Shushi Gu

Network-coded rateless coding scheme in erasure multiple-access relay enable communications

This study proposes a novel adaptive network-coded rateless coding scheme for an erasure multiple-access relay system with two distributed sources and an asymmetric network topology. To increase transmission efficiency, a two-dimensional degree distribution, as part of network-coded relay protocol, is designed based on the AND-OR tree analysis technique. The degree distributions of rateless coding at the sources and network coding at the relay are optimised by the linear programming approach under asymmetric channel conditions. Simulation results demonstrate that the proposed scheme outperforms existing classical relay protocols under time-varying channel conditions, and achieves a significantly better performance.

RCLTP: A rateless coding-based Licklider transmission protocol in space delay/disrupt tolerant network

Current space delay/disruption tolerant network architectures generally employ primary automatic retransmission request mechanism for reliable transport of application data. These architectures have obvious inefficiency over a long-haul, deep-space communication link because of frequent acknowledgments. In this paper, we propose a rateless coding-based space DTN transport protocol, named RCLTP, which integrates rateless erasure codes with ignorable retransmissions into the Licklider transmission protocol. As an underlying transport layer protocol in space DTN stack, RCLTP delivers data bundle redundantly to the next endpoint by stochastically interweaving the segments of it. Once the receiver of next-hop endpoint receives enough number of encoded segments, the bundle can be recovered accurately. Performance analyses and evaluations are given under the communication scenario from the Mars to the Earth. The evaluation results show that RCLTP shortens the file delivery time, improves the goodput performance and reduces the storage occupancy of DTN nodes.

A novel systematic raptor network coding scheme for Mars-to-Earth relay communications

In Mars-to-Earth communications, data transmission suffered severe losses due to the huge path-loss, extremely long propagation delay and lack of line-of-sight link in rovers-to-Earth. Based on delay/disruption tolerant networks (DTN), we proposed a systematic Raptor Network Coding (RNC) scheme for the multi-rovers transform data through an orbiter to Earth station communication scenarios. To enhance the reliability of rover-to-Earth file delivery, and considering the limited capacity of the relaying orbiter, a simplified network coding scheme is designed for the orbiter. We analyzed the asymptotic performance of RNC scheme. Moreover, an improved RNC (IRNC) scheme is optimized in a finite code-length and limited coding complexity. Simulation results show that, our RNC and IRNC schemes can achieve better performance in comparison with existing distributed rateless erasure codes.

Efficient Design of Polar Coded STTD Systems over Rician MIMO Channels

In this paper, a polar coded space-time transmit diversity (STTD) scheme is proposed in order to improve the performance of MIMO system. In Rician fading MIMO channels, the corresponding polar coded STTD system can be equivalent to a single transmission channel for each polar code bit. Density evolutions for the polar coded STTD systems are proposed based on the analyses of the single transmission channel. The proposed density evolutions provide preferable guidance to construct polar codes for the polar coded STTD systems. Simulation results show that the BER performance of polar coded STTD system is significantly improved as the number of antennas increases. The proposed \(2\times 2\) polar coded STTD system can provide better FER performance than LDPC-based system under low and mid code rates.

Design of Rateless Transmission Scheme Based on Punctured Polar Codes

In this paper, a parallel concatenated punctured polar (PCPP) codes is designed to realise the rateless property of polar codes. First, an improved random puncturing pattern of polar codes is proposed to archive better performance than random puncturing. Then, the optimal initial code rate is analyzed for multiple PCPP code blocks transmission in slow fading channels, which the optimal initial code rate of each new PCPP code block is determined by the overhead of the previous successful decoded code block and each packet can be transmitted with encoding construct of a 2-level PCPP codes.

