JP6478131B2 - Multi-clock PHY preamble design and detection - Google Patents

Description

[Cross-reference of related applications]
This application is entitled “Multi-Clock PHY Preamble Design and Detection” filed on Feb. 3, 2012, which claims the benefit of US Provisional Patent Application No. 61 / 441,610, filed Feb. 10, 2011. "Multiclock PHY Preamble Design and Detection" filed on February 28, 2014, which is a continuation of US patent application Ser. No. 13 / 365,963 (currently US Pat. No. 8,665,974). No. 14 / 193,428, a continuation-in-part application. In addition, this application claims the benefit of US Provisional Patent Application No. 61 / 987,115, filed May 1, 2014. This application also relates to US patent application Ser. No. 13 / 365,950 (currently US Pat. No. 8,644,128) entitled “Multi-Clock PHY Preamble Design and Detection” filed on Feb. 3, 2012. . All of the applications referenced above are hereby incorporated herein by reference in their entirety.

  The present disclosure relates generally to multiple communication networks, and more particularly to multiple wireless local area networks that include multiple physical layer modes having multiple clock rates.

  When operating in infrastructure mode, multiple wireless local area networks (WLANs) typically include an access point (AP) and one or more client stations. Multiple WLANs have evolved rapidly over the past decade. Development of multiple WLAN standards such as the American Institute of Electrical and Electronics Engineers (IEEE) 802.11a, 802.11b, 802.11g, and 802.11n standards has improved single user peak data throughput. For example, the IEEE 802.11b standard specifies a single user peak throughput of 11 megabits per second (Mbps), the IEEE 802.11a and IEEE 802.11g standards specify a single user peak throughput of 54 Mbps, and the IEEE 802.11n standard specifies 600 Mbps. Single user peak throughput is specified, and the IEEE 802.11ac standard specifies a single user peak throughput within the Gbps range. Work has begun on the new standard, IEEE 802.11ax, which will provide even greater throughput.

  IEEE 802.11af specifies wireless network operation at sub-1 GHz frequencies. Low frequency communication channels are generally characterized by better propagation quality and extended propagation range compared to higher frequency communication channels. In the past, the sub-1 GHz frequency range is used for wireless communication networks because such frequencies are reserved for other uses (eg, authorized TV frequency bands, radio frequency bands, etc.). Was not. There are several frequency bands that remain unlicensed in the sub-1 GHz range, and the unlicensed frequencies differ in different geographic regions. The IEEE 802.11af standard specifies wireless operation in TV white space (TVWS), that is, a plurality of unused TV channels in the sub-1 GHz frequency band.

  Work on another new standard, IEEE 802.11ah, has begun, which will specify wireless network operation at sub-1 GHz frequencies. The IEEE 802.11ah standard will specify wireless operation in the unlicensed sub-1 GHz frequency band available.

  In one embodiment, the method generates a PHY data unit for transmission according to a wireless communication protocol having a first PHY mode and a second PHY mode. The method includes generating a first preamble portion of a PHY data unit according to a first clock rate, wherein the first preamble portion is formatted according to a first PHY mode when the PHY data unit is transmitted according to a first PHY mode. The first preamble part comprises the step of formatting according to the second PHY mode when the PHY data unit is transmitted according to the second PHY mode. The method also includes generating an OFDM portion of a PHY data unit, the OFDM portion having a second preamble portion including one or more long training fields following the first preamble portion, and the PHY When the data unit is transmitted according to the first PHY mode, it is clocked at the first clock rate, and when the PHY data unit is transmitted according to the second PHY mode, it is clocked at the second clock rate different from the first clock rate. With stages.

  In another embodiment, the communication device is configured to generate a first preamble portion of a PHY data unit for transmission according to a wireless communication protocol having a first PHY mode and a second PHY mode according to a first clock rate. Or a network interface having a plurality of integrated circuits, wherein the first preamble portion is formatted according to the first PHY mode when the PHY data unit is transmitted according to the first PHY mode, and the first preamble portion is When transmitted according to the 2PHY mode, it is formatted according to the second PHY mode. The one or more integrated circuits are further configured to generate an OFDM portion of the PHY data unit, the OFDM portion following the first preamble portion and a second preamble portion including one or more long training fields. A second clock rate that is clocked at a first clock rate when the PHY data unit is transmitted according to the first PHY mode and is different from the first clock rate when the PHY data unit is transmitted according to the second PHY mode. Clocked in.

  In another embodiment, the method processes a PHY data unit received via a wireless communication channel, and the PHY data unit is formatted according to a communication protocol having a first PHY mode and a second PHY mode. The method determines whether the OFDM portion of the PHY data unit is 1) clocked at a first clock rate according to a first PHY mode, or 2) clocked at a second clock rate according to a second PHY mode. Analyzing the first preamble portion of the unit, wherein the first preamble portion is formatted according to the first PHY mode when the PHY data unit is transmitted according to the first PHY mode, and the first preamble portion is the PHY data unit Is transmitted according to the second PHY mode, and is formatted according to the second PHY mode, and the OFDM part comprises the first preamble part. The method also includes 1) if it is determined that the OFDM part is clocked at the first clock rate, and according to the first clock rate, and 2) if it is determined that the OFDM part is clocked at the second clock rate. Processing the OFDM portion of the PHY data unit according to the second clock rate, comprising processing a second preamble portion having one or more long training fields in the OFDM portion. Is provided.

  In yet another embodiment, a communication device comprises a network interface having one or more integrated circuits configured to generate a first preamble portion of a PHY data unit according to a first clock rate, wherein the PHY data unit is The first preamble unit is formatted according to the first PHY mode when the PHY data unit is transmitted according to the first PHY mode, and is used for transmission according to a wireless communication protocol having a first PHY mode and a second PHY mode. The unit is formatted according to the second PHY mode when the PHY data unit is transmitted according to the second PHY mode. The one or more integrated circuits are further configured to generate an OFDM portion of the PHY data unit, the OFDM portion following the first preamble portion and a second preamble portion including one or more long training fields. A second clock rate that is clocked at a first clock rate when the PHY data unit is transmitted according to the first PHY mode and is different from the first clock rate when the PHY data unit is transmitted according to the second PHY mode. Clocked in.

1 is a block diagram of an exemplary wireless local area network (WLAN), according to one embodiment. FIG.

FIG. 4 is a diagram of short range data units in prior art orthogonal frequency division multiplexing (OFDM) configured for AP and / or client stations to transmit over a communication channel, according to one embodiment.

FIG. 6 is a diagram of a short range data unit in prior art OFDM, configured for an AP and / or client station to transmit over a communication channel, according to another embodiment.

FIG. 6 is a diagram of a short range data unit in prior art OFDM, configured for an AP and / or client station to transmit over a communication channel, according to another embodiment.

FIG. 6 is a diagram of a short range data unit in prior art OFDM, configured for an AP and / or client station to transmit over a communication channel, according to another embodiment.

FIG. 3 is a diagram of a short range data unit in a prior art single carrier (SC) configured for an AP and / or client station to transmit over a communication channel, according to one embodiment.

FIG. 3 is a diagram of a first example of a preamble design that determines the clock rate of a data unit and corresponding auto-detection technique, according to one embodiment.

FIG. 4 is a diagram of a second example of a preamble design that determines the clock rate of a data unit and corresponding auto-detection technique, according to one embodiment.

FIG. 6 is a diagram of a third example of a preamble design that determines the clock rate of a data unit and corresponding auto-detection technique, according to one embodiment.

FIG. 6 is a diagram of a fourth example of a preamble design corresponding to an automatic detection technique that determines the clock rate of a data unit, according to one embodiment.

FIG. 9 is a fifth example of a preamble design corresponding to an automatic detection technique for determining the clock rate of a data unit, according to one embodiment.

FIG. 10 is a diagram of a sixth example of preamble design that determines the clock rate of a data unit, corresponding to an automatic detection technique, according to one embodiment.

FIG. 6 is a flow diagram of an example method for generating data units according to a first, second, third, fourth, fifth, or sixth example of preamble design, according to one embodiment.

FIG. 6 is a flow diagram of an example method for automatically detecting a clock rate of a data unit generated according to a first, second, third, fourth, fifth, or sixth example of preamble design, according to one embodiment.

FIG. 3 is a flow diagram of an example method for generating data units according to a first example of preamble design, according to one embodiment.

FIG. 3 is a flow diagram of an example method for automatically detecting a clock rate of a data unit generated according to a first example of preamble design, according to one embodiment.

FIG. 6 is a flow diagram of an example method for generating data units according to a second example of preamble design, according to one embodiment.

FIG. 5 is a flow diagram of an example method for automatically detecting a clock rate of a data unit generated according to a second example of preamble design, according to one embodiment.

FIG. 6 is a flow diagram of an example method for generating data units according to a third example of preamble design, according to one embodiment.

FIG. 6 is a flow diagram of an example method for automatically detecting a clock rate of a data unit generated according to a third example of preamble design, according to one embodiment.

FIG. 6 is a flow diagram of an example method for generating data units according to a fourth or fifth example of preamble design, according to one embodiment.

FIG. 6 is a flow diagram of an example method for automatically detecting a clock rate of a data unit generated according to a fourth or fifth example of preamble design, according to one embodiment.

FIG. 7 is a flow diagram of an example method for generating data units according to a sixth example of preamble design, according to one embodiment.

FIG. 9 is a flow diagram of an example method for automatically detecting a clock rate of a data unit generated according to a sixth example of preamble design, according to one embodiment.

FIG. 3 shows a diagram of a plurality of PHY data units generated according to a plurality of PHY modes with different wireless communication protocols according to an embodiment.

FIG. 3 shows a diagram of a plurality of PHY data units generated according to a plurality of PHY modes with different wireless communication protocols according to an embodiment.

FIG. 4 is a flow diagram of an example method for generating a PHY data unit, according to one embodiment.

FIG. 3 is a flow diagram of an example method for processing PHY data units transmitted over a wireless communication channel, according to one embodiment.

  In embodiments described below, a wireless network device, such as a wireless local area network (WLAN) access point (AP), transmits multiple data streams to one or more client stations, and / or Alternatively, multiple data streams are received from one or more client stations. The AP is configured to communicate with a plurality of client stations according to at least a first communication protocol. In one embodiment, the first communication protocol defines operation in the sub-1 GHz frequency range, and is generally (IEEE802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802. Complies with IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.11ax standards at a relatively low data rate (compared to multiple WLAN systems compliant with 11ax standards) Used for multiple applications that require longer range wireless communication (compared to multiple WLAN systems). The first communication protocol (eg, IEEE 802.11af or IEEE 802.11ah) is referred to herein as a “long range” communication protocol. In some embodiments, the AP also defines operation in a higher frequency range, generally in accordance with one or more other communication protocols commonly used for near field communication at higher data rates. Configured to communicate with a plurality of client stations. Higher frequency communication protocols (eg, IEEE 802.11a, 802.11g, 802.11n, 802.11ac, and 802.11ax standards) are collectively referred to herein as “short range” communication. It is called a protocol.

  In some embodiments, the short range communication protocol provides multiple processing modes, such as a “normal” mode and a “long range” mode (or “range extension” mode). Thus, in some embodiments, an AP is configured to communicate with multiple client stations according to multiple communication modes of a short range communication protocol.

  In some embodiments, a plurality of physical layer (PHY) data units (“long range data units”) that conform to a long range communication protocol or a long range mode of a short range communication protocol may be a short range communication protocol. Same or similar to multiple data units ("short range data units") that conform to the communication protocol or short range mode of the short range communication protocol, but are generated using a lower clock rate. For example, in one embodiment, a device (eg, AP) generates a long range data unit by downsampling or “downclocking” the clock rate used to generate multiple short range data units. To do. Thus, in some embodiments, a single communication device can generate multiple types of data units (eg, long range and short range data units) and the multiple types of data units. Each type has a format generated using a similar but different clock rate. Thus, in some embodiments, two or more differently clocked data units corresponding to two or more different PHY modes coexist simultaneously in the same region. In some embodiments, a single WLAN may have two or more long range communication modes (eg, IEEE 802 in one embodiment) each utilizing multiple data units that are down-clocked from short range data units. A first and second PHY mode that are downclocked to 1/4 and 1/8 of the clock rate of the .11n data unit, respectively.

  All others (eg, for the same Fast Fourier Transform (FFT) size) are equal, but Orthogonal Frequency Division Multiplexing (OFDM) symbols generated with faster clocks use slower clocks in duration. Shorter than the generated OFDM symbol. In some embodiments, all others (eg, for the same Fourier transform (FFT) size) are equal, but an OFDM symbol generated using a faster clock is an OFDM symbol generated using a slower clock. Use a larger tone interval. To properly demodulate a plurality of received data units (eg, IEEE 802.11a, IEEE 802.11n, IEEE 802.11ac, IEEE 802.11ax, IEEE 802.11af, and IEEE 802.11ah data units) including a plurality of OFDM symbols. In addition, the receiving device typically has to know the clock rate used by the transmitting device to generate the received data unit. Thus, different clock rates are used simultaneously in a single domain for different PHY modes, and multiple communication devices without a priori knowledge determine the clock rate of multiple received data units. Or it must be detected automatically. Various embodiments of multiple preamble designs for data units and corresponding receiver techniques for automatically detecting multiple clock rates based on the multiple preamble designs are disclosed herein.

  FIG. 1 is a block diagram of an exemplary wireless local area network (WLAN) 10, according to one embodiment. The AP 14 includes a host processor 15 that is coupled to the network interface 16. The network interface 16 includes a medium access control (MAC) processing unit 18 and a PHY processing unit 20. The PHY processing unit 20 includes a plurality of transceivers 21 that are coupled to a plurality of antennas 24. Although three transceivers 21 and three antennas 24 are shown in FIG. 1, the AP 14 may be configured with a different number of transceivers 21 (eg, 1, 2, 4, 5, etc.) in other embodiments. An antenna 24 may be included.

  The WLAN 10 includes a plurality of client stations 25. Although four client stations 25 are shown in FIG. 1, the WLAN 10 includes a different number of client stations 25 (eg, 1, 2, 3, 5, 6, etc.) in various scenarios and embodiments. Good. Client station 25-1 includes a host processor 26 coupled to network interface 27. The network interface 27 includes a MAC processing unit 28 and a PHY processing unit 29. The PHY processing unit 29 includes a plurality of transceivers 30 that are coupled to a plurality of antennas 34. Although three transceivers 30 and three antennas 34 are shown in FIG. 1, the client station 25-1 may have different numbers (eg, 1, 2, 4, 5, etc.) in other embodiments. Transceiver 30 and antenna 34 may be included. In one embodiment, one, two, or three of client stations 25-2, 25-3, and 25-4 have the same or similar structure as client station 25-1. In these embodiments, the plurality of client stations 25 are structured in the same or similar manner as the client station 25-1 and have the same or different number of transceivers and antennas. For example, in one embodiment, client station 25-2 has only two transceivers and two antennas.

  In various embodiments, the PHY processing unit 20 of the AP 14 is configured to operate in any of a plurality of PHY modes. In some embodiments, each PHY mode corresponds to a specific communication protocol or to a specific mode of the communication protocol. As a result, in some embodiments, each PHY mode corresponds to using a specific clock rate to generate a plurality of corresponding data units. For example, in one embodiment, the first PHY mode corresponds to a short-range communication protocol in which the PHY unit 20 generates a plurality of data units using the first clock rate, and the second PHY mode includes the first PHY unit 20 It corresponds to a long-range communication protocol for generating a plurality of data units using a second clock rate that is down-clocked from the clock rate. As another example, in one embodiment, the first PHY mode corresponds to a short range communication protocol in which the PHY unit 20 generates a plurality of data units using the first clock rate, and the second PHY mode corresponds to the PHY unit 20. Is in a “regular” mode of a long-range communication protocol that generates a plurality of data units using a second clock rate that is down-clocked from the first clock rate (eg, a first clock rate of ¼). Correspondingly, the third PHY mode is a long range in which the PHY unit 20 generates a plurality of data units using a third clock rate that is further down-clocked from the first clock rate (for example, a first clock rate of 1/8). "Extended range" (extended ra) Corresponding to ge) mode. In another example, in one embodiment, the first PHY mode corresponds to a “normal” mode of a short range communication protocol in which the PHY unit 20 generates a plurality of data units using a first clock rate, and the second PHY mode Is a second clock rate at which the PHY unit 20 is down-clocked from the first clock rate (for example, a first clock rate of 1/2, a first clock rate of 1/4, a first clock rate of 1/8, etc.) This corresponds to the “extended range” mode of the short range communication protocol for generating a plurality of data units using.

  The transceiver 21 of the AP 14 is configured to transmit a plurality of generated data units via the antenna 24. Similarly, transceiver 21 is configured to receive a plurality of similar data units via antenna 24. In various embodiments, the PHY processing unit 20 of the AP 14 can receive multiple received data units (eg, any of multiple communication protocols and multiple PHY modes that the PHY processing unit 20 supports for transmission). A plurality of compliant data units).

In some embodiments, the PHY processing unit 29 of the client station 25-1 is configured to generate multiple data units that conform only to a single PHY mode that corresponds to a particular communication protocol and data unit clock rate. The In a plurality of other embodiments, in a manner similar to the PHY processing unit 20, the PHY processing unit 29 is configured to generate a plurality of data units that conform to any of a plurality of PHY modes, and each of the PHYs. The mode corresponds to a specific communication protocol (or a specific mode of the communication protocol) and a clock rate of a specific data unit.

  The transceiver 30 is configured to transmit a plurality of generated data units via the antenna 34. Similarly, transceiver 30 is configured to receive a plurality of data units via antenna 34. The PHY processing unit 29 of the client station 25-1 is connected to one of a plurality of received data units (for example, a plurality of communication protocols and a plurality of PHY modes supported by the PHY processing unit 29 for transmission or reception). A plurality of compliant data units).

