Diversity order of decode-and-forward MIMO relaying with transmit antenna selection

This article analyzes the diversity order of several proposed schemes, where the transmit antenna selection （TAS） strategies are combined with low-complexity decode-and-forward （DF） protocols in the multiple-input multiple-output （MIMO） relaying scenario. Although antenna selection is a suboptimal form of beamforming, it enjoys the advantages of tractable optimization and low feedback overhead. Specifically, this article proposes schemes that combine TAS strategies with fixed decode-and-forward （FDF） and selection decode-and-forward （SDF） protocols. Following that, the asymptotic expressions of outage probabilities are derived and the diversity order of the proposed schemes analyzed. These kinds of combination of transmit antenna selection strategies and low-complexity decode-and-forward protocols can achieve partial diversity order in the MIMO relaying scenario. The numerical simulations verify the analysis.

Time-Domain Dual Component Computation Diversity Based on Generalized Hybrid Carrier

In this paper,the concept of computation diversity is proposed by employing generalized hybrid carrier(GHC)system.The signal is backed up by transform-domain computation to enhance the anti-fading capability.Theoretical analysis is presented to demonstrate the superiority of the proposed method.Numerical simulations in doubly-selective fading channels are provided to verify the results.The bit error rate(BER)performance is guaranteed with a small computational complexity increment.The proposed method not only extends the new diversity dimension,but also improves the diversity gain of the system without occupying additional wireless resources.Moreover,the proposed method shows good adaptability with single carrier modulation and improves diversity performance.As the simulation results shown,time-domain dual component computation diversity(TDC-CD)has 1d B BER gain and 0.1diversity gain at high signal-to-noise ratio,and single carrier system with TDC-CD achieves 2d B BER gain at 10~(-4).

Garment exporters Fearing Price Drop and Order Diversion

China’s textile exports achieved a positive growth of 25.2 percent in December last year,but apparel exports indicated a reduction of 4.

The Analysis of Secure HARQ with Chase Combining over Block Fading Channel

In this letter, the physical layer security of hybrid automatic repeat request with chase combining(HARQ-CC) scheme is investigated from the viewpoint of information theory. Different from the literature which used Wyner code, our analysis focuses on the general scenario without specific code. We firstly obtain the outage probability of both main channel and wiretap channel. Since retransmissions are completely determined by main channel, we then prove that its achievable diversity order equals to maximum transmission number() while this order of wiretap channel is only one. Furthermore, we evaluate the metric of secure gap which demonstrates the difference between main channel and wiretap channel with reliable and secure constraints. As increases, the secure gap decreases monotonously. When is large enough, the security can be guaranteed even if wiretap channel is better than main channel.

LLR-AWARE SMART LINK-ADAPTIVE STRATEGY FOR DECODE-AND-FORWARD COOPERATIVE COMMUNICATION

Error propagation seriously degenerate the diversity order of Decode-and-Forward (DF) cooperative communication. To address this problem, a novel Log Likelihood Ratio (LLR)-based Link Adaptive Relaying (LAR) is proposed to promote adaption accuracy at relay. The instantaneous Bit Error Probability (BEP) is calculated according to the LLR of the received signals firstly, then based on it, the equivalent Signal-to-Noise Ratio (SNR) is employed to operate dynamic power scaling by relay. It is theoretically proved that the full diversity order can be attained by the scheme. Besides, the power sensitivity is also analyzed. Simulation results show that the proposed scheme outperform the conventional LAR and can achieve full diversity order. Moreover, its strong adaptation to SNR fluctuation is validated.