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    • 专利摘要:
    construction of long training field sequences of very high transmission capacity. certain aspects of the present disclosure relate to techniques for constructing vht long-forming (ltf) field sequence with high transmission capacity per 80 mhz channel based on two 40 mhz ltfs of the ieee 802.11n or 802.11a standard, or ltfs frame of ieee802.11a standard.
    公开号:BR112012000857B1
    申请号:R112012000857-9
    申请日:2010-07-13
    公开日:2021-08-10
    发明作者:Didier Johannes Richard Van Nee；Lin Yang；Hemanth Sampath
    申请人:Qualcomm Incorporated；
    IPC主号:
    专利说明:

    Priority Claim
    [001] This patent application claims the benefit of Provisional Application Serial No. 61/226,615 filed on July 17, 2009, and assigned to the assignee hereof and expressly incorporated by reference. Field of Invention
    [002] Certain aspects of the present disclosure generally relate to wireless communications and, more particularly, to the construction of a long training field sequence (LTF) within a preamble. Description of Prior Art
    [003] Specifications established by the Institute of Electrical and Electronics Engineers (IEEE) 802.11 Wide Local Area Network (WLAN) standards body for transmissions based on very high transmission capacity (VHT) approach using a carrier frequency of 5 GHz (ie the IEEE 802.11ac specification), or using a carrier frequency of 60 GHz (ie the IEEE 802.11ad specification) in order to aggregate transmission capacities greater than 1 Gigabits per second. One of the most conducive technologies for the 5GHz VHT specification is a larger channel bandwidth, which links two 40MHz channels to 80MHz bandwidth, thus doubling the physical layer data rate (PHY) with negligible increase in cost compared to the IEEE 802.11n standard.
    [004] A VHT Long Training Ground (LTF) is a part of a broadcast preamble, and can be used on one side of the receiver to estimate underlying multiple-input and underlying multiple-output wireless channel characteristics. Methods are proposed in the present disclosure to construct the VHT-LTF sequence while providing a low peak/average power ratio (PAPR) on one side of the transmitter. Invention Summary
    [005] Certain aspects of the present disclosure support a method for wireless communications. The method generally includes constructing a long training field (LTF) sequence, combining a plurality of interpolation sequences and one or more other sequences repeated several times in an effort to reduce (or possibly minimize) a power ratio. peak/average (PAPR) during a transmission of the constructed LTF sequence, and transmitting the constructed LTF sequence over a wireless channel using a bandwidth of a first size.
    [006] Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes a construction circuit configured to construct a long training field (LTF) sequence, combining a plurality of interpolation sequences and one or more other sequences repeated several times in an effort to reduce (or, possibly, minimize) a peak/average power ratio (PAPR) during a transmission of the constructed LTF sequence, and a transmitter configured to transmit the constructed LTF sequence over a wireless channel using a bandwidth of a first size.
    [007] Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes means for constructing a long training field (LTF) sequence by combining a plurality of interpolation sequences and one or more other sequences repeated several times in an effort to reduce (or possibly minimize) a relationship. peak/average power (PAPR) during a transmission of the constructed LTF sequence, and means for transmitting the constructed LTF sequence over a wireless channel using a bandwidth of a first size.
    [008] Certain aspects of the present disclosure provide a computer program product for wireless communications. The computer program product includes a computer-readable medium comprising executable instructions for constructing a long training field (LTF) sequence, combining a plurality of interpolation sequences and one or more other sequences repeated several times in an effort to reduce ( or possibly minimizing) a peak/average power ratio (PAPR) during a transmission of the constructed LTF sequence, and transmitting the constructed LTF sequence over a wireless channel using a bandwidth of a first size.
    [009] Certain aspects of the present disclosure provide for a wireless node. The wireless node generally includes at least one antenna, a construction circuit configured to construct a long training field (LTF) sequence, combining a plurality of interpolation sequences and one or more other sequences repeated several times in an effort. to reduce (or possibly minimize) a peak/average power ratio (PAPR) during a transmission of the constructed LTF sequence, and a transmitter configured to transmit through the antenna, at least one LTF sequence constructed over a wireless channel using a bandwidth of a first size.
    [0010] Certain aspects of the present disclosure support a method for wireless communications. The method generally includes constructing a long training field (LTF) sequence, combining a plurality of interpolation sequences with LTF symbol values associated with at least one of the IEEE 802.11n standard or the IEEE 802.11a standard, where the LTF symbol values cover at least a portion of the bandwidth of a first size, and each of the LTF symbol values is repeated one or more times for different subcarriers, rotating symbol phases of the LTF sequence by bandwidth of the first size, in an effort to reduce (or possibly minimize) a peak-to-average power ratio (PAPR) during an LTF stream transmission, and transmit the LTF stream over a wireless channel using a bandwidth of one second size.
    [0011] Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes a first circuit configured to construct a long training field (LTF) sequence, combining a plurality of interpolation sequences with LTF symbol values associated with at least one of the IEEE 802.11n standard or the IEEE standard 802.11a, wherein the LTF symbol values cover at least a portion of the bandwidth of a first size, and each of the LTF symbol values is repeated one or more times for different subcarriers, a second circuit configured to rotate phases of LTF sequence symbols per bandwidth of the first size, in an effort to reduce (or possibly minimize) a peak-to-average power ratio (PAPR) during a transmission of the LTF sequence, and a transmitter configured to transmit the LTF sequence over a wireless channel using a bandwidth of a second size.
