Patent Publication Number: US-9414408-B2

Title: Multi-radio controller and methods for preventing interference between co-located transceivers

Description:
This application is a continuation of U.S. patent application Ser. No. 14/153,789, filed Jan. 13, 2014, which is a continuation of U.S. patent application Ser. No. 12/346,453, filed on Dec. 30, 2008, now issued as U.S. Pat. No. 8,630,272, each of which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     Some embodiments pertain to wireless communications. Some embodiments pertain to wireless devices that include more than one transceiver, such as a wireless wide area network (WWAN) transceiver and a wireless local area network (WLAN) transceiver. Some embodiments pertain to preventing interference between co-located radios on a multi-radio platform. 
     BACKGROUND 
     Many wireless devices today include more than one radio transceiver for communicating with more than one wireless network, such as a wireless wide area network and local area network. One issue with these multi-transceiver devices is that the communications of one transceiver may interfere with the communications of another transceiver. 
     Thus, there are general needs for multi-radio devices and methods that help reduce and/or eliminate conflicts between the co-located transceivers of a multi-radio device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a multi-radio communication environment including a multi-radio device (MRD) in accordance with some embodiments; 
         FIG. 2  illustrates communications in a multi-radio communication environment in accordance with some embodiments; and 
         FIG. 3  is a procedure for receiving downlink data frames on a multi-radio device in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Examples merely typify possible variations. Individual components and functions are optional unless explicitly required, and the sequence of operations may vary. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims. 
       FIG. 1  illustrates a multi-radio communication environment including a multi-radio device (MRD) in accordance with some embodiments. Multi-radio communication environment  100  may include MRD  102 , wireless local area network (WLAN) access point (AP)  104 , and wireless wide-area network (WWAN) base station  106 . MRD  102  may include co-located radio transceivers for communicating with both WLAN AP  104  and WWAN base station  106 . In some embodiments, MRD  102  includes WLAN transceiver  114  for communicating with WLAN AP  104  and WWAN transceiver  116  for communicating with WWAN base station  106 . MRD  102  may also include multi-radio controller (MRC)  115  to coordinate the activities of WLAN transceiver  114  and WWAN transceiver  116  to, among other things, mitigate and possibly prevent interference between the co-located transceivers  114  and  116 . MRD  102  may include other functional elements not illustrated. 
     In some embodiments, WWAN transceiver  116  and WWAN base station  106  may communicate downlink and uplink subframes  121  during active periods. In these embodiments, MRC  115  may configure WLAN transceiver  114  and WLAN AP  104  to communicate between the active periods. In these embodiments, MRC  115  may cause WLAN transceiver  114  to transmit triggering frame  101  immediately after an active period of WWAN transceiver  116 . Triggering frame  101  may indicate at least a duration of a transmission opportunity (T TXOP ). In response to receipt of the triggering frame, WLAN AP  104  may transmit downlink data frame  105  within the transmission opportunity. In these embodiments, the duration of the transmission opportunity may be set at triggering frame  101  to allow downlink data frame  105  to be received by WLAN transceiver  114  between the active periods of WWAN transceiver  116 . These embodiments are discussed in more detail below. 
     In some embodiments, WLAN transceiver  114  may operate in a power-saving delivery mode and instruct WLAN access point  104  to refrain from transmitting downlink data frames to WLAN transceiver  114  unless requested by WLAN transceiver  114 . WLAN transceiver  114  may also operate in accordance with a reverse direction (RD) protocol, and MRC  115  may cause WLAN transceiver  114  to set a bit in triggering frame  101  to indicate that WLAN transceiver  114  is granting permission to WLAN access point  104  to send data. These embodiments are discussed in more detail below. 
     MRD  102  may be almost any wireless communication device including both fixed communication stations as well as mobile communication devices. Examples of MRDs  102  may include a desktop, laptop or portable computer with wireless communication capability, a web tablet, a wireless or cellular telephone, an access point or other device that may receive and/or transmit information wirelessly. Although the various functional elements of MRD  102  are illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, application-specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements of MRD  102  may refer to one or more processes operating on one or more processing elements. 
