Abstract
Adaptive coded and modulation (ACM) is an effective measure to resist rain attenuation in Ka-band satellite communications. The accuracy of the estimator for signal-to-noise ratio (SNR) is one of the main factors that affect ACM performance. This paper establishes the channel model of satellite communication in Ka-band and derives and analyzes data-aided (DA) maximum likelihood (ML) and method-of-moments estimators for SNR of continuous phase modulation (CPM) in Ka-band fading channel. Simulations and analysis indicate that the normalized mean square error (NMSE) of the DA ML estimator is closer to the Cramer-Rao bounds (CRB) at low SNR, but the performance worsens with the SNR increases from medium to high values. The M2M4 estimator performs poorly at low SNR and best at medium SNR. When the SNR is low, the performance of the DA ML estimator is better than the M2M4 estimator; however, the two estimators have similar performance when SNR is high. The performances of the two estimators will become increasingly better the greater the lengths of the observation signals become. However, the influence of the signal length will become increasingly smaller as the SNR becomes larger.
Highlights
Many bands can be used for satellite communication; these bands include L, S, C, Ku, and Ka bands
For the continuous phase modulation (CPM) modulator, the modulation index is set to h = 1/4, the pulse shaping function is set to Gaussian minimum shift keying (GMSK), L = 2, and the modulation order is set to M = 8
When the signal-to-noise ratio (SNR) is less than 10.6 dB, all the three modulation orders can’t achieve the target BER, we13 of 15 can choose a low BER method as the modulation order of the system, that is M = 8
Summary
Many bands can be used for satellite communication; these bands include L, S, C, Ku, and Ka bands. While with the exploitation of extremely high-frequency (EHF) bands (30–300 GHz) for broadband transmission over satellite links, the Q-V band (30–50 GHz) and W-band (75–110 GHz) seem to offer very promising perspectives [2]. This paper use Ka-band as the operating frequency band for satellite communication because of the advantages of the wideband, little disturbance, and small-sized terminals [3]. At frequencies beyond 10 GHz, rainfall is one of the important atmospheric parameters (hydrometeors) which causes signal degradation along both terrestrial and satellite tracks [4,5,6]
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