    [0012] Certain aspects of the present disclosure provide an apparatus for wireless communications. The apparatus generally includes means for constructing a long training field (LTF) sequence by combining a plurality of interpolation sequences with LTF symbol values associated with at least one of the IEEE 802.11n standard or the IEEE 802.11a standard, wherein the LTF symbol values cover at least a portion of the bandwidth of a first size, and each of the LTF symbol values is repeated one or more times for different subcarriers, means for rotating the symbol phases of the LTF sequence by bandwidth of the first size, in an effort to reduce (or possibly minimize) a peak-to-average power ratio (PAPR) during a transmission of the LTF sequence, and means to transmit the LTF sequence over a wireless channel using a bandwidth of a second size.
    [0013] Certain aspects of the present disclosure provide a computer program product for wireless communications. The computer program product includes a computer-readable medium comprising executable instructions for constructing a long training field (LTF) sequence by combining a plurality of interpolation sequences with LTF symbol values associated with at least one of the IEEE 802.11 standard. n or the IEEE 802.11a standard, wherein the LTF symbol values cover at least a portion of the bandwidth of a first size, and each of the LTF symbol values is repeated one or more times for different subcarriers by rotating the phases of LTF sequence symbols per bandwidth of the first size in an effort to reduce (or possibly minimize) a peak-to-average power ratio (PAPR) during a transmission of the LTF sequence, and transmit the LTF sequence over a channel wireless using a bandwidth of a second size.
    [0014] Certain aspects of the present disclosure provide for a wireless node. The wireless node generally includes at least one antenna, a first circuit configured to construct a long training field (LTF) sequence, combining a plurality of interpolation sequences with LTF symbol values associated with at least one of the pattern. IEEE 802.11n or the IEEE 802.11a Standard, wherein the LTF symbol values cover at least a portion of the bandwidth of a first size, and each of the LTF symbol values is repeated one or more times for different subcarriers, a second circuit configured to rotate LTF sequence symbol phases by bandwidth of the first size, in an effort to reduce (or possibly minimize) a peak-to-average power ratio (PAPR) during an LTF sequence transmission, and a transmitter configured to transmit through the antenna at least one LTF stream over a wireless channel using a bandwidth of a second size. Brief Description of Figures
    [0015] In order that the manner in which the above recited features of the present disclosure may be understood in detail, a more particular description, summarized above, may be considered for reference to aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the attached drawings show only some typical aspects of this disclosure and, therefore, should not be considered as limiting its scope, for the description may admit other equally effective aspects.
    [0016] Figure 1 - illustrates a diagram of a wireless communications network in accordance with certain aspects of the present disclosure.
    [0017] Figure 2 - illustrates a block diagram of an example of signal processing functions of a physical layer (PHY) of a wireless node in the wireless communications network of Figure 1 in accordance with certain aspects of the present disclosure.
    [0018] Figure 3 - illustrates a block diagram of an exemplary hardware configuration for a processing system in a wireless node in the wireless communications network of Figure 1 in accordance with certain aspects of the present disclosure.
    [0019] Figure 4 - illustrates exemplary operations for building a long training field sequence with very high transmission capacity (VHT-LTF) for 80 MHz channel, in accordance with certain aspects of the present disclosure.
    [0020] Figure 4A - illustrates exemplary components capable of performing the operations illustrated in Figure 4.
    [0021] Figure 5 - illustrates example of peak/average power ratio (PAPR) results for 80MHz LTFs designed according to a legacy-based approach in accordance with certain aspects of the present disclosure.
    [0022] Figure 6 - illustrates another example of PAPR results for 80MHz LTFs designed according to the legacy-based approach in accordance with certain aspects of the present disclosure.
    [0023] Figures 7A-7B - illustrate example PAPR results for 80MHz LTFs designed based on a first new sequence in accordance with certain aspects of the present disclosure.
    [0024] Figure 8 - illustrates preferred 80MHz LTFs designed based on the first new sequence in accordance with certain aspects of the present disclosure.
    [0025] Figures 9A-9B - illustrate example PAPR results for 80MHz LTFs designed based on a new second sequence in accordance with certain aspects of the present disclosure.
    [0026] Figure 10 - illustrates preferred 80MHz LTFs designed based on the second novel sequence in accordance with certain aspects of the present disclosure.
    [0027] Figures 11A-11B - illustrate example PAPR results for 80MHz LTFs designed based on a novel third sequence in accordance with certain aspects of the present disclosure.
    [0028] Figure 12 - illustrates preferred 80MHz LTFs designed based on the new third sequence in accordance with certain aspects of the present disclosure.
    [0029] Figure 13 - illustrates other exemplary operations for building a long training field sequence with very high transmission capacity (VHT-LTF) for 80 MHz channel in accordance with certain aspects of the present disclosure.
    [0030] Figure 13A - illustrates examples of components capable of performing the operations illustrated in Figure 13. Detailed Description of the Invention
    [0031] Various aspects of the disclosure are described in more detail below, with reference to the accompanying drawings. This disclosure may, however, be incorporated 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 for this disclosure to be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings of this document, one skilled in the art should understand that the scope of the disclosure is intended to cover any aspect of the disclosure disclosed in this document, whether implemented independently or in combination with any other aspect of the disclosure. For example, an apparatus can be implemented or a method can be practiced with any number of aspects set out herein. In addition, the scope of the disclosure is intended to cover such apparatus or method that is practiced using another structure, functionality or structure and functionality, in addition to or other than the various aspects of the disclosure set forth herein. It is to be understood that any aspect of the disclosure disclosed herein may be incorporated by one or more elements of a claim.
    [0032] The word "exemplary" is used here in the sense of "serving as an example, case or illustration". Any aspect described herein as "exemplary" is not necessarily to be interpreted as preferred or advantageous over other aspects.
