METHOD AND APPARATUS FOR CONSTRUCTION OF LONG TRAINING FIELD SEQUENCES AND VERY HIGH TRANSFER RATE

专利摘要:
method and apparatus for constructing sequences of long training field and very high throughput Certain aspects of the present description pertain to the techniques of constructing a sequence as a part of the transmission preamble in an effort to minimize (or at least reduce) a papr on a broadcast node.
公开号:BR112012025052B1
申请号:R112012025052-3
申请日:2011-04-06
公开日:2021-09-14
发明作者:Lin Yang；Didier Johannes Richard Van Nee；Hemanth Sampath
申请人:Qualcomm Incorporated；
IPC主号:

专利说明:

Priority Claim
The present patent application claims the benefits of Provisional Application No. 61/321,330, filed April 6, 2010, Provisional Application No. 61/321,752, filed April 7, 2010, Provisional Application No. 61/323,775 , filed April 13, 2010, from Provisional Application No. 61/332,360, filed May 7, 2010, from Provisional Application No. 61/333,168, filed May 10, 2010, from Provisional Application No. 61/ 334,260, filed May 13, 2010, provisional application No. 61/348,349, filed May 26, 2010, provisional application No. 61/350,216, filed June 1, 2010, and provisional application No. 61/354,898, filed on June 15, 2010, and assigned to the assignee hereof and expressly incorporated herein by reference. Field of Invention
Certain aspects of the present description relate generally to wireless communications, and more particularly to a method and apparatus for constructing a long sequencing field sequence (LTF) as a part of a transmission preamble for High Performance wireless systems. High (VHT). Fundamentals
The Institute of Electrical and Electronics Engineers (IEEE) 802.11 Wide Local Area Network (WLAN) standards embody established specifications for transmissions based on the VHT approach using a carrier frequency of 5 GHz (ie, IEEE 802.11ac specification) or using a carrier frequency of 60 GHz (that is, the IEEE 802.11ad specification), which aims to aggregate yields greater than 1 Gigabit per second. One of the technologies for the 5 GHZ VHT specification is a wider channel bandwidth, which joins two 40 MHZ channels to the 80 MHz bandwidth, thus doubling the physical layer (PHY) data rate with a negligible increase in cost compared to the IEEE 802.lln standard.
An LTF VHT is a part of a transmission preamble, and can be used on a receiver side to estimate the characteristics of the underlying MIMO wireless channel. Methods and apparatus are proposed in the present description to construct the LTF VHT sequence while providing a peak to low average power ratio (PAPR) at a transmitting node. summary
Certain aspects of this description support a method for wireless communications. The method generally includes constructing an LTF sequence from a preamble by combining a plurality of interpolation sequences with the LTF tone values associated with at least one IEEE 802.lln standard or the IEEE 802.11a standard, where the tone values LTF covers at least a portion of the bandwidth of a first size, and each of the LTF tone values is repeated one or more times for different subcarriers, rotating tone phase of the LTF sequence by bandwidth of the first size in an effort of reducing a PAPR during an LTF sequence transmission, and replacing the LTF sequence tones at the pilot sites with a defined sequence of chosen values in an effort to reduce the PAPR.
Certain aspects of the present description provide an apparatus for wireless communications. The apparatus generally includes a first circuit configured to build an LTF sequence from a preamble by combining a plurality of interpolation sequences with LTF tone values associated with at least one of the IEEE 802.11a standard and the IEEE 802.11a standard, where the LTF tone values cover at least a portion of the bandwidth of a first size, and each of the LTF tone values is repeated one or more times for different subcarriers, a second circuit configured to rotate the tone phases of the LTF sequence by bandwidth of the first size in an effort to reduce a PAPR during an LTF sequence transmission, and a third circuit configured to replace the LTF sequence tones at the pilot sites with a defined sequence of chosen values in an effort to reduce to PAPR.
Certain aspects of the present description provide an apparatus for wireless communications. The apparatus generally includes means for constructing an LTF sequence from a preamble by combining a plurality of interpolation sequences with LTF tone values associated with at least one of the IEEE 802.11a standard and an IEEE 802.11a standard, where the values of LTF tones cover at least a part of the bandwidth of a first size, and each of the LTF tone values is repeated one or more times for different subcarriers, means for rotating tone phases of the LTF sequence by bandwidth of the first size in an effort to reduce a PAPR during an LTF sequence transmission, and means to replace LTF sequence tones at pilot sites with a defined sequence of chosen values in an effort to reduce the PAPR.
Certain aspects of the present description provide a computer program product for wireless communications. The computer program product includes a computer-readable medium comprising executable instructions for constructing an LTF sequence from a preamble by combining a plurality of interpolation sequences with the LTF tone values associated with at least one of the IEEE 802.11 standard. the IEEE 802.11a standard, where LTF tone values cover at least a portion of the bandwidth of a first size, and each of the LTF tone values is repeated one or more times for different subcarriers, rotates the tone phases of the LTF sequence per bandwidth of the first size in an effort to reduce a PAPR during an LTF sequence transmission and replaces LTF sequence tones at pilot sites with a defined sequence of chosen values in an effort to reduce PAPR.
Certain aspects of this description provide an access point. The access point generally includes an antenna, a first circuit configured to build an LTF sequence from a preamble by combining a plurality of interpolation sequences with the LTF tone values associated with at least one of the IEEE 802.11 standard. IEEE 802.11a standard, where the LTF tone values cover at least a portion of the bandwidth of a first size, and each of the LTF tone values is repeated one or more times for different subcarriers, a second circuit configured to rotate phases of LTF sequence tones per bandwidth of the first size in an effort to reduce a PAPR during an LTF sequence transmission, a third circuit configured to replace LTF sequence tones at pilot sites with a defined sequence of values chosen in an effort to reduce the PAPR, and a transmitter configured to transmit through at least one antenna the LTF sequence using a bandwidth of one sec. undo size. Brief Description of Drawings
So that the way in which the above-mentioned features of the present description may be understood in detail, a more particular description, briefly summarized above, can be had with reference to aspects, some of which are illustrated in the accompanying drawings. It should be noted, however, that the attached drawings illustrate only certain typical aspects of this description and, therefore, should not be considered as limiting its scope, as the description may admit other aspects that are equally effective.
Figure 1 illustrates a diagram of a wireless communications network in accordance with certain aspects of the present description;
Figure 2 illustrates an illustrative block diagram of the signal processing functions of a PHY of a wireless node in the wireless communications network of Figure 1 in accordance with certain aspects of the present description;
Figure 3 illustrates a block diagram of an illustrative hardware configuration for a processing system at a wireless node in the wireless communications network of Figure 1 in accordance with certain aspects of the present description;
Figure 4 illustrates an illustrative preamble structure comprising an LTF VHT sequence in accordance with certain aspects of the present disclosure;
Figures 5a to 5j illustrate exemplary transmission PAPR results for preferred LTF VHT sequences constructed for the 80 MHz channel in accordance with certain aspects of the present description;
Figure β illustrates an illustrative LTF VHT sequence constructed in an effort to reduce PAPR in accordance with certain aspects of the present description;
Figure 7a illustrates illustrative values in pilot tones of LTF VHT sequence chosen in an effort to reduce PAPR in accordance with certain aspects of the present description;
Figures 7b to 7i illustrate examples of PAPR results for different LTF VHT sequences constructed for transmission over an 80 MHz channel in accordance with certain aspects of the present description;
Figures 8a to 8c illustrate examples of LTF VHT sequences constructed for transmission over the 80 MHz channel in accordance with certain aspects of the present description;
Figure 9 illustrates illustrative operations that can be performed on a wireless node to build an LTF VHT sequence for transmission over the 80 MHz channel in accordance with certain aspects of the present description;
Figure 9a illustrates illustrative components capable of performing the operations illustrated in Figure 9;
Figures 10a and 10b illustrate illustrative minimum PAPR results for different phase rotation patterns applied to the construction of Legacy Long Sequencing Field (L-LTF) and Legacy Short Sequencing Field (L-STF) of a VHT transmission preamble in accordance with certain aspects of the present description. Detailed Description
Various aspects of the description are described more fully hereinafter with reference to the accompanying drawings. This description can, however, be embodied in many different forms and should not be construed as limited to any specific structure or function presented through that description. Rather, these aspects are provided so that this description is complete, and fully carries the scope of the description to those skilled in the art. Based on the teachings presented herein, those skilled in the art should appreciate that the scope of the description should cover any aspect of the description described herein, implemented independently or in combination with any other aspect of the description. For example, an apparatus can be implemented or a method can be practiced using any number of aspects presented here. Additionally, the scope of the description shall cover such apparatus or method that is practiced using another structure, functionality, or structure and functionality in addition to or in addition to various aspects of the description presented here. It is to be understood that any aspect of the description described herein may be substantiated by one or more elements of a claim.
The term "illustrative" is used herein to mean "serving as an example, case or illustration". Any aspect described herein as "illustrative" is not necessarily to be regarded as preferred or advantageous over other aspects.
Although particular features are described here, many variations and permutations of these features are within the scope of the description. Although some benefits and advantages of preferred aspects are mentioned, the scope of description should not be limited to particular benefits, uses or objectives. Rather, aspects of the description should 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 description rather than limiting, the scope of the description being defined by the appended claims and their equivalents.
An example of wireless communication system
The techniques described here can be used for various broadband wireless communication systems, including communication systems that are based on an orthogonal multiplexing scheme. Examples of such 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 bandwidth of the system as a whole into multiple orthogonal subcarriers. These subcarriers can also be called tones, compartments, 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 multiple blocks of adjacent subcarriers. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDMA.
The teachings presented herein can be incorporated (eg, implemented within or performed by) a variety of wired and wireless devices (eg, nodes). In some aspects, a node implemented in accordance with the teachings presented here may comprise an access point or an access terminal.
An access point (AP) may comprise, be implemented as, or known as, Node B, Radio Network Controller (RNC), eNodeB, Base Station Controller (BSC), Radio Transceiver Station (BTS), Base Station ( BS) , Transceiver Function (TF), Radio Router, Radio Transceiver, Basic Service Set (BSS), Extended Service Set (ESS), Radio Base Station (RBS), or some other terminology.
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, a user equipment, or some other terminology. In some implementations an access terminal may comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) telephone, a wireless local circuit station (WLL), a personal digital assistant (PDA), a handheld device having wireless capability, or some other suitable processing device connected to a wireless modem. Accordingly, one or more of the aspects taught here may be incorporated into a telephone (eg, a cell phone or smart phone), a computer (laptop), a portable communication device, a portable computing device (eg, a personal data assistant), an entertainment device (for example, 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 to a network (for example, a wide area network such as the Internet or a cellular network) through a wired or wireless communication link.
Various aspects of a wireless network will now be presented with reference to Figure 1. Wireless network 100 is illustrated with several wireless nodes, commonly referred to as nodes 110 and 120. Each wireless node is capable of receiving and/or transmitting. In the discussion that follows the term "receiving node" can be used to refer to a node that is receiving and the term "transmitting node" can be used to refer to a node that is transmitting. Such reference does not imply that the node is incapable of performing operations and transmission and reception.
In one aspect of the present description, wireless network 100 may represent IEEE 802.11 WLAN using the VHT protocol to signal transmissions using a carrier frequency of 5 GHz (i.e., IEEE 802.11ac specification) or using a carrier frequency of 60 GHz ( that is, IEEE 802.11ad specification) which aims to aggregate yields greater than 1 gigabits per second. The 5GHz VHT specification can use a wider channel bandwidth, which can comprise two 40MHz channels to achieve 80MHz bandwidth, thus doubling the PHY data rate with a negligible increase in cost compared to the IEEE 802.lln standard.
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 "point "access terminal" 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 will 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 description should apply to all suitable wireless nodes regardless of their specific naming.
Wireless network 100 can support any number of access points distributed throughout a geographic region to provide coverage for access terminals 102. A system controller 130 can be used to provide coordination and control of access points in addition to access to other networks (eg the Internet) to access terminals 120. For the sake of simplicity, an access point 110 is illustrated. An access point is generally a fixed terminal that provides return access channel services to access terminals in the geographic region of coverage; however, the hotspot may be mobile in some applications. In one aspect of the present description, at the access point 110, an LTF VHT sequence may be constructed within a VHT preamble transmitted to one or more of the access terminals 120 in order to achieve a preferred level of PAPR at a transmitter of the access point. access 110. An access terminal, which may be fixed or mobile, utilizes the return access channel services of an access point or engages in peer-to-peer communications with other access terminals. Examples of access terminals include a telephone (eg a cell phone), a laptop computer, a desktop computer, a PDA, a digital audio device (eg an MP3 player), a camera, a game console, or any other suitable wireless node.
One or more access terminals 102 may be equipped with multiple antennas to allow for certain functionality. With that configuration, multiple antennas at access point 110 can be used to communicate with the multiple antenna access terminal to improve data throughput without additional bandwidth or transmission power. This can be achieved by dividing a high data rate signal at the transmitter into multiple lower rate data sequences with different spatial signatures, thus allowing the receiver to separate these sequences into multiple channels and properly combine the sequences to retrieve the high rate data signal.
While parts of the description below will describe access terminals that also support MIMO technology, access point 110 can also be configured to support access terminals that do not support MIMO technology. This approach can allow older versions of access endpoints (ie, "legacy" endpoints) to remain deployed over a wireless network, extending its lifetime, while allowing newer MIMO access endpoints to be introduced as appropriate.
In the detailed description that follows, various aspects of the invention will be described with reference to a system
MIMO supporting any suitable wireless technology such as OFDM. OFDM is a technique that distributes data across multiple 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, CDMA, TDMA, or any other suitable wireless technology, or any combination of suitable wireless technologies. A CDMA system can implement with IS-2000, IS-95, IS-856, WCDMA, or some other suitable air interface standard. A TDMA system can implement GSM or some other suitable area interface standard. As those skilled in the art will readily appreciate, the various aspects of this invention are not limited to any particular wireless technology and/or air interface standard.
Figure 2 illustrates a conceptual block diagram illustrating an example of the PHY layer 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 (eg Turbo code) the data to facilitate forward error correction (FEC) ) at the receiving node. The encoding process results in a sequence of code symbols that can be locked together and mapped into a signal constellation by the TX 202 data processor to produce a sequence of modulation symbols. In one aspect of the present description, the TX data processor 202 can generate an LTF VHT sequence within a transmit VHT preamble in order to achieve the preferred level of PAPR.
In wireless nodes implementing OFDM, the TX data processor 202 modulation symbols can be provided to an OFDM 204 modulator. The OFDM modulator divides the modulation symbols into parallel sequences. Each sequence is then mapped onto an OFDM subcarrier and then combined using an Inverted Fast Fourier Transform (IFFT) to produce a time-domain OFDM sequence.
A spatial processor TX 206 performs spatial processing on the OFDM sequence. This can be accomplished by spatially precoding each OFDM and then delivering each spatially precoded sequence to a different antenna 208 through a transceiver 206. Each transmitter 206 modulates an RF carrier with a respective precoded sequence to transmission over the wireless channel.
In a receive mode, each transceiver 206 receives a signal through its respective antenna 208. Each transceiver 206 can be used to retrieve modulated information on an RF carrier and provide the information to an RX spatial processor 210.
RX spatial processor 210 performs spatial processing on the information to retrieve any spatial sequences destined for wireless node 200. Spatial processing may be performed in accordance with Channel Correlation Matrix Inversion (CCMI), Minimum Mean Square Error ( MMSE), Smooth Interference Cancellation (SIC) or some other suitable technique. If multiple spatial sequences are intended for wireless node 200, they can be combined by the spatial processor of RX 210.
In wireless nodes implementing OFDM, the sequence (or combined sequence) of the RX spatial processor 210 is provided to an OFDM demodulator 212. The OFDM demodulator 212 converts the sequence (or combined sequence) from time domain to frequency domain using an FFT . The frequency domain signal comprises a separate sequence for each subcarrier of the OFDM signal. OFDM demodulator 212 retrieves the data (ie, modulation symbols) carried on each subcarrier and multiplexes the data into a sequence of modulation symbols.
An RX data process 214 can be used to translate the modulation symbols back to the correct point in the signal constellation. Due to noise and other disturbances on the wireless channel, modulation symbols may not match an exact location of a point in the original signal constellation. The RX data processor 214 detects which modulation symbol has not been transmitted by finding the shortest distance between the received point and the location of a valid symbol in the signal constellation. These soft decisions can be used, in the case of Turbo codes, for example, to compute an Archival Probability Ratio (LLR) of the code symbols associated with the given modulation symbols. The RX data processor 214 then uses the sequence of code symbol LLRs in order to decode the data that was originally transmitted prior to providing the data to the MAC layer.
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 interconnecting buses and bridges depending on the specific application of processing system 300 and design constraints as a whole. The bus links several circuits including a processor 304, machine readable media 306, and a bus interface 308. The bus interface 308 can be used to connect a network adapter 310, among other things, to the processing system 300 over the 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 . 312 user interface (eg keyboard, monitor, 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.
Processor 304 is responsible for bus management and general processing, including executing software stored on machine readable medium 306. Processor 304 may be implemented with one or more general purpose and/or special purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuit sets that can run software. Software shall be taken broadly to mean instructions, data, or any combination thereof, 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 embodied in a computer program product. The computer program product may comprise packaging materials. In one aspect of the present description, processor 304 may perform or direct operations 900 of Fig. 9 and/or other processes for the techniques described herein.
In the hardware implementation illustrated in Figure 3, machine readable media 306 is illustrated 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 part thereof. 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 wireless node, all of which can be accessed by the 304 processor via the 308 bus interface. Alternatively, or additionally, the 306 machine readable media, or any part thereof, may be integrated with the 304 processor, as may be the case with temporary storage and/or general log files.
Processing system 300 may 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 the machine readable media 306, all connected with another support circuitry through of an external bus architecture. Alternatively, processing system 300 can be
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 embodied in a computer program product. The computer program product may comprise packaging materials. In one aspect of the present description, processor 304 may perform or direct operations 900 of Fig. 9 and/or other processes for the techniques described herein.
In the hardware implementation illustrated in Figure 3, machine readable media 306 is illustrated 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 part thereof. 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 wireless node, all of which can be accessed by the 304 processor through the 308 bus interface. Alternatively, or additionally, the 306 machine readable media, or any part thereof, may be integrated with the 304 processor, such. as may be the case with temporary storage and/or general log files.
Processing system 300 may 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 the machine readable media 306, all connected with another support circuitry through of an external bus architecture. Alternatively, the processing system 300 can be implemented with an ASIC (Application Specific Integrated Circuit) with the processor 304, the bus interface 308, the user interface 312 in the case of an access terminal, supporting the circuitry ( not shown), and at least a portion of the machine readable media 306 integrated to a single chip or to one or more FPGAs (Field Programmable Gate Sets), PLDs (Programmable Logic Devices), controllers, state machines, logic with port, discrete hardware components, or any other suitable circuit set, or any combination of circuits that can perform the various functionality described throughout this description. Those skilled in the art will recognize how best to implement the functionality described for processing system 300 depending on the particular application and general design constraints imposed on the system as a whole.
Certain aspects of the present description support a method and apparatus for constructing a sequence as part of the VHT transmission preamble so that a PAPR at a transmission node can be sufficiently low. In one aspect, the sequencing sequence can comprise an LTF VHT sequence.
Long Sequencing Field Sequence Construction Methods for 80 MHz Channel Bandwidth Figure 4 illustrates an illustrative structure of a preamble 400 comprising an LTF VHT sequence in accordance with certain aspects of the present description. Preamble 400 may be transmitted from access point 110 to one or more access terminals 120 in wireless network 100 illustrated in Fig. 1. Preamble 400 may be transmitted in accordance with the IEEE 802.11ac specification or in accordance with the IEEE specification 802.Had.
In one aspect of the present description, preamble 400 may comprise an omnileg portion 402 and a pre-encoded VHT 802.11ac portion 414. Legacy portion 402 may comprise: L-STF 404, a legacy long sequencing field 406, one legacy signal field (L-SIG) 408, and two OFDM symbols 410, 412 for each type A very high throughput signal field (VHT-SIG-A fields). VHT-SIG-A 410, 412 fields can be transmitted omnidirectional. The pre-encoded VHT 802.11ac portion 414 may comprise: a very high throughput short sequencing field (VHT-STF) 416, a very high throughput long sequencing field 1 (VHT-LTF1) 418, long sequencing fields of very high throughput (VHT-LTFs) 420, a type B very high throughput signal field (VHT-SIG-B field 422) and a data packet 424. The VHT-SIG-B field can comprise an OFDM symbol and can be transmitted in pre-encoded or bundled form.
Robust multi-user MIMO (MU) reception may require the AP to broadcast all 420 VHT-LTFs to all supported users. The VHT-LTF 420 sequence can allow each user to estimate a MIMO channel from all AP antennas to user antennas. User can use estimated channel to perform effective interference cancellation of MU-MIMO sequences corresponding to other users. In one aspect of the present description, a novel structure of the VHT-LTF 420 sequence can be constructed in an effort to minimize (or at least reduce) PAPR in an AP transmitter.
In one aspect of the present description, the VHT-LTF sequence can be constructed for the 80 MHz channel by using four 802.11a LTF sequences in 20 MHz subbands covered by a complementary sequence, where the complementary sequence can be equivalent to phase rotation in each of the 20 MHz subbands. In addition, some additional pitch values can be chosen in an effort to minimize (or at least reduce) the PAPR during the transmission of the VHT-LTF sequence. Thus, the VHT-LTF standard can be defined as:

