Source: https://patents.justia.com/patent/10181966
Timestamp: 2019-08-19 09:52:37
Document Index: 83556814

Matched Legal Cases: ['Application No. 62', 'Application No. 62', 'Application No. 62', 'art 15', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11']

US Patent for WiFi classification by pilot sequences Patent (Patent # 10,181,966 issued January 15, 2019) - Justia Patents Search
Justia Patents Generalized Orthogonal Or Special Mathematical TechniquesUS Patent for WiFi classification by pilot sequences Patent (Patent # 10,181,966)
Apr 29, 2016 - Marvell International Ltd.
A communication device determines a format according to which a data unit is to be generated, and selects a pilot sequence to be used for generating the data unit. The pilot sequence is selected from a plurality of pilot sequences corresponding to a plurality of data unit formats, and the pilot sequence is selected based on the determined format. The communication device generates the data unit to include the selected pilot sequence, and transmits the data unit.
This application claims the benefit of U.S. Provisional Patent Application No. 62/156,076, entitled “WiFi Classification by Pilot Sequences,” filed on May 1, 2015, and U.S. Provisional Patent Application No. 62/218,309, entitled “Physical Layer Frame Format for WLAN,” filed on Sep. 14, 2015, the disclosures of which are incorporated herein by reference in their entireties.
The present disclosure relates generally to communication networks and, more particularly, to wireless local area networks that utilize multiple communication protocols and/or data unit formats.
In an embodiment, a method includes: determining, at a communication device, a format according to which a data unit is to be generated, and selecting, at the communication device, a pilot sequence to be used for generating the data unit. The pilot sequence is selected from a plurality of pilot sequences corresponding to a plurality of data unit formats, and the pilot sequence is selected based on the determined format. The method also includes: generating, at the communication device, the data unit to include the selected pilot sequence, and transmitting, by the communication device, the data unit.
In another embodiment, an apparatus comprises a network interface device having one or more integrated circuits (ICs). The one or more ICs are configured to: determine a format according to which a data unit is to be generated, and select a pilot sequence to be used for generating the data unit. The pilot sequence is selected from a plurality of pilot sequences corresponding to a plurality of data unit formats, and the pilot sequence is selected based on the determined format. The one or more ICs are further configured to: generate the data unit to include the selected pilot sequence, and transmit the data unit.
In yet another embodiment, a method includes: receiving, at a communication device, a data unit via a communication channel, and determining, at the communication device, a pilot sequence in the received data unit. The method also includes: identifying, at the communication device, the pilot sequence in the received data unit from a plurality of pilot sequences corresponding to a plurality of data unit formats, and determining, at the communication device, a format of the received data unit corresponding to the identified pilot sequence. The method further includes processing, at the communication device, the received data unit according to the determined format.
In still another embodiment, an apparatus comprises a network interface device having one or more integrated circuits (ICs). The one or more ICs are configured to: receive a data unit via a communication channel, and determine a pilot sequence in the received data unit. The one or more ICs are also configured to identify the pilot sequence in the received data unit from a plurality of pilot sequences corresponding to a plurality of data unit formats, and determine a format of the received data unit based on the identified pilot sequence. The one or more ICs are further configured to process the received data unit according to the determined format.
FIG. 1 is a block diagram of an example wireless communication network in which communication devices utilize pilot sequences to determine formats of data units, according to an embodiment.
FIG. 2A is a diagram of a prior art physical layer (PHY) protocol data unit that one or more communication devices in the network of FIG. 1 are configured to transmit.
FIG. 2B is a diagram of a media access control (MAC) protocol data unit that is included in the data field of the PHY data unit of FIG. 2A.
FIG. 3 is a diagram of another prior art PHY data unit that one or more communication devices in the network of FIG. 1 are configured to transmit, according to an embodiment.
FIG. 4 is a diagram of another prior art PHY data unit that one or more communication devices in the network of FIG. 1 are configured to transmit, according to an embodiment.
FIG. 5 is a diagram of yet another prior art PHY data unit that one or more communication devices in the network of FIG. 1 are configured to transmit, according to an embodiment.
FIG. 6 is a diagram of an example PHY data unit that one or more communication devices in the network of FIG. 1 are configured to transmit, according to an embodiment.
FIG. 7 is a diagram illustrating orthogonal frequency division multiplexing (OFDM) symbols having pilot signals on some OFDM subcarriers as specified by a prior art communication protocol.
FIG. 8 is a diagram illustrating an example data unit including an example pattern of pilot signals that indicates a format of the data unit, according to an embodiment.
FIG. 9 is a diagram illustrating another example data unit including another example pattern of pilot signals that indicates a format of the data unit, according to an embodiment.
FIG. 10 is a diagram illustrating another example data unit including another example pattern of pilot signals that indicates a format of the data unit, according to an embodiment.
FIG. 11 is flow diagram of an example method for generating and transmitting a data unit having a pattern of pilot signals that indicates a format of the data unit, according to an embodiment.
FIG. 12 is flow diagram of an example method for processing a data unit having a pattern of pilot signals that indicates a format of the data unit, according to an embodiment.
In embodiments described below, a wireless network device such as an access point (AP) or client station (STA) of a wireless local area network (WLAN) generates a data unit for transmission over a communication channel. The data unit includes a pilot sequence that is used for phase and frequency tracking, and channel estimation purposes, according to some embodiments. In some embodiments, the pilot sequence is configured to indicate a format of the data unit so that a receiver of the data unit can determine the format of the data unit using the pilot sequence. In some embodiments, the AP or the STA generates a WLAN orthogonal frequency division multiplexing (OFDM) data unit with a pilot sequence transmitted over pilot subcarriers of the communication channel. In an embodiment, a transmitter selects, based on a format of a data unit to be transmitted, a pilot sequence corresponding to the format of the data unit. In an embodiment, a receiver determines a format of a received data unit based on a pilot sequence of the received data unit. In some embodiments and/or scenarios, a pilot sequence is across multiple OFDM symbols of a data unit. In other embodiments and/or scenarios, a pilot sequence is over multiple pilot subcarriers in one OFDM symbol of a data unit.
In embodiments described below, a pilot sequence in a data unit is used to distinguish amongst different data unit formats corresponding to different communication protocols. In other embodiments, a pilot sequence is used to distinguish amongst different data unit formats of defined by a single communication protocol.
In various embodiments, the MAC processor 18 and the PHY processor 20 are configured to operate according to a first communication protocol. In some embodiments, the first communication protocol defines a plurality of different data unit formats (e.g., PHY data unit formats). In some embodiments, the first communication protocol defines a single data unit format (e.g., a single PHY data unit format). In some embodiments, the MAC processor 18 and the PHY processor 20 are also configured to operate according to a second communication protocol that defines one or more data unit formats (e.g., one or more PHY data unit formats) that are different than one or more data units formats defined by the first communication protocol. In some embodiments, the MAC processor 18 and the PHY processor 20 are additionally configured to operate according to a third legacy communication protocol, and/or a fourth legacy communication protocol (e.g., according to the IEEE 802.11 ac Standard and/or the IEEE 802.11n Standard).
The WLAN 10 includes a plurality of client stations 25. Although four client stations 25 are illustrated in FIG. 1, the WLAN 10 includes other suitable numbers (e.g., 1, 2, 3, 5, 6, etc.) of client stations 25 in various scenarios and embodiments. At least one of the client stations 25 (e.g., client station 25-1) is configured to operate at least according to the first communication protocol. In some embodiments, at least one of the client stations 25 (e.g., client station 25-1) is configured to operate at least according to the first communication protocol and according to the second communication protocol. In some embodiments, at least one of the client stations 25 is not configured to operate according to the first communication protocol but is configured to operate according to at least one of the third communication protocol and/or the fourth communication protocol (referred to herein as a “legacy client station”).