    [0033] Although the particular aspects are described here, many variations and permutations of these aspects fall within the scope of the disclosure. Although some benefits and advantages of preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to certain 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 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 thereto. exemplary wireless communication system
    [0034] The techniques described here can be used for various wireless broadband communication systems, including communication systems that are based on an orthogonal multiplexing scheme. Examples of communication systems include Orthogonal Frequency Division Multiple Access (OFDMA) systems, Single Carrier Frequency Division Multiple Access (SC-FDMA) systems, and so on. An OFDMA system uses Orthogonal Frequency Division Multiplexing (OFDM), which is a modulation technique that divides the total system bandwidth into multiple orthogonal subcarriers. These subcarriers can also be called tones, beams, etc. With OFDM, each subcarrier can be independently modulated with data. An SC-FDMA system may use interleaved FDMA (IFDMA) to transmit on subcarriers that are distributed across the system bandwidth, localized FDMA (LFDMA) to transmit on a block of adjacent subcarriers, or enhanced FDMA (EFDMA) to transmit on several blocks of adjacent subcarriers. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA.
    [0035] The present teachings may be incorporated (eg implemented within or executed by) a variety of wired or wireless apparatus (eg nodes). In some aspects, a node implemented in accordance with the teachings of this document may include an access point or an access terminal.
    [0036] An access point ("AP") may comprise, be implemented as, or known as, Node B, Radio Network Controller ("RNC"), eNode B, Base Station Controller ("BSC"), Transceiver Station Base ("BTS"), Base Station ("BS"), Transceiver Function ("FT"), Radio Router, Radio Transceiver, Basic Service Set ("BSS"), Extended Service Set ("ESS"), Station Radio Base ("RBS"), or some other terminology.
    [0037] An access terminal ("AT") may comprise, be implemented as, or known as an access terminal, a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal, a user agent, a user device, user equipment, or some other terminology. In some implementations an access terminal may include a cellular telephone, a cordless telephone, a Session Initiation Protocol ("SIP") telephone, a wireless local loop station ("WLL"), a personal digital assistant ( "PDA"), a handheld device with wireless capability, or some other suitable processing device connected to a wireless modem. Thus, one or more aspects taught here can be incorporated into a telephone (eg a cell phone or smartphone), a computer (eg a laptop), a portable communication device, a portable computing device (eg. a personal data assistant), an entertainment device (eg a music or video device, or a satellite radio), a global positioning system device, a headset, a sensor or any other suitable device that is configured to communicate over a wireless or wired medium. In some respects the node is a wireless node. Such a wireless node can provide, for example, connectivity to or over a network (for example, a wide area network such as the Internet or a cellular network), through a wired or wireless communication link.
    [0038] Various aspects of a wireless network will now be presented with reference to Figure 1. Wireless network 100 is shown with several wireless nodes, commonly designated as nodes 110 and 120. Each wireless node is capable of receiving and/ or transmission. In the discussion that follows the term "receiving node" may be used to refer to a receiving node and the term "transmitting node" may be used to refer to a transmitting node. Such reference does not imply that the node is incapable of performing both transmit and receive operations.
    [0039] In the detailed description that follows, the term "access point" is used to designate a transmitting node and the term "access terminal" is used to designate a receiving node for downlink communications, while the term " access point" is used to designate a receiving node and the term "access terminal" is used to designate a transmitting node for uplink communications. However, those skilled in the art readily understand that other terminology or nomenclature may be used for an access point and/or access terminal. By way of example, an access point may be referred to as a base station, a base transceiver station, a station, a terminal, a node, an access terminal acting as an access point, or some other suitable terminology. An access terminal may be referred to as a user terminal, a mobile station, a subscriber station, a station, a wireless device, a terminal, a node or some other suitable terminology. The various concepts described throughout this disclosure are intended to apply to all appropriate wireless nodes, regardless of their specific nomenclature.
    [0040] Wireless network 100 can support any number of access points distributed throughout a geographic region to provide coverage for access terminals 120. A system controller 130 can be used to provide coordination and control of access points as well. as access to other networks (eg Internet) for the access terminals 120. For simplicity, an access point 110 is shown. An access point is generally a fixed terminal that provides backhaul services to access terminals in the geographic region of coverage, however, the access point may be mobile in some applications. An access terminal, which can be fixed or mobile, uses the return transport channel services of an access point or engages in point-to-point communications with other access terminals. Examples of access terminals include a telephone (eg, cell phone), a laptop computer, a desktop computer, a Personal Digital Assistant (PDA), a digital audio player (eg, MP3 player), a camera, a game console or any other suitable wireless node.
    [0041] One or more access terminals 120 may be equipped with multiple antennas to enable certain functionalities. With this configuration, multiple antennas at access point 110 can be used to communicate with a multiple antenna access terminal to improve data transmission capability without additional bandwidth or transmit power. This can be achieved by splitting a high data rate signal at the data transmitter into multiple lower rate data streams with different spatial signatures, allowing the receiver to separate those streams into multiple channels and properly combine the streams to retrieve the data signal from high rate.
    [0042] While portions of the following disclosure describe access terminals that also support multiple input and multiple output (MIMO) technology, the access point 110 may also be configured to support access terminals that do not support MIMO technology. This approach can allow older versions of access terminals (ie, "legacy" terminals) to remain deployed in a wireless network, extending its useful life, allowing new MIMO access terminals to be introduced as appropriate.
    [0043] In the detailed description that follows, various aspects of the invention will be described with reference to a MIMO system that supports any suitable wireless technology, such as Orthogonal Frequency Division Multiplexing (OFDM). OFDM is a technique that distributes data over a number of subcarriers spaced at precise frequencies. Spacing provides "orthogonality" that allows a receiver to retrieve data from subcarriers. An OFDM system can implement IEEE 802.11, 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 appropriate wireless technology, or any suitable combination of wireless technologies. A CDMA system can implement IS-2000, IS-95, IS-856, Wideband CDMA (WCDMA) or some other suitable air interface standard. A TDMA system may implement the 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 present invention are not limited to any particular wireless technology and/or air interface standard.
