Midamble format for packets in vehicular communication networks

Abstract

In a vehicle communication network, a communication device generates a PHY preamble of a physical layer (PHY) protocol data unit (PPDU) for transmission in the vehicle communication network. The communication device generates a plurality of PHY data segments of the PPDU, and one or more PHY midambles, each of which is to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble includes one or more training signal fields. Generating one or more PHY midambles includes: when the PPDU is to be transmitted according to an extended range (ER) mode, generating each training signal field to include i) a first part based on a very high throughput long training field (VHT-LTF) defined by the IEEE802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard; and transmitting the PPDU in the vehicle communication network by the communication device.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 897,130, filed on September 6, 2019, and entitled “Next-Generation Vehicular (NGV) Midamble Format,” which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to vehicle communication networks and, more particularly, to physical layer protocol data unit formats. Background Art

[0004] Wireless local area networks (WLANs) have grown rapidly over the past decade, and the development of WLAN standards such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards has increased 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 802.11g standards specify a single-user peak throughput of 54 Mbps, the IEEE 802.11n standard specifies a single-user peak throughput of 600 Mbps, and the IEEE 802.11ac standard specifies a single-user peak throughput in the gigabits per second (Gbps) range. Future standards promise to provide even greater throughput, such as throughput in the tens of Gbps range.

[0005] The IEEE 802.11p standard specifies a protocol for Wireless Access in Vehicular Environments (WAVE). Future WAVE standards, such as the IEEE 802.11bd standard (currently under development), are intended to provide improved vehicle-to-vehicle or vehicle-to-infrastructure connectivity, throughput, infotainment features, etc. Some challenges encountered in vehicular communication networks are caused by the relatively fast movement of transmitters and receivers. For example, when the transmitter and / or receiver are moving relative to each other at high speeds, channel conditions may change significantly during the transmission of a packet. Summary of the invention

[0006] In one embodiment, a method for wireless communication in a vehicle communication network includes: generating a physical layer (PHY) protocol data unit (PPDU) for transmission in the vehicle communication network at a communication device according to a communication protocol for vehicle communication; generating multiple PHY data segments of the PPDU at the communication device; generating one or more PHY midambles at the communication device, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble includes one or more training signal fields, wherein generating the one or more PHY midambles includes: when the PPDU is to be transmitted according to an extended range (ER) mode defined by the communication protocol, generating each training signal field to include i) a first part based on a very high throughput long training field (VHT-LTF) defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard; and transmitting the PPDU in the vehicle communication network by the communication device.

[0007] In another embodiment, a communication device is configured to operate in a vehicle communication network and includes a wireless network interface device. The wireless network interface device includes one or more IC devices, which are configured to: generate a PHY preamble code for a PPDU transmitted in the vehicle communication network according to a communication protocol for vehicle communication; generate multiple PHY data segments of the PPDU; generate one or more PHY midambles, each PHY midamble is to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble includes one or more training signal fields, wherein generating the one or more PHY midambles includes: when the PPDU is to be transmitted according to an extended range (ER) mode defined by the communication protocol, generating each training signal field to include i) a first part based on a VHT-LTF defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard; and control the wireless network interface device to transmit the PPDU in the vehicle communication network.

[0008] In yet another embodiment, a method for accessing a communication channel in a vehicle communication network includes: generating, at a communication device, a PHY preamble of a PPDU for transmission in the vehicle communication network according to a communication protocol for vehicle communication; generating, at the communication device, a plurality of PHY data segments of the PPDU; selecting, at the communication device, one or more PHY midamble formats from a set of a plurality of different PHY midamble formats based on a transmission mode of the PPDU, wherein the set of a plurality of different PHY midamble formats includes i) a first format corresponding to an extended range transmission mode defined by the communication protocol, the first format using an uncompressed training signal field, and ii) A second format corresponding to a high throughput transmission mode defined by a communication protocol, the second format using a compressed training signal field; generating one or more PHY midambles at a communication device according to the selected format, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble including one or more training signal fields, wherein generating each PHY midamble includes: i) selectively including an uncompressed training signal field when the first format is selected, and ii) selectively including a compressed training signal field when the second format is selected; and transmitting the PPDU by the communication device in a vehicle communication network.

[0009] In yet another embodiment, a communication device is configured to operate in a vehicle communication network and includes a wireless network interface device. The wireless network interface device includes one or more IC devices, which are configured to: generate a PHY preamble code for a PPDU for transmission in a vehicle communication network according to a communication protocol for vehicle communication; generate multiple PHY data segments of the PPDU; select one or more PHY midamble formats from a group of multiple different PHY midamble formats based on the transmission mode of the PPDU, wherein the group of multiple different PHY midamble formats includes i) a first format corresponding to an extended range transmission mode defined by the communication protocol, the first format uses an uncompressed training signal field, and ii) a second format corresponding to a high throughput transmission mode defined by the communication protocol, the second format uses a compressed training signal field; generate one or more PHY midambles according to the selected format, each PHY midamble is transmitted between a corresponding pair of adjacent PHY data segments, each PHY midamble includes one or more training signal fields, wherein generating each PHY midamble includes: i) when the first format is selected, selectively including an uncompressed training signal field, and ii) when the second format is selected, selectively including a compressed training signal field; and control the wireless network interface device to transmit the PPDU in the vehicle communication network. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a block diagram of an example vehicle communication network according to an embodiment.

[0011] Figure 2A According to an embodiment, Figure 1 Schematic diagram of an example physical layer protocol data unit (PPDU) transmitted in a vehicle communication network.

[0012] Figure 2B According to an embodiment, Figure 1 Schematic diagram of another example PPDU transmitted in a vehicle communication network.

[0013] Figure 3 According to the embodiment, Figure 2A and Figure 2B Block diagram of an example physical layer (PHY) midamble used in conjunction with a PPDU.

[0014] Figure 4 According to another embodiment, Figure 2A and Figure 2B FIG. 1 is a block diagram of another example PHY midamble for use with a PPDU.

[0015] Figure 5 According to another embodiment, Figure 2A and Figure 2B FIG. 1 is a block diagram of another example PHY midamble for use with a PPDU.

[0016] Figure 6 According to an embodiment, Figure 1 Flowchart of an example method for transmitting a PPDU in a vehicle communication network.

[0017] Figure 7 According to another embodiment, Figure 1 Flowchart of an example method for transmitting a PPDU in a vehicle communication network.

[0018] Figure 8 According to another embodiment, Figure 1 Flowchart of another example method for transmitting a PPDU in a vehicle communication network.

[0019] Fig. 9 According to another embodiment, Figure 1 Flowchart of another example method for transmitting a PPDU in a vehicle communication network. DETAILED DESCRIPTION

[0020] In the embodiments described below, a vehicle communication network includes communication devices, such as access points and client stations, operating according to one or more protocols that define Wireless Access in Vehicular Environments (WAVE) communications. In one embodiment, the access point is embedded in a roadside unit and the client station is embedded in a mobile vehicle operating in the vehicle communication network. In one embodiment, the client station operating in the vehicle communication network communicates with other client stations and / or roadside units to exchange information, such as safety warnings, traffic information, etc., that can enhance the safety of the mobile vehicle, improve the driving experience of the mobile vehicle, etc. In order to improve performance in the vehicle communication network (e.g., mitigate the Doppler effect), packets transmitted in the vehicle communication network are generated to include a physical layer (PHY) midamble that allows a receiver to update a channel estimate during packet reception. Various example PHY midamble formats are described below.

[0021] Figure 1 1 is a block diagram of an example vehicle communication network 110 according to an embodiment. The vehicle communication network 110 includes an access point (AP) 114. In one embodiment, the AP 114 corresponds to a roadside unit operating in the vehicle communication network. The AP 114 includes a host processor 118 coupled to a network interface device 122. In one embodiment, the network interface device 122 includes a media access control (MAC) processor 126 and a PHY processor 130. The PHY processor 130 includes a plurality of transceivers 134, and the transceivers 134 are coupled to a plurality of antennas 138. Although in Figure 1 134 and three antennas 138 are shown, but in other embodiments, the AP 114 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers 134 and antennas 138. In some embodiments, the AP 114 includes a greater number of antennas 138 than the transceivers 134, and antenna switching techniques are utilized. In one embodiment, the MAC processor 126 and the PHY processor 130 are configured to operate according to at least a first communication protocol (e.g., the IEEE 802.11bd standard or another suitable communication protocol designed for vehicle communication). In another embodiment, the MAC processor 126 and the PHY processor 130 are also configured to operate according to a second communication protocol different from the first communication protocol (e.g., the IEEE 802.11p standard or another suitable communication protocol designed for vehicle communication). In some embodiments, the second communication protocol is a conventional communication protocol with respect to the first communication protocol.

[0022] The network interface device 122 is implemented using one or more integrated circuits (ICs) configured to operate as described below. For example, the MAC processor 126 may be implemented at least in part on a first IC, and the PHY processor 130 may be implemented at least in part on a second IC. As another example, at least a portion of the MAC processor 126 and at least a portion of the PHY processor 130 may be implemented on a single IC. For example, the network interface device 122 may be implemented using a system on chip (SoC), wherein the SoC includes at least a portion of the MAC processor 126 and at least a portion of the PHY processor 130. As yet another example, the entire MAC processor 126 and the entire PHY processor 130 may be implemented on a single IC.

[0023] In one embodiment, the host processor 118 includes a processor configured to execute machine-readable instructions stored in a memory device (not shown), such as a random access memory (RAM), a read-only memory (ROM), a flash memory, etc. In one embodiment, the host processor 118 can be implemented at least in part on a first IC, and the network interface device 122 can be implemented at least in part on a second IC. As another example, the host processor 118 and at least a portion of the network interface device 122 can be implemented on a single IC.

