Coexistence of OFDM and on-off keying (OOK) signals in WLAN

A wireless transmit/receive unit (WTRU) or access point (AP) may generate a protocol data unit (PDU) of a first 802.11 protocol and a preamble and data of a second 802.11 protocol. The preamble and data of the second 802.11 protocol may be arranged on resources of the PDU of the first 802.11 protocol with shaping sequences for concurrent transmission.

BACKGROUND

Fixed or low mobility wireless communication for local area networks (LANs) utilize technologies such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.11ax, or generally 802.11x. These technologies relate to medium access control (MAC) and physical layer (PHY) specifications for creating wireless LANs (WLANs). With the growth of WLANs, it may be desirable to transmit signals in the same transmission for a number of types of WLAN interfaces to achieve desired performance and spectral efficiency. Collectively, these technologies are often referred to as WiFi.

SUMMARY

Transmitting or receiving concurrent 802.11 data or control in the same transmission is described. An access point (AP) or station (STA) may transmit or receive a multiplexed signal including 802.11 data or control protocol data units (PDUs). The AP or STA may multiplex the 802.11 data or control within one orthogonal frequency division multiplexing (OFDM) symbol length. The AP or STA may include a cyclic prefix of varying length in the transmission.

DETAILED DESCRIPTION

In an embodiment, the base station114aand the WTRUs102a,102b,102cmay implement multiple radio access technologies. For example, the base station114aand the WTRUs102a,102b,102cmay implement LTE radio access and NR radio access together, for instance using dual connectivity (DC) principles. Thus, the air interface utilized by WTRUs102a,102b,102cmay be characterized by multiple types of radio access technologies and/or communications sent to/from multiple types of base stations (e.g., an eNB and a gNB).

The RAN104may be in communication with the CN106, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs102a,102b,102c,102d. The data may have varying quality of service (QoS) requirements, such as differing throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, and the like. The CN106may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high-level security functions, such as user authentication. Although not shown inFIG. 1A, it will be appreciated that the RAN104and/or the CN106may be in direct or indirect communication with other RANs that employ the same RAT as the RAN104or a different RAT. For example, in addition to being connected to the RAN104, which may be utilizing a NR radio technology, the CN106may also be in communication with another RAN (not shown) employing a GSM, UMTS, CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.

In representative embodiments, the other networks112may be a WLAN.

The WTRUs102a,102b,102cmay communicate with gNBs180a,180b,180cusing communications associated with a scalable numerology. For example, the OFDM symbol spacing and/or OFDM subcarrier spacing (SCS) may vary for different communications, different cells, and/or different portions of the wireless communication spectrum. The WTRUs102a,102b,102cmay communicate with gNBs180a,180b,180cusing subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing varying number of OFDM symbols and/or lasting varying lengths of absolute time).

The CN106may facilitate communications with other networks. For example, the CN106may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the CN106and the PSTN108. In addition, the CN106may provide the WTRUs102a,102b,102cwith access to the other networks112, which may include other wired and/or wireless networks that are owned and/or operated by other service providers. In one embodiment, the WTRUs102a,102b,102cmay be connected to a local DN185a,185bthrough the UPF184a,184bvia the N3 interface to the UPF184a,184band an N6 interface between the UPF184a,184band the DN185a,185b.

Examples are given herein for communicating two different formats or types of 802.11 information, data, or control substantially concurrently or concurrently by WTRU, AP, STA, or the like. Concurrent transmission may increase utilization or efficiency of spectrum or resources. Although 802.11 is used in the examples described herein, concurrent transmission or multiplexing of different radio access technologies may similarly be adapted for the examples, techniques, or operations given herein. In NR, LTE, LTE-A, LTE-pro, or the like, OFDMA or discrete Fourier transform (DFT)-spread OFDM transmissions may multiplex coded wake-up (WU) signals, such as Manchester-coded on-off keying (OOK) signals, and data signals in the frequency domain. The WU signal may be transmitted over several resource blocks and the corresponding signal in the time domain may be coded OOK symbols, or pulse position modulation. Since the coded OOK symbols may be generated through several resources block, the contamination or interference on the adjacent subcarriers may be avoided, and orthogonality between WU signals and the data symbols may be maintained.

