US 7,599,332 B2 · Modified preamble structure for IEEE 802.11a extensions to allow for coexistence and interoperability between 802.11a devices and higher data rate, MIMO or otherwise extended devices

Abstract

A modified preamble is used by extended devices that operate at higher rates, MIMO or other extensions relative to strict 802.11a-compliant devices. The extended devices might use multiple antenna techniques (MIMO), where multiple data streams are multiplexed spatially and/or multi-channel techniques, where an extended transmitter transmits using more than one 802.11a channel at a time. Such extensions to IEEE 802.11a can exist in extended devices. The modified preamble is usable for signaling, to legacy devices as well as extended devices, to indicate capabilities and to cause legacy devices or extended devices to defer to other devices such that the common communication channel is not subject to unnecessary interference. The modified preamble is also usable for obtaining MIMO channel estimates and/or multi-channel estimates. The modified preamble preferably includes properties that facilitate detection of conventional and/or extended modes (“mode detection”) and provides some level of coexistence with legacy IEEE 802.11a devices.

Claims27

Dependent claims

A method for transmitting a training sequence, the method comprising:

transmitting from at least first and second transmit antennas of a wireless communications system at least first and second preambles configured respectively for transmission from said at least first and second transmit antennas, each of the at least first and second preambles further comprising:
a short training sequence field;
a guard interval field;
a long training sequence field;
and
a signal field;
wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;
wherein the long training sequence field of the second preamble has a cyclic shift;
and wherein the signal field of the second preamble has a cyclic shift with respect to the signal of the first preamble.

6 more elements

A method for transmitting a training sequence comprising first, second, third, and fourth preambles, the method comprising:

transmitting from first, second, third, and fourth transmit antennas of a wireless communications system a training sequence configured for transmission from said first, second, third and fourth transmit antennas of, each of the first, second, third, and fourth preambles further comprising:
a short training sequence field having a duration of 8 μsec;
a guard interval field having a duration of 1.6 μsec;
a long training sequence field having a duration of 6.4 μsec;
and
a signal field having a duration of 4 μsec;
wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble, wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the short training sequence field of the fourth preamble has a cyclic shift of 600 nsec with respect to the short training sequence field of the first preamble;
wherein the long training sequence field of the second preamble has a cyclic shift of 800 nsec with respect to the long training sequence field of the first preamble, wherein the long training sequence field of the third preamble has a cyclic shift of 1600 nsec with respect to the long training sequence field of the first preamble, and wherein the long training sequence field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the long training sequence field of the first preamble;
wherein the signal field of the second preamble has a cyclic shift of 800 nsec with respect to the signal field of the first preamble, wherein the signal field of the third preamble has a cyclic shift of 1600 nsec with respect to the signal field of the first preamble, and wherein the signal field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the signal field of the first preamble;
and wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, third, and fourth preambles has a zero value.

7 more elements

A method for transmitting a training sequence, the method comprising:

transmitting from at least first and second transmit antennas of a wireless communications system at least first and second preambles configured for transmission from said first and second transmit antennas, each of the first and second preambles further comprising:
a short training sequence field;
first and second guard interval fields;
a signal field;
first long training sequence field disposed between the first and second guard interval fields;
and
second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;
wherein the first long training sequence field of the second preamble has a cyclic shift with respect to the first long training sequence field of the first preamble;
wherein the second long training sequence field of the second preamble has a cyclic shift with respect to the second long training sequence field of the first preamble;
and wherein the signal field of the second preamble has a cyclic shift with respect to the signal field of the first preamble.

7 more elements

An apparatus comprising:

a processor operative to generate a training sequence comprising first, second, third, and fourth preambles configured for transmission from first, second, third and fourth transmit antennas of a wireless communication system, each of the first, second, third, and fourth preambles further comprising:
a short training sequence field having a duration of 8 μsec;
a guard interval field having a duration of 1 .6 μsec;
a long training sequence field having a duration of 6.4 μsec;
and a signal field having a duration of 4 μsec;
wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble, wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the short training sequence field of the fourth preamble has a cyclic shift of 600 nsec with respect to the short training sequence field of the first preamble;
wherein the long training sequence field of the second preamble has a cyclic shift of 800 nsec with respect to the long training sequence field of the first preamble, wherein the long training sequence field of the third preamble has a cyclic shift of 1600 nsec with respect to the long training sequence field of the first preamble, and wherein the long training sequence field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the long training sequence field of the first preamble;
wherein the signal field of the second preamble has a cyclic shift of 800 nsec with respect to the signal field of the first preamble, wherein the signal field of the third preamble has a cyclic shift of 1600 nsec with respect to the signal field of the first preamble, and wherein the signal field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the signal field of the first preamble;
and wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, third, and fourth preambles has a zero value.