[0024] In various embodiments, the MAC processor 126 and / or the PHY processor 130 of the AP 114 are configured to generate data units conforming to the first communication protocol and process received data units conforming to the first communication protocol. For example, the MAC processor 126 is configured to implement MAC layer functions, including MAC layer functions of the first communication protocol, and the PHY processor 130 is configured to implement PHY functions, including PHY functions of the first communication protocol. For example, the MAC processor 126 is configured to generate MAC layer data units, such as MAC service data units (MSDUs), MPDUs, A-MPDUs, etc., and provide the MAC layer data units to the PHY processor 130.

[0025] The PHY processor 130 is configured to receive MAC layer data units from the MAC processor 126 and encapsulate the MAC layer data units to generate PHY data units, such as PHY protocol data units (PPDUs), PHY protocol service data units (PSDUs), etc., for transmission via the antenna 138. Similarly, the PHY processor 130 is configured to receive PHY data units received via the antenna 138 and extract the MAC layer data units encapsulated within the PHY data units. The PHY processor 130 may provide the extracted MAC layer data units to the MAC processor 126, which processes the MAC layer data units.

[0026] According to one embodiment, the PHY processor 130 is configured to down-convert one or more radio frequency (RF) signals received via one or more antennas 138 into one or more baseband analog signals and convert the analog baseband signal(s) into one or more digital baseband signals. The PHY processor 130 is also configured to process the one or more digital baseband signals to demodulate the one or more digital baseband signals and generate a PPDU. The PHY processor 130 includes one or more forward error correction (FEC) encoders (e.g., binary convolutional code (BCC) encoders, low-density parity check (LDPC) encoders, etc.), one or more FEC decoders (e.g., BCC decoders, LDPC decoders, etc.), amplifiers (e.g., low noise amplifiers (LNAs), power amplifiers, etc.), radio frequency (RF) downconverters, RF upconverters, multiple filters, one or more analog-to-digital converters (ADCs), one or more digital-to-analog converters (DACs), one or more discrete Fourier transform (DFT) calculators (e.g., fast Fourier transform (FFT) calculators), one or more inverse discrete Fourier transform (IDFT) calculators (e.g., inverse fast Fourier transform (IFFT) calculators), one or more modulators, one or more demodulators, etc.

[0027] The PHY processor 130 is configured to generate one or more RF signals, which are provided to the one or more antennas 138. The PHY processor 130 is also configured to receive one or more RF signals from the one or more antennas 138.

[0028] According to some embodiments, the MAC processor 126 is configured to control the PHY processor 130 to generate one or more RF signals, for example, by providing one or more MAC layer data units (e.g., MPDUs) to the PHY processor 130 and optionally providing one or more control signals to the PHY processor 130. In one embodiment, the MAC processor 126 includes a processor configured to execute machine-readable instructions stored in a memory device (not shown), such as a RAM, ROM, flash memory, etc. In one embodiment, the MAC processor 126 includes a hardware state machine configured to perform MAC layer functions, control the PHY processor 130, etc.

[0029] In some embodiments, the first communication protocol defines a plurality of transmission modes, and the PHY processor 130 is configured to generate a PPDU having a format and / or content that varies for different transmission modes. As an example, the plurality of transmission modes include an extended range (ER) mode and one or more non-ER modes. According to one embodiment, the ER mode is designed to increase the range in which the receiver can correctly decode the PPDU. For example, the ER mode employs a modulation technique and / or coding technique that utilizes increased redundancy at the expense of data throughput. In another embodiment, the plurality of transmission modes additionally or alternatively include a high throughput mode, which may use a more complex modulation technique that increases throughput but reduces the range in which the PPDU can be correctly decoded. In another embodiment, the plurality of transmission modes include i) an ER mode as discussed above, ii) a high throughput mode as discussed above, and iii) a default transmission mode. According to one embodiment, the default mode is generally designed to provide a reception range that tends to fall between the reception range of the ER mode and the reception range of the high throughput mode, and is generally designed to provide a data throughput that tends to fall between the data throughput of the ER mode and the data throughput of the high throughput mode.

[0030] In one embodiment, the network interface device 122 includes (e.g., the PHY processor 130 includes) a PHY midamble generator 142, which is configured to generate a PHY midamble based on a very high throughput long training field (VHT-LTF) defined by the IEEE 802.11ac standard. In some embodiments, the PHY midamble generator 142 is configured to generate one or more PHY midambles for the PPDU to have different contents according to the transmission mode of the PPDU. According to various embodiments, the PHY midamble generator 142 is configured to generate one or more PHY midambles, which have the format described below or have other suitable PHY midamble formats.

[0031] In one embodiment, the PHY midamble generator 142 includes a hardware circuit system configured to generate a PHY midamble as described below or other suitable PHY midambles. In one embodiment, in various embodiments, the PHY midamble generator 142 is additionally or alternatively implemented by a processor configured to execute machine-readable instructions stored in a memory device (not shown) such as a RAM, ROM, flash memory, etc.

[0032] The vehicle communication network 110 includes a plurality of client stations 154. According to one embodiment, each client station 154 is included in a corresponding vehicle. For example, according to an illustrative embodiment, the AP 114 is located along a road, and the plurality of client stations 154 are in vehicles traveling on the road. Figure 1 Three client stations 154 are shown in FIG. 1 , but in various embodiments, the vehicle communication network 110 includes other suitable numbers (eg, 1, 2, 4, 5, 6, etc.) of client stations 154 .

[0033] The client station 154-1 includes a host processor 158 coupled to a network interface device 162. The network interface device 162 includes a MAC processor 166 and a PHY processor 170. The PHY processor 170 includes a plurality of transceivers 174, and the transceivers 174 are coupled to a plurality of antennas 178. Figure 1 174 and three antennas 178 are shown, but in other embodiments, the client station 154-1 includes other suitable numbers (e.g., 1, 2, 4, 5, etc.) of transceivers 174 and antennas 178. In some embodiments, the client station 154-1 includes a greater number of antennas 178 than transceivers 174, and antenna switching techniques are utilized. In various embodiments, the MAC processor 126 and the PHY processor 130 are configured to operate according to at least a first communication protocol (e.g., the IEEE 802.11bd standard) and / or a second communication protocol (e.g., the IEEE 802.11p standard).

[0034] The network interface device 162 is implemented using one or more ICs configured to operate as described below. For example, the MAC processor 166 can be implemented on at least a first IC, and the PHY processor 170 can be implemented on at least a second IC. As another example, at least a portion of the MAC processor 166 and at least a portion of the PHY processor 170 can be implemented on a single IC. For example, the network interface device 162 can be implemented using a SoC, wherein the SoC includes at least a portion of the MAC processor 166 and at least a portion of the PHY processor 170. As yet another example, the entire MAC processor 166 and the entire PHY processor 170 can be implemented on a single IC.

[0035] In one embodiment, the host processor 158 includes a processor configured to execute machine-readable instructions stored in a memory device (not shown) such as RAM, ROM, flash memory, etc. In one embodiment, the host processor network interface device 158 can be implemented at least in part on a first IC, and the network interface device 162 can be implemented at least in part on a second IC. As another example, the host processor 158 and at least a portion of the network interface device 162 can be implemented on a single IC.

[0036] In various embodiments, the MAC processor 166 and the PHY processor 170 of the client station 154-1 are configured to generate data units conforming to the first communication protocol or another suitable communication protocol and process received data units conforming to the first communication protocol or another suitable communication protocol. For example, the MAC processor 166 is configured to implement MAC layer functions, including MAC layer functions of the first communication protocol, and the PHY processor 170 is configured to implement PHY functions, including PHY functions of the first communication protocol. For example, the MAC processor 166 is configured to generate MAC layer data units, such as MAC service data units (MSDUs), MPDUs, A-MPDUs, etc., and provide the MAC layer data units to the PHY processor 170.

[0037] The PHY processor 170 is configured to receive MAC layer data units from the MAC processor 166 and encapsulate the MAC layer data units to generate PHY data units, such as PHY protocol data units (PPDUs), PHY protocol service data units (PSDUs), etc., for transmission via the antenna 174. Similarly, the PHY processor 170 is configured to receive PHY data units received via the antenna 174 and extract the MAC layer data units encapsulated within the PHY data units. The PHY processor 170 may provide the extracted MAC layer data units to the MAC processor 166, which processes the MAC layer data units.

[0038] According to one embodiment, the PHY processor 170 is configured to down-convert one or more radio frequency (RF) signals received via one or more antennas 174 into one or more baseband analog signals, and convert the analog baseband signal(s) into one or more digital baseband signals. The PHY processor 170 is also configured to process the one or more digital baseband signals to demodulate the one or more digital baseband signals and generate a PPDU. The PHY processor 170 includes one or more forward error correction (FEC) encoders (e.g., binary convolutional code (BCC) encoders, low-density parity check (LDPC) encoders, etc.), one or more FEC decoders (e.g., BCC decoders, LDPC decoders, etc.), amplifiers (e.g., low noise amplifiers (LNAs), power amplifiers, etc.), radio frequency (RF) downconverters, RF upconverters, multiple filters, one or more analog-to-digital converters (ADCs), one or more digital-to-analog converters (DACs), one or more discrete Fourier transform (DFT) calculators (e.g., fast Fourier transform (FFT) calculators), one or more inverse discrete Fourier transform (IDFT) calculators (e.g., inverse fast Fourier transform (IFFT) calculators), one or more modulators, one or more demodulators, etc.

[0039] The PHY processor 170 is configured to generate one or more RF signals, which are provided to the one or more antennas 178. The PHY processor 170 is also configured to receive one or more RF signals from the one or more antennas 178.

