Patent Application
20120057575
1. Field
Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to simultaneous beam training of multiple pairs of wireless nodes.
2. Background
In order to address the issue of increasing bandwidth requirements that are demanded for wireless communications systems, different technologies are being developed to allow multiple wireless nodes to communicate by sharing the channel resources while achieving high data throughputs. These technologies have been adopted in several emerging wireless communications standards, such as the family of Institute of Electrical Engineers (IEEE) 802.11 wireless communication standards and the family of IEEE 802.15 wireless communication standards.
The IEEE 802.11 denotes a set of Wireless Local Area Network (WLAN) air interface standards developed by the IEEE 802.11 committee for short-range communications (e.g., tens of meters to a few hundred meters). One example includes IEEE 802.11ad to support 60 GHz operation, which is sometimes referred as “Extremely High Throughput.”
Another example protocol for high throughput systems includes the IEEE 802.15.3c Media Access Control (MAC) protocol for wireless personal area networks (PAN). The 802.15.3c MAC protocol provides dedicated time-intervals for each pair of wireless nodes in a communications system to train with respect to each other, prior to data communication. However, as the number of peer-to-peer communications grows, this mechanism suffers from increased training overhead.
Certain aspects of the present disclosure provide a method for wireless communications. The method generally includes selecting, by a first apparatus, a training sequence from a plurality of training sequences to perform beam training with a second apparatus simultaneously with beam training of at least one other pair of apparatuses, and performing the beam-training with the second apparatus using the selected training sequence simultaneously with the beam training of the other pair of apparatuses.
Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes a first circuit configured to select a training sequence from a plurality of training sequences to perform beam training with another apparatus simultaneously with beam training of at least one other pair of apparatuses, and a second circuit configured to perform the beam training with the other apparatus using the selected training sequence simultaneously with the beam training of the other pair of apparatuses.
Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes means for selecting a training sequence from a plurality of training sequences to perform beam training with another apparatus simultaneously with beam training of at least one other pair of apparatuses, and means for performing the beam training with the other apparatus using the selected training sequence simultaneously with the beam training of the other pair of apparatuses.
Certain aspects provide a computer-program product for wireless communications. The computer-program product includes a computer-readable medium comprising instructions executable to select, by a first apparatus, a training sequence from a plurality of training sequences to perform beam training with a second apparatus simultaneously with beam training of at least one other pair of apparatuses, and perform the beam training with the second apparatus using the selected training sequence simultaneously with the beam training of the other pair of apparatuses.
Certain aspects of the present disclosure provide a wireless node. The wireless node generally includes at least one antenna, a first circuit configured to select a training sequence from a plurality of training sequences to perform beam training with another wireless node simultaneously with beam training of at least one other pair of wireless nodes, a second circuit configured to perform the beam training with the other wireless node using the selected training sequence simultaneously with the beam training of the other pair of wireless nodes, and a transmitter configured to transmit via the at least one antenna a plurality of signals constructed based on the selected training sequence.
So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.
Various aspects of the disclosure are described more fully hereinafter with reference to the accompanying drawings. This disclosure may, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed herein, whether implemented independently of or combined with any other aspect of the disclosure. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.
Although particular aspects are described herein, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to particular benefits, uses or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks and transmission protocols, some of which are illustrated by way of example in the figures and in the following description of the preferred aspects. The detailed description and drawings are merely illustrative of the disclosure rather than limiting, the scope of the disclosure being defined by the appended claims and equivalents thereof.
Several aspects of a wireless communications system will now be presented. The wireless communications system may support any number of apparatuses. In this example, each apparatus is implemented as a wireless node. A wireless node may be a station (STA), or other suitable node.
The wireless communications system may be configured to support multiple STAs employingMultiple-Input and Multiple-Output (MIMO) technology supporting any suitable wireless technology, such as Orthogonal Frequency Division Multiplexing (OFDM). An OFDM system may implement IEEE 802.11, IEEE 802.15, or some other air interface standard. Other suitable wireless technologies include, by way of example, Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), or any other suitable wireless technology, or any combination of suitable wireless technologies. A CDMA system may implement IS-2000, IS-95, IS-856, Wideband-CDMA (WCDMA), or some other suitable air interface standard. A TDMA system may implement Global System for Mobile Communications (GSM) or some other suitable air interface standard. As those skilled in the art will readily appreciate, the various aspects of this disclosure are not limited to any particular wireless technology and/or air interface standard. The various concepts presented throughout this disclosure may also be extended to short range radio technology, such as Ultra-Wide Band (UWB), or some other short range air interface standard such as Bluetooth. The actual wireless technology and air interface standard employed for any particular communications system will depend on the specific application and the overall design constraints imposed on the system. The various concepts presented throughout this disclosure are equally applicable to a wireless communications system employing other wireless technologies and/or air interface standards.