It can be seen from equation (1) that there can be a maximum of three zero tone values (subcarriers) around the DC tone, the interpolation sequences interp20Null, interp4ONull, interp80ExtraL, interpθOExtraR may comprise additional tones to be chosen in an effort to minimize (or at least reduce) PAPR, and [cl c2 c3 c4] may represent the complementary sequence.
By applying various phase rotation patterns to the 20 MHz subbands, different PAPR results can be obtained when transmitting VHT-LTF sequences designed based on the VHT-LTF pattern from equation (1). In general, VHT-LTF sequences built on four 20 MHz 802.11a LTF sequences can provide improved PAPR results compared to VHT-LTF sequences built on two 802.lln LTF sequences on 40 MHz subbands .
It should be noted that phase rotation of the upper 40 MHz band may not result in PAPR reduction; PAPR results can be even worse. In one aspect, the complementary sequences [111 -1] and [1-11 1] may provide better PAPR results than the complementary sequences [1 1 -1 1] and [-1 111]. Also, 90 degree phase rotation of an odd or even 20 MHz subband may not help further reduce PAPR.
VHT-LTF sequences built for 80 MHz channel bandwidth based on the pattern of equation (1) can provide preferred PAPR results for different cases of oversampling and oversampling, if VHT-LTFs comprise interp20Null interpolation sequences , interp4ONull, interp80ExtraL, interp80ExtraR and the rotation pattern [cl c2 c3 c4] according to figure 5. It should be noted that the label "with rotation" in figure 5a and in figures 5b to 5j that follow refers to rotation phase shift of tones in the upper 40 MHz band by 90 degrees, while the label "4x TDI" refers to 4-time oversampling based on time domain interpolation (TDI) . Sampling rates of 80 mega samples per second (Msps) or 320 Msps can be used, as illustrated in figures 5a through 5j.
In one aspect of the present description, the VHT-LTF stream can be constructed for transmission over the 80 MHz channel by using all 802.11a tones of 20 MHz and 802.11a tones of 40 MHz. 20 MHz band, each tone that can be present in 20 MHz 802.11a or 40 MHz 802.lln can have the corresponding tone value of the 20 MHz LTF sequence or the 40 MHz HT-LTF sequence. complementary phase rotation sequence can be applied by 802.11a bandwidth of 20 MHz (that is, 802.11a tones can be rotated), and a few missing tones can be filled. In this case, the VHT-LTF standard can be provided as:

It can be seen from equation (2) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp4ONull, interpδOExtraL, interpδOExtraR can comprise additional tones to be chosen in an effort to minimize (or at least reduce ) to PAPR, and [cl c2 c3 c4 ] can represent the complementary phase rotation sequence. An advantage of the VHT-LTF standard in equation (2) may be that there may not be a need to store different values for the existing 20 MHz 802.11a and 802. lln 40 MHz tones. On the other hand, a PAPR level may be slightly higher than the standard VHT-LTF of equation (1) due to fewer additional tones being chosen in an effort to minimize (or at least reduce) the PAPR.
By applying various phase rotation patterns in 20 MHz subbands, different PAPR results can be obtained when transmitting 80 MHz VHT-LTF sequences designed based on the VHT-LTF pattern from equation (2) . It can be seen that the VHT-LTF sequences based on the pattern in equation (2) may represent a subset of the previously generated VHT-LTF sequences based on the pattern in equation (1). Therefore, the PAPR results of the VHT-LTF sequences constructed based on the pattern in equation (2) may not be better than the PAPR results of the VHT-LTF sequences constructed based on the pattern in equation (1) . VHT-LTF sequences built for the 80 MHz channel bandwidth based on the pattern of equation (2) can provide the preferred PAPR results for different cases of oversampling and oversampling, if VHT-LTFs comprise the sequences of interpolation interpiONull, interp80ExtraL, interp80ExtraR and the rotation pattern [cl c2 c3 c4] according to figure 5b.
In one aspect of the present description, the VHT-LTF sequence can be constructed for transmission over the 80 MHz channel by slightly modifying the VHT-LTF pattern defined by equation (2). All 20MHz 802.11a tones and 40MHz 802.lln tones can be used along with the complementary phase rotation sequence applied to each 20MHz subband (ie, 20MHz 802.11a tones plus 20MHz tones additional data from 802.lln at 40 MHz). Additionally, a few missing tones can be filled. In this case, the VHT-LTF standard for the 80 MHz channel can be given as: Eq.3:


