Xu Yubin

Hybrid FCM/ANN indoor location method in WLAN environment

WLAN hybrid indoor location method based on fuzzy c-mean clustering (FCM) and artificial neural network (ANN) is proposed in this paper. For any pattern matching based algorithm in WLAN environment, characteristics of received signal strength (RSS) or signal to noise ratio (SNR) to multiple access points (APs) are utilized to establish radio map in the off-line phase, and in the on-line phase, actual two or three dimensional coordinates of the mobile terminals (MTs) are estimated based on the comparison between the new recorded RSS or SNR and fingerprints stored in radio map. Although the feed-forward ANN with three layers is sufficient to approximate any continuous functions to a desired accuracy and optimize any mapping relationship between training inputs and targets, generalization ability is difficult to be guaranteed. So in order to bridge this gap, FCM method is proposed to select the reference points (RPs) affected by the multi-path effect. Based on this method, RSS or SNR recorded at these RPs is modified by the linear regression. Feasibility and effectiveness of this hybrid FCM and ANN method are verified according to the experimental comparison with ANN method without FCM modification.

Characteristics of Fingerprint Location Technology in WLAN Environment

In this paper, the factors which affect the positioning accuracy in WLAN environment have been discussed in off-line phase for fingerprint technology, including different time intervals, directions, temperature and dynamic environment. Firstly, some of the significant positioning technologies are introduced and also the basic design process of fingerprint method is proposed. Then, based on the experimental results, the influence on position accuracy under different environmental conditions is analyzed. Finally, the position accuracy can be significantly improved in the experimental platform based on WLAN technology introduced in this paper. The technical design method based on fingerprint and mathematical analysis for WLAN position technology can be used to satisfy the purpose of improving position accuracy effectively.

Accuracy Enhancement for Fingerprint-Based WLAN Indoor Probability Positioning Algorithm

This paper proposed an accuracy enhancement for fingerprint-based WLAN indoor probability positioning algorithm. Based on Bayes’ probability theory, the traditional probability positioning algorithm converts the new sample location coordinates corresponding to the posterior probability to a priori marginal probability, which leads to the reference point having the greatest product for the estimated location as the terminal coordinates. However, due to the limited quantity of recorded signal strength in the offline phase, new recorded signal strength, different from any signal strengths in the Radio map, will appear in the on-line phase, which means the reference point may not completely characterize the signal strength distribution of this point and result in a poorer poisoning accuracy Therefore, based on the accuracy of enhanced probabilistic location algorithm, this paper proposes to use Gaussian and polynomial continuous curve to realize the least square fitting for the original signal discrete intensity distribution, which achieves to improve the positioning accuracy. And also, this paper presents an experiment made in a WLAN indoor open environment with 8×9m2, and the results verify the feasibility and validity of the proposed algorithm.

A Novel JRRM Approach Working Together with DSA in the Heterogeneous Networks

Joint Radio Resource Management (JRRM) and Dynamic Spectrum Allocation (DSA) are both promising approaches in the heterogeneous networks to increase overall QoS and spectrum efficiency, which have already been taken into the framework of heterogeneous radio access networks of E2R. However, not much research has been done about how they could work together properly. In our opinion, JRRM should act according to the spectrum arrangement and planning of DSA among different RATs. This paper gives the load situation a new expression, through which JRRM would be informed of not only the load respected with the RAT considered but also the DSA’s planning about the spectrum and traffic distribution among RATs. JRRM could act in accordance with DSA. Simulative comparison demonstrates that the JRRM proposed in this paper performs better than the original JRRM when working together with DSA in heterogeneous scenarios.

