Signal Identification of Differential STBC-OFDM System

Abstract

Abstract

Blind recognition of communication parameters is a research topic of high importance for both military and civilian communication systems. Signal identification has emerged as an enabling technology for intelligent wireless communication systems with applications in military and commercial fields. Several identification algorithms are proposed for multiple antenna (MA) systems with multicarrier (MC) transmissions. The previously investigations are mostly limited to space-time block code (STBC) systems and space frequency block coding (SFBC) with MC transmissions. In this paper, DSTBC identification for MA orthogonal frequency-division multiplexing (OFDM) transmission is done to determine if the received signal is AL-DSTBC or SM-DSTBC. Analytical expressions for the time-domain properties of the Alamouti (AL) and spatial multiplexing (SM) STBC-OFDM signals available are used as the basis of the identification process. The algorithm has two steps. The first step is to estimate the cross-correlation function of pairs of signals received from different antennas and the second step uses a false-alarm based test for decision making. The advantage of using this algorithm is that it avoids the need for a priori knowledge of the modulation format, channel coefficients, signal-to- noise ratio (SNR) value, and the starting time of OFDM symbols. The probability of correct identification is analyzed for various transmission parameters.

Keywords: Blind signal identification, Space frequency Block codes, OFDM, Alamouti codes, Spatial multiplexing, DSTBC