[0040] According to some embodiments, the MAC processor 166 is configured to control the PHY processor 170 to generate one or more RF signals, for example, by providing one or more MAC layer data units (e.g., MPDUs) to the PHY processor 170, and optionally providing one or more control signals to the PHY processor 170. In one embodiment, the MAC processor 166 includes a processor configured to execute machine-readable instructions stored in a memory device (not shown), such as a RAM, ROM, flash memory, etc. In one embodiment, the MAC processor 166 includes a hardware state machine configured to perform MAC layer functions, control the PHY processor 170, etc.

[0041] In some embodiments, the PHY processor 170 is configured to generate a PPDU having a format and / or content that varies for different transmission modes defined by the first communication protocol, similar to the PHY processor 130 described above.

[0042] In one embodiment, the network interface device 162 includes (e.g., the PHY processor 170 includes) a PHY midamble generator 192, which is configured to generate a PHY midamble based on the VHT-LTF defined by the IEEE 802.11ac standard. In some embodiments, the PHY midamble generator 192 is configured to generate one or more PHY midambles for the PPDU according to the transmission mode of the PPDU so that it has different content. According to various embodiments, the PHY midamble generator 192 is configured to generate one or more PHY midambles, and the one or more PHY midambles have the format described below or have other suitable PHY midamble formats.

[0043] In one embodiment, the PHY midamble generator 192 includes a hardware circuit system configured to generate a PHY midamble as described below or other suitable PHY midambles. In one embodiment, in various embodiments, the PHY midamble generator 192 is additionally or alternatively implemented by a processor configured to execute machine-readable instructions stored in a memory device (not shown) such as a RAM, ROM, flash memory, etc.

[0044] although Figure 1Communications between AP 114 and respective client stations 154 are depicted, but according to some embodiments, two or more client stations 154 communicate directly with each other. For example, according to some embodiments, vehicle communication network 110 allows direct client-to-client communications that are not routed through AP 114.

[0045] In one embodiment, each of client stations 154-2 and 154-3 has the same or similar structure as client station 154-1. Each of client stations 154-2 and 154-3 has the same or different number of transceivers and antennas. For example, according to one embodiment, client station 154-2 and / or client station 154-3 each has only two transceivers and two antennas (not shown).

[0046] Figure 2A According to an embodiment, a method for transmitting data in a vehicle communication network such as a vehicle communication network 110 ( Figure 1 ) is a diagram of an example PPDU 200 transmitted in a vehicle communication network. According to one embodiment, the network interface device 122 ( Figure 1 ) is configured to generate a PPDU (such as PPDU 200) and transmit it to one or more client stations 154. In one embodiment, the network interface device 162 ( Figure 1 ) is also configured to generate a PPDU, such as PPDU 200, and transmit it to the AP 114 or another client station 154. In one embodiment, the PHY processor 130 / 170 is configured to generate a PPDU, such as PPDU 200. In one embodiment, the PHY processor 130 / 170 is configured to receive and process a PPDU, such as PPDU 200.

[0047] According to one embodiment, the PPDU 200 complies with a first communication protocol (e.g., the IEEE 802.11bd standard). In various embodiments, the PPDU 200 spans a suitable bandwidth, such as 10 MHz, 20 MHz. In other embodiments, a PPDU similar to the PPDU 200 occupies a different bandwidth, such as 5 MHz, 40 MHz, or any suitable bandwidth. The PPDU is suitable for "mixed mode" situations, that is, when the vehicle communication network 100 includes a client station (i.e., a legacy client station 154-4) that complies with a traditional communication protocol (e.g., the IEEE 802.11p standard), but does not comply with the first communication protocol (e.g., the IEEE 802.11bd standard). The data unit 200 may also be used in other situations.

[0048] The PPDU 200 includes a PHY preamble 204 and a PHY data portion 208. According to one embodiment, the PHY preamble 204 includes a legacy PHY preamble portion 212 that conforms to the second communication protocol. In one embodiment, the legacy PHY preamble portion 212 includes a legacy short training field (LSTF) 216 that is typically used for packet detection, initial synchronization, and automatic gain control (AGC) adjustment, and a legacy long training field (LLTF) 212 that is typically used for channel estimation and fine synchronization. The legacy PHY preamble portion 212 also includes a legacy signal field (LSIG) 224. In one embodiment, the LSIG 224 includes a signal field defined by the second communication protocol and includes information about the PPDU 200, such as the duration of the PPDU 200. For example, in one embodiment, the LSIG 224 includes a rate subfield (not shown) and a length subfield (not shown) that together indicate the duration of the PPDU 200. In some embodiments, the duration information in the LSIG 224 allows client stations and / or APs (e.g., legacy communication devices) that conform to the second communication protocol but not the first communication protocol to determine the duration of the PPDU 200. In some embodiments, such devices will refrain from transmitting until after the transmission of the PPDU 200 is complete and therefore will not interfere with the transmission of the PPDU 200.

[0049] In some embodiments, the PHY preamble 204 includes a repetition of the LSIG 224, referred to as a repeated LSIG (RL-SIG) 228. The RL-SIG 228 provides redundancy for the LSIG 224 and, therefore, improves decoding of the LSIG 224 at the receiver. In some embodiments, the first communication protocol defines a plurality of transmission modes, including an ER mode and one or more non-ER modes (such as one or both of a high throughput mode and a default mode), and the RL-SIG 228 is included in the PPDU 200 only when the PPDU 200 conforms to the ER mode. In other embodiments, the RL-SIG 228 is also included for one or more non-ER modes defined by the first communication protocol. In some embodiments, the RL-SIG 228 is included for all transmission modes defined by the first communication protocol.

[0050] The PHY preamble 204 also includes a signal field 232 that conforms to the first communication protocol. In one embodiment, the signal field 232 is sometimes referred to as a Next Generation Vehicle (NGV) signal field (NGV-SIG) 232. The NGV-SIG 232 conforms to the first communication protocol and is decodable by a communication device configured to operate according to the first communication protocol. In one embodiment, the NGV-SIG 232 includes one or more subfields indicating PHY parameters corresponding to the PHY data portion 208, such as a modulation coding scheme (MCS) subfield indicating the MCS used to encode the data portion 220, a dual subcarrier feature (e.g., DCM) subfield indicating whether a suitable parameter (e.g., carrier spacing) is enabled, and a dual subcarrier modulation (DCM) subfield, etc. In some embodiments, the NGV-SIG 232 includes a subfield indicating a PHY midamble period of the PHY data portion 208. In one embodiment, the PHY midamble period indicates the number of orthogonal frequency division multiplexing (OFDM) symbols between adjacent PHY midambles in the PHY data portion 208.

[0051] In some embodiments, the PHY preamble 204 includes a repetition of the NGV-SIG 232, referred to as a repeated NGV-SIG (RNGV-SIG) 236. For example, a copy of all bits of the NGV-SIG 232 is included in the RNGV-SIG 236. The RNGV-SIG 236 provides redundancy for the NGV-SIG 232 and thus improves decoding of the NGV-SIG 232 at the receiver. In some embodiments, the first communication protocol defines a plurality of transmission modes, including an ER mode and one or more non-ER modes, and the RNGV-SIG 236 is included in the PPDU 200 only when the PPDU 200 conforms to the ER mode. In other embodiments, the RNGV-SIG 236 is also included for one or more non-ER modes defined by the first communication protocol. In some embodiments, the RNGV-SIG 236 is included for all transmission modes defined by the first communication protocol.

[0052] The PHY preamble 204 also includes a NGV short training field (NGV-STF) 240. In some embodiments, the NGV-STF 240 is used by the receiver for synchronization and AGC adjustment. In addition, the PHY preamble 204 includes one or more NGV long training fields (NGVLTF) 244. In some embodiments, one or more NGV-LTFs 244 are used by the receiver for channel estimation. In one embodiment, the number of NGV-LTFs 244 corresponds to the number of spatial streams via which the PPDU 200 is transmitted. As an illustrative example, when the PPDU 200 is to be transmitted via one spatial stream, only one NGV-LTF 244 is included, and when the PPDU 200 is to be transmitted via two spatial streams, two NGV-LTFs 244 are included.

[0053] According to one embodiment, the PHY data portion 208 includes a plurality (e.g., a positive integer i greater than 1) of PHY data segments 252 and one or more PHY midambles 256. In one embodiment, the PHY data segments 252-1 to 252-(i-1) include M OFDM symbols, where M is a suitable positive integer. In one embodiment, each PHY midamble includes one or more training signal fields, as described below.

[0054] In one embodiment, the PHY preamble 204 includes a plurality of OFDM symbols, and each field of the PHY preamble 204 (such as Figure 2AIn one embodiment, a portion of the PHY preamble 204 (e.g., the legacy PHY preamble 212, the RL-SIG 228 (if included), the NGV-SIG 232, and the RNGV-SIG 236 (if included)) is generated based on OFDM numerology defined by a third wireless communication standard for a bandwidth greater than the bandwidth of the PPDU 200 and the portion of the PHY preamble 204 is generated using a downclocking factor to span the narrower bandwidth of the PPDU 200. For example, the portion of the PHY preamble 204 is generated based on OFDM numerology defined by the IEEE 802.11a standard for a 20 MHz bandwidth and the PHY preamble 202 is generated using a downclocking factor of two (x2) to span the 10 MHz bandwidth of the PHY preamble 204. For example, the OFDM symbols of the portion of the PHY preamble 204 are generated using the same FFT size and therefore the same number of OFDM tones as defined by the IEEE 802.11a standard for a 20 MHz bandwidth, but using a sampling rate that is reduced by a factor of two (x2) relative to the sampling rate specified by the IEEE 802.11a standard (downclocked). Thus, in one embodiment, the OFDM tone spacing in the portion of the PHY preamble 204 is reduced by a factor of two (x2) relative to the OFDM tone spacing defined by the IEEE 802.11a standard. In one embodiment, the OFDM numerology and downclocking factor used to generate the portion of the PHY preamble 204 correspond to the OFDM numerology and downclocking factor specified for generating a PHY preamble according to a second communication protocol (e.g., the IEEE 802.11p standard).