     In some embodiments, WWAN transceiver  116 , WLAN transceiver  114  and MRC  115  may be provided on a dual-mode wireless card for use in a laptop or personal computer. In some embodiments, WWAN transceiver  116 , WLAN transceiver  114  and MRC  115  may be provided or fabricated on a single integrated circuit. 
     The term “WWAN” may refer to devices and networks that communicate using a broadband or wideband wireless access communication technique, such as orthogonal frequency division multiple access (OFDMA), that communicate during downlink and uplink subframes which may potentially interfere with the spectrum utilized by WLAN transceiver  114 , including interference due to out-of-band (OOB) emissions. In some embodiments, WWAN transceiver  116  may be a Worldwide Interoperability for Microwave Access (WiMAX) transceiver, and WWAN base station  106  may be a WiMAX base station configured to communicate in accordance with at least some Electrical and Electronics Engineers (IEEE) 802.16 communication standards for wireless metropolitan area networks (WMANs) including variations and evolutions thereof, although the scope of the embodiments is not limited in this respect. For more information with respect to the IEEE 802.16 standards, please refer to “IEEE Standards for Information Technology—Telecommunications and Information Exchange between Systems” Metropolitan Area Networks—Specific Requirements—Part 16: “Air Interface for Fixed Broadband Wireless Access Systems,” May 2005 and related amendments and versions thereof. In some other embodiments, WWAN transceiver  116  and WWAN base station  106  may communicate in accordance with at the 3rd Generation Partnership Project (3GPP) Universal Terrestrial Radio Access Network (UTRAN) Long Term Evolution (LTE) communication standards, Release 8, March 2008, including variations and evolutions thereof, although the scope of the embodiments is not limited in this respect. 
     WLAN transceiver  114  may be a wireless local area network or a Wireless Fidelity (WiFi) transceiver and may communicate with WLAN AP  104  in accordance with one or more of the IEEE 802.11-2007 and/or IEEE 802.11(n) standards and/or proposed specifications. For more information with respect to the IEEE 802.11 standards, please refer to “IEEE Standards for Information Technology—Telecommunications and Information Exchange between Systems”—Local Area Networks—Specific Requirements—Part 11 “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY), ISO/IEC 8802-11: 1999” and related amendments/versions. 
     The use of the terms WiFi, WLAN, WiMAX and LTE are not intended to restrict the embodiments to any of the requirements of the standards and specifications relevant to these technologies unless specifically claimed. 
     In some multiple-input, multiple-output (MIMO) embodiments, WWAN transceiver  116  may use two or more antennas  118  for communications, and WWAN base station  106  may use two or more antennas  120  for communications. In some MIMO embodiments, WLAN transceiver  114  may use two or more antennas  125 , and WLAN AP  104  may use two or more antennas  123  for communicating. In these MIMO embodiments, the antennas of a single transceiver may be effectively separated from each other to take advantage of spatial diversity and the different channel characteristics that may result between the stations. The antennas may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF or microwave signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some embodiments, the antennas of a transceiver may be separated by up to 1/10 of a wavelength or more. 
     In some WiMAX embodiments, WWAN base station  106  communicates with WWAN transceiver  116  within OFDMA downlink and uplink subframes  121  during and the active periods. In these embodiments, the downlink and uplink subframes are time-division multiplexed using the same set of frequency subcarriers. 
     In some LTE embodiments, WWAN base station  106  transmits to WWAN transceiver  116  using OFDMA downlink subframes, and WWAN transceiver  116  transmits to WWAN base station  106  using a single-carrier multiple access uplink. These communications may take place during active periods. The downlink subframes and the single-carrier multiple access uplink may comprise non-interfering frequency subcarriers. 
       FIG. 2  illustrates communications in a multi-radio communication environment in accordance with some embodiments. WWAN transceiver  116  and WWAN base station  106  ( FIG. 1 ) communicate during active periods  203 . As illustrated in  FIG. 2 , WWAN transceiver  116  may receive during active periods  203  designated by RX 1  and may transmit during active periods  203  designated by TX 1 . Active periods  203  may be periodic (e.g., regularly repeat) having active period duration  213  and an active interval period (P)  215 . Active period duration  213  may be a burst length. As illustrated in  FIG. 2 , active period  203 A has active period start time  211 , active period duration  213 , and end time  207 . 
