Qiaoshou Liu

Bio: Qiaoshou Liu is an academic researcher from Chongqing University of Posts and Telecommunications. The author has contributed to research in topics: Computer science & Base station. The author has an hindex of 1, co-authored 1 publications receiving 6 citations. Previous affiliations of Qiaoshou Liu include University of Electronic Science and Technology of China.

Base Station Sleep and Spectrum Allocation in Heterogeneous Ultra-dense Networks

Abstract: To meet the exponential increasing high data rate demand of mobile users, heterogeneous ultra-dense networks (UDN) is widely seen as an essential technology to provide high-rate transmissions to nearby mobile users. However, the dense and random deployment of small base stations (SBSs) overlaid by macro base stations and their uncoordinated operation lead to important questions about the power consumption and aggressive frequency reuse of heterogeneous UDN. For the problem of huge power consumption and spectrum resource tension in heterogeneous UDN, a joint strategy of SBSs sleep and spectrum allocation is proposed. By using stochastic geometry, the coverage probabilities of base stations and the average ergodic rates of mobile users are derived in each tier and the whole network. In addition, we formulate the coverage probability maximization and power consumption minimization problems, and determine the optimal operating regimes for SBSs, and as well as spectrum allocation. The numerical results show that the SBSs sleep and spectrum allocation can reduce the power consumption and interference of the whole network.

Coverage and Meta Distribution Analysis in Ultra-Dense Cellular Networks with Directional Antennas

Abstract: This paper proposes a one-tier ultra-dense cellular network framework based on the characteristics of directional beamforming to explore the downlink signal-to-interference ratio (SIR) performance. The features of the proposed cellular network include: small base stations (SBSs) are equipped with directional antennas; the beam boresight directions of antennas are adaptively adjusted with the locations of users on the two-dimensional horizontal plane while the boresight directions are perfectly aligned with their associated users. In addition, an angle fading model, which follows from the exponential distribution, is developed to simulate the signals attenuation of interference links. The angle fading of the interference signals depends on the angle offset between the locations of users and the beam boresight directions of their interfering SBSs. With the assistance of stochastic geometry, the analytical expressions of coverage probability and average ergodic rate are derived by combining with the probability density function of angle offset variable. Then, the meta distribution of SIR is obtained to capture the performance changes of individual links for users. The numerical results indicate that the performance advantages of the proposed directional network obviously exceed that of the conventional isotropic antennas case. Monte-Carlo simulations validate the correctness of numerical results.

An Analysis of Distributed Joint Spectrum Resource Allocation With Power Control in Ultra-Dense Cellular Networks

Abstract: In the view of spatial statistical average, when users are associated with their nearest small base stations (SBSs), they are mainly interfered by their second closest SBSs, especially for edge users. To reduce inter-cell interference (ICI) caused by the second closest SBSs, a distributed joint spectrum resource allocation strategy with power control in the downlink of one-tier ultra-dense networks (UDNs) is proposed in this paper. According to the distance from users to their nearest SBSs, users are divided into inner users and edge users. We then try to make the subchannel randomly allocated so they be different from that of edge users of their second closest SBS. Meanwhile the transmission power of SBSs on different subchannels is adjusted. Using stochastic geometry we derive the analytical expressions of the meta distribution of signal-to-interference ratio (SIR) to obtain more fine-grained information such as the mean and variance of conditional success probability, the local delay. Furthermore, we revise and redefine the area spectrum efficiency (ASE) and energy efficiency (EE) to accurately evaluate the benefits. Compared with the traditional random resource allocation strategy, which does not exploit resource allocation and interference coordination scheme, the proposed strategy can balance the performance of users and improve the whole network EE. Our analytical results are validated through simulation.

Performance Analysis of Distance-Based D2D Matching Mechanism

Abstract: The traditional cellular architecture where devices connect to their service base station (BS) may cause poor performance especially for edge users. Device-to-device (D2D) communication enables nearby user as a relay to help BS forward information, thereby improving the network coverage and quality of service (QoS) of edge users. This paper proposes a distance-based D2D matching mechanism for general cellular networks, where a relay user who successfully connects to its targeted BS can transmit data to its closest user for D2D communication. A link of BS to D2D pair contains two sublinks, which occur at different time phases in each cell. Assuming a nonsynchronous system, we consider that there exists cross-layer interference for D2D links. Based on the techniques of stochastic geometry, we develop the performance of coverage probability and ergodic rate of the D2D network. A key intermediate step in this analysis is the derivation of the interference expressions for D2D links caused by BSs and cochannel D2D users. Then, we derive the meta distribution of the signal-to-interference ratio (SIR) to capture the performance changes of individual links. Simulation results demonstrate that our matching mechanism based on the appropriate time resource allocation favors the edge users with a higher probability of successful communication and transmission rate.

Research on End-to-End Wireless Communication System Based on Two Dimensional Convolution

Abstract: Aiming at the problem that the existing end-to-end automatic codec wireless communication systems do not perform well in multipath channel, this article proposed an improved auto-codec end-to-end wireless communication system. In this article, by changing the size of the convolution kernel, two dimensional(2-D) convolution is used to combat the frequency selective fading caused by the multipath effect, and the traditional OFDM module is combined with the auto-codec, so as to improve the ability of the system to cope with multipath. Simulation results show that the performance of the proposed 2-D convolution based self-codec end-to-end wireless communication system is improved by 17% and 60%, respectively, compared with the one dimensional(1-D) convolution self-codec wireless communication system and the traditional OFDM communication system in 5-path Rayleigh channel and 64QAM modulation.