According to an embodiment, the client station 25-4 is a legacy client station, i.e., the client station 25-4 is not enabled to receive and fully decode a data unit that is transmitted by the AP 14 or another client station 25 according to the first communication protocol. Similarly, according to an embodiment, the legacy client station 25-4 is not enabled to transmit data units according to the first communication protocol. In some embodiments, the legacy client station 25-4 also is not enabled to receive and fully decode, as well as transmit, data units according to the second communication protocol. In some embodiments, the legacy client station 25-4 is enabled to receive and fully decode, as well as transmit, data units according to the second communication protocol. In some embodiments, the legacy client station 25-4 is enabled to receive and fully decode and transmit data units according to the third communication protocol and/or the fourth communication protocol, in some embodiments.
In various embodiments, the MAC processor 18 and/or the PHY processor 20 of the AP 14 are configured to generate data units conforming to the first communication protocol and/or data units conforming to the second communication protocol. The transceiver(s) 21 is/are configured to transmit the generated data units via the antenna(s) 24. Similarly, the transceiver(s) 21 is/are configured to receive data units via the antenna(s) 24. In some embodiments, the MAC processor 18 and/or the PHY processor 20 of the AP 14 are configured to process received data units conforming to the first communication protocol and having different data unit formats defined by the first communication protocol, and to determine that such data units conform to the various data unit formats of the first communication protocol, according to various embodiments. In some embodiments, the MAC processor 18 and the PHY processor 20 of the AP 14 are configured to process received data units conforming to the first communication protocol and data units conforming to the second communication protocol, and to determine that such data units conform to the first communication protocol or to the second communication protocol, according to various embodiments.
In various embodiments, the MAC processor 28 and the PHY processor 29 of the client device 25-1 are configured to generate data units conforming to the first communication protocol. The transceiver(s) 30 is/are configured to transmit the generated data units via the antenna(s) 34. Similarly, the transceiver(s) 30 is/are configured to receive data units via the antenna(s) 34. In some embodiments, the MAC processor 28 and/or the PHY processor 29 are configured to process received data units conforming to the first communication protocol and having different data unit formats defined by the first communication protocol, and to determine that such data units conform to the various data unit formats of the first communication protocol, according to various embodiments. In some embodiments, he the MAC processor 28 and/or PHY processing unit 29 of the client device 25-1 are configured to process received data units conforming to the first communication protocol and data units conforming to the second communication protocol, and to determine that such data units conform to the first communication protocol or the second communication protocol, according to various embodiments.
FIG. 5 is a diagram of a prior art OFDM data unit 500 that the client station AP 14 is configured to transmit to the client station 25-4 via orthogonal frequency domain multiplexing (OFDM) modulation, according to an embodiment. In an embodiment, the client station 25-4 is also configured to transmit the data unit 500 to the AP 14. The data unit 500 conforms to the IEEE 802.11ac Standard and is designed for “Mixed field” situations. The data unit 500 occupies a 20 MHz bandwidth. In other embodiments or scenarios, a data unit similar to the data unit 500 occupies a different bandwidth, such as a 40 MHz, an 80 MHz, or a 160 MHz bandwidth. The data unit 500 includes a preamble having an L-STF 502, an L-LTF 504, an L-SIG 506, two first very high throughput signal fields (VHT-SIGAs) 508 including a first very high throughput signal field (VHT-SIGA1) 508-1 and a second very high throughput signal field (VHT-SIGA2) 508-2, a very high throughput short training field (VHT-STF) 510. M very high throughput long training fields (VHT-LTFs) 512, where M is an integer, and a second very high throughput signal field (VHT-SIG-B) 514. The data unit 500 also includes a data portion 516.
FIG. 6 is a diagram of an OFDM data unit 600 that the client station AP 14 is configured to transmit to the client station 25-1 via orthogonal frequency domain multiplexing (OFDM) modulation, according to an embodiment. In an embodiment, the client station 25-1 is also configured to transmit the data unit 600 to the AP 14. In an embodiment, the data unit 600 conforms to the first communication protocol and occupies a 20 MHz bandwidth. Data units that conform to the first communication protocol similar to the data unit 600 may occupy other suitable bandwidths such as 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc., for example, or other suitable bandwidths, in other embodiments. The data unit 600 is suitable for “mixed mode” situations, i.e., when the WLAN 10 includes a client station (e.g., the legacy client station 25-4) that conforms to a legacy communication protocol, but not the first communication protocol. The data unit 600 is utilized in other situations as well, in some embodiments.
In the embodiment of FIG. 6, the data unit 600 includes one of each of the L-STF 602, the L-LTF 604, the L-SIG 606, and the HE-SIGAs 608. In other embodiments in which an OFDM data unit similar to the data unit 600 occupies a cumulative bandwidth other than 20 MHz, each of the L-STF 602, the L-LTF 604, the L-SIG 606, the HE-SIGAs 608 is repeated over a corresponding number of 20 MHz-wide sub-bands of the whole bandwidth of the data unit, in an embodiment. For example, in an embodiment, the OFDM data unit occupies an 80 MHz bandwidth and, accordingly, includes four of each of the L-STF 602, the L-LTF 604, the L-SIG 606, and the HE-SIGAs 608 in four 20 MHz-wide sub-bands that cumulatively span the 80 MHz bandwidth, in an embodiment.
The co-existence, in a communication network, of multiple devices conforming to different communication protocols using different data unit formats, requires an ability within a receiver device to determine, in a received data unit, the communication protocol used for the received data unit. In addition, a single communication protocol can define multiple data unit formats corresponding to, for example, different operation modes, different transmission ranges, different throughputs, different power consumption levels, etc. Hence, it is often useful for a receiver to make a determination regarding the format of a received data unit so that the receiver can process the data unit according to the correct data unit format.
In some embodiments/scenarios, it is advantageous to distinguish amongst the multiple data unit formats early within a received data unit, such as during reception and/or processing of a PHY preamble. Early detection of the data unit format is useful, for example, when different data unit formats have different corresponding PHY preamble formats, at least in some embodiments.
Pilots, transmitted in the form of pilot sequences that are modulated over pilot subcarriers and typically used for phase and frequency tracking, and channel estimation purposes, are used for enabling distinction between different data unit formats, according to some embodiments.
FIG. 7 is a diagram of a prior art OFDM data unit 700 that the AP 14 is configured to transmit to one or more of the client stations 25 via orthogonal frequency domain multiplexing (OFDM) modulation, according to an embodiment. In an embodiment, one or more of the client stations 25 are also configured to transmit the OFDM data unit 700 to the AP 14. In an embodiment, the data unit 700 conforms to the IEEE 802.11n Standard and is designed for “Mixed field” situations. In another embodiment, the OFDM data unit 700 conforms to the IEEE 802.11ac Standard and is designed for “Mixed field” situations. In the embodiment of FIG. 7, the OFDM data unit 700 occupies a 20 MHz bandwidth. The OFDM data unit 700 includes 52 total subcarriers, comprising 48 data subcarriers and 4 pilot subcarriers, and the pilot subcarriers are located on subcarrier indices ±7, ±21. In an embodiment, the subcarriers are spaced 312.5 kHz apart. The pilot subcarriers modulate pilot sequences that are defined by a communication protocol (e.g., defined by the IEEE 802.11ac Standard). In some embodiments, PHY preamble fields L-SIG, HT-SIG, HT-LTFs, and a data portion (see e.g., FIG. 4) are transmitted using all of the data subcarriers of the OFDM data unit 700. In other embodiments, PHY preamble fields L-SIG, VHT-SIGAs, VHT-LTFs, and a data portion (see e.g., FIG. 5) are transmitted using all of the data subcarriers of the OFDM data unit 700.