[0055] In one embodiment, the PHY data portion 208 includes a plurality of OFDM symbols, and each field of the PHY data portion 208, such as the PHY data segment 252 and the PHY midamble (s) 256, includes one or more OFDM symbols. Each OFDM symbol of the PHY data portion 208 is generated based on OFDM numerology defined by the fourth wireless communication standard for a bandwidth greater than the bandwidth of the PPDU 200 and using a downclocking factor to generate the PHY data portion 208 to span the narrower bandwidth of the PPDU 200. For example, the PHY data portion 208 is generated based on OFDM numerology defined by the IEEE 802.11ac standard for a 20 MHz bandwidth and using a downclocking factor of two (x2) to generate the PHY data portion 208 to span a 10 MHz bandwidth. Thus, in one embodiment, for a 10 MHz wide PPDU, each OFDM symbol in the PHY data portion 208 has the same format as specified in the IEEE 802.11ac standard for a 40 MHz bandwidth, but the tone spacing is reduced by a factor of two (x2). In one embodiment, while an OFDM symbol generated according to the IEEE 802.11ac standard for a 20 MHz bandwidth includes 64 tones with a spacing of 156.25 kHz between consecutive OFDM tones, each OFDM symbol of the PHY data portion 208 includes 64 tones with a spacing of 78.125 kHz between consecutive OFDM tones.

[0056] In some embodiments, each of the NGV-STF 240 and the NGV-LTF(s) 244 includes an OFDM symbol that is generated based on OFDM numerology defined by a fourth wireless communication standard for a bandwidth greater than the bandwidth of the PPDU 200 and using a downclocking factor to generate the NGV-STF 240 and the NGV-LTF(s) 244 to span the narrower bandwidth of the PPDU 200. For example, the NGV-STF 240 and the NGV-LTF(s) 244 are generated based on OFDM numerology defined by the IEEE 802.11ac standard for a 20 MHz bandwidth and using a downclocking factor of two (x2) to generate the NGV-STF 240 and the LTF(s) 244 to span a 10 MHz bandwidth. Thus, in one embodiment, for a 10 MHz wide PPDU, each OFDM symbol in the NGV-STF 240 and NGV-LTF(s) 244 has the same format as specified in the IEEE 802.11ac standard for a 40 MHz bandwidth, but the tone spacing is reduced by a factor of two (x2).

[0057] Figure 2B According to an embodiment, a method for transmitting data in a vehicle communication network such as a vehicle communication network 110 ( Figure 1 ) is another example PPDU 270 transmitted in a vehicle communication network. According to one embodiment, the network interface device 122 ( Figure 1 ) is configured to generate and transmit a PPDU, such as PPDU 270, to one or more client stations 154. In one embodiment, the network interface device 162 ( Figure 1 ) is also configured to generate a PPDU, such as PPDU 270, and transmit it to the AP 114 or another client station 154. In one embodiment, the PHY processor 130 / 170 is configured to generate a PPDU, such as PPDU 270. In one embodiment, the PHY processor 130 / 170 is configured to receive and process a PPDU, such as PPDU 270.

[0058] According to one embodiment, PPDU 270 complies with a first communication protocol (e.g., IEEE 802.11bd standard). Figure 2A The PPDU 200 spans a 10MHz frequency bandwidth, while Figure 2B The PPDU 270 spans a frequency bandwidth of 20 MHz. Figure 2B The PPDU 270 is similar to Figure 2A PPDU 200, and for the sake of brevity, elements with the same number are not described in detail.

[0059] The PPDU 270 includes a PHY preamble 274 and a PHY data portion 278. The PHY preamble 274 includes a legacy PHY preamble portion 282. The LSTF 216, the LLTF 220, the LSIG 224, the RL-SIG 228 (if included), the NGV-SIG 232, and the RNGV-SIG 236 (if included) are repeated in each of the two 10 MHz frequency sub-bands. In one embodiment, since the legacy PHY preamble 282 is repeated in multiple sub-bands and is generated based on OFDM numerology using a down-conversion factor specified for generating the PHY preamble according to the second communication protocol, a legacy or non-legacy communication device operating using a communication channel corresponding to the 10 MHz sub-band of the PPDU 270 is able to detect the PPDU 270 based on a portion of the legacy PHY preamble 282 in the corresponding 10 MHz sub-band. In one embodiment, the legacy communication device is configured to determine a duration corresponding to the transmission of the PPDU 270 based on a duration information in the LSIG 224 in the corresponding 10 MHz sub-band, and wait for the determined duration before attempting to transmit in the communication medium. For example, in one embodiment, each LSIG 224 has a format at least substantially as specified in the IEEE 802.11p standard and includes information that allows a legacy communication device configured according to the IEEE 802.11p standard rather than the IEEE 802.11bd standard to determine a duration corresponding to the transmission of the PPDU 270 and wait for the determined duration before attempting to transmit in the communication medium.

[0060] In one embodiment, each OFDM symbol in the NGV-STF 240 , NGV-LTF 244 , and PHY data portion 278 is generated to span the entire bandwidth of the PPDU 270 .

[0061] Reference now Figure 2A-2B According to one embodiment, when the PPDU 200 / 270 is transmitted in the ER mode, the LSTF 216 and the LLTF 220 are power-boosted compared to other fields of the PPDU 200 / 270. As an illustrative example, when the PPDU 200 / 270 is transmitted in the ER mode, the LSTF 216 and the LLTF 220 are power-boosted by 3 dB compared to other fields of the PPDU 200 / 270. In other embodiments, when the PPDU 200 / 270 is transmitted in the ER mode, the LSTF 216 and the LLTF 220 are power-boosted by other appropriate amounts other than 3 dB (e.g., 2 dB, 4 dB, etc.).

[0062] Reference again Figure 2A-2B, the PHY midamble 256 includes a training signal field that allows the receiver to update an existing channel estimate or regenerate a channel estimate when receiving the PPDU 200 / 270, which is useful for a vehicle communication environment in which one or more communication devices move at a relatively high speed. As an illustrative example, according to one embodiment, the movement of the transmitter and / or the receiver may cause a Doppler effect at the receiver, and the training signal field of the PHY midamble 256 helps the receiver update or regenerate a channel estimate to mitigate the Doppler effect.

[0063] In one embodiment, each midamble 256 includes a plurality of training signal fields corresponding to the number of spatial streams via which the PPDU 200 is transmitted. As an illustrative example, when the PPDU 200 / 270 is transmitted via a single spatial stream, each midamble 256 is a single training signal field, and when the PPDU 200 / 270 is transmitted via two spatial streams, each midamble 256 includes two training signal fields.

[0064] In one embodiment, each training signal field of the midamble (multiple) 256 is based on the VHT-LTF defined by the IEEE 802.11ac standard. For example, according to one embodiment, for a 10 MHz PPDU, such as Figure 2A In the PPDU 200 of FIG. 1, each training signal field of the midamble (multiple) 256 is generated as a 2x down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard for a 20 MHz PPDU. In another example, according to one embodiment, for a 20 MHz PPDU, such as Figure 2B In the PPDU 270 of FIG. 8 , each training signal field of the midamble (s) 256 is generated as a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU.

[0065] Figure 3 According to one embodiment, Figure 2A and Figure 2B FIG. 3 is a diagram of an example of a training signal field 300 in a midamble (multiple) 256 of FIG. The training signal field 300 includes a training signal portion 304 based on a VHT-LTF defined by the IEEE 802.11ac standard. For example, according to one embodiment, for a 10 MHz PPDU (such as Figure 2A PPDU 200), the training signal portion 304 is generated as a 2x down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard for a 20 MHz PPDU. In another example, according to one embodiment, for a 20 MHz PPDU, such as Figure 2BIn the PPDU 270, the training signal portion 304 is generated as a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU.

[0066] According to one embodiment, the cyclic prefix 312 includes a copy of the ending time period 316 of the second training signal portion 308. In other embodiments, the cyclic prefix 312 includes another suitable signal. In other embodiments, the cyclic prefix 312 is omitted.

[0067] Figure 4 According to another embodiment, Figure 2A and Figure 2B FIG. 4 is another example of a training signal field 400 in a midamble (multiple) 256 of FIG. The training signal field 400 includes a first training signal portion 404, a second training signal portion 408, and a cyclic prefix 412. Each of the first training signal portion 404 and the second training signal portion 408 is based on a VHT-LTF defined by the IEEE 802.11ac standard. For example, according to one embodiment, for a 10 MHz PPDU, such as Figure 2A PPDU200, each of the first training signal portion 404 and the second training signal portion 408 is generated as a 2x down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard for a 20 MHz PPDU. In another example, according to one embodiment, for a 20 MHz PPDU, such as Figure 2B PPDU 270, each of the first training signal portion 404 and the second training signal portion 408 is generated as a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU. In one embodiment, each of the first training signal portion 404 and the second training signal portion 408 is generated as a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU. Figure 3 The training signal portion 304 is the same.

[0068] According to one embodiment, the cyclic prefix 412 includes a copy of the ending time period 416 of the second training signal portion 408. In other embodiments, the cyclic prefix 412 includes another suitable signal. In still other embodiments, the cyclic prefix 412 is omitted.

[0069] Due to the repetition provided by the two training signal portions 404 and 408, the training signal field 400 provides a 3dB gain compared to a training signal field having only one of the portions 404 and 408. This 3dB gain provides an effect similar to the power boost applied to the LLTF 220 in the ER mode described above.

[0070] According to one embodiment, the training signal field 400 is combined with Figure 3 The training signal field 400 has a longer duration than the training signal field 300. For example, according to one embodiment, the duration of the training signal field 400 is longer than the duration of the training signal field 300 by at least the duration of the training signal portion 304.