It can be seen from equation (3) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp4ONull, interpδOExtraL, interpδOExtraR can comprise additional tones to be chosen in an effort to minimize (or at least reduce ) to PAPR, and [cl c2 c3 c4] can represent the complementary phase rotation sequence. VHT-LTF sequences based on the pattern of equation (3) may differ in rotational pitch coverage from VHT-LTF sequences based on equations (1) and (2) . An advantage of the VHT-LTF standard defined by equation (3) may be that there may not be a need to store different values for the existing 602.11a 20 MHz and 602. lln 40 MHz tones. On the other hand, a PAPR level may be slightly higher compared to the VHT-LTF standard defined by equation (1) due to fewer additional tones to be optimized in an effort to minimize (or at least reduce) the PAPER
VHT-LTF sequences built for 60 MHz channel bandwidth based on the pattern of equation (3) can provide preferred PAPR results for different cases of non-oversampling and oversampling, if VHT-LTFs comprise interpolation sequences interp40Null, interpδOExtraL, interpδOExtraR, and the rotation pattern [cl c2 c3 c4] according to figure 5c. It can be seen from Figure 5c that the best PAPR result of 3.2110 dB can be obtained, which is better than that of the VHT-LTF sequence based on the pattern of equation (1) (eg PAPR of 3, 2163 dB according to figure 5a) due to different rotation tone coverage.
In one aspect of the present description, the VHT-LTF sequence can be constructed for transmission over the 80 MHz channel by using existing 20 MHz 802.11a and 802.11a tones, 40 MHz lln with complementary sequence phase rotation applied in each 20 MHz subband (that is, 20 MHz 802.11a tones plus additional 40 MHz 802.lln data tones) and fill in the few missing tones. In this case, the VHT-LTF pattern can be given as: Eq.4:

It can be seen from equation (4) that there may be three subcarriers equal to zero around the DC tone, interpolation sequences interp4ONull, interpδOExtraL, interpδOExtraR, can comprise additional tones to be chosen in an effort to minimize (or by the minus reduce) to PAPR, and [cl c2 c3 c4] may represent the complementary sequence. The VHT-LTF pattern defined by equation (4) may differ from the VHT-LTF pattern defined by equation (3) in that four additional tones in addition to interpδOExtraL and interp80ExtraR can be filled by LTF 802.lln values of 20 MHz. The VHT sequences -LTFs built for the 80 MHz channel bandwidth based on the pattern defined by equation (4) can provide preferred PAPR results for various cases of non-oversampling and oversampling, if the built VHT-LTFs understand the interpolation sequences interp4ONull, interp80ExtraL, interp8OExtraR, and the rotation pattern [cl c2 c3 c4] according to figure 5d. In one aspect of the present description by modifying the VHT-LTF standard defined by equation (4), the VHT-LTF stream can be constructed for transmission over the 80 MHz channel by using all 802.11a tones of 20 MHz, 802. lln at 20 MHz and 802.lln at 40 MHz, and by using identical interpolation sequences interpδOExtraL, interp80ExtraR. In this case, the VHT-LTF standard can be provided as:

It can be seen from equation (5) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp4ONull, interp80Extra can comprise additional tones to be chosen in an effort to minimize (or at least reduce) a PAPR, and [cl c2 c3 c4] may represent the complementary sequence. VHT-LTF sequences built for the 80 MHz channel bandwidth based on the pattern defined by equation (5) can provide preferred PAPR results for different cases of non-oversampling and oversampling, if the VHT-LTF sequences comprise the interpolation sequences interp4ONull, interpδOExtra and the rotation pattern [cl c2 c3 c4] according to figure 5e.
In one aspect of the present description, for 242 subcarriers allocated for the VHT-LTF pattern, the VHT-LTF pattern starting at subcarrier number -128 of the 80 MHz band may comprise a 600 bit sequence illustrated in Figure 6. The VHT- pattern LTF 600 can use at least one of the existing 40MHz 802.lln subcarrier values or 20MHz 802.lln subcarrier values (around DC only). This VHT-LTF sequence may require ten additional subcarriers, four around DC and six around 40 MHz DC 802.lln subcarriers. The interpolation sequences can be given as [ Interp40Null interpδOExtraL interpδOExtraR interp4ONullR] = {1, -1 , -1, -1, -1, 1, -1, 1, 1, -1}, where the first three values can match Interp40Null, the next two values can match InterpδOExtraL, the next two values can match InterpδOExtraR , and the last three values can correspond to Interp4ONullR.
One difference between the VHT-LTF 600 sequence and the VHT-LTF patterns defined by equations (1) - (5), is that three Interp40Null tones can be different for the left and right part of the VHT-LTF 600 sequence (ie, for the upper and lower 40 MHz band) . In one aspect, an additional phase rotation per subband of 20 MHz can be applied on top of the 600 binary values, where the phase rotation can correspond to any multiples of 90 degrees.
In one aspect of the present description, the {1, 1, 1, -1} phase rotation pattern applied per 20 MHz subband can provide a preferred PAPR of 4.76 dB using cyclic interpolation and oversampling of 4 times. In that case, the signals of at least 64 elements of the 600 sequence can be inverted. In another aspect, in order to preserve the 90 degree phase shift between the upper and lower 40 MHz subchannel, a rotation pattern of {1, j, 1, j} can be used with the ten additional subcarrier values preferred being {1, -1, 1, -1, -1, 1, -1, -1, -1, -1}.
In one aspect of the present description, different null pitch values can be used for different parts of the 80 MHz bandwidth (that is, for the upper and lower 40 MHz subchannels) in the VHT-LTF pattern defined by equation (3) . In this case, the VHT-LTF standard for transmission over the 80 MHz channel can be provided as: Eq.6:

It can be seen from equation (6) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp40Null, interp40NullR, interpδOExtraL, interpδOExtraR may comprise additional tones to be chosen in an effort to minimize (or at least reduce) the PAPR, and [cl c2 c3 c4] may represent the complementary sequence. VHT-LTF sequences built for 80 MHz channel bandwidth based on the pattern of equation (6) can provide preferred PAPR results for different cases of non-oversampling and oversampling, if the VHT-LTF sequences comprise the sequences of interpolation interp4ONull, interp4ONullR, interpδOExtraL, interpδOExtraR, and the phase rotation pattern [cl c2 c3 c4] according to figure 5b.
In one aspect of the present description, different null tone values for the upper and lower 40 MHz subchannels can be used in the VHT-LTF pattern defined by equation (3) . In this case, the VHT-LTF sequence for transmission over the 80 MHz channel can be provided as: Eq.7:

It can be seen from equation (7) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp4ONull, interp40NullR, interpδOExtraL, interpδOExtraR may comprise additional tones to be chosen in an effort to minimize (or at least reduce) the PAPR, and [cl c2 c3 c4] may represent the complementary sequence. The VHT-LTF pattern of equation (7) can be defined in the same way as the VHT-LTF pattern of equation (6), but a different method to generate oversampled sequences with IFFT size 1024 can be used. VHT-LTF sequences built for 80 MHz channel bandwidth based on the pattern of equation (7) can provide preferred PAPR results for different cases of non-oversampling and oversampling, if the VHT-LTF sequences comprise the sequences interp4ONull, interp4ONullR, interp80ExtraL, interp80ExtraR and the phase rotation pattern [cl c2 c3 c4] according to figure 5g.
In one aspect of the present description, by modifying the. VHT-LTF standard defined by equation (2), the VHT-LTF sequence can also be constructed for the 80 MHz channel by using all 802.11a tones of 20 MHz and 802 tones of 40 MHz with phase rotation of complementary sequence applied to each 20 MHz subband (802.11a of 20 MHz plus additional data tones of 802.lln of 40 MHz) and filling in the few tones that are missing. In this case, the VHT-LTF standard for transmission over the 80 MHz channel can be set as: Eq.8:

It can be seen from equation (4) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp4ONull, interpδOExtraL, interpδOExtraR, which can comprise additional tones to be chosen in an effort to avoid (or by) minus reduce) to PAPR, and [cl c2 c3 c4] may represent the complementary sequence. The VHT-LTF pattern of equation (8) can be defined in the same way as the VHT-LTF pattern of equation (3), but a different method to generate oversampling sequences with IFFT size 1024 can be used. VHT-LFT sequences built from 80 MHz channel bandwidth based on the pattern of equation (8) can provide preferred PAPR results for different cases of non-oversampling and oversampling, if the VHT-LTF sequences comprise sequences of interpolation interpíONull, interpδOExtraL, interpδOExtraR and the phase rotation pattern [cl c2 c3 c4] according to figure 5h.
In one aspect of the present description, by modifying the VHT-LTF pattern defined by equation (8), the VHT-LTF sequence for transmission over the 80 MHz channel can also be constructed by using all 802 tones. lln of 40 MHz with complementary sequence phase rotation applied to each 20 MHz subband and filling in a few tones missing. In this case, the VHT-LTF standard for transmission over the 80 MHz channel can be provided as: Eq.9:


