A Tone-Aided/Dual Vestigial Sideband (TA/DVSB) system for mobile satellite channels

Tone-aided modulation is one way of combatting the effects of multipath fading and Doppler frequency shifts. A new tone-aided modulation format for M-ary phase-shift keyed signals (MPSK) is discussed. A spectral null for the placement of the tone is created in the center of the MPSK signal by translating the upper sideband upwards in frequency by the same amount. The key element of the system is the algorithm for recombining the data sidebands in the receiver, a function that is performed by a specialized phase-locked loop (PLL). The system structure is discussed and simulation results showing the PLL acquisition performance are presented

Carrier recovery techniques on satellite mobile channels

An analytical method and a stored channel model were used to evaluate error performance of uncoded quadrature phase shift keying (QPSK) and M-ary phase shift keying (MPSK) trellis coded modulation (TCM) over shadowed satellite mobile channels in the presence of phase jitter for various carrier recovery techniques

A diversity combining antenna array for land mobile satellite communications

A unified approach to adaptive antenna array design and transceiver signal processing architectures is proposed for the user segment of the land mobile satellite communication service. This technique is described in its conceptual form, and compared with steered antenna array configurations currently favored for this class communication system. The proposed system uses established diversity combining techniques previously developed for mobile terrestrial radio. It is suggested that a diversity-based receiver architecture would allow the coherent recombination of the multipath signal energy present at the mobile terminal site, and thereby enhance system performance for a given link budget. The cophasing of the multipath signals can be implemented using a FFSR (feedforward signal regeneration) signal-processing architecture, which uses the presence of a pilot-tone within the communications channel. On transmit, a retrodirective beam is formed towards the active satellite. The economic viability of such a transceiver is also considered

An Analysis of Pilot Symbol Assisted Modulation for Rayleigh Fading Channels

Abstract-Proposals have appeared recently for the use of pilot symbols to mitigate the effects of rapid fading in mobile communications. Unlike the more familiar pilot tone systems, pilot symbol assisted modulation (PSAM) does not affect the transmitted pulse shape or the peak-to-average power ratio, and implementation is straightforward. This paper puts PSAM on a solid analytical basis, a feature missing from previous work. It presents closed form expressions for the BER in BPSK and QPSK, for a tight upper bound on SER in 16QAM, and for the optimized receiver coefficients. The error rates obtained are lower than for differential detection for any combination of SNR and Doppler spread, and the performance is within 1 dB of a perfect reference system under slow fading conditions, and within 3 dB when the Doppler spread is 5% of the symbol rate