Zhang Bangning

The nonredundant error correction differential detection in soft-decision decoding

This paper proposes the application of nonredundant error correction (NEC) in soft-decision decoding. Combined with differential demodulation of /spl pi//4DQPSK, we emphasize the analysis of the new algorithm. A practical implementation scheme is presented. The BER performance and correction capability of NEC is investigated by computer simulation in AWGN and Rician fading channels. The simulation results show that the performance improvement of the proposed algorithm is superior to conventional differential demodulation by 1.4 dB at a BER of 10/sup -4/ in the AWGN channel. In the Rician channel there is the same notable performance improvement. The algorithm makes NEC able to be used in soft-decision decoding, which is widely applied in practical satellite communication systems. It overcomes the limitation that NEC could only be used in hard-decision systems. Therefore, the system capacity and communication quality is notably improved. It is worthwhile for satellite communication for which power and spectrum are limited.

Performance analysis of dual-hop satellite relay networks with hardware impairments and co-channel interference

In this paper, we investigate the impact of hardware impairments on the outage performance and the instantaneous capacity of dual-hop decode-and-forward (DF) satellite relay networks in the presence of co-channel interference. Specifically, the exact closed-form expression for the outage probability and the analytical expression for the instantaneous capacity of the system are derived over a shadowed-Rician fading channel, which provides a fast means to evaluate the impact of hardware impairments on the system performance. Our results demonstrate that the outage floor occurs and the capacity upper bound appears when the hardware impairments exist. In addition, simulation results were provided to verify the correctness of the analytical results.

A New Distance Property Analysis Algorithm for FTFs in DFH Systems

By considering the frequency transition as a coding process, a new state diagram based distance property analysis algorithm for frequency transition function (FTF) is derived in this paper. In this new algorithm the distance property can be quickly obtained by solving the state equations derived from the transition process of the state diagram. It is confirmed that the BER performances of DFH systems which are decided by the distance properties of FTFs can be easily and effectively acquired. The new algorithm provides an efficient distance property analysis tool for the construction of FTF, it can help to optimize the design of a DFH system. Numerical simulation results support the theoretical analysis result of our algorithm.

Performance of LDPC Coded SFH System with Partial-Band Interference

The application of Low Density Parity Check (LDPC) code in the anti-interference systems has drawn an increasing attention, due to its admiring performance which is very close to the theory limit. This paper focuses on a LDPC encoded slow frequency hopping (SFH) communication system with partial-band interference. Firstly, a modified soft-decision algorithm based on the utilization of interference information is proposed, and its performance is compared with some other soft-decision methods. Secondly, with numerical simulation, the influence of code rate, code length and the number of symbols per hops on the performance of the system with partial band noise interference is illustrated and examined in detail. Considering the great influence of hops per symbol on the performance, interleaver should be used and its influence on the performance is further examined by simulation. Finally, some constructive advices for the design of LDPC coded SFH system are given. Simulation results show that, with a reasonable design, the SFH system with LDPC code could achieve a desirable performance.

Research of P-code Direct Acquisition Technology

The article provides a new design of P-code direct acquisition module based on segmented coherent accumulation at frequency domain. Firstly, realizable solution of acquisition system is given, and its principle is introduced. Subsequently, according to specific environment where navigation terminal works, probability of detection and average acquisition time of acquisition system are deduced. The conclusion is proved by simulation, and average acquisition time and probability of detection are analyzed in different condition. Research shows that the P-code direct acquisition module works effectively at low signal-to-noise rate in high dynamic environment.

Performance improvement using beam diversity technique in GEO satellite communication system over correlated Nakagami-m fading channels

In GEO satellite communication with multi-beam antenna coverage, the decline of uplink performance will appear when the earth terminal near to the junction area of beams coverage. A method to solve the problem by beam diversity technique is studied in this paper. After presenting a new generation method of Nakagami-m fading channel simulation model, we build up a system model for the analysis of multi-beam diversity. In this model, terminal position, beam gain and channel fading level are taken into account. A number of results of simulation show that using beam diversity reception technique can effectively improve uplink performance of GEO satellite communication.

Performance of Impulse Radio and Direct-sequence Impulse Radio in the Presence of Interference

The performance of two ultra wideband communication systems is investigated. The two systems are time-hopping impulse radio (TH-IR) and a variation of it, termed direct-sequence IR (DS-IR). For both systems, binary pulse position modulation and binary pulse amplitude modulation are included respectively. Firstly, the difference between IR and direct sequence spread spectrum (DSSS) is studied. Next, a model for the system and interference is introduced. Particularly for the evaluation of the system performance, tone, multitone, partial-band and barrage interference signals are considered as the interference signals. A comparison between the interference suppression capabilities of TH-IR and DS-IR is carried out under conditions similar to both systems. It is shown that in most cases, the jam resistance of DS-IR is superior to that of TH-IR.

The applications of software radio in satellite communication

The applications of software radio in satellite communication are discussed and an idea of module design for a satellite communication system is proposed. The compiler functions of satellite communication are divided into several modules and each has its own functional software interface. The division and the design of modules and the operation of network management system are also discussed.