    [0044] Figure 2 illustrates a conceptual block diagram illustrating an example of the Physical Layer (PHY) signal processing functions. In a transmission mode, a TX 202 data processor can be used to receive data from the Media Access Control (MAC) layer and encode (code eg Turbo code) the data to facilitate early error correction ( FEC) at the receiving node. The encoding process results in a sequence of code code symbols that can be locked together and mapped to a signal constellation by the TX 202 data processor to produce a sequence of modulation symbols.
    [0045] In wireless nodes implementing OFDM, the modulation symbols coming from the TX data processor 202 can be provided to an OFDM modulator 204. The OFDM modulator divides the modulation symbols into parallel streams. Each stream is then mapped to an OFDM subcarrier and then combined using an Inverse Fast Fourier Transform (IFFT) to produce a time-domain OFDM stream.
    [0046] A TX 206 spatial processor performs the spatial processing on the OFDM stream. This can be done by spatially precoding each OFDM and then providing each spatially precoded stream to a different antenna 208 through a transceiver 206. Each transmitter 206 modulates an RF carrier with a respective precoded stream for transmission over the wireless channel.
    [0047] In a receive mode, each transceiver 206 receives a signal through its respective antenna 208. Each transceiver 206 can be used to retrieve the information modulated on an RF carrier and provide the information to an RX space processor 210.
    [0048] The RX 210 spatial processor performs spatial processing on the information to retrieve any spatial streams destined for the wireless node 200. The spatial processing can be performed in accordance with the Channel Correlation Matrix Inversion (CCMI), Minimum Square Error Medium (MMSE), Smooth Interference Cancellation (SIC) or some other suitable technique. If multiple spatial streams are destined for wireless node 200, they can be combined by spatial processor RX 210.
    [0049] In wireless nodes that implement OFDM, the stream (or combined stream) from the RX 210 spatial processor is provided to an OFDM 212 demodulator. The OFDM 212 demodulator converts the stream (or combined stream) from the time domain to the frequency domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate stream for each subcarrier of the OFDM signal. OFDM demodulator 212 retrieves the data (i.e., modulation symbols) carried on each subcarrier and multiplexes the data into a stream of modulation symbols.
    [0050] An RX data processor 214 can be used to translate the modulation symbols back to the correct point in the signal constellation. Because of noise and other wireless channel disturbances, modulation symbols cannot match an exact location of a point in the constellation of the original signal. The RX data processor 214 detects which modulation symbol was likely transmitted by finding the shortest distance between the received point and the location of a valid symbol in the signal constellation. These smooth decisions can be used, in the case of Turbo codes, for example, to calculate a log-likelihood ratio (LLR) of the code symbols associated with the data modulation symbols. The RX data processor 214 then uses the LLRs code symbol sequence to decode the data that was originally transmitted before providing the data to the MAC layer.
    [0051] Figure 3 illustrates a conceptual diagram illustrating an example of a hardware configuration for a processing system in a wireless node. In this example, processing system 300 can be implemented with a bus architecture generally represented by bus 302. Bus 302 can include any number of bus and interconnecting bridges depending on the specific application of processing system 300 and overall design constraints. The bus connects various circuits, including a 304 processor, machine readable media 306, and a 308 bus interface. The 308 bus interface can be used to connect a 310 network adapter, among other things, to the processing system 300, via of bus 302. The network adapter 310 can be used to implement the PHY layer signal processing functions. In the case of an access terminal 110 (see figure 1), a user interface 312 (eg keyboard, display, mouse, joystick, etc.) can also be connected to the bus. Bus 302 can also connect various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art and therefore will not be described further.
    [0052] The 304 processor is responsible for managing the bus and general processing, including the execution of software stored on machine-readable media 306. The 304 processor can be implemented with one or more general-purpose and/or special-purpose processors . Examples include microprocessors, microcontrollers, DSP processors, and other sets of circuits that can run software. Software shall be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Machine-readable media may include, by way of example, RAM (Random Access Memory), flash memory, ROM (Read Only Memory), PROM (Programmable Read Only Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), registers, magnetic disks, optical disks, hard disks, or any other suitable storage medium, or any combination thereof. Machine-readable media can be incorporated into a computer program product. The computer program product may include packaging materials.
    [0053] In the hardware implementation illustrated in Figure 3, machine readable media 306 is shown as part of processing system 300 separate from processor 304. However, as those skilled in the art will readily appreciate, machine readable media 306, or any portion thereof, may be external to processing system 300. By way of example, machine readable media 306 may include a transmission line, a data-modulated carrier wave, and/or a computer product separate from the node without wire, all of which can be accessed by the 304 processor through the 308 bus interface. Alternatively, or in addition, the machine readable media 306, or any part thereof, can be integrated into the 304 processor, as is the case with cache and/or general log files.
    [0054] Processing system 300 can be configured as a general purpose processing system with one or more microprocessors providing processor functionality and external memory providing at least a portion of machine readable media 306, all linked together with supporting a set of circuits through an external bus architecture. Alternatively, processing system 300 can be implemented with an ASIC (Application Specific Integrated Circuit) with processor 304, bus interface 308, user interface 312, in the case of an access terminal supporting the circuitry ( not shown), and at least a portion of machine readable media 306 integrated on a single chip, or with one or more FPGAs (Field Programmable Port Arrays), PLDs (Programmable Logic Device), controllers, state machines, logic closed, discrete hardware components, or any other suitable circuitry, or any combination of circuitry that can perform the various functionalities described throughout this disclosure. Those skilled in the art will recognize how best to implement the functionality described for processing system 300 depending on the specific application and global design constraints imposed on the global system.
