Patent Application
20160100400
The present disclosure relates to wireless communication systems, and more particularly to beacon based time division multiplexing synchronization for multiple radio access technology (RAT) coexistence.
Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). A wireless network, for example a Wireless Local Area Network (WLAN), such as a Wi-Fi network (IEEE 802.11) may include multiple wireless communication devices that communicate with one another.
Many wireless communication devices today are capable of wireless communications using multiple radio access technologies (RATs). These multiple RATs, however, may use wireless spectrum frequency bands that overlap. For example, both IEEE 802.11 and Bluetooth use the 2.4 GHz industrial, scientific, and medical (ISM) band for transmissions. In order to prevent the transmissions associated with one RAT from interfering with transmissions of the other RAT(s), a time division multiplexing (TDM) scheme can be adopted, whereby access to the shared frequency band is split into different sets of TDM timeslots, with different time slots being available for different RATs. For example, 50 ms time slots may be defined, with the first, third, fifth, etc. time slots being assigned to an IEEE 802.11 WLAN RAT, and the second, fourth, sixth, etc. time slots being assigned to a Bluetooth RAT.
The described features generally relate to improved systems, methods, or apparatuses for beacon based time division multiplexing (TDM) synchronization for multiple radio access technology (RAT) coexistence. TDM time slots may be identified for each of the multiple RATs for use by a number of wireless communication devices, and the identified time slots may be synchronized based at least in part on a timing beacon associated with a first of the multiple RATs. The identification and synchronization of the time slots may be performed by one or more of the wireless communication devices—for example, one device may define the time slots, and that same device or a different device may transmit synchronization information via a timing beacon at a predefined time during one of the time slots.
A method for wireless communication is described. The method may include identifying time division multiplexing (TDM) time slots corresponding to a plurality of radio access technologies (RATs) for wireless communication among a plurality of devices, and synchronizing the TDM time slots based at least in part on a timing beacon associated with a first RAT of the plurality of RATs.
An apparatus for wireless communication is described. The apparatus may include a time division multiplexing (TDM) coordinator to identify TDM time slots corresponding to a plurality of radio access technologies (RATs) for wireless communication among a plurality of devices, and a synchronizer to synchronize the TDM time slots based at least in part on a timing beacon associated with a first RAT of the plurality of RATs.
A further apparatus for wireless communication is described. The apparatus may include means for identifying time division multiplexing (TDM) time slots corresponding to a plurality of radio access technologies (RATs) for wireless communication among a plurality of devices, and means for synchronizing the TDM time slots based at least in part on a timing beacon associated with a first RAT of the plurality of RATs.
A non-transitory computer-readable medium for wireless communication in a wireless device is described. The non-transitory computer readable medium may store computer-executable code for identifying time division multiplexing (TDM) time slots corresponding to a plurality of radio access technologies (RATs) for wireless communication among a plurality of devices, and also for synchronizing the TDM time slots based at least in part on a timing beacon associated with a first RAT of the plurality of RATs.
In the methods, apparatuses, and non-transitory computer-readable mediums described herein, the first RAT may be a wireless local access network (WLAN) RAT, and the timing beacon may be transmitted at a target beacon transmission time (TBTT) associated with the WLAN RAT. Also, the timing beacon may be transmitted within one of the TDM time slots assigned to the WLAN RAT. The first RAT and a second RAT of the plurality of
RATs use overlapping wireless spectrum frequency bands. The first RAT may be, for example a wireless local access network (WLAN), and the second RAT may be Bluetooth. The synchronizing of the TDM time slots may be triggered upon activation of the second RAT.
The plurality of devices may form an ad hoc network in one embodiment. In another embodiment, the plurality of devices may form a service access point (SAP)-station (STA) network, and the timing beacon may be transmitted, by a service access point of the SAP-STA network, to a station of the SAP-STA network, or the timing beacon may be received, by a station of the SAP-STA network, from a service access point of the SAP-STA network. In another embodiment, the plurality of devices may form a WiFi peer-to-peer (P2P) network, and the timing beacon may be transmitted, by a group owner (GO) of the WiFi P2P network, to a P2P client of the WiFi P2P network, or the timing beacon may be received, by a P2P client of the WiFi P2P network, from a group owner (GO) of the WiFi P2P network.
