Dongping Yao

An improved high-speed RS encoding algorithm

Taking RS encoder in CMMB system for example, we proposed an improved algorithm according to the method of bit-parallel multiplier based on dual basis. The new algorithm can achieve a higher rate, and the RS encoder can be applied in a wide range of systems when implemented in FPGA.

Measurements and Modeling of Cross-Correlation Property of Shadow Fading in High-Speed Railways

With the fast development of high-speed railways, the need for wireless communication to satisfy secure demand of train and application demand of passengers has become evident.As a part of large- scale propagation effects, shadow fading is of great importance to design hand-over algorithm, and to evaluate macro diversity gain in wireless communications. This paper offers an investigation on the cross-correlation property of shadow fading in high-speed railway (HSR) network, based on the empirical data measured along Xingyang to Luoyang HSR line of China. The measurements indicate that the crosscorrelation coefficient of shadow fading is correlated to the separation distance between two base stations. Several models, to describe the relation between the cross-correlation coefficient and the separation distance, are proposed and compared with each other in this paper, and a decaying exponential model is finally suggested to characterize the cross-correlation property in the HSR environments.

Implementation of LTE-R transceiver and the performance with WINNER D2a channel model

With the rapid development of high-speed railway, the train speed can reach up to 350 km/h. Much more technical demands for high-speed railway mobile communication system are put forward. As the next generation wireless communication technology of 3GPP, Long Term Evolution for railway, known as LTE-R, is proposed to provide railway communication services including railway control, passenger services, wireless surveillance video, etc. The main goal of this paper is to evaluate the detailed performance of LTE-R on the WINNER D2a channel model which has been presented as an appropriate choice for the wireless channel model in high-speed scenario, and implement a LTE-R transceiver based on LabVIEW software and National Instruments Universal Software Radio Peripheral 2920 (NI USRP2920) platform for further research. The experimental results show that LTE-R has promising potential to be used in high-speed railway scenario.

A modified PEG algorithm for construction of LDPC codes with Polynomial of Cycle

Progressive Edge-Growth (PEG) algorithm is a novel approach for construction of low-density parity-check (LDPC) codes with large girth. However, PEG algorithm ignores the effect of the number of shortest cycles. In this paper, we propose a modified PEG algorithm with Polynomial of Cycle, which achieves not only large girth, but also minimizes the number of shortest cycles significantly. Simulation results show that our proposed algorithm can improves the performance of LDPC codes.

A precise approach for computing channel soft information

LDPC (Low-Density Parity-Check) codes have a good performance close to the Shannon limit. To make full error-correcting performance, soft information is used in iterative decoding algorithm. For different types of modulation, there are different expressions of channel soft information. In this paper, we propose approaches for computing channel soft information precisely for BPSK, QPSK, 16QAM, instead of approximation. Taking the example of CMMB standard, simulation of channel coding with channel soft information is done.

A double differential space-frequency MIMO precoding scheme of LTE in high-speed railway environment

The next-generation LTE standards operating on high-speed trains faces the problems about fast time-selective and frequency-selective channel. Precoding relying on accurate channel information at the transmitter or receive feedback will be less effective in such scenarios. Based on WINNER D2a channel model for high-speed railway, double differential space- frequency precoding scheme is proposed. Double differential space-frequency block coding is introduced into frequency domain in an OFDM system. It does not require any channel state information, with low complexity and antenna diversity gains at the transceiver. More importantly, the scheme should be robust to handle doppler shift Its shown that the proposed scheme keeps good performance in the WINNER D2a channel for high-speed railway.

Multicarrier modulation techniques for TETRA II

TETRA is a digital trunked communication system. TETRA II adopt Filtered Multitone Modulation (FMT) multicarrier scheme to provide high speed data service. This paper introduce modulation parameters which are defined in TETRA II standard and efficient implement, then simulate and analyze the BER performance in AWGN and multipath channel.

The implementation of TETRA using GNU Radio and USRP

TETRA (Terrestrial Trunked Radio) is a digital trunking communication standard which is recommended by ETSI (European Telecommunications Standards Institute) and has been widely used in the world. It has been used in many areas such as underground, fire protection, police system. SDR (Software Defined Radio) is a technology which just changes the software without changing the hardware to implement different communication systems. The combination of GNU Radio and USRP is such a high speed, cost effective SDR platform. GNU Radio is an open source software project which can support SDR. And USRP (Universal Software Radio Peripheral) is the hardware which is the most important hardware partner of GNU Radio. This paper focuses on using GNU Radio and USRP to implement the pi/4 DQPSK modulation and demodulation technology, the main modulation method in TETRA I. Besides, transmit and receive the modulated signal in the real wireless channel.

Path loss characteristics for vehicle-to-infrastructure channel in urban and suburban scenarios at 5.9 GHz

This paper investigates path loss characteristics for Vehicle-to-Infrastructure (V2I) communications in urban and suburban scenarios. We carried out measurements at 5.9 GHz. The transmitter antenna heights are 3.5 m and 1.5 m and the position of the receiver antenna is on the roof of the car. Then we analyzed the path loss characteristics by using the measured data. The results are helpful for the V2I communications system design.

Development of LTE-based channel tester for high-speed scenario

This paper focuses on a channel testing scheme based on public LTE network for high-speed scenario. To simplify the deployment of channel testing for high-speed scenario, public LTE CRS in downlink can be utilized so that setting up a transmitter is avoided. A receiver system was designed and the testing was carried out on a high-speed train. Before the field testing a verification for receiver via radio communication tester and channel simulator was done. The result are helpful for the receiver design.