    [0055] The wireless network 100 of figure 1 can represent the Wide Local Area Network (WLAN) IEEE 802.11, using the very high transmission capacity (VHT) protocol for signal transmission with a carrier frequency of 5 GHz ( ie, the IEEE 802.11ac specification) or with a carrier frequency of 60 GHz (ie, the IEEE 802.11n specification) targeting aggregate transmission capacities greater than 1 Gigabits per second. The 5GHz VHT specification can use a larger channel bandwidth, which can comprise two 40MHz channels to achieve 80MHz bandwidth, thus doubling the PHY data rate with insignificant increase in cost compared to the IEEE 802.11 standard n.
    Certain aspects of the present disclosure support construction of a training sequence within a preamble for VHT-based transmissions that can provide a lower peak/average power ratio (PAPR) than the training sequences used in the art. Building Long Boot Sequence for 80MHz Bandwidth
    [0057] A Very High Transmission Capacity Long Training Field (VHT-LTF) sequence of a transmit preamble can be used on one side of the receiver to estimate characteristics of a wireless channel. The 80MHz VHT-LTF sequence can be derived based on two approaches. In one aspect of the present disclosure, VHT-LTF can be derived using two 40MHz HT-LTFs to keep its PAPR low and autocorrelation properties high. To achieve this goal, the HT-LTF 40MHz can be doubled, frequency shifted, and then extra/missing subcarriers can be filled. This approach can be referred to as the "Legacy Approach" as existing 40MHz HT-LTF sequences can be used. In another aspect of the present disclosure, an entirely new LTF sequence can be constructed in order to obtain even better PAPR results. This approach can be referred to as the "New Sequence" approach.
    [0058] Figure 4 illustrates exemplary operations 400 for constructing the VHT-LTF sequence for 80MHz channel bandwidth in accordance with certain aspects of the present disclosure. At 402, the LTF sequence can be constructed by combining a plurality of interpolation sequences and one or more other sequences repeated several times with the appropriately chosen phase rotation (e.g., as defined in Figures 7-12 with different patterns of rotation [c1 c2 c3 c4]), in an effort to minimize (or at least reduce) the PAPR during transmission of the constructed LTF sequence. At 404, the constructed LTF sequence can be transmitted over a wireless channel, using, for example, a bandwidth of 80 MHz.
    [0059] Figure 13 illustrates exemplary operations 1300 for constructing the VHT-LTF sequence for 80MHz channel bandwidth, in accordance with certain aspects of the present disclosure. At 1302, the LTF sequence can be constructed by combining a plurality of interpolation sequences with LTF symbol values associated with at least one of the IEEE 802.11n standard or the IEEE 802.11a standard, wherein the LTF symbol values can cover at least a bandwidth portion of a first size, and each of the LTF symbol values may be repeated one or more times for different subcarriers. In 1304, the symbol phases of the LTF sequence can be rotated by bandwidth of the first size (for example, as defined in Figures 7-12 with different values of c1, c2, c3 and c4 of rotation patterns applied by sub- 20 MHz band) in an effort to minimize (or at least reduce) PAPR during an LTF stream transmission. At 1306, the LTF sequence can be transmitted over a wireless channel using a bandwidth of a second size. Building 80MHZ LTF sequence based on legacy approach
    [0060] In one aspect of the present disclosure, the 80MHz LTF sequence may be constructed using two 40MHz 802.11N LTFs as given by:

    [0061] It can be seen from equation (1) that there can be five subcarriers of zero in the entire tone of DC. vectors interp40Null, interp80ExtraL and interp80ExtraR can represent interpolation sequences used to fill in missing subcarrier values in LTFs to achieve a desired bandwidth, such as 80MHz bandwidth. Each interpolation sequence can comprise three subcarriers in this particular case, and can be optimized in an effort to minimize (or at least reduce) PAPR.
    [0062] Figure 5 illustrates PAPR results for 80MHz LTFs projected based on the approach given by equation (1), according to certain aspects of this disclosure. These cases in Figure 5 labeled "with rotation" refer to LTFs generated from equation (1) where the upper 40MHz frequency band can be rotated by 90 degrees. Approaches using 256-point Inverse Fourier Transform (IFFT) without oversampling prior to transmission (ie, baud rate of 80 mega samples per second) can provide lower bounds for cases of PAPRs for oversampling, and these PAPR results can match to preferred LTF sequences for cases with and without 90 degree phase rotation.
    [0063] In the case of oversampling with the 1024-point IFFT, the PAPR results for approaches with and without phase rotation can be very close, both greater than 7 dB, as illustrated in figure 5. These two approaches can have different preferred LTF sequences. In the case of IFFT 256 points and oversampling with 4 times time domain interpolation (4x TDI), the PAPR results can largely depend on filtering parameters. For example, the results listed in Figure 5 can be obtained with a filter cutoff frequency of 0.25, which may be the preferred frequency for this type of filtering. The LTF sequence generated with the 90 degree phase rotation of the upper 40MHz frequency band can provide the PAPR of 5.8816 dB, which is substantially less than the PAPR of 8.7891 dB obtained without the phase rotation.
    [0064] Subcarrier tones can be divided into more than two segments, and different phase rotation can be applied to each segment. This can result in even lower PAPR levels as the high PAPR can be mainly due to many independent subcarriers added together.
    [0065] If 40MHz upper band phase rotation is applied, as well as TDI-based oversampling, then the preferred 80MHz LTF sequence for the case defined by equation (1) is with PAPR of 5.8816 dB. This preferred LTF sequence can be given as:
    It can be seen by comparing equation (2) and equation (1) that the interpolation sequences can be given as:

    [0066] In another aspect of the present disclosure, the 80MHz LFT sequence may be constructed using two 40MHz 802.11n LFTs as given by:

    [0067] It can be seen from equation (4) that there can be three subcarriers of zero in the entire tone of DC. The interpolation sequences interp40Null, interp80ExtraL and interp80ExtraR can include extra tones to be chosen in an effort to minimize (or at least reduce) the PAPR.
