In Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) systems, additional very low-rate data can be transmitted by modulating the amplitude and polarity of the transmitter identification (TxID) signal. Although the additional data transmission scheme offers reliable transmission and has a very large coverage area, it has a limitation on the data rate. In this paper, we propose a novel additional data transmission scheme based on the TxID sequences of the ATSC DTV system and Walsh modulation. The proposed scheme not only increases the data rate significantly, but also offers a virtually identical coverage area compared to a conventional scheme.Keywords: ATSC DTV, Kasami sequence, transmitter identification, Walsh sequence. Manuscript received May 19, 2011; revised Sept. 9, 2011; accepted Oct. 19, 2011
I. IntroductionIn single-frequency networks (SFNs) for the Advanced Television Systems Committee (ATSC) terrestrial digital television (DTV) systems, interference is inevitably induced by the multiple transmitters and/or repeaters using the same frequency, and thus the performance of DTV systems is degraded [1], [2]. This problem can be solved by adjusting the transmit power and timing of each transmitter and/or repeater after detecting channel profiles in the SFNs and estimating the individual reception power from each transmitter and/or repeater [3], [4]. To facilitate the interference manipulation, the ATSC Standard A/110 introduces transmitter identification (TxID) signals with very low power, which are embedded in the DTV signal to be transmitted from each transmitter and repeater [1].On the other hand, in [5], [6], a very low-rate data transmission scheme that provides robustness and extremely large coverage was developed by modulating the amplitude and polarity of the TxID signal. However, the achievable data rate of the scheme in [5], [6] is at most up to a few hundred bits per second (bps), for example, 210 bps with 4-level pulse amplitude modulation (4-PAM).In this paper, we propose a novel data transmission scheme using TxID and Walsh sequences in ATSC DTV systems. The proposed scheme transmits data bits using a Walsh sequence and its polarity. The proposed scheme significantly enhances the data rate compared to the conventional scheme. Also, the performance of the proposed scheme is analyzed and evaluated.The remainder of this paper is organized as follows. In section II, system models and conventional data transmission schemes are briefly presented. In section III, the proposed scheme is described, and in section IV, a performance analysis is theoretically performed. In section V, numerical results are
II. System Models 1. TxID Signal TransmissionThe ATSC Standard A/110 introduces a particular form of pseudo-random noise sequences, referred to as Kasami sequences, to identify multiple transmitters and/or repeaters in SFNs [1]. The Kasami sequences are binary sequences of length 2 n −1, where n is an even integer. They comprise a large set, denoted as K L , and a small s...