[0071] Figure 5 According to yet another embodiment, Figure 2A and Figure 2B FIG. 5 is a diagram of another example training signal field 500 in the midamble (multiple) 256 of FIG. The training signal field 500 includes a compressed VHT-LTF 504 and a cyclic prefix 508. According to one embodiment, the cyclic prefix 508 includes a copy of the end time period of the compressed VHT-LTF 504. In other embodiments, the cyclic prefix 508 includes another suitable signal. In other embodiments, the cyclic prefix 508 is omitted.

[0072] Compared to the VHT-LTF used for the midamble described above, the compressed VHT-LTF 504 has a shorter (or compressed) duration. In one embodiment, the compressed VHT-LTF 504 is generated by setting every other OFDM tone in the VHT-LTF tone sequence defined by the IEEE 802.11ac standard to zero before performing the IFFT and truncating the resulting time domain sequence in half after performing the IFFT. In one embodiment, the IFFT is a 64-tone IFFT for a 10 MHz wide PPDU and a 128-tone IFFT for a 20 MHz wide PPDU.

[0073] In another embodiment, the compressed VHT-LTF 504 is generated by applying a smaller size IFFT to a sequence including every other tone value in the VHT-LTF tone sequence defined by the IEEE 802.11ac standard. For example, in one embodiment, a 32-tone IFFT is used for a 10 MHz wide PPDU, while a 128-tone IFFT is used for a 20 MHz wide PPDU.

[0074] Because the compressed VHT-LTF 504 has a shorter (or compressed) duration than other VHT-LTFs used for midamble as described above, less communication medium time is consumed for overhead (compared to other VHT-LTFs used for midamble as described above), allowing more communication medium time to be used for transmitting user data.

[0075] According to one embodiment, the training signal field 500 is combined with Figure 3The training signal field 500 has a shorter duration than the training signal field 300. For example, according to one embodiment, the duration of the training signal field 500 is shorter than the duration of the training signal field 300 by at least half of the duration of the training signal portion 304.

[0076] Reference now Figure 3-Figure 5 In an illustrative embodiment, the training signal field 300 (excluding the cyclic prefix 312) has a duration of X, where X is a suitable duration; the training signal field 400 (excluding the cyclic prefix 412) has a duration of 2X; and the training signal field 500 (excluding the cyclic prefix 508) has a duration of X / 2. The training signal field 500 may be referred to as a compressed training signal field, while the training signal field 300 and the training signal field 400 may be referred to as uncompressed training signal fields. In one embodiment, X is equal to the duration of the VHT-LTF defined by the IEEE 802.11ac standard multiplied by 2. In another embodiment, X is equal to the duration of the VHT-LTF without a cyclic prefix defined by the IEEE 802.11ac standard multiplied by 2. In one embodiment, X is 8 microseconds. In other embodiments, X has another suitable duration.

[0077] In some embodiments, two or more of the training signal field 300, the training signal 400, and the training signal 500 are used in a single communication protocol for vehicle communication. For example, in some embodiments, two or more of the training signal field 300, the training signal 400, and the training signal 500 are used in corresponding transmission modes defined by the communication protocol for vehicle communication. As an illustrative embodiment, the training signal 400 is used for the ER transmission mode, the training signal 500 is used for the high throughput mode, and the training signal 400 is used for another transmission mode (e.g., normal mode, default mode, etc.) different from the ER transmission mode and the high throughput mode.

[0078] Figure 6 is a flow chart of an example method 600 for wireless communication in a vehicle communication network according to an embodiment. Figure 1 In various embodiments, method 600 is implemented by a network interface device, such as network interface device 122 or network interface device 162. For example, in one such embodiment, a PHY processor, such as PHY processor 130 or PHY processor 170, is configured to implement method 600. In other embodiments, method 600 is implemented by another suitable communication device.

[0079] At block 604, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble for the PPDU to be transmitted in the vehicle communication network according to the communication protocol for vehicle communication. For example, according to various embodiments, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble, such as the following reference Figure 2A PHY preamble 204, reference Figure 2B The described PHY preamble 274 or another suitable PHY preamble.

[0080] At block 608, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a plurality of PHY data segments of the PPDU. For example, according to various embodiments, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a PHY data segment, such as reference Figure 2A and Figure 2B The PHY data segment 252 described above or another suitable PHY preamble.

[0081] At block 612, the communications device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the PHY midamble generator 142, generated by the network interface device 162, generated by the PHY processor 170, generated by the PHY midamble generator 192, etc.) one or more PHY midambles of the PPDU, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments generated at block 608. Each PHY midamble includes one or more training signal fields, and generating the one or more PHY midambles at block 612 includes generating each training signal field to include a portion based on a VHT-LTF defined by the IEEE 802.11ac standard.

[0082] In one embodiment, for a 10 MHz PPDU, such as Figure 2A PPDU 200, generating one or more PHY midambles at block 612 includes generating each training signal field to include a 2x down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard for a 20 MHz PPDU. In one embodiment, for a 20 MHz PPDU, such as Figure 2BFor the PPDU 270, generating one or more PHY midambles at block 612 includes generating each training signal field to include a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU.

[0083] In one embodiment, generating one or more PHY midambles at block 612 includes generating each midamble to include a reference Figure 3 The training signal field 300 is described.

[0084] In one embodiment, generating one or more PHY midambles at block 612 includes: when the PPDU is to be transmitted according to a non-ER mode defined by the communication protocol, generating each training signal field to include a portion based on a VHT-LTF defined by the IEEE 802.11ac standard. In another embodiment, generating one or more PHY midambles at block 612 includes: in response to the communication device determining that the PPDU is to be transmitted according to a non-ER mode defined by the communication protocol, generating each training signal field to include a portion based on a VHT-LTF defined by the IEEE 802.11ac standard. In other embodiments, when the PPDU is to be transmitted according to any one of a plurality of modes defined by the communication protocol (including the ER mode), each training signal field is generated at block 612 to include a portion based on a VHT-LTF defined by the IEEE 802.11ac standard.

[0085] At block 616, the communication device transmits (e.g., the network interface device 122 transmits, the PHY processor 130 transmits, the network interface device 162 transmits, the PHY processor 170 transmits, etc.) the PPDU in the vehicle communication network. In one embodiment, transmitting the PPDU at block 616 includes transmitting the PHY preamble generated at block 604, transmitting the PHY data segment generated at block 608, and transmitting one or more PHY midambles generated at block 612 between corresponding pairs of adjacent PHY data segments generated at block 608.

[0086] Figure 7 is a flow chart of another example method 700 for wireless communication in a vehicle communication network according to another embodiment. Figure 1 In various embodiments, method 700 is implemented by a network interface device, such as network interface device 122 or network interface device 162. For example, in one such embodiment, a PHY processor, such as PHY processor 130 or PHY processor 170, is configured to implement method 700. In other embodiments, method 700 is implemented by another suitable communication device.

[0087] At block 704, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble for the PPDU to be transmitted in the vehicle communication network according to the communication protocol for vehicle communication. For example, according to various embodiments, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble, such as the following reference Figure 2A PHY preamble 204, reference Figure 2B The described PHY preamble 274 or another suitable PHY preamble.

[0088] At block 708, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a plurality of PHY data segments of the PPDU. For example, according to various embodiments, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a PHY data segment, such as reference Figure 2A and Figure 2B The PHY data segment 252 described above or another suitable PHY preamble.

[0089] At block 712, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the PHY midamble generator 142, generated by the network interface device 162, generated by the PHY processor 170, generated by the PHY midamble generator 192, etc.) one or more PHY midambles of the PPDU, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments generated at block 708. Each PHY midamble includes one or more training signal fields, and generating the one or more PHY midambles at block 712 includes generating each training signal field to include i) a first portion based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard.

[0090] In one embodiment, for a 10 MHz PPDU, such as Figure 2A PPDU 200, generating one or more PHY midambles at block 712 includes generating each of the first and second parts of each training signal field to include a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 20 MHz PPDU. In one embodiment, for a 20 MHz PPDU, such as Figure 2BPPDU 270, generating one or more PHY midambles at block 712 includes generating each of the first and second portions of each training signal field to include a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU.

[0091] In one embodiment, generating one or more PHY midambles at block 712 includes generating each midamble to include a reference Figure 4 The training signal field 400 is described.

[0092] In one embodiment, generating the one or more PHY midambles at block 712 includes: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating each training signal field to include i) a first portion based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard. In another embodiment, generating the one or more PHY midambles at block 712 includes: in response to the communication device determining that the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating each training signal field to include i) a first portion based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard. In other embodiments, when the PPDU is to be transmitted according to any one of a plurality of modes defined by the communication protocol (including a non-ER mode), each training signal field is generated at block 712 to include i) a first portion based on a VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on a VHT-LTF defined by the IEEE 802.11ac standard.

[0093] At block 716, the communication device transmits (e.g., the network interface device 122 transmits, the PHY processor 130 transmits, the network interface device 162 transmits, the PHY processor 170 transmits, etc.) the PPDU in the vehicle communication network. In one embodiment, transmitting the PPDU at block 716 includes transmitting the PHY preamble generated at block 704, transmitting the PHY data segment generated at block 708, and transmitting one or more PHY midambles generated at block 712 between corresponding pairs of adjacent PHY data segments generated at block 708.

[0094] Figure 8 is a flow chart of yet another example method 800 for wireless communication in a vehicle communication network according to another embodiment. Figure 1In various embodiments, method 800 is implemented by a network interface device, such as network interface device 122 or network interface device 162. For example, in one such embodiment, a PHY processor, such as PHY processor 130 or PHY processor 170, is configured to implement method 800. In other embodiments, method 800 is implemented by another suitable communication device.