It can be seen from equation (9) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp4ONull, interpδOExtraL, interpδOExtraR can comprise additional tones to be chosen in an effort to minimize (or at least reduce) to PAPR, and [cl c2 c3 c4 ] may represent the complementary sequence. The VHT-LTF sequences built for the 80 MHz channel bandwidth based on the pattern of equation (9) can provide the preferred PAPR results for different cases of non-oversampling and oversampling, if the VHT-LTF sequences comprise the interpolation sequences interp4ONull, interpδOExtraL, interpδOExtraR, and the phase rotation pattern [cl c2 c3 c4] according to figure 5i.
In one aspect of the present description, different null tone values can be used for upper and lower 40 MHz subbands in the VHT-LTF pattern defined by equation (9). In this case, the VHT-LTF standard for transmission over the 80 MHz channel can be provided as: Eq.10:


It can be seen from equation (10) that there can be three subcarriers equal to zero around the DC tone, the interpolation sequences interp4ONull, interpδOExtraL, interpδOExtraR, which can comprise additional tones to be chosen in an effort to minimize (or by the minus reduce) to PAPR, and [cl c2 c3 c4] may represent the complementary sequence. VHT-LTF sequences built for 80 MHz channel bandwidth based on the pattern of equation (10) can provide preferred PAPR results for different cases of non-oversampling and oversampling, if the VHT-LTF sequences comprise the sequences of interpolation interp4ONull, interpδOExtraL, interpδOExtraR and the phase rotation pattern [cl c2 c3 c4] according to figure 5j.
In one aspect of the present description, the VHT-LTF tone values of the VHT-LTF pattern defined by equation (10) can be replaced in the pilot tones by single-sequence pilot values 700 illustrated in Figure 7a. Additionally one or more of the P values illustrated in Fig. 7b can be applied to non-pilot tones of the VHT-LTF pattern to provide orthogonality between the different sequences of a transmitting node. PAPR results for different P values are also given in figure 7b, while 4-times oversampling with IFFT size 1024 can be applied to the transmitting node. In this case, there can be a maximum of 0.7 dB of PAPR fluctuations from one VHT-LTF symbol to another VHT-LTF symbol and from one broadcast stream to another.
In one aspect of the present description, the VHT-LTF stream can be constructed for transmission over the 80 MHz channel by using all 20 MHz 802.11a tones and 40 MHz 802.11a tones, and using different tone values null for the upper and lower 40 MHz subbands. Additionally, the VHT-LTF tone values in the pilot tones can be replaced by single-sequence pilots 700 of Figure 7a, the P value equal to "1" can be applied to the non-pilot tones by filling in the tones that are missing and applying a phase rotation on each 20 MHz subchannel. In this case, the VHT-LTF standard for transmission over the 80 MHz channel can be provided as:

