Methods and apparatus for generation of physical layer protocol data units for vehicular environments

1. A method for wireless communication, the method comprising: selecting, at a communication device, a frequency bandwidth via which a physical layer (PHY) protocol data unit (PPDU) will be transmitted in a vehicular communication network, wherein the frequency bandwidth is selected from a set of permissible frequency bandwidths that includes a 10 MHz bandwidth and a 20 MHz bandwidth; generating, at a communication device, the PPDU

i) according to a downclocking ratio of ½, and

ii) based on an orthogonal frequency division multiplexing (OFDM) numerology defined by an IEEE 802.11ac Standard,

wherein the PPDU is generated to span the selected frequency bandwidth and to include a PHY preamble having a signal field, and wherein:

in response to the selected frequency bandwidth being 10 MHz, the PPDU is generated according to the downclocking ratio of ½ and based on the OFDM numerology defined by the IEEE 802.11ac Standard for 20 MHz PPDUs, and

in response to the selected frequency bandwidth being 20 MHz, the PPDU is generated according to the downclocking ratio of ½ and based on the OFDM numerology defined by the IEEE 802.1 lac Standard for 40 MHz PPDUs;

modulating, at the communication device, the signal field entirely on a single OFDM symbol; and transmitting, by the communication device, the PPDU in the vehicular communication network.

2. The method of claim 1 , further comprising:

selecting, at the communication device, a set of permissible midamble periodicity values, from among a plurality of sets of permissible midamble periodicity values, based on the selected frequency bandwidth; and

selecting, at the communication device, a midamble periodicity value from the selected set of permissible midamble periodicity values;

wherein generating the PPDU comprises generating the PPDU to include a PHY data portion that includes one or more PHY midambles according to the selected midamble periodicity.

3. The method of claim 2 , wherein generating the PPDU includes generating the PHY preamble to include an indication of the selected midamble periodicity value.

4. The method of claim 3 , wherein generating the PPDU includes generating the PHY preamble to further include an indication of the selected frequency bandwidth.

5. The method of claim 3 , wherein:

the indication of the selected midamble periodicity is included in the signal field of the PHY preamble.

6. The method of claim 1 , wherein:

generating the PPDU according to the downclocking ratio ½ comprises generating the PPDU to have to a second OFDM subcarrier spacing that is one half of a first OFDM subcarrier spacing of the IEEE 802.11ac Standard.

7. The method of claim 6 , wherein:

the first OFDM subcarrier spacing is 312.5 kHz; and

the second OFDM subcarrier spacing is 156.25 kHz.

8. The method of claim 1 , further comprising:

selecting, at the communication device, a guard interval (GI) duration value from a set of at least four permissible GI duration values;

wherein generating the PPDU includes:

generating the PPDU according to the selected GI duration value, and

generating the PPDU to include in the PHY preamble having an indication of the selected GI duration value.

9. An apparatus, comprising: a network interface device having one or more integrated circuit (IC) devices configured to: select a frequency bandwidth via which a physical layer (PHY) protocol data unit (PPDU) will be transmitted in a vehicular communication network, wherein the frequency bandwidth is selected from a set of permissible frequency bandwidths that includes a 10 MHz bandwidth and a 20 MHz bandwidth, and generate the PPDU

i) according to a downclocking ratio of ½, and

ii) based on an orthogonal frequency division multiplexing (OFDM) numerology defined by an IEEE 802.1 lac Standard,

wherein the PPDU is generated to span the selected frequency bandwidth and to include a PHY preamble having a signal field, and wherein:

in response to the selected frequency bandwidth being 10 MHz, the PPDU is generated according to the downclocking ratio of ½ and based on a OFDM numerology defined by the IEEE 802.11ac Standard for 20 MHz PPDUs, and

in response to the selected frequency bandwidth being 20 MHz, the PPDU is generated according to the downclocking ratio of ½ and based on a OFDM numerology defined by the IEEE 802.1 lac Standard for 40 MHz PPDUs;

wherein the one or more IC devices are further configured to: modulate the signal field entirely on a single OFDM symbol, and transmit the PPDU in the vehicular communication network.

10. The apparatus of claim 9 , wherein the one or more IC devices are further configured to:

select a set of permissible midamble periodicity values, from among a plurality of sets of permissible midamble periodicity values, based on the selected frequency bandwidth;

select a midamble periodicity value from the selected set of permissible midamble periodicity values; and

generate the PPDU to include a PHY data portion that includes one or more PHY midambles according to the selected midamble periodicity.

11. The apparatus of claim 10 , wherein the one or more IC devices are further configured to generate the PHY preamble to include an indication of the selected midamble periodicity value.

12. The apparatus of claim 11 , wherein the one or more IC devices are further configured to generate the PHY preamble to further include an indication of the selected frequency bandwidth.

13. The apparatus of claim 11 , wherein the one or more IC devices are further configured to:

include the indication of the selected midamble periodicity in the signal field of the PHY preamble.

14. The apparatus of claim 9 , wherein:

generating the PPDU according to the downclocking ratio ½ comprises generating the PPDU to have to a second OFDM subcarrier spacing that is one half of a first OFDM subcarrier spacing of the IEEE 802.11ac Standard.

15. The apparatus of claim 14 , wherein:

the first OFDM subcarrier spacing is 312.5 kHz; and

the second OFDM subcarrier spacing is 156.25 kHz.

16. The apparatus of claim 9 , wherein the one or more IC devices are further configured to:

select a guard interval (GI) duration value from a set of at least four permissible GI duration values;

generate the PPDU according to the selected GI duration value; and

generate the PPDU to include in the PHY preamble an indication of the selected GI duration value.