The wireless communications system may support any number of APs distributed throughout a geographic region. A STA, which may be fixed or mobile, may engage in peer-to-peer communications with other STAs. Examples of STAs include a mobile telephone, laptop computer, a personal digital assistant (PDA), a mobile digital audio player, a mobile game console, a digital camera, a digital camcorder, a mobile audio device, a mobile video device, a mobile multimedia device, a smart phone, a tablet, a television display, a flip-cam, a security video camera, a digital video recorder (DVR), a set top box kiosk, or a media center, or any other suitable device capable of supporting wireless communications. A STA may utilize the backhaul services of an access point (AP) to gain access to a larger network (e.g., Internet). According to aspects of the present disclosure, a STA may operate in accordance with the IEEE 802.11 interface standard, or alternatively in accordance with the IEEE 802.15 interface standard.
A STA may be referred to by those skilled in the art by different nomenclature. By way of example, a STA may be referred to as a user terminal, a mobile station, a subscriber station, a wireless device, a terminal, an access terminal, a node, or some other suitable terminology. The various concepts described throughout this disclosure are intended to apply to all suitable apparatuses regardless of their specific nomenclature.
Various aspects of an apparatus will now be presented with reference to
The wireless interface 102 may comprise a transceiver having a transmitter and receiver function to support two-way communications over the wireless medium. Alternatively, the wireless interface 102 may be configured as a transmitter or receiver to support one-way communications. In the detailed description that follows, a wireless interface may be described as a transmitter or a receiver to illustrate a particular aspect of the invention. Such a reference does not imply that the wireless interface is incapable of performing both transmit and receive operations.
The wireless interface 102 may support different air interface protocols. By way of example, the wireless interface 102 may comprise a 60 GHz radio to support IEEE 802.11 ad (Extremely High Throughput), or some other suitable air interface protocol. The wireless interface 102 may also be configured to implement the physical layer by modulating wireless signals and performing other radio frequency (RF) front end processing. Alternatively, the physical layer processing function may be performed by the processing system 104.
The wireless interface 102 is shown as a separate entity. However, as those skilled in the art will readily appreciate, the wireless interface 102, or any portion thereof, may be integrated into the processing system 104, or distributed across multiple entities within the apparatus 100.
The processing system 104 may be implemented with one or more processors. The one or more processors may be implemented with any combination of general-purpose microprocessors, microcontrollers, a Digital Signal Processors (DSP), Field Programmable Gate Arrays (FPGA), Programmable Logic Devices (PLD), controllers, state machines, gated logic, discrete hardware components, or any other suitable entities that can perform calculations or other manipulations of information.
The processing system 104 may also comprise machine-readable media for storing software. Software shall be construed broadly to mean any type of instructions, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Instructions may comprise code (e.g., in source code format, binary code format, executable code format, or any other suitable format of code). The instructions, when executed by the one or more processors, may cause the processing system 104 to perform the various functions described below, as well as other protocol processing functions (e.g., data link layer processing).
Machine-readable media may comprise storage integrated into one or more of the processors. Machine-readable media may also comprise storage external to the one or more processor, such as a Random Access Memory (RAM), a flash memory, a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable PROM (EPROM), registers, a hard disk, a removable disk, a CD-ROM, a DVD, or any other suitable storage device. In addition, machine-readable media may comprise a transmission line or a carrier wave that encodes a data signal. Those skilled in the art will recognize how best to implement the described functionality for the processing system.
First, the STA-1 may transmit a Walsh or a Golay sequence (trainingSequenceID) of length L serially across AT transmit beam patterns (e.g., directions) supported by the STA-2, NR times for each transmit beam pattern, where NR is the number of receive beam patterns supported by the STA-2 (step 210). Such a transmission can be referred to as a “double-lighthouse” transmission. Assuming AT and NR are each 64, a system chip-rate of 1.7 Gps, a Walsh/Golay chip duration of 0.6 ns, and L=64, the total transmission time may be approximately 157 us (0.6 ns*64*64*64).