Partially Observable Markov Decision Process-Based Transmission Policy over Ka-Band Channels for Space Information Networks

The Ka-band and higher Q/V band channels can provide an appealing capacity for the future deep-space communications and Space Information Networks (SIN), which are viewed as a primary solution to satisfy the increasing demands for high data rate services. However, Ka-band channel is much more sensitive to the weather conditions than the conventional communication channels. Moreover, due to the huge distance and long propagation delay in SINs, the transmitter can only obtain delayed Channel State Information (CSI) from feedback. In this paper, the noise temperature of time-varying rain attenuation at Ka-band channels is modeled to a two-state Gilbert–Elliot channel, to capture the channel capacity that randomly ranging from good to bad state. An optimal transmission scheme based on Partially Observable Markov Decision Processes (POMDP) is proposed, and the key thresholds for selecting the optimal transmission method in the SIN communications are derived. Simulation results show that our proposed scheme can effectively improve the throughput.

Double retransmission deferred negative acknowledgement in Consultative Committee for Space Data Systems File Delivery Protocol for space communications

To improve the reliability of file transfer and shorten file transfer time in space communication, this study aims to provide an improved strategy for deferred negative acknowledgement (NAK) in Consultative Committee for Space Data Systems File Delivery Protocol (CFDP). Based on a theoretical analysis of the recommended deferred NAK, the authors propose a double retransmission deferred NAK strategy instead to guarantee the reliability of file transfer; the file transfer time is reduced significantly using fewer retransmission spurts. They make the performance comparisons of the recommended deferred NAK in CFDP with the authors’ proposed strategy under several typical scenarios. Numerical and simulation results show the effectiveness of the proposed strategy.

Distributed rateless coded collaboration for satellite relay networks

In this paper, we propose a new distributed rateless coded collaboration, named DRCC, for packet transmission in an energy-limited satellite relay network. The rateless degree distributions on primary and secondary links are analyzed by AND-OR tree technique. Linear programming and multi-objective programming are both formulated to find the optimal solutions to minimize decoding error probability under various link conditions. At last, the simulation results demonstrate that our proposed DRCC scheme outperforms existing distributed rateless coding schemes with significantly better performances about packet error rate and system throughput for satellite networks.

Novel polar-coded space-time transmit diversity scheme over Rician fading MIMO channels

In this paper, a polar-coded space-time transmit diversity (STTD) scheme is proposed in order to improve the performance of multiple-input multiple-output (MIMO) system. In Rician fading MIMO channels, the corresponding polar-coded STTD system can be equivalent to a single transmission channel for each polar code bit. Density evolutions for the polar-coded STTD systems are proposed based on the analyses of the single transmission channel. The proposed density evolutions provide preferable guidance to construct polar codes for the polar-coded STTD systems. Simulation results show that the BER performance of polar-coded STTD system is significantly improved as the number of antennas increases and the influence of the variable Rician K-factor of MIMO channels gradually vanishes. The proposed 2 × 2 polar-coded STTD system can provide better frame error rate (FER) performance than low-density parity-check (LDPC)-based system under low and mid code rates, and the average advantage is 0.3 dB approximately when the code rate is 0.25 and 0.2 dB when the code rate is 0.5.

Rate-Compatible Transmission Schemes Based on Parallel Concatenated Punctured Polar Codes

In this paper, an improved random puncturing pattern of polar codes is proposed, where only the frozen bits can be selected to puncture. Compared to the existing random puncturing schemes, our improved random puncturing scheme can achieve 0.2-1dB decoding performance improvement. Then, an optimized rate-compatible hybrid automatic repeat request (HARQ) transmission scheme is proposed based on parallel concatenated punctured (PCP) polar codes. By analyzing the overhead of the previous successful decoded coding block in our rate-compatible HARQ scheme, two methods of determining the optimal initial code-rate of each new PCP polar coding block are proposed over a time-varying channel. Simulation results show that the average number of retransmissions is about 1.5 times in our proposed rate-compatible HARQ schemes with a 2-level PCP polar encoding construct, which reduces half of the average number of retransmissions than the existing rate-compatible polar coding scheme.