Preamble extensions

Abstract

Systems and/or methods for communication that generate a plurality of spatial streams are disclosed. Each of the spatial streams comprises a plurality of symbols. At least a portion of a training sequence is distributed across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams.

1 . An apparatus for wireless communications, comprising:
 at least one processor configured to,
 generate a plurality of spatial streams, wherein each of the spatial streams comprises a plurality of symbols, and 
 distribute at least a portion of a training sequence across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams; and 
   a memory coupled with the at least one processor.   
     
     
         2 . The apparatus of  claim 1 , wherein the at least one processor is further configured to distribute a further portion of the training sequence into a third symbol in a third one of the spatial streams. 
     
     
         3 . The apparatus of  claim 1 , wherein each of the first and second symbols comprises a plurality of subcarriers, the processing system being further configured to distribute said at least a portion of the training sequence across different subcarriers in the first and second symbols. 
     
     
         4 . The apparatus of  claim 1 , wherein the at least one processor is further configured to cyclically delay the portion of the training sequence in the first symbol. 
     
     
         5 . The apparatus of  claim 1 , wherein the first one of the symbols includes a plurality of subcarriers carrying a signal, the processing system being further configured to multiply the signal carried by the subcarriers by the portion of the training sequence in the first symbol. 
     
     
         6 . The apparatus of  claim 1 , wherein the first symbol includes a plurality of in-band and out-of-band subcarriers, the processing system being further configured to distribute the portion of the training sequence in the first symbol across the in-band subcarriers. 
     
     
         7 . The apparatus of  claim 6 , wherein the at least one processor is further configured to attenuate the out-of-band subcarriers. 
     
     
         8 . The apparatus of  claim 1 , wherein the at least one processor is further configured to distribute a further portion of the training sequence into another symbol in the first one of the spatial streams that temporally follows the first symbol. 
     
     
         9 . The apparatus of  claim 1 , wherein the at least one processor is further configured to distribute a remaining portion of the training sequence into one or more symbols in the first one of the spatial streams that temporally follow the first symbol such that all tones of the training sequence are included in the first one of the spatial streams. 
     
     
         10 . The apparatus of  claim 9 , wherein the training sequence is distributed across eight symbols in the first one of the spatial streams. 
     
     
         11 . The apparatus of  claim 9 , wherein the training sequence comprises a Walsh encoded training sequence. 
     
     
         12 . The apparatus of  claim 1 , wherein the at least one processor is further configured to distribute the portion of the training sequence in the first symbol into another symbol on a third one of the streams that temporally follows the first symbol. 
     
     
         13 . The apparatus of  claim 1 , wherein the at least one processor is further configured to modulate at least one of the plurality of symbols with a spoof modulation scheme. 
     
     
         14 . The apparatus of  claim 1 , wherein the at least one processor is further configured to:
 modulate one of the plurality of symbols in the first one of the spatial streams with a first modulation scheme, and   modulate another one of the plurality of symbols in the first one of the spatial streams with a second modulation scheme that is different from the first modulation scheme.   
     
     
         15 . The apparatus of  claim 1 , wherein each of the spatial streams comprises at least one symbol comprising information indicating a length of data and a modulation scheme, and wherein said information is different for at least two of the spatial streams. 
     
     
         16 . The apparatus of  claim 1 , wherein the at least one processor is further configured to:
 distribute a further portion of the training sequence into a third symbol in the first one of the spatial streams that temporally follows the first symbol, and   distribute the portion of the training sequence in the first symbol into a fourth symbol in the first one of the spatial streams that temporally follows the third symbol.   
     
     
         17 . A method for communications, comprising:
 generating a plurality of spatial streams, wherein each of the spatial streams comprises a plurality of symbols; and   distributing at least a portion of a training sequence across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams.   
     
     
         18 . The method of  claim 17  further comprising distributing a further portion of the training sequence into a third symbol in a third one of the spatial streams. 
     
     
         19 . The method of  claim 17 , wherein each of the first and second symbols comprises a plurality of subcarriers, and said at least a portion of the training sequence are distributed across different subcarriers in the first and second symbols. 
     
     
         20 . The method of  claim 17  further comprising cyclically delaying the portion of the training sequence in the first symbol. 
     
     
         21 . The method of  claim 17 , wherein the first one of the symbols includes a plurality of subcarriers carrying a signal, the method further comprising multiplying the signal carried by the subcarriers by the portion of the training sequence in the first symbol. 
     