Clock drift in one of the plurality of devices may be monitored, and the TDM time slots may be resynchronized if the clock drift is greater than a predefined threshold. Also, a timing synchronization function (TSF) may be completed among the plurality of devices prior to synchronizing the TDM time slots.
The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description only, and not as a definition of the limits of the claims.
A further understanding of the nature and advantages of the present invention may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
The described features generally relate to improved systems, methods, apparatus, and computer program products for beacon-based time division multiplexing (TDM) synchronization for multiple radio access technology (RAT) coexistence. A number of wireless communication devices may use multiple RATs having partially or fully overlapping wireless spectrum frequency bands. Because of the possibility of interference by transmissions in the overlapping bands by coexisting radios on the same device, individual wireless communication devices may define TDM time slots during which different RATs may transmit and receive over the overlapping wireless spectrum frequency bands. The lengths of the TDM time slots allocated to each RAT traditionally vary across vendors and wireless device types. Thus, when multiple wireless devices of different types or manufactured by different vendors are connected to the same basic service set (BSS) or independent basic service set (IBSS), the TDM time slots of the wireless devices may be misaligned. For example, one of the wireless devices may transmit using WiFi while a second of the wireless devices transmits over the same band using Bluetooth. This misalignment may result in wireless devices that belong to the same network interfering with each other's transmissions, which may degrade throughput and performance for the wireless devices.
In light of these and other issues, the present disclosure provides a mechanism by which coexistence TDM time slots can be synchronized across multiple wireless devices belonging to the same network or Basic Service Set (BSS). Specifically, a timing beacon associated with a first of the RATs may be transmitted by one of the wireless devices, and the other wireless devices may receive the transmitted timing beacon to align their TDM time slots with the TDM time slots of the device that transmitted the timing beacon. In this manner, the devices may use multiple RATs to wirelessly communicate while at the same reducing or eliminating the interference associated with otherwise potentially overlapping TDM time slots.
The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various embodiments may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to certain examples may be combined in other examples.
Referring first to
Each of the wireless communication devices 115, which may also be referred to as stations (STAs), mobile stations (MSs), mobile devices, access terminals (ATs), user equipments (UEs), subscriber stations (SSs), client devices, or subscriber units, may associate and communicate with other wireless communication devices 115 via wireless communication links 125. A wireless communication device 115 can be within range of more than one wireless communication device 115 and can therefore associate with one or multiple wireless communication devices 115 at different times, or at the same time. While
Each wireless communication link 125 may be based on a radio access technology (RAT). Some wireless communication links 125 may implement a WLAN radio and baseband protocol including physical and MAC layers implementing the IEEE 802.11 family of standards, including, but not limited to, 802.11b, 802.11g, 802.11a, 802.11n, 802.11ac, 802.11 ad, 802.11 ah, etc. Other wireless communication links 125 may implement other RATs, such as Bluetooth, or generally any wireless personal area network (WPAN). Other wireless communication links 125 may be based on cellular RATs, such as long term evolution (LTE) or another cellular RAT, operating in an unlicensed band shared by the first and second RATs.
WLAN-based communication links 125 in the wireless communication network 100 may include Wi-Fi Direct connections, connections established by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, and other peer-to-peer (P2P) group connections.
For example, a first wireless communication device 115 may act as a group owner (GO) to provide service to a second wireless communication device 115 via a direct wireless communication link 125. In this scenario, the first wireless communication device 115 may function similar to an AP to the second wireless communication device 115, and the second wireless communication device 115 may be referred to as a P2P client. As another example, an ad hoc network may be formed among two or more of the wireless communication devices 115, which together may form an independent basic service set (IBSS). As still another example, one of the wireless communication devices 115 may act as a service access point (SAP), with the other wireless access points being stations (STA), forming what may be referred to as a SAP-STA network.
