SummaryWith wireless communications in high‐mobility environment becoming popular, this poses a big challenge for communication systems based on the comb‐pilot OFDM, such as IEEE 802.11p, since it has not the enough pilots to estimate the time‐ and frequency‐selective channel accurately. In this paper, several comb‐pilot schemes and three comb‐pilot design rules are proposed to meet the Nyquist criterion for sampling the vehicle‐to‐vehicle (V2V) channel and the requirements of second‐order statistic of V2V channel. Based on the proposed pilot schemes, an iterative channel estimation method from the CE‐BEM model is proposed, together with three ICI cancellation methods. After thorough simulation, the effectiveness of the comb‐pilot design rules, the proposed channel estimation method, and intercarrier interference (ICI) cancellation methods is verified. Compared with other channel estimation methods, the proposed method performs better. The simulation results also reveal that the channel order L+1 has a great impact on the performance of the comb‐pilot OFDM system.

Abstracr-This paper makes a research on the fundamental principle of digital modulation and frequency conversion in broad band digital broadcasting-terrestrial TV ( BDB-T ) system. Diiferent from conventional down-conversion technique, this paper proposes a new digital down-conversion model utilizing Hilbert transform and a method eliminating the AID DC offset in this model is also proposed. The correspondent FPGA hardware though testing process in HDTV prototype proves the efficiency and good performance of the model and the new method.Index Terms-High Definition TV, coded orthogonal frequency division multipllexing, digital frequency conversion, field programmable gate array