The training may be performed during a service period (i.e., allocation period) assigned by another wireless node. The service/allocation period may be a dedicated period of time assigned by another wireless node for one or more pairs of wireless terminals to perform training. In one configuration, the training may be performed using a code sequence selected from a set of code sequences that are also being used by one or more other pairs to perform training. That is, the STA-1 may select a code sequence from a set of code sequences. The set of code sequences may be also used by other pairs to perform training The selection may be random or predetermined through an algorithm. In another configuration, the training may be performed using a code sequence assigned by another wireless node (e.g., AP). In such a configuration, the code sequence may not be used by the one or more other pairs to perform training. That is, the code sequence transmitted by the STA-1 may be selected by another wireless node, such as an access point, and that code sequence may not be used by other pairs to perform training. As discussed supra, the code sequence may be a Walsh sequence or a Golay sequence.
For 60 GHz short-range PAN type networks, typically there are not more than 16 active stations per AP. As such, at any given peer-to-peer training time, no more than eight pairs of STAs may engage in peer-to-peer training.
The STA-2 may receive the sequence from the STA-1 and estimate preferred (e.g., the best) transmit and receive beam patterns for STA-1 to STA-2 communication based on Walsh/Golay correlation of the received waveform using the trainingSequenceID. As such, after step 210, the STA-2 may know the preferred transmit and receive beam patterns for the STA-1 to STA-2 communication.
Second, the STA-2 may transmit a Walsh or a Golay sequence (specified by trainingSequenceID) serially across NT transmit beam patterns supported by the STA-2, AR times for each beam pattern (double-lighthouse), where AR is the number of receive beam patterns supported by the STA-1 (step 220). Assuming NT and AR are each 64, a system chip-rate of 1.7 Gps, a Walsh/Golay chip duration of 0.6 ns, and L=64, the total transmission time may be approximately 157 us (0.6 ns*64*64*64).
The STA-1 may receive the sequence from the STA-2 and estimate preferred transmit and receive beam patterns for STA-2 to STA-1 communication based on Walsh/Golay correlation of the received waveform using the trainingSequenceID. As such, after step 220, the STA-1 may know the preferred transmit and receive beam patterns for the STA-2 to STA-1 communication.
Third, the STA-2 may then transmit a sequence corresponding to a 6-bit transmit beam index to the STA-1 (step 230). The index may indicate a preferred transmit beam pattern for STA-1 to STA-2 communication (i.e., one of the AT transmit beam patterns). The STA-2 may select a length L Walsh or Golay sequence corresponding to the 6-bit index. The STA-2 may scramble the length L sequence with a seed equal to the trainingSequenceID. In an aspect, the scrambling sequence generator may be in accordance with the IEEE 802.15.3c specification. The STA-2 may transmit this sequence serially across NT transmit beam patterns, only once for each transmit beam pattern. Because the STA-1 may know the preferred receive beam pattern for STA-2 to STA-1 communication (i.e., one of the AR receive beam patterns), the STA-1 may use its preferred receive beam pattern to receive the sequence. This transmission can be referred to as a “single-lighthouse” transmission. Assuming L is 256, the total transmission time may be approximately 10 us (0.6 ns*256*64). As such, after step 230, the STA-1 may know the preferred transmit and receive beam patterns for STA-2 to STA-1 communication and the preferred transmit beam pattern for STA-1 to STA-2 communication.
Fourth, the STA-1 may transmit a sequence corresponding to a 6-bit transmit beam index to the STA-2 (step 240). The index may indicate a preferred transmit beam pattern for STA-2 to STA-1 communication (i.e., one of the NT transmit beam patterns). The STA-1 may select a length L Walsh or Golay sequence corresponding to the 6-bit index. The STA-1 may scramble the length L sequence with a seed equal to the trainingSequenceID. In an aspect, the scrambling sequence generator may be in accordance with the 802.15.3c specification. The STA-1 may transmit the sequence through the preferred transmit beam pattern for STA-1 to STA-2 communication (i.e., one of the AT transmit beam patterns). Because the STA-2 may know the preferred receive beam pattern for STA-1 to STA-2 communication, the STA-2 may use its preferred receive beam pattern (i.e., one of the NR receive beam patterns) to receive the sequence. Assuming L equals 256, the total transmission time may be approximately 150 ns (0.6 ns*256).
In one configuration, the apparatus 300 may comprise means for generating a first signal for transmission to a wireless node to enable the wireless node to determine a first preferred beam pattern; means for determining a second preferred beam pattern from a second signal received from the wireless node; and means for communicating with the wireless node through at least one of the first or second preferred beam pattern. The aforementioned means is the processing system 104 configured to perform the functions of the aforementioned means.
According to certain aspects, periodic beam training may be required to achieve multi-Gbps throughput in 60 GHz transmission band (i.e., for IEEE 802.11ad interface protocol, referred also as “Extremely High Throughput” protocol) to account for blockage, movement, change of orientation, and so on. Typically, STAs may utilize dedicated service (time) periods to beam-train in order to prevent disruption to other 60 GHz traffic. The resulting beam training overhead may be significant for 60 GHz network with multiple STAs, e.g., for a network of eight STAs in a conference room. Methods and apparatus are proposed in the present disclosure to reduce this beam-training overhead.
