transceivers  202 A and  202 B are denoted A and B, respectively. In addition, transmit and receive operations are denoted Tx and Rx, respectively. For example, referring to state  502  in  FIG. 5 , the phrase “WLAN Tx A and B MIMO” indicates that WLAN transceivers  202 A and  202 B can transmit together in MIMO mode. The state diagrams of  FIGS. 5 and 6  are now described in detail. 
       FIG. 5  shows a spatial coexistence state diagram  500  for spatial coexistence mode controller  220  of  FIG. 2  according to one embodiment. State diagram  500  includes three states  502 ,  504 , and  506 . Spatial coexistence mode controller  220  controls transceivers  202 ,  204  with mode control signals  226  according to the selected state. 
     Spatial coexistence mode controller  220  selects state  502  when no Bluetooth traffic is present (No BT). In state  502 , spatial coexistence mode controller  220  allows WLAN transceivers  202  to transmit in multiple-input and multiple-output (MIMO) mode, and to receive in single-input and single-output (SISO) mode. In state  502 , WLAN transceivers  202  can transmit in MIMO mode because the Bluetooth transmit schedule is known to spatial coexistence mode controller  220 . However, WLAN transceivers  202  cannot receive in MIMO mode because the Bluetooth receive schedule is not known to spatial coexistence mode controller  220 . In state  502 , spatial coexistence mode controller  220  employs shared path module  300  to allow WLAN transceiver  202 B to receive. Referring to  FIG. 3 , in state  502 , spatial coexistence mode controller  220  employs switch control signals  224  to open switches S 2 , S 3 , S 4 , and S 5 , and to close switch S 1 . 
     Referring again to  FIG. 5 , spatial coexistence mode controller  220  selects state  504  when Bluetooth receive traffic (BT Rx) is present. In state  504 , spatial coexistence mode controller  220  allows WLAN transceiver  202 A to transmit and receive in SISO mode, and allows WLAN transceiver  202 B to receive in SISO mode but not to transmit. In state  504 , spatial coexistence mode controller  220  employs shared path module  300  to allow simultaneous receive for WLAN transceiver  202 B and Bluetooth transceiver  204 . Referring to  FIG. 3 , in state  504 , spatial coexistence mode controller  220  employs switch control signals  224  to open switches S 1 , S 4 , and S 5 , and to close switches S 2  and S 3 , in shared path module  300 . 
     Referring again to  FIG. 5 , spatial coexistence mode controller  220  selects state  506  when Bluetooth transceiver  204  is transmitting (BT Tx). In state  506 , spatial coexistence mode controller  220  allows WLAN transceiver  202 A to transmit and receive in SISO mode, and allows WLAN transceiver  202 B to neither transmit nor receive. In state  506 , spatial coexistence mode controller  220  employs shared path module  300  to allow Bluetooth transceiver  202  to transmit. Referring to  FIG. 3 , in state  506 , spatial coexistence mode controller  220  employs switch control signals  224  to open switches S 1 , S 2 , S 3 , and S 4 , and to close switch S 5 . 
       FIG. 6  shows a temporal coexistence state diagram  600  for temporal coexistence mode controller  222  of  FIG. 2  according to one embodiment. State diagram  600  includes three states  602 ,  604 , and  606 . Temporal coexistence mode controller  222  controls transceivers  202 ,  204  with mode control signals  226  according to the selected state. 
     Temporal coexistence mode controller  222  selects state  602  when no Bluetooth traffic is present (No BT). In state  602 , temporal coexistence mode controller  222  allows both WLAN transceivers  202 A,  202 B to transmit and receive in MIMO mode. In state  602 , temporal coexistence mode controller  222  employs shared path module  300  to allow WLAN transceiver  202 B to receive. Referring to  FIG. 3 , in state  602 , temporal coexistence mode controller  222  employs switch control signals  224  to open switches S 2 , S 3 , S 4 , and S 5 , and to close switch S 1 . 
     Referring again to  FIG. 6 , temporal coexistence mode controller  222  selects state  604  when Bluetooth receive traffic (BT Rx) is present. In state  604 , temporal coexistence mode controller  222  allows WLAN transceivers  202 A and  202 B to receive in MIMO mode, but not to transmit. In state  604 , temporal coexistence mode controller  222  employs shared path module  300  to allow simultaneous receive for WLAN transceiver  202 B and Bluetooth transceiver  204 . Referring to  FIG. 3 , in state  604 , temporal coexistence mode controller  222  employs switch control signals  224  to open switches S 1 , S 4 , and S 5 , and to close switches S 2  and S 3 , in shared path module  300 . 
     Referring again to  FIG. 6 , temporal coexistence mode controller  222  selects state  606  when Bluetooth transceiver  204  is transmitting (BT Tx). In state  606 , temporal coexistence mode controller  222  allows neither WLAN transceiver  202 A nor WLAN transceiver  202 B to transmit or receive. In state  606 , temporal coexistence mode controller  222  employs shared path module  300  to allow Bluetooth transmit. Referring to  FIG. 3 , in state  606 , temporal coexistence mode controller  222  employs switch control signals  224  to open switches S 1 , S 2 , S 3 , and S 4 , and to close switch S 5 . 
     To transition between MIMO and SISO modes, coexistence mode controller  210  negotiates the number of WLAN spatial streams with the link partner, access point, or the like. For example, coexistence mode controller  210  can indicate a reduced number of spatial streams supported by causing WLAN transmission of a MIMO power save (PS) action frame. On receipt of the frame, an access point shall not transmit rates having more than one stream. This access point function is mandatory for all IEEE 802.11n access points. However, device  200  remains free to transmit any rate 1 or rate 2 stream. The negotiation can be performed dynamically (that is, within an association) or during the association phase. The WLAN link to the peer is not broken, even when the coexistence mode is changed. 
     Some embodiments include one or more arbiters to manage sharing of shared antenna  206 B.  FIG. 7  shows detail of SoC  212  of  FIG. 2  according to one such embodiment. Referring to  FIG. 7 , WLAN Transceiver  202 B includes a WLAN media access controller (MAC)  702 . Bluetooth transceiver  204  includes three non-WLAN MACs: a Bluetooth basic rate/enhanced data rate (BR/EDR) MAC  708 , a Bluetooth low energy (BLE) MAC  710 , and a MAC  712  for other non-WLAN wireless technologies. Coexistence mode controller  210  includes a main arbiter  704  and a non-WLAN arbiter  706 . Non-WLAN arbiter  706  includes a priority table  714 . 
     Non-WLAN MACs  708 ,  710 , and  712  send communication requests to non-WLAN arbiter  706 . Non-WLAN arbiter  706  selects one of the non-WLAN MACs  708 ,  710 , and  712  based on the contents of priority table  714 . Priority table  714  includes programmable priorities based on packet types and the like. Other arbitration schemes can be used as well or instead. 
     WLAN MAC  702  sends communication requests to main arbiter  704 . In temporal coexistence mode, main arbiter  704  grants shared antenna  206 B to either the winner of the non-WLAN arbitration or WLAN MAC  702 . In spatial coexistence mode, main arbiter  704  grants shared antenna  206 B to the winner of the non-WLAN arbitration. 
     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, one or more states in the state diagrams described above may be performed in a different order and still achieve desirable results. Accordingly, other implementations are within the scope of the following claims.