Lei Ning

Fuzzy clustering based Group Vertical Handover decision for heterogeneous wireless networks

In overlay heterogeneous wireless networks, many mobile terminals may operate vertical handover simultaneously which is defined as Group Vertical Handover (GVHO). Conventionally, handover decision schemes designed for a single user may cause network congestion and increasing handover blocking probability in GVHO scenario. To provide seamless handover with QoS guarantee, a fuzzy clustering method (FCM) is proposed by combining the concurrent traffic attributes of GVHO users and the status of available candidate networks. After the combination, users are able to select the proper network based on the dynamic diagram, which is generated by FCM. The collision probability can also be decreased through allocating handover request properly in a specific time window. Compared to the other two schemes, the simulation results show that the proposed scheme reduces the handover blocking probability about 17% and 25% (the maximum rate) respectively.

A Novel SLM Method for PAPR Reduction of OFDM System

Given that the conventional Selected Mapping (SLM) scheme needs to multiply pseudo-random phase sequences to the transmitted data meanwhile transmitting the whole side information, an exhaustive entropy and chaotic phase sequence based SLM method was proposed for reduction the peak-to-average power ratio (PAPR) of Orthogonal frequency division multiplexing (OFDM) in the paper. In the novel algorithm, exhaustive entropy was used to evaluate the randomness of phase sequence, chaotic sequences to reduce the large side information and improved Lorenz sequence digitalization method to enlarge sequence entropy, expanding the number of the candidate phase sequences vector space with the lower transmitted parameters of phase sequence. Simulation results show that different quantization methods of chaotic sequence have different exhaustive entropy and PAPR values. Furthermore, compared with the traditional SLM method, the new scheme proposed in the paper has better performance in reducing PAPR of OFDM system by about 0.1-0.5dB.

An exhaustive entropy based SLM method for PAPR reduction of OFDM systems

Orthogonal frequency division multiplexing (OFDM) is an attractive technology to provide immense improvements in wireless transmission capacity but high peak-to-average power ratio (PAPR) is a major drawback of OFDM system. Selected mapping (SLM) scheme has good performance for PAPR reduction. It requires the transmitting data to be multiplied by random phase sequences. However, the sequences are pseudo-random which will decrease the method effectiveness. Exhaustive entropy is introduced in this paper which can identify the strength of random phase sequences property. Then an exhaustive entropy based SLM method is proposed. The scheme improves the effectiveness of random phase sequences by selecting the larger exhaustive entropy of them. Simulation results show that the PAPR reduction performance is better than that of conventional SLM through this method.

Preferred Route Indoor Mobility Model for Heterogeneous Networks

A more realistic mobility model for indoor environments will greatly facilitate the development of optimal algorithms for small cells in Heterogeneous Networks (HetNets). However, models devised for macroscopic scene are no longer applicable in circumstances. In this letter, a algorithm called Preferred Route Indoor Mobility Model (PRIMM) is proposed. It utilizes Hidden Markov Model (HMM) and Shortest Path Algorithm (SPA) to perform mobility modelling, which focuses on residential homes and offices. Simulation results show that it can better model specific node motions with the physical constraints of the building layout, which are motivated by events sequences in various time states and routed by individual preference.

Tracking Areas Planning Based on Community Detection in Heterogeneous and Small Cell Networks

Increasing demands of data transmissions are promoting the acceleration of peaking rate per terminal especially in hot-spots. Numerous irregular deployments of small cells require efficient tracking area (TA) planning method in heterogeneous cellular networks. Macrocells preferred access is not a fundamental solution for TA planning, which results from reducing the offloading ability of small cells. In this paper, a novel TA planning algorithm based on cooperative games is proposed by detecting similar communities. Simulation results show that it can reduce the signalling overhead, improve the performance of calling successes and system utilizations while maintaining the offloading abilities of small cells.

Tracking Areas Planning with Cooperative Game in Heterogeneous and Small Cell Networks

Increasing demands of data transmissions are promoting the acceleration of peaking rate per terminal especially in hot-spots. Numerous irregular deployments of small cells require efficient TA planning method in heterogeneous cellular networks. Macrocells preferred access is not a fundamental solution for TA planning, result from reducing the offloading ability of small cells. In this paper, a novel TA planning algorithm based on cooperative games is proposed by detecting similar communities. Simulation results show that it can reduce the signalling overhead while maintaining the utilization proportion of femtocells.

Design of cooperation-based remote laboratory for distributed experimentation and simulation

With the increase of science project in size and complexity, it is necessary to integrate and share global research resources for distributed experimentation and simulation. This paper presents an architecture of Cooperative Remote Laboratories (CRLab) with scalability, flexibility and heterogeneity. It consists of a central Web server, simulation servers, instrument servers and experiment devices, which provide four logical functions including Parallel Computing, Virtual Instrument, Collaborative Simulation and Web 2.0. Based on these functions with interactive online features, the research can be more efficient and convenient just via a simple Web browser.

Equivalent cost ring model for CAC in heterogeneous wireless networks

Due to the respective developments of various radio access technologies, some geographical areas may be covered simultaneously by different wireless networks. The cooperation of these networks will not only meet the diverse quality of service requirements of mobile users but also efficiently utilize the resources of systems. As an important component of radio resource management, call admission control (CAC) is to decide whether a new call or a handover request can be accepted into a resource-constrained network. In such heterogeneous wireless environment, it needs more accurate metrics to measure the performances of mobility especially inside a cellular. In this paper, we propose a new equivalent cost ring based model to represent the complex heterogeneous wireless environment in a simplified and unified way. The coverage of base station is divided into regions based on the basic data rate. Using this model, we derive the mobility parameters such as new call blocking and handover failure probabilities. The system performances of heterogeneous networks are validated by simulations.