In some embodiments, an n-th OFDM symbol of the OFDM data unit 700, e.g., starting from L-SIG, is given by:
r n ⁡ ( t ) = 1 N field tone ⁢ ∑ k = - N SD N SD ⁢ ( x n , k + p n ⁢ P k ) ⁢ exp ⁡ ( j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ k ⁢ ⁢ Δ F ⁡ ( t - T GI ) ) Equation ⁢ ⁢ 1
where, xn,k is a value of a mapped constellation point of the data unit for the n-th symbol at a k-th subcarrier tone, k is a subcarrier index, ±NSD are the minimum and maximum subcarrier indices, ΔF is a subcarrier bandwidth, pn is an n-th value of a bit sequence defined by a communication protocol, Pk is another sequence defined by the communication protocol, and TGI is a guard interval duration. Parameter pnPk sets a pilot value at the n-th symbol and k-th subcarrier tone. In some embodiments, Pk={1,1,1,−1} are pilot values at k=−21, −7, 7, and 21, and zero at other values of k. In some embodiments, pn is a cyclic extension of a 127-bit sequence.
In embodiments described herein, data unit formats (e.g., PHY data unit formats) are distinguished based on pilot sequences in OFDM symbols of a data unit. In various embodiments, one or more pilot sequences are selected from a plurality of pilot sequences based on a format of the data unit to be transmitted, wherein different pilot sequences in the plurality of pilot sequences correspond to different data unit formats (e.g., PHY data unit formats). In some embodiments, the one or more selected pilot sequences span multiple OFDM symbols of the data unit. In other embodiments, the one or more selected pilot sequences span a single OFDM symbol of the data unit. In some embodiments, a format of a received data unit is determined on the basis of an identified pilot sequence in the received data unit.
FIG. 8 is a diagram of an example data unit 800 that the AP 14 is configured to generate and transmit to the client station 25-1 via OFDM modulation, according to some embodiments. In some embodiments, the client station 25-1 is also configured to generate and transmit the data unit 800 to the AP 14. In an embodiment, the data unit 800 conforms to the first communication protocol and occupies a 20 MHz bandwidth. In other embodiments, the data unit 800 occupies another suitable bandwidth, such as 5 MHz, 10 MHz, 40 MHz, etc. The OFDM data unit 800 includes 52 total subcarriers, comprising 48 data subcarriers and 4 pilot subcarriers, and the pilot subcarriers are located on subcarrier indices ±7, ±21. In an embodiment, the subcarriers are spaced 312.5 kHz apart. The pilot subcarriers modulate pilot sequences. In some embodiments, different suitable numbers of one or both of i) total subcarriers, and/or ii) pilot subcarriers, are utilized. In some embodiments, pilot subcarriers are located at suitable subcarrier indices other than ±7, ±21, and/or a suitable subcarrier spacing other than 312.5 kHz is utilized.
The AP 14 or the client station 25-1 selects a pilot sequence based on the format of the data unit 800 that is to be transmitted, where different pilot sequences correspond to different data unit formats, according to some embodiments. The selected pilot sequence is included in the data unit 800 on pilot subcarriers. The AP 14 or the client station 25-1 selects the pilot sequence from a plurality of pilot sequences that correspond to a plurality of different data unit formats. In some embodiments, the selected pilot sequence is used for generating pilots on pilot subcarriers across multiple OFDM symbols 804 of the data unit 800.
In the illustrative embodiment of FIG. 8, some pilots (sometimes referred to herein as “new pilots”) are different as compared to the pilot tone sequence illustrated in FIG. 7. Thus, in an embodiment, a receiver is configured to recognize the pilot tone sequence illustrated in FIG. 8 as compared to the pilot tone sequence illustrated in FIG. 7, and based on the recognition, determine that the data unit 800 conforms to the first communication protocol, for example, rather than another communication protocol to which the data unit 700 of FIG. 7 conforms.
While the embodiment of FIG. 8 illustrates different pilots (as compared to the pilots illustrated in FIG. 7) on three OFDM symbols 804, in other embodiments, different pilots are on a different suitable number of OFDM symbols (e.g., one, two, four, five, etc.).
In FIG. 8, some pilots (sometimes referred to herein as “legacy pilots”) are the same as pilots illustrated in FIG. 7.
In some embodiments, the OFDM symbols 804 comprising the new pilots are included in the data unit 800 after an OFDM symbol 802 that includes legacy pilots. In some embodiments, an OFDM symbol 806 that follows the OFDM symbols 804 comprises legacy pilots. In some embodiments, the OFDM symbol 802 corresponds to L-SIG 606 (FIG. 6). In some embodiments, the OFDM symbols 804 correspond to HE-SIG fields 608 and HE-STF 610 (FIG. 6). In some embodiments, the OFDM symbol 806 corresponds to HE-LTF 612-1 (FIG. 6).
Referring now to FIGS. 1 and 8, in some embodiments, the AP 14 is configured to receive the data unit 800 from the client station 25-1. The AP 14 (e.g., the PHY processor 20) determines a pilot sequence that is modulated by pilot subcarriers of the received data unit 800. The AP 14 (e.g., the PHY processor 20) then identifies the pilot sequence from among a plurality of pilot sequences corresponding to a plurality of data unit formats. As merely an illustrative example, the AP 14 (e.g., the PHY processor 20) determines that that the pilot sequence corresponds to the sequence illustrated in FIG. 8 as compared to another one or more sequences, such as the sequence illustrated in FIG. 7. In some embodiments, the plurality of data unit formats include different data unit formats corresponding to different communication protocols and/or corresponding to different data unit formats of a single communication protocol. Following identification of the data unit format, the AP 14 (e.g., the PHY processor 20 and/or the MAC processor 18) processes the received data unit 800 according to the identified data unit format.
Similarly, in an embodiment, the client station 25-1 is configured to receive the data unit 800 from the AP 14 or from another client station 25. The client station 25-1 (e.g., the PHY processor 29) determines a pilot sequence that is modulated by pilot subcarriers of the received data unit 800. The client station 25-1 (e.g., the PHY processor 29) then identifies the pilot sequence from among a plurality of pilot sequences corresponding to a plurality of data unit formats. As merely an illustrative example, the AP client station 25-1 (e.g., the PHY processor 29) determines that that the pilot sequence corresponds to the sequence illustrated in FIG. 8 as compared to another one or more sequences, such as the sequence illustrated in FIG. 7. In some embodiments, the plurality of data unit formats include different data unit formats corresponding to different communication protocols and/or corresponding to different data unit formats of a single communication protocol (e.g., multiple data unit formats of the first communication protocol). Following identification of the data unit format, the client station 25-1 (e.g., the PHY processor 29 and/or the MAC processor 28) processes the received data unit 800 according to the identified data unit format.