  In various embodiments, similar to client station 25-1, each of client stations 25-2, 25-3, and 25-4 can have multiple data units that support only a single PHY mode, or multiple A plurality of data units corresponding to any one of the PHY modes are configured to be transmitted and / or received. In some embodiments, one or more of the client stations 25-1 to 25-4 are not supported by the other one or more of the client stations 25-1 to 25-4. Are configured to transmit and / or receive a plurality of data units corresponding to. For example, in one embodiment, client station 25-1 is configured to transmit and / or receive only a plurality of short range data units clocked at a first rate, while client station 25-2 is more Only long range data units clocked at a slow second rate are configured to transmit and / or receive.

  FIG. 2 is a diagram illustrating an embodiment in which an AP (eg, AP 14 of FIG. 1) and / or a client station (eg, client station 25-1 of FIG. 1) is configured to transmit over a communication channel, according to one embodiment. FIG. 3 is a diagram of a short range data unit 100 in the technology OFDM. The data unit 100 conforms to the IEEE 802.11a standard and occupies a 20 megahertz (MHz) band. The data unit 100 includes a legacy short training field (L-STF) 102 that is typically used for packet detection, initial synchronization, automatic gain control, and the like, and legacy training that is typically used for channel estimation and fine synchronization. A preamble including a field (L-LTF) 104; The data unit 100 is also a legacy signal field (L-SIG) used to carry a plurality of specific PHY parameters of the data unit 100, such as, for example, the modulation type and code rate used to generate the data unit 100. 106. The data unit 100 also has a data part 108. According to some embodiments and / or scenarios, the data portion 108 includes service fields, scrambled PHY service data units (PSDUs), tail bits, and padding bits as needed. Data unit 100 is designed for transmission over a single spatial or spatio-temporal stream in a single input single output (SISO) channel configuration.

  3 is configured for an AP (eg, AP 14 of FIG. 1) and / or a client station (eg, client station 25-1 of FIG. 1) to transmit over a communication channel, according to another embodiment. FIG. 2 is a diagram of a short range data unit 120 in the prior art OFDM. The data unit 120 conforms to the IEEE 802.11n standard, occupies a 20 MHz band, and the WLAN is a client station that conforms to the IEEE 802.11n standard and a client station that conforms to the IEEE 802.11a standard instead of the IEEE 802.11n standard. Corresponds to a “mixed” mode designed for multiple scenarios including both. The data unit 120 includes an L-STF 122, an L-LTF 124, an L-SIG 126, a high throughput signal field (HT-SIG) 128, a high throughput short training field (HT-STF) 130, and M high throughput signals. Has a preamble that includes long training fields (HT-LTFs) 132-1 to 132-M, where M is used to transmit data unit 120 in a multiple-input multiple-output (MIMO) channel configuration An integer that generally corresponds to the number of spatial streams. In particular, according to the IEEE 802.11n standard, the data unit 120 has two HT-LTFs 132 when the data unit 120 is transmitted using two spatial streams, and the data unit 120 has three or four spatial streams. 4 HT-LTFs 132 are transmitted when used. An indication of the specific number of spatial streams being used is included in HT-SIG128. The data unit 120 also has a high throughput data portion (HT-DATA) 134.

  Within data unit 120, L-SIG 126 is modulated according to binary phase shift keying (BPSK), while HT-SIG 128 is modulated according to BPSK (Q-BPSK) on the orthogonal axis. In other words, the modulation of HT-SIG128 is rotated 90 degrees compared to the modulation of L-SIG126. Such modulation allows the receiving device to determine or auto-detect that the data unit 120 conforms to the IEEE 802.11n standard rather than the IEEE 802.11a standard without decoding the entire preamble.

  4 is configured for an AP (eg, AP 14 of FIG. 1) and / or a client station (eg, client station 25-1 of FIG. 1) to transmit over a communication channel, according to another embodiment. FIG. 5 is a diagram of a short range data unit 140 in OFDM, which is prior art. Data unit 140 is designed for multiple scenarios that conform to the IEEE 802.11n standard, occupy a 20 MHz band, and that the WLAN does not include any client station that conforms to the IEEE 802.11a standard rather than the IEEE 802.11n standard. Corresponds to the “Greenfield” mode. The data unit 140 includes a high-throughput green field short training field (HT-GF-STF) 142, a first high-throughput long training field (HT-LTF1) 144, HT-SIG 146, M HT-LTFs 148-1 to 148-M, where M is an integer that generally corresponds to the number of spatial streams used to transmit data unit 140 in a MIMO channel configuration. is there. The data unit 140 also has a data part 150.

  FIG. 5 is configured for an AP (eg, AP 14 of FIG. 1) and / or a client station (eg, client station 25-1 of FIG. 1) to transmit over a communication channel, according to another embodiment. FIG. 6 is a diagram of a short range data unit 170 in the prior art OFDM. The data unit 170 is compliant with the IEEE 802.11ac standard, and includes both a plurality of client stations whose WLAN conforms to the IEEE 802.11ac standard and a plurality of client stations conforming to the IEEE 802.11a standard instead of the IEEE 802.11ac standard. Designed for multiple scenarios. Data unit 170 occupies a 20 MHz bandwidth. In other embodiments or scenarios, a data unit similar to data unit 170 occupies a different bandwidth, such as a 40 MHz, 80 MHz, or 160 MHz bandwidth. The data unit 170 includes an L-STF 172, an L-LTF 174, an L-SIG 176, a first very high throughput signal field (VHT-SIG-A) 178, and an extremely high throughput short training field (VHT-STF). ) 180, M very high throughput long training fields (VHT-LTF) 182-1 to 182-M, where M is an integer, and a second very high throughput signal field (VHT-SIG-B) 184 And a preamble including Data unit 170 also includes a very high throughput data portion (VHT-DATA) 186. In some embodiments, the data unit 170 is a multi-user data unit transmitted by an AP (eg, AP 14 in FIG. 1), and stores information in more than one client station (eg, one in FIG. 1). Alternatively, it is simultaneously transported to a plurality of client stations 25). In multiple such embodiments or scenarios, VHT-SIG-A 178 includes information common to all intended client stations, and VHT-SIG-B 184 provides user-specific information for each of the client stations. Including.

  Within data unit 170, L-SIG 176 and VHT-SIG-A 178 are modulated according to BPSK, while VHT-SIG-B 184 is modulated according to Q-BPSK. Similar to the IEEE802.11n auto-detection function discussed above, such modulation is possible because the receiving device does not decode the entire preamble and the data unit 170 is not in the IEEE802.11a standard, but in the IEEE802.11ac standard. Allows determining or automatically detecting compliance with standards.

  6 is configured for an AP (eg, AP 14 of FIG. 1) and / or a client station (eg, client station 25-1 of FIG. 1) to transmit over a communication channel, according to another embodiment. It is a figure of the data unit 200 of the short range in the single carrier (SC) which is a prior art. In various embodiments, the data unit 200 is compliant with the IEEE 802.11b standard and is modulated by direct sequence spread spectrum (DSSS) or complementary code modulation (CCK). Data unit 200 includes a synchronization (SYNC) field 202 that allows the receiver to detect the presence of data unit 200 and initiate synchronization with the input signal. Data unit 200 also includes a start frame delimiter (SFD) field 204 that signals the start of a frame. The SYNC field 202 and the SFD field 204 form a preamble portion of the data unit 200. Data unit 200 also has a header portion that includes a signal field 206, a service field 808, a length field 210, and a cyclic redundancy check (CRC) field 212. Data unit 200 also includes a PHY service data unit (PSDU) 214, ie, a data portion.

  In various embodiments and / or scenarios, multiple data units compliant with a long range communication protocol (eg, IEEE 802.11af or 802.11ah standard) are described and illustrated above in connection with FIGS. 2-5. Is formatted to be at least substantially the same as specified by the IEEE 802.11a standard, 802.11n standard (mixed mode or greenfield), or 802.11ac standard, but more Transmitted at a lower frequency (eg, sub 1 GHz) using a slower clock rate. In some embodiments and / or scenarios, a plurality of data units that conform to the long range PHY mode (eg, the range extension mode of the 802.11ax standard) of the short range communication protocol is at least a short range. Is formatted to be substantially the same as a plurality of data units conforming to the normal mode of the protocol (eg, the normal mode of the IEEE 802.11ax standard), but transmitted using a slower clock rate.

  In some such embodiments, the transmitting device (eg, AP 14) uses the clock rate used to generate multiple short range data units to generate multiple long range data units. Downclock to 1 / N to a lower clock rate than is possible. Long range data units are therefore typically transmitted over a longer period of time and optionally occupy less bandwidth than the corresponding short range data units. The factor N of the down clock is different according to different embodiments and / or scenarios. In one embodiment, the factor N of the down clock is equal to 4. In other embodiments, other suitable downclock factor (N) values are utilized and the multiple transmission times and bandwidths of multiple long range data units are thus scaled. In some embodiments, the downclock factor N is a power of 2 (eg, N = 2, 4, 8, 16, 32, etc.). In some embodiments, the downclock factor N is a suitable number (eg, N = 5, 10, 20, etc.) that is not a power of two.

For examples of long range data units generated by a downclock, see US patent application Ser. No. 13 / 359,336 filed Jan. 26, 2012 (currently US Pat. No. 8,867,653). The entirety of which is hereby incorporated herein by reference. In some embodiments, as also described in US patent application Ser. No. 13 / 359,336, a long range communication protocol includes a “normal” mode data unit downclocked by a value N ₁ and , And an “extended range” data unit that is down-clocked by the value N ₂ , where N ₂ > N ₁ . Thus, in some embodiments, a device (eg, AP 14 and / or client station 25) is down-clocked at a first rate or even down-clocked depending on whether the device is in normal mode or extended range mode. The long range data unit is selectively transmitted at the second rate.

  Use of multiple clock rates to generate multiple data units that coexist in a particular region (eg, short range and long range data units, and / or normal long range and extended long range data units) As a result, it is useful when a communication device (eg, AP 14 and / or client station 25) that receives the data unit can determine or auto-detect the clock rate used to generate the data unit. As will be described in the following embodiments, the first preamble portion of the data unit automatically detects the clock rate of the data unit using a corresponding technology by the receiving device (for example, data following the first preamble portion). Automatic detection of the clock rate of the OFDM modulation part of the unit). In the embodiments to be described subsequently, the OFDM modulation part of the data unit for which the clock rate is detected is referred to as an “OFDM part”. However, in some embodiments (eg, in some embodiments where the first preamble portion includes an STF), the first preamble portion is also OFDM modulated.

  In the first group of the embodiments corresponding to FIGS. 7-9, including the first, second, and third embodiments, the STF of the preamble of the data unit indicates the clock rate of the OFDM portion of the data unit. Designed. In various embodiments, the STF is used for one or more of packet detection, initial synchronization, automatic gain control, and the like. The OFDM portion includes one or more LTFs used for one or more of channel estimation and fine synchronization in various embodiments. In various embodiments or scenarios, the preamble design of FIGS. 7-9 is utilized in multiple data units transmitted and / or received over a communication channel by a communication device (eg, AP 14 and / or client station 25 of FIG. 1). Is done. Each of FIGS. 7-9 shows two exemplary preambles, each reflecting a PHY mode corresponding to a particular clock rate. In one embodiment, an AP (eg, AP 14) can generate both exemplary preambles (ie, the AP supports multiple PHY modes corresponding to different clock rates), while Each client station (eg, each of the plurality of client stations 25) can generate only one of the exemplary preambles (ie, each client station only has a PHY mode corresponding to a single clock rate). Support). In another embodiment, both the AP and one or more client stations can generate both exemplary preambles.

  For ease of explanation, FIGS. 7-9 show multiple preambles having a first part containing a single STF and only a second part containing a single LTF. However, in other embodiments, different types and / or number of fields are included in the preamble. For example, in one embodiment, the preamble includes multiple LTFs following the STF. As another example, in one embodiment, additional non-LTF fields of the preamble (eg, one or more SIG fields used to inform the receiver of multiple basic PHY parameters) follow the LTF. In some embodiments, the plurality of preambles is the same as any one of the preambles discussed above in connection with FIGS. 2-5, but in connection with FIGS. Having a first STF designed as shown in one of the embodiments described above. For example, in various embodiments, the L-STF 102 of FIG. 2, the L-STF 122 of FIG. 3, the HT-GF-STF 142 of FIG. 4, or the L-STF 172 of FIG. 5 is designed according to the embodiments described below. Is done. In addition, while FIGS. 7-9 each show multiple preambles corresponding to only two possible clock rates, those skilled in the art will recognize that multiple preamble designs and auto-detection techniques described below are different clocks. It will be appreciated that it can be extended to multiple systems that include more than two co-existing PHY modes at the rate.

  In a first embodiment (discussed in connection with FIG. 7), the STF of the preamble is downclocked using the same downclock ratio as the subsequent OFDM part of the data unit. Referring to FIG. 7, OFDM with a first preamble 300 clocked at a first clock rate (eg, in one embodiment, the normal clock rate of an IEEE 802.11a, 802.11n, or 802.11ac data unit). Are included in a plurality of data units. The preamble 300 includes a first preamble part 310 and a second preamble part 314. The first preamble unit 310 is clocked at a first clock rate and includes J repeated STF sequences 318-1 to 318-J. The second preamble part 314 includes at least a first long training field (LTF1) 324 and is included in the OFDM part of the data unit. In some embodiments, the OFDM portion of the data unit also includes a data portion (not shown in FIG. 7).

  A second preamble 330 is included in a plurality of data units having an OFDM portion clocked at a second clock rate that is lower than the first clock rate. In the example of FIG. 7, the OFDM portion of the data unit with preamble 330 is clocked at a rate equal to 1/4 the clock rate of the OFDM portion of the data unit with preamble 300 (eg, in one embodiment, N Generated by downclocking from the first clock rate using = 4). In other embodiments, the second clock rate is different from the first clock rate by a different ratio (eg, in various embodiments, a down clock ratio such as N = 8, 10, 16, etc. is used). . Similar to the preamble 300, the preamble 330 includes a first preamble portion 340 and a second preamble portion 344, and the first preamble portion 340 includes J repeated STF sequences 348-1 to 348-J. Similarly to the preamble 300, the second preamble part 344 includes at least a first long training field (LTF1) 354 and is included in the OFDM part of the data unit. However, unlike the first preamble portion 310 of the preamble 300, the first preamble portion 340 of the preamble 330 is clocked at a lower second clock rate.

  Since the STF sequence 348 is generated using a clock rate that is four times slower than the clock rate used to generate the STF sequence 318, the first preamble unit 310 and the first preamble unit 340 have the same number ( J) including the repeated STF sequence, the first preamble part 340 of the preamble 330 is four times longer than the first preamble part 310 of the preamble 300 in duration. A communication device receiving a plurality of data units having a preamble 300 and a plurality of data units having a preamble 330 is thus capable of determining a clock rate of the OFDM part before demodulating the plurality of OFDM symbols in the OFDM part. The length between the start of the first preamble part and the end of the first preamble part (that is, between the start of the first preamble part and the STF / LTF boundary in the embodiment of FIG. 7) is used. be able to. For this purpose, a receiver performs autocorrelation on each received data unit, as shown in FIG. In one embodiment, the first autocorrelation is performed using a repetition period (time interval) corresponding to the first potential clock rate, and the second autocorrelation uses a repetition period corresponding to the second potential clock rate. Executed. In the example of FIG. 7, the first autocorrelation utilizes a 0.8 μs interval corresponding to the 0.8 μs length of the STF sequence 318 clocked at the first clock rate, and the second autocorrelation is Utilizes a 3.2 μs interval corresponding to the 3.2 μs length of the STF sequence 348 clocked at the clock rate. The first and second autocorrelations are performed simultaneously in one embodiment by a parallel carrier sense circuit and / or software module of a PHY unit, such as the PHY unit 20 or PHY unit 29 of FIG.

  As shown in FIG. 7, the first autocorrelation outputs a first carrier sense signal 380 and the second autocorrelation outputs a second carrier sense signal 384. In some embodiments, the pulse length of the first carrier sense signal 380 includes carrier sensing (illustrated as event CS386) and first preamble (illustrated as event “STF / LTF boundary” 388). This corresponds to the estimated total time between the detection of the transition from the unit 310 to the second preamble unit 314. Similarly, in some embodiments, the pulse length of the second carrier sense signal 384 is the carrier sensing (illustrated as event CS 390) and the event “STF / LTF boundary” 392). This corresponds to the estimated total time between the detection of the transition from the first preamble unit 340 to the second preamble unit 344.

  In some embodiments, the carrier sense signal 380 and / or carrier sense signal 384 is compared to a suitable predetermined threshold and is determined to be “high” if the threshold is met. In some embodiments, detection of CS386 or CS390 includes determining that such a threshold has been met. Further, in some embodiments, after being in a “high” state at a certain time, if the autocorrelation is below such a threshold (or below a different second threshold), the first preamble portion to the second preamble. Transition to part is detected. In some embodiments, detection of STF / LTF boundary 388 or STF / LTF boundary 392 includes detection of such transitions. Although FIG. 7 represents the first carrier sense signal 380 and the second carrier sense signal 384 as continuous pulses, the term “pulse” as used herein refers to continuous pulses and non-continuous pulses (eg, Both of which are not necessarily “high” or “low” in the overall pulse length, but which meet certain suitable predetermined criteria throughout the pulse length.