[0095] At block 804, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble for a PPDU to be transmitted in the vehicle communication network according to a communication protocol for vehicle communication. For example, according to various embodiments, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble, such as reference Figure 2A PHY preamble 204, reference Figure 2B The described PHY preamble 274 or another suitable PHY preamble.

[0096] At block 808, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a plurality of PHY data segments of the PPDU. For example, according to various embodiments, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a PHY data segment, such as reference Figure 2A and Figure 2B The PHY data segment 252 described above or another suitable PHY preamble.

[0097] At block 812, the communications device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the PHY midamble generator 142, generated by the network interface device 162, generated by the PHY processor 170, generated by the PHY midamble generator 192, etc.) one or more PHY midambles of the PPDU, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments generated at block 808. Each PHY midamble includes one or more training signal fields, and generating the one or more PHY midambles at block 812 includes generating each training signal field to include a compressed training signal field based on a VHT-LTF defined by the IEEE 802.11ac standard.

[0098] In one embodiment, the compressed training signal field generated at block 812 is generated by setting every other OFDM tone in the VHT-LTF tone sequence defined by the IEEE 802.11ac standard to zero before performing an IFFT and truncating the resulting time domain sequence in half after performing the IFFT. In one embodiment, the IFFT is a 64-tone IFFT for a 10 MHz wide PPDU and a 128-tone IFFT for a 20 MHz wide PPDU.

[0099] In another embodiment, the compressed training signal field generated at block 812 is generated by applying a smaller size IFFT to a sequence including every other tone value in a VHT-LTF tone sequence defined by the IEEE 802.11ac standard. For example, in one embodiment, a 32-tone IFFT is used for a 10 MHz wide PPDU, while a 128-tone IFFT is used for a 20 MHz wide PPDU.

[0100] In one embodiment, generating one or more PHY midambles at block 812 includes generating each midamble to include a reference Figure 5 A training signal field 500 is described.

[0101] In one embodiment, generating one or more PHY midambles at block 812 includes generating each training signal field to include a compressed training signal field when the PPDU is to be transmitted according to a high throughput mode defined by the communication protocol. In another embodiment, generating one or more PHY midambles at block 812 includes generating each training signal field to include a compressed training signal field in response to the communication device determining that the PPDU is to be transmitted according to a high throughput mode defined by the communication protocol. In other embodiments, each training signal field is generated at block 612 to include a compressed training signal field when the PPDU is to be transmitted according to any one of a plurality of modes defined by the communication protocol, including a non-high throughput mode.

[0102] At block 816, the communication device transmits (e.g., the network interface device 122 transmits, the PHY processor 130 transmits, the network interface device 162 transmits, the PHY processor 170 transmits, etc.) the PPDU in the vehicle communication network. In one embodiment, transmitting the PPDU at block 816 includes transmitting the PHY preamble generated at block 804, transmitting the PHY data segment generated at block 808, and transmitting one or more PHY midambles generated at block 812 between corresponding pairs of adjacent PHY data segments generated at block 808.

[0103] In some embodiments, two or more of the methods 600, 700, and 800 are implemented by a communication device operating according to a single communication protocol for vehicle communication. For example, in some embodiments, two or more of the methods 600, 700, and 800 are performed in conjunction with transmitting different packets according to corresponding transmission modes defined by the communication protocol for vehicle communication. As an illustrative embodiment, the method 700 is performed when transmitting packets according to the ER transmission mode, the method 800 is performed when transmitting packets according to the high throughput mode, and the method 600 is performed when transmitting packets according to another transmission mode (e.g., normal mode, default mode, etc.) different from the ER transmission mode and the high throughput mode.

[0104] Fig. 9 is a flow chart of yet another example method 900 for wireless communication in a vehicle communication network according to another embodiment. Figure 1 In various embodiments, method 900 is implemented by a network interface device, such as network interface device 122 or network interface device 162. For example, in one such embodiment, a PHY processor, such as PHY processor 130 or PHY processor 170, is configured to implement method 900. In other embodiments, method 900 is implemented by another suitable communication device.

[0105] At block 904, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble for a PPDU to be transmitted in the vehicle communication network according to a communication protocol for vehicle communication. For example, according to various embodiments, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the network interface device 162, generated by the PHY processor 170, etc.) a PHY preamble, such as reference Figure 2A PHY preamble 204, reference Figure 2B The described PHY preamble 274 or another suitable PHY preamble.

[0106] At block 908, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a plurality of PHY data segments of the PPDU. For example, according to various embodiments, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the network interface device 162 generates, the PHY processor 170 generates, etc.) a PHY data segment, such as reference Figure 2A and Figure 2B The PHY data segment 252 described above, or another suitable PHY preamble.

[0107] At block 912, the communication device determines (e.g., the network interface device 122 determines, the PHY processor 130 determines, the network interface device 162 determines, the PHY processor 170 determines, etc.) whether the PPDU is to be transmitted according to the ER mode. In response to the communication device determining that the PPDU is to be transmitted according to the ER mode, the flow proceeds to block 916.

[0108] At block 916, the communications device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the PHY midamble generator 142, generated by the network interface device 162, generated by the PHY processor 170, generated by the PHY midamble generator 192, etc.) one or more PHY midambles of the PPDU, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments generated at block 908. Each PHY midamble includes one or more training signal fields, and generating the one or more PHY midambles at block 916 includes generating each training signal field to include i) a first portion based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard.

[0109] In one embodiment, for a 10 MHz PPDU (such as Figure 2A PPDU 200), generating one or more PHY midambles at block 916 includes generating each of the first and second parts of each training signal field to include a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 20 MHz PPDU. In one embodiment, for a 20 MHz PPDU, such as Figure 2B PPDU 270, generating one or more PHY midambles at block 916 includes generating each of the first and second portions of each training signal field to include a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU.

[0110] In one embodiment, generating one or more PHY midambles at block 916 includes generating each midamble to include a reference Figure 4 The training signal field 400 is described.

[0111] In one embodiment, generating the one or more PHY midambles at block 916 includes: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating each training signal field to include i) a first portion based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard. In another embodiment, generating the one or more PHY midambles at block 916 includes: in response to the communication device determining that the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating each training signal field to include i) a first portion based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard. In other embodiments, when the PPDU is to be transmitted according to any one of a plurality of modes defined by the communication protocol (including a non-ER mode), each training signal field is generated at block 916 to include i) a first portion based on a VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on a VHT-LTF defined by the IEEE 802.11ac standard.

[0112] On the other hand, in response to the communication device determining at block 912 that the PPDU is not to be transmitted in accordance with the ER mode, the flow proceeds to block 920. At block 920, the communication device determines (e.g., the network interface device 122 determines, the PHY processor 130 determines, the network interface device 162 determines, the PHY processor 170 determines, etc.) whether the PPDU is to be transmitted in accordance with the high-throughput mode. In response to the communication device determining that the PPDU is to be transmitted in accordance with the high-throughput mode, the flow proceeds to block 924.

[0113] At block 924, the communication device generates (e.g., generated by the network interface device 122, generated by the PHY processor 130, generated by the PHY midamble generator 142, generated by the network interface device 162, generated by the PHY processor 170, generated by the PHY midamble generator 192, etc.) one or more PHY midambles of the PPDU, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments generated at block 908. Each PHY midamble includes one or more training signal fields, and generating the one or more PHY midambles at block 924 includes generating each training signal field to include a compressed training signal field based on a VHT-LTF defined by the IEEE 802.11ac standard.

[0114] In one embodiment, the compressed training signal field generated at block 924 is generated by setting every other OFDM tone in the VHT-LTF tone sequence defined by the IEEE 802.11ac standard to zero before performing an IFFT and truncating the resulting time domain sequence in half after performing the IFFT. In one embodiment, the IFFT is a 64-tone IFFT for a 10 MHz wide PPDU and a 128-tone IFFT for a 20 MHz wide PPDU.

[0115] In another embodiment, the compressed training signal field generated at block 924 is generated by applying a smaller size IFFT to a sequence including every other tone value in a VHT-LTF tone sequence defined by the IEEE 802.11ac standard. For example, in one embodiment, a 32-tone IFFT is used for a 10 MHz wide PPDU, while a 128-tone IFFT is used for a 20 MHz wide PPDU.

[0116] In one embodiment, generating one or more PHY midambles at block 924 includes generating each midamble to include a reference Figure 5 A training signal field 500 is described.

[0117] On the other hand, in response to the communication device determining at block 920 that the PPDU is not to be transmitted according to the high throughput mode, the flow proceeds to block 928. At block 928, the communication device generates (e.g., the network interface device 122 generates, the PHY processor 130 generates, the PHY midamble generator 142 generates, the network interface device 162 generates, the PHY processor 170 generates, the PHY midamble generator 192 generates, etc.) one or more PHY midambles for the PPDU, each of which is to be transmitted between a corresponding pair of adjacent PHY data segments generated at block 908. Each PHY midamble includes one or more training signal fields, and generating the one or more PHY midambles at block 928 includes generating each training signal field to include a portion based on the VHT-LTF defined by the IEEE 802.11ac standard.

[0118] In one embodiment, for a 10 MHz PPDU, such as Figure 2A PPDU 200, generating one or more PHY midambles at block 928 includes generating each training signal field to include a 2x down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard for a 20 MHz PPDU. In one embodiment, for a 20 MHz PPDU, such as Figure 2BFor the PPDU 270, generating one or more PHY midambles at block 928 includes generating each training signal field to include a 2x down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard for a 40 MHz PPDU.

[0119] In one embodiment, generating one or more PHY midambles at block 928 includes generating each midamble to include a reference Figure 3 The training signal field 300 is described.