    [0068] Figure 6 illustrates PAPR results for the 80 MHz LTFs projected based on the approach given by equation (4), according to certain aspects of the present disclosure. These cases in Figure 6 labeled "with rotation" refer to LTFs generated from equation (4) where the tone phases of the upper 40MHz frequency band can be rotated by 90 degrees.
    [0069] In the case of 256-point IFFT with oversampling based on 4 times time-domain interpolation (4x TDI), the PAPR results can again largely depend on filtering parameters. For example, the PAPR results of Figure 6 can be obtained with the filter cutoff frequency of 0.25. Phase rotation of tones from the frequency range greater than 90 degrees can provide a PAPR of 6.0423 dB, as illustrated in Figure 6, which is substantially less than the PAPR of 8.5841 dB obtained without phase rotation . This may represent the preferred result in the case of oversampling. It can be seen from Figures 56 that phase rotation in the upper band can substantially reduce the PAPR level.
    [0070] If 40MHz upper band phase rotation is applied, as well as TDI-based oversampling, then the preferred 80MHz LTF sequence for the case defined by equation (4) can provide a PAPR of 6.0423 dB (see figure 6). This preferred LTF sequence can be given as:
    It can be seen by comparing equations (4) and (5) that the interpolation sequences of equation (4) can be given as:
    Building 80MHZ LTF Sequence Based on New Sequencing Approach
    [0071] The 80MHz LTF sequence can be constructed using four 802.11a LTF sequences in the 20 MHz subbands covered by a complementary sequence, which can be equivalent to the phase rotation in each subband. Some additional tone values may also be determined in an effort to minimize (or at least reduce) PAPR during LTF sequence transmission.
    [0072] In one aspect of the present disclosure, the LTF sequence can be constructed as:

    [0073] It can be seen from equation (7) that there may be five subcarriers of zero in the entire DC tone, the interpolation sequences interp20Null, interp40Null, interp80ExtraL, interp80ExtraR can comprise extra tones to be chosen in an effort to minimize ( or at least reduce) to PAPR, and [c1 c2 c3 c4] may represent the complementary sequence.
    [0074] Figures 7A-7B illustrate an example of PAPR results for 80MHz LTFs designed based on the approach given by equation (7) with various phase rotation patterns in 20MHz subbands in accordance with certain aspects of the present disclosure . It can be seen from Figures 7A-7B that the new sequences built based on the four 20MHz 802.11a LTFs can provide, in general, improved PAPR results compared to the previously built sequences based on the two 40MHz 802.11n LTFs (ie the LTF sequences generated based on the legacy approach and given by equations (2) and (5)).
    [0075] It can also be seen from Figures 7A-7B that upper band phase rotation does not result in PAPR reduction, and PAPR results are even worse. Furthermore, the complementary sequences [1 1 -1 -1] and [1 -1 1 1] can provide better PAPR results than the sequences [1 1 -1 1] and [-1 1 1 1], while the complementary sequence [1 1 1 -1] can provide PAPR results very close to the standard [1 -1 1 1]. Using the complementary sequence [1 j 1 -j] combined with 90 degree phase rotation of the 40MHz upper band and oversampling based on time domain interpolation, new LTF sequences built on four 20MHz 802.11a LTFs can provide a PAPR of 5.8913 dB. It can be seen that this PAPR result is comparable with the PAPR result of 5.8816 dB (see Figure 5) of the LTF sequence defined by equation (2) which is constructed based on two 40MHz 802.11n LTFs.
    [0076] The preferred 80MHz LTF sequence built on the basis of four 20MHz 802.11a LTFs in a complementary sequence can be given as:
    where the interpolation sequences interp20Null, interp40Null, interp80ExtraL, interp80ExtraR and the rotation pattern [c1 c2 c3 c4] are shown in Figure 8 for various cases of no-oversampling and oversampling.
    [0077] In another aspect of the present disclosure, the 80MHz LTF sequence can be constructed using all 802.11a 20MHz and 802.11n 40MHz tones. Thus, in any 20MHz subband, each tone can be present in 802.11a 20MHz or in 802.11n 40MHz it can have the corresponding tone value of the 20MHz LTF sequence or the 40MHz HT-LTF sequence. In addition, complementary phase rotation sequence can be applied for 802.11a 20MHz bandwidth (ie, 802.11a tones can be rotated), and some missing tones can be filled.
    [0078] The constructed 80 MHz LTF sequence can be given as:

    [0079] It can be seen from equation (9) that there may be five subcarriers around the DC tone, interpolation sequences interp40Null, interp80ExtraL, interp80ExtraR may include extra tones to be chosen in an effort to minimize (or at least reduce) the PAPR and [c1 c2 c3 c4] can represent the complementary sequence. The advantage of this scheme is that there may not be a need to store different values for the existing 802.11 20MHz and 802.11n 40MHz tones. On the other hand, the PAPR level may be slightly higher because of fewer extra tones to choose from to reduce PAPR.
    [0080] Figures 9A-9B illustrate an example of PAPR results for 80 MHz LTFs designed based on the approach defined by equation (9), in accordance with certain aspects of the present disclosure. The newly generated LTF sequence given by equation (9) may represent a subset of the previously generated LTF sequence defined by equation (7). Therefore, the PAPR results achieved may not be better than those illustrated in Figures 7A-7B.