A preferred 80 MHz VHT-LTF sequence with single sequence pilots 700 of Fig. 7a and P value of "1" can achieve a PAPR of 4.6138 dB (4 times oversampling with IFFT size 1024) by using phase rotation [cl c2 c3 c4] = [-1 1 1 1] and interpolation sequences [ interp4ONull, interpδOExtraL, interpδOExtraR, interp4ONullR] = [1 -1 1, 1-11 1, -1 -1 - 11, 1 -11]. The PAPR results are illustrated in Figure 7c for different P values.
In one aspect of the present description, the VHT-LTF stream can be constructed for transmission over the 80 MHz channel by using all 20 MHz 802.11a tones and 40 MHz 802.11a tones and using different null tone values for the upper and lower 40 MHz subbands. Additionally, the VHT-LTF tone values in the pilots can be replaced by single-sequence 700 pilots from Figure 7a, the P value of "-1" can be applied to non-pilot tones, by filling in the missing tones and applying a phase rotation to each 20 MHz subchannel. In this case, the VHT-LTF pattern used to build the VHT-LTF sequences can be defined as in equation (11).
A preferred 80 MHz VHT-LTF sequence with the 10 single-sequence pilots 700 of Figure 7a and the P value of "-1" can achieve a PAPR of 4,6073 dB (4 times oversampling with IFFT size 1024) by use of phase rotation [cl c2 c3 c4] = [1 1 -1 1] and interpolation sequences [ interp4ONullL, interpδOExtraL, 15 interpδOExtraR, interp4ONullR] = [1 -1 1, 1 1 -1 1, 1-11 1, -1 1 1]. The PAPR results are illustrated in figure 7d for different P values.
In one aspect of the present description, the VHT-LTF stream can be constructed for transmission over the 80 MHz channel by using all 20 MHz 802.11a tones and 40 MHz 802.11a tones and using different tone values null for the upper and lower 40 MHz subbands. Additionally, the VHT-LTF tone values in the pilot tones can be replaced by single-sequence pilots 700 from Fig. 7a, the P value of exp(-jπ/3) can be applied to non-pilot tones, with the filling in the missing tones and applying a phase rotation in each 20 MHz subchannel. In this case, a base pattern used to build the VHT-LTF sequence can be defined as in equation (11).
A preferred 80 MHz LTF sequence with the single-sequence pilots 700 of Fig. 7a and the P value of exp(-jπ/3) can achieve a PAPR of 4.8658 dB (4 times oversampling with IFFT the size of 1024) by using phase rotation [cl c2 c3 c4] = [- 1 1 1 1] and interpolation sequences [interp4ONullL, interpδOExtraL, interpδOExtraR, interp4ONullR] = [1 -1 1, 1 -1 -1 1, 1 -111, 1-1 1]. The PAPR results are illustrated in Figure 7e for different P values.
In one aspect of the present description, the VHT-LTF stream can be constructed for transmission over the 60 MHz channel by using all 20 MHz 802.11a tones and 40 MHz 802.11a tones, and using different tone values null for the upper and lower 40 MHz subbands. Additionally, the VHT-LTF tone values in the pilot tones can be replaced by single-sequence pilots 700 from Figure 7a, the P value of exp(-j2π/3) can be applied to non-pilot tones, with padding of tones that are missing and application of a phase rotation in each 20 MHz subchannel. In this case, a base pattern used to build the VHT-LTF sequences can be defined as in equation (11).
A preferred 80 MHz VHT-LTF sequence with single sequence pilots 700 of Fig. 7a and the P value of exp(-j2π/3) can achieve a PAPR of 4.8248 dB (4 times oversampling with IFFT the size of 1024) by using phase rotation [cl c2 c3 c4] = [ 11-11] and interpolation sequences [interp4ONullL, interpδOExtraL, interpδOExtraR, interp4ONullR] = [1 -1 1, 1 1-11, 1-11 1, -1 1 1] . The PAPR results are illustrated in Figure 7f for different P values.
In one aspect of the present description, the VHT-LTF stream can be constructed for transmission over the 80 MHz channel by using all 20 MHz 802.11a tones and 40 MHz 802.11a tones, and using different tone values null for the upper and lower 40 MHz subbands. Additionally, the VHT-LTF tone values in the pilot tones can be replaced by single-sequence pilots 700 from Figure 7a, the P value of exp(-j4π/3) can be applied to non-pilot tones, with tone padding that are missing and application of a phase rotation in each 20 MHz subchannel. In this case, a base pattern used to build the VHT-LTF sequences can be defined as in equation (11).
A preferred 80 MHz VHT-LTF sequence with single sequence pilots 700 of Figure 7a and the P value of exp(-j4π/3) can achieve a PAPR of 4.8248 dB (4 times oversampling with IFFT the size of 1024) by using phase rotation [cl c2 c3 c4] = [1 1 -1 1] and interpolation sequences [interp4ONullL, interpδOExtraL, interpδOExtraR, interp4ONullR] = [1 -1 1, 1 1 -1 1, 1- 11 1, -1 1 1]. The PAPR results are illustrated in Figure 7g for different P values.
In one aspect of the present description, the VHT-LTF stream can be constructed for transmission over the 80 MHz channel by using all 20 MHz 802.11a tones and 40 MHz 802.11a tones, and using different null tone values for the sub-bands. 40 MHz top and bottom. Additionally, the VHT-LTF tone values in the pilot tones can be replaced by single-sequence pilots 700 from Figure 7a, the P value of exp(-j5π/3) can be applied to non-pilot tones by filling in the tones that are lacking and application of a phase rotation in each 20 MHz subchannel. In this case, a base pattern used for the construction of the VHT-LTF sequences can be defined as in equation (11).
A preferred 80 MHz VHT-LTF sequence with single-sequence pilots 700 of Fig. 7a and P value of exp(-j5π/3) can achieve a PAPR of 4.8658 dB (4 times oversampling with IFFT size 1024) by using phase rotation [cl c2 c3 c4] = [-1 1 1 1] and interpolation sequences [ interp4ONullL, interpδOExtraL, interpδOExtraR, interp4ONullR] =1-11, 1 -1, -1 1, 1-11 1 , 1-1 1]. The PAPR results are illustrated in Figure 7h for different P values.
In one aspect of the present description, the VHT-LTF sequence can be constructed for transmission over the 80 MHz channel by using the entire 802.lln 40 MHz tones in both 40 MHz subchannels, where the VHT- tone values LTF in the pilot tones can be replaced by single-sequence 700 pilots from Figure 7a, filling in the missing tones and applying a rotation phase on each 20 MHz subchannel in an effort to minimize a larger PAPR (this is, the worst-case PAPR result) via various P values applied to the non-pilot tones, ie,
where S represents all possible VHT-LTF sequences derived from the pattern defined by equation (11). VHT-LTF sequences for transmission over the 80 MHz channel can be constructed based on the pattern defined in equation (11).
A preferred 80 MHz VHT-LTF sequence can achieve a minimum (maximum) worst case PAPR of 5.0722 dB (4 times oversampling with IFFT size 1024) across multiple P values by using the rotation pattern [cl c2 c3 c4] = [-1 1 1 1] and interpolation sequences [interp4ONullL, interpδOExtraL, interpδOExtraR, interp4ONullR] = [-1 1 1, -1 -1 1 -1, 1-1 -1 1, -1 1] . The PAPR results are illustrated in Figure 7i for different P values.
In one aspect of the present description, the sequence of values 700 may not be applied to the pilot tones, while different P values may be applied to all tones of the VHT-LTF pattern defined by equation (11). In that case, the PAPR results may be the same as the base VHT-LTF sequence without applying the P values.
In one aspect of the present description, the non-pilot tones of the VHT-LTF sequence can be multiplied by one or more P values (i.e., one or more elements of a P matrix), and pilot tones of the VHT-LTF sequence can be multiplied by one or more R values (that is, one or more elements of an R matrix) . Any applied P value other than the applied R value can change the base VHT-LTF sequence. Therefore, different P and R values can result in different PAPR. Optimization of the VHT-LTF sequence can be performed by finding a sequence that minimizes a maximum PAPR across all possible values of P and R, that is,
where S can represent sequences for all possible additional pitch values and phase rotations per 20 MHz subband. In one aspect, the PAPR level can only depend on a product of P and R values. For example, { P, R] = {exp(jcp),l} and {P, R} = {-exp(jcp), -1} can give the same VHT-LTF sequence rotated by 180 degrees.
In one aspect, optimization of the VHT-LTF sequence can be performed without using the unique 700 sequence values in the pilot tones. The VHT-LTF stream can be constructed for transmission over the 800 MHz channel by using all 802.lln .40 MHz tones on both 40 MHz subchannels by filling in missing tones and applying a phase rotation on each 20 MHz subchannel. In this case, the VHT-LTF standard can be set to:
where interp4ONullL (3 tones), interpδOExtraL (4 tones), interpδOExtraR (4 tones), interp4ONullR (3 tones) are additional tones, while interp4ONullL and interp40NullR may not need to be identical; [cl c2 c3 c4] is the phase rotation pattern comprising {+/-1, +/-j} values. Missing pitch values and rotation pattern can be optimized for better PAPR.
A preferred VHT-LTF sequence constructed for transmission over the 80 MHz channel based on the pattern defined by equation (14) can achieve a PAPR of 4.48 dB (4 times oversampling with IFFT size 1024) by using the pattern of phase rotation [cl c2 c3 c4] = [11-11], or alternatively [-1 -1 1 -1], [jj ~jj], [-j ~j 3 “j]< as the interpolation sequences can be [interp40NullL, interp80ExtraL, interpδOExtraR, interp4ONullR] = [111, -1 -1 -1 1, 1 -1 -1 -1 , 1 -1 ]. The entire VHT-LTF pattern (excluding phase rotation per 20 MHz subchannel) is illustrated in Figure 8a, where each row of bit pattern 802 can correspond to one of the four 20 MHz subchannels. The 80 VHT-LTF pattern 802 MHz may be 0.24 dB better in PAPR than the ideal standard from the constraint search space considering equal null tone values for the upper and lower 40 MHz subbands.
In another aspect of the present description, optimization of the VHT-LTF sequence can be performed by applying single sequence values 700 in pilot tones. The VHT-LTF sequence can be constructed for the 80 MHz channel by using all 802 tones. lln of 40 MHz on both 40 MHz subchannels, replacing the tone values in the pilot tones with the single sequence pilots 700 of the figure 7a, with filling in the missing tones and applying a phase rotation in each 20 MHz subchannel. In this case, the constructed VHT-LFT pattern can be defined as:
where interp40NullL (3 tones), interpδOExtraL (4 tones), interpδOExtraR (4 tones), interp4ONullR (3 tones) are additional tones, while interp4ONullL and interp4ONullR need not be identical; [cl c2 c3 c4] is the phase rotation pattern comprising {+/—1, +/-j} values. Missing pitch values and rotation pattern can be optimized for the best PAPR.
A preferred VHT-LTF sequence constructed for transmission over the 80 MHz channel based on the pattern defined by equation (15) may have a minimum worst-case PAPR of 5,0722 dB (4 times oversampling with IFFT size 1024) across of all values of P and R by using the phase rotation pattern [cl c2 c3 c4] = [-1 1 1 1], or alternatively [1 -1 -1 -1] , [-jjjj] , [j -j -j -j], where the interpolation sequences can be [ interp4ONullL, interpδOExtraL, interpδOExtraR, interp4ONullR] = [-1 1 1, -1 -1 1 -1, 1 -1 -1 1, 1 -1 1 ] . The entire VHT-LTF pattern (excluding phase rotation per 20 MHz subchannel) is illustrated in Figure 8b, where each row of bit pattern 804 can correspond to one of the four 40 MHz subchannels. For the preferred VHT-LTF sequence , the product of applied P and R values can be equal to exp(-j2π/3) or exp(-j4π/3). In another aspect of the present description, optimization of the VHT-LTF sequence can be performed by using a new pilot pattern. The pilot values can be the same as the HT-LTF (High Throughput Long Sequencing Field) values in the pilot tones. In this case, the 80 MHz subcarrier sequence for VHT-LTF can be constructed by using all 802. lln tones of 40 MHz in both 40 MHz subchannels, filling in missing tones and applying a rotation of phase on each 20 MHz subchannel. The constructed VHT-LTF pattern can be defined as: Eq.15: Eq.16:
where interp4ONullL (3 tones), interpδOExtraL (4 tones), interpδOExtraR (4 tones), interp4ONullR (3 tones) are additional tones, while interp40NullL, and interp4ONullR may not need to be identical; [cl c2 c3 c4] is the phase rotation pattern comprising values {+/- -1, +/- j}. Missing pitch values and rotation pattern can be optimized for better PAPR.
A preferred VHT-LTF sequence built for transmission over the 60 MHz channel based on the pattern defined by equation (16) may have a minimum worst case PAPR of 5.2070 dB (4 times oversampling with size 1024 IFFT ) through all the values of P and R by using the phase rotation [cl c2 c3 c4] = [-1 111], or alternatively [1 -1 -1 -1], [-jjjj] , [j ”j “j -j]t while the interpolation sequences can be [interp4ONullL, interpδOExtraL, interpδOExtraR, interp4 ONullR] = [1 -1 1, 1 -1 1 -1, 1 -1 -1 1, 1 -1 1]. The entire VHT-LTF pattern (excluding subchannel rotation by 20 MHz) is illustrated in Figure 6c, where each row of bit pattern 606 can correspond to one of four 20 MHz subchannels. For the preferred VHT-LTF sequence, the product of applied P and R values can be equal to exp(-j2π/3) or exp(-j4π/3).