[0120] At block 932, the communication device transmits (e.g., the network interface device 122 transmits, the PHY processor 130 transmits, the network interface device 162 transmits, the PHY processor 170 transmits, etc.) the PPDU in the vehicle communication network. In one embodiment, transmitting the PPDU at block 932 includes transmitting the PHY preamble generated at block 904, transmitting the PHY data segment generated at block 908, and transmitting one or more PHY midambles generated at blocks 916, 924, or 928 between pairs of adjacent PHY data segments of the response generated at block 908.

[0121] In various embodiments, method 900 is modified by changing the order of blocks, omitting blocks, adding additional blocks, etc. As an illustrative example, according to another embodiment, the order of blocks 912 and 920 is switched. As another illustrative example, block 912 may be replaced with a similar block that checks whether the PPDU is to be transmitted according to a mode different from the ER mode (e.g., the third transmission mode) and the high-throughput mode is to be used, and according to another embodiment, the positions of blocks 916 and 928 may be swapped. Similarly, as another illustrative example, block 920 may be replaced with a similar block that checks whether the PPDU is to be transmitted according to a mode different from the ER mode (e.g., the third transmission mode) and the high-throughput mode is to be used, and according to another embodiment, the positions of blocks 920 and 928 may be swapped.

[0122] Embodiment 1: A method for wireless communication in a vehicle communication network, the method comprising: generating a PHY preamble code for a PPDU transmitted in the vehicle communication network according to a communication protocol for vehicle communication at a communication device; generating multiple PHY data segments of the PPDU at the communication device; generating one or more PHY midambles at the communication device, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble includes one or more training signal fields, wherein generating the one or more PHY midambles comprises: when the PPDU is to be transmitted according to an ER mode defined by the communication protocol, generating each training signal field to include i) a first part based on a VHT-LTF defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard; and transmitting the PPDU in the vehicle communication network by the communication device.

[0123] Embodiment 2: The method according to embodiment 1, wherein generating the one or more PHY midambles further comprises: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating each training signal field to further include a cyclic prefix.

[0124] Embodiment 3: The method of Embodiment 2, wherein generating each training signal field to include the cyclic prefix comprises generating each training signal field to include an end time period of the second portion of the training signal field.

[0125] Embodiment 4: A method according to any one of embodiments 1 to 3, wherein generating the one or more PHY midambles further comprises: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating each training signal field to include a down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part and including the down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

[0126] Embodiment 5: A method according to any one of Embodiments 1 to 4, wherein generating the one or more PHY midambles includes: when the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode, generating each training signal field to include the first part and omitting the second part.

[0127] Embodiment 6: A method according to any one of embodiments 1 to 4, wherein generating the one or more PHY midambles includes: when the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode, generating each training signal field to include a time-compressed training signal based on the VHT-LTF defined by the IEEE 802.11ac standard, and the duration of the time-compressed training signal is shorter than the duration of the first part included when the PPDU is to be transmitted according to the ER mode.

[0128] Embodiment 7: A communication device configured to operate in a vehicle communication network, the communication device comprising: a wireless network interface device. The wireless network interface device comprises one or more IC devices, the one or more IC devices being configured to: generate a PHY preamble for a PPDU to be transmitted in the vehicle communication network according to a communication protocol for vehicle communication; generate a plurality of PHY data segments of the PPDU; generate one or more PHY midambles, each of which is to be transmitted between a corresponding pair of adjacent PHY data segments, and each of which comprises one or more training signal fields, wherein generating the one or more PHY midambles comprises: when the PPDU is to be transmitted according to an extended range (ER) mode defined by the communication protocol, generating each training signal field to include i) a first part based on a VHT-LTF defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard; and control the wireless network interface device to transmit the PPDU in the vehicle communication network.

[0129] Embodiment 8: The communication device according to embodiment 7, wherein the one or more IC devices are further configured to: generate each training signal field to further include a cyclic prefix when the PPDU is to be transmitted according to the ER mode defined by the communication protocol.

[0130] Embodiment 9: The communication device of Embodiment 8, wherein the one or more IC devices are further configured to generate each training signal field to include an end time period of the second portion of the training signal field.

[0131] Embodiment 10: A communication device according to any one of Embodiments 7 to 9, wherein the one or more IC devices are further configured to: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generate each training signal field to include a down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part and include the down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

[0132] Embodiment 11: A communication device according to any one of Embodiments 7 to 10, wherein the one or more IC devices are further configured to: generate each training signal field to include the first part and omit the second part when the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode.

[0133] Embodiment 12: A communication device according to any one of Embodiments 7 to 10, wherein the one or more IC devices are further configured to: when the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode, generate each training signal field to include a time-compressed training signal based on the VHT-LTF defined by the IEEE 802.11ac standard, and the duration of the time-compressed training signal is shorter than the duration of the first part included when the PPDU is to be transmitted according to the ER mode.

[0134] Embodiment 13: A method for accessing a communication channel in a vehicle communication network, the method comprising: generating a PHY preamble code of a PPDU for transmission in the vehicle communication network according to a communication protocol for vehicle communication at a communication device; generating a plurality of PHY data segments of the PPDU at the communication device; selecting one or more PHY midamble formats from a set of multiple different PHY midamble formats based on a transmission mode of the PPDU at the communication device, wherein the set of multiple different PHY midamble formats includes i) a first format corresponding to an extended range transmission mode defined by the communication protocol, the first format using an uncompressed training signal field, and ii) a second format corresponding to a high throughput transmission mode defined by the communication protocol, the second format using a compressed training signal field; generating the one or more PHY midambles at the communication device according to the selected format, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble including one or more training signal fields, wherein generating each PHY midamble includes: i) selectively including an uncompressed training signal field when the first format is selected, and ii) selectively including a compressed training signal field when the second format is selected; and transmitting the PPDU in the vehicle communication network by the communication device.

[0135] Embodiment 14: A method according to embodiment 13, wherein generating the one or more PHY midambles according to the selected format includes: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol: generating each training signal field to include i) a first part based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard.

[0136] Embodiment 15: A method according to embodiment 14, wherein generating the one or more PHY midambles further comprises: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating each training signal field to include a down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part, and including the down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

[0137] Embodiment 16: A method according to any one of Embodiments 13 to 15, wherein generating the one or more PHY midambles according to the selected format includes: when the PPDU is to be transmitted according to the high throughput mode defined by the communication protocol: generating each training signal field to include a time-compressed training signal based on the VHT-LTF defined by the IEEE 802.11ac standard, the duration of each training signal field being shorter than the duration of each training signal field generated when the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode.

[0138] Embodiment 17: A method according to any one of Embodiments 13 to 16, wherein generating the one or more PHY midambles according to the selected format includes: when the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode: generating each training signal field to include a down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard, and the duration of each training signal field is shorter than the duration of each training signal field generated when the PPDU is to be transmitted according to the ER mode.

[0139] Embodiment 18: An apparatus associated with a communication device configured to operate in a vehicle communication network, the apparatus comprising: a wireless network interface device. The wireless network interface device comprises one or more IC devices, the one or more IC devices being configured to: generate a PHY preamble code for a PPDU for transmission in the vehicle communication network according to a communication protocol for vehicle communication; generate multiple PHY data segments of the PPDU; select one or more PHY midamble formats from a set of multiple different PHY midamble formats based on the transmission mode of the PPDU, wherein the set of multiple different PHY midamble formats comprises i) a first format corresponding to an extended range transmission mode defined by the communication protocol, the first format using an uncompressed training signal field, and ii) a first format corresponding to a transmission mode defined by the communication protocol. A second format corresponding to a defined high-throughput transmission mode, wherein the second format uses a compressed training signal field; generating the one or more PHY midambles according to the selected format, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble includes one or more training signal fields, wherein generating each PHY midamble includes: i) selectively including an uncompressed training signal field when the first format is selected, and ii) selectively including a compressed training signal field when the second format is selected; and controlling the wireless network interface device to transmit the PPDU in the vehicle communication network.

[0140] Embodiment 19: A communication device according to embodiment 18, wherein the one or more IC devices are configured to: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol: generate each training signal field to include i) a first part based on the VHT-LTF defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE802.11ac standard.

[0141] Embodiment 20: A communication device according to embodiment 19, wherein the one or more IC devices are configured to: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generate each training signal field to include a down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part, and include the down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

[0142] Embodiment 21: A communication device according to any one of Embodiments 18 to 20, wherein the one or more IC devices are configured to: when the PPDU is to be transmitted according to the high throughput mode defined by the communication protocol: generate each training signal field to include a time-compressed training signal based on the VHT-LTF defined by the IEEE 802.11ac standard, and the duration of each training signal field is shorter than the duration of each training signal field generated when the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode.

[0143] Embodiment 22: A communication device according to any one of Embodiments 18 to 21, wherein the one or more IC devices are configured to: when the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode: generate each training signal field to include a down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard, and the duration of each training signal field is shorter than the duration of each training signal field generated when the PPDU is to be transmitted according to the ER mode.

[0144] At least some of the various blocks, operations, and techniques described above may be implemented using hardware, a processor executing firmware instructions, a processor executing software instructions, or any combination thereof. When implemented using a processor executing software or firmware instructions, the software or firmware instructions may be stored in any computer-readable memory, such as in RAM, ROM, flash memory, integrated memory of a processor, etc. The software or firmware instructions may include machine-readable instructions that, when executed by a processor, cause the processor to perform various actions.

[0145] When implemented in hardware, the hardware may include one or more discrete components, one or more ICs, application specific integrated circuits (ASICs), programmable logic devices (PLDs), and the like.

[0146] Although the present invention has been described with reference to specific examples, these examples are intended to be illustrative only and not limiting of the present invention, and changes, additions and / or deletions may be made to the disclosed embodiments without departing from the scope of the present invention.

