No abstract

Space‐time block code (STBC)–based multiple‐input–multiple‐output techniques have been considered recently to enhance the performance of mobile satellite communication systems in terms of link reliability. Uncoded space‐time labelling diversity (USTLD) is a diversity technique that is a direct extension of the STBC system and further improves its performance. A USTLD system is proposed in this paper that is designed specifically for satellite to mobile station links. The circular M‐ary Amplitude Phase‐Shift Keying (MAPSK) constellation, which is adopted by the most recent satellite broadcasting standard Digital Video Broadcasting standard for nonlinear satellite links (DVB‐S2X), is applied to the USTLD system. The most critical aspect of developing a USTLD system is the design of the secondary mapper to achieve labelling diversity. Existing square M‐ary Quadrature Amplitude Modulation (MQAM) approaches to USTLD mapper design are adapted for appropriate 16APSK and 64APSK constellations from the DVB‐S2X standard. Various metrics are derived to quantitatively compare mapper designs for a Nakagami‐q fading channel. Theoretical results, verified by Monte Carlo simulations, show that the best of the MAPSK USTLD mappers considered achieve a gain of approximately 4 dB for 16APSK and 5 dB for 64APSK when compared to the Alamouti STBC system. Furthermore, a study is conducted to analytically compare USTLD mappers using the derived metrics for both MQAM and MAPSK. It is concluded that a two‐stage approach is the most accurate methodology for comparing USTLD mapper designs.

Summary Greater spectral efficiency has recently been achieved for Uncoded Space Time Labelling Diversity (USTLD) systems by increasing the number of antennas in the transmit antenna array. However, due to constrained physical space in hardware, the use of more antennas can lead to degradation in error performance due to correlation. Thus, this paper studies the effects of spatial correlation on the error performance of USTLD systems. The union bound approach, along with the Kronecker correlation model, is used to derive an analytical expression for the average bit error probability (ABEP) in the presence of Nakagami‐q fading. This expression is validated by the results of Monte Carlo simulations, which shows a tight fit in the high signal‐to‐noise ratio (SNR) region. The degradation in error performance due to transmit and receive antenna correlation is investigated independently. Results indicate that transmit antenna correlation in the USTLD systems investigated (3 × 3 8PSK, 2 × 4 16PSK, 2 × 4 16QAM, and 2 × 4 64QAM) causes a greater degradation in error performance than receive antenna correlation. It is also shown that 2 × 4 USTLD systems are more susceptible to correlation than comparable space‐time block coded systems for 8PSK, 16PSK, 16QAM, and 64QAM.

SummaryUncoded space‐time labelling diversity (USTLD) is a recent scheme that improved the error performance compared to conventional multiple‐input, multiple‐output systems. Thus far, USTLD has suffered from limited achievable data rates, as the original model uses only two transmit antennas. This motivates for the work in this paper, where the USTLD model is extended to allow for any desired number of transmit antennas. An analytical bound for the average bit error probability of this high‐rate USTLD (HR‐USTLD) system is derived. This expression is verified using the results of Monte Carlo simulations, which show a tight fit in the high signal‐to‐noise ratio region. The increased data rates associated with larger transmit antenna arrays in HR‐USTLD systems come at the cost of increased detection complexity. Therefore, this paper studies the application of low‐complexity detection algorithms based on the popular QR decomposition technique and proposes a new algorithm specifically designed for HR‐USTLD systems. Analysis of this algorithm in terms of accuracy and computational complexity is also provided and benchmarked against maximum‐likelihood detection (MLD). It is shown that the proposed algorithm achieves near‐MLD accuracy, while reducing complexity by 79.75% and 92.53% for the respective 4 × 4 16QAM and 4 × 5 16PSK HR‐USTLD systems investigated.