    [0081] The preferred 80MHz LTF sequence built on the basis of all 802.11a 20MHz and 802.11n 40MHz tones and the phase rotation of 802.11a 20MHz subbands can be given as:
    where the interpolation sequences interp40Null, interp80ExtraL, interp80ExtraR and the rotation pattern [c1 c2 c3 c4] from equation (10) are defined in Figure 10 for various cases of no-oversampling and oversampling.
    [0082] In yet another aspect of the present disclosure, the 80MHz LTF sequence can be constructed slightly by modifying the constructed LTF sequence defined by equation (9). All 802.11a 20MHz and 802.11n 40MHz tones can be used along with the complementary sequence phase rotation applied in each 20MHz bandwidth (ie, 802.11a 20MHz tones plus additional 802.11n 40MHz data tones). Also, some missing tones can be filled. Therefore, the constructed 80MHz LTF sequence can be given as:

    [0083] It can be seen from equation (11) that there may be five subcarriers around the DC tone, interpolation sequences interp40Null, interp80ExtraL, interp80ExtraR may include extra tones to be chosen in an effort to minimize (or at least reduce) the PAPR and [c1 c2 c3 c4] can represent the complementary sequence. The newly generated sequence defined by equation (11) may differ in rotational tone coverage from the LTF sequences defined by equations (7) and (9). The advantage of this particular system is that there may not be a need to store different values for the existing 802.11a 20MHz and 802.11n 40MHz tones. On the other hand, PAPR can be slightly worse because of fewer extra tones to be optimized in an effort to minimize (or at least reduce) PAPR.
    [0084] Figures 11A-11B illustrate an example of PAPR results for 80MHz LTFs designed based on the approach given by equation (11), in accordance with certain aspects of the present disclosure. The best PAPR result for the case of "no 80 Msps rotation" (ie 256 points IFFT) is 3.3233 dB, which is even better than the LTF sequence defined by equation (7) (ie, the PAPR of 3.4239 dB in Figure 8), due to different rotation tone coverage.
    [0085] The preferred 80MHz LTF sequence built on the basis of all 802.11a 20MHz and 802.11n 40MHz tones and 20MHz subband phase rotation can be given as:
    where the interpolation sequences interp40Null, interp80ExtraL, interp80ExtraR and the rotation pattern [c1 c2 c3 c4] from equation (12) are defined in figure 12 for various cases of no-oversampling and oversampling.
    [0086] The proposed approach to design LTF sequences can also be used for other subcarrier tone numbers. For example, in the case of the IEEE 802.11ac specification, some tones can be zeroed at band edges. Alternatively, all tones around the DC tone can be used.
    [0087] 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 components and/or module(s), including, but not limited to, a circuit, an application-specific integrated circuit (ASIC), or processor. Generally, when there are trades illustrated in the figures, these trades may have corresponding counterparty means-plus-function components with similar numbering. For example, blocks 402-404 and 1302-1306 shown in Figure 4 and Figure 13 correspond to circuit blocks 402A-404A and 1302A-1306A shown in Figure 4A and Figure 13A.
    [0088] As used here, the term "determination" encompasses a wide variety of actions. For example, "determination" may include calculation, computation, processing, derivation, investigation, searching (eg, searching a table, a database or other data structure), checking, and the like. In addition, "determination" may include receiving (eg receiving information), accessing (eg accessing data in a memory) and the like. Also, "determination" can include solving, selecting, choosing, creating, and so on.
    [0089] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items, including unique members. As an example, “at least one of: a, b or c” is intended to cover: a, b, c, ab, ac, bc and abc.
    [0090] The various operations of methods described above can be performed by any suitable means capable of performing the operations, such as various hardware and/or software components, circuits and/or modules. Generally, all operations illustrated in the figures can be carried out by corresponding functional means capable of carrying out the operations.
    [0091] The various illustrative logic blocks, modules and circuits described in connection with the present disclosure can be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA) signal or other programmable logic device (PLD) discrete gate or transistor logic, discrete hardware components, or a combination thereof designed to perform the functions described in this document. A general purpose processor can be a microprocessor, but alternatively, the processor can be any commercially available processor, controller, microcontroller or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors together with a DSP core, or any other such configuration.
    [0092] The steps of a method or algorithm described in connection with the present disclosure may be incorporated directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside on any type of storage medium that is known in the art. Some examples of storage media that can 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 on. A software module can include a single instruction, or many instructions, and can be distributed over several different code segments, among different programs, and on various storage media. Storage media can be coupled to a processor in such a way that the processor can read information from and write information to the storage medium. Alternatively, the storage medium may be an integral part of the processor.
    [0093] The methods disclosed in this document include one or more steps or actions to achieve the described method. Method steps and/or actions can be interchanged with each other 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 can be modified without departing from the scope of the claims.
    [0094] The described functions can be implemented in hardware, software, firmware or any combination of these. If implemented in software, functions can be stored as one or more instructions on a computer-readable medium. Storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to carry or store the desired program code in the form of instructions or data structures and which can be accessed by a computer. Disc and floppy disk, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray ® disc where floppy disk normally reproduces data magnetically, whereas discs reproduce data optically with lasers .
    [0095] Thus, some aspects may include a computer program product to perform the operations contained herein. For example, such a computer program product may include a computer-readable medium with instructions stored (and/or encoded) therein, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product can include packaging material.
    [0096] Software or instructions may also be transmitted via a transmission medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, micro -waves and then 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.
    [0097] In addition, it should be appreciated that modules and/or other suitable means to carry out the methods and techniques described in this document 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 media to perform the methods described in this document. Alternatively, various methods described in this document can be provided via storage media (eg, RAM, ROM, a physical storage medium such as a compact disk (CD) or floppy disk, etc.), such as a terminal The user and/or base station can obtain the various methods when docking or providing the storage medium for the device. In addition, any other technique suitable for providing the methods and techniques described herein for a device may be used.
