Alamouti-Based Space-Frequency Coding for OFDM

Abstract

We investigate space-frequency block coding for OFDM systems with multiple transmit antennas, where coding is applied in the frequency domain (OFDM carriers) rather than in the time domain (OFDM symbols). In particular we consider Alamouti's code, which was shown to be the optimum block code for two transmit antennas and time domain coding. We show that the standard decoding algorithm results in significant performance degradation depending on the frequency-selective nature of the transmission channels, such that a low coherence bandwidth results in a huge degradation. The optimum decoding algorithm that alleviates this problem is the maximum-likelihood decoder for joint symbol detection. We present a performance analysis for the investigated space-frequency decoders in terms of the achievable BER results. Furthermore we compare space-time and spacefrequency coding and discuss the respective advantages and drawbacks of the different decoding algorithms in terms of their complexity. It should be noted that for the space-time approach we introduce the so-called matched-filter receiver, which shows significantly lower complexity compared to the maximum-likelihood decoder known from literature. The HIPERMAN system serves as an example OFDM system for quantitative comparisons.

Modeling and performance evaluations of Alamouti technique in a single frequency network for DVB-T2

“…DVB-T and DVB-T2 (Digital Video Broadcasting Terrestrial second generation) define an SFN corresponding to 0-dB Echo profile [4]. DVB-T2 incorporates the Alamoutispace-frequency [5][6][7][8][9] coded orthogonal frequency division multiplexing systems (COFDM) with a pair of transmitters [10] to eliminate these notches and has better performance. The Alamouti coding is a Multiple Input Single Output (two transmit antennas and a single receive antenna-2x1 MISO) system, in which every constellation point is transmitted by transmitters [5].…”

Experimental results on multicarrier MIMO HF communications

“…These restrictions severely limit the possible diversity strategies that may be implemented at transmission. Even for ground stations, space-time or spacefrequency diversity implementations using Alamouti codes [1,2] are extremely complex due to antennas coupling (transmission power can be several hundreds of Watts). Large separation between antennas avoids such a coupling, but introduces the critical issue of synchronization amongst transmitters.…”

Resource allocation and block coding within a three-stage collaborative broadband relay network

“…It can be seen that on the average, the third stage which is the weakest link is allocated more power in order to boost its performance, for instance with a 1 x 4, 4 x 4 and 4 x 1 configuration, the power allocated to each stage at 10dB is 1.3612, 0.2002 and 1.4386 respectively and likewise for 1 x 2, 2 x 2 and 2 x 1 is 1.5007, 0.2499 and 1.2494 respectively. In both cases the total power available to the network is constrained to K == 3 and the interstage allocation obeys equation (8).…”

“…In [8] an example of coding over a frequency selective channel is presented based on the Alamouti space time block code (A-STBC), which have the coding matrix…”