Kenan Aksoy

Super-orthogonal space-time-frequency trellis coded OFDM

In this paper, we present a new space-time-frequency coded orthogonal frequency-division multiplexing (OFDM) scheme that achieves high diversity gain through frequency-selective multipath fading channels with L taps. The proposed serial concatenated scheme combines an inner super-orthogonal space-time-frequency trellis code (SOSTFTC) with an outer punctured convolutional code (PCC) that provides additional coding and diversity gain, so that the overall diversity of the system becomes Gd = Nr ×min{Lgdfree,NtL} where Nt and Nr are the number of transmit and receive antennas, respectively, Lg is the build-in space-frequency diversity of the SOSTFTC, and dfree is the outer code?s minimum Hamming distance. The bit error rate (BER) for an example concatenated code employing inner 16-state QPSK SOSTFTC was evaluated by computer simulations and it is shown that significant error performance improvement is obtained.

An Efficient Concatenated TCM and Coordinate Interleaved STBC for Wideband Channels

In this paper, we propose an efficient concatenated trellis coded modulation (TCM) and coordinate interleaved space- time block coded (STBC) orthogonal frequency division multiplexing (OFDM) system providing full spatial and multipath diversity with considerable diversity increase compared to the techniques given in the literature. The pairwise error probability (PEP) analysis of the proposed system for two transmit antennas shows that the achievable diversity is doubled and a signal to noise ratio (SNR) gain of approximately 3 dB is provided for the same codeword error rate (CER) compared to the concatenated TCM and STBC OFDM system given in Y Gong & K B Letaief (2003) with modest increase in coding and decoding complexities.

Concatenated Trellis and Coordinate Interleaved Differential Space-Time Block Codes for OFDM

We propose a concatenated trellis code (TC) and coordinate interleaved differential space-time block code (STBC) for OFDM. The coordinate interleaver, provides signal space diversity and improves the codeword error rate (CER) performance of the system in wideband channels. Coordinate interleaved differential space-time block codes are proposed for the concatenated scheme. TC design criteria are derived, and the CER performances of the proposed system are compared with existing concatenated TC and differential STBC. The proposed scheme has superior diversity gain and improved CER performance compared to the existing differential schemes.

An efficient differential MIMO-OFDM scheme with coordinate interleaving

We propose a concatenated trellis code (TC) and coordinate interleaved differential space-time block code (STBC) for OFDM. The coordinate interleaver, provides signal space diversity and improves the codeword error rate (CER) performance of the system in wideband channels. Coordinate interleaved differential space-time block codes are proposed and used in the concatenated scheme, TC design criteria are derived, and the CER performances of the proposed system are compared with existing concatenated TC and differential STBC. The comparison showed that the proposed scheme has superior diversity gain and improved CER performance.

System Optimization for Serial Concatenated OFDM with Extended Constellation STBC

We propose a serial concatenated convolutional and extended constellation space-time block coded (SC-EC-STBC) OFDM scheme that achieves high diversity gain through frequency-selective multipath fading channels. The new scheme combines an inner accumulated linear constellation coded space-time block code (LCC-STBC) with an outer convolutional code (CC) that provides additional coding and diversity gain. The iterative decoder performance of proposed system is optimized via extrinsic information transfer (EXIT) diagrams, and the bit error rate (BER) performance improvement provided by the proposed system with iterative decoding is confirmed by computer simulations.

Comments on "Combined turbo codes and interleaver design"

The authors comment that in the paper of Yuan, Vucetic and Feng (see ibid., vol.47, p.484-87, Apr. 1999), the optimum distance spectrum (ODS) code found for memory order v=5, is actually v=3 convolutional code. The ODS code with h/sub 0/=43/sub s/ and h /sub 1/=55/sub s/ is actually v=3 code, because the feedback polynomial h/sub 0/, and feedforward polynomial h/sub 1/ are not relatively prime polynomials.