Midamble for WLAN PHY packets

• US 10,368,391 B1
• Filed: 09/03/2018
• Issued: 07/30/2019
• Est. Priority Date: 07/23/2009
• Status: Active Grant

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Zhang, Hongyuan, Nabar, Rohit U., Srinivasa, Sudhir, Banerjea, Raja, Liu, Yong
• Primary Examiner(s): Lin, Will W
• Application Number:
  US16/120,393
• Time in Patent Office: 330 Days
• CPC Class Codes: H04J 11/0026 of multi-user interference
• CPC Class Codes: H04K 1/00 Secret communication
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2603 Signal structure ensuring backward compatibility with legacy system
• CPC Class Codes: H04L 27/26035 Maintenance of orthogonality, e.g. for signals exchanged between cells or users, or by using covering codes or sequences using different training sequence per antenna H04B7/0684; code allocation H04J13/16
• CPC Class Codes: H04L 27/2613 Structure of the reference signals
• CPC Class Codes: H04L 27/26132 using repetition
• CPC Class Codes: H04L 27/26136 Pilot sequence conveying additional information
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A communication device generates a physical layer (PHY) data unit that includes a PHY preamble and one or more PHY midambles. The communication generates the PHY preamble of the PHY data unit to include i) a signal field having a subfield that indicates that the PHY data unit includes one or more PHY midambles, ii) a short training field (STF) for automatic gain control (AGC) training and synchronization at a receiver, and iii) one or more long training fields (LTFs) for determining a channel estimate at the receiver. The communication generates a data payload of the PHY data unit having i) a set of orthogonal frequency division multiplexing (OFDM) symbols, and ii) one or more PHY midambles. Each of the one or more PHY midambles includes one or more LTFs for determining an updated channel estimate. The communication device transmits the PHY data unit via a wireless communication channel.

Claims

1. A method, comprising:

generating, at a communication device, a first physical layer (PHY) data unit that includes a first PHY preamble and does not include any PHY midambles, including generating the first PHY preamble to include an indicator that the first PHY data unit does not include any PHY midambles, wherein the first PHY data unit includes a first plurality of orthogonal frequency division multiplexing (OFDM) symbols;

transmitting, by the communication device, the first PHY data unit via a wireless communication channel;

generating, at the communication device, a second PHY data unit that includes a second PHY preamble and one or more PHY midambles, wherein the second PHY data unit includes a second plurality of OFDM symbols, wherein generating the second PHY data unit includes;

generating the second PHY preamble of the second PHY data unit to include i) a signal field having a subfield that indicates that the second PHY data unit includes one or more PHY midambles, ii) a short training field (STF) for automatic gain control (AGC) training and synchronization at a receiver, and iii) one or more long training fields (LTFs) for determining a channel estimate at the receiver,

generating a data payload of the second PHY data unit having i) a set of OFDM symbols, among the second plurality of OFDM symbols, and ii) one or more PHY midambles, wherein each of the one or more PHY midambles includes one or more LTFs for determining an updated channel estimate; and

transmitting, by the communication device, the second PHY data unit via the wireless communication channel.

2. The method of claim 1, further comprising:

generating, at the communication device, the one or more midambles so that each of the one or more midambles includes an STF for AGC retraining at the receiver.

3. The method of claim 1, further comprising:

generating, at the communication device, each PHY midamble to include a respective signal field.

4. The method of claim 1, wherein:

the one or more midambles includes a first-occurring midamble in the data payload of the second PHY data unit;

the first-occurring midamble is spaced apart from the second PHY preamble by N_d OFDM symbols;

when the one or more midambles includes multiple midambles, each pair of adjacent midambles in the data payload are spaced apart by N_d OFDM symbols; and

N_d is an integer greater than one.

5. The method of claim 4, wherein:

the one or more midambles is a plurality of midambles;

the plurality of midambles includes a second-occurring midamble in the data payload of the second PHY data unit; and

the second-occurring midamble is spaced apart from the first-occurring midamble by N_d OFDM symbols.

6. The method of claim 5, wherein:

the plurality of midambles includes a third-occurring midamble in the data payload of the second PHY data unit; and

the third-occurring midamble is spaced apart from the second-occurring midamble by N_d OFDM symbols.

7. The method of claim 4, further comprising:

generating, at the communication device, the signal field in the second PHY preamble to indicate N_d.