Figure 9 illustrates illustrative operations 900 for constructing the VHT-LTF sequence for transmission over the 80 MHz channel in accordance with certain aspects of the present description. In one aspect, operations 900 may be performed at access point 110 of wireless communication system 100 of Figure 1. At 902, the VHT-LTF sequence may be constructed by combining a plurality of interpolation sequences with the values of LTF tone associated with at least one of the IEEE 802.lln wireless communications standard or the IEEE 802.11a wireless communications standard, where the LTF tone values can cover at least a portion of the bandwidth of a first size and each one of the LTF tone values may be repeated one or more times for different subcarriers. In 904, the tone phases of the VHT-LTF sequence can be rotated by bandwidth of the first size (eg with different values of cl, c2, c3 and c4 of the rotation patterns [cl c2 c3 c4] applied by sub -20 MHz band) in an effort to minimize (or at least reduce) PAPR during a VHT-LTF stream. Additionally, the phases of a plurality of tones of the LTF sequence may be rotated in an effort to reduce PAPR, where the plurality of tones may belong to a portion of the bandwidth of a second size. At 906, the tones of the VHT-LTF sequence at the pilot sites can be replaced with a sequence of values (eg, with the 700 sequence of Figure 7a) chosen in an effort to reduce the PAPR.
In one aspect of the present description, VHT-LTF sequence tones at non-pilot locations may be multiplied by one or more values (eg, P values), while VHT-LTF sequence tones at pilot locations may be multiplied by one or more other values (e.g., R values), where one or more values and one or more other values may be determined in an effort to reduce a greater PAPR among all PAPR results associated with the transmission of the VHT-LTF sequence.
The constructed VHT-LTF sequence can be transmitted over a wireless channel by using bandwidth of the second size. In an aspect of the present description, the bandwidth of the first size may comprise at least one of a bandwidth of 20 MHz or a bandwidth of 40 MHz and the bandwidth of the second size may comprise a bandwidth of 80 MHz. Phase Rotation Pattern for Legacy Part of Preamble
Referring again to Fig. 4, certain aspects of the present description support various options for designing the L-LTF 406 and L-STF 404 of the legacy portion 402 of preamble 400 in an effort to reduce PAPR at a transmitting node. The legacy part of the preamble may comprise a part of the preamble that is recognized by the communicating wireless nodes in accordance with past and future wireless communications standards.
Certain aspects of the present description support various cases of how a complementary phase rotation sequence can be designed in an effort to reduce PAPR while transmitting at least one of the L-LTF and L-STF. In the first case, the phase rotation pattern can be given as c = [c(1) c(2) c(3) c(4)], where c(i) = 1, -1, j, -j . This rotation pattern can have a potential coexistence detection issue, depending on the implementation. In the second case, the phase rotation pattern can be given as c = [a a* j b b*)], where a, b = 1, 01, j, -j. In that case, there may be no coexistence detection problem. In the third case, the phase rotation pattern can be given as c = [ 1 j and d] , where e, d = 1, -1, j, - j, except that d = e* j . This rotation pattern can also have a potential coexistence detection issue, depending on the implementation. In the fourth case, the phase rotation pattern can be given as c = [ 1 j b b*j], where b can have any complex number. In that case, there may be no coexistence detection issues.
Figure 10a illustrates exemplary minimum PAPR results for each of the four aforementioned cases of phase rotation pattern design to construct the L-LTF sequence in accordance with certain aspects of the present disclosure. It can be seen from Figure 10a that the best PAPR result of 5.3962 dB can be achieved for the phase rotation pattern c = [c(1) c(2) c(3) c(4)] = [-1 111].
Figure 10b illustrates the illustrative minimum PAPR results for each of the four aforementioned cases of phase rotation pattern design for L-STF sequence construction in accordance with certain aspects of the present disclosure. It can be seen from Figure 10b that the best PAPR result of 4.3480 dB can be achieved for the rotation pattern c = [c(l) c(2) c(3) c(4)] =[- 111 1] or c=[c(1) c(2) c(3) c(4)] [111-1] •
It can be seen from figures 10a and 10b that, for both L-LTF and L-STF sequences, the same phase rotation pattern of c = [c(1) c(2) c(3) c(4 )] = [-1 1 1 1] may give the best PAPR result. Additionally, the phase rotation pattern c = [1 jed] (ie the third case) can result in a slightly worse PAPR (ie less than 0.2, according to figure 10a and figure 10b) by using rotation patterns [1 j -1 j] or [ 1 j 1 - j ] . Additionally, the same phase rotation patterns applied to tones of at least one of the L-STF or L-LTF (for example, the phase rotation pattern of c = [-1 111] may also be applicable to modify the phases. of the tones in at least one of the L-SIG field 408 or the VHT-SIG-A fields 410, 412 of the legacy portion 402 of the preamble 400 illustrated in Fig. 4 to achieve the preferred PAPR results.
In summary, the present description provides a method and apparatus for constructing VHT-LTF sequences for transmission over the 80 MHz channel in an effort to provide preferred PAPR results at a transmission node. VHT-LTF sequences can be constructed using at least one of the LTF 802.lln values of 40 MHz, the LTF 802.lln values of 20 MHz, or the LTF 802.11a values of 20 MHz, with the chosen phase rotation suitably per 20 MHz subband and with the additional subcarrier values suitably chosen in an effort to minimize (or at least reduce) the PAPR.
The same approach mentioned above for constructing the VHT-LTF sequences for the 80 MHz channel bandwidth can also be used for other numbers of subcarriers. In one aspect of the present description, to support the IEEE 802.11ac wireless communication standard, few tones at the band edges can be zeroed. In another aspect, all tones around DC can be used.
The various operations of the methods described above can be performed by any suitable means capable of performing the corresponding functions. The means can include various hardware and/or software components and/or modules, including, but not limited to, a circuit, an ASIC, or processor. Generally, where there are operations illustrated in the figures, these operations may have corresponding means plus function components with similar numbering. For example, operations 900 shown in Figure 9 correspond to components 900a shown in Figure 9a.
As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" may include calculating, computing, processing, deriving, investigating, querying (for example, querying a table, database, or other data structure), determining, and the like. In addition, "determining" may include receiving (for example, receiving information), accessing (for example, accessing data in memory) or the like. Furthermore, "determining" may include solving, selecting, choosing, establishing, and the like.
As used here, a phrase referring to "at least one of" a list of items refers to any combination of those items, including singular elements. As an example, "at least one of: a, b, or c" must cover: a, b, c, a-b, a-c, b-c, and a-b-c.
The various operations of the methods described above can be performed by any suitable means capable of carrying out the operations, such as various hardware and/or software components, circuits and/or modules. Generally, any operation illustrated in the figures can be carried out by corresponding functional means capable of carrying out the operations.
For example, the construction means may comprise an application-specific integrated circuit, for example, a TX data processor 202 of wireless node 200 of Fig. 2 or a processor 304 of processing system 300 of Fig. 3. The means for rotation may comprise an application-specific integrated circuit, e.g., the TX data processor 202 of the wireless node 200 or the processor 304 of the processing system 300. The means for replacing may comprise an application-specific integrated circuit, e.g. TX data processor 202 of wireless node 200 or processor 304 of processing system 300. The transmitting means may comprise a transmitter, e.g., transceiver 206 of wireless node 200. The designating means may comprise an integrated circuit application-specific, for example, data processor TX 202 of wireless node 200 or processor 304 of processing system 300. The means for performing sampling The multiplying means may comprise a sampling circuit, for example, the transceiver 206 of the wireless node 200. The multiplying means may comprise an application-specific integrated circuit, for example, the data processor TX 202 of the wireless node 200 or the processor 304 of processing system 300. The means for utilizing may comprise an application-specific integrated circuit, for example, the TX data processor 202 of the wireless node 200 or the processor 304 of the processing system 300. The means for modifying may comprise an application-specific integrated circuit, for example, data processor TX 202 of wireless node 200 or processor 304 of processing system 300.
The various illustrative logic blocks, modules and circuits described in connection with the present description can be implemented or realized with a general purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an assembly signal a field-programmable gate (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 here. A general purpose processor can be a microprocessor, but in the alternative, 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 similar configuration.
The steps of a method or algorithm described in relation to the present description can be directly embodied in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside on any form 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, hard disk, removable disk, CD-ROM and so on. against. A software module can comprise a single instruction, or many instructions, and can be distributed across several different code segments, between different programs, and across multiple storage media. A storage medium can be coupled to a processor so that the processor can read information from and write information to the storage medium. Alternatively, the storage medium can be integral with the processor.
The methods described here comprise one or more steps or actions to achieve the described method. The method steps and/or actions can be interchanged with one another without straying 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 the specific steps and/or actions can be modified without departing from the scope of the claims.
The functions described can be implemented in hardware, software, firmware or any combination thereof. If implemented in software, the functions can be stored or transmitted as one or more instructions or code in a computer-readable medium. Computer readable media includes both computer storage media and communication media including any medium that facilitates the transfer of a computer program from one place to another. A storage medium can be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer readable media may comprise 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 that can be accessed by a computer. Furthermore, any connection is properly called a computer readable medium. For example, if the software is transmitted from a network site, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR), radio and microwave, so coaxial cable, fiber optic cable, twisted pair, DSL or wireless technologies such as infrared, radio and microwave are included in the definition of medium. Floppy disk and disk, as used herein, include CD, laser disk, optical disk, DVD, floppy disk, and Blu-ray disk, where floppy disks normally reproduce data magnetically, while disks reproduce data optically with lasers. Thus, in some respects computer-readable media can comprise non-transient computer-readable media (eg, tangible media). Additionally, for other aspects computer readable media may comprise transient computer readable media (e.g., a signal). Combinations of the above should also be included in the scope of computer readable media.
Thus, certain aspects can comprise a computer program product to perform the operations presented here. For example, such computer program product may comprise a computer-readable medium having 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.
Software or instructions can also be transmitted over a transmission medium. For example, if the software is transmitted from a web site, server or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) or wireless technologies such as infrared, radio and microwave, so 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.
Additionally, it should be appreciated that modules and/or other means suitable for carrying out the methods and techniques described herein may be downloaded and/or otherwise retrieved 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 for carrying out the methods described herein. Alternatively, various methods described here can be provided via the storage media (eg RAM, ROM, a physical storage medium such as a CD or floppy disk, etc.) such that a user terminal and/or base station can obtain the various methods by attaching or providing storage media to the device. Furthermore, any other technique suitable for providing the methods and techniques described here for a device can be used.
It should be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made to 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 description, other additional aspects of the description can be glimpsed without departing from the basic scope of the same, and the scope is determined by the claims that follow.