FIG. 9 is a diagram of an example data unit 900 that the AP 14 and/or the client station 25-1 is configured to generate and transmit according to some embodiments. The data unit 900 is similar to the OFDM data unit 800 in some embodiments. The AP 14 or the client station 25-1 selects a pilot sequence based on the data unit format of the data unit 900 that is to be transmitted. The AP 14 or the client station 25-1 selects the pilot sequence from a plurality of pilot sequences that correspond to a plurality of data unit formats, in some embodiments. The selected pilot sequence is used for generating pilots that are transmitted on pilot subcarriers of one OFDM symbol 904 of the OFDM data unit 900.
In the illustrative embodiment of FIG. 9, some pilots (sometimes referred to herein as “new pilots”) are different as compared to the pilot tone sequence illustrated in FIG. 7. Thus, in an embodiment, a receiver is configured to recognize the pilot tone sequence illustrated in FIG. 9 as compared to the pilot tone sequence illustrated in FIG. 7, and based on the recognition, determine that the data unit 900 conforms to the first communication protocol, for example, rather than another communication protocol to which the data unit 700 of FIG. 7 conforms.
In the illustrative embodiment of FIG. 9, some pilots are different as compared to the pilot tone sequence illustrated in FIG. 8. Thus, in an embodiment, a receiver is configured to recognize the pilot tone sequence illustrated in FIG. 9 as compared to the pilot tone sequence illustrated in FIG. 8, and based on the recognition, determined that the data unit 900 is of a different format, for example, as compared to a data unit format of the data unit 800 of FIG. 8.
In some embodiments, the OFDM symbol 904 is included in the data unit 900 after an OFDM symbol 902 that includes legacy pilots. In some embodiments, an OFDM symbol 906 that follows the OFDM symbols 904 comprises legacy pilots. In some embodiments, the OFDM symbol 902 corresponds to L-SIG 606 (FIG. 6). In some embodiments, the OFDM symbol 904 corresponds to HE-SIGA1 608-1 (FIG. 6). In some embodiments, the OFDM symbol 906 corresponds to HE-SIGA1 608-2 (FIG. 6).
Referring now to FIGS. 1 and 9, in some embodiments, the AP 14 is configured to receive the data unit 900 from the client station 25-1. The AP 14 (e.g., the PHY processor 20) determines a pilot sequence that is modulated by pilot subcarriers of the received data unit 900. The AP 14 (e.g., the PHY processor 20) then identifies the pilot sequence from among a plurality of pilot sequences corresponding to a plurality of data unit formats. As merely an illustrative example, the AP 14 (e.g., the PHY processor 20) determines that that the pilot sequence corresponds to the sequence illustrated in FIG. 9 as compared to another one or more sequences, such as the sequence illustrated in FIG. 7 and/or the sequence illustrated in FIG. 8. In some embodiments, the plurality of data unit formats include different data unit formats corresponding to different communication protocols and/or corresponding to different data unit formats of a single communication protocol (e.g., multiple data unit formats of the first communication protocol). Following identification of the data unit format, the AP 14 (e.g., the PHY processor 20 and/or the MAC processor 18) processes the received data unit 900 according to the identified data unit format.
Similarly, in an embodiment, the client station 25-1 is configured to receive the data unit 900 from the AP 14 or from another client station 25. The client station 25-1 (e.g., the PHY processor 29) determines a pilot sequence that is modulated by pilot subcarriers of the received data unit 900. The client station 25-1 (e.g., the PHY processor 29) then identifies the pilot sequence from among a plurality of pilot sequences corresponding to a plurality of data unit formats. As merely an illustrative example, the AP client station 25-1 (e.g., the PHY processor 29) determines that that the pilot sequence corresponds to the sequence illustrated in FIG. 9 as compared to another one or more sequences, such as the sequence illustrated in FIG. 7 and/or the sequence illustrated in FIG. 8. In some embodiments, the plurality of data unit formats include different data unit formats corresponding to different communication protocols and/or corresponding to different data unit formats of a single communication protocol (e.g., different data unit formats of the first communication protocol). Following identification of the data unit format, the client station 25-1 (e.g., the PHY processor 29 and/or the MAC processor 28) processes the received data unit 900 according to the identified data unit format.
FIG. 10 is a diagram of OFDM data unit 1000 that the AP 14 and/or the client station 25-1 is configured to generate and transmit according to some embodiments. The OFDM data unit 1000 is similar to the OFDM data unit 800 in some embodiments. The AP 14 or the client station 25-1 selects a pilot sequence based on the format of the OFDM data unit 1000 to be transmitted. The AP 14 or the client station 25-1 selects a pilot sequence from a plurality of pilot sequences that correspond to a plurality of data unit formats. In some embodiments, the selected pilot sequence is used for generating pilots on pilot subcarriers across multiple OFDM symbols 1004 of the data unit 1000.
In the illustrative embodiment of FIG. 10, some pilots (sometimes referred to herein as “new pilots”) are different as compared to the pilot tone sequence illustrated in FIG. 7. Thus, in an embodiment, a receiver is configured to recognize the pilot tone sequence illustrated in FIG. 10 as compared to the pilot tone sequence illustrated in FIG. 7, and based on the recognition, determined that the data unit 1000 conforms to the first communication protocol, for example, rather than another communication protocol to which the data unit 700 of FIG. 7 conforms.
In the illustrative embodiment of FIG. 10, some pilots are different as compared to the pilot tone sequences illustrated in FIGS. 8 and 9. Thus, in an embodiment, a receiver is configured to recognize the pilot tone sequence illustrated in FIG. 10 as compared to the pilot tone sequences illustrated in FIGS. 8 and 9, and based on the recognition, determined that the data unit 1000 is of a different format, for example, as compared to a data unit formats of the data units 800 and 900 of FIGS. 8 and 9.
While the embodiment of FIG. 10 illustrates different pilots (as compared to the pilots illustrated in FIG. 7) on three OFDM symbols 1004, in other embodiments, different pilots are on a different suitable number of OFDM symbols (e.g., one, two, four, five, etc.).
In FIG. 10, some pilots (sometimes referred to herein as “legacy pilots”) are the same as pilots illustrated in FIG. 7.
In some embodiments, the OFDM symbols 1004 comprising the new pilots are included in the data unit 1000 after an OFDM symbol 1002 that includes legacy pilots. In some embodiments, an OFDM symbol 1006 that follows the OFDM symbols 1004 comprises legacy pilots. In some embodiments, the OFDM symbol 1002 corresponds to L-SIG 606 (FIG. 6). In some embodiments, the OFDM symbols 1004 corresponds to HE-SIG fields 608 and HE-STF 610 (FIG. 6). In some embodiments, the OFDM symbol 1006 corresponds to HE-LTF 612-1 (FIG. 6).
Referring now to FIGS. 1 and 10, in some embodiments, the AP 14 is configured to receive the data unit 1000 from the client station 25-1. The AP 14 (e.g., the PHY processor 20) determines a pilot sequence that is modulated by pilot subcarriers of the received data unit 1000. The AP 14 (e.g., the PHY processor 20) then identifies the pilot sequence from among a plurality of pilot sequences corresponding to a plurality of data unit formats. As merely an illustrative example, the AP 14 (e.g., the PHY processor 20) determines that that the pilot sequence corresponds to the sequence illustrated in FIG. 10 as compared to another one or more sequences, such as one or more of the sequences illustrated in FIGS. 7-9. In some embodiments, the plurality of data unit formats include different data unit formats corresponding to different communication protocols and/or corresponding to different data unit formats of a single communication protocol (e.g., multiple data unit formats of the first communication protocol). Following identification of the data unit format, the AP 14 (e.g., the PHY processor 20 and/or the MAC processor 18) processes the received data unit 1000 according to the identified data unit format.