8. The method of claim 4, further comprising:

selecting, at the communication, N_d from a set of predefined integer values.

9. The method of claim 8, wherein:

wherein the set of predefined integer values consists of two predefined integer values.

10. The method of claim 1, wherein:

a number of LTFs in each PHY midamble varies depending on a number of spatial streams via which the second PHY data unit is transmitted.

11. The method of claim 1, wherein generating the one or more PHY midambles includes, for each PHY midamble:

generating the one or more LTFs using a channel training matrix.

12. An apparatus, comprising:

a network interface device comprising one or more integrated circuit (IC) devices configured to;

generate a first physical layer (PHY) data unit that includes a first PHY preamble and does not include any PHY midambles, including generating the first PHY preamble to include an indicator that the first PHY data unit does not include any PHY midambles, wherein the first PHY data unit includes a first plurality of orthogonal frequency division multiplexing (OFDM) symbols,

transmit the first PHY data unit via a wireless communication channel,

generate a second PHY data unit that includes a second PHY preamble and one or more PHY midambles, wherein the second PHY data unit includes a second plurality of OFDM symbols, wherein generating the second PHY data unit includes;

generating the second PHY preamble of the second PHY data unit to include i) a signal field having a subfield that indicates that the second PHY data unit includes one or more PHY midambles, ii) a short training field (STF) for automatic gain control (AGC) training and synchronization at a receiver, and iii) one or more long training fields (LTFs) for determining a channel estimate at the receiver,

generating a data payload of the second PHY data unit having i) a set of OFDM symbols, among the second plurality of OFDM symbols, and ii) one or more PHY midambles, wherein each of the one or more PHY midambles includes one or more LTFs for determining an updated channel estimate; and

wherein the one or more IC devices are further configured to transmit the second PHY data unit via the wireless communication channel.

13. The apparatus of claim 12, wherein the one or more IC devices are further configured to generate the one or more midambles so that each of the one or more midambles includes an STF for AGC retraining at the receiver.

14. The apparatus of claim 12, wherein the one or more IC devices are further configured to:

generate each PHY midamble to include a respective signal field.

15. The apparatus of claim 12, wherein:

the one or more midambles includes a first-occurring midamble in the data payload of the second PHY data unit;

the first-occurring midamble is spaced apart from the second PHY preamble by N_d OFDM symbols;

when the one or more midambles includes multiple midambles, each pair of adjacent midambles in the data payload are spaced apart by N_d OFDM symbols; and

N_d is an integer greater than one.

16. The apparatus of claim 15, wherein:

the one or more midambles is a plurality of midambles;

the plurality of midambles includes a second-occurring midamble in the data payload of the second PHY data unit; and

the second-occurring midamble is spaced apart from the first-occurring midamble by N_d OFDM symbols.

17. The apparatus of claim 16, wherein:

the plurality of midambles includes a third-occurring midamble in the data payload of the second PHY data unit; and

the third-occurring midamble is spaced apart from the second-occurring midamble by N_d OFDM symbols.

18. The apparatus of claim 15, wherein the one or more IC devices are further configured to:

generate the signal field in the second PHY preamble to indicate N_d.

19. The apparatus of claim 18, wherein the one or more IC devices are further configured to:

select N_d from a set of predefined integer values.

20. The apparatus of claim 19, wherein:

wherein the set of predefined integer values consists of two predefined integer values.

21. The apparatus of claim 12, wherein:

a number of LTFs in each PHY midamble varies depending on a number of spatial streams via which the second PHY data unit is transmitted.

22. The apparatus of claim 12, wherein generating the one or more PHY midambles includes, for each PHY midamble:

generating the one or more LTFs using a channel training matrix.

23. The apparatus of claim 12, wherein the network interface device comprises:

a media access control (MAC) processing unit implemented on the one or more IC devices; and

a PHY processing unit implemented on the one or more IC devices and coupled to the MAC processing unit;

wherein the PHY processing unit is configured to;

generate the first PHY data unit, and

generate the second PHY data unit.

24. The apparatus of claim 23, wherein the PHY processing unit comprises:

a midamble generator implemented on the one or more IC devices, the midamble generator configured to generate the one or more PHY midambles.

25. The apparatus of claim 23, wherein the PHY processing unit comprises:

one or more transceivers implemented on the one or more IC devices.

26. The apparatus of claim 25, further comprising:

one or more antennas coupled to the one or more transceivers.