权利要求:
Claims (15)
[0001]
1. Method for wireless communication, characterized in that it comprises: constructing (902) a long training field sequence, LTF, from a preamble by combining a plurality of interpolation sequences with LTF tone values associated with at least one from the IEEE 802.11n standard and the IEEE 802.11a standard, where: the LTF tone values cover at least a portion of the bandwidth of a first size; and each of the LTF pitch values is repeated one or more times for different subcarriers; rotating (904) phases of tones of the LTF sequence by bandwidth of the first size in an effort to reduce a peak-to-average power ratio, PAPR, during an LTF sequence transmission; and replacing (906) tones of the LTF sequence at the pilot locations with a defined stream of chosen values in an effort to reduce PAPR.
[0002]
2. Method according to claim 1, characterized in that it further comprises: transmitting the LTF sequence within the preamble through a wireless channel using a bandwidth of a second size; or transmitting the LTF sequence within the preamble over a wireless channel when using a bandwidth of 80 MHz; or rotating phases of a plurality of tones of the LTF sequence in an effort to reduce PAPR, wherein the plurality of tones belong to a portion of the bandwidth of the second size; or perform oversampling before transmitting the LTF stream; or using different null-tone values in different parts of a bandwidth associated with transmitting the LTF sequence, wherein each part of the bandwidth comprises a 40 MHz band.
[0003]
3. Method according to claim 1, characterized in that constructing the LTF sequence comprises: designing the plurality of interpolation sequences in an effort to reduce the PAPR; or wherein the bandwidth of the first size comprises at least a 20 MHz band or a 40 MHz band; or wherein the LTF sequence comprises at most three pitch values equal to zero in the subcarriers around the DC subcarrier.
[0004]
4. Method according to claim 1, characterized in that it further comprises: multiplying tones of the LTF sequence in the non-pilot locations with one or more values; and multiplying tones of the LTF sequence at the pilot locations with one or more other values; where the one or more values and the one or more other values are determined in an effort to reduce a larger PAPR among all PAPR results associated with the transmission of the LTF sequence.
[0005]
5. Method according to claim 1, characterized in that it further comprises: modifying tonal phases of at least one of a Legacy Long Training Ground, L-LTF, or a Legacy Short Training Ground, L -STF, within a legacy part of the preamble using one or more phase rotation patterns, where: o the one or more phase rotation patterns are determined in an effort to reduce a PAPR while transmitting at least one of an L-LTF or L-STF; and the legacy part of the preamble comprises a part of the preamble recognizable by the apparatus communicating in accordance with previous and current wireless communication standards.
[0006]
6. The method of claim 1, further comprising: modifying tone phases of a preamble legacy part using one or more phase rotation patterns, wherein: the preamble legacy part comprises at least one of a Legacy Short Training Ground, L-LTF, a Legacy Long Training Ground, L-STF, a Legacy Signal field, L-SIG, or a Type A Very High Throughput Signal field High, VHT-SIG-A; o one or more phase rotation patterns are determined in an effort to reduce a PAPR during preamble transmission; and the legacy part of the preamble comprises a part of the preamble recognizable by the apparatus communicating in accordance with previous and current wireless communication standards.
[0007]
7. Apparatus for wireless communications, characterized in that it comprises: mechanisms (902A) for constructing a long training field sequence, LTF, from a preamble by combining a plurality of interpolation sequences with LTF tone values associated with the fur. less one of an IEEE 802.11n standard or an IEEE 802.11a standard, wherein: the LTF tone values cover at least a portion of the bandwidth of a first size; and each of the LTF pitch values is repeated one or more times for different subcarriers; mechanisms (904A) for rotating the tone phases of the LTF sequence by bandwidth of the first size in an effort to reduce a peak-to-average power ratio, PAPR, during a transmission of the LTF sequence; and mechanisms (906A) to replace LTF sequence tones at pilot locations with a defined stream of chosen values in an effort to reduce PAPR.
[0008]
8. Apparatus according to claim 7, characterized in that it further comprises: mechanisms for transmitting the LTF sequence within the preamble via a wireless channel by using a bandwidth of a second size; or mechanisms for transmitting the LTF sequence within the preamble over a wireless channel by using a bandwidth of 80 MHz.
[0009]
9. Apparatus according to claim 7, characterized in that the mechanisms for constructing the LTF sequence comprise: mechanisms for designating the plurality of interpolation sequences in an effort to reduce PAPR; or wherein the bandwidth of the first size comprises at least one of the 20 MHz band or the 40 MHz band; or wherein the LTF sequence comprises at most three pitch values equal to zero in the subcarriers around the DC subcarrier.
[0010]
10. Apparatus according to claim 7, CHARACTERIZED by the fact that it further comprises: mechanisms for rotating phases of a plurality of tones of the LTF sequence in an effort to reduce the PAPR, wherein the plurality of tones belong to a part of the bandwidth of the second size; or mechanisms to perform oversampling before transmitting the LTF sequence; or mechanisms for using different null-tone values in different parts of a bandwidth associated with transmitting the LTF sequence, wherein each part of the bandwidth comprises the 40 MHz band.
[0011]
11. Apparatus according to claim 7, characterized in that it further comprises: mechanisms for multiplying the tones of the LTF sequence in non-pilot locations with one or more values; and mechanisms for multiplying tones of the LTF sequence at pilot locations with one or more other values; where the one or more values and the one or more other values are determined in an effort to reduce a greater PAPR among all PAPR results associated with the transmission of the LTF sequence.
[0012]
12. Apparatus according to claim 7, characterized in that it further comprises: mechanisms for modifying the tone phases of at least one of a Long Training Ground, L-LTF, or Short Legacy Training Ground, L -STF, within a legacy part of the preamble using one or more phase rotation patterns, where: the one or more phase rotation patterns are determined in an effort to reduce a PAPR while transmitting at least one of L-LTF and L-STF; and the legacy part of the preamble comprises a preamble part recognizable by apparatus communicating in accordance with previous, current and future wireless communications standards.
[0013]
13. Apparatus according to claim 7, characterized in that it further comprises: mechanisms for modifying the tone phases of a legacy part of the preamble using one or more phase rotation patterns, wherein: the legacy part of the preamble comprises at least one of a Short Legacy Training Ground, L-LTF, a Long Legacy Training Ground, L-LTF, a Legacy Signal Field, L-SIG, or a Type A Signal field Very High Transfer Rate, VHT-SIG-A; o one or more phase rotation patterns are determined in an effort to reduce a PAPR during preamble transmission; and the legacy part of the preamble comprises a part of the preamble recognizable by apparatus communicating in accordance with previous, current and future wireless communication standards.
[0014]
14. Memory, characterized in that it comprises instructions stored therein, the instructions being executed by a computer to carry out the method as defined in any one of claims 1 to 6.
[0015]
15. Access point, characterized by the fact that it comprises: at least one antenna; a first circuit configured to construct a long training field sequence, LTF, from a preamble by combining a plurality of interpolation sequences with the LTF tone values associated with at least one of an IEEE 802.11n standard or an IEEE 802.11a standard , where: the LTF tone values cover at least a portion of the bandwidth of a first size; and each of the LTF pitch values is repeated one or more times for different subcarriers; a second circuit configured to rotate the tone phases of the LTF sequence by bandwidth of the first size in an effort to reduce a peak-to-average power ratio, PAPR, during an LTF sequence transmission; a third circuit configured to replace LTF sequence tones at pilot locations with a defined stream of chosen values in an effort to reduce PAPR; and a transmitter configured to transmit, via at least one antenna, the LTF sequence within the preamble via a wireless channel using a bandwidth of a second size.