Claims

1. A method for wireless communication in a vehicle communication network, the method comprising: generating, at a communication device, a PHY preamble of a physical layer PHY protocol data unit PPDU for transmission in the vehicle communication network according to a communication protocol for vehicle communication; generating, at the communication device, a plurality of PHY data segments of the PPDU; One or more PHY midambles are generated at the communication device, each PHY midamble is to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble includes one or more training signal fields, including: determining whether the PPDU is to be transmitted according to an extended range (ER) mode defined by the communication protocol, the ER mode being one of a plurality of transmission modes defined by the communication protocol, wherein the communication protocol defines a corresponding PHY midamble format of a plurality of PHY midamble formats, the corresponding PHY midamble format of the plurality of PHY midamble formats being for use with a corresponding transmission mode of the plurality of transmission modes defined by the communication protocol, and When it is determined that the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating the one or more PHY midambles according to a first PHY midamble format among the plurality of PHY midamble formats, the first PHY midamble format being defined by the communication protocol for use with the ER mode, wherein generating the one or more PHY midambles according to the first PHY midamble format comprises: generating each training signal field to include i) a first portion based on a very high throughput long training field VHT-LTF defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard; and The PPDU is transmitted by the communication device in the vehicle communication network.

2. The method of claim 1 , wherein generating the one or more PHY midambles further comprises: When it is determined that the PPDU is to be transmitted according to the ER mode defined by the communication protocol, each training signal field is generated to further include a cyclic prefix.

3. The method of claim 2, wherein generating each training signal field to include the cyclic prefix comprises generating each training signal field to include an end time period of the second portion of the training signal field.

4. The method of claim 1 , wherein generating the one or more PHY midambles further comprises: When it is determined that the PPDU is to be transmitted according to the ER mode defined by the communication protocol, each training signal field is generated to include a down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part, and to include the down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

5. The method of claim 1 , wherein generating the one or more PHY midambles comprises: When it is determined that the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode, each training signal field is generated to include the first part and omit the second part.

6. The method of claim 1 , wherein generating the one or more PHY midambles comprises: When it is determined that the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode, each training signal field is generated to include a time-compressed training signal based on the VHT-LTF defined by the IEEE 802.11ac standard, the duration of the time-compressed training signal being shorter than the duration of the first part included when the PPDU is to be transmitted according to the ER mode.

7. A communication device configured to operate in a vehicle communication network, the communication device comprising: A wireless network interface device having one or more integrated circuit IC devices, wherein the one or more IC devices are configured to: generating a PHY preamble of a physical layer PHY protocol data unit PPDU for transmission in the vehicle communication network according to a communication protocol for vehicle communication, generating a plurality of PHY data segments of the PPDU, and Generate one or more PHY midambles, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble includes one or more training signal fields, wherein generating the one or more PHY midambles includes: determining whether the PPDU is to be transmitted according to an extended range (ER) mode defined by the communication protocol, the ER mode being one of a plurality of transmission modes defined by the communication protocol, wherein the communication protocol defines a corresponding PHY midamble format of a plurality of PHY midamble formats, the corresponding PHY midamble format of the plurality of PHY midamble formats being for use with a corresponding transmission mode of the plurality of transmission modes defined by the communication protocol, and When it is determined that the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generating the one or more PHY midambles according to a first PHY midamble format among the plurality of PHY midamble formats, the first PHY midamble format being defined by the communication protocol for use with the ER mode, wherein generating the one or more PHY midambles according to the first PHY midamble format comprises: generating each training signal field to include i) a first portion based on a very high throughput long training field (VHT-LTF) defined by the IEEE 802.11ac standard and ii) a second portion based on the VHT-LTF defined by the IEEE 802.11ac standard; The one or more IC devices are further configured to control the wireless network interface device to transmit the PPDU in the vehicle communication network.

8. The communication device of claim 7, wherein the one or more IC devices are further configured to: generate each training signal field to further include a cyclic prefix when it is determined that the PPDU is to be transmitted according to the ER mode defined by the communication protocol.

9. The communication device of claim 8, wherein the one or more IC devices are further configured to generate each training signal field to include an end time period of the second portion of the training signal field.

10. The communication device of claim 7, wherein the one or more IC devices are further configured to, when determining that the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generate each training signal field to include a down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part, and include the down-converted version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

11. The communication device of claim 7, wherein the one or more IC devices are further configured to, when it is determined that the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode, generate each training signal field to include the first part and omit the second part.

12. The communication device of claim 7 , wherein the one or more IC devices are further configured to, when it is determined that the PPDU is to be transmitted according to another mode defined by the communication protocol and different from the ER mode, generate each training signal field to include a time-compressed training signal based on the VHT-LTF defined by the IEEE 802.11ac standard, the duration of the time-compressed training signal being shorter than the duration of the first part included when the PPDU is to be transmitted according to the ER mode.

13. A method for accessing a communication channel in a vehicle communication network, the method comprising: generating, at a communication device, a PHY preamble of a physical layer PHY protocol data unit PPDU for transmission in the vehicle communication network according to a communication protocol for vehicle communication; generating, at the communication device, a plurality of PHY data segments of the PPDU; selecting, at the communication device, one or more PHY midamble formats from a set of a plurality of different PHY midamble formats based on a transmission mode of the PPDU, wherein a corresponding PHY midamble format of the plurality of different PHY midamble formats is defined by the communication protocol for use with a corresponding transmission mode of a plurality of transmission modes defined by the communication protocol, and wherein the set of a plurality of different PHY midamble formats comprises i) a first format defined by the communication protocol, the first format being used with an extended range (ER) mode defined by the communication protocol, the first format using an uncompressed training signal field, and ii) a second format defined by the communication protocol, the second format being used with a high throughput mode defined by the communication protocol, the second format using a compressed training signal field; generating the one or more PHY midambles at the communication device according to the selected format, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble including one or more training signal fields, wherein generating each PHY midamble comprises: i) selectively including an uncompressed training signal field when the first format is selected, and ii) selectively including a compressed training signal field when the second format is selected; as well as The PPDU is transmitted by the communication device in the vehicle communication network.

14. The method of claim 13, wherein generating the one or more PHY midambles according to the selected format comprises: When the PPDU is to be transmitted according to the ER mode defined by the communication protocol: Each training signal field is generated to include i) a first part based on a very high throughput long training field VHT-LTF defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard.

15. The method of claim 14, wherein generating the one or more PHY midambles further comprises: When the PPDU is to be transmitted according to the ER mode defined by the communication protocol, each training signal field is generated to include a down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part, and to include the down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

16. The method of claim 13, wherein generating the one or more PHY midambles according to the selected format comprises: When the PPDU is to be transmitted according to the high throughput mode defined by the communication protocol: Each training signal field is generated to include a time-compressed training signal based on a VHT-LTF defined by the IEEE 802.11ac standard, and a duration of each training signal field is shorter than a duration of each training signal field generated when the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode.

17. The method of claim 13, wherein generating the one or more PHY midambles according to the selected format comprises: When the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode: Each training signal field is generated to include a down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard, and a duration of each training signal field is shorter than a duration of each training signal field generated when the PPDU is to be transmitted according to the ER mode.

18. An apparatus associated with a communication device configured to operate in a vehicle communication network, the apparatus comprising: A wireless network interface device having one or more integrated circuit IC devices, wherein the one or more IC devices are configured to: generating a PHY preamble of a physical layer PHY protocol data unit PPDU for transmission in the vehicle communication network according to a communication protocol for vehicle communication, generating a plurality of PHY data segments of the PPDU, selecting one or more PHY midamble formats from a set of a plurality of different PHY midamble formats based on a transmission mode of the PPDU, wherein a corresponding PHY midamble format of the plurality of different PHY midamble formats is defined by the communication protocol for use with a corresponding transmission mode of a plurality of transmission modes defined by the communication protocol, and wherein the set of a plurality of different PHY midamble formats comprises i) a first format defined by the communication protocol, the first format being for use with an extended range (ER) mode defined by the communication protocol, the first format using an uncompressed training signal field, and ii) a second format defined by the communication protocol, the second format being for use with a high throughput mode defined by the communication protocol, the second format using a compressed training signal field, generating the one or more PHY midambles according to the selected format, each PHY midamble to be transmitted between a corresponding pair of adjacent PHY data segments, and each PHY midamble including one or more training signal fields, wherein generating each PHY midamble comprises: i) selectively including an uncompressed training signal field when the first format is selected, and ii) selectively including a compressed training signal field when the second format is selected, and The wireless network interface device is controlled to transmit the PPDU in the vehicle communication network.

19. The apparatus of claim 18, wherein the one or more IC devices are configured to: when the PPDU is to be transmitted according to the ER mode defined by the communication protocol: Each training signal field is generated to include i) a first part based on a very high throughput long training field VHT-LTF defined by the IEEE 802.11ac standard and ii) a second part based on the VHT-LTF defined by the IEEE 802.11ac standard.

20. The apparatus of claim 19, wherein the one or more IC devices are configured to, when the PPDU is to be transmitted according to the ER mode defined by the communication protocol, generate each training signal field to include a down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard as the first part, and to include the down-clocked version of the VHT-LTF defined by the IEEE 802.11ac standard as the second part.

21. The apparatus of claim 18, wherein the one or more IC devices are configured to: when the PPDU is to be transmitted according to the high throughput mode defined by the communication protocol: Each training signal field is generated to include a time-compressed training signal based on a VHT-LTF defined by the IEEE 802.11ac standard, and a duration of each training signal field is shorter than a duration of each training signal field generated when the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode.

22. The apparatus of claim 18, wherein the one or more IC devices are configured to: when the PPDU is to be transmitted according to another mode different from the ER mode and different from the high throughput mode: Each training signal field is generated to include a down-clocked version of a VHT-LTF defined by the IEEE 802.11ac standard, and a duration of each training signal field is shorter than a duration of each training signal field generated when the PPDU is to be transmitted according to the ER mode.

Images