     In accordance with embodiments, to help mitigate interference with WWAN communications, MRC  115  ( FIG. 1 ) is configured to cause WLAN transceiver  114  to transmit triggering frame  201  to WLAN AP  104  immediately after active period  203 A. Triggering frame  201  may indicate at least duration  206  of a transmission opportunity (T TXOP ). In response to receipt of triggering frame  201 , WLAN AP  104  may transmit downlink data frame  205  within the transmission opportunity. In these embodiments, duration  206  of the transmission opportunity is set at triggering frame  201  to allow downlink data frame  205  to be received between active periods  203 . 
     In these embodiments, MRC  115  ( FIG. 1 ) may determine duration  206  of the transmission opportunity based on a time between consecutive active periods  203  less the length of triggering frame  201 . MRC  115  ( FIG. 1 ) may also determine duration  206  of the transmission opportunity from active period duration  213  and active interval period  215 . In these embodiments, the time between the consecutive active periods  203  may be the difference between end time  207  and start time  209  of two consecutive active periods  203 . 
     In some embodiments, the duration  206  of the transmission opportunity (t TXOP ) may be determined in accordance with the following equation:
 
 t   TXOP =min( t   x   −t   TRIGGER   _   END   ,TXOP   max ).
 
     In this equation, TXOPmax indicates a maximum network transmit opportunity duration allowed by WLAN AP  104 , t x  may be any value in the range [t TRIGGER   _   END , t START ], t START  may refer to triggering frame start time  217 , and t TRIGGER   _   END  may refer to triggering frame end time  219 . 
     In some embodiments, WLAN transceiver  114  may transmit triggering frame  201  when WLAN transceiver  114  is operating in a power-saving delivery mode and when WLAN transceiver  114  wishes to receive downlink data from WLAN AP  104 . During the power-saving delivery mode, WLAN AP  104  may refrain from transmitting downlink data frames to WLAN transceiver  114  until downlink data is requested by WLAN transceiver  114 . In these embodiments, WLAN transceiver  114  may inform WLAN AP  104  that it is entering a power-saving delivery mode by setting a power saving (PS) bit in a null frame, although the scope of the embodiments is not limited in this respect. In some embodiments, the power-saving delivery mode may be an unscheduled-automatic power saving delivery (U-APSD) mechanism in accordance with the IEEE 802.11(n) specifications referenced above, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, WLAN transceiver  114  and WLAN AP  104  may operate in accordance with a reverse direction (RD) protocol. In these embodiments, MRC  115  ( FIG. 1 ) may set a Reverse Direction Grant (RDG) “More PPDU” bit of a high-throughput control (HTC) field in a MAC frame (e.g., to one) to indicate that WLAN transceiver  114  is granting permission to WLAN AP  104  to send data. In these embodiments, the “More PPDU” bit may be set (e.g., to zero) in downlink data frame  205  transmitted by the WLAN AP  104  to indicate that no additional frames will be transmitted by WLAN AP  104 . In some embodiments, the RD protocol may be in accordance with IEEE. 802.11(n) specifications referenced above, although the scope of the embodiments is not limited in this respect. 
     In these embodiments that operate in accordance with an RD protocol, once WLAN transceiver  114  has obtained a transmission opportunity, it may grant permission to WLAN AP  104  to send information back during the transmission opportunity. In some of these embodiments, the RD initiator (e.g., WLAN transceiver  114 ) may send permission to the RD responder (e.g., WLAN AP  104 ) using a RDG in the RDG/More PPDU bit of the HTC field in the MAC frame. In these embodiments, the “More PPDU” bit may be set to one in triggering frame  201  to indicate that it is granting permission to WLAN AP  104  to send data. In these embodiments, the “More PPDU” bit may be set to zero in downlink data frame  205  transmitted by WLAN AP  104  to indicate that no more frames will be transmitted by WLAN AP  104 . Without the implementation of an RD protocol, the initiating station would have to capture and reserve time on a contention-based RF medium for each unidirectional data transfer, making it difficult to avoid conflicts with communications of the WWAN transceiver  116  during active periods  203 . 
     Through a combination of a power-saving delivery mechanism, such as U-APSD, and an RD protocol, down-link traffic for a WLAN transceiver may be controlled to help assure that the WLAN transceiver operates between active periods  203  of a co-located WWAN transceiver, thus preventing potential interference between the WLAN and the WWAN. 