  In some embodiments, the receiver detects the clock rate of the received data unit by determining which carrier sense signal exhibits strong autocorrelation when operating on the STF section. For example, in one embodiment, if the second carrier sense signal 384 rises but the first carrier sense signal 380 does not rise, the receiver may receive the received STF sequence (and thus the corresponding OFDM of the data unit). Part) is clocked at a lower second clock rate. Conversely, in this embodiment, if the first carrier sense signal 380 rises but the second carrier sense signal 384 does not rise, the receiver may receive the received STF sequence (and thus the corresponding OFDM of the data unit). Part) is clocked at a higher first clock rate. In other words, by way of example, in one embodiment, if the second carrier sense signal 384 meets a suitable detection criterion, but the first carrier sense signal 380 does not meet a suitable detection criterion, the receiver is received. Determine that the STF sequence (and thus the corresponding OFDM portion of the data unit) is clocked at the lower second clock rate. Conversely, in this embodiment, if the first carrier sense signal 380 meets a suitable detection criterion, but the second carrier sense signal 384 does not meet a suitable detection criterion, the receiver may receive a received STF sequence ( Therefore, it is determined that the corresponding OFDM portion of the data unit is clocked at a higher first clock rate.

  However, in some instances, a higher rate clocked STF sequence may trigger carrier sensing corresponding to a lower clocked rate. For example, in some embodiments and / or scenarios, a received data unit having an STF sequence 318 (clocked at a higher first clocked rate) may have a first carrier sense to indicate carrier detection. Both signal 380 and second carrier sense signal 384 may be triggered. In this situation, in one embodiment, the receiver determines the clock rate of the OFDM portion of the data unit based on the pulse length of at least one of the carrier sense signals 380, 384. For example, in one embodiment, each STF includes a sequence of J = 10 (eg, the first preamble section 310 in FIG. 7 is 8.0 μs long, and the second preamble section 340 in FIG. The receiver can detect the clock rate of the OFDM part when the carrier sense signals 380, 384 indicate a length of 8.0 μs between the start of carrier detection and the STF / LTF boundary. Is the first clock rate, and the carrier sense signals 380 and 384 indicate the length of 32 μs between the start of carrier detection and the STF / LTF boundary line, the clock rate of the OFDM part is the second clock rate. Determine the clock rate. In various other embodiments, multiple other algorithms are used. As one example where J = 10, in one embodiment, the receiver determines that the clock rate is the first clock rate if the STF / LTF boundary occurs within 10 μs from the start of carrier detection. When the STF / LTF boundary line occurs after 10 μs or more has elapsed from the start of carrier detection, the clock rate is determined to be the second clock rate. In some embodiments and scenarios where both carrier sense signal 380 and carrier sense signal 384 indicate carrier detection, the receiver observes the pulse length of only one of the plurality of carrier sense signals. To determine the clock rate. In other embodiments, the respective pulse lengths of both carrier sense signals are observed.

  Since both carrier sense signals 380 and 384 may initially indicate carrier sense, the receiver using the example auto-detection technique of FIG. 7 may receive data until sufficient time has elapsed since the start of the first preamble portion. The unit clock rate may not be determined, and therefore may not have sufficient time to dynamically adjust the receiver clock rate based on the detected clock rate. Thus, in one embodiment, a receiver using the automatic detection technique of FIG. 7 operates at a clock rate corresponding to the faster of the first and second clock rates.

  In a second embodiment (discussed in connection with FIG. 8), the STF of the preamble is repeated generated using a constant clock rate, regardless of the clock rate of the subsequent OFDM part of the data unit. Includes STF sequences. However, the STF provides an indication of the clock rate of the OFDM part by including more or fewer repetitions of the STF sequence. Referring to FIG. 8, a data unit having an OFDM portion in which a first preamble 400 is clocked at a first clock rate (eg, a normal clock rate of an IEEE 802.11a, 802.11n, or 802.11ac data unit). include. The preamble 400 includes a first preamble part 410 and a second preamble part 414. The first preamble unit 410 includes J repeated STF sequences 418-1 to 418-J. The second preamble part 414 includes at least a first long training field (LTF1) 424 and is included in the OFDM part of the data unit. In some embodiments, the OFDM portion of the data unit also includes a data portion (not shown in FIG. 8).

  A second preamble 430 is included in a plurality of data units having an OFDM portion that is clocked at a second clock rate lower than the first clock rate. For example, in one embodiment, the OFDM portion of the data unit with preamble 430 is clocked at a rate equal to 1/4 the clock rate of the OFDM portion of the data unit with preamble 400 (eg, in one embodiment, N Generated by downclocking from the first clock rate using = 4). In other embodiments, the second clock rate differs from the first clock rate by a different ratio (eg, in various embodiments, a down clock ratio such as N = 8, 10, 16, etc. is used). Similar to the preamble 400, the preamble 430 includes a first preamble portion 440 and a second preamble portion 444, and the second preamble portion 444 includes at least a first long training field (LTF1) 454, and includes a data unit. It is included in the OFDM part. Further, in one embodiment, the first preamble portion 440 of the preamble 430 is clocked at the same clock rate as the first preamble portion 410 of the preamble 400 (eg, both are clocked at the first clock rate, according to various embodiments). Or both are clocked at a second clock rate). However, unlike the first preamble section 410, the first preamble section 440 includes K repeated STF sequences 448-1 to 448-K, where K is greater than J. In some embodiments, the K / J ratio is equal to the ratio of the first clock rate to the second clock rate. For example, in one embodiment, the first clock rate is four times greater than the second clock rate and the K / J ratio = 4. In other embodiments, the K / J ratio is different from the ratio of the first clock rate to the second clock rate.

  Since the first preamble part 440 of the preamble 430 includes more STF sequences than the first preamble part 410 of the preamble 400, the first preamble part 440 is longer than the first preamble part 410. A communication device that receives the plurality of data units having the preamble 400 and the plurality of data units having the preamble 430 is thus configured to determine the OFDM portion clock rate before demodulating the plurality of OFDM symbols within the OFDM portion. The length between the start of one preamble part and the end of the first preamble part (that is, between the start of the first preamble part and the STF / LTF boundary in the embodiment of FIG. 8) is used. For this purpose, the receiver performs autocorrelation on each received data unit, as shown in FIG. Unlike the first example of FIG. 7, in one embodiment, only one autocorrelation is performed on the received data unit. In one embodiment, autocorrelation is performed using a repetition period (time interval) corresponding to the clock rate used to generate both the first preamble portion 410 and the first preamble portion 440. In the example of FIG. 8, autocorrelation utilizes a 3.2 μs interval corresponding to the 3.2 μs length of the STF sequence 418 and the STF sequence 448.

  FIG. 7 shows multiple alternative autocorrelation outputs corresponding to multiple outputs of different (eg, parallel) carrier sense circuits and / or software modules, while both of the autocorrelation outputs shown in FIG. Represents multiple alternative outputs of the same carrier sense circuit and / or software module. When a data unit having the preamble 400 is received, the first carrier sense signal 480 is output by autocorrelation, and when a data unit having the preamble 430 is received, the second carrier sense signal 484 is output by autocorrelation. Is done. In some embodiments, the pulse length of the first carrier sense signal 480 includes carrier sensing (illustrated as event CS 486) and first preamble (illustrated as event “STF / LTF boundary” 488). This corresponds to the estimated total time between the detection of the transition from the unit 410 to the second preamble unit 414. Similarly, in some embodiments, the pulse length of the second carrier sense signal 484 may be carrier sensing (illustrated as event CS 490) and second (illustrated as event “STF / LTF boundary” 492). This corresponds to the estimated total time between the detection of the transition from the first preamble unit 440 to the second preamble unit 444.

  In some embodiments, the receiver determines the clock rate of the OFDM portion of the received data unit based on the pulse length of the carrier sense signal. For example, J = 4 and K = 16 (for example, in the example of FIG. 8, the first preamble section 410 is 12.8 μs long, and the second preamble section 440 of FIG. In one embodiment (which is 2 μs long), the receiver determines that the clock rate of the OFDM part is when the carrier sense signal indicates a length of 12.8 μs between the carrier sense and the STF / LTF boundary. When it is determined that the clock rate is the first clock rate and the carrier sense signal indicates a length of 51.2 μs between the carrier sense and the STF / LTF boundary line, the clock rate of the OFDM unit is the second clock rate. decide. In various other embodiments, multiple other algorithms are used. Again as an example where J = 4 and K = 16, the receiver, in one embodiment, has a clock rate of the first clock rate when the STF / LTF boundary occurs within 20 μs of carrier sense. When the STF / LTF boundary line occurs after 20 μs or more from the carrier sense, it is determined that the clock rate is the second clock rate. In other embodiments, different suitable values for J and K are utilized.

  Similar to the example autodetection technique of FIG. 7, the example autodetection technique of FIG. 8 may not provide sufficient time to dynamically adjust the receiver clock rate based on the detected clock rate. Accordingly, a receiver using the automatic detection technique of FIG. 8 operates in one embodiment at a clock rate corresponding to the faster of the first and second clock rates.

  In a third embodiment (discussed in connection with FIG. 9), the STF of the preamble is repeated a plurality of times generated using a constant clock rate regardless of the clock rate of the subsequent OFDM part of the data unit. Including STF sequences. However, the repeated STF sequence is augmented with a cover code that provides an indication of the clock rate of the OFDM part. In one embodiment, this preamble design is combined with the preamble design of FIG. 8, and the clock rate of the OFDM part is further indicated by the number of repetitions of the STF sequence. FIG. 9 shows an example preamble design and corresponding auto-detection technique for one embodiment where both the cover code and the number of STF sequences are used to indicate the clock rate of the OFDM part. Referring to FIG. 9, the first preamble 500 was clocked at a first clock rate (eg, the normal clock rate of an IEEE 802.11a, 802.11n, or 802.11ac data unit in various embodiments). It is included in a plurality of data units having an OFDM part. Preamble 500 includes a first preamble unit 510 and a second preamble unit 514. The first preamble unit 510 includes J repeated STF sequences 518-1 to 518-J incremented by the first cover code. The first cover code corresponds to a first clock rate (ie, used to indicate a receiving device where the first clock rate is used for the OFDM portion of the data unit). The second preamble part 514 includes at least a first long training field (LTF1) 524 and is included in the OFDM part of the data unit. In some embodiments, the OFDM portion of the data unit also includes a data portion (not shown in FIG. 9).

  The second preamble 530 is included in a plurality of data units having an OFDM portion that is clocked at a second clock rate lower than the first clock rate. For example, in one embodiment, the OFDM portion of the data unit with preamble 530 may be the data unit with preamble 500 (eg, by down-clocking from the first clock rate using N = 4 in one embodiment). Clocked at a rate equal to ¼ of the OFDM unit clock rate. In other embodiments, the second clock rate differs from the first clock rate by a different ratio (eg, in various embodiments, a down clock ratio such as N = 8, 10, 16, etc. is used). Similar to the preamble 500, the preamble 530 includes a first preamble portion 540 and a second preamble portion 544, and the second preamble portion 544 includes at least a first long training field (LTF1) 554, and includes a data unit. It is included in the OFDM part. Further, in one embodiment, the first preamble portion 540 of the preamble 530 is clocked at the same clock rate as the first preamble portion 510 of the preamble 500 (eg, both are clocked at the first clock rate in accordance with various embodiments). Or both are clocked at a second clock rate). However, unlike the first preamble unit 510, the first preamble unit 540 includes an STF sequence 548 that is incremented by a second cover code that is different from the first cover code. The second cover code corresponds to a lower second clock rate (ie, used to indicate to the receiving device that the OFDM portion of the data unit is clocked at the second clock rate). In one embodiment, the first cover code used in the preamble 500 is only a series of positive ones (ie, [1 1 1 1 ...]), while the second cover code used in the preamble 530 is a series. Alternating positive and negative 1 (ie, [1 −1 1 −1...]).

  As can be seen from FIG. 9, the first preamble portion 540 of the preamble 530 includes K repeated STF sequences 548-1 to 548-K. In embodiments such as the example shown in FIG. 9, the clock rate of the OFDM part is further indicated by the number of STF sequences, and K is greater than J. In some of these embodiments, the K / J ratio is equal to the ratio of the first clock rate to the second clock rate. Alternatively, in some embodiments where the clock rate of the OFDM part is not indicated by the number of STF sequences, K is equal to J.

  Since the cover code of the first preamble section is not known for a particular received data unit, the receiver processes the first preamble portion of the received data unit in two parallel paths in one embodiment. . In one embodiment, in the first path, the receiver attempts to remove or cancel the first cover code, and in the second path, the receiver attempts to remove or cancel the second cover code. In one embodiment, at least a first autocorrelation (processed) of the first preamble part follows a cover code process in the first path, and at least a (processed) parallel second autocorrelation of the first preamble part. However, in the second route, the cover code processing is continued. For example, in one embodiment where the first cover code is a series of 1s and the second cover code is a series of alternating 1s and -1s, the first autocorrelation is a conventional autocorrelation, , One sample of the two windows of the second autocorrelation is multiplied by -1.

  As shown in FIG. 9, the first autocorrelation outputs a first carrier sense signal 580, and the second autocorrelation outputs a second carrier sense signal 584. In some embodiments, the receiver detects the clock rate of the received data unit by determining which carrier sense signal exhibits strong autocorrelation when operating on the STF section. For example, in one embodiment, second carrier sense signal 584 rises (ie, carrier sense 586 has occurred), but first carrier sense signal 580 has not risen (ie, carrier sense 590 has not occurred). , The receiver determines that the OFDM portion of the data unit is clocked at a lower second clock rate. Conversely, in this embodiment, if the first carrier sense signal 580 rises but the second carrier sense signal 584 does not rise, the receiver is clocked at a higher first clock rate in the OFDM portion of the data unit. To decide. In some embodiments, where the clock rate is further indicated by the number of STF sequences (ie, K> J), similar to the auto-detection method of FIG. 8, the receiver may also have carrier sense signal 580 and / or carrier sense signal 584. The clock rate is determined or confirmed based on the pulse length (for example, the position of the STF / LTF boundary line 592 or the STF / LTF boundary line 596). In other words, by way of example, if the second carrier sense signal 584 meets a suitable detection criterion, but the first carrier sense signal 580 does not meet a suitable detection criterion, in one embodiment, the receiver Of the corresponding OFDM part is clocked at a lower second clock rate. Conversely, in this embodiment, if the first carrier sense signal 580 meets a suitable detection criterion, but the second carrier sense signal 584 does not meet a suitable detection criterion, the receiver can transmit the OFDM portion of the data unit. Is clocked at a higher first clock rate.

  A receiver using the example automatic detection technique of FIG. 9 can generally quickly determine the clock rate of the received data unit (eg, based on carrier sense 586 or carrier sense 590). Thus, in one embodiment, the receiving device is configured to dynamically adjust the receiver clock rate to correspond to the determined OFDM part clock rate to save power of the receiving device. In some of these embodiments, the receiving device may receive carrier sense 586 or carrier sense depending on whether a data unit having an OFDM portion clocked at the first clock rate or the second clock rate is received. In response to the occurrence of 590, the receiver clock rate is configured to dynamically adjust. In one embodiment, the receiving device is configured to dynamically adjust the receiver clock rate before processing (eg, demodulating) any portion of the OFDM portion of the data unit.

  In the second group of embodiments, including the fourth, fifth, and sixth embodiments, corresponding to FIGS. 12-10, the SC “extra preamble” portion is the first of the long range data units. It functions as one preamble part, and the additional preamble part is designed to reflect the clock rate of the OFDM part of the data unit. In some embodiments, the multiple formats of the data units of FIGS. 10-12 are similar to the short range data units except for the additional preamble portion. The additional preamble portion includes a SYNC field (eg, similar to a SYNC field according to the IEEE 802.11b standard), and in some embodiments includes an SFD field (eg, similar to an SFD field according to the IEEE 802.11b standard). . In these embodiments, the SYNC field and / or the SFD field are designed to reflect the clock rate of the OFDM portion of the data unit. In some embodiments where data units are generated for transmission over aggregated multiple 20 MHz channels (eg, over 40 MHz, 80 MHz, 160 MHz, etc. channels), the additional preamble portion is in each 20 MHz sub-band. Repeated.

  The additional preamble portion is sampled or clocked at a lower rate than the OFDM portion of the data unit in some embodiments. For example, in one embodiment, the additional preamble portion is downclocked from an 11 MHz IEEE 802.11b rate with a downclock ratio N equal to the downclock ratio used for the OFDM portion of the data unit. As another example, in another embodiment, the additional preamble portion is sampled or clocked at a clock rate approximately 2/3 that of a normal (not downclocked) OFDM portion. In some embodiments where the additional preamble portion is sampled or clocked at a different rate than the OFDM portion, one or more specific requirements for the SC / OFDM boundary between the additional preamble portion and the OFDM portion are met. Yes. For example, in one embodiment, the SC / OFDM boundary requirements specified in the IEEE 802.11g standard are met.

  The preamble design of FIGS. 10-12 may comprise a plurality of data units transmitted and / or received over a communication channel by a communication device (eg, AP 14 and / or client station 25 of FIG. 1) in various embodiments or scenarios. Used in Each of FIGS. 10-12 shows two preamble examples, each preamble example reflecting a PHY mode corresponding to a specific clock rate of the OFDM part. In one embodiment, an AP (eg, AP 14) can generate both exemplary preambles (ie, the AP supports multiple PHY modes corresponding to different clock rates), while Each client station (eg, each of the plurality of client stations 25) can generate only one of the exemplary preambles (ie, each client station only has a PHY mode corresponding to a single clock rate). Support). In another embodiment, both the AP and one or more client stations can generate both exemplary preambles.

