Patent ID: 7983236

Claim:
A method comprising: arranging data for transmission in a frame structure, the frame structure comprising a series of subframes, each subframe comprising a plurality of frequency-divided sub-carriers, each sub-carrier comprising a plurality of time-divided symbol positions; determining pilot sequences for aiding a receiver in estimating a channel comprising the sub-carriers over which the data is to be transmitted; in each subframe, disposing a pilot sequence for a first transmit antenna in a first of the plurality of symbol positions only in every (2*N) th one of the sub-carriers, where N is equal to three or four; in each subframe, disposing a pilot sequence for a second transmit antenna in the first symbol position only in every (2*N)' h one of the sub-carriers, wherein the pilot sequences for the first transmit antenna that are in the first symbol position are in different sub-carriers than the pilot sequences for the second transmit antenna that are in the first symbol position, and wherein the subcarriers in which are disposed the pilot sequences for the first transmit antenna that are in the first symbol position are not adjacent to the subcarriers in which are disposed the pilot sequences for the second transmit antenna that are in the first symbol position; and transmitting the frame comprising the data and disposed pilot sequences over the channel from the first and the second transmit antennas.