5G-ZOOM-Game: small cell zooming using weighted majority cooperative game for energy efficient 5G mobile network

Abstract: The rapid escalation of user traffic and service innovation has made the deployment of small cell base stations essential for eventually decreasing energy consumption in future generation wireless network. An energy efficient small cell zooming strategy is proposed using weighted majority cooperative game for two-tier fifth generation (5G) mobile network. The proposed strategy is referred as ‘5G-ZOOM-Game’. Small cells ‘zoom in’ and ‘zoom out’ dynamically according to the proposed ‘5G-ZOOM-Game’ algorithm. Different frequency sets are assigned to small cells based on adjacency for reducing interference. In the proposed approach femtocells are used as small cells. The proposed algorithm is applied between two adjacent femtocells. Out of two adjacent femtocells, higher majority femtocell is selected based on weighted majority game; this femtocell zooms its coverage area. The utility function of the proposed approach is defined to connect maximum possible number of mobile devices by increasing the higher majority femtocell’s coverage area. Higher majority femtocell is chosen based on the load and minimum distance between mobile device and femtocell base station. Proposed 5G-ZOOM-Game network reduces ~ 35% of power consumption and increases signal-to-interference-plus-noise-ratio (SINR) and spectral efficiency by ~ 30% and ~ 60% respectively than the existing approaches.

User Association and Small-Cell Base Station On/Off Strategies for Energy Efficiency of Ultradense Networks

Abstract: The widespread application of wireless mobile services and requirements of ubiquitous access have resulted in drastic growth of the mobile traffic and huge energy consumption in ultradense networks (UDNs). Therefore, energy-efficient design is very important and is becoming an inevitable trend. To improve the energy efficiency (EE) of UDNs, we present a joint optimization method considering user association and small-cell base station (SBS) on/off strategies in UDNs. The problem is formulated as a nonconvex nonlinear programming problem and is then decomposed into two subproblems: user association and SBS on/off strategies. In the user association strategy, users associate with base stations (BSs) according to their movement speeds and utility function values, under the constraints of the signal-to-interference ratio (SINR) and load balancing. In particular, taking care of user mobility, users are associated if their speed exceeds a certain threshold. The macrocell base station (MBS) considers user mobility, which prevents frequent switching between users and SBSs. In the SBS on/off strategy, SBSs are turned off according to their loads and the amount of time required for mobile users to arrive at a given SBS to further improve network energy efficiency. By turning off SBSs, negative impacts on user associations can be reduced. The simulation results show that relative to conventional algorithms, the proposed scheme achieves energy efficiency performance enhancements.

Base Station Sleeping Strategy for On-Grid Energy Saving in Cellular Networks With Hybrid Energy Supplies in IoT Environment

Abstract: To efficiently reduce on-grid energy consumption, the base station (BS) sleeping strategy in the hybrid energy-powered cellular network (HybE-Net) in the Internet of Things environment is studied. In order to maximize on-grid energy saving, a BS sleeping algorithm, which adaptively and cooperatively adjusts the sleeping/non-sleeping state of BSs according to the actual traffic load and solar energy state, is proposed. Specifically, the solar energy state and dynamic characteristics of the BS in solar energy supply stage are analyzed by the approximation diffusion theory. Then, by comprehensively considering communication service quality and on-grid energy saving, BS sleeping constraints are derived mathematically. Subsequently, the BS sleeping problem in HybE-Net is formulated as the on-grid energy consumption maximization problem. To solve the optimization problem, a BS sleeping algorithm based on coalitional games is proposed. Finally, simulation results demonstrate that the proposed algorithm performs excellently in improving solar energy utilization and reducing on-grid energy consumption of the HybE-Net.

Energy-Efficient Ultra-Dense 5G Networks: Recent Advances, Taxonomy and Future Research Directions

Abstract: The global surge of connected devices and multimedia services necessitates increased capacity and coverage of communication networks. One approach to address the unprecedented rise in capacity and coverage requirement is deploying several small cells to create ultra-dense networks. This, however, exacerbates problems with energy consumption and network management due to the density and unplanned nature of the deployment. This review discusses various approaches to solving energy efficiency problems in ultra-dense networks, ranging from deployment to optimisation. Based on the review, we propose a taxonomy, summarise key findings, and discuss operational and implementation details of past research contributions. In particular, we focus on popular approaches such as machine learning, game theory, stochastic and heuristic techniques in the ultra-dense network from an energy perspective due to their promise in addressing the issue in future networks. Furthermore, we identify several challenges for improving energy efficiency in an ultra-dense network. Finally, future research directions are outlined for improving energy efficiency in ultra-dense networks in 5G and beyond 5G networks.

Adaptive energy-efficient small cell sleeping and zooming in heterogeneous cellular networks

Abstract: With the rapid growth of the number of cellular network users and their tendency to share various multimedia files, providing better coverage for users and guaranteeing the quality of service (QoS) to serve them by base stations (BSs) are essential. On the other side, with the increase in the number of users and BSs, the power consumption augments in the cellular network. Heterogeneous network (HetNet), which consists of a large number of small cells deployed in the coverage of macrocell, can increase the network capacity. To fulfill the users’ demands and meanwhile reduce the power consumption, we present three energy-efficient adaptive sleeping, zooming, and zooming + sleeping schemes for ultra-dense HetNets to increase the minimum energy efficiency (EE) of small cell BSs (SBSs). In the proposed sleeping technique, the SBS with the minimum EE switches to sleep mode until the minimum EE is improved. The proposed zooming technique performs the user association and power control to maximize the EE of each SBS as well as utilize the lowest possible number of SBSs. Finally, SBSs with the minimum EE switches to sleep mode after applying the zooming technique. The proposed joint zooming and sleeping method reduces the total power consumption and SBS utilization ratio about 100% and 25%, respectively, compared to the static user association scheme, in which the users connect to the nearest SBS. Also, it enhances the SE and EE of static user association about 1.5 and 1.4, respectively, which indicate its efficiency.