  In some embodiments, the preambles of FIGS. 10-12 include multiple types and / or number of fields different from those shown. For example, in one embodiment, the plurality of additional fields are included between the additional preamble portion and the STF (or between the additional preamble portion and the LTF in embodiments without an STF). In some embodiments, the plurality of preambles is the same as any one of the preambles discussed above in connection with FIGS. 2-5, but added at the beginning of the preamble, Having one of the additional preamble parts described below in connection with 10-12. For example, in various embodiments, the additional preamble portion is added before the L-STF 102 in FIG. 2, the L-STF 122 in FIG. 3, the HT-GF-STF 142 in FIG. 4, or the L-STF 172 in FIG. Further, FIGS. 10-12 each show multiple preambles corresponding to only two possible clock rates, while those skilled in the art will recognize that multiple preamble designs and multiple automatic detection techniques described below are different It will be appreciated that it can be extended to multiple systems including three or more co-existing PHY modes having a clock rate of.

  In a fourth embodiment (discussed in connection with FIG. 10), the preamble includes a SYNC field that is generated using a constant clock rate, regardless of the clock rate of the OFDM portion of the corresponding data unit. However, the SYNC field has a specific length based on the clock rate of the OFDM part and allows the receiver to distinguish between multiple clock rates based on the SYNC field. Referring to FIG. 10, the first preamble 600 is clocked at a first clock rate (eg, the normal clock rate of an IEEE 802.11a, 802.11n, or 802.11ac data unit in various embodiments). It is included in a plurality of data units having an OFDM part. The preamble 600 includes a first preamble part 610 (ie, an “additional preamble” part) and a second preamble part 612. First preamble portion 610 includes a SYNC field 614 and an SFD field 616. In one embodiment, the first preamble portion includes a plurality of repetitions of a Barker code. The second preamble unit 612 is included in the OFDM unit of the data unit, and includes an STF 620 and a preamble unit 622 having one or more LTF and SIG fields. In some embodiments, the OFDM portion of the data unit also includes a data portion (not shown in FIG. 10). In an alternative embodiment, preamble 600 does not include SFD field 616. In another alternative embodiment, the SFD field 616 is included in the preamble 600 but the STF 620 is not included.

  The second preamble 630 is included in a plurality of data units having an OFDM portion that is clocked at a second clock rate lower than the first clock rate. For example, in one embodiment, the OFDM portion of the data unit having preamble 630 may be the data unit having preamble 600 (eg, by down-clocking from a first clock rate using N = 4 in one embodiment). Is clocked at a rate equal to ¼ of the clock rate of the OFDM part. In other embodiments, the second clock rate differs from the first clock rate by a different suitable ratio (eg, in various embodiments, a down clock ratio such as N = 2, 8, 10, 16, etc. is used). . Similar to the preamble 600, the preamble 630 includes a first preamble part 640 and a second preamble part 642, and the first preamble part 640 includes a SYNC field 644 and an SFD field 646. Similarly to preamble 600, second preamble section 642 is included in the OFDM section, and includes STF 650 and preamble section 652 having one or more LTF and SIG fields. Further, in one embodiment, the first preamble portion 640 of the preamble 630 is clocked at the same clock rate as the first preamble portion 610 of the preamble 600 (eg, both are clocked at the first clock rate according to various embodiments). Or both are clocked at a second clock rate). However, the SYNC field 644 is longer than the SYNC field 614 of the preamble 600. In one embodiment, the SYNC field 644 includes a number of Barker code repetitions that is greater than the number of repetitions of the same Barker code in the SYNC field 614. For example, if the first clock rate is N times greater than the second clock rate, the SYNC field 644 includes a Barker code repetition number that is N times greater than the same Barker code repetition number in the SYNC field 614. In some embodiments, the SFD field is also utilized to distinguish between the first and second clock rates. In these embodiments, the SFD field 646 of the preamble 630 is different from the SFD field 616 of the preamble 600.

  In one embodiment, a communication device receiving a plurality of data units having a preamble 600 and a plurality of data units having a preamble 630 may reduce the OFDM unit clock rate before demodulating the plurality of OFDM symbols in the OFDM unit. To determine, different SYNC fields of preamble 600 and preamble 630 (in some embodiments, different SFD fields) are utilized. In some embodiments, the receiver performs autocorrelation to detect which SYNC field (and hence which OFDM part clock rate) is used in the received packet.

  In the fifth embodiment (discussed in connection with FIG. 11), regardless of the clock rate of the OFDM portion of the corresponding data unit, the preamble again includes a SYNC field that is generated using a constant clock rate. However, the SYNC field contains a particular repeated sequence based on the clock rate of the OFDM part, allowing the receiver to distinguish between multiple clock rates based on the SYNC field. Referring to FIG. 11, a first preamble 700 is clocked at a first clock rate (eg, a normal clock rate of IEEE 802.11a, 802.11n, or 802.11ac data units in various embodiments). It is included in a plurality of data units having an OFDM part. The preamble 700 includes a first preamble part 710 (ie, an “additional preamble” part) and a second preamble part 712. The first preamble part 710 includes a SYNC field 714 and a start frame delimiter field SFD field 716. The SYNC field 714 includes a first repetition sequence (Ga). In one embodiment, the first repetition sequence is a first Golay sequence. The second preamble part 712 is included in the OFDM part of the data unit, and includes an STF 720 and a preamble part 722 having one or more LTF and SIG fields. In some embodiments, the OFDM portion of the data unit also includes a data portion (not shown in FIG. 11). In an alternative embodiment, preamble 700 does not include SFD field 716. In another alternative embodiment, SFD field 716 is included in preamble 700 but STF 720 is not included.

  A second preamble 730 is included in a plurality of data units having an OFDM portion that is clocked at a second clock rate lower than the first clock rate. For example, in one embodiment, the OFDM portion of the data unit having preamble 730 may be the same as the data unit having preamble 700 (eg, by down-clocking from a first clock rate using N = 4 in one embodiment). Clocked at a rate equal to ¼ of the OFDM unit clock rate. In other embodiments, the second clock rate differs from the first clock rate by a different suitable ratio (eg, in various embodiments, a down clock ratio such as N = 2, 8, 10, 16, etc. is used). . Similar to the preamble 700, the preamble 730 includes a first preamble part 740 and a second preamble part 742, and the first preamble part 740 includes a SYNC field 744. Similarly to the preamble 700, the second preamble section 742 is included in the OFDM section, and includes an STF 750 and a preamble section 752 having one or more LTF and SIG fields. Further, in one embodiment, the first preamble portion 740 of the preamble 730 is clocked at the same clock rate as the first preamble portion 710 of the preamble 700 (eg, both at the first clock rate, according to various embodiments). Clocked, or both clocked at the second clock rate). However, the SYNC field 744 includes a second repetition sequence (Gb) that is different from the first repetition sequence Ga. In some embodiments, the second repeating sequence is a second Golay sequence that is complementary to the first Golay sequence. In some embodiments, the multiple sequences Ga and Gb are suitable complementary sequences rather than multiple Golay sequences. In one embodiment, the plurality of complementary sequences Ga and Gb are selected so that the sum of the corresponding non-periodic autocorrelation coefficients out of phase of the plurality of sequences Ga and Gb is zero. In some embodiments, the plurality of complementary sequences Ga and Gb have a zero or near zero periodic cross-correlation. In another aspect, the plurality of sequences Ga and Gb have aperiodic cross-correlation with narrow main lobes and low level side lobes, or aperiodic autocorrelation with narrow main lobes and low level side lobes. .

  In general, the two complementary sequences of SYNC field 714 and SYNC field 744 have correlation characteristics suitable for detection at the receiving device. In embodiments where the sequence is a Golay sequence, a Golay sequence of length 16, 32, 64, 128, or any other suitable length is utilized for the multiple complementary sequences. In one embodiment, π / 2 chip level rotation is applied to the Golay code sequence in the same manner as specified in the IEEE 802.11ad standard.

  Preamble 730 also includes a start frame delimiter field SFD field 746 that, in some embodiments, is different from SFD field 716. In an alternative embodiment where preamble 700 does not include SFD field 716, preamble 730 does not include SFD field 746. Preamble 700 includes SFD field 716, but in another alternative embodiment that does not include STF 720, preamble 730 includes SFD field 746 and does not include STF 750. In one embodiment, both SFD field 716 and SFD field 746 are each repeated in the SYNC field but increased by a sign flip (ie, are of opposite polarity, eg, -Ga or -Gb) or It includes multiple sequences (eg, multiple Golay sequences). In another embodiment, both SFD field 716 and SFD field 746 include sequences that are complementary to the repeated sequence of the SYNC field. For example, in one embodiment, the SFD field 746 of the preamble 730 includes a first Golay sequence utilized in the SYNC field 714 of the preamble 700, and the SFD field 716 of the preamble 700 is utilized in the SYNC field 744 of the preamble 730. Including a second Golay sequence.

  In one embodiment, a communication device receiving a plurality of data units having a preamble 700 and a plurality of data units having a preamble 730 may reduce the OFDM unit clock rate before demodulating the plurality of OFDM symbols in the OFDM unit. Different SYNC fields of preamble 700 and preamble 730 (in some embodiments, different SFD fields) are utilized to determine. In some embodiments, the receiver performs a plurality of parallel cross-correlations, each of which correlates the received sequence with one of a plurality of possible SYNC field sequences, and which SYNC field (and thus , OFDM part clock rate) is compared in order to determine if it is used in the received packet.

  In the sixth embodiment (discussed in connection with FIG. 12), the preamble includes a SYNC field that is not changed based on the OFDM part clock rate. However, the preamble includes a different SFD field for each different clock rate. Referring to FIG. 12, a first preamble 800 is clocked at a first clock rate (eg, a normal clock rate of IEEE 802.11a, 802.11n, or 802.11ac data units in various embodiments). It is included in a plurality of data units having an OFDM part. The preamble 800 includes a first preamble portion 810 (ie, an “additional preamble” portion) and a second preamble portion 812. The first preamble part 810 includes a SYNC field 814 and a first start frame delimiter (SFD1) field 816. The second preamble part 812 is included in the OFDM part of the data unit, and includes an STF 820 and a preamble part 822 having one or more LTF and SIG fields. In some embodiments, the OFDM portion of the data unit also includes a data portion (not shown in FIG. 12). In an alternative embodiment, preamble 800 does not include STF 820.

  A second preamble 830 is included in a plurality of data units having an OFDM portion that is clocked at a second clock rate lower than the first clock rate. For example, in one embodiment, the OFDM portion of a data unit having a preamble 830 may be (for example, by down-clocking from a first clock rate using N = 4 in one embodiment) of a data unit having a preamble 800. Clocked at a rate equal to ¼ of the OFDM unit clock rate. In other embodiments, the second clock rate differs from the first clock rate by a different suitable ratio (eg, in various embodiments, a down clock ratio such as N = 8, 10, 16, etc. is used). . Similar to the preamble 800, the preamble 830 includes a first preamble part 840 and a second preamble part 842, and the first preamble part 840 includes a SYNC field 844. Similarly to the preamble 800, the second preamble section 842 is included in the OFDM section and includes an STF 850 and a preamble section 852 having one or more LTF and SIG fields. Further, in one embodiment, the first preamble portion 840 of the preamble 830 is clocked at the same clock rate as the first preamble portion 810 of the preamble 800 (eg, both are clocked at the first clock rate according to various embodiments). Or both are clocked at a second clock rate). However, the first preamble portion 840 includes a second start frame delimiter (SFD2) field 846 that is different from the SFD1 field 816. For example, in one embodiment, the SFD1 field 816 is repeated in the SYNC field 814, but includes one or more sequences with sign flips, while the SFD2 field 846 has one or more without sign flips. Including the sequence. As another example, in one embodiment, the SFD1 field 816 includes one or more repetitions of a sequence that is different from the sequence that is repeated one or more times in the SFD2 field 846.

  In one embodiment, a communication device receiving a plurality of data units having a preamble 800 and a plurality of data units having a preamble 830 may reduce the OFDM portion clock rate before demodulating the plurality of OFDM symbols in the OFDM portion. Different SFD fields of preamble 800 and preamble 830 are used to determine. In some embodiments, where the SFD1 field 816 and the SFD2 field 846 contain different sequences, or the SFD2 field 846 contains the same sequence as the SFD1 field 816 but with a code flip, the receiver may determine which SFD (and thus which Multiple parallel cross-correlations are performed to detect whether the OFDM part is used in the received packet.

  FIG. 13 is according to a first, second, third, fourth, fifth, or sixth example of a preamble design (each example of which is shown in FIGS. 7-12), according to one embodiment. FIG. 7 is a flow diagram of an example method 900 for generating a data unit. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) implements method 900 to generate a data unit for transmission over a communication channel. It is configured as follows.

  In block 902, the first preamble portion is generated based on the PHY mode. More specifically, the first preamble part is generated based on at least whether the PHY mode is the first PHY mode or the second PHY mode. In one embodiment, the first and second PHY modes correspond to a plurality of specific communication protocols or specific modes of the communication protocol. For example, in one embodiment, the first PHY mode corresponds to a short range communication protocol and the second PHY mode corresponds to a long range communication protocol. As another example, in one embodiment, the first PHY mode corresponds to the normal mode of the long range communication protocol, and the second PHY mode corresponds to the extended range mode of the long range communication protocol. As another example, in one embodiment, the first PHY mode corresponds to the normal mode of the short range communication protocol, and the second PHY mode corresponds to the extended range mode of the short range communication protocol. In some embodiments, the first preamble portion is also generated based on whether the PHY mode is one or more other possible PHY modes (eg, third PHY mode, fourth PHY mode, etc.). For example, in one embodiment, the first PHY mode corresponds to the short range communication protocol, the second PHY mode corresponds to the normal mode of the long range communication protocol, and the third PHY mode is an extension of the long range communication protocol. Corresponds to the range mode.

  In some embodiments, the first preamble portion is OFDM modulation. For example, in one embodiment, the first preamble portion includes an OFDM modulated STF. In another embodiment, the first preamble part uses SC modulation. For example, in one embodiment, the first preamble portion includes an SC SYNC field. A plurality of more specific examples of a plurality of first preamble parts based on the PHY mode will be described below in connection with FIGS. 15, 17, 19, 21, and 23.

  In block 904, an OFDM portion is generated using the first clock rate or the second clock rate based on the PHY mode. More specifically, the OFDM unit is clocked at the first clock rate when the PHY mode is the first PHY mode, and is clocked at the second clock rate when the PHY mode is the second PHY mode. The second clock rate is lower than the first clock rate (eg, in some embodiments, by an integer factor N). The OFDM part has a second preamble part including one or more LTFs following the first preamble part in the data unit being generated. In some embodiments, the OFDM portion also includes a data portion of a data unit. In some embodiments, the OFDM portion is the same as the corresponding portion of the short range data unit or long range data unit described in connection with FIGS. 2-5. In some of these embodiments, the OFDM part design is based on the PHY mode.

  FIG. 13 shows only blocks 902 and 904 in the method 900, but some embodiments comprise a plurality of additional method elements. For example, in one embodiment, after block 904, a third method element includes a data unit that includes a generated first preamble portion and a generated OFDM portion over a communication channel (eg, a wireless communication channel). Including transmitting. Further, in the flow diagram of the example method 900, the block 904 is shown after the block 902, but in other embodiments, the block 904 occurs before or simultaneously with the block 902.

  FIG. 14 is in accordance with a first, second, third, fourth, fifth, or sixth example of a preamble design (each example of which is shown in FIGS. 7-12), according to one embodiment. FIG. 10 is a flow diagram of an example method 910 for automatically detecting the clock rate of a generated data unit. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 910.

  At block 912, the data unit is received via the communication channel. In an embodiment where method 910 is implemented by an AP, such as AP 14 in FIG. 1, the data unit comprises an antenna, such as one or more antennas 24 in FIG. 1, and a PHY unit, such as PHY unit 20 in FIG. Received via. In an embodiment in which method 910 is implemented by a client station, such as client station 25-1 of FIG. 1, the data unit is an antenna, such as one or more antennas 34 of FIG. 1, and a PHY unit 29 of FIG. Received via the PHY unit. In one embodiment, the communication channel is a wireless communication channel.

  The data unit received at block 912 includes a first preamble portion and an OFDM portion following the first preamble portion. The OFDM portion of the data unit has a second preamble portion that includes one or more LTFs. According to various embodiments, the received data unit is a data unit having the preamble design described in connection with any one of FIGS. 7-12. Additionally or alternatively, according to various embodiments, the received data unit is generated according to the method of any one of FIGS. 15, 17, 19, 21, or 23 described below. Data unit.

  At block 914, the clock rate of the OFDM portion of the data unit received at block 912 is automatically detected or determined based on the first preamble portion of the data unit. More specifically, in one embodiment, it is determined whether the clock rate is a first clock rate corresponding to the first PHY mode or a lower second clock rate corresponding to the second PHY mode. In various embodiments, the multiple PHY modes are similar to any of the multiple PHY modes described in connection with block 902 of method 900 in FIG. Several more specific examples of how the OFDM portion clock rate is determined are described below in connection with FIGS. 16, 18, 20, 22, and 24.

  Although FIG. 14 shows only blocks 912 and 914 in the method 910, some embodiments comprise a plurality of additional method elements. Further, while the method 910 is described in connection with determining the first or second clock rate, some embodiments provide that the clock rate is the third clock rate or the fourth clock rate. And so on (at block 914).

  FIG. 15 is a flow diagram of an example method 920 for generating data units according to a first example of a preamble design (examples of which are shown in FIG. 7), according to one embodiment. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 920 of generating a data unit for transmission over a communication channel. Is done.

  At block 922, it is determined whether the PHY mode of the communication device implementing method 920 is the first PHY mode or the second PHY mode. In one embodiment, the first and second PHY modes correspond to a plurality of specific communication protocols or specific modes of communication protocols as described above in connection with block 902 of method 900 in FIG. .