Similarly, in an embodiment, the client station 25-1 is configured to receive the data unit 1000 from the AP 14 or from another client station 25. The client station 25-1 (e.g., the PHY processor 29) determines a pilot sequence that is modulated by pilot subcarriers of the received data unit 1000. The client station 25-1 (e.g., the PHY processor 29) then identifies the pilot sequence from among a plurality of pilot sequences corresponding to a plurality of data unit formats. As merely an illustrative example, the AP client station 25-1 (e.g., the PHY processor 29) determines that that the pilot sequence corresponds to the sequence illustrated in FIG. 10 as compared to another one or more sequences, such as one or more of the sequences illustrated in FIGS. 7-9. In some embodiments, the plurality of data unit formats include different data unit formats corresponding to different communication protocols and/or corresponding to different data unit formats of a single communication protocol (e.g., different data unit formats of the first communication protocol). Following identification of the data unit format, the client station 25-1 (e.g., the PHY processor 29 and/or the MAC processor 28) processes the received data unit 1000 according to the identified data unit format.
In some embodiments, an n-th symbol of an OFDM data unit starting from L-SIG is expressed as:
r n ⁡ ( t ) = 1 N field tone ⁢ ∑ k = - N SD N SD ⁢ ( x n , k + p n ⁢ c n , k ⁢ P k ) ⁢ exp ⁡ ( j ⁢ ⁢ 2 ⁢ ⁢ π ⁢ ⁢ k ⁢ ⁢ Δ F ⁡ ( t - T GI ) ) Equation ⁢ ⁢ 2
where cn,k is an n-th value of a sequence at the k-th subcarrier tone. Parameter pncn,kPk sets a pilot value of the pilot sequence at the n-th symbol and the k-th subcarrier tone, and the sequence cn,k is selected from a plurality of sequences on a data unit format of the data unit to be transmitted.
In one such embodiment according to Equation 2, the sequence varies for different OFDM symbols, but is identical for all pilot subcarrier tones in each OFDM symbol. In the embodiment where a total of 52 subcarriers are present, pilot subcarrier tones at subcarrier indices ±7, ±21 modulate a pilot sequence which is set by the selected sequence cn,k. In some embodiments, some values of the sequence cn,k correspond to a value of a pilot flipped in polarity as compared to other sequences cn,k and/or as compared to legacy pilots. In one illustrative embodiment, an n-th value of the sequence at a k-th subcarrier tone is defined by an equation:
c n , k = { 1 n ∈ { 1 } ⋃ Ω 1 - 1 n ∈ Ω 2 , for ⁢ ⁢ k = ± 7 , ± 21 Equation ⁢ ⁢ 3
where the OFDM symbol corresponding to n=1 corresponds to L-SIG 606 (FIG. 6), Ω1 is a first set of OFDM symbols in the data unit, and Ω2 is a second set of OFDM symbols in the data unit. In another embodiment, cn,k includes one or more elements that is/are complex valued. In another embodiment, cn,k is different for each symbol in Ω2.
In an embodiment according to Equation 2, multiple elements of cn,k for multiple pilots in a single OFDM symbol have different values. In another embodiment according to Equation 2, elements of the sequence cn,k corresponding pilots in an OFDM symbol are all different. In an embodiment where a total of 52 subcarriers are present, pilot subcarrier tones at subcarrier indices ±7, ±21 modulate pilot sequences which are set by a selected sequence. In one such embodiment, an n-th value of the sequence at a k-th subcarrier tone is defined by an equation:
c n , k = { [ 1 1 1 1 ] n ∈ { 1 } ⋃ Ω 1 [ s n , 1 s n , 2 s n , 3 s n , 4 ] n ∈ Ω 2 Equation ⁢ ⁢ 4
where parameters sn,k correspond to suitable values for distinguishing between different pilot tone sequences. In an embodiment, each symbol in Ω2 uses a same set of parameters sn,k. In another embodiment, multiple symbols in Ω2 use different sets of parameters sn,k. In another embodiment, each symbol in Ω2 uses a unique and different set of parameters sn,k. In an embodiment, parameters among the set of parameters sn,k are integers. In an embodiment, parameters among the set of parameters sn,k are real-valued numbers. In an embodiment, parameters among the set of parameters sn,k are complex valued numbers.
In some embodiments, a pilot sequence for a data unit is selected from among a plurality of pilot sequences, wherein the plurality of pilot sequences are in a look-up table stored in a memory of the AP 14 and/or the client station 25-1. In another embodiment, a pilot sequence is generated using a sequence which is selected from a plurality of sequences in a look-up table stored in a memory of the AP 14 and/or the client station 25-1. In an embodiment, a pilot sequence is generated using pncn,kPk as discussed above. In another embodiment, a pilot sequence is generated using selected parameters according to another suitable method. In an embodiment, a sequence corresponds to a parameter having a different format as compared to Equation 3 and Equation 4.
Following the selection of a pilot sequence, the AP 14 or the client station 25-1, generates a data unit to include the selected pilot sequence. The generated data unit is then transmitted.
Referring again to FIG. 8, in some embodiments, where an n-th OFDM symbol of a data unit corresponds to Equation 2, a pilot sequence in the received data unit 800 is defined by the parameter pncn,kPk, and identifying the pilot sequence includes identifying whether the pilot sequence in the received data unit 800 is in accordance with the parameter pncn,kPk. Similarly, referring again to FIGS. 9 and 10, in other embodiments, a pilot sequence in the data unit 900 or the data unit 1000 is defined by the parameter pncn,kPk, and identifying the pilot sequence includes identifying whether the pilot sequence in the received data unit 900/1000 is in accordance with the parameter pncn,kPk. In some embodiments, identifying a pilot sequence defined by a parameter pncn,kPk includes identifying the sequence cn,k. Parameter pncn,kPk can be used to determine a set of values (e.g., for multiple pilot tones at different values of k) of the sequence cn,k, for a given n.
In some embodiments, a sequence cn,k in the data unit 800, the data unit 900, or the data unit 1000 is defined by a specification such as Equation 3 or Equation 4 (or according to another equation or specification), and identifying the sequence cn,k includes identifying whether the sequence is corresponds to the specification. In other embodiments, a pilot sequence is identified from a sequence cn,k using suitable mathematical operations different from that defined in Equations 2-4.
In some embodiments, a pilot sequence for a received data unit (e.g., the data unit 800, the data unit 900, the data unit 1000, or another suitable data unit) is identified from among a plurality of pilot sequences, wherein indications of the plurality of pilot sequences are stored in a memory of a communication device that received the data unit (e.g., the AP 14, the client device 25-1, etc.). In some embodiments, a sequence cn,k is determined from a pilot sequence in the received data unit (e.g., the data unit 800, the data unit 900, the data unit 1000, or another suitable data unit), and the sequence cn,k is identified from a plurality of sequences cn,k stored in the memory of the communication device that receives the data unit.
Following identification of the pilot sequence in the received data unit, the communication device that received the data unit (e.g., heap 14, the client station 25-1, or another suitable communication device) determines, based on the identified pilot sequence, a format of the received data unit. Finally, the communication device that received the data unit processes the received data unit according to the determined format of the data unit.
