Super-orthogonal Space-time Trellis Codes Research Articles

Super-orthogonal differential space-time trellis coding and decoding

In this paper, a differential space-time trellis-coded scheme based on super-orthogonal space-time trellis codes (SOSTTCs) is proposed. It achieves full diversity and provides an improved coding gain. Based on the per-survivor processing (PSP) technique, a low-complexity suboptimal differential decoder is developed. In slow fading channels, it can approach the performance of SOSTTC with coherent decoding. Furthermore, in time-varying channels, a bank of recursive least square (RLS) type channel predictors are incorporated into the Viterbi decoder to track the channel variance and the RLS predictors do not need training data and channel statistics. The performance analysis is given. Simulation results are presented to illustrate our analytical results and they show that our scheme can achieve a good performance in both slow fading and time-varying fading channels with modest complexity.

Some super-orthogonal space-time trellis codes based on non-PSK MTCM

Super-orthogonal space-time trellis codes recently proposed in the literature are space-time trellis codes of full diversity and high rates systematically constructed by concatenating orthogonal space-time codes and multiple trellis coded modulation (MTCM). However, the existing MTCM only has designs for phase-shift keying (PSK) signals. In this paper, MTCM is extended from PSK signals to non-PSK signals in some special cases. With obtained constellations of MTCM, several super-orthogonal space-time trellis codes for two transmit antennas are presented. The 2- and 4-state codes have a simple mathematical expression for the coding gain distance (CGD), or diversity products. At rates 2.5, 3, 3.5, 4 bits/s/Hz, the newly proposed codes outperform the existing ones.

Space-time MSK Codes for Quasi-Static Fading Channels

In this paper, 4-state and 8-state space-time trellis codes with full rate, full diversity and high coding gain are proposed for MSK modulation, based on a technique similar to the super-orthogonal space-time trellis code (SOSTTC) design. Since the phase continuity requirement of MSK is the main constraint in space-time MSK code design not all the signal matrices corresponding to the trellis branches are orthogonal. The paper shows that the SOSTTC design technique can be extended to nonorthogonal coding structures. The new space-time MSK codes have frame error performances very close to those of their space-time QPSK counterparts given in [1]

Performance evaluation of super-orthogonal space-time trellis codes using a moment generating function-based approach

A new class of space-time codes called super-orthogonal trellis codes was introduced that combine set-partitioning with a super set of orthogonal space-time block codes in such a way as to provide full diversity with increased rate and improved coding gain over previous space-time trellis code (STTC) constructions. Here, we extend the moment generating function-based method, which was previously applied to analyzing the performance of space-time block orthogonal and trellis codes, to the above-mentioned super-orthogonal codes. It is shown that the maximum-likelihood metric and expressions for the pairwise error probability previously developed for the Alamouti (1998) space-time block code combined with multidimensional trellis-coded modulation can be readily extended to the super-orthogonal case. As such, the evaluation of the pairwise error probability for the latter can be performed in a similar manner to that previously described with the specific results depending on the particular trellis code design.

Super-orthogonal space-time trellis codes

We introduce a new class of space-time codes called super-orthogonal space-time trellis codes. These codes combine set partitioning and a super set of orthogonal space-time block codes in a systematic way to provide full diversity and improved coding gain over earlier space-time trellis code constructions. We also study the optimality of our set partitioning and provide coding gain analysis. Codes operating at different rates, up to the highest theoretically possible rate, for different number of states can be designed by using our optimal set partitioning. Super-orthogonal space-time trellis codes can provide a tradeoff between rate and coding gain. Simulation results show more than 2-dB improvements over the codes presented in the literature while providing a systematic design methodology.

Error Performance of Concatenated Superorthogonal Space-Time-Frequency Trellis Coded MIMO-OFDM System

In this paper, we investigate the performance of serially concatenated convolutional code with super-orthogonal space-time trellis code (SOSTTC) in orthogonal frequency division multiplexing (OFDM) over frequency selective fading channels. We consider both recursive systematic convolutional code (RSC) and non-recursive convolutional code (NRC) as the outer code, and 16-state QPSK SOSTTC as the inner code. Employing these, two concatenated schemes consisting of single convolutional outer code and two serially concatenated convolutional outer codes are proposed. We evaluate the performance of the concatenated schemes by means of computer simulations with maximum a posteriori (MAP) algorithm based iterative decoding. Simulation results indicate that the performance of the proposed concatenated schemes improved significantly when compared with schemes without concatenation under the same channel condition.