Bluetooth RAT based links 125 may include an object push profile (OPP) service, pairing communications, service discovery protocol (SDP) communications, and so forth. And direct wireless communication links 125 based on other RATs may similarly take many different forms, including for data transfer, control (e.g., for peripheral devices), and so forth.
As mentioned above, two or more of the RATs used in the wireless communication network 100 between wireless communication devices 115 may use partially overlapping frequency bands. For example, both IEEE 802.11 WLAN RAT based links 125 and Bluetooth RAT based links 125 may utilize a 2.4 GHz band for transmissions. Similarly, an IEEE 802.11 WLAN RAT based link 125 and an LTE-U RAT based link 125 may both utilize a 5 GHz band for transmissions. In order to accommodate the coexistence of the multiple RATs with partially or fully overlapping frequency bands, time division multiplexing (TDM) may be employed in order to allocate certain time slots to certain RATs. TDM time slots may be defined such that during a first set of time slots, the devices 115 may communicate using a first RAT, and during a second set of time slots, the devices 115 may communicate using a second RAT. Additional time slots may further be defined for third and fourth RATs, if desired. In the example with only two different RATs, alternating 50 milliseconds (ms) time slots may be assigned to the first and second RATs, such that during the first, third, fifth, etc. time slots, only the first RAT is used by the devices 115 to communicate, and during the second, fourth, sixth, etc. time slots, only the second RAT is used by the devices 115 to communicate.
The TDM time slots may be identified at the wireless communication devices 115 in one of several manners. For example, each device 115 may determine lengths for the TDM timeslots and assign certain RATs to certain time slots. As another example, the TDM time slots may be defined in a standard or by another entity. The lengths of the time slots may be configurable such that, depending on traffic or quality of service (QoS) needs of each RAT, the time slots for one RAT may be longer than the time slots for another RAT.
Even when using such a TDM access scheme, however, transmissions associated with different RATs may still interfere with one another if the TDM time slots are not properly aligned among the multiple devices 115, which may be the case in peer-to-peer (P2P) and other network configurations in which different wireless communication devices attempt to separately select the TDM time slots. For example, and referring now to the timing diagram 200 in
In the configuration illustrated in
As illustrated in
It will be appreciated that while
Turning now to the timing diagram 300 shown in
The timing beacons 305, 310 may be used to synchronize the TDM time slots in one of several manners. In some instances, the timing beacons 305, 310 may include explicit information elements (IE) or other control signaling indicating to the devices 115-a-1, 115-a-2 one or more parameters needed for synchronization of the TDM time slots. In other instances, the devices 115-a-1, 115-a-2 may infer one or more parameters needed for synchronization from the timing beacons 305, 310 (such as the time at which the timing beacon is received, beacon length parameters in the timing beacon, and so forth), and thus the timing beacons 305, 310 may not include explicit synchronization information. In either example, the timing beacons 305, 310 may be associated with a specific RAT, such as the WLAN RAT. When associated with the WLAN RAT, the timing beacons 305, 310 may include basic information concerning a basic services set (BSS) or independent basic services set (IBSS) associated with the WLAN, such as whether traffic is pending for each of the devices 115-a-1, 115-a-2, beacon intervals, time stamp information, capability information, identifying information, other administrative information, and so forth.
The timing beacons 305, 310 can thus be conventional timing beacons sent by a group owner (GO) or access point (AP) of a WLAN network in some embodiments. Alternatively, however, the timing beacons 305, 310 may be separate from the conventional WLAN timing beacons, and may be specific to the present disclosure and the synchronization of TDM time slots among multiple wireless communication devices 115-a-1, 115-a-2. Generally speaking the timing beacons 305, 310 may be associated with any of the RATs in use in the network, and may be conventional timing beacons (with or without modifications) or new timing beacons defined just for the purpose of synchronizing TDM time slots as described herein.