6 more elements

An apparatus comprising:

a processor operative to generate a training sequence comprising at least first and second preambles configured respectively for transmission from at least first and second transmit antennas of a wireless communication system, each of the first and second preambles further comprising:
a short training sequence field;
first and second guard interval fields;
a signal field;
first long training sequence field disposed between the first and second guard interval fields;
and
second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;
wherein the first long training sequence field of the second preamble has a cyclic shift with respect to the first long training sequence field of the first preamble;
wherein the second long training sequence field of the second preamble has a cyclic shift with respect to the second long training sequence field of the first preamble;
and wherein the signal field of the second preamble has a cyclic shift with respect to the signal field of the first preamble.

7 more elements

A wireless communication device comprising:

a plurality of transmit antennas;
and
means for generating a training sequence comprising first, second, third, and fourth preambles configured for transmission from first, second, third and fourth of said transmit antennas, each of the first, second, third, and fourth preambles further comprising:
a short training sequence field having a duration of 8 μsec;
a guard interval field having a duration of 1 .6 μsec;
a long training sequence field having a duration of 6.4 μsec;
and a signal field having a duration of 4 μsec;
wherein the short training sequence field of the second preamble has a cyclic shift of 200 nsec with respect to the short training sequence field of the first preamble, wherein the short training sequence field of the third preamble has a cyclic shift of 400 nsec with respect to the short training sequence field of the first preamble, and wherein the short training sequence field of the fourth preamble has a cyclic shift of 600 nsec with respect to the short training sequence field of the first preamble;
wherein the long training sequence field of the second preamble has a cyclic shift of 800 nsec with respect to the long training sequence field of the first preamble, wherein the long training sequence field of the third preamble has a cyclic shift of 1600 nsec with respect to the long training sequence field of the first preamble, and wherein the long training sequence field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the long training sequence field of the first preamble;
wherein the signal field of the second preamble has a cyclic shift of 800 nsec with respect to the signal field of the first preamble, wherein the signal field of the third preamble has a cyclic shift of 1600 nsec with respect to the signal field of the first preamble, and wherein the signal field of the fourth preamble has a cyclic shift of 2400 nsec with respect to the signal field of the first preamble;
and wherein only the DC tone of the tones disposed in the long training sequence field of each of the first, second, third, and fourth preambles has a zero value.

8 more elements

A wireless communication device comprising:

a plurality of transmit antennas;
and
means for generating a training sequence comprising at least first and second preambles configured respectively for transmission from at least first and second if said transmit antennas of a wireless communication system, each of the first and second preambles further comprising:
a short training sequence field;
first and second guard interval fields;
a signal field;
first long training sequence field disposed between the first and second guard interval fields;
and
second long training sequence field disposed between the second guard interval field and the signal field, wherein the short training sequence field of the second preamble has a cyclic shift with respect to the short training sequence field of the first preamble;
wherein the first long training sequence field of the second preamble has a cyclic shift with respect to the first long training sequence field of the first preamble;
wherein the second long training sequence field of the second preamble has a cyclic shift with respect to the second long training sequence field of the first preamble;
and wherein the signal field of the second preamble has a cyclic shift with respect to the signal field of the first preamble.

9 more elements

Dependencies are inferred from the claim text.

Modified preamble structure for IEEE 802.11a extensions to allow for coexistence and interoperability between 802.11a devices and higher data rate, MIMO or otherwise extended devices

Life of this patent

Modified preamble structure for IEEE 802.11a extensions to allow for coexistence and interoperability between 802.11a devices and higher data rate, MIMO or otherwise extended devices

Life of this patent

Abstract

Claims27