Method and system for compromise greenfield preambles for 802.11n
View Patent ↗Aspects of the invention described herein may enable a greenfield access mode in IEEE 802.11n WLAN systems in comparison to an alternative approach that may not provide greenfield access. The utilization of greenfield access may reduce the portion of time required to transmit data due to overhead comprising preamble fields and header fields. This may enable higher data throughput rates to be achieved. This may further enable more robust transmission of data by enabling comparable data rates to be maintained while reducing the coding rate of encoded transmitted data. The reduction of the coding rate may enable comparable data rates to be maintained for transmission via RF channels characterized by lower SNR while still achieving desired target levels of packet error rates. In another aspect of the invention, mixed mode access may be achieved while reducing the portion of time required for transmitting data due to overhead.
1. An apparatus, comprising:
at least one processor and/or circuit to generate a signal adapted for Greenfield access, wherein:
the signal including, for a first spatial stream, a first HT short training field (STF) followed by a first single HT long training field (LTF) followed by a first signal (SIG) field followed by a first plurality of HT LTFs followed by a first data field;
the signal also including, for a second spatial stream, a second STF, a second single HT LTF, a second SIG field, and a second plurality of HT LTFs; and
the first STF and the second STF each having a respective 8 micro-sec duration;
the single HT LTF and the second HT LTF each having a respective 8 micro-sec duration;
the first SIG field and the second SIG field each having a respective 8 micro-sec duration; and
the first plurality of HT LTFs being orthonormal having a corresponding plurality of single symbols and having a respective 4 micro-sec duration and the second plurality of HT LTFs being orthonormal having a corresponding plurality of single symbols and having a respective 4 micro-sec duration; and
at least one communication interface to transmit the signal to at least one additional apparatus via a plurality of transmit antennas to a device having a plurality of receive antennas;
wherein:
the second STF being a cyclic diversity delay shifted version of the first STF;
the second single HT LTF being a cyclic diversity delay shifted version of the first single HT LTF;
the second SIG field being a cyclic diversity delay shifted version of the first SIG field; and
at least one of the second plurality of HT LTFs being a cyclic diversity delay shifted version of at least one of the first plurality of HT LTFs.
2. The apparatus of claim 1 , wherein:
the first SIG field or the second SIG field including at least one field to indicate at least one of a number of spatial streams, a number of transmit antennas, a bandwidth, a coding rate, an error correcting code type, a constellation type, a length, and a cyclic redundancy check (CRC) corresponding to the signal.
3. The apparatus of claim 1 , wherein:
the apparatus being a transmitter communication device;
the at least one additional apparatus being a receiver communication device to employ the signal for at least one of signal detection, automatic gain control (AGC) for low noise amplification circuitry within the receiver communication device, diversity selection performed by rake receiver circuitry within the receiver communication device, coarse frequency offset estimation, and timing synchronization.
4. The apparatus of claim 1 , wherein:
the apparatus being a wireless station (STA) and the at least one additional apparatus being an access point (AP); or
the apparatus being an AP and the at least one additional apparatus being a STA.
5. An apparatus, comprising:
at least one processor and/or circuit to generate a signal adapted for Greenfield access, wherein the signal including, for at least one spatial stream, a HT short training field (STF) followed by a single HT long training field (LTF) followed by a signal (SIG) field followed by a plurality of HT LTFs having a corresponding plurality of single symbols followed by a data field wherein the plurality of HT LTFs are orthonormal; and
at least one communication interface to transmit the signal to at least one additional apparatus via a plurality of transmit antennas to a device having a plurality of receive antennas;
wherein: the STF, the single HT LTF, the SIG field, and the plurality of HT LTFs being a first STF, a first single HT LTF, a first SIG field, and a first plurality of HT LTFs, respectively, for a first spatial stream; and
the signal also including, a second STF, a second single HT LTF, a second SIG field, and a second plurality of HT LTFs, respectively, for a second spatial stream;
and wherein, at least one of:
the second STF being a cyclic diversity delay shifted version of the first STF;
the second single HT LTF being a cyclic diversity delay shifted version of the first single HT LTF;
the second SIG field being a cyclic diversity delay shifted version of the first SIG field; and
at least one of the second plurality of HT LTFs being a cyclic diversity delay shifted version of at least one of the first plurality of HT LTFs.
6. The apparatus of claim 5 , wherein:
the STF having an 8 micro-sec duration;
the single HT LTF having an 8 micro-sec duration;
the SIG field having an 8 micro-sec duration; and
each of the plurality of HT LTFs having a respective 4 micro-sec duration.
7. The apparatus of claim 5 , wherein:
the SIG field including at least one field to indicate at least one of a number of spatial streams, a number of transmit antennas, a bandwidth, a coding rate, an error correcting code type, a constellation type, a length, and a cyclic redundancy check (CRC) corresponding to the signal.
8. The apparatus of claim 5 , wherein:
the apparatus being a transmitter communication device;
the at least one additional apparatus being a receiver communication device to employ the signal for at least one of signal detection, automatic gain control (AGC) for low noise amplification circuitry within the receiver communication device, diversity selection performed by rake receiver circuitry within the receiver communication device, coarse frequency offset estimation, and timing synchronization.
9. The apparatus of claim 5 , wherein:
the apparatus being a wireless station (STA) and the at least one additional apparatus being an access point (AP); or
the apparatus being an AP and the at least one additional apparatus being a STA.
10. A method for operating a communication device, the method comprising:
operating at least one processor and/or circuit of the communication device to generate a signal adapted for Greenfield access, wherein the signal including, for at least one spatial stream, a HT short training field (STF) followed by a single HT long training field (LTF) followed by a signal (SIG) field followed by a plurality of HT LTFs having a corresponding plurality of single symbols followed by a data field, wherein the plurality of HT LTFs are orthonormal; and
via at least one communication interface of the communication device, transmitting the signal via a plurality of transmit antennas to at least one additional communication device having a plurality of receive antennas
wherein:
the STF, the single HT LTF, the SIG field, and the plurality of HT LTFs being a first STF, a first single HT LTF, a first SIG field, and a first plurality of HT LTFs, respectively, for a first spatial stream; and
the signal also including, a second STF, a second single HT LTF, a second SIG field, and a second plurality of HT LTFs, respectively, for a second spatial stream;
and wherein, at least one of:
the second STF being a cyclic diversity delay shifted version of the first STF;
the second single HT LTF being a cyclic diversity delay shifted version of the first single HT LTF;
the second SIG field being a cyclic diversity delay shifted version of the first SIG field; and
at least one of the second plurality of HT LTFs being a cyclic diversity delay shifted version of at least one of the first plurality of HT LTFs.
11. The method of claim 10 , wherein:
the STF having an 8 micro-sec duration;
the single HT LTF having an 8 micro-sec duration;
the SIG field having an 8 micro-sec duration; and
each of the plurality of HT LTFs having a respective 4 micro-sec duration.
12. The method of claim 10 , wherein:
the SIG field including at least one field to indicate at least one of a number of spatial streams, a number of transmit antennas, a bandwidth, a coding rate, an error correcting code type, a constellation type, a length, and a cyclic redundancy check (CRC) corresponding to the signal.
13. The method of claim 10 , wherein:
the communication device being a wireless station (STA) and the at least one additional communication device being an access point (AP); or
the communication device being an AP and the at least one additional communication device being a STA.