Yafeng Zhan

Design of Efficient Joint eIRA-Coded MSK Modulation Systems for Space Communications

An efficient scheme of extended irregular repeat-accumulate (eIRA-) coded minimum shift keying (MSK) is presented. Based on an extrinsic information transfer (EXIT) chart, it is designed as an eIRA code, incorporating a continuous-phase encoder (CPE) decomposed from MSK. Our scheme and a contrasting scheme of another eIRA-coded MSK are simulated in an additive white Gaussian noise (AWGN) channel. Simulation results show that our scheme outperforms the contrasting scheme by about 2 dB at a bit error rate (BER) of and has the same performance of an optimal eIRA-coded binary phase shift keying (BPSK). In addition, our scheme obtains lower complexity and less decoding latency because all differential encoders in the eIRA code are eliminated, while adding some differential decoders. Thus, the two-level Tanner graph-based decoding in the contrasting scheme is reduced. Therefore, the proposed scheme can be efficiently applied to satellite and deep space communications.

Concatenated eIRA Codes for Tamed Frequency Modulation

A new scheme of the extended irregular repeat- accumulate (eIRA) coded tamed frequency modulation (TFM) for deep space communications is introduced in this paper. It is mainly based on the optimal concatenation of the eIRA code and the continuous phase encoder (CPE) decomposed from TFM. In order to obtain good performance of the eIRA coded TFM, the main principle of our scheme is to jointly optimize the concatenation by eliminating the short loops in the Tanner graph of the eIRA code and the coding part of TFM and to jointly decode between them. Then our scheme without interleaving and the contrast scheme with interleaving are simulated in an additive white Gaussian noise (AWGN) channel which is typical in deep space communications. Simulation results have shown that our scheme can obtain lower complexity and less decoding delay (due to the reduction of interleaving) at the cost of just 0.1-0.15 dB performance loss when compared to the scheme with interleaving given bit-error-ratio (BER) of 10 5. Therefore, our scheme can be used to implement the coded TFM system for deep space communications with good performance and low complexity.

A Receiver Structure of Joint LDPC Decoding and Synchronization for Deep Space Communications

A receiver structure based on a joint LDPC decoding and synchronization algorithm and realized on an FPGA platform is introduced. The realization system achieves the BER of 1e-5 at the channel SNR of -4.6 dB with moderate hardware complexity, and the performance degradation is less than 1.3 dB from the ideal situation. So it is suitable for deep space communications and other wireless communications.

Solar system interplanetary communication networks: architectures, technologies and developments

With the development of deep space exploration technologies, main space agencies all over the world are working hard to develop the solar system interplanetary communication networks (SSICN). SSICN is a perspective communication networking system characterized by high data rate, high intelligent and perfect interconnection, which could provide the deep-space mission control and scientific application with the convenient, reliable and secure data transmission services. Following the introduction of future deep space exploration prospect, this paper analyzes the similarities and differences for three networks, terrestrial internet, near Earth space networks and SSICN, then discusses the key technologies and research trends of SSICN in details, and finally proposes the suggestions for the construction of future Chinese SSICN.

Review of channel models for deep space communications

This paper presents a comprehensive review of channel models for deep space communications. Based on the characteristics of environment, deep space channels can be divided into three kinds, i.e., near Earth link, interstellar link and near planet link. The modeling for different kinds of channels are summarized respectively, and some simulation results are provided in this paper. In addition, according to the development trend of deep space communications, optical wave will become an important carrier in the future. Therefore, deep space optical communication is also briefly introduced. Finally, challenges of deep space channel modeling are pointed out and future research direction is also discussed.

A General Carrier Lock Detection Algorithm for MPSK Signal

A general metric function of carrier lock detection, based on Mth-power for MPSK signal is proposed. The expectation of this metric functions output is independent of noise, only related to the signal power. It is easy to judge the carrier loop whether in a lock state or not, with low complexity cost. By median filtering the output of metric function, the reliability of carrier lock detection could be improved. Theoretical analysis and computer simulations show that the proposed method is universal and effective for MPSK systems.

4-Transmit-Antenna STBC with 1 Bit Differential Feedback over Time-Selective Fading Channels

In this paper, a 4-transmit-antenna space time block coding (STBC) scheme with 1-bit differential feedback is proposed. This scheme gives full transmit diversity and spatial coding rate over time-selective fading channels by rotating the signal constellations for certain angles determined by the differential feedback information. By utilizing differential feedback, our method can provide much better channel orthogonality and track the variation of the channel more accurately and timely under time-selective fading circumstances, comparing to recent works presenting other quantized feedback schemes. Simulation results show that the 1-bit differential feedback scheme achieves near-optimum performance and outperforms existing algorithms without adding more overhead or complexity.

MMSE-Based Block Implementation of Constant Modulus Algorithm

This paper introduces a new parallel scheme of Godards constant modulus algorithm which can be easily implemented by hardware. With the criterion of Godards constant modulus, stochastic gradient decency and block minimum mean square error, it realizes a parallel equalizer by adaptively adjusting the tap-weight vector. From numeric analysis and simulation, it is manifested that our scheme for quadrature phase-shift keying (QPSK) communication systems can achieve fast parallel equalization at the cost of less than 3 dB BER performance loss than the theoretic BER performance under low Eb/No (Eb/No is less than 10 dB) when the channel condition is rather severe. Therefore, it can be used to overcome the speed limitation of hardware for designing and implementing parallel blind equalizers especially in digital modems with high data rate.