Xiangming Li

Combined Fountain Code with Network Coding in Cooperative Communication

In this paper, we will investigate the block error rate (BLER) performance in cooperative communication, through combining fountain code with network coding. Contrast to the fixed-rate code, the rate of fountain code is not determined in advance, since that varies according to the instant channel state information. Under the error-free channel condition, network coding can get the maximum possible rate through coding at the correlative nodes not just store-and-forward. Based on this, the error-tolerant coding scheme is proposed by means of integrating fountain code with network coding in cooperative communication. Simulation results show that the proposed scheme can obtain the lower block error rate (BLER), compared with detect and forward scheme.

Rateless codes aided coherent M-ary PSK systems in the presence of receiver imperfections and Rician fading

In this paper, we study the bit error rate (BER) and the symbol error probability (SEP) performance for a rateless coded M-ary phase-shift keying (MPSK) system in a situation where stochastic phase error, quadrature error and in-phase–quadrature (I–Q) gain mismatch take place all concurrently over a Rician fading channel. Similar scenario has been considered before by Djordjevic et al. for quasi-cyclic low-density parity-check (QC-LDPC) codes, but the effect of I–Q gain mismatch is not correctly modeled, because the Gaussian noise components in I and Q paths are assumed to have the same variance. By taking two different Gaussian noise variances into consideration, precise expressions are derived for the SEP of a coherent MPSK system under the aforementioned condition (with the stochastic phase error depicted by Tikhonov distribution), thus providing a baseline to evaluate the merits of the proposed rateless coded system and that of QC-LDPC codes. The validity of the rateless coded system is substantiated by simulation results. It is observed that rateless codes outperform QC-LDPC codes even the I–Q gain mismatch is modeled in the same way as Djordjevics work when the target BER is lower than 10−2. Copyright

An Effective Protocol for Rateless Coding aided Cooperative Communications

In this paper, we study the bit error rate (BER) and the frame error rate (FER) performance for rateless coding aided cooperative communications using an effective protocol over additive white Gaussian noise (AWGN) channels. During the collaborative phase , t he proposed protocol adopts an adaptive demodulation (ADM) scheme considered channel state and the partial cooperation scheme depending on whether or not the partner decodes correctly. ADM schemes have been considered before by Illanko et al. , but therein the effect of channel state is not considered, because the receiver always demodulates three (or two) bits per symbol for the case of 16QAM signaling during two phases in cooperative communications. Taking channel state into consideration, the BER performance of the modified ADM scheme is investigated. The proposed cooperative protocol is studied with different partial cooperation parameters, such as 1/2, 1/4, and 1/8 . Furthermore, the validity of the partial cooperative scheme over flat Rayleigh fading channels is also substantiated by simulation results in terms of throughput and FER performance.

Fountain codes based partial cooperation in cooperative communications

To improve the throughput performance without feedback channel, a partial cooperation scheme based on fountain codes is proposed in this paper. Compared with the incremental relaying where the signal is retransmitted in fixed or selective relay and fed back to the source from the destination, the proposed scheme only requires the partner to offer partial encoded packets in collaborative phase. Simulation results show that throughput performance of the proposed scheme outperforms that of incremental relaying, which has ever been considered as the optimal scheme in three-terminal cooperative communications system with the partial cooperation parameter around 0.1 in our simulation. In particular, the proposed scheme allows for an easy extension to multiple partners.

Performance Evaluation of Relay-Aided Multi-cell OFDMA System

In this paper, we consider the throughput performance in relay-aided multi-cell orthogonal frequency division multiple access (OFDMA) system, when mobile user (MS) is uniformly distributed and relay station (RS) is located at some typical positions, such as dRS = 0:5 and dRS = 0:85, where dRS is the ratio between the distance from RS to base station (BS) and the cell radius. Although cooperative diversity and frequency reuse improve the throughput gain, more spectral and time resources will be occupied. Simulation results demonstrate that multi-cell system with RS deployed obtains very limited throughput gain compared with non-relay system. Whereas, if free space optics (FSO) or wired link is available between BS and RS, the throughput performance will be improved significantly.