In order to reduce the training overhead, multiple pairs of STAs may be allowed to perform beam training simultaneously. Each pair of STAs may utilize a different training sequence in order to mitigate interference. In an aspect, the different training sequences may be based on different Golay codes, where multiple Golay codes with good cross-correlation properties may be generated using the same hardware.
In an aspect, the cyclic cross-correlation 504 illustrated in
Aspects of the present disclosure confirm that simultaneous training of two pairs of devices may reduce the beam-training overhead by approximately 50%. Performances of simultaneous beam training of two and three pairs of STAs are provided in following paragraphs of the detailed description.
In an aspect of the present disclosure, channels can be generated using the TGad (Task Group ad) Conference Room channel model. A training sequence can be transmitted across each of transmission beams in a random order. For example, there can be 19 transmission beams of 60° half power bandwidth (HPBW) covering the half space for z>0. The training sequence may be received in an omni-directional mode (covering z>0) and using a simple correlator detector. The receiver may select a preferred transmission beam by comparing the strength of the received training sequences across all beam directions. A random delay of 0-20 chips can be added to model in-room propagation delays. In an exemplary case, performance results are averaged over 100 channel realizations and 10 noise realizations with beam-ordering per channel realization.
Certain aspects of the present disclosure support simultaneous beam training of multiple pairs of STAs configured to operate according to the IEEE 802.11ad interface protocol. The simultaneous beam training may be overlaid on any beam training protocol with transmit/receive sweep. As illustrated in
In one aspect of the present disclosure, STAs may be configured to align transmit/receive sector sweeps during beam training
In another aspect of the present disclosure, STAs may not be required to align their transmit/receive sector sweeps during the beam training process. This approach may be applied, for example, for the Wireless Gigabit Alliance (WGA) interface protocol.
In an aspect of the present disclosure, selection of the training sequence may be based on an index of the training sequence assigned by an access point of the wireless communications system. In another aspect, the selection may be based on STA identification. In yet another aspect, the selection may be based on a network identifier. Further, the training sequence may be selected randomly from the plurality of training sequences. Finally, the training sequence may be selected based on an assigned priority relative to other STAs in the wireless communications system. The priority may be identified as a flag in an assignment message transmitted from the access point.
In an aspect of the present disclosure, the beam training may comprise transmitting a plurality of signals constructed based on the selected training sequence. The transmission of the plurality of signals may be performed in a predetermined period that may be specified by another STA or the access point. This predetermined period may comprise a plurality of slots, and, in the case of time-aligned simultaneous beam-training illustrated in
For supporting the time-aligned beam training, the plurality of training sequences may be designed such that a zero cross-correlation zone associated with the training sequences may be greater than or equal to a defined number of chip periods. In one aspect, the zero cross-correlation zone may be equal to at least one quarter of a length of the training sequence. In another aspect, a zero cross-correlation zone of a pair of training sequences from the plurality of training sequences may be equal to a quarter of the length of training sequence.
In order to support the non-aligned beam training illustrated in
The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component(s) and/or module(s), including, but not limited to a circuit, an application specific integrate circuit (ASIC), or processor. Generally, where there are operations illustrated in Figures, those operations may have corresponding counterpart means-plus-function components with similar numbering. For example, operations 1100 illustrated in
As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure), ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.
As used herein, a phrase referring to “at least one of a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
The various operations of methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software component(s), circuits, and/or module(s). Generally, any operations illustrated in the Figures may be performed by corresponding functional means capable of performing the operations.
For example, the means for selecting may comprise an application specific integrated circuit, e.g., the processing system 104 from
The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), 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 commercially available 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, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm described in connection with the present disclosure may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in any form of storage medium that is known in the art. Some examples of storage media that may be used include random access memory (RAM), read only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM and so forth. A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. A storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.
The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.
The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media include 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 computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, 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 in the form of instructions or data structures and that can be accessed by a computer. 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 (IR), 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. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media). In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.
Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging material.
Software or instructions may also be transmitted over a transmission 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 transmission medium.
Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.
It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.
While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
The present application for patent claims benefit of U.S. Provisional Patent Application Ser. No. 61/314,420, entitled, “SIMULTANEOUS BEAM TRAINING,” filed Mar. 16, 2010, and assigned to the assignee hereof and hereby expressly incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61314420 | Mar 2010 | US |