While example embodiments were described above in the context of data units that occupy a 20 MHz bandwidth, in other embodiments or scenarios, the data unit occupies a different suitable bandwidth, such as a 1 MHz, 2 MHz, 5 MHz, 10 MHz, 40 MHz, 80 MHz, 160 MHz, 320 MHz, 640 MHz, etc., for example, or other suitable bandwidths, in other embodiments. In other embodiments, the data unit includes 114, or 242, or 484, or other suitable number of subcarriers, and the pilot subcarriers are located at other subcarrier indices such as ±11, ±25, ±53, or at ±11, ±39, ±75, ±103, or at ±25, ±53, ±89, ±117, ±139, ±167, ±203, ±231, or at other suitable subcarrier indices.
FIG. 11 is a flow diagram of an example method 1100 for generating and transmitting a data unit that includes a selected pilot sequence, according to an embodiment. In an embodiment, the method 1100 is implemented by a communication device in a WLAN, according to an embodiment. With reference to FIG. 1, the method 1100 is implemented by the network interface 27, in an embodiment. For example, in one such embodiment, the PHY processor 29 is configured to implement at least a portion of the method 1100. According to another embodiment, the MAC processing 28 is also configured to implement at least a part of the method 1100. With continued reference to FIG. 1, in yet another embodiment, the method 1100 is implemented by the network interface 16 (e.g., the PHY processor 20 and/or the MAC processor 18). In other embodiments, the method 1100 is implemented by other suitable network interfaces.
At block 1102, a communication device determines a format according to which a data unit is to be generated. In some embodiments, a format is according to a first communication protocol. In other embodiments, a format is according to one of a plurality of formats defined by the first communication protocol. In some embodiments, the data unit to be generated is a PHY data unit (e.g., a PHY protocol data unit (PPDU)).
At block 1104, the communication device, based on the determined format to be used for generating the data unit, selects a pilot sequence to be used for generating the data unit. In an embodiment, a pilot sequence is selected from a plurality of pilot sequences corresponding to a plurality of data unit formats. In some embodiments, where a pilot sequence is generated according to a parameter pncn,kPk, e.g., as defined in Equation 2 or another suitable parameter, a sequence cn,k (e.g., such as in Equation 3 or Equation 4, or another suitable sequence) is selected. In some embodiments, a pilot sequence and/or sequence cn,k is selected from a plurality of sequences stored in a memory of the communication device.
More generally, in some embodiments, the communication device, based on the determined format to be used for generating the data unit, selects a pattern of pilot signals that are to be included in the data unit. In an embodiment, a pattern is selected from a plurality of patterns corresponding to a plurality of data unit formats.
At block 1106, the communication device generates the data unit to include the selected pilot sequence. In an embodiment, generating the data unit includes generating a PHY data unit with the selected pilot sequence modulating pilot subcarriers in one or more OFDM symbols. In some embodiments, generating a pilot sequence includes generating the pilot signals using the parameter pncn,kPk. More generally, in some embodiments, the communication device generates the data unit to include the selected pattern of pilot signals.
At block 1108, the communication device transmits the data unit including the selected pilot sequence.
FIG. 12 is a flow diagram illustrating an example method 1200 for processing a received data unit, according to an embodiment. In an embodiment, the method 1200 is implemented by a communication device in a WLAN, according to an embodiment. With reference to FIG. 1, the method 1200 is implemented by the network interface 27, in an embodiment. For example, in one such embodiment, the PHY processor 29 is configured to implement at least a portion of the method 1200. According to another embodiment, the MAC processing 28 is also configured to implement at least a part of the method 1200. With continued reference to FIG. 1, in yet another embodiment, the method 1200 is implemented by the network interface 16 (e.g., the PHY processor 20 and/or the MAC processor 18). In other embodiments, the method 1200 is implemented by other suitable network interfaces.
At block 1202, a communication device receives a data unit via a communication channel. In some embodiments, the received data unit is a WLAN data unit.
At block 1204, the communication device determines a pilot sequence in the received data unit. In some embodiments, the determined pilot sequence is modulated by pilot subcarriers of in one or more OFDM symbols in the data unit.
At block 1206, the communication device identifies the pilot sequence of the received data unit from among a plurality of pilot sequences corresponding to a plurality of data unit formats. In some embodiments, at least some data unit formats in the plurality of data unit formats correspond to different communication protocols, and the identified pilot sequence indicates a communication protocol to which the data unit conforms. In some embodiments, at least some data unit formats in the plurality of data unit formats correspond to multiple data unit formats defined by a single communication protocol (e.g., the first communication protocol), and the identified pilot sequence indicates the data unit format, among the multiple data unit formats defined by the first communication protocol, to which the data unit conforms.
In some embodiments, identifying the pilot sequence includes identifying to which of multiple different parameters pncn,kPk the pilot sequence in the received data unit corresponds. In some embodiments, identifying to which of multiple different parameters pncn,kPk the pilot sequence in the received data unit corresponds includes identifying to which of multiple different sequences cn,k the pilot sequence in the received data unit corresponds. In some embodiments, the sequence cn,k corresponds to Equation 3 or Equation 4 (or to another suitable specification).
More generally, in some embodiments, the communication device determines a pattern of pilot signals in the data unit at block 1204, and identifies the determined pattern from among a plurality of pilot signal patterns corresponding to a plurality of data unit formats at block 1206.
At block 1208, the communication device determines, based on the identified pilot sequence, a format of the received data unit. More generally, in some embodiments, the communication device determines, based on the identified pattern of pilot signals, a format of the data unit.
At block 1210, the communication device, processes the received data unit according to the determined format of the received data unit. For example, in some embodiments, the different formats correspond to different PHY preamble formats having one or more of i) different fields, ii) different lengths of fields, iii) fields with different subfields, iv) different modulations of one or more fields, etc. Thus, in some embodiments, block 1210 includes processing the PHY preamble of the received data unit according to one or more of i) one or more fields specified by the determined format (e.g., at least some of the other formats do not include the one or more fields), ii) length(s) of one or more fields specified by the determined format (e.g., at least some of the other formats specified the field(s) to have different length(s)), iii) subfields of a field specified by the determined format (e.g., at least some of the other formats do not include the subfields and/or include other subfields that are omitted from the specified format), iv) a particular modulation or particular modulations of one or more fields (e.g., at least some of the other formats specify one or more fields to have modulation(s) different than those specified by the determined format), etc.
In some embodiments, techniques such as disclosed herein are combined with one or more techniques disclosed in U.S. patent application Ser. No. 15/017,385, filed on Feb. 5, 2016, entitled “Physical Layer Frame Format for WLAN,” which is hereby incorporated by reference herein in its entirety. For example, U.S. Provisional Patent Application No. 62/218,309, which is incorporated herein by reference, discloses various embodiments in which multiple techniques for indicating a format of a data unit are combined so that a receiver of the data unit can determine the format of the data unit using one or more techniques.
1. A method for transmitting a data unit comprising a plurality of orthogonal frequency division multiplexing (OFDM) symbols, the method comprising:
determining, at a communication device, a data unit format according to which a data unit is to be generated, the data unit format selected from a plurality of data unit formats;
selecting, at the communication device, a pilot sequence to be used for generating the data unit, wherein the pilot sequence is selected from a plurality of pilot sequences corresponding to the plurality of data unit formats, the pilot sequence is selected based on the determined data unit format, selecting the pilot sequence includes selecting a parameter cn,k based on the data unit format, cn,k is a sequence for an n-th OFDM symbol, and k is an OFDM subcarrier index;
generating, at the communication device, the data unit to include the selected pilot sequence modulated on one or more pilot subcarriers of one or more OFDM symbols of the plurality of OFDM symbols, wherein generating the data unit to include the selected pilot sequence comprises: generating one or more OFDM symbols of the plurality of OFDM symbols according to the sequence cn,k, and generating the data unit to include the selected pilot sequence, modulated on one or more pilot subcarriers, in one or more OFDM symbols corresponding to one or more fields of a physical layer (PHY) preamble that are after a legacy signal field in the PHY preamble and before a training field in the PHY preamble; and transmitting, by the communication device, the data unit including the selected pilot sequence modulated on the one or more pilot subcarriers, wherein the selected pilot sequence modulated on the one or more pilot subcarriers signals to a receiving device the data unit format of the data unit.