  If it is determined at block 922 that the PHY mode is the first PHY mode, the flow proceeds to block 924. At block 924, a first preamble portion is generated using a first clock rate corresponding to the first PHY mode. In various embodiments, the first preamble portion is OFDM modulated (eg, includes an OFDM modulated STF in one embodiment) or uses SC modulation (eg, includes an SC SYNC field in one embodiment). ).

  At block 926, an OFDM portion is generated using the first clock rate. The OFDM part has a second preamble part including one or more LTFs following the first preamble part in the data unit being generated. In one embodiment, the OFDM portion also includes a data portion of a data unit. In some embodiments, the OFDM portion is the same as the corresponding portion of the short range data unit or the long range data unit as described in connection with FIGS. 2-5. In some of these embodiments, the design of the OFDM portion is based on the PHY mode determined at block 922.

  On the other hand, if it is determined at block 922 that the PHY mode is the second PHY mode, the flow proceeds to block 930. At block 930, a first preamble portion is generated using a second clock rate corresponding to the second PHY mode. In some embodiments, the first preamble portion generated at block 930 is the same as the first preamble portion generated at block 924, except for the clock rate (and hence its length) of the first preamble portion, or It is the same. For example, in one embodiment, the first preamble portion generated at block 930 uses the same type of modulation (eg, OFDM, SC, etc.), and the same repetition sequence as the first preamble portion generated at block 924 and Contains the number of repetitions of the same sequence. The second clock rate is lower than the first clock rate (eg, in some embodiments by an integer factor N).

  At block 932, the OFDM portion is generated using the second clock rate. The OFDM part has a second preamble part including one or more LTFs following the first preamble part in the data unit being generated. In some embodiments, the OFDM portion generated at block 932 is the same as the OFDM portion generated at block 926 except for the clock rate (and hence its length) of the OFDM portion.

  In some embodiments, the method 920 of FIG. 15 includes a plurality of additional method elements not shown. For example, in one embodiment, after block 926 and after block 932, the additional method elements can include both the generated first preamble portion and the generated OFDM portion over a communication channel (eg, a wireless communication channel). Including transmitting the data unit. Further, in the flow diagram of example method 920, blocks 926 and 932 are shown after blocks 924 and 930, respectively, but in other embodiments, blocks 926 and 932 are before blocks 924 and 930, or Occurs at the same time.

  FIG. 16 is a flow diagram of an example method 940 for automatically detecting the clock rate of a data unit generated according to a first example of a preamble design (example of which is shown in FIG. 7), according to one embodiment. . In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 940.

  At block 942, the data unit is received via a communication channel. In some embodiments, block 942 is similar to block 912 of method 910 in FIG. The data unit received at block 942 includes a first preamble portion and an OFDM portion following the first preamble portion. The OFDM portion of the data unit has a second preamble portion that includes one or more LTFs. According to various embodiments, the received data unit is a data unit having the preamble design described in connection with FIG. Additionally or alternatively, according to various embodiments, the received data unit is a data unit generated according to the method 900 of FIG.

  At block 944, a first autocorrelation of at least a first preamble portion of the data unit received at block 942 is performed, and the first autocorrelation is performed using a first repetition period to output a first carrier sense signal. To do. In one embodiment, the first repetition period is the same as the first potential length of the repetition sequence in the first preamble portion. For example, for the example preamble design shown in FIG. 7, the first iteration period is equal to 0.8 μs or another suitable duration.

  At block 948, a second autocorrelation of at least a first preamble portion of the data unit received at block 942 is performed, and the second autocorrelation is performed using a second repetition period to output a second carrier sense signal. To do. In one embodiment, the second repetition period is the same as the second potential length of the repetition sequence in the first preamble portion, and is different from the first potential length. For example, for the example preamble design shown in FIG. 7, the second repetition period is equal to 3.2 μs or another suitable duration. In one embodiment, the first autocorrelation at block 944 is performed at least partially in parallel with the second autocorrelation at block 948.

  At block 950, whether both the first autocorrelation and the second autocorrelation indicate the presence of a carrier (eg, in one embodiment, the first carrier sense signal and the second carrier sense signal indicate the presence of a carrier). It is determined. For example, in one embodiment, it is determined whether both the first carrier sense signal and the second carrier sense signal are at a “high” level (or any other indicator of relatively strong autocorrelation).

  If it is determined at block 950 that both the first autocorrelation and the second autocorrelation indicate the presence of a carrier, the flow proceeds to block 952. At block 952, the clock rate of the OFDM portion of the data unit received at block 942 is the pulse length of the first carrier sense signal (ie, the first autocorrelation output) and / or the pulse of the second carrier sense signal. Determined based on length (ie, second autocorrelation output). In one embodiment, the clock rate of the OFDM section is such that the first carrier sense signal and / or the second carrier sense signal is at a “high” level (or relatively strong self) for a first total time (eg, 0.8 μs). The first carrier sense signal and / or the second carrier sense signal is determined to be at a second second total time (e.g., 3). If it is at a “high” level (or any other suitable indicator of relatively strong autocorrelation) at .2 μs), it is determined to be a lower second clock rate. In some embodiments, the determination at block 950 includes determining that the pulse length of the first and / or second carrier sense signal is a first length range (eg, less than 10 μs), or a second length range ( For example, by determining if it is greater than 10 μs). In one embodiment, the pulse lengths of the first and second carrier sense signals are 1) sensing the carrier and 2) from the first preamble portion of the received data unit to the second preamble portion of the received data unit. Corresponds to the total time between detection of transitions.

  On the other hand, if it is determined at block 950 that the first autocorrelation output or the second autocorrelation output (but not both) indicates the presence of a carrier, flow proceeds to block 954. At block 954, the clock rate of the OFDM portion of the data unit received at block 942 is determined based on which autocorrelation indicates the presence of a carrier. For example, in one embodiment, the clock rate of the OFDM portion is determined to be the first clock rate if the first autocorrelation (not the second) indicates carrier sense and (not the first). If the second autocorrelation indicates carrier sense, it is determined to be a lower second clock rate.

  In some embodiments, the method 940 includes a plurality of additional method elements not shown in FIG. For example, in one embodiment, the method 940 includes providing a receiver clock rate corresponding to the first higher potential clock rate of the received data unit prior to receiving the data unit at block 942. Prepare. Further, while the method 940 is described in connection with determining the first and second clock rates, some embodiments may include a third clock rate (e.g., similar to blocks 944 and 948), And whether the OFDM portion clock rate is one of these additional potential clock rates is also determined at block 952 or 954. The In embodiments utilizing a third or later clock rate, block 950 is modified to determine if more than one autocorrelation output indicates the presence of a carrier, and block 952 includes: Modified to take into account autocorrelation output of 3 or later.

  FIG. 17 is a flow diagram of an example method 960 of generating a data unit according to a second example of a preamble design (an example of which is shown in FIG. 8), according to one embodiment. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) implements method 960 to generate a data unit for transmission over a communication channel. It is configured as follows.

  At block 962, it is determined whether the PHY mode of the communication device implementing method 960 is the first PHY mode or the second PHY mode. In various embodiments, block 962 is similar to block 922 of method 920 in FIG.

  If it is determined at block 962 that the PHY mode is the first PHY mode, the flow proceeds to block 964. At block 964, a first iteration number (ie, one or more iterations) of the sequence is generated at the first preamble portion. In some embodiments, the first preamble portion is generated using a first clock rate that corresponds to the clock rate of the OFDM portion when in the first PHY mode, while in other embodiments, the first preamble portion is One preamble part is generated using a second clock rate corresponding to the clock rate of the OFDM part when in the second PHY mode. In one embodiment, the repeated sequences of the first preamble portion are OFDM modulated (eg, in one embodiment, an STF OFDM modulation sequence).

  At block 968, the OFDM portion is generated using the first clock rate. In various embodiments, block 968 is similar to block 926 of method 920 of FIG.

  If it is determined at block 962 that the PHY mode is the second PHY mode, the flow proceeds to block 970. At block 970, a second repetition number of the sequence is generated at the first preamble portion. The second number of repetitions is greater than the first number of repetitions generated at block 964, causing the first preamble portion to be longer than the first preamble portion generated at block 964. In one embodiment, each repetition sequence generated at block 970 is the same as each repetition sequence generated at block 964. For example, in one embodiment, the multiple sequences of the first preamble portion are generated at block 970 using the same clock rate that is used to generate the multiple sequences of the first preamble portion at block 964, and the block Both the plurality of sequences of the first preamble portion generated at 964 and 970 are STF OFDM modulation sequences.

  At block 972, the OFDM portion is generated using the second clock rate. In various embodiments, block 972 is similar to block 932 of method 920 in FIG.

  In some embodiments, the method 960 of FIG. 17 includes a plurality of additional method elements not shown. For example, in one embodiment, after block 968 and block 972, an additional method element includes both a generated first preamble portion and a generated OFDM portion over a communication channel (eg, a wireless communication channel). Including transmitting the data unit. Further, in the flow diagram of example method 960, blocks 968 and 972 are shown after blocks 964 and 970, respectively, but in other embodiments, blocks 968 and 972 are before blocks 964 and 970, respectively. Or at the same time.

  18 is a flow diagram of an example method 980 for automatically detecting the clock rate of a data unit generated according to a second example of a preamble design (an example of which is shown in FIG. 8), according to one embodiment. . In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 980.

  At block 982, the data unit is received via a communication channel. Block 982 is similar to block 912 of method 910 in FIG. 14 in some embodiments. The data unit received at block 982 includes a first preamble portion and an OFDM portion following the first preamble portion. The OFDM portion of the data unit has a second preamble portion that includes one or more LTFs. According to various embodiments, the received data unit is a data unit having the preamble design described in connection with FIG. Additionally or alternatively, according to various embodiments, the received data unit is a data unit generated according to the method 960 of FIG.

  At block 984, autocorrelation of at least a first preamble portion of the data unit received at block 982 is performed, and the autocorrelation outputs a carrier sense signal.

  At block 988, the clock rate of the OFDM portion of the data unit received at block 982 is determined based on the pulse length (ie, autocorrelation output) of the carrier sense signal. In one embodiment, the clock rate of the OFDM portion is such that the carrier sense signal is at a “high” level (or any other indicator of relatively strong autocorrelation) in the first total time (eg, 0.8 μs). In some cases, the first clock rate is determined and the carrier sense signal is “high” level (or any other of a relatively strong autocorrelation) at a longer second total time (eg, 3.2 μs). If it is, the lower second clock rate is determined. In some embodiments, the determination at block 988 is that the pulse length of the carrier sense signal is in a first length range (eg, less than 10 μs) or a second length range (eg, greater than 10 μs). It is executed by determining. In one embodiment, the pulse length depends on the number of repeated sequences in the first preamble portion of the data unit. In one embodiment, the pulse length of the carrier sense signal (eg, pulse duration in the carrier sense signal) is 1) sensing the carrier and 2) data received from the first preamble portion of the received data unit. This corresponds to the estimated total time between the detection of the transition to the second preamble portion of the unit.

  In some embodiments, the method 988 includes a plurality of additional method elements not shown in FIG. For example, in one embodiment, the method 980 provides a receiver clock rate corresponding to a first higher potential clock rate of the plurality of received data units prior to receiving the data units at block 982. Including stages. Further, method 980 has been described in connection with determining the first and second clock rates, while some embodiments correspond to a third clock rate, a fourth clock rate, etc. (eg, It is also determined at block 988 whether it includes a plurality of additional method elements (similar to block 984) and the clock rate of the OFDM portion is one of these additional potential clock rates.

  FIG. 19 is a flow diagram of an example method 1000 for generating data units according to a third example of preamble design (examples of which are shown in FIG. 9), according to one embodiment. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) implements method 1000 to generate a data unit for transmission over a communication channel. It is configured as follows.

  At block 1002, it is determined whether the PHY mode of the communication device implementing the method 1000 is the first PHY mode or the second PHY mode. In various embodiments, block 1002 is similar to block 922 of method 920 in FIG.

  If it is determined at block 1002 that the PHY mode is the first PHY mode, the flow proceeds to block 1004. At block 1004, a first iteration number (ie, one or more iterations) of the sequence (ie, one or more iterations) is generated in the first preamble portion. Block 1004 is similar to block 964 in method 960 of FIG. 17 in one embodiment.

  In block 1008, the first preamble portion generated in block 1004 is increased using the first cover code. For example, in one embodiment, the first preamble portion is incremented with a sequence of all ones (ie, this does not change the polarity of all bits in all repeated sequences of the first preamble portion). In one embodiment where the first cover code is an all-in-one sequence, increasing the first preamble portion at block 1008 simply includes not performing any cover code processing operations on the first preamble portion. In one embodiment where the first cover code is an all-one sequence, block 1008 is omitted.

  In block 1010, the OFDM portion is generated using a first clock rate corresponding to the first PHY mode. In various embodiments, block 968 is similar to block 926 of method 920 in FIG.

  If it is determined at block 1002 that the PHY mode is the second PHY mode, the flow proceeds to block 1012. At block 1012, a second iteration number (ie, one or more iterations) of the sequence is generated in the first preamble portion. In one embodiment, the second number of iterations is the same as the first number of iterations generated at block 1004 (ie, the number of iterations, and thus the length of the first preamble portion is PHY mode, or the length of the OFDM portion). Does not reflect the clock rate). In another embodiment, the second number of iterations is greater than the first number of iterations generated at block 1004, resulting in the first preamble portion being longer than the first preamble portion generated at block 1004. In one embodiment, each iteration sequence generated at block 1012 is the same as each iteration sequence generated at block 1004. For example, in one embodiment, multiple sequences of the first preamble portion are generated at block 1012 using the same clock rate that is used to generate the multiple sequences of first preamble portion at block 1004, Both the plurality of sequences of the first preamble part generated at 1004 and 1012 are STF OFDM modulation sequences.

  At block 1014, the first preamble portion generated at block 1012 is increased using a second cover code that is different from the first cover code used for the first PHY mode. For example, in one embodiment where the first cover code is an all-one sequence, the first preamble portion is increased at block 1014 using a series of alternating positive and negative ones (eg, one embodiment). This changes the polarity of all bits in each second instance of the sequence). In one embodiment where the second cover code is an all-one sequence, incrementing the first preamble portion at block 1014 simply includes not performing any cover code processing operations on the first preamble portion. In one embodiment where the second cover codes are all 1 sequences, block 1014 is omitted.

  In block 1018, the OFDM portion is generated using a second clock rate corresponding to the second PHY mode. In various embodiments, block 1018 is similar to block 932 of method 920 in FIG.

  In some embodiments, the method 1000 of FIG. 19 includes a plurality of additional method elements not shown. For example, in one embodiment, after block 1010 and block 1018, an additional method element includes both a generated first preamble portion and a generated OFDM portion over a communication channel (eg, a wireless communication channel). Transmitting a data unit containing. Further, the sequence of blocks in each path of method 1000 is different in various embodiments, and / or one or more of the blocks of method 1000 are performed concurrently with other blocks. The For example, in one embodiment, blocks 1004 and 1008 (or blocks 1012 and 1014) occur after or in parallel with block 1010 (or block 1018).

  FIG. 20 is a flow diagram of an example method 1020 for automatically detecting the clock rate of a data unit generated according to a third example of a preamble design (example of which is shown in FIG. 9), according to one embodiment. . In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 1020.

  At block 1022, the data unit is received via a communication channel. In some embodiments, block 1022 is similar to block 912 of method 910 in FIG. The data unit received at block 1022 includes a first preamble portion and an OFDM portion following the first preamble portion. The OFDM portion of the data unit has a second preamble portion that includes one or more LTFs. According to various embodiments, the received data unit is a data unit having a preamble design described in connection with FIG. Additionally or alternatively, according to various embodiments, the received data unit is a data unit generated according to the method 1000 of FIG.

  At block 1024, at least a first preamble portion of the data unit received at block 1022 is processed to remove or cancel the first possible cover code. For example, in one embodiment, the first possible cover code is a series of 1s utilized by multiple transmitting devices that transmit data units in a first PHY mode using a first clock rate. In one embodiment where the first possible cover code is a series of ones, block 1024 is omitted.

  At block 1028, a first autocorrelation (as processed at block 1024) of at least the first preamble portion is performed. The first autocorrelation is performed using the first repetition period and outputs a first carrier sense signal. In one embodiment, block 1028 is similar to block 944 of FIG.

  At block 1030, at least the first preamble portion of the data unit received at block 1022 is processed to remove or cancel the second possible cover code. For example, in one embodiment, where the first possible cover code is a series of ones utilized by multiple transmitting devices in the first PHY mode using the first clock rate, the second possible cover code is the first A series of alternating positive and negative ones utilized by a plurality of transmitting devices in the second PHY mode using a second clock rate different from the clock rate. In one embodiment, block 1030 is executed in parallel with block 1024. In one embodiment where the second possible cover code is a series of ones, block 1030 is omitted.

  At block 1032, a second autocorrelation (as processed at block 1030) of at least the first preamble portion is performed, the second autocorrelation is performed using the second repetition period, and the second carrier sense signal is Output. In one embodiment, block 1032 is similar to block 948 of FIG. 16 (eg, in one embodiment, block 1032 is executed in parallel with block 1028).

  At block 1034, the clock rate of the OFDM portion of the data unit received at block 1022 is determined based on which autocorrelation output indicates the presence of a carrier. For example, in one embodiment, the first carrier sense signal output by the first autocorrelation performed at block 1028 indicates the presence of a carrier (eg, outputs a “high” level, or a relatively strong self The second carrier sense signal output by the second autocorrelation performed in block 1032 indicates the presence of a carrier (eg, “high”). The clock rate is determined to be the second clock rate.