Again referring to the example in which the timing beacons 305, 310 are associated with the WLAN RAT, in one implementation, the timing beacons 305, 310 may be transmitted at a target beacon transmission time (TBTT) of the WLAN RAT. The TBTT may be within a TDM time slot assigned to the WLAN RAT, and may be near the beginning of WLAN RAT TDM time slots 210, 220. For example, if each TDM time slot is 50 ms, then the TBTT may be 5 ms after the beginning of the WLAN RAT TDM slot, which may provide a small margin before the timing beacon is sent in order to cause the transmission of the timing beacon to be covered by the WLAN RAT TDM slot, which in turn may help avoid a stalled or missed timing beacon transmission. In other examples, however, the timing beacon may be transmitted in a time slot associated with a different RAT, or in a different position within the time slot associated with the WLAN RAT. Also, broadcast/multicast packets (including dynamic host configuration protocol (DHCP) packets) may be transmitted immediately following the timing beacon in some embodiments, which may reduce the likelihood of these packets from needing to be retransmitted.
As illustrated in
Comparing
Referring to
At block 415, the devices 115 may monitor for changes that trigger resynchronization—for example, if clock drift greater than a predefined threshold is detected in one of the devices, if a new device joins the network 100, if there are reports of interference or congestion among the different RATs, and so forth. In some examples, one change that may trigger resynchronization may be the expiration of a timer, which may cause the TDM time slots to be periodically resynchronized regardless of any other events. If the devices 115 detect no changes triggering the resynchronization, then the devices 115 may continue to monitor for changes at block 415. If the devices 115 do detect a change triggering resynchronization, the TDM time slots may again be synchronized at block 410 in a manner similar to that described above.
The components of the device 115-b may, individually or collectively, be implemented using application-specific integrated circuits (ASICs) adapted to perform some or all of the applicable functions in hardware. Alternatively, the functions may be performed by other processing units (or cores), on integrated circuits. In other examples, other types of integrated circuits may be used (e.g., Structured/Platform ASICs, Field Programmable Gate Arrays (FPGAs), and other Semi-Custom ICs), which may be programmed in any manner known in the art. The functions of each component may also be implemented, in whole or in part, with instructions embodied in a memory, formatted to be executed by general or application-specific processors.
The receiver 505 may receive information such as packets, user data, or control information associated with various information channels (e.g., control channels, data channels, etc.). The receiver 505 may thus receive a timing beacon transmitted by another wireless device, other information regarding TDM time slots, and so forth.
Information received by the receiver 505 may be passed on to the coexistence manager 510, and to other components of the device 115-b. The coexistence manager 510 may be configured to identify TDM time slots corresponding to a number of RATs for wireless communication with other devices, and also to synchronize the TDM time slots based on a timing beacon associated with a first of the RATs.
The transmitter 515 may transmit signals received from other components of the device 115-b. For example, the transmitter 515 may transmit a timing beacon to other wireless communication devices.
In some examples, each device within a network (e.g. the network 100 in
The network monitor 605 of the coexistence manager 510-a in
The TDM coordinator 610 of the coexistence manager 510-a in
The synchronizer 615 of the coexistence manager 510-a in
The timing beacon controller 620 of the coexistence manager 510-a in
In those embodiments in which multiple wireless communication devices form an ad hoc or IBSS network, the timing beacon controller 620 may be configured to attempt to transmit the timing beacon at a target beacon transmission time (TBTT) to other devices, and also configured to listen for transmitted timing beacons from others of the plurality of devices. In this manner, each device may contend at the TBTT to send the timing beacon, while also listening for possible timing beacons sent by other devices.
In those embodiments in which multiple wireless communication devices form a SAP-STA network, the timing beacon controller 620 may be configured to transmit the timing beacon to stations of the SAP-STA network when the device 115-c is a SAP of the SAP-STA network. The timing beacon controller 620 may additionally or alternatively be configured to receive the timing beacon from a SAP when the device 115-c is a STA of the SAP-STA network.
