M-ary Phase Shift Keying Amplitude Research Articles

Optimal rotation angle for finite constellation over additive white Gaussian noise multiple access wiretap channel

The achievable secrecy rate regions of various multi-user channels with Gaussian inputs are well-known in the literature. To gain more practical insights into the achievable rates, it is more useful to consider channels with inputs from finite constellations, such as M-ary quadrature amplitude modulation (M-QAM), M-ary phaseshift keying (MPSK), M-ary amplitude phase-shift keying (M-APSK) etc. The authors study the achievable secrecy rates with a constrained constellation input for a multiple access wiretap channel with an eavesdropper. They also show that if the constellation points are rotated relatively for the two users then the secrecy sum-rate can be improved. They perform Monte–Carlo simulations for computing these secrecy rates for classical modulation schemes including BPSK, quadrature phase-shift keying, M-QAM, M-PSK, M-PAM, and M-APSK. They also derived an approximate function, whose argument of supremum provides an approximately optimal rotation angle for obtaining a maximum secrecy sum-rate. they also show, via simulations, that rotation of constellation is helpful for some range of signal-to-noise ratio only, which is contrary to the results of multiple access channel without security constraint. Finally, they consider a more realistic scenario, where the channel from transmitters to receivers and eavesdroppers is time-varying. They consider the case of complex circularly symmetric Gaussian random channel gains and compute the optimal rotation angle, which will maximise the expected value of an upper bound of the secrecy sum-rate.

Four-Dimensional Signal Constellations Based on Binary Frequency-Shift Keying and <i>M</i>-ary Amplitude-Phase-Shift Keying

In this article, we give the construction of new four-dimensional signal constellations in the Euclidean space, which represent a certain combination of binary frequency-shift keying (BFSK) and M-ary amplitude-phase-shift keying (MAPSK). Description of such signals and the formulas for calculating the minimum squared Euclidean distance are presented. We have developed an analytic building method for even and odd values of M. Hence, no computer search and no heuristic methods are required. The new optimized BFSK-MAPSK (M = 5,6,···,16) signal constructions are built for the values of modulation indexes h =0.1,0.15,···,0.5 and their parameters are given. The results of computer simulations are also provided. Based on the obtained results we can conclude, that BFSK-MAPSK systems outperform similar four-dimensional systems both in terms of minimum squared Euclidean distance and simulated symbol error rate.

USTLD mapper design for APSK constellations over satellite links

AbstractSpace‐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.

A new performance metric for M-APSK receivers

Synchronization is a critical function that determines the overall performance and complexity of the receiver of any communications system. The implementation and evaluation of effective synchronization algorithms still comprises a challenging task that requires accurate testing methods, which are based on measurements collected at various processing stages. M-ary Amplitude-Phase Shift Keying (M-APSK) constellations are used in modern communications systems, such as digital video broadcasting and interactive broadband satellite services, due to their bandwidth efficiency characteristics. This paper presents a new metric that can be associated with the signal quality at various synchronization mechanisms used in M-APSK receivers. Apart from the metric's mathematical derivation, the paper presents various experimental results based on single (QPSK, 8PSK), two (16APSK) and three (32APSK) ring M-APSK schemes employed in DVB-S2 systems.

POWER AND BANDWIDTH-EFFICIENT CIRCULAR M-ARY APSK SCHEMES WITH LOW PAPR

This paper presents a class of circular M-ary Amplitude-Phase Shift Keying (APSK) signaling techniques with high bandwidth efficiency and low peak-to-average power ratio (PAPR) suitable for systems using nonlinear power amplifiers to achieve high power efficiency. For nonlinear amplification, good performance requires not only high squared minimum distance to average power ratio (DPR) but also low PAPR. A search algorithm for M-ary APSK schemes using circular constellations suitable for nonlinear amplification with minimum PAPR and maximum DPR is developed. Results for 8-, 16-, 32-, 64- and 128-APSK signalling schemes are presented. The effects of bandlimiting filter sharpness on the PAPR are examined and considered in the development. The analytical and simulation results show that this class of circular M-ary APSK signals outperforms the square and cross M-ary QAM schemes.