Super-orthogonal space-time-frequency trellis coded OFDM

Super-orthogonal space-time trellis codes (SOSTTCs) given in the literature are full rate and provide full spatial diversity with high coding gain in narrowband quasistatic fading channels. The high number of parallel transitions in their trellis structure restricts their performance in wideband channels where the code performance suffers from multipath. Code design criteria are derived and a computer search based method is proposed to design full-rate optimised SOSTTCs exploiting full spatial and multipath diversity for multiple-input multiple-output orthogonal frequency division multiplexing systems. The proposed codes have codewords defined in space, time, and frequency. We evaluate the codeword error rates of the new 16, 32 and 64-state super-orthogonal space-time-frequency trellis codes for quadrature phase shift keying by computer simulation and show that they provide significant error performance improvement compared to their counterparts with equivalent delay length     

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.     

Performance and jitter analysis of quadrature partialresponse/trellis coded modulation (QPR-TCM) signals in the presence ofintersymbol interference and colored noise

To improve both bandwidth efficiency and error performance, partial response signaling and trellis coded modulation are considered together for QAM. A new receiver for a data transmission system employing combined partial response/trellis coded modulation (QPR-TCM) is investigated. Combined 6QPR-TCM and 42QPR-TCM systems are introduced. Simulation studies in the ISI environment are done. In a colored noise environment, the error probability of 6QPR-TCM is analytically lower bounded and compared to the classical 4QAM-TCM. An optimal (QPR-TCM) scheme is proposed which improves both jitter and error response in a colored noise environment     

Full-rate full-diversity STBCs for three and four transmit antennas

A novel technique is presented for the construction of full-rate, fulldiversity space?time block codes (STBCs) from orthogonal STBCs (OSTBCs), having empty slots left in their codeword matrices for orthogonality. Two new STBCs are obtained, which are both fullrate and full-diversity, for three and four transmit antennas. The higher decoding complexity of these structures is reduced owing to non-orthogonality by using a conditional maximum-likelihood decoder. The new optimised codes provide better error performance than their full-rate full-diversity counterparts given in the literature.     

Multilevel coded CPFSK systems for AWGN and fading channels

In this paper, we introduce multilevel coded continuous-phase frequency-shift keying (CPFSK) systems for both additive white Gaussian noise and fading channels based on multilevel coding and multistage decoding techniques. These schemes are designed under the constraint M⩾2P for M-ary CPFSK with modulation index J/P. In order to maintain the phase continuity property after multilevel coding, we use some specific set partitioning rules. We construct examples to show that the proposed systems outperform the corresponding conventional one-level schemes. For the fading case, we consider an ideal fading channel where adjacent fading symbols are assumed to be independent and a correlated fading channel where bit interleavers are needed at each coding level. The computer simulation results show that the proposed systems have bit-error performance and decoder complexity advantages over the corresponding reference codes taken from the literature. It is also shown that there is only a slight degradation on the bit-error performance for correlated fading, compared to the ideal fading case     

Bandwidth-efficient code design for coordinate interleaved coded cooperation

A two-user coordinate interleaved coded cooperation scheme is proposed for quasi-static Rayleigh fading channels, where cooperative and modulation diversity techniques are properly combined to take their full advantage. Two selective cooperation schemes are considered related to whether users know the cooperation case or not. Pairwise error probability (PEP) analysis is performed for all cooperation cases and code design criteria are derived from the PEP upper bounds. Bandwidth-efficient 4-, 8- and 16-state rate 2/4 cooperative quadrature phase shift keying (QPSK) trellis codes are obtained based on these criteria by means of exhaustive computer search. The error performances of the new codes evaluated by computer simulations show their superiority compared to the corresponding best space-time codes used in cooperation with coordinate interleaving. The simulation results are supported by an upper bound on the bit error probability developed using union bounding technique.     

New ternary line codes based on trellis structure

The trellis coding technique is applied to line-coded baseband digital transmission systems. For R=n/n+1(n=1,2,3) coding rates, a new codeword assignment model is proposed to accomplish basic requirements for line coding in which each length n binary data sequence is encoded into a length n+1 ternary (+,0,-) line codeword chosen among the code alphabet with 2ⁿ⁺² elements. Assuming Viterbi decoding, the system error performance is improved by increasing the free Euclidean distance between coded sequences. A new algorithm is given for the calculation of the free distance between line-coded sequences so obtained. For R=1/2 and R=3/4 rates, the analytical error performance upper bounds are derived. The power spectral densities of the new line codes are also calculated and compared with those of known line codes