  Since each of the first and second autocorrelations follows a process that attempts to remove or cancel one of the plurality of alternative cover codes of the preamble design scheme, the most of the first and second carrier sense signals Only one that is likely will indicate the presence of a carrier. Furthermore, this carrier sensing generally does not have to wait until the pulse length is known, but occurs near the beginning of the carrier sense signal pulse. Thus, in one embodiment, the receiver clock is dynamically adjusted based on the determination at block 1034 to correspond to the clock rate of the received data unit.

  In some embodiments, the method 1020 includes a plurality of additional method elements not shown in FIG. 20, such as, for example, dynamically adjusting the receiver clock described above. Further, while the method 1020 is described in connection with determining the first and second clock rates, some embodiments correspond to a third clock rate, a fourth clock rate, etc. (eg, A plurality of additional method elements (similar to blocks 1024 and 1028) are provided, and it is also determined at block 1034 whether the clock rate of the OFDM portion is one of these additional potential clock rates.

  FIG. 21 is a flow diagram of an example method 1040 for generating data units according to a fourth or fifth example of a preamble design (examples of which are shown in FIGS. 10 and 11, respectively), according to one embodiment. is there. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) implements method 1040 to generate a data unit for transmission over a communication channel. It is configured as follows.

  At block 1042, it is determined whether the PHY mode of the communication device implementing method 1040 is the first PHY mode or the second PHY mode. In various embodiments, block 1042 is similar to block 922 of method 920 in FIG.

  If it is determined at block 1042 that the PHY mode is the first PHY mode, the flow proceeds to block 1044. At block 1044, a first SYNC field is generated in the first preamble portion, which is an SC “additional preamble” portion as discussed above. In some embodiments, the first SYNC field includes a repeating sequence (eg, a repeating Barker sequence, Golay code sequence, etc., according to various embodiments). In one embodiment, the first SYNC field is the same or substantially similar to a SYNC field that conforms to the IEEE 802.11b standard.

  At block 1048, a start frame delimiter (SFD field) is generated. The SFD field is included in the first preamble part and follows the SYNC field generated at block 1044. In one embodiment, the SFD field is the same or substantially similar to an SFD field that conforms to the IEEE 802.11b standard. In one embodiment, the SFD field is clocked at the same rate as the SYNC field.

  At block 1050, the OFDM portion is generated using a first clock rate corresponding to the first PHY mode. In various embodiments, block 1050 is similar to block 926 of method 920 in FIG.

  If it is determined at block 1042 that the PHY mode is the second PHY mode, the flow proceeds to block 1052. In block 1052, a second SYNC field different from the first SYNC field generated in block 1044 is generated in the first preamble portion. In one embodiment, the second SYNC field has a length that is different from the length of the first SYNC field generated at block 1044. Alternatively, in another embodiment, the second SYNC field includes a repeating sequence that is complementary to the repeating sequence of the first SYNC field. For example, in one embodiment, the first and second SYNC fields include a plurality of complementary Golay code sequences. In one embodiment, the second SYNC field is the same or substantially similar to a SYNC field that conforms to the IEEE 802.11b standard. Further, in one embodiment, the second SYNC field is clocked at the same rate as the first SYNC field.

  At block 1054, an SFD field is generated. The SFD field is included in the first preamble part and follows the SYNC field generated in block 1052. In one embodiment, the SFD field generated at block 1054 is the same as the SFD field generated at block 1048. In another embodiment, the SFD field generated at block 1054 is different from the SFD field generated at block 1048. For example, in one embodiment where the first and second SYNC fields generated at blocks 1044 and 1052 include complementary Golay code sequences Ga and Gb, respectively, the SFD field generated at block 1048 is one of Gb. Or the SFD field generated at block 1054 includes one or more repetitions of Ga. In one embodiment, the SFD field is clocked at the same rate as the SYNC field.

  At block 1058, the OFDM portion is generated using a second clock rate corresponding to the second PHY mode. In various embodiments, block 1058 is similar to block 926 of method 920 in FIG.

  In some embodiments, the method 1040 of FIG. 21 includes a plurality of additional method elements not shown. For example, in one embodiment, after block 1050 and block 1058, an additional method element includes both a generated first preamble portion and a generated OFDM portion over a communication channel (eg, a wireless communication channel). Transmitting a data unit containing. Further, the sequence of blocks in each path of method 1040 is different in various embodiments, and / or one or more blocks of method 1040 are executed concurrently with a plurality of other blocks. For example, in one embodiment, blocks 1044 and 1048 (or blocks 1052 and 1054) occur after or in parallel with block 1050 (or block 1058). Further, in some embodiments, blocks 1048 and 1054 are omitted (ie, the generated first preamble portion, and thus the generated data unit does not include an SFD, regardless of the PHY mode). Still further, in some embodiments where blocks 1048 and 1054 are included (ie, SFD is included in the first preamble portion), the OFDM portion generated in block 1050 and block 1058 does not include an STF, The LTF of the OFDM part follows immediately after the SFD of the first preamble part.

  FIG. 22 illustrates a method for automatically detecting the clock rate of a data unit generated according to a fourth or fifth example of a preamble design (examples of which are shown in FIGS. 10 and 11, respectively), according to one embodiment. FIG. 10 is a flow diagram of Example 1060. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 1060.

  At block 1062, the data unit is received via a communication channel. In some embodiments, block 1062 is similar to block 912 of method 910 in FIG. The data unit received at block 1062 includes a SYNC field, and in some embodiments includes a first preamble portion that is an SC “additional preamble” that includes the SFD that follows the SYNC field. The OFDM part of the data unit follows the first preamble part. The OFDM portion of the data unit includes one or more LTFs, and in some embodiments, a second preamble portion that includes an STF preceding the LTF. According to various embodiments, the received data unit is a data unit having the preamble design described in connection with FIG. 10, or a data unit having the preamble design described in connection with FIG. is there. Additionally or alternatively, according to various embodiments, the received data unit is a data unit generated according to the method 1040 of FIG.

  At block 1064, the clock rate of the OFDM portion of the data unit received at block 1062 is automatically detected or determined based on the SYNC field in the first preamble portion of the data unit. More specifically, in one embodiment, it is determined whether the clock rate is a first clock rate corresponding to the first PHY mode or a lower second clock rate corresponding to the second PHY mode. . In various embodiments, the PHY mode is similar to any of the multiple PHY modes described in connection with block 902 of method 900 in FIG.

  In some embodiments, the clock rate of the OFDM portion is determined based on the length of the SYNC field (eg, if the received data unit conforms to the fourth example of the preamble design of FIG. 10). In several other embodiments, the clock rate of the OFDM portion is determined based on a repeating sequence of SYNC fields (eg, when the received data unit conforms to the fourth example of the preamble design of FIG. 11). For example, in one embodiment, the clock rate is determined based on whether a first Golay code sequence is included in the SYNC field or a complementary second Golay code sequence is included in the SYNC field. In one embodiment where the received data unit also utilizes a plurality of different SFDs to indicate the clock rate, the step of determining the clock rate at block 1064 is performed on the SFD of the first preamble portion of the received data unit. And determining a clock rate based on.

  Although FIG. 22 shows only blocks 1062 and 1064 in the method 1060, some embodiments include a plurality of additional method elements. Further, while method 1060 has been described in connection with determining a first or second clock rate, some embodiments have a clock rate of a third clock rate or a clock rate of a third. Alternatively, it is further determined (at block 1064) whether it is the fourth clock rate or the like.

  FIG. 23 is a flow diagram of an example method 1080 for generating data units according to a sixth example of preamble design (examples of which are shown in FIG. 12), according to one embodiment. In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) implements method 1080 to generate a data unit for transmission over a communication channel. Configured to do.

  At block 1082, it is determined whether the PHY mode of the communication device implementing method 1080 is the first PHY mode or the second PHY mode. In various embodiments, block 1082 is similar to block 922 of method 920 in FIG.

  If it is determined at block 1082 that the PHY mode is the first PHY mode, the flow proceeds to block 1084. At block 1084, a SYNC field is generated in the first preamble portion, which is the SC “additional preamble” portion discussed above. In some embodiments, the SYNC field includes a repeating sequence (eg, repeating Barker sequence, Golay code sequence, etc.), according to various embodiments. In one embodiment, the SYNC field is the same or substantially similar to a SYNC field that conforms to the IEEE 802.11b standard.

  At block 1088, a first SFD field is generated. The first SFD field is included in the first preamble part and follows the SYNC field generated at block 1084. In one embodiment, the first SFD field is the same or substantially similar to an SFD field that conforms to the IEEE 802.11b standard. In one embodiment, the SFD field is clocked at the same rate as the SYNC field.

  At block 1090, the OFDM portion is generated using a first clock rate corresponding to the first PHY mode. In various embodiments, block 1090 is similar to block 926 of method 920 in FIG.

  If it is determined at block 1082 that the PHY mode is the second PHY mode, the flow proceeds to block 1092. At block 1092, the SYNC field is generated in the first preamble portion. In one embodiment, the SYNC field is the same or substantially the same as the SYNC field generated at block 1084.

  At block 1094, a second SFD field that is different from the first SFD field is generated. For example, in one embodiment, the second SFD field includes a sequence that repeats in the SYNC field but has a code flip, while the first SFD field includes the same sequence of SYNC fields that do not have a code flip. As another example, in one embodiment, the second SFD field includes one or more repetitions of a different sequence than the sequence repeated one or more times in the first SFD field. The second SFD field is included in the first preamble part and follows the SYNC field generated in block 1092. In one embodiment, the second SFD field is clocked at the same rate as the SYNC field.

  At block 1098, the OFDM portion is generated using a second clock rate corresponding to the second PHY mode. In various embodiments, block 1098 is similar to block 926 of method 920 in FIG.

  In some embodiments, the method 1080 of FIG. 23 includes a plurality of additional method elements not shown. For example, in one embodiment, after block 1090 and block 1098, an additional method element includes both a generated first preamble portion and a generated OFDM portion over a communication channel (eg, a wireless communication channel). Transmitting a data unit containing. Further, the sequence of blocks in each path of method 1080 is different in various embodiments, and / or one or more blocks of method 1080 are executed concurrently with other blocks. For example, in one embodiment, blocks 1084 and 1088 (or blocks 1092 and 1094) occur after or simultaneously with block 1090 (or block 1098). In some embodiments, the OFDM portion generated at block 1090 and block 1098 does not include an STF, and the LTF of the OFDM portion immediately follows the SFD.

  FIG. 24 is a flow diagram of an example method 1100 for automatically detecting the clock rate of a data unit generated according to a sixth example of a preamble design (an example of which is shown in FIG. 12), according to one embodiment. . In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 1100.

  At block 1102, the data unit is received via a communication channel. In some embodiments, block 1102 is similar to block 912 of method 910 in FIG. The data unit received at block 1102 has a first preamble portion which is an SC “additional preamble” including a SYNC field and an SFD following the SYNC field. The OFDM part of the data unit follows the first preamble part. The OFDM portion of the data unit includes one or more LTFs, and in some embodiments, a second preamble portion that includes an STF preceding the LTF. However, in some embodiments, the second preamble part does not include an STF and the LTF follows immediately after the SFD of the first preamble part. According to various embodiments, the received data unit is a data unit having the preamble design described in connection with FIG. Additionally or alternatively, according to various embodiments, the received data unit is a data unit generated according to the method 1080 of FIG.

  In block 1104, the clock rate of the OFDM portion of the data unit received in block 1102 is automatically detected or determined based on the SFD field in the first preamble portion of the data unit (not on the SYNC field). More specifically, in one embodiment, it is determined whether the clock rate is a first clock rate corresponding to the first PHY mode or a lower second clock rate corresponding to the second PHY mode. In various embodiments, the PHY mode is similar to any of the PHY modes described in connection with block 902 of method 900 in FIG.

  In some embodiments, the SFD field (and hence clock rate) of the OFDM part is determined by performing parallel cross-correlation. For example, in one embodiment, a first cross-correlation correlates a received SFD sequence with a first potential SFD sequence corresponding to a first clock rate, and a second cross-correlation causes a received SFD sequence to Correlate with a second potential SFD sequence corresponding to 2 clock rates.

  Although FIG. 24 shows only blocks 1102 and 1104 in method 1100, some embodiments include a plurality of additional method elements. Further, while the method 1100 is described in connection with determining the first and second clock rates, some embodiments may be that the clock rate is the third clock rate or the clock rate is the first. It is further determined (at block 1104) whether it is a 3 or 4 clock rate.

  FIG. 25 shows a diagram of a PHY data unit generated according to multiple PHY modes with different wireless communication protocols, according to one embodiment. In various embodiments or scenarios, the PHY data unit of FIG. 25 is transmitted and / or received by a communication device (eg, AP 14 and / or client station 25 of FIG. 1) over a communication channel and utilized in multiple data units. Is done. FIG. 25 shows two PHY data unit formats, each of which reflects a PHY mode corresponding to a specific clock rate of the OFDM part. In one embodiment, an AP (eg, AP 14) can generate both exemplary PHY data units. That is, the AP supports multiple PHY modes corresponding to different clock rates), while each client station (eg, each of the multiple client stations 25) is one of the exemplary PHY data units. Only (ie, each client station supports only a PHY mode corresponding to a single clock rate). In another embodiment, both the AP and one or more client stations can generate both exemplary PHY units.

  In one embodiment, the first data unit 1200 corresponds to a first PHY mode (eg, normal PHY mode) and the second data unit 1230 corresponds to a second PHY mode (eg, range extension PHY mode). Each of the first data unit 1200 and the second data unit 1230 includes a first preamble unit 1210 and an OFDM unit 1212. The OFDM unit 1212 includes a second preamble unit 1220 and a data unit 1222.

  In one embodiment, the first preamble unit 1210 is clocked at the first clock rate in both the first PHY mode and the second PHY mode. On the other hand, the OFDM unit 1212 is clocked at a first clock rate with respect to the data unit 1200 (to be transmitted according to the first PHY mode), whereas according to one embodiment, the OFDM unit 1212 is (first PHY mode). Clocked to the data unit 1230 at a second clock rate, which is different from the first clock rate. In some embodiments, the second clock rate is lower than the first clock rate, while in other embodiments, the second clock rate is higher than the first clock rate. In some embodiments, the second clock rate is a suitable fraction of the first clock rate (1/2, 1/4, 1/8, 1/10, 1/16, etc. thereof). In some embodiments, the second clock rate is a suitable integer multiple of the first clock rate (2x, 4x, 8x, 10x, 16x, etc. thereof).

  In some embodiments, the first preamble section 1210 is formatted such that the first preamble section 1210 is formatted to indicate whether the OFDM section 1212 is clocked at a first clock rate or a second clock rate. This is the same as both the first PHY mode and the second PHY mode. For example, in one embodiment, the first preamble unit 1210 has the same duration in both the first PHY mode and the second PHY mode. As another example, in one embodiment, the field in the first preamble portion 1210 has the same duration in both the first PHY mode and the second PHY mode. On the other hand, in one embodiment, the field (eg, signal field) in the first preamble portion 1210 includes data indicating whether the OFDM portion 1212 is clocked at the first clock rate or the second clock rate. As another example, in one embodiment, when the PHY data unit is transmitted according to the second PHY mode, compared to the first PHY mode, at least some pilot tones of the set of pilot tones in the first preamble portion 1210 are Flipped. Thus, in one embodiment, the pilot tone in the first preamble portion 1210 indicates whether the OFDM portion 1212 is clocked at the first clock rate or the second clock rate. As another example, in one embodiment, a portion of the first preamble portion 1210 is modulated differently compared to the first PHY mode when the PHY data unit is transmitted according to the second PHY mode. Thus, in one embodiment, the modulation of at least a portion of the first preamble portion 1210 indicates whether the OFDM portion 1212 is clocked at a first clock rate or a second clock rate.

  In one embodiment, the first preamble unit 1210 includes a legacy unit (not shown). In one embodiment, the first preamble portion includes a SYNC field (not shown). In one embodiment, the first preamble portion includes an STF (not shown) and a signal field (not shown). In one embodiment, the second preamble portion 1220 includes one or more LTFs (not shown) and a SIG field (not shown). In one embodiment, the first preamble portion 1210 includes a first SIG field, and the second preamble portion 1220 includes a second SIG field.

  In one embodiment, the first preamble unit 1210 is configured such that a communication device receiving the data unit 1200 or the data unit 1230 determines the clock rate of the OFDM unit 1212 before demodulating a plurality of OFDM symbols in the OFDM unit 1212. analyse. For example, in some embodiments, the receiver may use one or more 1) first preamble units 1210 to determine whether the OFDM unit 1212 is clocked at a first clock rate or a second clock rate. 2) (for example, in the SIG field of the preamble part 1210), 2) a pilot tone in the first preamble part 1210, and / or 3) modulation of at least a part of the first preamble part 1210, and the like.

  FIG. 26 shows a diagram of PHY data units generated according to multiple PHY modes with different wireless communication protocols, according to one embodiment. In various embodiments or scenarios, the PHY data unit of FIG. 26 is utilized in multiple data units transmitted and / or received by a communication device (eg, AP 14 and / or client station 25 of FIG. 1) over a communication channel. Is done. FIG. 26 shows two PHY data unit formats, each of which reflects a PHY mode corresponding to a specific clock rate of the OFDM part. In one embodiment, an AP (eg, AP 14) can generate both exemplary PHY data units (ie, the AP supports multiple PHY modes corresponding to different clock rates). On the other hand, each client station (eg, each of multiple client stations 25) can generate only one of the exemplary PHY data units (ie, each client station supports a single clock rate). Only support PHY mode). In another embodiment, both the AP and one or more client stations can generate both exemplary PHY units.

  In one embodiment, the first data unit 1300 corresponds to a first PHY mode (eg, normal PHY mode) and the second data unit 1350 corresponds to a second PHY mode (eg, range extension PHY mode). Each of the first data unit 1300 and the second data unit 1350 includes a first preamble unit 1310 and an OFDM unit 1312. The OFDM unit 1312 includes a second preamble unit 1320 and a data unit 1322.