For concurrent 802.11 transmissions, a WLAN in infrastructure BSS mode may have an AP for the BSS and one or more stations STAs associated with the AP. A STA or AP may comprise a device embodied in hardware similar to that of a WTRU as described herein. The AP may have access or interface to a DS or another type of wired/wireless network that may carry traffic in and out of the BSS. Traffic for STAs that originates from outside the BSS may arrive through the AP and be delivered to the STAs. Traffic originating from STAs to destinations outside the BSS may be sent to the AP to be delivered to respective destinations. Traffic between STAs within the BSS may also be sent through the AP where the source STA sends traffic to the AP and the AP delivers the traffic to the destination STA. Such traffic between STAs within a BSS may also be configured for peer-to-peer traffic. Peer-to-peer traffic may also be sent directly between the source and destination STAs with a DLS using an 802.11e DLS or an 802.11z TDLS. A WLAN using IBSS mode may have no AP, and/or STAs, communicating directly with each other, such as in an ad-hoc communication mode.

To improve spectral efficiency, 802.11ac may be configured to utilize downlink Multi-User MIMO (MU-MIMO) transmission to multiple STAs in a same symbol's time frame such as during a downlink OFDM symbol. 802.11ah may also use downlink MU-MIMO, and as in 802.11ac, use the same symbol timing to multiple STA's. These transmissions may occur with minimal interference between multiple STA's. To further mitigate any interference, STA's utilizing MU-MIMO transmission with the AP may be configured to use the same channel or band, which may limit the operating bandwidth to the smallest channel bandwidth that is supported by the STA's included in the MU-MIMO communication with the AP.

In some configurations, 802.11ax may utilize OFDM for data in physical layer convergence procedure (PLOP) protocol data units (PPDUs) with a discrete Fourier transform (DFT) period of 12.8 μs, a SCS of 78.125 kHz, and/or 20 MHz bandwidth. 802.11ax may also utilize OFDMA technology that allows multiple users sharing available channels. The smallest bandwidth that each user may occupy in a channel may be a resource unit (RU), which may include 26, 52, 106, 242, 484, 996 or 2×996 tones. Distribution of RUs in a channel may be based on channel bandwidth.

FIG. 4is an example of coexistence of 802.11ax and 802.11ba. 802.11ba devices may utilize a wake-up radio (WUR) and may be configured to meet certain range, capability, coexistence, power consumption, latency, or the like metrics. 802.11ba devices may also use OOK modulation for a payload portion of a WU frame or packet. The OOK waveform of the WU frame or packet may be generated by populating a certain number of 802.11 OFDM subcarriers.

For range, the 802.11ba WUR may be a companion radio to the primary connectivity radio, such as an 802.11ax radio or device, that meets similar range metrics as the primary connectivity radio. WU frames may carry control information that may trigger a transition of the primary connectivity radio out of sleep, idle, or the like modes or states. For coexistence, WUR devices may coexist with legacy IEEE 802.11 devices in the same band. For power consumption, WUR devices may have a low target active receiver power consumption. For instance, less than one milliwatt (mW) may be desired for low power, battery operated, or wirelessly powered devices such as in IoT or MTC applications in healthcare, smart homes, sensors, industrial sensors, wearables, warehousing, fulfilment centers, user data and sensor coexistence, or the like.

For latency, power efficient configurations may be utilized for low power, battery operated, or wirelessly powered devices while maintaining low latency. For example, an OFDM active receiver that consumes tens to hundreds of mWs may reduce power consumption by utilizing power save modes. The longer devices remain in a power save mode, sleep state, or the like, the lower power may be consumed but at an increased latency of data reception.

In 802.11ax, an OFDM symbol duration may be 12.8 μs and cyclic prefix (CP) sizes of 0.8, 1.6, and, 3.2 μs may be utilized. In 802.11ba, an OOK symbol duration may be shorter than 12.8 μs, such as 3.2 μs, to be compatible with 802.11n or 802.11ac numerology. In this configuration, the numerologies for 802.11ba and 802.11ax may be incompatible. However, an 802.11ba numerology configured to account for the 802.11ax numerology may provide compatibility and operate with different CP sizes.

