Provided by: Springer
Date Added: Jun 2011
The authors have addressed the design of optimal preamble as well as suboptimal pilot symbols for channel estimation in OFDM systems with null subcarriers. First, they have formulated the channel estimate MSE minimization problem for a determined subcarrier set as an SDP, then they have employed convex optimization techniques to obtain near optimal power distribution to a given subcarrier set. Design examples consistent with IEEE 802.11a standard show that in terms of channel estimate MSE, the long OFDM preamble with equi-powered active subcarriers is nearly optimal.