2. The method of claim 1, wherein at least some of the plurality of data unit formats correspond to different communication protocols.
3. The method of claim 1, wherein at least some of the plurality of data unit formats correspond to different formats defined by a single communication protocol.
4. The method of claim 1, wherein generating the data unit includes generating the data unit to include the selected pilot sequence across multiple OFDM symbols in the plurality of OFDM symbols of the data unit.
5. The method of claim 1, wherein generating the data unit includes generating the data unit to include the selected pilot sequence in one OFDM symbol in the plurality of OFDM symbols of the data unit.
6. The method of claim 1, wherein generating the data unit to include the pilot sequence includes generating the one or more OFDM symbols with pilot signals, modulated on the one or more pilot subcarriers, having flipped polarities.
a network interface device having one or more integrated circuits (ICs) configured to: determine a data unit format according to which a data unit is to be generated, the data unit format selected from a plurality of data unit formats; select a pilot sequence to be used for generating the data unit, wherein the pilot sequence is selected from a plurality of pilot sequences corresponding to the plurality of data unit formats, the pilot sequence is selected based on the determined data unit format, selecting the pilot sequence includes selecting a parameter cn,k, cn,k is a sequence for an n-th OFDM symbol, and k is an OFDM subcarrier index; and
wherein the one or more ICs are further configured to: generate the data unit to include the selected pilot sequence modulated on one or more pilot subcarriers of one or more orthogonal frequency division multiplexing (OFDM) symbols among a plurality of OFDM symbols of the data unit, wherein generating the data unit to include the selected pilot sequence comprises: generating one or more OFDM symbols of the plurality of OFDM symbols according to the sequence cn,k, and generating the data unit to include the selected pilot sequence, modulated on the one or more pilot subcarriers, in one or more fields of a physical layer (PHY) preamble that are after a legacy signal field in the PHY preamble and before a training field in the PHY preamble; and transmit the data unit including the selected pilot sequence modulated on the one or more pilot subcarriers, wherein the selected pilot sequence modulated on the one or more pilot subcarriers signals to a receiving device the data unit format of the data unit.
8. The apparatus of claim 7, wherein at least some of the plurality of data unit formats correspond to different communication protocols.
9. The apparatus of claim 7, wherein at least some of the plurality of data unit formats correspond to different formats defined by a single communication protocol.
10. The apparatus of claim 7, wherein the one or more ICs are configured to generate the data unit to include the selected pilot sequence across multiple OFDM symbols in the plurality of OFDM symbols of the data unit.
11. The apparatus of claim 7, wherein the one or more ICs are configured to generate the data unit to include the selected pilot sequence in one OFDM symbol in the plurality of OFDM symbols of the data unit.
12. The apparatus of claim 7, wherein the one or more ICs are configured to generate one or more OFDM symbols with pilot signals, modulated on the one or more pilot subcarriers, having flipped polarities.
receiving, at a communication device, a data unit via a communication channel, the data unit comprising a plurality of orthogonal frequency division multiplexing (OFDM) symbols;
determining, at the communication device, a pilot sequence modulated on one or more pilot subcarriers of one or more OFDM symbols of the plurality of OFDM symbols in the received data unit, wherein the pilot sequence is in one or more fields of a physical layer (PHY) preamble of the data unit, and wherein the one or more fields are after a legacy signal field in the PHY preamble and before a training field in the PHY preamble;
identifying, at the communication device, the pilot sequence, modulated on the one or more pilot subcarriers, in the received data unit from a plurality of pilot sequences corresponding to a plurality of data unit formats, wherein identifying the pilot sequence comprises identifying a sequence cn,k, wherein n is an OFDM symbol index and k is an OFDM subcarrier index;
determining, at the communication device, a data unit format of the received data unit corresponding to the identified pilot sequence modulated on the one or more pilot subcarriers; and
processing, at the communication device, the received data unit according to the determined data unit format.
14. The method of claim 13, wherein at least some of the plurality of data unit formats correspond to different communication protocols.
15. The method of claim 13, wherein at least some of the plurality of data unit formats correspond to different formats defined by a single communication protocol.
16. The method of claim 13, wherein identifying the pilot sequence in the received data unit includes identifying one or more OFDM symbols in the plurality of OFDM symbols of the received data unit with pilot signals, modulated on the one or more pilot subcarriers, that have flipped polarities.
a network interface device having one or more integrated circuits (ICs) configured to: receive a data unit via a communication channel, the data unit comprising a plurality of orthogonal frequency division multiplexing (OFDM) symbols, determine a pilot sequence modulated on one or more pilot subcarriers of one or more OFDM symbols of the plurality of OFDM symbols in the received data unit, wherein the pilot sequence is in one or more fields of a physical layer (PHY) preamble of the data unit, and wherein the one or more fields are after a legacy signal field in the PHY preamble and before a training field in the PHY preamble, identify the pilot sequence, modulated on the one or more pilot subcarriers, in the received data unit from a plurality of pilot sequences corresponding to a plurality of data unit formats, wherein identifying the pilot sequence comprises identifying a sequence cn,k, wherein n is an OFDM symbol index and k is an OFDM subcarrier index, determine a data unit format of the received data unit corresponding to the identified pilot sequence modulated on the one or more pilot subcarriers, and process the received data unit according to the determined data unit format.
18. The apparatus of claim 17, wherein at least some of the plurality of data unit formats correspond to different communication protocols.
19. The apparatus of claim 17, wherein at least some of the plurality of data unit formats correspond to different formats defined by a single communication protocol.
20. The apparatus of claim 17, wherein the one or more ICs are configured to identify one or more OFDM symbols in the plurality of OFDM symbols of the received data unit with pilot signals, modulated on the one or more pilot subcarriers, that have flipped polarities.
