Providing extended range modes as part of the 802.11n standard
An extended range preamble is disclosed, for transmission between extended range 802.11 n devices. The extended range preamble consists of a high-throughput signal field, in which a modulation coding scheme rate and payload length are specified by the transmitting device. The extended range preamble also includes an expanded preamble, which is adjacent to the high-throughput signal field, and is not understood by non-extended range devices. The modulation coding scheme rate is specified as either one of the rates supported in non-extended range 802.11 devices or as a reserved modulation coding scheme not understood by the non-extended range devices. In either circumstance, the non-extended range device respects the preamble, and thus does not itself attempt a transmission during processing of the preamble.
1. A method, comprising:
transmitting an extended range preamble by a first extended range 802.11n device to a second extended range 802.11n device, wherein the first and second extended range 802.11n devices are part of a wireless neighborhood, the extended range preamble comprising:
a high-throughput signal (HT-SIG) field, comprising a modulation coding scheme (MCS) rate field comprising an MCS rate and a payload length field, wherein the MCS rate is one of seventy-seven rates supported under a legacy standard; and
an expanded preamble; and
snooping the extended range preamble by a non-extended range device in the wireless neighborhood, wherein the non-extended range device:
recognizes the MCS rate as being one of the rates supported under the legacy standard;
waits an appropriate time period based on a payload length specified in the payload length field; and
calculates an incorrect cyclic redundancy check (CRC) of the extended range preamble, due to the non-extended range device not recognizing the expanded preamble;
wherein the extended range 802.11n device transmits the packet to the second extended range 802.11n device during the processing operations performed by the non-extended range device.
2. The method of claim 1 , further comprising:
transmitting the extended range preamble, the expanded preamble therein further comprising:
an expanded range short training field (ER STF);
an expanded range long training field (ER LTF); and
an expanded range signal field (ER SIG).
3. The method of claim 2 , further comprising:
transmitting the extended range preamble, wherein the expanded preamble therein is adjacent to the HT-SIG field.
4. The method of claim 1 , further comprising:
transmitting the extended range preamble, wherein the expanded preamble therein adds 24 to 36 microseconds of transmission time to the extended range preamble.
5. The method of claim 1 , further comprising:
transmitting the extended range preamble, the extended range preamble further comprising:
a high-throughput Green Field short training field (HT-GF-STF); and
a high-throughput long-training field (HT-LTF);
wherein the extended range preamble is a Green Field preamble.
6. The method of claim 1 , further comprising:
transmitting the extended range preamble, the extended range preamble further comprising:
a legacy short training field (L-STF);
a legacy long training field (L-LTF); and
a legacy signal field (L-SIG);
wherein the extended range preamble is a mixed mode preamble.
7. A method, comprising:
transmitting an extended range preamble by a first extended range 802.11n device to a second extended range 802.11n device, wherein the first and second extended range 802.11n devices are part of a wireless neighborhood, the extended range preamble comprising:
a high-throughput signal (HT-SIG) field, comprising a modulation coding scheme (MCS) rate field comprising an MCS rate, wherein the MCS rate is a reserved rate not supported under a legacy standard; and
an expanded preamble;
snooping the extended range preamble by a non-extended range device in the wireless neighborhood, wherein the non-extended range device:
determines that the MCS rate is not one of the reserved rates supported under the legacy standard; and
calculates a signal strength of the extended range preamble;
wherein the extended range 802.11n device transmits the packet to the second extended range 802.11n device without interruption of the non-extended range device if the calculated signal strength equals or exceeds −62 dBm.
8. The method of claim 7 , further comprising:
transmitting the extended range preamble, the expanded preamble therein further comprising:
an expanded range short training field (ER STF);
an expanded range long training field (ER LTF); and
an expanded range signal field (ER SIG).
9. The method of claim 8 , further comprising:
transmitting the extended range preamble, wherein the expanded preamble therein is adjacent to the HT-SIG field.
10. The method of claim 7 , further comprising:
transmitting the extended range preamble, wherein the expanded preamble therein adds 24 to 36 microseconds of transmission time to the extended range preamble.
11. The method of claim 7 , further comprising:
transmitting the extended range preamble, wherein the HT-SIG field therein further comprises a payload length field to indicate a length of a payload following the extended range preamble.
12. The method of claim 7 , further comprising:
transmitting the extended range preamble, the extended range preamble further comprising:
a high-throughput Green Field short training field (HT-GF-STF); and
a high-throughput long-training field (HT-LTF);
wherein the extended range preamble is a Green Field preamble.
13. The method of claim 7 , further comprising:
transmitting the extended range preamble, the extended range preamble further comprising:
a legacy short training field (L-STF);
a legacy long training field (L-LTF); and
a legacy signal field (L-SIG);
wherein the extended range preamble is a mixed mode preamble.
14. A method, comprising:
transmitting an extended range preamble by a first extended range device to a second extended range device in a wireless neighborhood, the extended range preamble comprising:
a high-throughput signal field, indicating a modulation coding scheme rate and a payload length; and
an expanded preamble adjacent to the high-throughput signal field;
snooping the extended range preamble by a non-extended range device in the wireless neighborhood, wherein the non-extended range device performs the following processing operations:
either:
recognizing the modulation coding scheme rate as being one of seventy-seven predefined modulation coding schemes; and
waiting a time period as indicated by the payload length before attempting transmission in the wireless neighborhood; and
calculating a cyclic redundancy check of the extended range preamble, wherein the calculated cyclic redundancy check will be wrong; or
recognizing the modulation coding scheme rate as not being one of seventy-seven predefined modulation coding schemes; and
calculating a signal strength of −62 dBm or greater;
wherein the first extended range device completes the transmission to the second extended range device without interruption of the non-extended range device.