Zhuoming Li

Downlink CoMP resource allocation based on limited backhaul capacity

Coordinated Multi-Point (CoMP) transmission is put forward in the Long Term Evolution-Advanced (LTE-A) system to improve both average and cell-edge throughput. In this paper, downlink CoMP (DL-CoMP) resource allocation scheme based on limited backhaul capacity is designed to take a tradeoff between system throughput and fairness. Resource allocation of proportional fairness based on querying table is proposed. It updates RB allocation matrix when center cell has completed resource allocation and delivers the matrix to adjacent cells for their own RB allocation. Furthermore, Water-Filling algorithm based on adaptive water level (AWF) is used for power allocation to boost system fairness. In this paper, performance of downlink CoMP based on limited backhaul capacity and single-point transmission is contrasted, and results indicate that CoMP dramatically enhances system throughput and spectral efficiency. Moreover, AWF power allocation scheme obtains higher system fairness than conventional Water-Filling (WF) algorithm, although it gets slightly lower system throughput. Finally, this paper discussed that the system performance is partially affected by the percentage of CoMP resource.

Power Allocation for CoMP in LTE-advanced system

CoMP is one of key technologies in LTE-Advanced system to eliminate inter-cell interference, enhance system throughput and cell-edge spectrum efficiency. CS/CB (Coordinated Scheduling/Coordinated Beamforming) and JT (Joint Transmission) are two main technologies of CoMP. In this paper, cell-edge users transmit data by JT scheme, and cell-center users adopt CB scheme to eliminate interference. Precoding algorithm based on SLNR (Signal to Leakage and Noise Ratio) is adopted to improve quality of desired signal and restrain interference from adjacent cells. The proposed CoMP system gets more than 80% gain on both throughput and spectrum efficiency than single-point transmission. Based on the proposed coordinated system above, CoPA (Convex Optimization Power Allocation) power allocation scheme is proposed to maximize cell total data rates, subjected to maximum transmit power of each eNodeB. The proposed power allocation scheme achieves 2.3% gain on both throughput and spectrum efficiency compared with EPA (Equal Power Allocation).

Multi-objective network optimization combining topology and routing algorithms in multi-layered satellite networks

Dear editor, In satellite communication studies, the multilayered satellite network (MLSN) can take advantage of both wide coverage and low time delay. Furthermore, the issue of stable networking and dynamic reconstructing methods is still worth exploring. However, current studies rarely involve the combination of the routing algorithm and the network topology. In [1, 2], two MLSN designs are introduced, but the design of the inter-satellite link is ignored. Most routing algorithms in satellite networks concentrate on improving network performance, such as quality of service (QoS) [3], computation complexity [4] and load balancing [5], but most are based on a given static topology without considering topology dynamics. This study focuses on optimizing and reconstructing the MLSN under multi-objective QoS constraints by combining topology and routing algorithms. The feasibility of combing topology and routing is analyzed. Besides, a network initialization is completed to offer an initial topology for optimization. A multiobjective optimization (MOP) model is proposed to optimize multiple QoS parameters in the routing algorithm, and a network optimization combing topology and routing algorithm is introduced. A heuristic networking scheme balances the network cost and the requirement. Satellite network architecture. This study uses a classic MLSN architecture [2]. Assuming the constellation has enough nodes and links, six low-Earth orbit (LEO) satellite nodes under one medium-Earth satellite’s coverage in the MLSN are selected to form a network architecture. Feasibility analysis. Most routing algorithms are based on a static topology [4,5], thus, the network topology unidirectionally affects the routing algorithm, but the effect produced by the distribution of different time delays and network bandwidths is ignored. Besides, although an optimum solution can be obtained using certain routing algorithms, resources can be wasted without reconstructing the topology. Therefore, it is necessary to combine the topology and the routing algorithm to optimize the network. In addition, the delay represents the routing characteristics, and the stability represents topological characteristics. As defined in [6], the average delay D is the ratio of the traffic transmitted on each path multiplied by the corresponding delay

A Multi-objective Network Optimization Algorithm Based on QoS in Distributed Constellation Networks

This paper proposes and analyzes a multi-objective optimization algorithm based on QoS in distributed constellation networks, combining the topology and routing algorithm to optimize and reconstruct the network, a new heuristic networking scheme is also proposed to balance the network cost and the requirement weight. The algorithm is capable of minimizing the total network delay, improving the link utilization and achieving optimization combined with multi-QoS. The simulation results show that our algorithm and scheme can meet the needs of different network designs, optimize the performance and solve the problem of dynamic networking and network reconstruction, providing a basis for the research in combination of topology and routing in satellite networks.