In addition, when 802.11ax is configured with OFDMA, data symbols for different STAs may be multiplexed in frequency for one OFDM symbol duration. InFIG. 4, an 802.11ax PPDU for a T1μs OOK symbol transmission by 802.11ax component404and an 802.11ba PPDU for an n×T1μs OFDM/A symbol transmission by component 802.11ax component402of STA400may be transmitted simultaneously or concurrently. Due to lack of orthogonality408, interference414may occur between STAs410and412receiving PPDUs from antenna406in different RUs. In this example, T1μs OOK symbol416may have CP418and T1μs OFDMA symbol420may have CP422. It is desirable to have symbol orthogonality or quasi-orthogonality between symbols424.

Communicating or multiplexing two different formats or types of 802.11 information, data, or control substantially concurrently or concurrently is given herein. Although 802.11 is used for examples, concurrent transmission or multiplexing of different radio access technologies may similarly be adapted for the techniques or operations given herein. In certain configurations, 802.11ba information, data, or control may be transmitted concurrently with 802.11ax. In such a transmission or communication, DFT-based shaping sequences for 802.11ba signals to generate multiple shaped symbols may be utilized. Other configurations such as variable 802.11ax symbol durations with 802.11ba symbols, CPs, preamble padding, blank-symbol insertion, edge transmission, or the like may also be utilized.

An 802.11ba transmission may be configured as part of an 802.11ax HE-MU PPDU transmission. As an example, an 802.11ax signal may be transmitted using OFDMA and the 802.11ba PPDU may be generated by using one or multiple RUs in the 802.11ax signal. To avoid interference between 802.11ax and 802.11ba portions, the 802.11ba signal may be generated in a manner that ensures unused RUs within the 802.11ax transmission are utilized.

FIG. 5Ais an example of an HE MU PPDU format for 802.11ax. In500, the HE MU PPDU may include a L-STF, L-LTF, L-SIG field, RL-SIG field, HE-SIG-A field, HE-SIG-B field, HE-STF, one or more HE-LTF, data, and a PE field.FIG. 5Bis an example of an 802.11ax HE MU PPDU format transmitted with 802.11ba after an HE-STF in the HE-preamble. In520, an 802.11ax HE MU PPDU may include an 802.11ba WU signal522concurrently with a L-STF, L-LTF, L-SIG field, RL-SIG field, HE-SIG-A field, HE-SIG-B field, HE-STF, one or more HE-LTF, data, and PE.

FIG. 5Cis an example of 802.11ax and 802.11ba coexistence with transmission after the HE-LTF in the HE-preamble. In this configuration, the variable overhead of one or more HE-LTF symbols, which may be precoded or allocated to a specific device, may be reduced. Frame or packet540may include a legacy preamble, 11ax preamble, and 11ax data on 11ax RUs concurrently with 11ba preamble and information542. In certain configurations herein, CP size or OFDM symbol duration may vary in the HE-LTF. In addition, for compatible transmission or multiplexing of 802.11ax and 802.11ba information, data, or control 4× HE-LTF may be utilized when WUR transmission is desired or a 3.2 μs CP duration may be utilized for WUR transmission during the 802.11ax preamble transmission.

FIG. 5Dis another example of an 802.11ax HE MU PPDU format transmitted with 802.11ba after the HE-preamble. As opposed to520, in560the 802.11ba WU signal or packet, that may partially start at or overlap with the WUR preamble, may start after the entire HE-preamble. In560, the preamble may end at the last HE-LTF. The configuration in560may allow an 802.11ax receiver to read the HE-SIG-B field and identify resources allocated for the STA.

FIG. 5Eis an example of 802.11ax and 802.11ba coexistence with transmission after the HE-preamble. As opposed to540, 11ba transmission within 11ax RUs that may include preamble and data582configured in580. InFIGS. 5D and 5Ethe WUR signal may be sent for the duration of the 802.11ax signal. Also, in this configuration to ensure frequency domain orthogonality or quasi-orthogonality between bands while substantially maintaining existing 802.11ba receiver architecture, a bandpass filter may be utilized before WUR envelope detection. The number of RUs allocated to the WUR signal may depend on bandpass filter sensitivity. For instance, a signal may include an additional 26 tone RUs allocated as guard bands for filters that have lower sensitivity. Moreover, this configuration may utilize a setup procedure between the transmitter and WUR receiver to identify the number of RUs to be allocated and the bandwidth of the corresponding WUR signal.

