Abstract
This paper addresses a novel Alamouti space-frequency block decoding scheme with discontinuous Doppler diversity (DDoD) and cyclic delay diversity (CDD). We investigate different antenna diversity concepts, which can be applied to orthogonal frequency division multiplexing (OFDM) systems over highly frequency selective channels. The main object of this research is standard compatibility and the effect of simple diversity techniques on the channel fading properties. Therefore, we analyze a receiver in terms of the effective channel transfer function, which leads to the possibility of optimizing diversity. Besides, a novel transceiver using DDoD is proposed, which increases the Doppler spread of the multipath fading channel without causing additional Intercarrier Interference (ICI). Moreover, an efficient Alamouti encoder and decoder based on CDD is proposed, which allows a high reliability and capacity enhancement. In order to evaluate the capability of that, we have implemented this scheme for the second-generation terrestrial video broadcasting (DVB-T2) system over different channels. Furthermore, mathematical analysis and simulation results show the bit error performance of the modified encoding method with these diversity techniques, performs mostly better than the other forms of encoding Alamouti over highly frequency-selective channels such as single frequency networks (SFN). The other advantages of the proposed method are simplicity, flexibility, and standard compatibility.
Highlights
The orthogonal frequency division multiplexing (OFDM) is known as an attractive modulation scheme for high-rate for transforming a frequency selective channel into multiple flat-fading channels [1], [2]
There is a fact to take into account that if the cyclic prefix (CP) length is increased for the delay diversity (DD) scheme, the amount of interference will be huge
We proposed an efficient decoder using the cyclic delay diversity (CDD) and discontinuous Doppler diversity (DDoD) scheme, which enhanced the standard Alamouti decoding and allowed high tolerability of the system in the frequency-selective channels by increasing the diversity
Summary
The orthogonal frequency division multiplexing (OFDM) is known as an attractive modulation scheme for high-rate for transforming a frequency selective channel into multiple flat-fading channels [1], [2]. Combining OFDM modulation with MIMO technology can be used to overcome the multipath distortion and increasing robustness over wireless fading channels [3]–[7] For this propose, the authors in [8] and [9] surveyed Space-time block codes (STBC) as a suitable multiple antenna technology. It needs processing at both transmitter and receiver. In [16], the authors concentrated on turbo equalization receivers for frequency preceded collaborative spatial multiplexing (CSM) MIMO in the uplink of long term evolution advanced (LTE-A) system
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