6553534 April 22, 2003 Yonge, III et al.
6856590 February 15, 2005 Okada et al.
7577210 August 18, 2009 Lee
7599332 October 6, 2009 van Zelst et al.
7889707 February 15, 2011 Niu et al.
7904519 March 8, 2011 Czotscher et al.
7961593 June 14, 2011 Porat et al.
8155138 April 10, 2012 van Nee
8310981 November 13, 2012 Damnjanovic et al.
8339978 December 25, 2012 Sawai et al.
8369301 February 5, 2013 Cai
8526351 September 3, 2013 Fischer et al.
8599804 December 3, 2013 Erceg et al.
8718021 May 6, 2014 Yu et al.
8724720 May 13, 2014 Srinivasa et al.
8737189 May 27, 2014 Hansen
8867653 October 21, 2014 Zhang et al.
8873680 October 28, 2014 Zhang
8885740 November 11, 2014 Zhang et al.
8948283 February 3, 2015 Zhang
8953696 February 10, 2015 Stoye
8982889 March 17, 2015 Zhang
9131528 September 8, 2015 Zhang et al.
9209837 December 8, 2015 Cheong et al.
9258178 February 9, 2016 Zhang
9350583 May 24, 2016 Zhang
20030056043 March 20, 2003 Kostadinov
20080299962 December 4, 2008 Kasher
20090086699 April 2, 2009 Niu et al.
20100034323 February 11, 2010 Stoye
20100103920 April 29, 2010 Damnjanovic et al.
20110110348 May 12, 2011 Lee et al.
20110271169 November 3, 2011 Pi
20120294268 November 22, 2012 Lee et al.
20120294392 November 22, 2012 Zhang
20130266083 October 10, 2013 Baik et al.
20150071372 March 12, 2015 Zhang
20150117433 April 30, 2015 Zhang et al.
20160156750 June 2, 2016 Zhang et al.
20170288748 October 5, 2017 Lou et al.
WO-2009/052420 April 2009 WO
WO-2009/059229 May 2009 WO
WO-2012/106635 August 2012 WO
IEEE P802.15.4m/D3, May 2013 IEEE Standard for Local metropolitan area networks—“Part 15.4: Low Rate Wireless Personal Area Networks (LR-WPANs)”, Amendment 6: TV White Space Between 54 MHz and 862 MHz Physical Layer, Excerpt, 2 pages (May 2013).
U.S. Appl. No. 15/265,614, Sun et al., “Physical Layer Frame Format for WLAN,” filed Sep. 14, 2016.
U.S. Appl. No. 15/180,801, Sun et al., “Signaling PHY Preamble Formats,” filed Jun. 13, 2016.
IEEE Std 802.11ad ™/D9.0 “Draft Standard for Information technology—Telecommunications and information Exchange Between Systems—Local and Metropolitan Area Networks Specific Requirements” Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 3: Enhancements for Very High Throughput in the 60 GHz Band The Institute of Electrical and Electronics Engineers, Inc., (Jul. 2012).
IEEE Std 802.11af/D1.05 “Draft Standard for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks-Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Amendment 4: TV White Spaces Operation,” The Institute of Electrical and Electronics Engineers, Inc., pp. 1-123 (Nov. 2011).
IEEE Std P802.11ad/D5.0 “Draft Standard for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks-Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Amendment 3: Enhancements for Very High Throughput in the 60 GHz Band,” The Institute of Electrical and Electronics Engineers, Inc., pp. 1-601 (Sep. 2011).
Harada, “Project: IEEE P802.15 Working Group for Wireless Personal Area Network (WPANs),” IEEE 802.15/07/0693-003c (May 2007).
Park, “Proposed Specification Framework for TGah”, The Institute of Electrical and Electronics Engineers, doc. No. IEEE 802.11--yy/xxxxr05, (Jan. 2012).
Park, “Proposed Specification Framework for TGah”, The Institute of Electrical and Electronics Engineers, doc. No. IEEE 802.11-11/1137r11, pp. 1-36 (Sep. 2012).
Perahia et al., “Gigabit Wireless LANs: an overview of IEEE 802.11 ac and 80211 ad,” ACM SIGMOBILE Mobile Computing and Communications Review, vo. 15, No. 3, pp. 23-33 (Jul. 2011).
Shi et al., “Phase Tracking During VHT-LTF,” Doc. No. IEEE 802.11-10/0771r0, The Institute of Electrical and Electronics Engineers, Inc., pp. 1-19 (Jul. 2010).
Stacey et al., “IEEE P802.11, Wireless LANs, Proposed TGac Draft Amendment,” Institute of Electrical and Electronics Engineers, doc. No. IEEE 802.Nov. 10, 1361 r3 (Jan. 2011 ).
Stacey et al., “Specification Framework for TGac,” document No. IEEE 802.11-09/0992r20, Institute tor Electrical and Electronics Engineers, pp. 1-49, Jan. 18, 2011.
Syafei et al., “Design of 1.2 Gbps MIMO WLAN System for 4K Digital Cinema Transmission,” IEEE 20th Int'l Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC 2009), The Institute of Electrical and Electronics Engineers, pp. 207-11 (2009).
van Nee et al., “The 802.11 n MIMO-OFDM Standard for Wireless LAN and Beyond,” Wireless Personal Communications, vol. 37, pp. 445-453 (Jun. 2006).
van Zelst et al., “Pilot Sequence for VHT-DATA,” Doc. No. IEEE 802.11-10/0811r1, The Institute of Electrical and Electronics Engineers, Inc., pp. 1-10 (Jul. 2010).
Vermani et al., “Spec Framework Text for PHY Numerology,” The Institute of Electrical and Electronics Engineers, doc. No. IEEE 802.11-11/13111.0, pp. 1-5 (Sep. 2011).
Vermani et al., “Preamble Format for 1 MHz,” The Institute of Electrical and Electronics Engineers, doc. No. IEEE 802.11-11/1482r2, pp. 1-30 (Nov. 2011).
Yu et al., “Coverage extension for IEEE802.11ah,” The Institute of Electrical and Electronics Engineers, doc. No. IEEE 802.11-11/0035r1 , pp. 1-10 (Jan. 2011).
Zhang et al., “1 MHz Waveform in Wider BW ”, The Institute of Electrical and Electronics Engineers, doc. No. IEEE 802.11-12/0309r1, pp. 1-10 (Mar. 2012).
Zhang Zhao-Yang: “A Novel AFDM Transmission Scheme with Length-Adaptive Cyclic Prefix,” Journal of Zhejiang University. Science, Zhejiant University Press, Hangzhou, CN vol. 5, No. 11, pp. 1336-1342 (Jul. 7, 2003).
Chun et al., “Legacy Support on HEW frame structure,” doc: IEEE 11-13/1057r0, The Institute of Electrical and Electronics Engineers, Inc., pp. 1-8 (Sep. 2013).
Seok et al., “HEW PPDU Format for Supporting MIMO-OFDMA,” IEEE 802.11-14/1210r0, 16 pages, (Sep. 14, 2014).
IEEE Std 802.11ac/D7.0 “Draft Standard for Information Technology—Telecommunications and information exchange between systems—Local and metropolitan area networks-Specific requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications: Amendment 4: Enhancements for Very High Throughput for Operation in Bands below 6 GHz,” The Institute of Electrical and Electronics Engineers, Inc., pp. 1-456 (Sep. 2013).
IEEE P802.11ax™/D0.1, “Draft Standard for Information technology—Telecommunications and information exchange between systems Local and metropolitan area networks—Specific Requirements, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications, Amendment 6: Enhancements for high efficiency in frequency bands between 1 GHz and 6 GHz,” The Institute of Electrical and Electronics Engineers, Inc., 221 pages (Mar. 2016).
IEEE Std 80211™ 2012 (Revision of IEEE Std 802.11-2007) IEEE Standard for Information technology—Telecommunications and information exchange between systems—Local and metropolitan area networks—Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, The Institute of Electrical and Electronics Engineers, Inc., pp. 1-2695 (Mar. 29, 2012).
Office Action in U.S. Appl. No. 15/265,614, dated Mar. 12, 2018 (30 pages).
Office Action in U.S. Appl. No. 15/265,614, dated Sep. 21, 2018 (26 pages).
Patent number: 10181966
Inventors: Yakun Sun (Sunnyvale, CA), Hongyuan Zhang (Fremont, CA)
Application Number: 15/143,075
International Classification: H04L 25/02 (20060101); H04L 5/00 (20060101); H04W 84/12 (20090101);