When the WUR signal is generated as a CP OFDM signal to ensure orthogonality or quasi-orthogonality with the 802.11ax data on other RUs, a band-pass filter may be unnecessary. Additionally, within each OFDM symbol, it may be desirable for the WUR signal to have a CP to ensure that the signal may be transformed to the frequency domain using simple inverse DFT (IDFT) or FFT processing by 802.11ax receivers. However, this configuration may reduce the useful duration of the WUR signal and may need signaling of guard intervals, such as G1 or G2, based on the size of the OFDMA symbol.

To reduce the effect of the WUR signal on the processing of 802.11ax signals, the WUR signal may be blanked or not transmitted if it falls within a time duration of a CP. For transmission without guard intervals or periods within an OFDM symbol, the length of the OOK signals may be modified such that an integer number of signals fit within an OFDM symbol duration.

FIG. 6is an example of an 802.11ba PDU for transmission on 802.11 ax RUs600. As explained herein, the configuration in600may provide frequency orthogonality or quasi-orthogonality of the 802.11ba and 802.11ax signals. In600, a frame or packet may include a legacy preamble and 802.11ax preamble602and an 802.11ax portion604and 802.11ba portion606in preamble608. Also, in600an 802.11ba PPDU may be transmitted during the payload duration of 802.11ax.

During an 802.11ba WUR configuration or setup, an STA may receive configuration information from the AP that may include setup for WUR in non-802.11ax coexistence mode, setup for WUR in 802.11ax coexistence mode, or STA specific preamble sequences and resources to scan for a sequence. For example, the sequence may be [1 0 1 0, 0 1 0 0, 1 0 1 1, 1 0 1 1, 0 0 0 1, 0 1 1 1, 0 0 1 1, 1 0 0 0], or the 2's complement of this sequence. The repetition of this sequence may indicate different data rates for WUR or other PHY modes. In the 802.11ax coexistence mode the WUR RU allocation for scanning may coincide with the resources allocated for the non-coexistence mode. A WUR device or receiver may be configured to scan more than one resource or scan a specific band or RU continuously for its WUR signal. In addition, a WUR may scan multiple pre-set bands to identify possible WU signals from the AP. A WU signal, which may include the WU preamble and the WU payload, may be generated by turning on and off a plurality of the RUs of the payload of 802.11ax by frequency-shift keying (FSK) or OOK in time. The RUs used for a WU signal may be contiguous or non-contiguous.

In600, WUR signal parameters such as signal length, CP length, or guard interval may be utilized in the setup for WUR in coexistence mode. These parameters may allow the WUR device or receiver to identify the CP length in coexistence mode, discard un-needed information, or the like. When the WUR signal length is undefined or variable, the length of the guard intervals within the OFDM symbol length, such as G1 or G2, may also be configured. In addition, an STA specific sequence may be different from the sequence allocated during the non-coexistence mode to enable the STA to identify CPs to drop or to account for blank transmissions.

Moreover, an 802.11ax capable AP may avoid transmission on RUs or channels used by 802.11ba by disabling or disqualifying one or more specific RUs for 802.11ax data or control transmission. The one or more specific RUs may be signaled in the HE-SIG-B field of the 11ax preamble. As an example, the HE-SIG-B field may indicate that the RU is empty or indicate that the RU may be utilized for a WUR signal. In certain configurations, 802.11ax receivers may be blind to the transmission of the WUR signal.

When an 802.11ba PPDU is generated utilizing one or more RUs of 802.11ax, an 802.11ba signal bandwidth less than a reserved or allocated RU size may be configured. For example, an RU size of 52 tones may be reserved or allocated for transmission of a 5 MHz bandwidth 802.11ba signal. The 802.11ba PPDU sequences and 802.11ax QAM symbols may also be multiplexed in the frequency domain by using OFDM transmission.

The 802.11ba PPDU generated using CP-OFDM may benefit by utilizing shaping sequences and the sequences may utilize one or more allocated RUs for the 802.11ba PPDU. The 802.11ba PPDU preamble and 802.11ba PPDU payload may use different shaping sequences. Also, a technique different than OOK may be utilized for the 802.11ba preamble. Within a useful duration of OFDM, such as 12.8 μs, multiple shaped signals may be utilized and the shaped signals may be OOK symbols with or without coding, such as Manchester coding.