In those embodiments in which multiple wireless communication devices form a WiFi peer-to-peer (P2P) network, the timing beacon controller 620 may be configured to transmit the timing beacon to P2P clients of the WiFi P2P network when the device 115-c is a group owner (GO). The timing beacon controller 620 may additionally or alternatively be configured to receive the timing beacon from a GO when the device 115-c is a P2P client.
Turning to
The wireless communication device 115-d-1 may include a first antenna 705 and first transceiver 710 for sending or receiving transmissions based on a first RAT (e.g., for communications with a second wireless communication device 115-d-2). The wireless communication device 115-d-1 in
The memory 730 may include RAM and ROM. The memory 730 may store computer-readable, computer-executable software (SW) code 735 containing instructions that are configured to, when executed, cause the processor 725 or other components of the device 115-d-1 to perform various functions described herein. Alternatively, the software code 735 may not be directly executable by the processor 725 but may be configured to cause the computer (e.g., when compiled and executed) to perform functions described herein.
The processor 725 may include an intelligent hardware device, e.g., a CPU, a microcontroller, an ASIC, etc. The processor 725 may process information received from other components of the device 115-d-1 and provide results to other components of the device 115-d-1.
The wireless communication device 115-d-1 illustrated in
According to the architecture of
The components of the device 115-d-1 may be configured to implement aspects discussed above with respect to
At block 805, the method 800 may include identifying time division multiplexing (TDM) time slots corresponding to a plurality of radio access technologies (RATs) for wireless communication among a plurality of devices. At block 820, the method 800 may include synchronizing the TDM time slots among the plurality of devices based on a timing beacon associated with a first of the plurality of RATs.
Thus, the method 800 may provide for wireless communication. It should be noted that the method 800 is just one implementation and that the operations of the method 800 may be rearranged or otherwise modified such that other implementations are possible.
At block 905, the method 900 may include identifying a new device in a wireless network, the wireless network employing a first radio access technology (RAT). At block 910, the method 900 may include completing a timing synchronization function (TSF) associated with the wireless network—for example, all of the devices in the wireless network may complete the TSF. At block 915, the method 900 may include identifying a second RAT being activated for use in the wireless network by one or more of the devices in the network.
At block 920, the method 900 may include identifying time division multiplexing (TDM) time slots corresponding to the first and second RATs for wireless communication within the wireless network. At block 925, the method 900 may include synchronizing the TDM time slots based at least in part on a timing beacon associated with the first RAT.
At block 930, the method 900 may include monitoring the synchronized TDM time slots for clock drift, and at block 935, the method 900 may include resynchronizing the TDM time slots if the clock drift monitored at block 930 is greater than a predefined threshold.
Thus, the method 900 may provide for wireless communication. It should be noted that the method 900 is just one implementation and that the operations of the method 900 may be rearranged or otherwise modified such that other implementations are possible.
Aspects from both of the methods 800, 900 may be combined. It should be noted that the methods 800, 900 are just example implementations, and that the operations of the methods 800, 900 may be rearranged or otherwise modified such that other implementations are possible.
The detailed description set forth above in connection with the appended drawings describes examples and does not represent the only examples that may be implemented or that are within the scope of the claims. The terms “example” and “exemplary,” when used in this description, mean “serving as an example, instance, or illustration,” and not “preferred” or “advantageous over other examples.” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, well-known structures and apparatuses are shown in block diagram form in order to avoid obscuring the concepts of the described examples.
Information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.
The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an ASIC, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The functions described herein may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. If implemented in software executed by a processor, the functions may be stored on or transmitted over as instructions or code on a computer-readable medium. Other examples and implementations are within the scope and spirit of the disclosure and appended claims. For example, due to the nature of software, functions described above can be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations. As used herein, including in the claims, the term “or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items (for example, a list of items prefaced by a phrase such as “at least one of” or “one or more of”) indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).
Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium may be any available medium that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, computer-readable media can comprise RAM, ROM, EEPROM, flash memory, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above are also included within the scope of computer-readable media.
The previous description of the disclosure is provided to enable a person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not to be limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.
