Low-complexity optimal spatial channel pairing for AF-based multi-pair two-way relay networks

This paper considers a multi-pair two-way relay system with multi-antenna users and proposes a low-complexity optimal spatial channel pairing （SCP） strategy at the relay station （RS） for such a system. The proposed SCP scheme, following the BD-like beamformer at RS, pairs the uplink spatial subchannels of each user pair with the corresponding downlink spatial subchannels by maximizing sum-rate （Max-SR）. Furthermore, a new mathematical inequality （arrangement inequalities of a product） is developed and applied to obtain sufficient and necessary conditions for achieving Max-SR-SCP. This also yields a simple low-complexity implementation of the proposed SCP in contrast to the NP-hard complexity of the original Max-SR-SCP problem. Simulation results illustrate that the proposed Max-SR-SCP achieves substantial sum-rate gains over other pairing schemes.     

Research on user pairing algorithm for LTE femtocell uplink

In this article,a new simulated annealing based bit error rate pairing scheduling(SA-BPS)algorithm for LTE femtocell uplink virtual multiple input multiple output(V-MIMO)systems is proposed,which uses Round Robin(RR)criterion to decide the first user,and simulated annealing(SA)algorithm with objective function of bit error rate(BER)is suggested to decide the pairing users.The SA-BPS is considered not only to be used for inner layer user pairing within femtocell user equipments(HUEs)to increase spectrum efficiency,but also to be used for cross layer user pairing between HUEs and macrocell user equipments(MUEs)to cancel the cross layer interference from MUEs to HUEs.As a growth control coefficient is used in SA-BPS to control the growth of average BER of users in the pairing group,rapid user BER deterioration can be prevented by adopting a proper coefficient.Simulation results show that,the SA-BPS outperforms RPS,DPS,and the conventional SA algorithm in terms of BER performance,whether used for inner layer user pairing or cross layer user pairing.Also,the mode switching signal to interference ratio(SIR)threshold between inner and cross layer user pairing are obtained by simulation in three cross layer interference power distribution scenarios.     

A parallel ant colonies approach to de novo prediction of protein backbone in CASP8/9

Predicting the three-dimensional structure of proteins from amino acid sequences with only a few remote homologs,or de novo prediction,remains a major challenge in computational biology.The modeling of the protein backbone represents the initial phase of a protein structure prediction process.Using a parallel ant colony optimization based on sharing one pheromone matrix,this report proposes a parallel approach to predict the structure of a protein backbone.The parallel approach combines various sources of energy functions and generates protein backbones with the lowest energies jointly determined by the various energy functions.All free modeling targets in CASP8/9 are used to evaluate the performance of the method.For 13 targets in CASP8,two out of the predicted model1s selected by our approach are the best of the published CASP8 results,and seven out of the model1s are ranked in the top 10.For 29 targets in CASP9,20 out of the best models from our predictions are ranked in the top 10,and 11 out of the model1s are ranked in the top 10.     

基于能量特征和RBF神经网络的柱塞泵状态识别方法

柱塞泵状态发生改变时,其振动信号各频带的能量发生相应变化,利用各频带的能量特征可识别柱塞泵状态。基于此提出一种基于能量特征和径向基函数(radial basis function,RBF)神经网络的柱塞泵状态识别方法。首先利用改进阈值的小波包降噪方法对原信号进行降噪处理,然后对降噪后的信号进行经验模态分解(empirical modedecomposition,EMD),选取含主要状态信息的IMF(intrinsic mode functions)分量,提取能量特征作为神经网络的输入参数,识别柱塞泵的状态。同时利用小波包分析技术提取能量特征,并运用神经网络进行状态识别。应用实例表明,以EMD提取各频带能量作为特征参数的RBF神经网络状态识别方法比小波包分析提取各频带能量特征的方法具有更高的识别率,能有效地识别柱塞泵的状态。     

Lifetime maximization routing with network coding in wireless multihop networks

In this paper, we consider the lifetime maximization routing with network coding in wireless mul- tihop networks. We first show that lifetime maximization with network coding is different from pure routing, throughput maximization with network coding and energy minimization with network coding. Then we formulate lifetime maximization problems in three different cases of (i) no network coding, (ii) two-way network coding, and (iii) overhearing network coding. To solve these problems, we use flow augmenting routing (FA) for the first case, and then extend the FA with network coding (FANC) by using energy minimized one-hop network coding. After that, we investigate the influence of parameters of FANC, evaluate the performance of FANC with two-way and overhearing network coding schemes and compare it with that without network coding under two different power control models, namely, protocol and physical ones. The results show that the lifetime can be improved significantly by using network coding, and the performance gain of network coding decreases with the increase of flow asymmetry and the power control ability.     

A unified algorithm for mobility load balancing in 3GPP LTE multi-cell networks

3GPP long term evolution (LTE) is a promising candidate for the next-generation wireless network, which is expected to achieve high spectrum efficiency by using advanced physical layer techniques and flat network structures. However, the LTE network still faces the problem of load imbalance as in GSM/WCDMA networks, and this may cause significant deterioration of system performance. To deal with this problem, mobility load balancing (MLB) has been proposed as an important use case in 3GPP self-organizing network (SON), in which the serving cell of a user can be selected to achieve load balancing rather than act as the cell with the maximum received power. Furthermore, the LTE network aims to serve users with different quality-of-service (QoS) requirements, and the network-wide objective function for load balancing is distinct for different kinds of users. Thus, in this paper, a unified algorithm is proposed for MLB in the LTE network. The load balancing problem is first formulated as an optimization problem with the optimizing variables being cell-user connections. Then the complexity and overhead of the optimal solution is analyzed and a practical and distributed algorithm is given. After that, the proposed algorithm is evaluated for users with different kinds of QoS requirements, i.e., guaranteed bit rate (GBR) users with the objective function of load balance index and non-GBR (nGBR) users with the objective function of total utility, respectively. Simulation results show that the proposed algorithm leads to significantly balanced load distribution for GBR users to decrease the new call blocking rate, and for nGBR users to improve the cell-edge throughput at the cost of only slight deterioration of total throughput.     

Correction method for non-landing measuring of vehicle-mounted theodolite based on static datum conversion

During the non-landing measuring of vehicle mounted theodolite, especially under high-speed tracking measurement, the misalignment of theodolite’s center of mass and spindle etc. will cause high-frequency vibration of theodolite platform, increase the observation error of targets and even unbelievable results. In this paper, a correction method of non-landing measuring of theodolite based on static datum conversion is presented, which can effectively improve the observation accuracy of theodolite. The CCD camera is fixed to the theodolite platform to calculate the gesture shaking quantity of theodolite platform in geodetic coordinate system through the real time imaging of static datum. The observation results of theodolite are corrected by using such shaking quantity. The experiment shows that the correction accuracy exceeds 10 s of arc. The intrinsic parameter calibration technology of camera based on stellar angular distance and absolute conic put forward in this paper can prevent the estimated error of extrinsic parameters influencing the intrinsic parameter calibration and improve the intrinsic parameter calibration accuracy; the static datum conversion technology can reduce the influence of installation error of camera and theodolite platform on gesture measuring of the platform. The simulation experiment shows that when the shaking range of the platform is less than 30 min of arc, the influence of the three-axis installation error of camera within 3deg on the accuracy of correction results is less than 8 s of arc. The method in this paper can be extended to and used in the field of gesture shaking measuring and micro-structure deformation of various unstable platforms, therefore it is of important theoretical research significance and has wide engineering application prospect.