  In one embodiment, the first preamble portion 1310 is clocked at the first clock rate in both the first PHY mode and the second PHY mode. On the other hand, the OFDM unit 1312 is clocked at a first clock rate with respect to the data unit 1300 (to be transmitted according to the first PHY mode), whereas according to one embodiment, the OFDM unit 1312 is (first PHY mode). Clocked to the data unit 1350 at a second clock rate, where the second clock rate is different from the first clock rate. In some embodiments, the second clock rate is lower than the first clock rate, while in other embodiments, the second clock rate is higher than the first clock rate. In some embodiments, the second clock rate is a suitable fraction of the first clock rate (1/2, 1/4, 1/8, 1/10, 1/16, etc. thereof). In some embodiments, the second clock rate is a suitable integer multiple of the first clock rate (2x, 4x, 8x, 10x, 16x, etc. thereof). In some embodiments, the first clock rate corresponds to a first tone interval, while the second clock rate corresponds to a second tone interval that is different from the first tone interval. In some embodiments, the second tone interval is a suitable fraction of the first tone interval (1/2, 1/4, 1/8, 1/10, 1/16, etc. thereof). In some embodiments, the second tone interval is a suitable integer multiple of the first tone interval (2x, 4x, 8x, 10x, 16x, etc.). In some embodiments, the first clock rate corresponds to a first OFDM symbol duration, while the second clock rate corresponds to a second OFDM symbol duration that is different from the first OFDM symbol duration. In some embodiments, the second OFDM symbol duration is a suitable integer multiple of the first OFDM symbol duration (2x, 4x, 8x, 10x, 16x, etc.). In some embodiments, the second OFDM symbol duration is a suitable fraction of the first OFDM symbol duration (1/2, 1/4, 1/8, 1/10, 1/16, etc. thereof).

  In some embodiments, the first preamble portion 1310 is formatted such that the first preamble portion 1310 indicates whether the OFDM portion 1312 is clocked at a first clock rate or a second clock rate. Is the same in both the first PHY mode and the second PHY mode. For example, in one embodiment, the first preamble unit 1310 has the same duration in both the first PHY mode and the second PHY mode. As another example, in one embodiment, the plurality of fields in the first preamble portion 1310 have the same duration in both the first PHY mode and the second PHY mode. On the other hand, in one embodiment, the field (eg, signal field) in the first preamble portion 1310 includes data indicating whether the OFDM portion 1312 is clocked at the first clock rate or the second clock rate. As another example, in one embodiment, when the PHY data unit is transmitted according to the second PHY mode, compared to the first PHY mode, at least some pilot tones of the set of pilot tones in the first preamble portion 1310. Multiple signals are flipped. Thus, in one embodiment, the plurality of pilot tones in the first preamble section 1310 indicate whether the OFDM section 1312 is clocked at the first clock rate or the second clock rate. As another example, in one embodiment, when the PHY data unit is transmitted according to the second PHY mode, a portion of the first preamble portion 1310 is modulated differently compared to the first PHY mode. Thus, in one embodiment, the modulation of at least a portion of the first preamble portion 1310 indicates whether the OFDM portion 1312 is clocked at the first clock rate or the second clock rate.

  First preamble unit 1310 includes a legacy unit 1330. In one embodiment, the legacy unit 1330 includes an L-STF field, an L-LTF field, and an L-SIG field arranged as shown in FIG. First preamble portion 1310 also includes a high efficiency WLAN (HEW) signal (HEW-SIGA) field 1334. In one embodiment, HEW-SIGA field 1334 includes data indicating whether OFDM portion 1312 is clocked at a first clock rate or a second clock rate. The first preamble part also includes a HEW-STF field 1336. In other embodiments, the first preamble portion 1310 omits some of the fields discussed above and / or includes a plurality of other suitable fields.

  The second preamble part 1320 includes one or more HEW-LTF 1340 and a HEW-SIGB field 1344 when the data unit is transmitted according to the first PHY mode. In one embodiment, the second preamble portion 1320 omits one or both of 1) a plurality of HEW-LTF 1340 and / or 2) a HEW-SIGB field 1344 and / or a plurality of other suitable Field.

  The second preamble part 1320 includes one or more HEW-LTF 1354 and a HEW-SIGB field 1358 when the data unit is transmitted according to the second PHY mode. In one embodiment, the second preamble portion 1320 omits one or both of 1) a plurality of HEW-LTF 1354 and / or 2) a HEW-SIGB field 1358 and / or a plurality of other suitable Field.

  In one embodiment, the data unit 1350 spans a suitable bandwidth, and the plurality of HEW-LTFs 1354 include different bandwidth portions that together span the bandwidth of the data unit 1350. Similarly, in one embodiment, HEW-SIGB field 1358 includes different bandwidth portions that together span the bandwidth of data unit 1350. Similarly, in one embodiment, the data portion 1322 includes a plurality of different bandwidth portions 1362 that together span the bandwidth of the data unit 1350.

  In one embodiment, the first preamble unit 1310 is configured such that a communication device that receives the data unit 1300 or the data unit 1350 determines the clock rate of the OFDM unit 1312 before demodulating a plurality of OFDM symbols in the OFDM unit 1312. analyse. For example, in some embodiments, the receiver may: 1) in the first preamble portion 1310 (eg, HEW− to determine whether the OFDM portion 1312 is clocked at the first clock rate or the second clock rate). One or more of the data (in the SIGA field 1334), 2) multiple pilot tones in the first preamble section 1310, and / or 3) modulation of at least a portion of the first preamble section 1310, etc. are analyzed.

  FIG. 27 is a flow diagram of an example method 1400 for generating a PHY data unit for transmission according to a wireless communication protocol having a first PHY mode and a second PHY mode, according to one embodiment. In one embodiment, method 1400 is an implementation of the method of FIG.

  In some embodiments, the method 1400 is utilized to generate PHY data units in accordance with the multiple formats shown in FIGS. 25 and / or 26. For illustrative purposes only, the method 1400 is described in connection with FIG. However, in other embodiments, the method 1400 is utilized to generate a plurality of PHY data units according to a plurality of other suitable formats. For example, the method 1400 is utilized to generate multiple PHY data units according to the multiple formats discussed above in connection with FIGS. 10-12, according to some embodiments.

  In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) implements method 1400 to generate a data unit for transmission over a communication channel. It is configured as follows. For example, in one embodiment, PHY processing unit 20 (and / or a client station such as client station 25-1) is configured to implement method 1400 to generate a data unit for transmission over a communication channel. The

  In block 1404, it is determined whether the PHY data unit is transmitted according to the first PHY mode or the second PHY mode. If block 1404 determines that a PHY data unit is to be transmitted according to the first PHY mode, flow proceeds to block 1408. At block 1408, the first preamble portion of the PHY data unit is generated according to the first clock rate. Further, the first preamble part is generated so that the first preamble part is formatted according to the first PHY mode. In one embodiment, the first preamble portion is formatted to indicate that the OFDM portion following the first preamble portion is clocked at a first clock rate. By way of example, in one embodiment, the first preamble portion corresponds to the first preamble portion 1210 in the first PHY mode discussed above in connection with FIG. As another example, in one embodiment, the first preamble portion corresponds to the first preamble portion 1310 in the first PHY mode discussed above in connection with FIG.

  At block 1412, the OFDM portion is generated according to the first clock rate. For example, in one embodiment, the OFDM portion corresponds to the OFDM portion 1212 in the first PHY mode discussed above in connection with FIG. As another example, in one embodiment, the OFDM portion corresponds to the OFDM portion 1312 in the first PHY mode discussed above in connection with FIG.

  If block 1404 determines that the PHY data unit is to be transmitted according to the second PHY mode, flow proceeds to block 1416. At block 1416, the first preamble portion of the PHY data unit is generated according to the first clock rate. Further, the first preamble part is generated so that the first preamble part is formatted according to the second PHY mode. In one embodiment, the first preamble portion is formatted to indicate that the OFDM portion following the first preamble portion is clocked at the second clock rate. By way of example, in one embodiment, the first preamble portion corresponds to the first preamble portion 1210 in the second PHY mode discussed above in connection with FIG. As another example, in one embodiment, the first preamble portion corresponds to the first preamble portion 1310 in the second PHY mode discussed above in connection with FIG.

  At block 1420, the OFDM portion is generated according to the second clock rate. For example, in one embodiment, the OFDM portion corresponds to the OFDM portion 1212 in the second PHY mode discussed above in connection with FIG. As another example, in one embodiment, the OFDM portion corresponds to the OFDM portion 1312 in the second PHY mode discussed above in connection with FIG.

  In some embodiments, the method 1400 of FIG. 27 includes a plurality of additional method elements not shown. For example, in one embodiment, after block 1412 and block 1420, an additional method element includes both a generated first preamble portion and a generated OFDM portion over a communication channel (eg, a wireless communication channel). Transmitting a PHY data unit including. Further, in the flow diagram of example method 1400, blocks 1412 and 1420 are shown after blocks 1408 and 1416, respectively, but in other embodiments, blocks 1412 and 1420 are before blocks 1408 and 1416. Or at the same time.

  FIG. 28 is a flow diagram of an example method 1500 for processing a data unit transmitted over a wireless communication channel according to a wireless communication protocol having a first PHY mode and a second PHY mode, according to one embodiment.

  In some embodiments, the method 1500 is utilized to process multiple PHY data units in accordance with the multiple formats shown in FIG. 25 and / or FIG. For illustrative purposes only, the method 1500 is described in connection with FIG. However, in other embodiments, the method 1500 is utilized to process multiple PHY data units received according to multiple other suitable formats. For example, according to some embodiments, the method 1500 is utilized to process multiple PHY data units according to the multiple formats discussed above in connection with FIGS. 10-12.

  In some embodiments, an AP such as AP 14 of FIG. 1 (and / or a client station such as client station 25-1) is configured to implement method 1500 to process data units transmitted over the communication channel. Is done. For example, in one embodiment, PHY processing unit 20 (and / or a client station such as client station 25-1) is configured to implement method 1500 to process data units transmitted over a communication channel.

  At block 1504, the data unit is received via a communication channel. In some embodiments, block 1504 is similar to block 912 of method 910 in FIG. The data unit received at block 1504 includes a first preamble portion and an OFDM portion following the first preamble portion. The OFDM portion of the data unit has a second preamble portion that includes one or more LTFs. According to various embodiments, the received data unit has a format, such as the multiple formats shown in FIG. 25 and / or FIG. Additionally or alternatively, according to various embodiments, the received data unit is a data unit generated according to the method 1400 of FIG. The first preamble portion of the PHY data unit is generated according to the first clock rate.

  At block 1508, it is determined whether the first preamble portion is formatted according to the first PHY mode or the second PHY mode. In one embodiment, the first preamble portion is formatted to indicate whether the OFDM portion following the first preamble portion is clocked at the first clock rate or the second clock rate. By way of example, in one embodiment, the first preamble portion corresponds to the first preamble portion 1210 as discussed above in connection with FIG. As another example, in one embodiment, the first preamble portion corresponds to the first preamble portion 1310 discussed above in connection with FIG.

  In one embodiment, block 1508 determines whether a field (eg, a signal field) in the first preamble portion includes data indicating whether the OFDM portion is clocked at the first clock rate or the second clock rate. including. As another example, in one embodiment, it is determined whether at least some pilot tones of the set of pilot tones in the first preamble portion are flipped compared to the first PHY mode. Thus, in one embodiment, the plurality of pilot tones in the first preamble portion indicate whether the OFDM portion is clocked at the first clock rate or the second clock rate. As another example, in one embodiment, it is determined whether a portion of the first preamble portion is modulated differently compared to the first PHY mode. Thus, in one embodiment, the modulation of at least a portion of the first preamble portion indicates whether the OFDM portion 1212 is clocked at the first clock rate or the second clock rate.

  If it is determined at block 1508 that the OFDM portion is clocked at the first clock rate, the flow proceeds to block 1512. At block 1512, the OFDM portion is processed according to the first clock rate.

  On the other hand, if it is determined at block 1508 that the OFDM portion is clocked at the second clock rate, the flow proceeds to block 1516. At block 1516, the OFDM portion is processed according to the second clock rate.

  In some embodiments, the method 1500 includes a plurality of additional method elements not shown in FIG. For example, in one embodiment, the method 1500 comprises providing a receiver clock rate corresponding to the second clock rate of the received data unit prior to receiving the data unit at block 1504.

  In one embodiment, the method generates a PHY data unit for transmission according to a wireless communication protocol having a first PHY mode and a second PHY mode. The method includes generating a first preamble portion of a PHY data unit according to a first clock rate, wherein the first preamble portion is in accordance with a first PHY mode when the PHY data unit is transmitted according to a first PHY mode. Formatted, the first preamble part is formatted according to the second PHY mode when the PHY data unit is transmitted according to the second PHY mode. The method also comprises generating an OFDM portion of the PHY data unit, where the OFDM portion includes a second preamble portion having one or more long training fields following the first preamble portion; When the PHY data unit is transmitted according to the first PHY mode, it is clocked at the first clock rate, and when the PHY data unit is transmitted according to the second PHY mode, it is clocked at the second clock rate different from the first clock rate.

  In other embodiments, the method includes any suitable combination of one or more of the following features.

  Generating the first preamble portion includes generating a set of pilot tones in the first preamble portion to indicate whether the PHY data unit is generated according to the first PHY mode or the second PHY mode.

  When the PHY data unit is transmitted according to the second PHY mode, the signals of at least some pilot tones of the set of pilot tones are flipped compared to the first PHY mode.

  Generating the first preamble part includes generating a first preamble part having a field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode.

  The field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode is 1) after the legacy part in the first preamble part, and 2) the short training field in the first preamble part. Is a signal field that occurs before

  The second clock rate is lower than the first clock rate.

  The second clock rate is a fraction of the first clock rate.

  The second clock rate is 1/4 of the first clock rate.

  The second clock rate is faster than the first clock rate.

  An OFDM part is generated, whereby a plurality of OFDM symbols in the OFDM part have a first duration when a PHY data unit is transmitted according to a first PHY mode, and a plurality of OFDM symbols in the OFDM part When the data unit is transmitted according to the second PHY mode, it has a second duration, where the second duration is different from the first duration.

  The second duration is longer than the first duration.

  An OFDM part is generated, whereby a plurality of OFDM symbols in the OFDM part have a first tone interval when a PHY data unit is transmitted according to a first PHY mode, and a plurality of OFDM symbols in the OFDM part are When the data unit is transmitted according to the second PHY mode, it has a second tone interval, where the second tone interval is different from the first tone interval.

  The second tone interval is smaller than the first tone interval.

  In another embodiment, a communication device comprises a network interface having one or more integrated circuits, the one or more integrated circuits being wireless having a first PHY mode and a second PHY mode according to a first clock rate. Configured to generate a first preamble portion of a PHY data unit for transmission according to a communication protocol, wherein the first preamble portion is formatted according to the first PHY mode when the PHY data unit is transmitted according to the first PHY mode; The first preamble part is formatted according to the second PHY mode when the PHY data unit is transmitted according to the second PHY mode. The one or more integrated circuits are further configured to generate an OFDM portion of the PHY data unit, where the OFDM portion follows the first preamble portion and includes one or more long training fields. The second PHY data unit is clocked at the first clock rate when transmitted according to the first PHY mode, and is different from the first clock rate when the PHY data unit is transmitted according to the second PHY mode. Clocked at the clock rate.

  In other embodiments, the apparatus includes any suitable combination of one or more of the following features.

  The one or more integrated circuits are further configured to generate a set of pilot tones for the first preamble portion to indicate whether the PHY data unit is generated according to the first PHY mode or the second PHY mode.

  When the PHY data unit is transmitted according to the second PHY mode, the signals of at least some pilot tones of the set of pilot tones are flipped compared to the first PHY mode.

  The one or more integrated circuits are further configured to generate a first preamble portion having a field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode.

  The field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode is 1) after the legacy part in the first preamble part, and 2) the short training field in the first preamble part. Is a signal field that occurs before

  The second clock rate is lower than the first clock rate.

  The second clock rate is a fraction of the first clock rate.

  The second clock rate is 1/4 of the first clock rate.

  The second clock rate is faster than the first clock rate.

  An OFDM part is generated, whereby a plurality of OFDM symbols in the OFDM part have a first duration when a PHY data unit is transmitted according to a first PHY mode, and a plurality of OFDM symbols in the OFDM part When the data unit is transmitted according to the second PHY mode, it has a second duration, where the second duration is different from the first duration.

  The second duration is longer than the first duration.

  An OFDM part is generated, whereby a plurality of OFDM symbols in the OFDM part have a first tone interval when a PHY data unit is transmitted according to a first PHY mode, and a plurality of OFDM symbols in the OFDM part are When the data unit is transmitted according to the second PHY mode, it has a second tone interval, where the second tone interval is different from the first tone interval.

  The second tone interval is smaller than the first tone interval.

  In another embodiment, a method processes a PHY data unit received via a wireless communication channel, wherein the PHY data unit is formatted according to a communication protocol having a first PHY mode and a second PHY mode. Is done. The method determines whether the OFDM portion of the PHY data unit is 1) clocked at a first clock rate according to the first PHY mode or at a second clock rate according to the second PHY mode. Analyzing the first preamble portion, wherein the first preamble portion is formatted according to the first PHY mode when the PHY data unit is transmitted according to the first PHY mode, and the first preamble portion is the PHY data unit; Is transmitted according to the second PHY mode, it is formatted according to the second PHY mode, and the OFDM part follows the first preamble part. The method also includes 1) if it is determined that the OFDM part is clocked at the first clock rate, and 2) if it is determined that the OFDM part is clocked at the second clock rate, according to the first clock rate, Processing the OFDM portion of the PHY data unit according to the second clock rate, the method comprising processing a second preamble portion in the OFDM portion having one or more long training fields.