     
         22 . The method of  claim 17 , wherein the first symbol includes a plurality of in-band and out-of-band subcarriers, and the portion of the training sequence in the first symbol is distributed across the in-band subcarriers. 
     
     
         23 . The method of  claim 22  further comprising attenuating the out-of-band subcarriers. 
     
     
         24 . The method of  claim 17  further comprising distributing a further portion of the training sequence into another symbol in the first one of the spatial streams that temporally follows the first symbol. 
     
     
         25 . The method of  claim 17  further comprising distributing a remaining portion of the training sequence into one or more symbols in the first one of the spatial streams that temporally follow the first symbol such that all tones of the training sequence are included in the first one of the spatial streams. 
     
     
         26 . The method of  claim 25 , wherein the training sequence is distributed across eight symbols in the first one of the spatial streams. 
     
     
         27 . The method of  claim 25 , wherein the training sequence comprises a Walsh encoded training sequence. 
     
     
         28 . The method of  claim 17  further comprising distributing the portion of the training sequence in the first symbol into another symbol on a third one of the streams that temporally follows the first symbol. 
     
     
         29 . The method of  claim 17  further comprising modulating at least one of the plurality of symbols with a spoof modulation scheme. 
     
     
         30 . The method of  claim 17  further comprising modulating one of the plurality of symbols in the first one of the spatial streams with a first modulation scheme, and modulating another one of the plurality of symbols in the first one of the spatial streams with a second modulation scheme that is different from the first modulation scheme. 
     
     
         31 . The method of  claim 17 , wherein each of the spatial streams comprises at least one symbol comprising information indicating a length of data and a modulation scheme, and wherein said information is different for at least two of the spatial streams. 
     
     
         32 . The method of  claim 17  further comprising distributing a further portion of the training sequence into a third symbol in the first one of the spatial streams that temporally follows the first symbol, and distributing the portion of the training sequence in the first symbol into a fourth symbol in the first one of the spatial streams that temporally follows the third symbol. 
     
     
         33 . An apparatus for communications, comprising:
 means for generating a plurality of spatial streams, wherein each of the spatial streams comprises a plurality of symbols; and   means for distributing at least a portion of a training sequence across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams.   
     
     
         34 . A computer-program product for wireless communication, comprising:
 a machine-readable medium encoded with instructions executable to:
 generate a plurality of spatial streams, wherein each of the spatial streams comprises a plurality of symbols; and 
 distribute at least a portion of a training sequence across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams. 
   
     
     
         35 . An access point, comprising:
 a wireless network adapter configured to support a backhaul connection for a peer node to a network; and   a processing system configured to generate a plurality of spatial streams, wherein each of the spatial streams comprises a plurality of symbols, the processing system being further configured to distribute at least a portion of a training sequence across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams.   
     
     
         36 . An access terminal, comprising:
 a processing system configured to receive a plurality of spatial streams, wherein each of the spatial streams comprises a plurality of symbols, and wherein at least a portion of a training sequence is distributed across a first symbol in a first one of the spatial streams and a second symbol in a second one of the spatial streams; and   a user interface supported by the processing system.   
     
     
         37 . An apparatus for wireless communications, comprising:
 at least one processor configured to,
 generate a preamble to be transmitted to a plurality of stations, 
   the preamble comprising a sequence of symbols,
 transmit a first part of the preamble in a non-beamformed fashion, and 
 transmit a second part of the preamble using beamforming; and 
   a memory coupled with the at least one processor.   
     
     
         38 . The apparatus of  claim 37 , wherein the first part of the preamble comprises a mixed mode preamble up to a second symbol of a high throughput (HT) signal field. 
     
     
         39 . The apparatus of  claim 37 , wherein the processor is further configured to transmit steered Multi-User Multi-Input Multi-Output (MU-MIMO) data after the preamble. 
     
     
         40 . The apparatus of  claim 37 , wherein the second part of the preamble comprises a short training field used for automatic gain control (AGC) setting by at least one of the stations. 
     
     
         41 . The apparatus of  claim 37 , wherein the second part of the preamble consists of a second symbol comprising a training field which temporally follows the first symbol. 
     