Research on the Resource Allocation Algorithm in the WFRFT-Based Hybrid-Carrier System

In high speed mobile communication environment, time dispersion caused by multipath interference and frequency dispersion caused by Doppler shift weaken the effect of traditional frequency domain resource allocation algorithms on WFRFT-based hybrid-carrier systems. In order to solve this problem, this paper proposes a fractional domain resource allocation algorithm which is able to take the channel conditions into consideration. By adjusting the fractional order, the proposed method can suit different transmitted signals, therefore has better performance in time-frequency doubly dispersive channels. Simulation results show that the proposed fractional domain resource allocation algorithm has better BER performance than traditional frequency domain one in the hybrid-carrier system.

Study of Feature Extraction Algorithms for Epileptic Seizure Prediction Based on SVM

Epilepsy is a common brain disease state, which threatens the safety of patients. So the effective prediction of epilepsy has great significance. To predict the epileptic seizure, energy feature of electroencephalogram (EEG) is extracted by wavelet transformation and power spectral. Then, support vector machine (SVM) is applied to separate the feature data. The research result shows that the energy of frequency band 0.5–8 Hz would rise 2000 s before seizure onset by analyzing inter-ictal and pre-ictal EEG’s wavelet energy. We used relative wavelet energy and SVM to analyze and test 8 patients’ EEG data, and it shows that the algorithm can predict some patients’ seizure onset except a few of patients’ bad behavior. We replace the wavelet with spectral power and use it to extract feature. The predict accuracy is improved by using spectral power and SVM. Comparing to the relative wavelet energy, the result of 6 patients’ test data improved by spectral power.

Research on coverage and link of multi-layer Satellite Network based on STK

This paper proposed a multi-layer satellite network to archive the global communication, facilitate the complexity of link handover and create the permanent link. The STK (Satellite Tools Kit) is used to design the satellite network according to the simulation objects including the scenario, satellite, facility and constellation, and further more the coverage analysis and link analysis capabilities are respectively designed to study the network performance. A satellite library is also constructed to allow users to call existing satellites and the data transmission capability is designed for client to receive simulation data from server during the simulation. As the simulation results shown in this paper, the design of HSBN (Hierarchical Space-Based Network) can satisfy requirements of global coverage and permanent link. The proposed satellite network can realize the global communication and reduce link handover complexity over the entire operating cycle.

Design of TOD self-synchronization method in frequency hopping system

One of the main questions of frequency hopping (FH) is Frequency-hopping synchronization. In this paper, a TOD (time of day) self-synchronization based method of frequency hopping synchronization is proposed to archive the rapid and reliable synchronization in a high speed hoping system. This method designed a new structure of the synchronization information, which used special rules sending the synchronization information at the transmitter side and applied the slow scanning combined with the maximum likelihood (ML) algorithm to track the FH sequence at the receiver side. We established a simulation platform of frequency-hopping system to simulate the principle and processes of proposed method. The simulation results represented the advantages we archived at the high acquisition probability, the low false alarm rate, and the long synchronization keeping time. And also we discussed the relationship between the transmission BER and the acquisition probability.

Hybrid coordinated strategy of downlink coordinated multi-point transmission

Coordinated multi-point (CoMP) transmission is put forward in the long term evolution-advanced (LTE-A) system to improve both average and cell-edge throughput. CoMP-joint processing (JP) scheme can get a larger cell-edge throughput and a lower bit error rate (BER) than the CoMP-coordinated beamforming (CB) scheme, but it also has higher complexity due to data sharing. A hybrid coordinated strategy with parameter α, which indicates the proportion of users employing the CoMP-JP scheme, is proposed to apply the CoMP-JP scheme to improve the poorer communication quality of cell edge and employ the CoMP-CB scheme for other users to enhance average throughput and spectral efficiency. This paradigm selects users defined by the certain threshold of signal to interference plus noise power ratio (SINR) corresponding to the parameter α to the CoMP-JP scheme. This paper compares the BER performance between the block diagonalization (BD) based precoding and the linear precoders by maximizing signal to leakage and noise ratio (SLNR), and also indicates that the SLNR based precoding algorithm gets lower BER than the BD based precoding algorithm with certain signal-to-noise ratios (SNRs). Finally, this paper discusses that the system performance is partially affected by the percentage of CoMP-JP users and concludes that 50% of users sorted to communicate under the CoMP-JP scheme will reach the best system performance.