ANN indoor position determination based on area correlation in WLAN environment

Indoor position determination based on artificial neural network (ANN) with area correlation is proposed in this paper. For any pattern matching based algorithm in WLAN environment, the characteristics of received signal strength (RSS) or signal to noise ratio (SNR) to multiple access points (APs) are utilized to establish radio map in the off-line phase, and in the online phase, the actual two or three dimensional coordinates of mobile terminals (MTs) are estimated based on the comparison between the new recorded RSS or SNR and fingerprints stored in radio map. Although the feed-forward ANN with three layers is sufficient to approximate any continuous function to a desired accuracy and describe any mapping relationship between input and output values, the optimal types of input vectors for different actual complex indoor environments is difficult to be determined. So in this paper, the correlation between SNR from different APs and physical area is analyzed for the purpose of establishing multiple ANN subsystems for separate sub areas. Feasibility and effectiveness of this method is verified according to the experimental comparison with K-nearest neighbor (KNN), probability and ANN methods without area division.

Joint power control and proportional fair scheduling for D2D communication underlaying cellular networks

Device-to-Device (D2D) communication appears to be a promising component in 5G networks because of its increased spectral efficiency and reduced communication delay. But it also causes the co-channel interference to cellular networks. In this paper, we propose a new power control and resource scheduling scheme by taking into account the fairness, quality-of-service (QoS) requirements to deal with the issue of co-channel interference. The objective of our work is to maximize the sum of all users logarithmic utility functions. This is a NP-hard problem. We decomposed the optimization problem into two main subproblems. The first one is the problem of power control for a single D2D pair and its possible reuse candidates to maximize the overall throughput while ensuring signal-to-noise-and-interference (SINR) requirements of both D2D pair and its reuse candidates. The second one is the problem of Proportional Fair Scheduling (PFS) of resource for multiple D2D pairs and cellular users with a view to improving the system Fairness. We propose to use the Hungarian algorithm to address this issue. Simulation results showed that the proposed algorithm could significantly improve the system performance in terms of the system fairness and the overall system throughput while satisfying the QoS requirements of both D2D and cellular links.

Survey of WLAN fingerprinting positioning system

The increasing demand for indoor location based services has motivated the development of various indoor positioning methods. Among them, fingerprinting based positioning system in wireless local area network (WLAN) has been paid more attentions due to its cost effectiveness and relatively high accuracy. This paper investigates various optimization techniques for WLAN fingerprinting positioning comprehensively. The fingerprinting positioning comprises five major steps: Radio Map construction, location clustering, feature extraction, location estimation and tracking. The optimization techniques in these five steps are discussed and finally the future trends are presented.

TOA Estimate Algorithm Based UWB Location

Combining with UWB location technology, TOA location algorithm is presented. The first step is statistically averaging the received signals to mitigate impact of AWGN as long as possible. Using incoherent power detection algorithm obtain rude TOA estimation which is made incoherent power detection once more in the second step so as to further optimize in time. The simulation results show that the algorithm under low computational complexity can effectively improve ranging performance and location precision.

Interference Mitigated Receiver Based on Base Station Cooperation

Base station cooperation can mitigate interference of other cell in the uplink, in this paper future base stations cooperation architecture and information exchange scheme are proposed, receiver based on base station cooperation is designed, each station detected the weak signal information of users, which are transmitted to cooperative base station to combine and send demodulated signal to local base station. Meanwhile, in receiver, cooperation priority is analyzed which can reduce delay and improve throughput. The proposed receiver can efficiently mitigate OCI to improve system performance, providing new ideas for base station cooperation applying to realistic network.

A novel spatial Dynamic Spectrum Allocation in the urban heterogeneous scenario

Based on the research of spatial traffic distribution model in urban areas, this paper presents a novel urban spatial Dynamic Spectrum Allocation (DSA) according to the characteristics of spatial spectrum demand distribution in urban areas. A dynamic DSA area division method is investigated, which sets up a new neighboring relationship among the DSA areas. So part of the available spectrum is released from the heterogeneous interference limit, and the spatial DSA is conducted in a more flexible way with better performance. Simulative comparison demonstrates that the proposed urban spatial DSA in this paper outperforms the conventional spatial DSA in terms of spectrum satisfaction.