    [0098] It should be understood that the claims are not limited to its specific configuration and components illustrated above. Various modifications, alterations 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.
    [0099] While the foregoing is directed to modalities of the present disclosure, and still other modalities of disclosure can be designed without departing from the basic scope thereof, and its scope is determined by the following claims.
    权利要求:
    Claims (17)
    [0001]
    1. Method for wireless communication, characterized in that it comprises: constructing a long training field (LTF) sequence, combining a plurality of interpolation sequences and one or more other sequences repeated several times in an effort to reduce a relationship peak/average power, PAPR, during a transmission of the constructed LTF sequence; and transmitting the constructed LTF sequence over a wireless channel using a bandwidth of a first size.
    [0002]
    2. Method according to claim 1, characterized by the fact that the construction of the LTF sequence comprises: designing the plurality of interpolation sequences in an effort to reduce PAPR.
    [0003]
    3. Method according to claim 2, characterized by the fact that the construction of the LTF sequence comprises: rotating phases of a plurality of symbols within one or more other sequences in an effort to reduce the PAPR.
    [0004]
    4. Method according to claim 3, characterized by the fact that one or more portions of one or more other sequences are designed in an effort to reduce PAPR.
    [0005]
    5. Method according to claim 3, characterized in that one or more portions of one or more sequences of the plurality of interpolation sequences are designed in an effort to reduce the PAPR.
    [0006]
    6. Method according to claim 1, characterized in that the construction of the LTF sequence comprises: rotating phases of a plurality of symbols of the LTF sequence constructed in an effort to reduce the PAPR, wherein the plurality of symbols belongs to a portion of the bandwidth.
    [0007]
    7. Method according to claim 6, characterized in that it further comprises: performing oversampling before transmission.
    [0008]
    8. Method according to claim 1, characterized in that the bandwidth of the first size comprises a bandwidth of 80 MHz.
    [0009]
    9. Apparatus for wireless communications, characterized in that it comprises: means for constructing a long training field (LTF) sequence, combining a plurality of interpolation sequences and one or more other sequences repeated several times in an effort to reduce a peak/average power ratio, PAPR, during a transmission of the constructed LTF sequence, and means for transmitting the constructed LTF sequence over a wireless channel using a bandwidth of a first size.
    [0010]
    10. Apparatus according to claim 9, characterized in that the means for constructing the LTF sequence comprises: means for designing the plurality of interpolation sequences in an effort to reduce PAPR.
    [0011]
    11. Apparatus according to claim 10, characterized in that the means for constructing the LTF sequence comprises: means for rotating phases of a plurality of symbols within the one or more other sequences in an effort to reduce the PAPR.
    [0012]
    12. Apparatus according to claim 11, characterized in that one or more portions of the one or more other sequences are designed in an effort to reduce PAPR.
    [0013]
    13. Apparatus according to claim 11, characterized in that one or more portions of one or more sequences of the plurality of interpolation sequences are designed in an effort to reduce the PAPR.
    [0014]
    14. Apparatus according to claim 9, characterized in that the means for constructing the LTF sequence comprises: means for rotating phases of a plurality of symbols of the LTF sequence constructed in an effort to reduce the PAPR, wherein the plurality of symbols belongs to a portion of the bandwidth.
    [0015]
    15. Apparatus according to claim 14, characterized in that it further comprises: means for performing oversampling before transmission.
    [0016]
    16. Apparatus according to claim 9, characterized in that the bandwidth of the first size comprises a bandwidth of 80 MHz.
    [0017]
    17. Computer-readable memory, characterized in that it contains recorded thereon the method as defined in any one of claims 1 to 8.
    类似技术:
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    BR112013002691B1|2021-12-14|VHT-SIG-B FIELD IN NULL DATA PACKAGES |
    BR112013004693B1|2021-12-28|GUARD INTERVAL SIGNALING FOR DETERMINING THE NUMBER OF DATA SYMBOLS
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    同族专利:
    公开号 | 公开日
    CA2768139C|2017-12-05|
    ZA201200829B|2012-10-31|
    HK1171295A1|2013-03-22|
    TWI450541B|2014-08-21|
    MX2012000561A|2012-02-21|
    JP2012533931A|2012-12-27|
    CN104735015B|2018-09-18|
    MY152713A|2014-11-28|
    WO2011008776A1|2011-01-20|
    US8917785B2|2014-12-23|
    KR101517038B1|2015-05-04|
    US20110013607A1|2011-01-20|
    JP5694316B2|2015-04-01|
    TW201130273A|2011-09-01|
    JP2015136120A|2015-07-27|
    EP2454862A1|2012-05-23|
    CN102474488B|2015-03-25|
    CA2768139A1|2011-01-20|
    CN104735015A|2015-06-24|
    EP2945336A1|2015-11-18|
    RU2012105463A|2013-08-27|
    KR20120049885A|2012-05-17|
    CN102474488A|2012-05-23|
    BR112012000857A2|2019-11-19|
    US20130242963A1|2013-09-19|
    RU2505935C2|2014-01-27|
    US8385443B2|2013-02-26|
    JP6363029B2|2018-07-25|
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    法律状态:
    2019-12-03| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2020-02-11| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-06-08| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
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    申请号 | 申请日 | 专利标题
    US22661509P| true| 2009-07-17|2009-07-17|
    US61/226,615|2009-07-17|
    US12/731,634|US8385443B2|2009-07-17|2010-03-25|Constructing very high throughput long training field sequences|
    US12/731,634|2010-03-25|
    PCT/US2010/041853|WO2011008776A1|2009-07-17|2010-07-13|Constructing very high throughput long training field sequences|
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