FIG. 7is an example waveform or PPDU type indication for an 802.11ba PPDU700where a WUR preamble sequence (SEQ) and WUR signal (SIG) field may be utilized as waveform indications for a WUR payload. For co-existence with 802.11ax, OFDMA transmission of a waveform with sequence-based OOK symbols or a standalone WUR transmission with OOK symbols and masking may be utilized. For WUR transmission, the WUR preamble SEQ may distinguish different PPDU or waveform formats. In700, the WUR preamble SEQ may indicate the waveform of the WUR SIG field and/or WUR payload. In certain configurations, the WUR SEQ may be the same as the WUR SIG. Also, in certain configurations, the WUR SIG may indicate the waveform of the WUR payload.

In the examples given herewith, an 802.11ba receiver may receive and process non-coexistence configuration or co-existence configuration, scan configured channels for co-existence and non-coexistence preambles, and identify the coexistence preamble. The 802.11ba receiver may also remove overhead from the signal or skip unrelated samples (e.g., CP, GI), and perform energy detection, envelope detection, correlation, or the like. Multiple shaped symbols with DFT-based shaping sequences may be utilized for construction of coexistence signals. To multiplex 802.11ax and 802.11ba information within an OFDM symbol length, 802.11ax OFDM symbols may include multiple shaped signals in time by utilizing a set of reserved or designated subcarriers in one OFDM symbol. A shaped signal may be an OOK signal that may be transmitted without coding or Manchester encoded to reduce the complexity of the WUR receiver.

FIG. 8is an example of multiple OOK symbol generation with DFT-based shaping sequences. Transmitter802may be configured to transmit an 802.11ba PPDU, which includes preamble and data, utilizing CP OFDM. In this example, OOK1 symbol may be data0 (or bit “0”), OOK2 symbol may be data1 (or bit “1”), and OOK3 symbol may be data0 (or bit “0”) to be generated with one DFT sequence as

d3⁢xOOK=D⁡[0g1×1sook⁢⁢1sook⁢⁢2sook⁢⁢30g2×1].Equation⁢⁢(1)
Variables g1and g2may be a number of zeros for padding, that may be indicated by the AP to the primary or 802.11ba radio. The OOK symbols may be given as

where a=(M−h−t)/2, and M is the DFT size, where h and t are non-negative integers. In one configuration, g1or g2may be set to zero to simplify reception. The sequence of three OOK symbols d3xOOKmay be assembled by concatenate component804, converted to the frequency domain by DFT component806having DFT size M, and mapped or multiplexed with other 802.11 information, data, or control807by mapping component808. The output of mapping component808may be processed by IDFT component810of length N and a cyclic prefix added by CP component812prior to transmission by antenna814. In a configuration, mapping component808may multiplex 802.11ba with other QAM symbols, which may be for 802.11ax STAs, in frequency.

Numerology parameters for OOK symbols may be chosen based on 802.11ax numerology where the CP size may be flexible. For different OOK symbols, base sequences may be the same, different, orthogonal to each other, have low cross correlation, or the like. IDFT component810may receive three different sequences for DFT-based shaping to generate OOK symbols which may include Manchester coding. Information816may comprise a 0.8 μs CP, 1.6 μs CP, or 3.2 μs CP, guard interval G1, OOK1 data of duration 4 μs, OOK2 data of duration 4 μs, OOK3 data of duration 4 μs, and guard interval G2 for a total duration of 12.8 μs (818) without the CP.

Since in 802.11ax communication CP duration may be 0.8 μs, 1.6 μs, or 3.2 μs, an 802.11ba receiver may need a signaled indication of the CP duration to detect symbol shape, to correlate the sequence known a priori, to obtain a synchronization point, or the like. A WUR STA may also blindly determine or estimate CP duration. Estimating CP length may be achieved with a preamble based CP indication, CP indication based on transmitter/receiver capability exchanges, the use of a fixed CP level, CP indication sequences in OFDM symbols, or the like. InFIG. 8, duration or lengths 0.8 μs, 1.6 μs, or 3.2 μs are given as examples and any duration may be configured or utilized to meet desired performance or functions.