     In some embodiments, prior to transmission of downlink data frame  205 , WLAN AP  104  may transmit a block-acknowledge (BA)  224  to acknowledge receipt of triggering frame  201 . In this situation, the More PPDU bit may be set to indicate that an additional frame (i.e., downlink data frame  205 ) will follow BA  224 . As illustrated in  FIG. 2 , WLAN transceiver  114  may transmit BA  222  to acknowledge receipt of downlink data frame  205 . In these embodiments, by restricting the length of the transmission opportunity, downlink data frame  205 , BA  224  and BA  222 , including triggering frame  201 , may fit within the time between active periods  203 . 
     In some embodiments, triggering frame  201  may comprise either a data frame, such as a MAC layer Quality-of-Service (QOS) data frame, or a null frame, and downlink data frame  205  may comprise a QOS data frame, although the scope of the embodiments is not limited in this respect. In some embodiments, a duration/ID field of the MAC header of triggering frame  201 , in accordance with the IEEE 802.11 specifications, may be used to indicate the duration of the transmit opportunity, although the scope of the embodiments is not limited in this respect. 
     In some embodiments, a method for receiving downlink data frames from a WLAN AP is provided. In these embodiments, MRC  115  ( FIG. 1 ) may be configured to determine duration  213  and period  215  of active period  203  from co-located WWAN transceiver  116  and calculate duration  206  of a transmission opportunity. MRC  115  ( FIG. 1 ) may also be configured to instruct WLAN transceiver  114  to transmit triggering frame  201  immediately after active period  203  and indicate duration  206  of the transmission opportunity within triggering frame  201 . These embodiments are discussed in more detail below. 
       FIG. 3  is a procedure for receiving downlink data frames on a multi-radio device in accordance with some embodiments. Procedure  300  may be performed by a multi-radio controller of a wireless communication device that included co-located transceivers, such as WLAN transceiver  114  and WWAN transceiver  116 . 
     In operation  302 , the multi-radio controller determines whether or not the WLAN transceiver is in a power-saving delivery mode. When the WLAN transceiver is not in power-saving delivery mode, additional operations of procedure  300  are not performed and operation  302  is repeated until the WLAN transceiver enters a power-saving delivery mode. When the WLAN transceiver is in a power-saving delivery mode, operation  304  through  310  may be performed. 
     In operation  304 , the multi-radio controller determines whether or not the WLAN transceiver desires to receive downlink data from the WLAN AP. When the WLAN transceiver desires to receive downlink data from the WLAN access point, operation  306  is performed. If the WLAN transceiver desires to receive downlink data from the WLAN access point, operation  306  may continue to be performed until the WLAN transceiver desires to receive downlink data from the WLAN access point. 
     In operation  306 , the multi-radio controller determines the duration and period of WWAN active periods, such as active periods  203  ( FIG. 2 ). 
     In operation  308 , the multi-radio controller calculates a transmission opportunity duration, such as duration  206  ( FIG. 1 ). 
     In operation  310 , the multi-radio controller instructs the WLAN transceiver, such as WLAN transceiver  114 , to send a triggering frame to indicate the transmission opportunity duration and to grant permission to the WLAN AP to send data. In these embodiments, the triggering frame may have the RDG “More PPDU” bit set to grant permission to send data. 
     Although the individual operations of procedure  300  are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently, and nothing requires that the operations be performed in the order illustrated. 
     Unless specifically stated otherwise, terms such as “processing,” “computing,” “calculating,” “determining,” “displaying,” or the like, may refer to an action and/or process of one or more processing or computing systems or similar devices that may manipulate and transform data represented as physical (e.g., electronic) quantities within a processing system&#39;s registers and memory into other data similarly represented as physical quantities within the processing system&#39;s registers or memories, or other such information storage, transmission or display devices. Furthermore, as used herein, a computing device includes one or more processing elements coupled with computer-readable memory that may be volatile or non-volatile memory or a combination thereof. 
     Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable medium, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable medium may include any tangible medium for storing or transmitting information in a form readable by a machine (e.g., a computer). For example, a computer-readable medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and others. 
     The Abstract is provided to comply with 37 C.F.R. Section 1.72(b) requiring an abstract that will allow the reader to ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to limit or interpret the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.