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法律状态:
2018-12-26| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|

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2020-02-11| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-07-06| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-09-14| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 06/04/2011, OBSERVADAS AS CONDICOES LEGAIS. PATENTE CONCEDIDA CONFORME ADI 5.529/DF, QUE DETERMINA A ALTERACAO DO PRAZO DE CONCESSAO. |

优先权:

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申请号 | 申请日 | 专利标题

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US32133010P| true| 2010-04-06|2010-04-06|

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US61/321,330|2010-04-06|

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US32175210P| true| 2010-04-07|2010-04-07|

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US61/321,752|2010-04-07|

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US32377510P| true| 2010-04-13|2010-04-13|

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US33236010P| true| 2010-05-07|2010-05-07|

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US61/332,360|2010-05-07|

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US33316810P| true| 2010-05-10|2010-05-10|

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US33426010P| true| 2010-05-13|2010-05-13|

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US34834910P| true| 2010-05-26|2010-05-26|

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US35021610P| true| 2010-06-01|2010-06-01|

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US61/350,216|2010-06-01|

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US35489810P| true| 2010-06-15|2010-06-15|

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US13/037,915|2011-03-01|

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PCT/US2011/031449|WO2011127193A1|2010-04-06|2011-04-06|Method and apparatus for constructing very high throughput long training field sequences|

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