FIG. 9is an example of an 802.11ba PPDU on 802.11ax RUs and a CP indicating preamble. The format for900may be configured similar to that in600. In900, an 802.11ba preamble902may indicate CP duration for an 802.11ba PPDU on 802.11ax RUs. CP duration may be indicated by specific sequences in useful OFDM duration for the preamble, repeating a different number of repetition rates of the seed sequence, mapping a different repetition rate to different CP durations or OFDM symbol durations, or by the sequences in the preamble utilizing RUs allocated for 802.11ba.

InFIG. 10, an example of CP duration information exchange1000between an 802.11ax/ba STA and 802.11ax AP is given. To decrease receiver complexity for 802.11ba, a configuration for CP capability for 802.11ba to 802.11ax may be utilized. A primary radio on the 802.11ba-capable STA or 802.11ax STA, may send the supported CP duration for its WUR, i.e., LCP_support1016before entering a sleep or idle mode. An 802.11ax AP may store LCP_supportin memory and send the 802.11ba PPDU1018, as shown in detailed 802.11ba PPDU1012, by utilizing an OFDM symbol with the CP duration of LCP_supportin PPDU portions1002,1004, and1008. In detailed 802.11ba PPDU1012, preamble1006may be associated with payload1014having OOK symbols and guard bands1010.

FIG. 11is an example of a fixed CP in a transmission1100where TCP_WURmay be any one of 0.8 μs, 1.6 μs, or 3.2 μs. Transmission1100may include 802.11ax portion1102and 802.11ba PPDU1104having preamble1106and payload1108. In certain configurations, TCP_WURsamples may be prepended as a CP and a receiver may skip the CP region.

FIG. 12is an example of two fixed CP transmissions where OFDM symbol duration may be configured as an integer multiple of OOK symbol duration. ForFIG. 12, when TCP_WUR=3.2 μs, in frame or packet1202a guard interval G1 may be configured between CP and OOK symbols. CP duration TCP_WURmay also be fixed to a certain value such that an OFDM symbol duration including CP TOFDMis integer multiple of OOK symbol duration TOOK. In1204, and as shown in1206, every

TOFDMTOOK-2
other symbols may be the same. In this configuration, 4 OOK symbols may be configured for a duration of 16 μs and the first and fourth OOK symbols may be the same. In this configuration, OOK symbols may remain on the same subcarriers after passing through a multipath channel.

Furthermore, OOK symbols may have TOOK/(TOOK−TCP_WUR) repetitions to meet certain CP configurations of OFDM. For example, there may be

TOOK(TOOK-TCPWUR)=5
CPs for data 0 and data 1. An 802.11ba STA may search for a sequence used as an 802.11ba frame or packet preamble, and start to decode the frame or packet if a valid 802.11ba frame or packet preamble is detected. This operation may be performed without utilizing a L-preamble, L-SIG field, HE preamble, or any non-WUR preamble. Also, at reception in certain configurations the 802.11ba STA may assume that the CP for WUR packet or frame symbols is fixed.

FIG. 13is an example for CP indication sequences. When configuring a CP for 802.11ax and 802.11ba concurrent signals, a set of specific sequences may be utilized at the start or end of the OFDM symbol to allow the 802.11ba receiver to blindly estimate the CP duration or length. These sequences may be orthogonal or quasi-orthogonal to each other. For example, in signals1302and1304, when as an example CP duration is configured as 3.2 μs and IDFT duration or length is 12.8 μs, 1× CP sequence 1 may be utilized for the 802.11ba transmission with OOK symbols within one OFDM symbol. In signals1306and1308, when as an example CP duration is 1.6 μs, 2× CP sequence 2 may be utilized for the 802.11ba transmission with OOK symbols within one OFDM symbol. In signals1310and1312, when as an example CP duration is 0.8 μs, 3× CP sequence 3 may be utilized for the 802.11ba transmission with OOK symbols within one OFDM symbol.

