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In a hybrid automatic repeat request with chase combining (HARQ-CC) system,we analyze physical layer secure performance and determine the secrecy redundancy rateby proposed quasi-concave optimization methods with effective secrecy throughput (EST) criteria.First, key performance metrics, including connection outage probability (COP),secrecy outage probability (SOP), EST, and delay, are discussed.Then, under the constraint of COP, we optimize the secrecy redundancy rate to maximize the EST,which is a quasi-concave function, by both the bisection and fixed-point methods.Furthermore, under the simultaneous constraints of COP and SOP,the bisection and Lagrangian multiplier methods are applied to optimize the secrecy redundancy rate.From the comparison of the numerical and simulated results,it is concluded that EST demonstrates practical secure performance of HARQ-CC,and the proposed optimization methods adjust the secrecy redundancy rate for improved security.

Recently, a segmented analog-to-information conversion (S-AIC) structure that can obtain more samples than the number of branches of mixers and integrators (BMIs) is proposed by Taheri and Vorobyov. To reduce the complexity of S-AIC, in this paper we propose a Toeplitz-like segmented AIC (TS-AIC) structure, where the sampling waveforms are multiplexed in different BMIs and local permutation is performed to subsamples collected in each BMI. We show that the equivalent measurement matrix consists of several Toeplitz block matrices, which is then proved to satisfy the restricted isometry property. Simulations show that TS-AIC performs similarly as S-AIC.

创新点 针对无线衰落信道中物理层传输的安全问题, 提出了一种基于随机线性码的解决方案。 所提方案中, 发送方 (A) 使用的编码生成多项式由接收方 (B) 产生并发送给A。 生成多项式的产生满足一定的规则, 使得窃听方 (E) 如果漏掉A、 B双方数据包中的任何一个, 则无法解出任意一个信源数据包, 从而可以显著降低窃听方截获信息的概率。

Low-density parity-check (LDPC)-coded modulation has attracted much attention for its outstanding performance in a bandwidth-limited channel. However, it involves relatively high decoding complexity. Owing to different convergence behaviors of variable nodes, the nodes detected early can be deleted from the Tanner graph, which reduces the size of the parity-check matrix iteration by iteration and thus the decoding complexity. In this paper, we propose a new decoding algorithm for LDPC-coded modulation with reduced complexity. In addition, by deleting the converged bits from the modulation constellation and updating the bit metrics of the demapper with the reduced constellation, more accurate estimation of the bits can be achieved. Simulation results show that, compared with conventional decoding schemes, the proposed method not only greatly reduces the overall decoding complexity for LDPC-coded modulation but also significantly improves decoding performance.

A technique for bandwidth extension and noise optimization of wideband low-noise amplifier with dual feedback loops is presented. A LC-ladder matching network has been added in front of conventional amplifier with dual feedback loops. Detailed circuit analysis and general design procedures for the modified amplifier have been provided. The technique is applied to an amplifier covering the frequency range from DC to 6 GHz in a 0.5 μm InGaAs E-mode pHEMT process. Post-layout simulation shows S 11 below ?10 dB, S 22 below ?10 dB, flat S 21 of 16 ± 0.2 dB, and flat NF of 1.85 ± 0.35 dB across the entire band, which confirms the improvement in bandwidth and noise performance.

Collaborative transmission among evolved Node-Bs (eNBs) is one of the promising techniques for LTE-Advanced to provide broader coverage and higher spectral efficiency. The interference among multi-cell transmission can be mitigated by joint precoding, such as multi-cell block diagonalization (BD) at cooperative eNBs. The major difference between multi-cell and single-cell transmission is that the power constraint has to be considered on a per-eNB basis. To satisfy per-eNB power constraint (PePC), a simplified power allocation algorithm for the multi-cell BD based collaborative transmission is proposed in this paper. The algorithm provides a power allocation coefficient matrix for BD to meet PePC. Simulation results demonstrate that the proposed algorithm has a near-optimal performance with simplicity.