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

摘要

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.

主权项

1. A method for transmitting a training sequence, the method comprising:
transmitting at least first and second preambles configured for transmission from first and second transmit antennas of a wireless communication system, wherein the first preamble comprises: a short training sequence field; a long training sequence field defined by the odd tones of a legacy long training sequence field; a guard interval field generated from time-domain representation of the odd tones of the long training sequence; and a signal field defined by the odd tones of a legacy signal field; and wherein the second preamble comprises: a short training sequence field cyclically shifted with respect to the short training field of the first preamble; a long training sequence field defined by the even tones of the legacy long training sequence field; a guard interval field generated from time-domain representation of the long training sequence of the second preamble; and a signal field defined by the even tones of the legacy signal field.