FIG. 14is an example of calculating OOK symbol duration based on 802.11ax OFDM symbols. In 802.11ax, three OFDM symbol durations may be configured for 3 different CP lengths or durations for packets or frames1402,1404, and1406. For orthogonality or quasi-orthogonality of an 802.11ba symbol, an OOK symbol duration may be configured as a common divisor of possible OFDM symbol durations. For example, 802.11ax may utilize durations TOFDM1=16, TOFDM1=14.4, or TOFDM1=13.6 μs as inFIG. 14. In this configuration, the OOK symbol duration may be configured to satisfy condition:

where k, l, m ∈Z. For example, when TOOK=0.8 μs, k, l, m may be 20, 18, or 17. Hence, TOOK=0.8 μs may result in possible OFDM symbol durations that have integer multiples of OOK symbols with minimal residual. The CP part of an 802.11ax OFDM symbol may include a plurality of OOK waveforms that may represent coded bits or uncoded bits. For example, if TOOK=0.8 μs, the CP part may include one symbol in time with Manchester coding (1408) and without coding (1410).

FIG. 15is an example of flexible preamble construction. An 802.11ba preamble may span one or multiple OFDM symbols. With a number of symbols spanned and possible residual time at the end of the OFDM symbol it may be desirable to configure a specific 802.11ba preamble. In signal1502, 802.11ba payload1506may include 802.11ba preamble1504that spans integer multiples of 802.11ax symbols such as k×TOFDM. When an OOK preamble is Tpreamble<k×TOFDM, in signal1508a transmitter may add one or more OOK symbols at the end of 802.11ba preamble1510. The additional OOK symbols may ensure payload alignment with the next OFDM symbol subsequent to 802.11ba payload1512. Signal1508may be configured with a preamble size that is a multiple of the OOK symbol size TOOKto ensure that left-over space fits an OOK symbol. If Tpreamble−k×TOFDM≠m×TOOK, m, k ∈Z, for signal1514a STA or transmitter may pad a fixed sequence or zeros to 802.11ba preamble1516for 802.11ba payload1518such that duration or length is k×TOFDM.

FIG. 16is an example of utilizing blank-symbols with OOK symbols1602. A sequence at the input of a DFT may be modulated to shift shaped symbols, such as OOK symbols, cyclically in time such that the shaped symbols fall into the non-CP region of an OFDM symbol. Non-CP region may be the part of an OFDM symbol which excludes the CP portion and the portion may be utilized to generate the CP of OFDM symbol. For example, the shaped symbol duration, such as 4 μs, and the cyclic prefix related portions of CP-OFDM may be configured without a shaped symbol (1604). If shaped symbols, such as OOK symbols with or without Manchester coding, fall into or overlap a region in the CP duration of an OFDM symbol or the duration where a CP is generated in an OFDM symbol, no data may be transmitted in the OOK symbol (1606).

When the shaped symbol duration for 802.11ba is configured as Took, and in signal1608Tcpand Tusefulis the CP and useful duration of OFDM symbol, respectively, shaped symbols may be spaced apart with Took. InFIG. 16the OFDM symbol duration may be represented as Tofdm=Tcp+Tuseful. In this configuration, the grid spacing for an OOK symbol may be Tookand the grid spacing for OFDM may be Tofdm. In1602, OOK symbols that do not fall in or that are outside CP-related durations of an OFDM symbol, may be transmitted1610as indicated in pattern1604. OOK symbols may be generated with a set of subcarriers, a sequence generated through DFT operation with a circular shift operation, using a sequence table, or the like. A sequence table may include a DFT-based sequence or a combination of the sequences (807).

FIG. 17is an example of utilizing blank-symbols with 802.11ax OFDM symbols1701. The duration or length of 802.11ax OFDM symbols1701may be configured as 16 μs or any other value configured based on desired performance. Blanked-symbols1702may be configured with parameters Took=4 μs, Tcp=3.2 μs, and Tuseful=12.8 μs. Area1704in each symbol may indicate an energy region with or without waveform coding. OOK symbols1706may be generated with or without Manchester coding and shaped. InFIG. 17, the first OOK symbol may be skipped or blanked for a transmission. OOK symbols may then be transmitted with the pattern of {2 OOK, 2 blanked OOK} as indicated by1708. A receiver receiving OOK symbols1706may discard the first OOK symbol and follow the pattern indicated by1708to detect symbols: {2 accept, 2 discard}.