  In other embodiments, the method includes any suitable combination of one or more of the following features.

  The step of analyzing the first preamble portion analyzes the set of pilot tones in the first preamble portion to determine whether the PHY data unit is formatted according to 1) the first PHY mode or 2) the second PHY mode. Including stages.

  The step of analyzing the first preamble portion is to determine whether a plurality of signals of at least some pilot tones are flipped in response to 1) the first PHY mode or 2) the second PHY mode. Analyzing a plurality of signals of at least some pilot tones of the set.

  Analyzing the first preamble portion includes analyzing a field in the first preamble portion, wherein the field is formatted according to 1) the first PHY mode or 2) the second PHY mode. Contains information indicating

  A field including information indicating whether the PHY data unit is formatted according to the first PHY mode or the second PHY mode is 1) after the legacy part in the first preamble part, and 2) short training in the first preamble part. It is a signal field that occurs before the field.

  The second clock rate is lower than the first clock rate.

  The second clock rate is a fraction of the first clock rate.

  The second clock rate is 1/4 of the first clock rate.

  The second clock rate is faster than the first clock rate.

  The plurality of OFDM symbols in the OFDM portion have a first duration when the PHY data unit is formatted according to the first PHY mode, and the plurality of OFDM symbols in the OFDM portion are formatted according to the second PHY mode. A second duration when the second duration is different from the first duration.

  The second duration is longer than the first duration.

  A plurality of OFDM symbols in the OFDM part have a first tone interval when the PHY data unit is formatted according to the first PHY mode, and a plurality of OFDM symbols in the OFDM part are formatted according to the second PHY mode. A second tone interval, where the second tone interval is different from the first tone interval.

  The second tone interval is smaller than the first tone interval.

  In another embodiment, a communication device comprises a network interface having one or more integrated circuits, the one or more integrated circuits generating a first preamble portion of a PHY data unit according to a first clock rate. Where the PHY data unit is for transmission in accordance with a wireless communication protocol, the wireless communication protocol has a first PHY mode and a second PHY mode, and the first preamble portion is the first PHY data unit When transmitted according to the 1 PHY mode, it is formatted according to the first PHY mode, and the first preamble part is formatted according to the second PHY mode when the PHY data unit is transmitted according to the second PHY mode. The one or more integrated circuits are further configured to generate an OFDM portion of the PHY data unit, where the OFDM portion follows the first preamble portion and includes one or more long training fields. When the PHY data unit is transmitted according to the first PHY mode and is transmitted according to the first PHY mode, and the PHY data unit is transmitted according to the second PHY mode, the second PHY data unit is different from the first clock rate. Clocked at 2 clock rate.

  In other embodiments, the apparatus includes any suitable combination of one or more of the following features.

  The one or more integrated circuits are further configured to analyze the set of pilot tones in the first preamble portion to determine whether the PHY data unit is formatted according to 1) the first PHY mode or 2) the second PHY mode. Composed.

  The one or more integrated circuits may set a set of pilot tones to determine whether a plurality of signals of at least some pilot tones are flipped corresponding to 1) a first PHY mode or 2) a second PHY mode. Is further configured to analyze the plurality of signals of at least some of the pilot tones.

  The one or more integrated circuits are further configured to analyze a field in the first preamble portion, wherein the field is formatted according to 1) a first PHY mode or 2) a second PHY mode. Contains information indicating

  A field including information indicating whether the PHY data unit is formatted according to the first PHY mode or the second PHY mode is 1) after the legacy part in the first preamble part, and 2) short training in the first preamble part. It is a signal field that occurs before the field.

  The second clock rate is lower than the first clock rate.

  The second clock rate is a fraction of the first clock rate.

  The second clock rate is 1/4 of the first clock rate.

  The second clock rate is faster than the first clock rate.

  The multiple OFDM symbols in the OFDM part have a first duration when the PHY data unit is formatted according to the first PHY mode, and the multiple OFDM symbols in the OFDM part are formatted according to the second PHY mode. A second duration, where the second duration is different from the first duration.

  The second duration is longer than the first duration.

  A plurality of OFDM symbols in the OFDM part have a first tone interval when the PHY data unit is formatted according to the first PHY mode, and a plurality of OFDM symbols in the OFDM part are formatted according to the second PHY mode. A second tone interval, wherein the second tone interval is different from the first tone interval.

  The second tone interval is smaller than the first tone interval.

  At least some of the various blocks, operations, and techniques described above are hardware, a processor that executes multiple firmware instructions, a processor that executes multiple software instructions, or any combination thereof Can be implemented using. When implemented using a processor that executes multiple software or firmware instructions, the multiple software or firmware instructions may be stored on a magnetic disk, optical disk, or other storage medium, RAM or ROM or flash memory, processor, hard disk It can be stored in any computer readable memory, such as in a drive, optical disk drive, tape drive, etc. Similarly, a plurality of software or firmware instructions may be transmitted to a user or any desired or desired delivery method, including, for example, on a computer readable disk or other portable computer storage mechanism, or via a communication medium. Can be delivered to the system. Communication media typically embodies computer readable instructions, data structures, program modules or other data in a modulated data signal such as a carrier wave or other transport mechanism. The term “modulated data signal” means a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media includes wired media such as a wired network or direct-wired connection, and wireless media such as acoustic, radio frequency, infrared and other wireless media. Thus, a plurality of software or firmware instructions can be transmitted through a communication channel such as a telephone line, a DSL line, a cable TV line, an optical fiber line, a wireless communication channel, the Internet, etc. Can be delivered to the user or system via the same or compatible software offering). The plurality of software or firmware instructions may include machine-readable instructions that, when executed by the processor, cause the processor to perform various operations.

  When implemented in hardware, the hardware may include one or more discrete components, integrated circuits, application specific integrated circuits (ASICs), and the like.

While the invention has been described in connection with specific examples that are merely exemplary and not limiting of the invention, multiple changes, additions, and / or deletions are within the scope of the invention. It may be made to the disclosed embodiments without departing.
According to the present application, forms described in the following items are also disclosed.
[Item 1]
A method of generating a physical layer data unit (PHY data unit) for transmission according to a wireless communication protocol, wherein the wireless communication protocol has a first PHY mode and a second PHY mode,
Generating a first preamble part of the PHY data unit according to a first clock rate, the first preamble part being in accordance with the first PHY mode when the PHY data unit is transmitted according to the first PHY mode; The first preamble part is formatted according to the second PHY mode when the PHY data unit is transmitted according to the second PHY mode;
Generating an OFDM portion of the PHY data unit, the OFDM portion having a second preamble portion including one or more long training fields following the first preamble portion; Clocked at the first clock rate when the data unit is transmitted according to the first PHY mode, and clocked at a second clock rate different from the first clock rate when the PHY data unit is transmitted according to the second PHY mode. To be with the stage
With
Method.
[Item 2]
The step of generating the first preamble part includes generating a set of pilot tones in the first preamble part indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode. The method according to 1.
[Item 3]
Item 2 wherein, when the PHY data unit is transmitted according to the second PHY mode, a plurality of signals of at least some pilot tones in the set of pilot tones are flipped compared to the first PHY mode. The method described.
[Item 4]
The step of generating the first preamble portion includes the step of generating the first preamble portion having a field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode. 4. The method according to any one of items 1 to 3.
[Item 5]
The field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode is 1) after a legacy part in the first preamble part, and 2) the first preamble part. Item 5. The method of item 4, which is a signal field that occurs before the short training field in
[Item 6]
6. The method according to any one of items 1 to 5, wherein the second clock rate is lower than the first clock rate.
[Item 7]
7. The method of item 6, wherein the second clock rate is a fraction of the first clock rate.
[Item 8]
8. The method of item 7, wherein the second clock rate is 1/4 of the first clock rate.
[Item 9]
6. The method according to any one of items 1 to 5, wherein the second clock rate is faster than the first clock rate.
[Item 10]
When the OFDM part is generated, and thus the PHY data unit is transmitted according to the first PHY mode, a plurality of OFDM symbols in the OFDM part have a first duration, and the PHY data unit is the first PHY data unit. The item according to any one of items 1 to 9, wherein when transmitted according to a 2PHY mode, a plurality of OFDM symbols in the OFDM section have a second duration, and the second duration is different from the first duration. The method described in 1.
[Item 11]
Item 11. The method of item 10, wherein the second duration is longer than the first duration.
[Item 12]
When the OFDM unit is generated, and thus the PHY data unit is transmitted according to the first PHY mode, a plurality of OFDM symbols in the OFDM unit have a first tone interval, and the PHY data unit is the first PHY data unit. The item according to any one of items 1 to 11, wherein when transmitted according to a 2PHY mode, a plurality of OFDM symbols in the OFDM section have a second tone interval, and the second tone interval is different from the first tone interval. The method described in 1.
[Item 13]
13. The method of item 12, wherein the second tone interval is less than the first tone interval.
[Item 14]
A communication device comprising a network interface having one or more integrated circuits,
The one or more integrated circuits are:
Generating a first preamble portion of a physical layer data unit for transmission (PHY data unit) according to a wireless communication protocol having a first PHY mode and a second PHY mode according to a first clock rate;
Generating an OFDM portion of the PHY data unit;
The first preamble part is formatted according to the first PHY mode when the PHY data unit is transmitted according to the first PHY mode;
The first preamble part is formatted according to the second PHY mode when the PHY data unit is transmitted according to the second PHY mode;
The OFDM part is
Following the first preamble part,
Having a second preamble portion including one or more long training fields;
Clocked at the first clock rate when the PHY data unit is transmitted according to a first PHY mode;
Clocked at a second clock rate different from the first clock rate when the PHY data unit is transmitted according to a second PHY mode;
Communication device.
[Item 15]
15. The item (14), wherein the one or more integrated circuits generate a set of pilot tones in the first preamble portion indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode. Communication devices.
[Item 16]
Item 15. The plurality of signals of at least some pilot tones in the set of pilot tones are flipped when compared to the first PHY mode when the PHY data unit is transmitted according to the second PHY mode. The communication device described.
[Item 17]
Items 14 to 16 wherein the one or more integrated circuits generate the first preamble portion having a field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode. The communication device according to any one of the above.
[Item 18]
The field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode is 1) after a legacy part in the first preamble part, and 2) the first preamble part. Item 18. The communication device of item 17, wherein the communication device is a signal field that occurs before the short training field.
[Item 19]
The communication device according to any one of items 14 to 18, wherein the second clock rate is lower than the first clock rate.
[Item 20]
20. The communication device according to item 19, wherein the second clock rate is a fraction of the first clock rate.
[Item 21]
Item 21. The communication device according to Item 20, wherein the second clock rate is 1/4 of the first clock rate.
[Item 22]
20. The communication device according to any one of items 14 to 19, wherein the second clock rate is faster than the first clock rate.
[Item 23]
The one or more integrated circuits generate the OFDM part, so that when the PHY data unit is transmitted according to the first PHY mode, a plurality of OFDM symbols in the OFDM part have a first duration. And a plurality of OFDM symbols in the OFDM unit have a second duration when the PHY data unit is transmitted according to the second PHY mode, and the second duration is different from the first duration The communication device according to any one of Items 14 to 22.
[Item 24]
24. The communication device of item 23, wherein the second duration is longer than the first duration.
[Item 25]
The one or more integrated circuits generate the OFDM part, so that when the PHY data unit is transmitted according to the first PHY mode, a plurality of OFDM symbols in the OFDM part have a first tone interval. And when the PHY data unit is transmitted according to the second PHY mode, a plurality of OFDM symbols in the OFDM unit have a second tone interval, and the second tone interval is different from the first tone interval. 25. The communication device according to any one of items 14 to 24.
[Item 26]
26. The communication device of item 25, wherein the second tone interval is smaller than the first tone interval.

Claims (22)

A method of generating a physical layer data unit (PHY data unit) for transmission according to a wireless communication protocol, wherein the wireless communication protocol has a first PHY mode and a second PHY mode,
Generating a first preamble part of the PHY data unit according to a first clock rate, the first preamble part including a legacy part and a high-efficiency WLAN signal (HEW-SIGA) field, wherein the legacy part comprises: A legacy short training field (L-STF), a legacy long training field (L-LTF), and a legacy signal (L-SIG) field, wherein the first preamble portion is a PHY data unit Formatting the second preamble part and the data part to indicate whether the first clock rate or a second clock rate lower than the first clock rate is clocked ;
Wherein a step of generating the second preamble portion and the data portion of the PHY data unit, the second preamble section and the data section is followed by the first preamble portion, the second preamble section, one or more efficient WLAN long training field (HEW-LTF) seen including, the second preamble part and the data part, if the PHY data unit is transmitted in accordance with the first 1PHY mode, the first Clocked at a second clock rate that is lower than the first clock rate when clocked at a clock rate and the PHY data unit is transmitted according to the second PHY mode.   Generating the first preamble portion includes generating a set of pilot tones in the first preamble portion indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode. Item 2. The method according to Item 1.   The plurality of signals of at least some pilot tones in the set of pilot tones are flipped when compared to the first PHY mode when the PHY data unit is transmitted according to the second PHY mode. The method described in 1.   The step of generating the first preamble portion includes the step of generating the first preamble portion having a field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode. 4. The method according to any one of claims 1 to 3.   The field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode is 1) after a legacy part in the first preamble part, and 2) the first preamble part. The method of claim 4, wherein the signal field occurs before the short training field at. The method according to any one of claims 1 to 5, wherein the second clock rate is a fraction of the first clock rate. The method of claim 6 , wherein the second clock rate is 1/2, 1/4 , 1/10, or 1/16 of the first clock rate. The second preamble part and the data part are generated, whereby when the PHY data unit is transmitted according to the first PHY mode, a plurality of OFDM symbols in the second preamble part and the data part are first sustained. When the PHY data unit is transmitted according to the second PHY mode, a plurality of OFDM symbols in the second preamble part and the data part have a second duration, and the second duration is the first duration is different, the method according to any one of claims 1 to 7. The method of claim 8 , wherein the second duration is longer than the first duration. When the second preamble part and the data part are generated so that the PHY data unit is transmitted according to the first PHY mode, a plurality of OFDM symbols in the second preamble part and the data part are first tones. When the PHY data unit is transmitted according to the second PHY mode, a plurality of OFDM symbols in the second preamble part and the data part have a second tone interval, and the second tone interval is 10. The method according to any one of claims 1 to 9 , wherein the method is different from the first tone interval. The method of claim 10 , wherein the second tone interval is less than the first tone interval. A communication device comprising a network interface having one or more integrated circuits,
The one or more integrated circuits are:
Generating a first preamble portion of a physical layer data unit for transmission (PHY data unit) according to a wireless communication protocol having a first PHY mode and a second PHY mode according to a first clock rate;
Generating a second preamble portion and a data portion of the PHY data unit;
The first preamble part includes a legacy part and a high efficiency WLAN signal (HEW-SIGA) field ;
The first preamble portion is formatted to indicate whether the second preamble portion and the data portion of the PHY data unit are clocked at a first clock rate or a second clock rate lower than the first clock rate. And
The second preamble part and the data part follow the first preamble part,
It said second preamble section, viewed contains one or more high efficiency WLAN long training field (HEW-LTF),
Said second preamble section and the data section, the PHY data unit, when it is transmitted in accordance with the first 1PHY mode, clocked at the first clock rate,
Said second preamble section and the data section, wherein when the PHY data unit is transmitted in accordance with the first 2PHY mode is clocked at a lower than the first clock rate said second clock rate,
Communication device. Said one or more integrated circuits indicates whether the PHY data unit is generated according to the first 1PHY mode or said second 2PHY mode, to generate a set of pilot tones in said first preamble portion, to claim 12 The communication device described. Wherein when the PHY data unit is transmitted in accordance with the first 2PHY mode, as compared with the first 1PHY mode, a plurality of signals of at least some of the pilot tones in said set of pilot tones is flip claim 13 The communication device described in 1. Said one or more integrated circuit generates the first preamble section having a field containing information indicating whether the PHY data unit is generated according to the first 1PHY mode or said second 2PHY mode, claim 12 The communication device according to any one of 14 . The field including information indicating whether the PHY data unit is generated according to the first PHY mode or the second PHY mode is 1) after a legacy part in the first preamble part, and 2) the first preamble part. The communication device of claim 15 , wherein the communication device is a signal field that occurs before the short training field at. The communication device according to claim 12 , wherein the second clock rate is a fraction of the first clock rate. The communication device according to claim 17 , wherein the second clock rate is ½, ¼ , 1/10, or 1/16 of the first clock rate. The one or more integrated circuits generate the second preamble part and the data part , whereby when the PHY data unit is transmitted according to the first PHY mode, the second preamble part and the data When a plurality of OFDM symbols in the unit have a first duration and the PHY data unit is transmitted according to the second PHY mode, the plurality of OFDM symbols in the second preamble unit and the data unit have a second duration. The communication device according to any one of claims 12 to 18 , wherein the second duration is different from the first duration. The communication device of claim 19 , wherein the second duration is longer than the first duration. The one or more integrated circuits generate the second preamble part and the data part , whereby when the PHY data unit is transmitted according to the first PHY mode, the second preamble part and the data A plurality of OFDM symbols in the second preamble part and the data part have a second tone interval when a plurality of OFDM symbols in the part have a first tone interval and the PHY data unit is transmitted according to the second PHY mode. 21. The communication device according to any one of claims 12 to 20 , wherein the second tone interval is different from the first tone interval. The communication device according to claim 21 , wherein the second tone interval is smaller than the first tone interval.

Images