Patent ID: 8379545

Claim:
A communication method for exchanging channel information between a transmitter and a receiver each including a plurality of antennas, the method comprising: constructing, at the transmitter, a first frame including a first preamble field and a first data field, the first preamble field being generated based on a physical layer protocol and having a first preamble and a second preamble, wherein the first preamble is defined by IEEE802.11a and the second preamble is constructed by a plurality of signals for estimating channel information, and the first data field being generated based on a MAC layer protocol and including a channel information feedback request; transmitting the first frame to the receiver, wherein the first preamble is transmitted from at least one of the plurality of antennas of the transmitter, each of the plurality of signals in the second preamble is transmitted from each of the plurality of antennas of the transmitter, and the first data field is transmitted from the at least one of the plurality of antennas of the transmitter; receiving the first frame at the receiver, wherein the first preamble is received from at least one of the plurality of antennas of the receiver, each of the plurality of signals in the second preamble is received from each of the plurality of antennas of the receiver, and the first data field is received from the at least one of the plurality of antennas of the receiver; estimating channel information, using the second preamble at the receiver; detecting, at the receiver, the channel information feedback request by decoding the first data field based on the estimated channel information; constructing, at the receiver, a second frame including a second preamble field and a second data field, the second preamble field being generated based on the physical layer protocol and having one of a third preamble, the third preamble and a fourth preamble, or the fourth preamble, wherein the third preamble is defined by IEEE802.11a and the fourth preamble is constructed by a plurality of signals, and the second data field being generated based on the MAC layer protocol and including the estimated channel information; transmitting the second frame to the transmitter, each of the plurality of signals in the fourth preamble is transmitted from each of the plurality of antennas of the receiver; and receiving the second frame at the transmitter, the second frame being a response to the first frame.