FIG. 18is an example of utilizing blank-symbols for an IDFT output1801. The duration or length of IDFT output1801may be configured as 14.4 μs or any other value configured based on desired performance. Blank-symbols1802may be configured with parameters Took=4 μs, Tcp=1.6 μs, and Tuseful=12.8 μs. Area1804in each symbol may indicate an energy region with or without waveform coding. OOK symbols1806may be generated with or without Manchester coding and shaped. InFIG. 18, the first OOK symbol may be skipped or blanked for a transmission. OOK symbols may then be transmitted with the pattern of {2 OOK, 1 blanked OOK, 3 OOK, 1 blanked OOK} as indicated by1808. A receiver receiving OOK symbols1806may discard the first OOK symbol and follow the pattern to detect symbols: {2 accept, 1 discard, 3 accept, 1 discard}.

FIG. 19is an example of utilizing blank-symbols with a 13.6 μs duration for an IDFT output1901. The duration or length of IDFT output1901may be configured as 13.6 μs or any other value configured based on desired performance. Blank-symbols1902may be configured with parameters Took=4 μs, Tcp=0.8 μs, and Tuseful=12.8 μs. Area1904in each symbol may indicate an energy region with or without waveform coding. OOK symbols1906may be generated with or without Manchester coding and shaped. In the example, the transmitter may transmit first 3 OOK symbols. OOK symbols may be transmitted with the pattern of {1 blanked OOK, 2 OOK, 1 blanked OOK, 3 OOK, 1 blanked OOK, 2 OOK, 1 blanked OOK, 6 OOK} as indicated by 1908. A receiver receiving OOK symbols1906may accept the first 3 OOK symbol and follow the pattern to detect the symbol: {1 discard, 2 accept, 1 discard, 3 accept, 1 discard, 2 accept, 1 discard, 6 accept}.

In the examples given herein, the transmission pattern or sequence of OOK symbols may be configured to be known at a receiver or STA prior to communication. When the transmission pattern is setup prior to transmission, an AP may signal the OOK transmit pattern by using an OOK signal or through a control channel to a STA. The transmission pattern may be configured as a function of OOK and OFDM symbol structures. In addition, the transmission pattern may be blindly estimated at a STA, fixed, based on a CP duration, indicated in a table, or the like.

An STA may set the transmission pattern of a WUR receiver or STA based on the received transmission pattern. A WUR STA or receiver may discard or accept an OOK symbol based on the transmission pattern. When the pattern is signaled during the transmission, sequences for different patterns may be pre-defined. An AP may signal or indicate the OOK transmission pattern by embedding a sequence to the WUR preamble. The WUR STA or receiver may estimate the sequence and discard or accept OOK symbols based on the detected pattern.

When a transmission pattern is blindly estimated by a WUR receiver or STA, an AP may construct the WUR packet by completely or almost completely blanking the CP duration of an OFDM symbol or the duration where CP is generated in an OFDM symbol. In this configuration, a WUR receiver or STA may estimate discarded or valid OOK symbols by utilizing the waveform coding structure of OOK symbols.

In the examples given herein, for each OFDM symbol duration, a different number of shaped signals and symbols such as 1, or 2, 3 OOK symbols, may be generated and the location of OOK symbols may be a function of a transmission pattern. A STA or transmitter may utilize a complex phase rotation in frequency to adjust the position of OOK symbols or the input of the DFT may be circularly shifted. In addition, the sequences for all combinations may be generated and stored and called from memory to generate OOK symbols. For 802.11ax, QAM data and the sequences for blanked-symbol approach may be multiplexed in frequency.

In another configuration, a part of a WUR signal may be located in the guard bands or on the direct current (DC) tones of the OFDM transmission of 802.11ax. Since these subcarriers may be unutilized or underutilized by an 802.11ax STA, and transmitting a WUR PPDU in these subcarriers may increase efficiency.

FIG. 20is an example of concurrent transmission of at least two types of 802.11 information. A PDU of a first 802.11 protocol may be generated (2002) and a preamble and data of a second 802.11 protocol may be generated (2004). The preamble and data of the second 802.11 protocol may be arranged on resources of the PDU of the first 802.11 protocol (2006). The PDU of the first 802.11 protocol, the preamble, and the data of the second 802.11 protocol may be transmitted concurrently (2008).