Yuanping Zhu

Cooperative distributed optimization for the hyper-dense small cell deployment

The fifth generation mobile networks will be developed to improve area spectral and energy efficiency, and provide uniform user experience. Hyper-dense small cell deployment can move devices closer to the wireless network and satisfy 5G system requirements. The main challenge of this network deployment results from the random deployment, dynamic on-off, flexible connection to cellular core networks, and flat system architecture of 5G systems. Therefore, conventional network planning and radio resource management, which depend on a central control node, cannot be applied to small cell networks. In this article some cooperative distributed radio resource management algorithms for time synchronization, carrier selection, and power control are discussed for hyper-dense small cell deployment.

Downlink Average Rate and SINR Distribution in Cellular Networks

The statistical characteristics of the signal-to-interference plus noise ratio (SINR) are closely related to many performance metrics of cellular networks. In this paper, the downlink average rate and SINR distribution are studied for orthogonal frequency division multiple access (OFDMA)-based cellular networks subject to the distance-dependent path loss and shadow fading (SF). With the analytical approximate mean and moment generating function (MGF) of the SINR in the logarithmic domain, the closed-form approximation for the lower and upper bounds of the average rate is obtained. Then the distribution of the SINR in the logarithmic domain is proposed to be approximated as the normal inverse Gaussian (NIG) distribution whose parameters are computed explicitly through moment matching. Also, the closed-form expression for the cumulative distribution function (CDF) of the SINR based on the NIG approximation is derived. Simulation results not only verify the tightness of the bounds, but also show that the NIG approximation is up to one order of magnitude more accurate than the Pearson type IV approximation and at least one order of magnitude more accurate than the lognormal approximation when the SF correlation coefficient is small or the standard deviations of the SF are large or different.

Distribution of uplink inter-cell interference in OFDMA networks with power control

In frequency reuse one networks, the inter-cell interference (ICI) is severe especially for cell edge user equipments (UEs). Statistical information of ICI is helpful to design interference mitigation schemes. This paper proposes a statistical model for the uplink ICI in orthogonal frequency division multiple access (OFDMA) networks with power control. The distance-dependent attenuation and correlated shadowing are included in the channel model. Through analyzing the random part related to distribution of users location and correlated shadowing, we derive the general parametric probability density function (PDF) of uplink ICI in logarithmic domain, and then use the derived model to investigate the distribution of ICI with typical power control schemes. Numerical results derived from theoretical calculations and Monte Carlo simulations verify the statistical model and the analysis.

Inter-cell interference statistics of uplink OFDM systems with Soft Frequency Reuse

Soft Frequency Reuse (SFR) has been widely used to deal with the severe ICI (Inter-Cell Interference) especially for cell edge users. This paper presents an analytical method to investigate the statistics of inter-cell interference in uplink when SFR scheme is adopted in OFDM (Orthogonal Frequency Division Multiplexing) systems. PDF (Probability Density Function) of ICI from one adjacent interfering cell is derived and then used to deduce the expectation and variance of ICI from multiple interfering cells. The derived results are validated through comparison with Monte Carlo simulations. In addition, the relationships between system parameters and statistics of ICI in different frequency bands are investigated. These contributions will give inspect into important guidelines to system optimization.

Statistical Analysis of Path Losses for Sectorized Wireless Networks

In modern mobile communication networks, such as 3G and 4G networks, sectorized antennas have been widely used to divide each cell into multiple sectors in order to improve coverage, spectrum efficiency, and quality of service. Large-scale path loss from a transmitting antenna to a receiving antenna should include: 1) propagation attenuation that depends on transmission distance; 2) shadowing that depends on surrounding environment; and 3) antenna loss that depends on a sectorized antenna pattern and transmission angle. An in-depth analysis of statistical characteristics of large-scale path losses involving with these three factors is crucial for the design, operation, evaluation, and optimization of modern sectorized wireless networks. In this paper, a sectorized antenna pattern is, for the first time, considered in the derivation of a closed-form expression of a probability density function (pdf) of large-scale path losses. Specifically, we first discover that the normalized pdf of propagation attenuation plus shadowing, which can be approximated by the Gaussian mixture model (GMM) with all system parameters, is fully determined by our newly defined metric

Inter-operator interference coordination for co-primary spectrum sharing in UDN

{10}/{\ln 10}{\beta }/{\sigma _{s}}

Statistical analysis of inter-cell interference in uplink OFDMA networks with soft frequency reuse

, namely, the attenuation exponent

Normal Inverse Gaussian Approximation to downlink inter-cell interference

\beta

Bregman-Based Inexact Excessive Gap Method for Multiservice Resource Allocation

to standard deviation of shadowing

METHOD FOR SHARING FREQUENCTY SPECTRUM BETWEEN NETWORKS

\sigma _{s}