     
         42 . The apparatus of  claim 41 , wherein the training field is used to estimate the channel needed to demodulate the symbols following the training field 
     
     
         43 . The apparatus of  claim 41 , wherein the symbols following the training field comprise a signal field 
     
     
         44 . The apparatus of  claim 43 , wherein the signal field is different for at least two of the STAs 
     
     
         45 . The apparatus of  claim 39 , wherein the length and MCS of the transmission in the signal field present in a high throughput (HT) part of a mixed mode preamble is chosen to convey a duration of a longest of the steered MU-MIMO transmissions which follow the preamble. 
     
     
         46 . The apparatus of  claim 43 , wherein the signal field is used for mode detection using a specific modulation scheme 
     
     
         47 . The apparatus of  claim 46 , wherein mode detection comprises determining whether a transmission is in accordance with IEEE 802.11n or IEEE 802.11ac. 
     
     
         48 . The apparatus of  claim 46 , wherein the specific modulation scheme involves inverting pilots relative to the data 
     
     
         49 . The apparatus of  claim 46 , wherein the specific modulation scheme involves rotating BPSK modulation symbols. 
     
     
         50 . The apparatus of  claim 41 , wherein the symbols comprise a single symbol modulated using QPSK. 
     
     
         51 . A method apparatus for wireless communications, comprising:
 generating a preamble to be transmitted to a plurality of stations, the preamble comprising a sequence of symbols;   transmitting a first part of the preamble in a non-beamformed fashion; and   transmitting a second part of the preamble using beamforming.   
     
     
         52 . The method of  claim 51 , wherein the first part of the preamble comprises a mixed mode preamble up to a second symbol of a high throughput (HT) signal field. 
     
     
         53 . The method of  claim 51 , further comprising transmitting steered Multi-User Multi-Input Multi-Output (MU-MIMO) data after the preamble. 
     
     
         54 . The method of  claim 51 , wherein the second part of the preamble comprises a short training field used for automatic gain control (AGC) setting by at least one of the stations. 
     
     
         55 . The method of  claim 51 , wherein the second part of the preamble consists of a second symbol comprising a training field which temporally follows the first symbol. 
     
     
         56 . The method of  claim 55 , wherein the training field is used to estimate the channel needed to demodulate the symbols following the training field. 
     
     
         57 . The method of  claim 55 , wherein the symbols following the training field comprise a signal field. 
     
     
         58 . The method of  claim 57 , wherein the signal field is different for at least two of the STAs. 
     
     
         59 . The method of  claim 53 , wherein the length and MCS of the transmission in the signal field present in a high throughput (HT) part of a mixed mode preamble is chosen to convey a duration of a longest of the steered MU-MIMO transmissions which follow the preamble. 
     
     
         60 . The method of  claim 57 , where the signal field is used for mode detection using a specific modulation scheme. 
     
     
         61 . The method of  claim 60 , wherein mode detection comprises determining whether a transmission is in accordance with IEEE 802.11n or IEEE 802.11ac. 
     
     
         62 . The method of  claim 60 , wherein the specific modulation scheme involves inverting pilots relative to the data 
     
     
         63 . The method of  claim 60 , wherein the specific modulation scheme involves rotating BPSK modulation symbols. 
     
     
         64 . The method of  claim 55 , wherein the symbols comprise a single symbol modulated using QPSK. 
     
     
         65 . An apparatus for communications, comprising:
 means for generating a preamble to be transmitted to a plurality of stations, the preamble comprising a sequence of symbols;   means for transmitting a first part of the preamble in a non-beamformed fashion; and   means for transmitting a second part of the preamble using beamforming.   
     
     
         66 . A computer-program product for wireless communication, comprising:
 a machine-readable medium encoded with instructions executable to:
 generate a preamble to be transmitted to a plurality of stations, 
   the preamble comprising a sequence of symbols;
 transmit a first part of the preamble in a non-beamformed fashion; and 
 transmit a second part of the preamble using beamforming 
   
     
     
         67 . An access point, comprising:
 a wireless network adapter configured to support a backhaul connection for a peer node to a network; and   a processing system configured to generate a preamble to be transmitted to a plurality of stations, the preamble comprising a sequence of symbols, transmit a first part of the preamble in a non-beamformed fashion, and transmit a second part of the preamble using beamforming.   
     
     
         68 . An access terminal, comprising:
 a processing system configured to receive a preamble transmitted to a plurality of access terminals, the preamble comprising a sequence of symbols, wherein a first part of the preamble is transmitted in a non-beamformed fashion and a second part of the preamble is transmitted using beamforming; and   a user interface supported by the processing system.